Publications by authors named "Richard Jove"

146 Publications

Differences and similarities between cancer and somatic stem cells: therapeutic implications.

Stem Cell Res Ther 2020 11 18;11(1):489. Epub 2020 Nov 18.

NSU Cell Therapy Institute, Nova Southeastern University, 3301 College Ave, 3200 South University Drive, Fort Lauderdale, FL, 33328, USA.

Over the last decades, the cancer survival rate has increased due to personalized therapies, the discovery of targeted therapeutics and novel biological agents, and the application of palliative treatments. Despite these advances, tumor resistance to chemotherapy and radiation and rapid progression to metastatic disease are still seen in many patients. Evidence has shown that cancer stem cells (CSCs), a sub-population of cells that share many common characteristics with somatic stem cells (SSCs), contribute to this therapeutic failure. The most critical properties of CSCs are their self-renewal ability and their capacity for differentiation into heterogeneous populations of cancer cells. Although CSCs only constitute a low percentage of the total tumor mass, these cells can regrow the tumor mass on their own. Initially identified in leukemia, CSCs have subsequently been found in cancers of the breast, the colon, the pancreas, and the brain. Common genetic and phenotypic features found in both SSCs and CSCs, including upregulated signaling pathways such as Notch, Wnt, Hedgehog, and TGF-β. These pathways play fundamental roles in the development as well as in the control of cell survival and cell fate and are relevant to therapeutic targeting of CSCs. The differences in the expression of membrane proteins and exosome-delivered microRNAs between SSCs and CSCs are also important to specifically target the stem cells of the cancer. Further research efforts should be directed toward elucidation of the fundamental differences between SSCs and CSCs to improve existing therapies and generate new clinically relevant cancer treatments.
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http://dx.doi.org/10.1186/s13287-020-02018-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7672862PMC
November 2020

Synergistic Anti-Tumor Activity by Targeting Multiple Signaling Pathways in Ovarian Cancer.

Cancers (Basel) 2020 Sep 10;12(9). Epub 2020 Sep 10.

Department of Surgery, City of Hope National Med Center, Duarte, CA 91010, USA.

More effective therapy is needed to improve the survival of patients with advanced and recurrent ovarian cancer. Preclinical and early clinical studies with single molecular targeted agents have shown limited antitumor activity in ovarian cancer, likely due to compensation by alternative growth/survival pathways. An emerging strategy in overcoming resistance is to combine inhibitors targeting multiple pathways. In this study, we used a novel strategy of combining several FDA-approved targeted drugs, including sunitinib, dasatinib, and everolimus, in human ovarian cancers. Combination of the tyrosine kinase inhibitor sunitinib with the SRC inhibitor dasatinib showed synergistic anti-tumor activity in human ovarian cancer cells. The increased activity was associated with inhibition of the STAT3, SRC, and MAPK signaling pathways, but not AKT signaling. To inhibit the PI3K/AKT/mTOR pathway, we added the mTOR inhibitor everolimus, which further increased anti-tumor activity in cells. Combined treatment with sunitinib, dasatinib, and everolimus also resulted in greater inhibition of human ovarian tumor growth in mice. Furthermore, the triple combination also synergistically increased the anti-tumor activity of paclitaxel, both in vitro and in vivo. Taken together, our results demonstrate that simultaneous inhibition of several signaling pathways results in better anti-tumor activity compared to inhibiting any of these signaling pathways alone.
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http://dx.doi.org/10.3390/cancers12092586DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564386PMC
September 2020

Increasing Antitumor Activity of JAK Inhibitor by Simultaneous Blocking Multiple Survival Signaling Pathways in Human Ovarian Cancer.

Transl Oncol 2019 Aug 26;12(8):1015-1025. Epub 2019 May 26.

Department of Surgery, Beckman Research Institute, City of Hope Comprehensive Cancer Center, 1500 East Duarte Rd., Duarte, CA 91010. Electronic address:

Many signaling pathways, including the JAK/STAT3 pathway, are aberrantly activated and associated with ovarian cancer growth and progression. However, inhibition of STAT3 pathway alone was not sufficient to effectively block human ovarian cancer cell survival in vitro, which could be due to the activation and compensation of multiple survival pathways. In this study, we investigated a strategy that can enhance antitumor activity of JAK/STAT3 inhibitor by combining with inhibitors targeting other growth and survival pathways. We found that the in vitro activity of JAKi was remarkably increased when additional survival pathway was blocked. Blocking SRC pathway with SRC inhibitor (SRCi) increased the efficacy of JAKi more effectively than blocking AKT or MAPK pathway. The increased activity of JAKi in combination with SRCi is synergistic and associated with attenuation of p-STAT3, p-SRC, p-AKT and p-MAPK and increased inhibition of p-AKT. Simultaneous blockade of multiple survival pathways by combining JAKi with both AKT inhibitor (AKTi) and MEK inhibitor (MEKi) also resulted in a synergistic inhibition of cell survival. Furthermore, the combined treatment of JAKi and SRCi led to an increased apoptosis and greater inhibition of tumor growth and ascites formation. Taken together, our results demonstrate that the antitumor efficacy of JAKi is improved most effectively when combined with SRCi, providing a potential combination strategy for the treatment of advanced ovarian cancer.
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http://dx.doi.org/10.1016/j.tranon.2019.05.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6542771PMC
August 2019

Preliminary pharmacokinetic study of the anticancer 6BIO in mice using an UHPLC-MS/MS approach.

J Pharm Biomed Anal 2019 Feb 25;164:317-325. Epub 2018 Oct 25.

Division of Pharmacognosy and Natural Products Chemistry, School of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupoli Zografou, 15771, Athens, Greece. Electronic address:

Indirubins represent a group of natural and synthetic products with bio-activities against numerous human cancer cell lines acting by inhibiting protein kinases. The natural sources of indirubins are plants of Isatis sp., Indigofera sp., and Polygonum sp., recombinant bacteria, mammalian urine and some marine mollusks. Specifically, the halogenated derivative 6-bromo indirubin-3'-oxime (6BIO) possesses increased selectivity against GSK-3. However, to our knowledge, no analytical method to determine 6BIO in biological fluids has been developed till now. Therefore, a rapid, sensitive and high throughput UHPLC-MS/MS methods were developed and validated to evaluate the concentrations of 6BIO in mice plasma. Plasma samples were pre-treated by protein precipation using cold mixture of methanol: acetonitrile (9:1, v/v) and separations were carried out on a Hypersil Gold C18 column (50 × 2.1 mm i.d.; 1.9 μm p.s.) using 0.1% acetic acid and methanol as mobile phase at a flow rate of 500 mL/min in a gradient mode. For quantitation, a hybrid LTQ-Orbitrap MS equipped with an electro-spray ionization source was used applying a selected reaction monitoring (SRM) option. The monitored transitions were m/z 354.0 → 324.0 for 6BIO and 297.1 → 282.1 for afromorsin (used as the internal standard) in the negative mode. Following the EMA, ICH and FDA guidelines for validation of analytical procedures, the assay method was fully validated in terms of selectivity, linearity, recovery, matrix effect, accuracy, precision, stability, and robustness. The validated methods were successfully applied to the pharmacokinetic studies of 6BIO following an oral administration to mice at the dose of 50 mg/kg. The results indicated that 6BIO possesses a T of 30 min, a half-life of 1 h, and low plasma bioavailability.
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http://dx.doi.org/10.1016/j.jpba.2018.10.039DOI Listing
February 2019

Ruxolitinib synergistically enhances the anti-tumor activity of paclitaxel in human ovarian cancer.

Oncotarget 2018 May 31;9(36):24304-24319. Epub 2018 Jan 31.

Department of Surgery, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA.

Treatment for ovarian cancer remains challenging despite a high initial response rate to first line platinum-taxane treatment. Most patients eventually experience recurrence and require further treatment. Persistent activation of STAT3 is associated with cancer growth and progression and is also involved in cell resistance to platinum and taxane treatment. Targeting JAK/STAT3, therefore, could be a potential novel therapeutic approach for treating advanced and chemoresistant ovarian cancer. We investigated the therapeutic potential of ruxolitinib, a JAK1/JAK2 inhibitor that has been FDA-approved for the treatment of myelofibrosis, to treat ovarian cancer either alone or in combination with conventional chemotherapy agents. We show that ruxolitinib inhibits STAT3 activation and ovarian tumor growth both in ovarian cancer cells and in an ovarian cancer mouse model. In addition, ruxolitinib significantly increases the anti-tumor activity of chemotherapy agents, including paclitaxel, cisplatin, carboplatin, doxorubicin and topotecan in ovarian cancer cells. Evaluation of the combination index (CI) shows that ruxolitinib synergistically interacts with paclitaxel in all three human ovarian cancer cells. Finally, our results demonstrate that combination of ruxolitinib and paclitaxel leads to a greater reduction of tumor growth compared to single treatment of either agent in a tumor mouse model that represents late stage ovarian cancer with peritoneal metastasis and ascites formation. Taken together, our findings provide a foundation for clinical trials with ruxolitinib, either as a single agent or in combination with paclitaxel, for the treatment of recurrent and advanced ovarian cancer.
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http://dx.doi.org/10.18632/oncotarget.24368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5966246PMC
May 2018

JAK/STAT3-Regulated Fatty Acid β-Oxidation Is Critical for Breast Cancer Stem Cell Self-Renewal and Chemoresistance.

Cell Metab 2018 01 14;27(1):136-150.e5. Epub 2017 Dec 14.

Department of Immuno-Oncology, Beckman Research Institute and City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA. Electronic address:

Cancer stem cells (CSCs) are critical for cancer progression and chemoresistance. How lipid metabolism regulates CSCs and chemoresistance remains elusive. Here, we demonstrate that JAK/STAT3 regulates lipid metabolism, which promotes breast CSCs (BCSCs) and cancer chemoresistance. Inhibiting JAK/STAT3 blocks BCSC self-renewal and expression of diverse lipid metabolic genes, including carnitine palmitoyltransferase 1B (CPT1B), which encodes the critical enzyme for fatty acid β-oxidation (FAO). Moreover, mammary-adipocyte-derived leptin upregulates STAT3-induced CPT1B expression and FAO activity in BCSCs. Human breast-cancer-derived data suggest that the STAT3-CPT1B-FAO pathway promotes cancer cell stemness and chemoresistance. Blocking FAO and/or leptin re-sensitizes them to chemotherapy and inhibits BCSCs in mouse breast tumors in vivo. We identify a critical pathway for BCSC maintenance and breast cancer chemoresistance.
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http://dx.doi.org/10.1016/j.cmet.2017.11.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5777338PMC
January 2018

Prognostic Significance of Neutrophilic Infiltration in Benign Lymph Nodes in Patients with Muscle-invasive Bladder Cancer.

Eur Urol Focus 2017 02 25;3(1):130-135. Epub 2016 Mar 25.

Department of Pathology, University of California San Diego, San Diego, CA, USA.

Background: Preclinical studies suggest that signal transducer and activator of transcription 3 (STAT3)-mediated recruitment of neutrophils to premetastatic tissue occurs prior to metastatic progression.

Objective: We sought to determine if neutrophilic infiltration in benign nodal tissue is associated with poor clinical outcome in patients with muscle-invasive bladder cancer.

Design, Setting, And Participants: Formalin-fixed, paraffin-embedded tissue was secured from 55 patients with muscle-invasive bladder cancer who had undergone cystectomy at our institution. Sections of benign lymph nodes were obtained and stained with primary antibodies against 3-fucosyl-N-acetyl-lactosamine, phosphorylated STAT3, and interleukin-17, the latter being a key mediator of neutrophil infiltration and STAT3 activation.

Outcome Measurements And Statistical Analysis: The Kaplan-Meier method was used to interrogate differences in overall survival (OS) in patients with high versus low biomarker expression. Cohorts stratified by receipt and nonreceipt of neoadjuvant chemotherapy were separately explored.

Results And Limitations: Of the 55 patients examined, 19 patients (35%) had no prior neoadjuvant chemotherapy. Amongst these patients, median OS was improved in patients with low 3-fucosyl-N-acetyl-lactosamine cell counts (196 mo vs 37 mo; p=0.0062) and low phosphorylated STAT3 cell counts (278 mo vs 106 mo; p=0.025). In the same cohort, a trend towards improved OS in patients with low interleukin-17 cell count was observed (not reached vs 117 mo; p=0.18). No differences in OS were noted in biomarker-based subgroups amongst patients that had received prior neoadjuvant chemotherapy.

Conclusions: The results herein support the hypothesis that bladder cancer metastasis may be driven by STAT3-mediated neutrophilic infiltration in premetastatic sites. Validation of these findings using tissues derived from a phase 3 surgical trial (Southwest Oncology Group 1011) is currently underway.

Patient Summary: Lymph node metastases occur in up to 25% of patients with muscle-invasive cancer and it represents one of the most frequent sites of bladder cancer metastasis. This report provides preliminary evidence that neutrophil levels in benign lymph nodes may predict clinical outcome.
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http://dx.doi.org/10.1016/j.euf.2016.03.003DOI Listing
February 2017

Synthesis and antiproliferative activity of new pyrazolo[3,4-c]pyridines.

Med Chem 2016 Dec 13. Epub 2016 Dec 13.

School of Health Sciences, Department of Pharmacy, Division of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, Athens 15771, Greece.

Background: Several pyrazolopyridines possess promising pharmacological activities, mainly attributed to their antagonistic nature towards the natural purines in many biological processes. Cytotoxicity and anticancer potential of this class of compounds is mainly related to induction of apoptotic cell death and inhibition of protein kinases.

Objectives: This prompted us to design, synthesize and study the antiproliferative activity of a number of new 3,7-disubstituted pyrazolo[3,4-c] pyridines.

Methods: 2-amino-3-nitro-4-picoline was suitably modified and ring closed to provide 7-chloropyrazolo[3,4-c]pyridine. Iodination of this derivative was followed by the insertion of 3-aryl substituents via Suzuki coupling and aromatic nucleophilic substitution of the 7-chloro group by the appropriate amines. The antiproliferative activity of the target compounds was evaluated against A2058 melanoma, DU145 and PC3 prostate cancer cell lines. Flow cytometric analysis of DNA content for selected compounds was performed, after incubation of exponentially growing PC-3 cells.

Results: Eighteen new pyrazolopyridines have been synthesized and fully characterized. Among them, the majority of the 3-(3-fluorophenyl) derivatives exhibit interesting antiproliferative activity, with IC50 values in the range of 3.0-16.0 μM and present reasonable SARs. Cell-cycle perturbations revealed that the most active derivative 12a blocks cells at the S phase.

Conclusion: 3-(3-Fluorophenyl)-7-(4-methylpiperazin-1-yl)-1H-pyrazolo[3,4-c]pyridine (12a) and the corresponding 1-(4-methoxybenzyl)- analogue (11a) possess interesting antiproliferative activity against all cell lines tested. Derivatives bearing this substitution pattern can be considered as useful leads for further biological evaluation.
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December 2016

Natural-Based Indirubins Display Potent Cytotoxicity toward Wild-Type and T315I-Resistant Leukemia Cell Lines.

J Nat Prod 2016 10 11;79(10):2464-2471. Epub 2016 Oct 11.

Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center , 1500 East Duarte Road, Duarte, California 91010, United States.

Drug resistance in chronic myelogenous leukemia (CML) requires the development of new CML chemotherapeutic drugs. Indirubin, a well-known mutikinase inhibitor, is the major active component of "Danggui Longhui Wan", a Chinese traditional medicine used for the treatment of CML symptoms. An in-house collection of indirubin derivatives was screened at 1 μM on wild-type and imatinib-resistant T315I mutant CML cells. Herein are reported that only 15 analogues of the natural 6-bromoindirubin displayed potent cytotoxicity in the submicromolar range. Kinase assays in vitro show that eight out of the 15 active molecules strongly inhibited both c-Src and Abl oncogenic kinases in the nanomolar range. Most importantly, these eight molecules blocked the activity of T315I mutant Abl kinase at the submicromolar level and with analogue 22 exhibiting inhibitory activity at the low nanomolar range. Docking calculations suggested that active indirubins might inhibit T315I Abl kinase through an unprecedented binding to both active and Src-like inactive conformations. Analogue 22 is the first derivative of a natural product identified as an inhibitor of wild-type and imatinib-resistant T315I mutant Abl kinases.
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http://dx.doi.org/10.1021/acs.jnatprod.6b00285DOI Listing
October 2016

The discovery of new cytotoxic pyrazolopyridine derivatives.

Bioorg Med Chem Lett 2016 11 24;26(21):5229-5233. Epub 2016 Sep 24.

Laboratory of Cell Proliferation and Ageing, Institute of Biosciences & Applications, NCSR ''Demokritos", 15310 Athens, Greece.

A number of new 3,7-disubstituted pyrazolo[3,4-c]pyridines have been designed and synthesized from suitable 2-aminopyridines. The antiproliferative activity of the derivatives was determined against the pancreatic MIA PaCa-2 and ovarian SCOV3 cancer cell-lines. IC values of the most promising analogue 46 lie in the submicromolar or low micromolar range. Furthermore, compound 46 shows similar inhibitory activities against DU145, A2058 and PC-3 cancer cells, blocks the cell cycle at the G/G phase and induce apoptosis, as determined by the appearance of apoptotic nuclei.
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http://dx.doi.org/10.1016/j.bmcl.2016.09.056DOI Listing
November 2016

CD5 Binds to Interleukin-6 and Induces a Feed-Forward Loop with the Transcription Factor STAT3 in B Cells to Promote Cancer.

Immunity 2016 Apr;44(4):913-923

Department of Cancer Immunotherapeutics and Tumor Immunology, Beckman Research Institute and City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA.

The participation of a specific subset of B cells and how they are regulated in cancer is unclear. Here, we demonstrate that the proportion of CD5(+) relative to interleukin-6 receptor α (IL-6Rα)-expressing B cells was greatly increased in tumors. CD5(+) B cells responded to IL-6 in the absence of IL-6Rα. IL-6 directly bound to CD5, leading to activation of the transcription factor STAT3 via gp130 and its downstream kinase JAK2. STAT3 upregulated CD5 expression, thereby forming a feed-forward loop in the B cells. In mouse tumor models, CD5(+) but not CD5(-) B cells promoted tumor growth. CD5(+) B cells also showed activation of STAT3 in multiple types of human tumor tissues. Thus, our findings demonstrate a critical role of CD5(+) B cells in promoting cancer.
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http://dx.doi.org/10.1016/j.immuni.2016.04.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4844010PMC
April 2016

Convection-enhanced delivery of sorafenib and suppression of tumor progression in a murine model of brain melanoma through the inhibition of signal transducer and activator of transcription 3.

J Neurosurg 2016 May 6;124(5):1310-8. Epub 2015 Nov 6.

Division of Neurosurgery, Department of Surgery, City of Hope National Medical Center, Duarte, California; and.

OBJECT Despite recent advances, metastatic melanoma remains a terminal disease, in which life-threatening brain metastasis occurs in approximately half of patients. Sorafenib is a multikinase inhibitor that induces apoptosis of melanoma cells in vitro. However, systemic administration has been ineffective because adequate tissue concentrations cannot be achieved. This study investigated if convection-enhanced delivery (CED) of sorafenib would enhance tumor control and survival via inhibition of the signal transducer and activator of transcription 3 (Stat3) pathway in a murine model of metastatic brain melanoma. METHODS Melanoma cells treated with sorafenib in vitro were examined for signaling and survival changes. The effect of sorafenib given by CED was assessed by bioluminescent imaging and animal survival. RESULTS The results showed that sorafenib induced cell death in the 4 established melanoma cell lines and in 1 primary cultured melanoma cell line. Sorafenib inhibited Stat3 phosphorylation in HTB65, WYC1, and B16 cells. Accordingly, sorafenib treatment also decreased expression of Mcl-1 mRNA in melanoma cell lines. Because sorafenib targets multiple pathways, the present study demonstrated the contribution of the Stat3 pathway by showing that mouse embryonic fibroblast (MEF) Stat3 +/+ cells were significantly more sensitive to sorafenib than MEF Stat3 -/- cells. In the murine model of melanoma brain metastasis used in this study, CED of sorafenib increased survival by 150% in the treatment group compared with animals receiving the vehicle control (p < 0.01). CED of sorafenib also significantly abrogated tumor growth. CONCLUSIONS The data from this study indicate that local delivery of sorafenib effectively controls brain melanoma. These findings validate further investigation of the use of CED to distribute molecularly targeted agents.
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http://dx.doi.org/10.3171/2015.3.JNS132040DOI Listing
May 2016

MicroRNA-26a regulates insulin sensitivity and metabolism of glucose and lipids.

J Clin Invest 2015 Jun 11;125(6):2497-509. Epub 2015 May 11.

Type 2 diabetes (T2D) is characterized by insulin resistance and increased hepatic glucose production, yet the molecular mechanisms underlying these abnormalities are poorly understood. MicroRNAs (miRs) are a class of small, noncoding RNAs that have been implicated in the regulation of human diseases, including T2D. miR-26a is known to play a critical role in tumorigenesis; however, its function in cellular metabolism remains unknown. Here, we determined that miR-26a regulates insulin signaling and metabolism of glucose and lipids. Compared with lean individuals, overweight humans had decreased expression of miR-26a in the liver. Moreover, miR-26 was downregulated in 2 obese mouse models compared with control animals. Global or liver-specific overexpression of miR-26a in mice fed a high-fat diet improved insulin sensitivity, decreased hepatic glucose production, and decreased fatty acid synthesis, thereby preventing obesity-induced metabolic complications. Conversely, silencing of endogenous miR-26a in conventional diet-fed mice impaired insulin sensitivity, enhanced glucose production, and increased fatty acid synthesis. miR-26a targeted several key regulators of hepatic metabolism and insulin signaling. These findings reveal miR-26a as a regulator of liver metabolism and suggest miR-26a should be further explored as a potential target for the treatment of T2D.
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http://dx.doi.org/10.1172/JCI75438DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4497741PMC
June 2015

Synergistic anti-tumor effect of combined inhibition of EGFR and JAK/STAT3 pathways in human ovarian cancer.

Mol Cancer 2015 May 1;14:100. Epub 2015 May 1.

Department of Surgery, Beckman Research Institute, City of Hope Comprehensive Cancer Center, 1500 East Duarte Rd., Duarte, CA, 91010, USA.

Background: The EGFR signaling pathway is frequently activated in human ovarian cancer and associated with poor prognosis. However, inhibition of EGFR signaling in patients with recurrent ovarian cancer has been disappointing. It remains to be addressed whether ovarian cancer patients could benefit from targeting EGFR signaling. Here we investigated the mechanisms underlying the resistance to EGFR inhibition in ovarian cancer and developed a strategy to overcome it.

Results: We found that treatment of human ovarian cancer cells with an EGFR inhibitor, gefitinib, resulted in increased STAT3 phosphorylation in a dose- and time-dependent manner. Inhibiting STAT3 activation with a small molecule inhibitor of JAK, an upstream kinase that phosphorylates and activates STAT3, synergistically increased the anti-tumor activity of gefitinib in vitro. Similar results were obtained when STAT3 or JAK1 expression was knocked down. In contrast, inhibiting other signaling pathways, such as AKT/mTOR, MEK or SRC, was relatively less effective. The combined treatment resulted in simultaneous attenuation of multiple survival pathways and increased inhibition of ERK pathway. In addition, the dual inhibition showed a stronger suppression of xenograft tumor growth than either single inhibition.

Conclusions: Our findings demonstrate that feedback activation of STAT3 pathway might contribute to the resistance to EGFR inhibition. Combined blockade of both pathways appears to be more effective against human ovarian cancer than inhibition of each pathway alone both in vitro and in vivo. This study may provide a strategy to improve clinical benefit of targeting EGFR pathway in ovarian cancer patients.
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http://dx.doi.org/10.1186/s12943-015-0366-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4437681PMC
May 2015

Revisiting STAT3 signalling in cancer: new and unexpected biological functions.

Nat Rev Cancer 2014 Nov;14(11):736-46

Vaccine and Gene Therapy Institute of Florida, Port St. Lucie, Florida 34987, USA.

The Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) proteins, particularly STAT3, are among the most promising new targets for cancer therapy. In addition to interleukin-6 (IL-6) and its family members, multiple pathways, including G-protein-coupled receptors (GPCRs), Toll-like receptors (TLRs) and microRNAs were recently identified to regulate JAK-STAT signalling in cancer. Well known for its role in tumour cell proliferation, survival, invasion and immunosuppression, JAK-STAT3 signalling also promotes cancer through inflammation, obesity, stem cells and the pre-metastatic niche. In addition to its established role as a transcription factor in cancer, STAT3 regulates mitochondrion functions, as well as gene expression through epigenetic mechanisms. Newly identified regulators and functions of JAK-STAT3 in tumours are important targets for potential therapeutic strategies in the treatment of cancer.
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http://dx.doi.org/10.1038/nrc3818DOI Listing
November 2014

Targeting JAK1/STAT3 signaling suppresses tumor progression and metastasis in a peritoneal model of human ovarian cancer.

Mol Cancer Ther 2014 Dec 15;13(12):3037-48. Epub 2014 Oct 15.

Department of Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, California.

JAK/STAT3 is one of the major signaling pathways that is aberrantly activated in ovarian cancer and associated with tumor progression and poor prognosis in patients with ovarian cancer. In this study, we evaluated the therapeutic potential of targeting JAK/STAT3 signaling in ovarian cancer using a peritoneal dissemination mouse model. We developed this mouse model by injecting a metastatic human ovarian cancer cell line, SKOV3-M-Luc, into the peritoneal cavity of immunodeficient mice. This model displayed a phenotype similar to late-stage ovarian cancer, including extensive peritoneal metastasis and ascites production. The constitutive activation of STAT3 in human ovarian cancer cells appeared to be mediated by an autocrine cytokine loop involving the IL6 family of cytokines and JAK1 kinase. shRNA-mediated knockdown of JAK1 or STAT3 in ovarian cancer cells led to reduced tumor growth, decreased peritoneal dissemination, and diminished ascites production, suggesting a critical role of STAT3 in ovarian cancer progression. Similar results were obtained when a small-molecule inhibitor (JAKi) of the JAK1 kinase was used to treat ovarian cancer in this model. In addition, we found that the expression level of IL6 was correlated with activation of STAT3 in ovarian cancer cells both in vitro and in vivo, suggesting a potential application of IL6 as a biomarker. Altogether, our results demonstrate that targeting JAK1/STAT3, using shRNA knockdown or a small-molecule inhibitor, effectively suppressed ovarian tumor progression and, therefore, could be a potential novel therapeutic approach for treating advanced ovarian cancer.
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http://dx.doi.org/10.1158/1535-7163.MCT-14-0077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321961PMC
December 2014

TLR9 is critical for glioma stem cell maintenance and targeting.

Cancer Res 2014 Sep 21;74(18):5218-28. Epub 2014 Jul 21.

Department of Cancer Immunotherapeutics and Tumor Immunology, Beckman Research Institute at City of Hope Medical Center, Duarte, California. Center for Translational Medicine, Shanghai Zhangjiang High-Tech Park, Shanghai, China.

Understanding supports for cancer stem-like cells in malignant glioma may suggest therapeutic strategies for their elimination. Here, we show that the Toll-like receptor TLR9 is elevated in glioma stem-like cells (GSC) in which it contributes to glioma growth. TLR9 overexpression is regulated by STAT3, which is required for GSC maintenance. Stimulation of TLR9 with a CpG ligand (CpG ODN) promoted GSC growth, whereas silencing TLR9 expression abrogated GSC development. CpG-ODN treatment induced Frizzled4-dependent activation of JAK2, thereby activating STAT3. Targeted delivery of siRNA into GSC was achieved via TLR9 using CpG-siRNA conjugates. Through local or systemic treatment, administration of CpG-Stat3 siRNA to silence STAT3 in vivo reduced GSC along with glioma growth. Our findings identify TLR9 as a functional marker for GSC and a target for the delivery of efficacious therapeutics for glioma treatment. Cancer Res; 74(18); 5218-28. ©2014 AACR.
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http://dx.doi.org/10.1158/0008-5472.CAN-14-1151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4167470PMC
September 2014

A novel berbamine derivative inhibits cell viability and induces apoptosis in cancer stem-like cells of human glioblastoma, via up-regulation of miRNA-4284 and JNK/AP-1 signaling.

PLoS One 2014 14;9(4):e94443. Epub 2014 Apr 14.

Translational Biomarker Discovery Core, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, California, United States of America; Molecular Pharmacology, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, California, United States of America.

Glioblastoma (GBM) is the most common primary brain tumor, accounting for approximately 40% of all central nervous system malignancies. Despite standard treatment consisting of surgical resection, radiotherapy and/or chemotherapy, the prognosis for GBM is poor; with a median survival of 14.6 months. The cancer stem cell or cancer-initiating cell model has provided a new paradigm for understanding development and recurrence of GBM following treatment. Berbamine (BBM) is a natural compound derived from the Berberis amurensis plant, and along with its derivatives, has been shown to exhibit antitumor activity in several cancers. Here, we reported that a novel synthetic Berbamine derivative, BBMD3, inhibits cell viability and induces apoptosis of cancer stem-like cells (CSCs) in a time- and dose-dependent manner when the CSCs from four GBM patients (PBT003, PBT008, PBT022, and PBT030) were cultured. These CSCs grew in neurospheres and expressed CD133 and nestin as markers. Treatment with BBMD3 destroyed the neurosphere morphology, and led to the induction of apoptosis in the CSCs. Induction of apoptosis in these CSCs is dependent upon activation of caspase-3 and cleavage of poly (ADP-ribose) polymerase (PARP). MicroRNA-4284 (miR-4284) was shown to be over-expressed about 4-fold in the CSCs following BBMD3 treatment. Furthermore, transfection of synthetic anti-sense oligonucleotide against human miR-4284 partially blocked the anticancer effects of BBMD3 on the GBM derived CSCs. BBMD3 also increased phosphorylation of the c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK), resulting in an increase expression of phosphorylated c-Jun and total c-Fos; the major components of transcriptional factor AP-1. The JNK-c-Jun/AP-1 signaling pathway plays an important role in the induction of apoptosis in response to UV irradiation and some drug treatments. Targeting glioblastoma stem-like cells with BBMD3 is therefore novel, and may have promise as an effective therapeutic strategy for treating GBM patients.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0094443PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3986211PMC
January 2015

Role of altered growth factor receptor-mediated JAK2 signaling in growth and maintenance of human acute myeloid leukemia stem cells.

Blood 2014 May 25;123(18):2826-37. Epub 2014 Mar 25.

Division of Hematopoietic Stem Cell and Leukemia Research.

Acute myeloid leukemia (AML) is sustained by small populations of leukemia stem cells (LSCs) that can resist available treatments and represent important barriers to cure. Although previous studies have shown increased signal transducer and activator of transcription (STAT)3 and STAT5 phosphorylation in AML leukemic blasts, the role of Janus kinase (JAK) signaling in primary AML compared with normal stem cells has not been directly evaluated. We show here that JAK/STAT signaling is increased in LSCs, particularly from high-risk AML. JAK2 inhibition using small molecule inhibitors or interference RNA reduced growth of AML LSCs while sparing normal stem cells both in vitro and in vivo. Increased JAK/STAT activity was associated with increased expression and altered signaling through growth factor receptors in AML LSCs, including receptor tyrosine kinase c-KIT and FMS-related tyrosine kinase 3 (FLT3). Inhibition of c-KIT and FLT3 expression significantly inhibited JAK/STAT signaling in AML LSCs, and JAK inhibitors effectively inhibited FLT3-mutated AML LSCs. Our results indicate that JAK/STAT signaling represents an important signaling mechanism supporting AML LSC growth and survival. These studies support continued evaluation of strategies for JAK/STAT inhibition for therapeutic targeting of AML LSCs.
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http://dx.doi.org/10.1182/blood-2013-05-505735DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4007609PMC
May 2014

Loss of androgen receptor expression promotes a stem-like cell phenotype in prostate cancer through STAT3 signaling.

Cancer Res 2014 Feb 31;74(4):1227-37. Epub 2013 Oct 31.

Authors' Affiliations: Departments of Molecular Medicine, Cancer Immunotherapy and Tumor Immunology, and Medical Oncology, Beckman Research Institute and City of Hope Comprehensive Cancer Center, Duarte, California; and Institute for Biochemistry and Molecular Biology, Universitätsklinikum RWTH Aachen, Aachen, Germany.

Androgen receptor (AR) signaling is important for prostate cancer progression. However, androgen-deprivation and/or AR targeting-based therapies often lead to resistance. Here, we demonstrate that loss of AR expression results in STAT3 activation in prostate cancer cells. AR downregulation further leads to development of prostate cancer stem-like cells (CSC), which requires STAT3. In human prostate tumor tissues, elevated cancer stem-like cell markers coincide with those cells exhibiting high STAT3 activity and low AR expression. AR downregulation-induced STAT3 activation is mediated through increased interleukin (IL)-6 expression. Treating mice with soluble IL-6 receptor fusion protein or silencing STAT3 in tumor cells significantly reduced prostate tumor growth and CSCs. Together, these findings indicate an opposing role of AR and STAT3 in prostate CSC development.
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http://dx.doi.org/10.1158/0008-5472.CAN-13-0594DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539262PMC
February 2014

MLS-2384, a new 6-bromoindirubin derivative with dual JAK/Src kinase inhibitory activity, suppresses growth of diverse cancer cells.

Cancer Biol Ther 2014 Feb 1;15(2):178-84. Epub 2013 Nov 1.

Vaccine & Gene Therapy Institute of Florida; Port St. Lucie, FL USA.

Janus kinase (JAK) and Src kinase are the two major tyrosine kinase families upstream of signal transducer and activator of transcription (STAT). Among the seven STAT family proteins, STAT3 is constitutively activated in many diverse cancers. Upon activation, JAK and Src kinases phosphorylate STAT3, and thereby promote cell growth and survival. MLS-2384 is a novel 6-bromoindirubin derivative with a bromo-group at the 6-position on one indole ring and a hydrophilic group at the 3'-position on the other indole ring. In this study, we investigated the kinase inhibitory activity and anticancer activity of MLS-2384. Our data from in vitro kinase assays, cell viability analyses, western blotting analyses, and animal model studies, demonstrate that MLS-2384 is a dual JAK/Src kinase inhibitor, and suppresses growth of various human cancer cells, such as prostate, breast, skin, ovarian, lung, and liver. Consistent with the inactivation of JAK and Src kinases, phosphorylation of STAT3 was inhibited in a dose-dependent manner in the cancer cells treated with MLS-2384. STAT3 downstream proteins involved in cell proliferation and survival, such as c-Myc and Mcl-1, are downregulated by MLS-2384 in prostate cancer cells, whereas survivin is downregulated in A2058 cells. In these two cancer cell lines, PARP is cleaved, indicating that MLS-2384 induces apoptosis in human melanoma and prostate cancer cells. Importantly, MLS-2384 suppresses tumor growth with low toxicity in a mouse xenograft model of human melanoma. Taken together, MLS-2384 demonstrates dual JAK/Src inhibitory activity and suppresses tumor cell growth both in vitro and in vivo. Our findings support further development of MLS-2384 as a potential small-molecule therapeutic agent that targets JAK, Src, and STAT3 signaling in multiple human cancer cells.
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http://dx.doi.org/10.4161/cbt.26721DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3928133PMC
February 2014

A novel synthetic derivative of the natural product berbamine inhibits cell viability and induces apoptosis of human osteosarcoma cells, associated with activation of JNK/AP-1 signaling.

Cancer Biol Ther 2013 Nov 28;14(11):1024-31. Epub 2013 Aug 28.

Department of Molecular Medicine; Beckman Research Institute; City of Hope Comprehensive Cancer Center; Duarte, CA USA.

Osteosarcoma is the most common primary bone tumor in children and adolescents. There is a critical need to find more potent drugs for patients with metastatic or recurrent disease. Berbamine (BBM) is a natural compound derived from the Berberis amurensis plants. BBM and its derivatives have been shown to have antitumor effects in several cancers. Here, we report that a novel synthetic berbamine derivative, BBMD3, inhibits cell viability and induces apoptosis of G292, KHOS, and MG-63 human osteosarcoma cells. Induction of apoptosis in these tumor cells depends on activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase (PARP). Since pan-caspase inhibitor (Z-VAD-FMK) and caspase-9 inhibitor (Z-LEHD-FMK) could block the cleavage of PARP, the apoptosis induced by BBMD3 is through intrinsic signaling pathway. BBMD3 increased phosphorylation of c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK), resulting in increase of phosphorylated c-Jun and total c-Fos, the major components of transcriptional factor AP-1. JNK inhibitor could partially suppress antitumor effect of BBMD3 on osteosarcoma cells. BBMD3 increased the production of reactive oxygen species (ROS) and ROS scavenger, N-acetylcysteine (NAC), could block the phosphorylation of JNK and c-Jun induced by BBMD3. BBMD3 increased the expression of the pro-apototic gene Bad, associated with apoptosis induction. Finally, BBMD3 also decreased the expression of cyclin D1 and D2, the positive cell cycle regulators, which is correlated with growth inhibition in osteosarcoma cells. Collectively, these findings indicate that BBMD3 is a potentially promising drug for the treatment of human osteosarcoma.
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http://dx.doi.org/10.4161/cbt.26045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3925657PMC
November 2013

3-O-methylthespesilactam, a new small-molecule anticancer pan-JAK inhibitor against A2058 human melanoma cells.

Biochem Pharmacol 2013 Nov 7;86(10):1411-8. Epub 2013 Sep 7.

Marine Drugs Research Center, College of Pharmacy, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, PR China.

Natural product-inspired discovery of new drug leads plays a key role in drug development. Recently, small-molecule JAK inhibitors have been pursued for the development of anticancer therapeutics. However, most of these inhibitors reported up to now are multi-nitrogen polycyclic aromatic heterocycles. Undoubtedly, the discovery of new types of promising JAK-inhibitory leads is pivotal for JAK inhibitor-based anticancer drug development. Herein we report an unprecedented sesquiterpenoid-alkaloid named thespesilactam, containing a benzo[cd]indole scaffold, from the heartwood of the Portia tree, Thespesia populnea. Its 3-O-Me product, i.e. 8-hydroxy-5-isopropyl-3-methoxy-7-methylbenzo[cd]indol-2(1H)-one, named 3-O-methylthespesilactam, of which the structure was identified by NMR investigations and single-crystal X-ray diffraction analysis, was discovered as a new type of small-molecule anticancer pan-JAK inhibitor against A2058 human melanoma cells, and selective and potent inhibitor of JAK1 and TYK2.
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http://dx.doi.org/10.1016/j.bcp.2013.08.065DOI Listing
November 2013

Regulation of adipose tissue T cell subsets by Stat3 is crucial for diet-induced obesity and insulin resistance.

Proc Natl Acad Sci U S A 2013 Aug 22;110(32):13079-84. Epub 2013 Jul 22.

Department of Cancer Immunotherapeutics and Tumor Immunology, Beckman Research Institute, Duarte, CA 91010, USA.

Dysregulated inflammation in adipose tissue, marked by increased proinflammatory T-cell accumulation and reduced regulatory T cells (Tregs), contributes to obesity-associated insulin resistance. The molecular mechanisms underlying T-cell-mediated inflammation in adipose tissue remain largely unknown, however. Here we show a crucial role for signal transducer and activator of transcription 3 (Stat3) in T cells in skewing adaptive immunity in visceral adipose tissue (VAT), thereby contributing to diet-induced obesity (DIO) and insulin resistance. Stat3 activity is elevated in obese VAT and in VAT-resident T cells. Functional ablation of Stat3 in T cells reduces DIO, improves insulin sensitivity and glucose tolerance, and suppresses VAT inflammation. Importantly, Stat3 ablation reverses the high Th1/Treg ratio in VAT of DIO mice that is likely secondary to elevated IL-6 production, leading in turn to suppression of Tregs. In addition, Stat3 in T cells in DIO mice affects adipose tissue macrophage accumulation and M2 phenotype. Our study identifies Stat3 in VAT-resident T cells as an important mediator and direct target for regulating adipose tissue inflammation, DIO, and its associated metabolic dysfunctions.
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http://dx.doi.org/10.1073/pnas.1311557110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3740863PMC
August 2013

Critical role of STAT3 in IL-6-mediated drug resistance in human neuroblastoma.

Cancer Res 2013 Jul 30;73(13):3852-64. Epub 2013 Apr 30.

Division of Hematology-Oncology, Department of Pediatrics, Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.

Drug resistance is a major cause of treatment failure in cancer. Here, we have evaluated the role of STAT3 in environment-mediated drug resistance (EMDR) in human neuroblastoma. We determined that STAT3 was not constitutively active in most neuroblastoma cell lines but was rapidly activated upon treatment with interleukin (IL)-6 alone and in combination with the soluble IL-6 receptor (sIL-6R). Treatment of neuroblastoma cells with IL-6 protected them from drug-induced apoptosis in a STAT3-dependent manner because the protective effect of IL-6 was abrogated in the presence of a STAT3 inhibitor and upon STAT3 knockdown. STAT3 was necessary for the upregulation of several survival factors such as survivin (BIRC5) and Bcl-xL (BCL2L1) when cells were exposed to IL-6. Importantly, IL-6-mediated STAT3 activation was enhanced by sIL-6R produced by human monocytes, pointing to an important function of monocytes in promoting IL-6-mediated EMDR. Our data also point to the presence of reciprocal activation of STAT3 between tumor cells and bone marrow stromal cells including not only monocytes but also regulatory T cells (Treg) and nonmyeloid stromal cells. Thus, the data identify an IL-6/sIL-6R/STAT3 interactive pathway between neuroblastoma cells and their microenvironment that contributes to drug resistance.
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http://dx.doi.org/10.1158/0008-5472.CAN-12-2353DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3740971PMC
July 2013