Publications by authors named "Krikor Bijian"

38 Publications

Chitosan/PCL nanoparticles can improve anti-neoplastic activity of 5-fluorouracil in head and neck cancer through autophagy activation.

Int J Biochem Cell Biol 2021 05 2;134:105964. Epub 2021 Mar 2.

Department of Otolaryngology Head and Neck Surgery, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, QC, Canada; Segal Cancer Centre and Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Departments of Medicine, Oncology, and Pharmacology and Therapeutics, Faculty of Medicine, McGill University, Montreal, QC, Canada. Electronic address:

Head and neck squamous cell carcinoma (HNSCC), a prevalent cancer worldwide, has a high incidence of loco-regional dissemination, frequent recurrence, and lower 5-year survival rates. Current gold standard treatments for advanced HNSCC rely primarily on radiotherapy and chemotherapy but with limited efficacy and significant side effects. In this study, we characterized a novel 5-fluorouracil (5-FU) carrier composed of chitosan solution (CS) and polycaprolactone (PCL) microparticles (MPs) in HNSCC preclinical models. The designed MPs were evaluated for their size, morphology, drug entrapment efficiency (EE%) and in vitro drug release profile. The anti-cancer activity of 5-FU-loaded particles was assessed in HNSCC human cell lines (CAL27 and HSC3) and in a preclinical mouse model (AT84) utilizing cell proliferation and survival, cell motility, and autophagy endpoints. The results demonstrated a 38.57 % in 5-FU entrapment efficiency associated with reduced 5-FU in vitro release up to 96 h post-exposure. Furthermore, CS-decorated PCL MPs were able to promote a significant inhibition of cancer cell proliferation based on the metabolic and colony formation assays, in comparison to controls. In contrast, CS-decorated PCL MPs did not influence the pharmacological efficacy of 5-FU to inhibit in vitro cancer cell migration. Last, cell protein analysis revealed a significant increase of autophagy and cell death evaluated by LC3-II expression and PARP1 cleavage, respectively. In summary, these results support the potential utility of CS-decorated PCL MPs as an effective 5-FU-delivery carrier to improve HNSCC therapeutic management.
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http://dx.doi.org/10.1016/j.biocel.2021.105964DOI Listing
May 2021

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition).

Autophagy 2021 Jan 8;17(1):1-382. Epub 2021 Feb 8.

University of Crete, School of Medicine, Laboratory of Clinical Microbiology and Microbial Pathogenesis, Voutes, Heraklion, Crete, Greece; Foundation for Research and Technology, Institute of Molecular Biology and Biotechnology (IMBB), Heraklion, Crete, Greece.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
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http://dx.doi.org/10.1080/15548627.2020.1797280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996087PMC
January 2021

Co-Overexpression of TWIST1-CSF1 Is a Common Event in Metastatic Oral Cancer and Drives Biologically Aggressive Phenotype.

Cancers (Basel) 2021 Jan 5;13(1). Epub 2021 Jan 5.

Segal Cancer Centre and Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Departments of Medicine, Oncology, and Pharmacology and Therapeutics, Faculty of Medicine, McGill University, Montreal, QC H3T 1E2, Canada.

Invasive oral squamous cell carcinoma (OSCC) is often ulcerated and heavily infiltrated by pro-inflammatory cells. We conducted a genome-wide profiling of tissues from OSCC patients (early versus advanced stages) with 10 years follow-up. Co-amplification and co-overexpression of , a transcriptional activator of epithelial-mesenchymal-transition (EMT), and colony-stimulating factor-1 (), a major chemotactic agent for tumor-associated macrophages (TAMs), were observed in metastatic OSCC cases. The overexpression of these markers strongly predicted poor patient survival (log-rank test, = 0.0035 and = 0.0219). Protein analysis confirmed the enhanced expression of TWIST1 and CSF1 in metastatic tissues. In preclinical models using OSCC cell lines, macrophages, and an in vivo matrigel plug assay, we demonstrated that gene overexpression induces the activation of while gene silencing down-regulates preventing OSCC invasion. Furthermore, excessive macrophage activation and polarization was observed in co-culture system involving OSCC cells overexpressing . In summary, this study provides insight into the cooperation between transcription factor and to promote OSCC invasiveness and opens up the potential therapeutic utility of currently developed antibodies and small molecules targeting cancer-associated macrophages.
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http://dx.doi.org/10.3390/cancers13010153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7795342PMC
January 2021

A novel orally available seleno-purine molecule suppresses triple-negative breast cancer cell proliferation and progression to metastasis by inducing cytostatic autophagy.

Autophagy 2019 08 1;15(8):1376-1390. Epub 2019 Mar 1.

a Segal Cancer Centre and Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Departments of Medicine and Oncology , McGill University , Montreal , QC , Canada.

Patients with triple-negative breast cancer (TNBC) often have a poor prognosis largely due to lack of effective targeted therapy. Using a library of seleno-purines coupled to a high-throughput biochemical enzymatic assays we identified a potent pharmacological enhancer of autophagy (referred herein as SLLN-15) that selectively activated cytostatic macroautophagy/autophagy in TNBC preclinical models. SLLN-15 induced a dose-dependent anti-proliferative activity in the TNBC cell lines MDA-MB-231 and BT-20 via induction of autophagy and autophagic flux. This induction was associated with a selective inhibition of AKT-MTOR signaling. Conversely, rapamycin, a known autophagy inducer and MTOR inhibitor, was unable to duplicate SLLN-15's effect on TNBC cells. Inhibition of autophagy by siRNA-mediated targeting of the autophagy regulators, and or using 3-methyladenine (3-MA), significantly protected against SLLN-15-induced inhibition of cell viability, further supporting that SLLN-15-induced inhibition of cancer cell proliferation was autophagy-dependent. SLLN-15-induced autophagy in TNBC cells was also associated with decreased AURKA expression, decreased AKT phosphorylation and subsequent blockage of the AKT-MTOR pathway. In vivo, oral SLLN-15 revealed a potent anticancer and anti-metastatic activity in mice bearing TNBC. Altogether, this study describes a novel regulator of mammalian autophagy, with potential utility as an experimental therapeutic for TNBCs. 3-MA: 3-methyladenine; ATG5: autophagy related 5; ATG7: autophagy related 7; AURKA: aurora kinase A; AURKB: aurora kinase B; BECN1: beclin 1; CQ: chloroquine; DMSO: dimethyl sulfoxide; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; ERBB2: erb-b2 receptor tyrosine kinase 2; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; PARP1: poly(ADP-ribose) polymerase 1; PI: propidium iodide; SQSTM1/p62: sequestosome 1; TNBC: triple-negative breast cancer.
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http://dx.doi.org/10.1080/15548627.2019.1582951DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6613893PMC
August 2019

MNK1/NODAL Signaling Promotes Invasive Progression of Breast Ductal Carcinoma .

Cancer Res 2019 04 18;79(7):1646-1657. Epub 2019 Jan 18.

Division of Experimental Medicine, McGill University, Montréal, Québec, Canada.

The mechanisms by which breast cancers progress from relatively indolent ductal carcinoma (DCIS) to invasive ductal carcinoma (IDC) are not well understood. However, this process is critical to the acquisition of metastatic potential. MAPK-interacting serine/threonine-protein kinase 1 (MNK1) signaling can promote cell invasion. NODAL, a morphogen essential for embryogenic patterning, is often reexpressed in breast cancer. Here we describe a MNK1/NODAL signaling axis that promotes DCIS progression to IDC. We generated MNK1 knockout (KO) or constitutively active MNK1 (caMNK1)-expressing human MCF-10A-derived DCIS cell lines, which were orthotopically injected into the mammary glands of mice. Loss of MNK1 repressed NODAL expression, inhibited DCIS to IDC conversion, and decreased tumor relapse and metastasis. Conversely, caMNK1 induced NODAL expression and promoted IDC. The MNK1/NODAL axis promoted cancer stem cell properties and invasion . The MNK1/2 inhibitor SEL201 blocked DCIS progression to invasive disease . In clinical samples, IDC and DCIS with microinvasion expressed higher levels of phospho-MNK1 and NODAL versus low-grade (invasion-free) DCIS. Cumulatively, our data support further development of MNK1 inhibitors as therapeutics for preventing invasive disease. SIGNIFICANCE: These findings provide new mechanistic insight into progression of ductal carcinoma and support clinical application of MNK1 inhibitors to delay progression of indolent ductal carcinoma to invasive ductal carcinoma.
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http://dx.doi.org/10.1158/0008-5472.CAN-18-1602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6513674PMC
April 2019

TRAF2 Cooperates with Focal Adhesion Signaling to Regulate Cancer Cell Susceptibility to Anoikis.

Mol Cancer Ther 2019 01 29;18(1):139-146. Epub 2018 Oct 29.

Segal Cancer Centre and Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Departments of Medicine, Oncology, and Pharmacology and Therapeutics, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.

TRAF2, a RING finger adaptor protein, plays an important function in tumor necrosis factor (TNF)- and TNF-like weak inducer of apoptosis (TWEAK)-dependent signaling, in particular during inflammatory and immune responses. We identified a functional interaction of TRAF2 with focal adhesion (FA) signaling involving the focal adhesion kinase (FAK) in the regulation of cell susceptibility to anoikis. Comparison of TRAF2-proficient (TRAF2) versus TRAF2-deficient (TRAF2), and FAK-proficient (FAK) versus FAK-deficient (FAK) mouse embryonic fibroblasts and their matched reconstituted cells demonstrated that TRAF2 interacts physically with the N-terminal portion of FAK and colocalizes to cell membrane protrusions. This interaction was found to be critical for promoting resistance to cell anoikis. Similar results were confirmed in the human breast cancer cell line MDA-MB-231, where TRAF2 and FAK downregulation promoted cell susceptibility to anoikis. In human breast cancer tissues, genomic analysis of The Cancer Genome Atlas database revealed coamplification of TRAF2 and FAK in breast cancer tissues with a predictive value for shorter survival, further supporting a potential role of TRAF2-FAK cooperative signaling in cancer progression.
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http://dx.doi.org/10.1158/1535-7163.MCT-17-1261DOI Listing
January 2019

MNK1/2 inhibition limits oncogenicity and metastasis of KIT-mutant melanoma.

J Clin Invest 2017 Nov 16;127(11):4179-4192. Epub 2017 Oct 16.

Segal Cancer Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montréal, Quebec, Canada.

Melanoma can be stratified into unique subtypes based on distinct pathologies. The acral/mucosal melanoma subtype is characterized by aberrant and constitutive activation of the proto-oncogene receptor tyrosine kinase C-KIT, which drives tumorigenesis. Treatment of these melanoma patients with C-KIT inhibitors has proven challenging, prompting us to investigate the downstream effectors of the C-KIT receptor. We determined that C-KIT stimulates MAP kinase-interacting serine/threonine kinases 1 and 2 (MNK1/2), which phosphorylate eukaryotic translation initiation factor 4E (eIF4E) and render it oncogenic. Depletion of MNK1/2 in melanoma cells with oncogenic C-KIT inhibited cell migration and mRNA translation of the transcriptional repressor SNAI1 and the cell cycle gene CCNE1. This suggested that blocking MNK1/2 activity may inhibit tumor progression, at least in part, by blocking translation initiation of mRNAs encoding cell migration proteins. Moreover, we developed an MNK1/2 inhibitor (SEL201), and found that SEL201-treated KIT-mutant melanoma cells had lower oncogenicity and reduced metastatic ability. Clinically, tumors from melanoma patients harboring KIT mutations displayed a marked increase in MNK1 and phospho-eIF4E. Thus, our studies indicate that blocking MNK1/2 exerts potent antimelanoma effects and support blocking MNK1/2 as a potential strategy to treat patients positive for KIT mutations.
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http://dx.doi.org/10.1172/JCI91258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663367PMC
November 2017

Efficacy of hybrid vitamin D receptor agonist/histone deacetylase inhibitors in vitamin D-resistant triple-negative 4T1 breast cancer.

J Steroid Biochem Mol Biol 2018 03 25;177:135-139. Epub 2017 Aug 25.

Department of Chemistry, McGill University, 801 Sherbrooke W., Montreal, QC, H3A 0B8, Canada. Electronic address:

Hormonal 1,25-dihydroxyvitamin D (1,25D) and its analogues have shown efficacy in some preclinical models of cancer. However, many models are resistant to the antiproliferative effects of 1,25D or its analogues in vitro or in vivo, and such compounds have failed in the clinic as monotherapies because of tumor resistance. Given the observed synergism between 1,25D analogues and histone deacetylase inhibitors (HDACi) in 1,25D-resistant cells, we previously developed a series of hybrid secosteroidal and easily assembled non-secosteroidal analogues that combined agonism for the vitamin D receptor and HDACi in a single backbone. These compounds displayed enhanced efficacy against 1,25D-resistant malignant cells in vitro. Structure/function studies led to synthesis of several non-secosteroidal variants in which HDACi potency was optimized without substantially sacrificing VDR agonism. Here, we present the first studies of efficacy in vivo of two of these compounds, DK-366 and DK-406, in the aggressive mouse 4T1 model of triple-negative breast cancer, a form of the disease for which treatment options are limited. 4T1 cells are resistant in vitro to the cytostatic and cytotoxic effects of 1,25D and the potent HDACi SAHA individually up to concentrations of 1μM and 50μM, respectively, whereas combinations of the two are efficacious. In vitro, DK-366 or -406 induced dose-dependent arrest of cell proliferation and cytotoxicity at 10-20μM. In vivo, the maximum tolerated dose (MTD) of DK-366 and DK-406 were 2.5 and 5.0mg/kg, respectively. Although the compounds induced hypercalcemia at elevated doses, consistent with VDR agonism in vivo, they both reduced tumor burden at doses below their MTD's. Moreover, in a separate experiment, DK-406 at 5mg/kg reduced 4T1 lung metastases by at least 50%. Under the same conditions, 1,25D (0.25μg/kg) and SAHA (25mg/kg) combined had no effect on tumor burden or on lung metastases. These experiments show that hybrid compounds are bioavailable and efficacious against a particularly aggressive model of metastatic breast cancer, providing strong support for the therapeutic potential of the hybrid concept.
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http://dx.doi.org/10.1016/j.jsbmb.2017.08.010DOI Listing
March 2018

Endosomal sorting and c-Cbl targeting of paxillin to autophagosomes regulate cell-matrix adhesion turnover in human breast cancer cells.

Oncotarget 2017 May;8(19):31199-31214

Lady Davis Institute for Medical Research and Segal Cancer Center, SMBD Jewish General Hospital, Departments of Medicine and Oncology, Faculty of Medicine, McGill University, Montreal, Canada.

Post-translational mechanisms regulating cell-matrix adhesion turnover during cell locomotion are not fully elucidated. In this study, we uncovered an essential role of Y118 site-specific tyrosine phosphorylation of paxillin, an adapter protein of focal adhesion complexes, in paxillin recruitment to autophagosomes to trigger turnover of peripheral focal adhesions in human breast cancer cells. We demonstrate that the Rab-7 GTPase is a key upstream regulator of late endosomal sorting of tyrosine118-phosphorylated paxillin, which is subsequently recruited to autophagosomes via the cargo receptor c-Cbl. Essentially, this recruitment involves a direct and selective interaction between Y118-phospho-paxillin, c-Cbl, and LC3 and is independent from c-Cbl E3 ubiquitin ligase activity. Interference with the Rab7-paxillin-autophagy regulatory network using genetic and pharmacological approaches greatly impacted focal adhesion stability, cell locomotion and progression to metastasis using a panel of human breast cancer cells. Together, these results provide novel insights into the requirement of phospho-site specific post-translational mechanism of paxillin for autophagy targeting to regulate cell-matrix adhesion turnover and cell locomotion in breast cancer cells.
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http://dx.doi.org/10.18632/oncotarget.16105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5458201PMC
May 2017

Insights into a novel nuclear function for Fascin in the regulation of the amino-acid transporter SLC3A2.

Sci Rep 2016 11 7;6:36699. Epub 2016 Nov 7.

Departments of Medicine, Oncology, Pharmacology and Therapeutics , Segal Cancer Centre and Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, 3755 Cote-Ste Catherine, Montreal, Quebec, H3T 1E2, Canada.

Fascin 1 (FSCN1) is a cytoskeleton-associated protein recognized to function primarily in the regulation of cytoskeleton structure and formation of plasma membrane protrusions. Here we report a novel nuclear function for Fascin 1. Biochemical studies and genome wide localization using ChIP-seq identified phosphorylated Fascin 1 (pFascin) in complexes associated with transcription and that it co-localizes with histone H3 Lys4 trimethylation (H3K4me3) on chromatin. Gene expression profiling identified genes affected by Fascin 1 including SLC3A2, a gene encoding for a plasma membrane transporter that regulates intracellular amino acid levels. RbBP5, a subunit of the H3K4 histone methyltransferase (HMT) complex was found to interact with Fascin 1 supporting its role in H3K4me3 establishment at target genes. Moreover, we show that changes to SLC3A2 levels affect amino acid-mediated mTORC1 activation. These results reveal that Fascin 1 has a yet undiscovered nuclear function as an epigenetic modulator of genes essential for amino acid metabolism.
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http://dx.doi.org/10.1038/srep36699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5098188PMC
November 2016

microRNA 338-3p exhibits tumor suppressor role and its down-regulation is associated with adverse clinical outcome in prostate cancer patients.

Mol Biol Rep 2016 Apr 23;43(4):229-40. Epub 2016 Feb 23.

Departments of Oncology, Biochemistry and Molecular Biology, Calgary, AB, Canada.

MicroRNAs (miRNAs) are small non-coding RNAs that function in transcriptional and post-transcriptional regulation of gene expression. Several miRNAs have been implicated in regulating prostate cancer (PCa) progression. Deregulations of miRNA regulatory networks have been reported in ERG positive PCa, which accounts for ~50 % of PCa and have been suggested to affect tumor aggressiveness. The function of miR338-3p, its prognostic significance, and its association with ERG positive PCa has not been fully investigated. Using microarray expression profiling, we identified miRNA338-3p as among the top deregulated miRNAs associated with ERG status in PCa. We investigated miR338-3p function using in vitro and in vivo experimental models and its expression was assessed and validated in clinical samples and a public cohort of localized and metastatic prostate cancer. miR338-3p was significantly down-regulated with disease progression from benign prostate tissue to primary and metastatic lesions. In localized disease, patients with lower miR338-3p expression levels showed increased association to biochemical recurrence and several adverse pathological parameters compared to patients with higher miRNA338-3p tissue expression levels. Using in vitro PCa cell models, overexpression of miR338-3p resulted in a decrease in cell invasion and expression of chemokine signalling genes CXCL12, CXCR4, and CXCR7. In vivo, orthotropic implantation of PC3 cells stably expressing miR338-3p was associated with a significant decrease in tumor weights compared to control cells. miR338-3p has anti-proliferative and anti-invasive properties. It affects CXCR4 axis, and its down-regulation is associated with adverse clinical outcomes in PCa patients.
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http://dx.doi.org/10.1007/s11033-016-3948-4DOI Listing
April 2016

Predominant Rab-GTPase amplicons contributing to oral squamous cell carcinoma progression to metastasis.

Oncotarget 2015 Sep;6(26):21950-63

Segal Cancer Centre and Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Departments of Medicine, Oncology, and Pharmacology and Therapeutics, Faculty of Medicine, McGill University, Canada.

Metastatic oral squamous cell carcinoma (OSCC) is frequently associated with recurrent gene abnormalities at specific chromosomal loci. Here, we utilized array comparative genomic hybridization and genome-wide screening of metastatic and non-metastatic tongue tumors to investigate genes potentially contributing to OSCC progression to metastasis. We identified predominant amplifications of chromosomal regions that encompass the RAB5, RAB7 and RAB11 genes (3p24-p22, 3q21.3 and 8p11-12, respectively) in metastatic OSCC. The expression of these Rab GTPases was confirmed by immunohistochemistry in OSCC tissues from a cohort of patients with a follow-up of 10 years. A significant overexpression of Rab5, Rab7 and Rab11 was observed in advanced OSCC cases and co-overexpression of these Rabs was predictive of poor survival (log-rank test, P = 0.006). We generated a Rab interaction network and identified central Rab interactions of relevance to metastasis signaling, including focal adhesion proteins. In preclinical models, mRNA and protein expression levels of these Rab members were elevated in a panel of invasive OSCC cell lines, and their down-regulation prevented cell invasion at least in part via inhibition of focal adhesion disassembly. In summary, our results provide insights into the cooperative role of Rab gene amplifications in OSCC progression and support their potential utility as prognostic markers and therapeutic approach for advanced OSCC.
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http://dx.doi.org/10.18632/oncotarget.4277DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4673138PMC
September 2015

Dynamin 2 interacts with connexin 26 to regulate its degradation and function in gap junction formation.

Int J Biochem Cell Biol 2014 Oct 28;55:288-97. Epub 2014 Sep 28.

Lady Davis Institute and Segal Cancer Center of the Sir Mortimer B. Davis Jewish General Hospital, Department of Medicine and Oncology, McGill University, Montreal, QC, Canada H3T 1E2. Electronic address:

Connexin 26 (Cx26), a protein involved in gap junctional intercellular communication, has an essential function during organ and tissue development. Its deregulation, in part due to inherent mutations, is associated with pathological conditions including congenital deafness. Regulation of Cx26 protein level is critical for its function but the molecular mechanisms involved are partially understood. This study identifies dynamin 2 (Dyn2) as a Cx26 interactor in yeast and mammalian cells. Deletion studies revealed that Cx26-Dyn2 interaction involves the C-terminus of Cx26 and the GTPase effector domain of Dyn2, which is of particular importance for the regulation of the endocytic pathway. Dyn2 inhibition using siRNA or dynasore resulted in reduced Cx26 degradation at the plasma membrane and this was associated with change in gap junctional intercellular communication (GJIC). Furthermore, we demonstrate that Dyn2 regulates Cx26 endocytosis and ubiquitination. These results establish Dyn2 as a Cx26 partner in the regulation of GJIC.
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http://dx.doi.org/10.1016/j.biocel.2014.09.021DOI Listing
October 2014

The significance of dynamin 2 expression for prostate cancer progression, prognostication, and therapeutic targeting.

Cancer Med 2014 Feb 18;3(1):14-24. Epub 2013 Dec 18.

Segal Cancer Center and Lady Davis Institute for Medical Research, Department of Oncology and Medicine, McGill University, Montreal, Quebec, Canada.

Dynamin 2 (Dyn2) is essential for intracellular vesicle formation and trafficking, cytokinesis, and receptor endocytosis. In this study, we investigated the implication of Dyn2 as a prognostic marker and therapeutic target for progressive prostate cancer (PCA). We evaluated Dyn2 protein expression by immunohistochemistry in two cohorts: men with localized PCA treated by retropubic radical prostatectomy (n = 226), and men with advanced/castrate-resistant PCA (CRPC) treated by transurethral resection of prostate (TURP) (n = 253). The role of Dyn2 in cell invasiveness was assessed by in vitro and in vivo experiments using androgen-responsive and refractory PCA preclinical models. Dyn2 expression was significantly increased across advanced stages of PCA compared to benign prostate tissue (P < 0.0001). In the CRPC cohort, high Dyn2 was associated with higher Gleason score (P = 0.004) and marginally with cancer-specific mortality (P = 0.052). In preclinical models, Dyn2 gene silencing significantly reduced cell migration and invasion in vitro, as well as tumor size and lymph node metastases in vivo. In isolated PCA cells, Dyn2 was found to regulate focal adhesion turnover, which is critical for cell migration; this mechanism requires full Dyn2 compared to mutants deficient in GTPase activity. In conclusion, Dyn2 overexpression is associated with neoplastic prostate epithelium and is associated with poor prognosis. Inhibition of Dyn2 prevents cell invasiveness in androgen-responsive and -refractory PCA models, supporting the potential benefit of Dyn2 to serve as a therapeutic target for advanced PCA.
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http://dx.doi.org/10.1002/cam4.168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930386PMC
February 2014

Total synthesis and biological activity of marine alkaloid Eudistomins Y1-Y7 and their analogues.

Mar Drugs 2013 Apr 29;11(5):1427-39. Epub 2013 Apr 29.

Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China.

Eudistomin Y class compounds are a series of β-carbolines which was originally isolated from a marine turnicate or ascidian near the South Korea Sea. These compounds contain bromo-substituted groups, which is one of the typical characters of marine natural products. We report herein the chemical synthesis and biological evaluation of seven new β-carboline-based metabolites, Eudistomins Y1-Y7, and their hydroxyl-methylated phenyl derivatives. Using bromo-substituted tryptamines and bromo-substituted phenylglyoxals as the key intermediates, Eudistomins Y1-Y7 and their derivatives were synthesized via the acid-catalyzed Pictet-Spengler reaction and fully characterized by 1H- and 13C-NMR and mass spectroscopy. Biological studies revealed that all of the compounds showed moderate growth inhibitory activity against breast carcinoma cell line MDA-231 with IC50 of 15-63 μM and the inhibitory activities of hydroxyl-methylated phenyl products were higher than that of the corresponding natural products Eudistomins Y1-Y7.
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http://dx.doi.org/10.3390/md11051427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707152PMC
April 2013

Synthesis and biological activity of novel organoselenium derivatives targeting multiple kinases and capable of inhibiting cancer progression to metastases.

Eur J Med Chem 2012 Feb 9;48:143-52. Epub 2011 Dec 9.

The Segal Cancer Center and Lady Davis Institute of the Sir Mortimer Jewish General Hospital, Montreal, Quebec, Canada.

The present study reports synthesis and biological activity of novel benzoisoselenazolone compounds derived from ebselen and conjugated to a sugar molecule. Cell proliferation assay using cancer cells combined with in vitro biochemical assays revealed that benzoisoselenazolone 2d, 5a, and 6a exerted anti-proliferative activity, which correlated with selective in vitro inhibition of focal adhesion kinase, AKT-1, and protein kinase C-α. Active molecules were able to significantly inhibit cell migration and invasion in vitro compared to cells treated with the vehicle alone or ebselen. Moreover, in vivo anticancer activity focusing on lead compound 2d and using an invasive human breast cancer orthotopic mouse model revealed a potent anti-metastatic activity at well-tolerated doses. In summary, these novel benzoisoselenazolones we report herein target multiple kinases with established roles in cancer progression and possess anti-invasive and anti-metastatic activity in preclinical models supporting a potential for therapeutic application for human disease.
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http://dx.doi.org/10.1016/j.ejmech.2011.12.006DOI Listing
February 2012

Total synthesis and bioactivity of the marine alkaloid pityriacitrin and some of its derivatives.

Eur J Med Chem 2011 Dec 25;46(12):6089-97. Epub 2011 Oct 25.

School of Medicine and Pharmacy, Key Laboratory of Marine Drugs, Ministry of Education, Ocean University of China, Qingdao, China.

We report herein the chemical synthesis and biological evaluation of β-carboline alkaloid pityriacitrin and some of its new derivatives. Using tryptophan or 5-hydroxytryptophan and 5-substituted indole-3-glyoxals as the starting materials, pityriacitrin and some of its derivatives were synthesized via the acid-catalyzed Pictet-Spengler reaction and fully characterized by (1)H and (13)C NMR, mass spectroscopy and IR determinations. Biological studies revealed that pityriacitrin has a weak antiproliferative activity against a panel of breast and prostate cancer cell lines, whereas some of its derivatives exhibited stronger and potent activity, which was associated with induction of both cell apoptosis and necrosis.
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http://dx.doi.org/10.1016/j.ejmech.2011.10.036DOI Listing
December 2011

Emerging drug discovery approaches for selective targeting of "precursor" metastatic breast cancer cells: highlights and perspectives.

Am J Transl Res 2011 8;3(5):434-44. Epub 2011 Sep 8.

Lady Davis Institute for Medical Research and Segal Cancer Center, Jewish General Hospital, Departments of Medicine, Oncology, and Pharmacology and Therapeutics, McGill University Montreal, Qc H3T1E2, Canada.

Breast cancer is a prevalent disease and a major cause of morbidity and cancer-related deaths among women worldwide. A significant number of patients at the time of primary diagnosis present metastatic disease, at least to locoregional lymph nodes, which results in somewhat unpredictable prognosis that often prompts adjuvant systemic therapies of various kinds. The time course of distant recurrence is also unpredictable with some patients sustaining a recurrence within months after diagnosis, even during adjuvant treatments, while others can experience recurrence years or decades after initial diagnosis. To date, clinically approved therapeutics yielded marginal benefits for patients with systemic metastatic breast disease, since despite high clinical responses to various therapies, the patients virtually always become resistant and tumor relapses. Molecular profiling studies established that breast cancer is highly heterogeneous and encompasses diverse histological and molecular subtypes with distinct biological and clinical implications in particular in relation to the incidence of progression to metastasis. The latter has been recognized to result from late genetic events during the multistep progression proposed by the dominant theory of carcinogenesis. However, there is evidence that the dissemination of primary cancer can also be initiated at a very early stage of cancer development, originating from rare cell variants, possibly cancer stem-like cells (CSC), with invasive potential. These precursor metastatic cancer cells with stem-like properties are defined by their ability to self-renew and to regenerate cell variants, which have high plasticity and intrinsic invasive properties required for dissemination and tropism toward specific organs. Equally relevant to the CSC hypothesis for metastasis formation is the epithelial-mesenchymal transition (EMT) process, which is critical for the acquisition of cancer cell invasive behavior and for selection/gain of CSC properties. These exciting concepts have led to the formulation of various approaches for targeting precursor metastatic cells, and these have taken on greater priority in therapeutic drug discovery research by both academia and pharmaceuticals. In this review, we focus on current efforts in medicinal chemistry to develop small molecules able to target precursor metastatic cells via interference with the CSC/EMT differentiation program, self-renewal, and survival. It is not meant to be comprehensive and the reader is referred to selected reviews that provide coverage of related basic aspects. Rather, emphasis is given to promising molecules with CSC/EMT signaling at the preclinical stage and in clinical trials that are paving the way to new generations of anti-metastasis drugs.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204890PMC
November 2011

PTEN deletion and heme oxygenase-1 overexpression cooperate in prostate cancer progression and are associated with adverse clinical outcome.

J Pathol 2011 May 7;224(1):90-100. Epub 2011 Mar 7.

Department of Pathology and Laboratory Medicine, University of Calgary and Calgary Laboratory Services, Calgary, Alberta, Canada.

Overexpression of the pro-survival protein heme oxygenase-1 (HO-1) and loss of the pro-apoptotic tumour suppressor PTEN are common events in prostate cancer (PCA). We assessed the occurrence of both HO-1 expression and PTEN deletion in two cohorts of men with localized and castration-resistant prostate cancer (CRPC). The phenotypic cooperation of these markers was examined in preclinical and clinical models. Overall, there was a statistically significant difference in HO-1 epithelial expression between benign, high-grade prostatic intraepithelial neoplasia (HGPIN), localized PCA, and CRPC (p < 0.0001). The highest epithelial HO-1 expression was noted in CRPC (2.00 ± 0.89), followed by benign prostate tissue (1.49 ± 1.03) (p = 0.0003), localized PCA (1.20 ± 0.95), and HGPIN (1.07 ± 0.87) (p < 0.0001). However, the difference between HGPIN and PCA was not statistically significant (p = 0.21). PTEN deletions were observed in 35/55 (63.6%) versus 68/183 (37.1%) cases of CRPC and localized PCA, respectively. Although neither HO-1 overexpression nor PTEN deletions alone in localized PCA showed a statistically significant association with PSA relapse, the combined status of both markers correlated with disease progression (log-rank test, p = 0.01). In a preclinical model, inhibition of HO-1 by shRNA in PTEN-deficient PC3M cell line and their matched cells where PTEN is restored strongly reduced cell growth and invasion in vitro and inhibited tumour growth and lung metastasis formation in mice compared to cells where only HO-1 is inhibited or PTEN is restored. In summary, we provide clinical and experimental evidence for cooperation between epithelial HO-1 expression and PTEN deletions in relation to the PCA patient's outcome. These findings could potentially lead to the discovery of novel therapeutic modalities for advanced PCA.
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http://dx.doi.org/10.1002/path.2855DOI Listing
May 2011

Endoplasmic reticulum stress in glomerular epithelial cell injury.

Am J Physiol Renal Physiol 2011 Sep 15;301(3):F496-508. Epub 2010 Dec 15.

Department of Medicine, McGill University Health Centre, McGill University, Montreal, Quebec, Canada.

Focal segmental glomerulosclerosis (FSGS) may be associated with glomerular epithelial cell (GEC; podocyte) apoptosis due to acquired injury or mutations in specific podocyte proteins. This study addresses mediation of GEC injury, focusing on endoplasmic reticulum (ER) stress. We studied signaling in cultured GECs in the presence or absence of the extracellular matrix (ECM). Adhesion to collagen supports cell survival, but adhesion to plastic (loss of contact with ECM) leads to apoptosis. Compared with collagen-adherent cells, GECs on plastic showed increased protein misfolding in the ER, and an adaptive-protective ER stress response, including increased expression of ER chaperones, increased phosphorylation of eukaryotic translation initiation factor-2α (eIF2α), and a reduction in protein synthesis. Activation of these ER stress pathways counteracted apoptosis. However, tunicamycin (a potent stimulator of ER stress) changed the ER stress response from protective to cytotoxic, as tunicamycin induced the proapoptotic ER stress gene, C/EBP homologous protein-10, and exacerbated apoptosis in GECs adherent to plastic, but not collagen. In GECs adherent to plastic, adaptive ER stress was associated with an increase in polyubiquitinated proteins and "choking" of the proteasome. Furthermore, pharmacological inhibition of the proteasome induced ER stress in GECs. Finally, we show that ER stress (induction of ER chaperones and eIF2α phosphorylation) was evident in experimental FSGS in vivo. Thus interactions of GECs with ECM may regulate protein folding and induction of the ER stress response. FSGS is associated with induction of ER stress. Enhancing protective aspects of the ER stress response may reduce apoptosis and possibly glomerulosclerosis.
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http://dx.doi.org/10.1152/ajprenal.00728.2010DOI Listing
September 2011

Glomerular epithelial cell injury associated with mutant alpha-actinin-4.

Am J Physiol Renal Physiol 2009 Oct 29;297(4):F987-95. Epub 2009 Jul 29.

Div. of Nephrology, Royal Victoria Hospital, 687 Pine Ave. West, Montreal, Quebec, Canada H3A1A1.

Focal segmental glomerulosclerosis (FSGS) may be associated with glomerular epithelial cell (GEC; podocyte) apoptosis due to acquired injury or mutations in alpha-actinin-4. This study addresses how FSGS-associated mutant alpha-actinin-4 may induce GEC injury, focusing on endoplasmic reticulum (ER) stress and metabolism of mutant alpha-actinin-4 via the ubiquitin-proteasome system. In a model of experimental FSGS induced by expression of an alpha-actinin-4 K256E transgene in podocytes, we show induction of ER stress, including upregulation of ER chaperones (bip, grp94), phosphorylation of the eukaryotic translation initiation factor-2alpha subunit, and induction of the proapoptotic gene C/EBP homologous protein-10 (CHOP). To address mechanisms of ER stress, we studied signaling in cultured GEC and COS cells expressing alpha-actinin-4 K256E. Previously, we showed that expression of this alpha-actinin-4 mutant in GEC increased apoptosis. In the present study, we show that alpha-actinin-4 K256E upregulates grp94 and CHOP expression in COS cells and significantly exacerbates induction of bip and CHOP in GEC in the presence of tunicamycin. ER stress was associated with aggregation and ubiquitination of alpha-actinin-4 K256E and impairment of the ubiquitin-proteasome system. In addition, alpha-actinin-4 K256E exacerbated apoptosis in the context of mild proteasome inhibition. Thus alpha-actinin-4 K256E triggers several metabolic abnormalities, which may lead to GEC injury and glomerulosclerosis.
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http://dx.doi.org/10.1152/ajprenal.00055.2009DOI Listing
October 2009

CD45 recruits adapter protein DOK-1 and negatively regulates JAK-STAT signaling in hematopoietic cells.

Mol Immunol 2009 Jul 28;46(11-12):2167-77. Epub 2009 May 28.

Department of Medicine, McGill University, Montreal, Quebec, Canada.

It has been extensively documented that CD45 positively regulates T cell receptor-mediated signaling through the activation of Src-family kinases. The mechanism whereby CD45 negatively regulates the JAK/STAT pathway, however, has not been fully elucidated. Here we describe the mechanism by which CD45 negatively regulates the JAK/STAT pathway through the recruitment of the inhibitory molecule Downstream of Kinase 1 (DOK-1) in hematopoietic cells. We present evidences that CD45 recruits DOK-1 to associate with tyrosine-phosphorylated DOK-1, and that the DOK-1-Y296F mutant completely abrogates its interaction with CD45. Moreover, CD45 expression is required for DOK-1 targeting to the plasma membrane in response to anti-CD3 stimulation. Functional studies further showed that stable expression of DOK-1 in K562 cells markedly decreased both JAK-2 and STAT-3/5 phosphorylation following IL-3 and IFN-alpha stimulation. Likewise, stable expression of DOK-1 in Jurkat cells significantly decreased JAK-2 phosphorylation. Similarly, both IL-3 and IFN-alpha-induced JAK-2 phosphorylations were significantly increased in CD45 deficient Jurkat cells. Consistently, silencing of the DOK-1 gene resulted in rescue of MAP kinases and JAKs activities in CD45 positive Jurkat cells. Accordingly, CD45 recruits adaptor DOK-1 to the proximal plasma membrane to serve as a downstream effector, resulting in negative regulation of the JAK/STAT signaling pathway.
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http://dx.doi.org/10.1016/j.molimm.2009.04.032DOI Listing
July 2009

Serum proteomic approach for the identification of serum biomarkers contributed by oral squamous cell carcinoma and host tissue microenvironment.

J Proteome Res 2009 May;8(5):2173-85

Department of Oncology and Medicine, Otolaryngology-Head and Neck Surgery, Lady Davis Institute for Medical Research and Segal Comprehensive Cancer Center, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada.

The lack of serum biomarkers for head and neck carcinoma limits early diagnosis, monitoring of advanced disease, and prediction of relapses in patients. We conducted a comprehensive proteomics study on serum from mice bearing orthotopic human oral squamous cell carcinomas (OSCC) with distinct invasive phenotypes. Matched established cell lines were transplanted orthotopically into tongues of RAG-2/gamma(c) mice and mouse serum was analyzed by 2-dimensional-differential gel electrophoresis(2D-DIGE)/liquid chromatography (LC)-MS/MS and by online 2D-LC-MS/MS of iTRAQ labeled samples. We identified several serum proteins as being differentially expressed between control and cancer-bearing mice and between noninvasive and invasive cancer (p<0.05). Differentially expressed proteins of human origin included the epidermal growth factor receptor (EGFR), cytokeratins, G-protein coupled receptor 87, Rab11 GTPase, PDZ-domain containing proteins, and PEST-containing nuclear proteins. Identified proteins of mouse origin included clusterin, titin, vitronectin, vitamin D-binding protein, hemopexin, and kininogen I. The levels of serum and cell secreted EGFR were further validated to match proteomic data regarding the inverse correlation with the invasive phenotype. In summary, we report a comprehensive patient-based proteomics approach for the identification of potential serum biomarkers for OSCC using an orthotopic xenograft mouse model.
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http://dx.doi.org/10.1021/pr800979eDOI Listing
May 2009

Fascin regulates prostate cancer cell invasion and is associated with metastasis and biochemical failure in prostate cancer.

Clin Cancer Res 2009 Feb;15(4):1376-83

Lady Davis Institute for Medical Research, Jewish General Hospital, Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.

Purpose: Prostate cancer metastasis to secondary organs is considered an initial event in the development of hormone refractory disease and remains the major cause of death among prostate cancer patients. In this study, we investigated the role of fascin, a cytoskeleton actin-bundling protein involved in the formation of filopodia and cell migration, in prostate cancer progression.

Experimental Design: Fascin protein expression was examined by immunohistochemistry in a cohort of 196 patients with localized prostate cancer and across several stages of disease progression, including hormone refractory disease. Cellular changes were also assessed in vitro and in vivo in DU145 prostate cancer cell line using fascin gene silencing.

Results: Fascin epithelial expression was significantly up-regulated in localized and hormone refractory prostate cancer compared with benign prostate tissue (P<0.05). Furthermore, high fascin expression was associated with an increased rate of prostate-specific antigen recurrence following radical prostatectomy (P=0.075), signifying more aggressive clinical course, thus supporting a function for fascin in prostate cancer progression. In cellular models, fascin gene silencing using small interfering RNA in the androgen-independent prostate cancer cell line DU145 decreased cell motility and invasiveness while increasing cell adhesive properties. In addition, fascin small interfering RNA-expressing DU145 cells implanted orthotopically in mouse prostate showed significantly decreased growth (P<0.005) and drastically prevented the formation of lymph node metastases (P<0.001) compared with their matched controls.

Conclusions: Our data show a function of fascin in the regulation of prostate cancer progression and emphasize the importance of fascin as a prognostic marker for aggressive disease and as a potential therapeutic target for advanced androgen independent disease.
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http://dx.doi.org/10.1158/1078-0432.CCR-08-1789DOI Listing
February 2009

Discovery of indoline-based, natural-product-like compounds as probes of focal adhesion kinase signaling pathways.

J Comb Chem 2009 Mar;11(2):303-9

Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada.

With the goal of identifying small molecule modulators of protein-protein interactions, we developed a solid-phase synthesis method, which was then successfully utilized in a library generation of 164 aminoindoline-derived, natural-product-like compounds. This library and several other related intermediates synthesized during this project were then subjected to different biological assays in search of small molecule modulators of focal adhesion kinase (FAK)-mediated signaling pathways. This study included (i) an in vitro, full length FAK inhibition assay, (ii) a cell proliferation assay, and (iii) a wound healing assay. In FAK inhibition assay, eight library members (5-12) and three aminoindoline derivatives (13, 14, and 2) were identified as promising candidates. Compounds 13 and 2 inhibited the FAK activity by 25-45% at 10 microM. These two lead compounds also showed activity in a wound healing assay. To our knowledge, these aminoindoline-derived small molecules belong to a new family of FAK inhibitors.
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http://dx.doi.org/10.1021/cc8001525DOI Listing
March 2009

Building skeletally diverse architectures on the Indoline Scaffold: the discovery of a chemical probe of focal adhesion kinase signaling networks.

Bioorg Med Chem 2008 Nov 12;16(21):9596-602. Epub 2008 Sep 12.

Ontario Institute for Cancer Research, MaRS Centre, South Tower, 101 College Street, Toronto, Ont., Canada M5G0A3.

Inspired by bioactive indoline alkaloid natural products, here, we report a divergent synthesis approach that led to skeletally diverse indoline alkaloid-inspired compounds. The natural product-inspired compounds obtained were then subjected to a series of in vitro and cellular assays to examine their properties as modulators of focal adhesion kinase (FAK) activity. This study resulted in the identification of a promising lead inhibitor of FAK (42), which also showed activity in a wound healing and cell invasion assay. The in silico study of the lead compound (42) was also undertaken.
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http://dx.doi.org/10.1016/j.bmc.2008.09.025DOI Listing
November 2008

Focal adhesion kinase-related proline-rich tyrosine kinase 2 and focal adhesion kinase are co-overexpressed in early-stage and invasive ErbB-2-positive breast cancer and cooperate for breast cancer cell tumorigenesis and invasiveness.

Am J Pathol 2008 Nov 2;173(5):1540-50. Epub 2008 Oct 2.

Department of Pathology, Lady Davis Institute of the Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Quebec, Canada.

Early cancer cell migration and invasion of neighboring tissues are mediated by multiple events, including activation of focal adhesion signaling. Key regulators include the focal adhesion kinase (FAK) and FAK-related proline-rich tyrosine kinase 2 (Pyk2), whose distinct functions in cancer progression remain unclear. Here, we compared Pyk2 and FAK expression in breast cancer and their effects on ErbB-2-induced tumorigenesis and the potential therapeutic utility of targeting Pyk2 compared with FAK in preclinical models of breast cancer. Pyk2 is overexpressed in tissues from early and advanced breast cancers and overexpressed with both FAK and epidermal growth factor receptor-2 (ErbB-2) in a subset of breast cancer cases. Down-regulation of Pyk2 in ErbB-2-positive, FAK-proficient, and FAK-deficient cells reduced cell proliferation, which correlated with reduced mitogen-activated protein kinase (MAPK) activity. In contrast, Pyk2 silencing had little impact on cell migration and invasion. In vivo, Pyk2 down-regulation reduced primary tumor growth induced by a metastatic variant of ErbB-2-positive MDA 231 breast cancer cells but had little effect on lung metastases in contrast to FAK down-regulation. Dual reduction of Pyk2 and FAK expression resulted in strong inhibition of both primary tumor growth and lung metastases. Together, these data support the cooperative function of Pyk2 and FAK in breast cancer progression and suggest that dual inhibition of FAK and Pyk2 is an efficient therapeutic approach for targeting invasive breast cancer.
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http://dx.doi.org/10.2353/ajpath.2008.080292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2570143PMC
November 2008

Early stage cancer cell invasion: signaling, biomarkers and therapeutic targeting.

Front Biosci 2008 May 1;13:6314-25. Epub 2008 May 1.

Segal Comprehensive Cancer Center, Lady Davis Institute of the Sir Mortimer B. Davis Jewish General Hospital, Department of Medicine, Faculty of Medicine, McGill University, 3755 Cote Ste-Catherine, Montreal, Canada H3T 1E2.

The process of primary cancer invasion of distant organs is multifactorial and multistep. Successful therapeutic management of invasive cancers remains hampered by the multitude of overlapping signaling pathways that initiate and drive cancer cell migration. A crucial early event by which cancer cells switch from localized to invasive states is initiated by the acquisition of autonomous motile properties; a process driven by dynamic assemblies and disassemblies of multiple focal adhesion, cytoskeleton and motor proteins. Several of the protein complexes involved are tightly regulated through posttranslational modifications and intermolecular collisions with partners that occur in a time- and space-dependent manner. These concerted mechanisms are essential for the regulation of cell shape, cell polarity, and cell motility and migration in response to chemotactic signals. This review summarizes the current knowledge in the field and potential clinical implications for molecular pathology and cancer therapeutics. It is not meant to be comprehensive; aspects related to basic signaling are not dealt with extensively in this review. However, the reader is referred to excellent reviews that provide coverage of these topics.
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http://dx.doi.org/10.2741/3156DOI Listing
May 2008

Role of apoptosis signal-regulating kinase 1 in complement-mediated glomerular epithelial cell injury.

Mol Immunol 2008 Apr 21;45(8):2236-46. Epub 2008 Feb 21.

Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada.

In the rat passive Heymann nephritis (PHN) model of membranous nephropathy, complement C5b-9 activates protein kinases in glomerular epithelial cells (GEC), and induces sublethal GEC injury and proteinuria. Complement induces production of reactive oxygen species (ROS) via the NAPDH oxidase, and stimulates phosphorylation of c-Jun N-terminal kinase (JNK) and p38 kinase in a ROS-dependent manner. In the present study, we demonstrate that apoptosis signal-regulating kinase 1 (ASK1) was activated in glomeruli of rats with PHN, and that incubation of GEC in culture with antibody and sublytic C5b-9 stimulated ASK1 activity. The latter was, in part, mediated via the NADPH oxidase and ROS. Sublytic complement induced JNK and p38 phosphorylation, which was amplified in GEC that stably overexpress ASK1, as compared with Neo (control) GEC. Complement-induced lysis was enhanced in GEC that overexpress ASK1, as compared with Neo, and was attenuated in GEC that overexpress a dominant negative ASK1 mutant. Inhibition of p38, but not JNK, attenuated complement lysis in GEC that overexpress ASK1, but not in Neo GEC. In Neo GEC, generation of ROS restricted complement-mediated GEC injury but the protective effect of ROS was lost when ASK1 was overexpressed. We propose that the level of ASK1 expression determines the functional effect of p38 activation, i.e. when ASK1 is overexpressed, p38 activation is amplified, and C5b-9 assembly leads to GEC injury via ASK1 and p38. The present study thus defines a novel role for ASK1 as a mediator of C5b-9-dependent cell injury.
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http://dx.doi.org/10.1016/j.molimm.2007.11.013DOI Listing
April 2008

Collagen-mediated survival signaling is modulated by CD45 in Jurkat T cells.

Mol Immunol 2007 Jul 23;44(15):3682-90. Epub 2007 May 23.

Mammalian Cell Genetics Group, Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount av., Montreal, Quebec H4P 2R2, Canada.

T cell activation is a critical step in the development of a proper immune response to infection and inflammation. This dynamic process requires efficient T cell receptor signaling, which in turn is modulated by integrin receptor activation and the actin cytoskeleton. CD45 is a key player in T cell receptor mediated signal transduction. However, its exact role in integrin mediated signaling in T cells remains to be elucidated. The present study addresses the relationship between CD45 and beta1-integrin mediated survival signaling in the human T leukemic cell line Jurkat, in which collagen receptors alpha1 beta1 and alpha2 beta1 integrins are localized. Wild type (WT)-Jurkat T cells treated with collagen demonstrated increased cell proliferation and survival. Monitoring the intracellular signaling pathways activated by collagen in WT-Jurkat cells revealed increased focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK) activation. Moreover, examination of the actin cytoskeleton of WT-Jurkat T cells treated with collagen demonstrated the presence of an organized cortical actin structure, reminiscent of the survival phenotype. This is in contrast to CD45-deficient J45.01 T cells, where collagen treatment failed to enhance cell proliferation/survival and was unable to stimulate FAK and ERK activity. In addition, the actin cytoskeleton of collagen treated J45.01 T cells was disorganized with cortical actin aggregates present throughout. The importance of an organized actin cytoskeleton to proper cell signaling and survival was further demonstrated by the inability of collagen treated WT-Jurkat cells to activate the FAK and ERK survival pathway in the presence of cytochalasin D, a cytoskeleton-disrupting drug. Consistently, addition of the CD45 specific inhibitor abolished collagen-stimulated FAK and ERK activation in WT-Jurkat cells, further depicting CD45 as the key mediator. Furthermore, collagen-mediated T cell signaling alone was able to activate IL-2 gene transcription devoid of concomitant T cell receptor activation. Taken together, these results are the first to demonstrate that CD45 is important in promoting cell survival by modulating integrin-mediated FAK/ERK signaling in Jurkat T cells and is involved in a distinct signal transduction pathway, separate from T cell receptor signaling, influencing T cell immune responses. Hence, this study will help further our knowledge about beta1-integrin mediated signaling in T cells, which may prove to be essential for the regulation of various T cell mediated immune responses.
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http://dx.doi.org/10.1016/j.molimm.2007.04.005DOI Listing
July 2007
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