Publications by authors named "Sebastien Tabariès"

21 Publications

  • Page 1 of 1

Afadin (AF6) in cancer progression: A multidomain scaffold protein with complex and contradictory roles.

Bioessays 2021 Jan 9;43(1):e2000221. Epub 2020 Nov 9.

Goodman Cancer Research Centre, McGill University, Montréal, Québec, Canada.

Adherens (AJ) and tight junctions (TJ) maintain cell-cell adhesions and cellular polarity in normal tissues. Afadin, a multi-domain scaffold protein, is commonly found in both adherens and tight junctions, where it plays both structural and signal-modulating roles. Afadin is a complex modulator of cellular processes implicated in cancer progression, including signal transduction, migration, invasion, and apoptosis. In keeping with the complexities associated with the roles of adherens and tight junctions in cancer, afadin exhibits both tumor suppressive and pro-metastatic functions. In this review, we will explore the dichotomous roles that afadin plays during cancer progression.
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http://dx.doi.org/10.1002/bies.202000221DOI Listing
January 2021

C3a elicits unique migratory responses in immature low-density neutrophils.

Oncogene 2020 03 4;39(12):2612-2623. Epub 2020 Feb 4.

Goodman Cancer Research Centre, McGill University, Montréal, QC, H3A 1A3, Canada.

Neutrophils represent the immune system's first line of defense and are rapidly recruited into inflamed tissue. In cancer associated inflammation, phenotypic heterogeneity has been ascribed to this cell type, whereby neutrophils can manifest anti- or pro-metastatic functions depending on the cellular/micro-environmental context. Here, we demonstrate that pro-metastatic immature low-density neutrophils (iLDNs) more efficiently accumulate in the livers of mice bearing metastatic lesions compared with anti-metastatic mature high-density neutrophils (HDNs). Transcriptomic analyses reveal enrichment of a migration signature in iLDNs relative to HDNs. We find that conditioned media derived from liver-metastatic breast cancer cells, but not lung-metastatic variants, specifically induces chemotaxis of iLDNs and not HDNs. Chemotactic responses are due to increased surface expression of C3aR in iLDNs relative to HDNs. In addition, we detect elevated secretion of cancer-cell derived C3a from liver-metastatic versus lung-metastatic breast cancer cells. Perturbation of C3a/C3aR signaling axis with either a small molecule inhibitor, SB290157, or reducing the levels of secreted C3a from liver-metastatic breast cancer cells by short hairpin RNAs, can abrogate the chemotactic response of iLDNs both in vitro and in vivo, respectively. Together, these data reveal novel mechanisms through which iLDNs prefentially accumulate in liver tissue harboring metastases in response to tumor-derived C3a secreted from the liver-aggressive 4T1 breast cancer cells.
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http://dx.doi.org/10.1038/s41388-020-1169-8DOI Listing
March 2020

p66ShcA functions as a contextual promoter of breast cancer metastasis.

Breast Cancer Res 2020 01 15;22(1). Epub 2020 Jan 15.

Lady Davis Institute for Medical Research, 3755 Chemin de la Côte-Sainte-Catherine, Montreal, QC, H3T 1E2, Canada.

Background: The p66ShcA redox protein is the longest isoform of the Shc1 gene and is variably expressed in breast cancers. In response to a variety of stress stimuli, p66ShcA becomes phosphorylated on serine 36, which allows it to translocate from the cytoplasm to the mitochondria where it stimulates the formation of reactive oxygen species (ROS). Conflicting studies suggest both pro- and anti-tumorigenic functions for p66ShcA, which prompted us to examine the contribution of tumor cell-intrinsic functions of p66ShcA during breast cancer metastasis.

Methods: We tested whether p66ShcA impacts the lung-metastatic ability of breast cancer cells. Breast cancer cells characteristic of the ErbB2+/luminal (NIC) or basal (4T1) subtypes were engineered to overexpress p66ShcA. In addition, lung-metastatic 4T1 variants (4T1-537) were engineered to lack endogenous p66ShcA via Crispr/Cas9 genomic editing. p66ShcA null cells were then reconstituted with wild-type p66ShcA or a mutant (S36A) that cannot translocate to the mitochondria, thereby lacking the ability to stimulate mitochondrial-dependent ROS production. These cells were tested for their ability to form spontaneous metastases from the primary site or seed and colonize the lung in experimental (tail vein) metastasis assays. These cells were further characterized with respect to their migration rates, focal adhesion dynamics, and resistance to anoikis in vitro. Finally, their ability to survive in circulation and seed the lungs of mice was assessed in vivo.

Results: We show that p66ShcA increases the lung-metastatic potential of breast cancer cells by augmenting their ability to navigate each stage of the metastatic cascade. A non-phosphorylatable p66ShcA-S36A mutant, which cannot translocate to the mitochondria, still potentiated breast cancer cell migration, lung colonization, and growth of secondary lung metastases. However, breast cancer cell survival in the circulation uniquely required an intact p66ShcA S36 phosphorylation site.

Conclusion: This study provides the first evidence that both mitochondrial and non-mitochondrial p66ShcA pools collaborate in breast cancer cells to promote their maximal metastatic fitness.
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http://dx.doi.org/10.1186/s13058-020-1245-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6964019PMC
January 2020

Dipeptidase-1 Is an Adhesion Receptor for Neutrophil Recruitment in Lungs and Liver.

Cell 2019 08;178(5):1205-1221.e17

Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Oncology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada. Electronic address:

A hallmark feature of inflammation is the orchestrated recruitment of neutrophils from the bloodstream into inflamed tissue. Although selectins and integrins mediate recruitment in many tissues, they have a minimal role in the lungs and liver. Exploiting an unbiased in vivo functional screen, we identified a lung and liver homing peptide that functionally abrogates neutrophil recruitment to these organs. Using biochemical, genetic, and confocal intravital imaging approaches, we identified dipeptidase-1 (DPEP1) as the target and established its role as a physical adhesion receptor for neutrophil sequestration independent of its enzymatic activity. Importantly, genetic ablation or functional peptide blocking of DPEP1 significantly reduced neutrophil recruitment to the lungs and liver and provided improved survival in models of endotoxemia. Our data establish DPEP1 as a major adhesion receptor on the lung and liver endothelium and identify a therapeutic target for neutrophil-driven inflammatory diseases of the lungs.
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http://dx.doi.org/10.1016/j.cell.2019.07.017DOI Listing
August 2019

Immature Low-Density Neutrophils Exhibit Metabolic Flexibility that Facilitates Breast Cancer Liver Metastasis.

Cell Rep 2019 06;27(13):3902-3915.e6

Goodman Cancer Research Centre, McGill University, Montreal, Québec, QC H3A 1A3, Canada; Department of Medicine, McGill University, Montreal, Québec, QC H3G 1Y6, Canada. Electronic address:

Neutrophils are phenotypically heterogeneous and exert either anti- or pro-metastatic functions. We show that cancer-cell-derived G-CSF is necessary, but not sufficient, to mobilize immature low-density neutrophils (iLDNs) that promote liver metastasis. In contrast, mature high-density neutrophils inhibit the formation of liver metastases. Transcriptomic and metabolomic analyses of high- and low-density neutrophils reveal engagement of numerous metabolic pathways specifically in low-density neutrophils. iLDNs exhibit enhanced global bioenergetic capacity, through their ability to engage mitochondrial-dependent ATP production, and remain capable of executing pro-metastatic neutrophil functions, including NETosis, under nutrient-deprived conditions. We demonstrate that NETosis is an important neutrophil function that promotes breast cancer liver metastasis. iLDNs rely on the catabolism of glutamate and proline to support mitochondrial-dependent metabolism in the absence of glucose, which enables sustained NETosis. These data reveal that distinct pro-metastatic neutrophil populations exhibit a high degree of metabolic flexibility, which facilitates the formation of liver metastases.
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http://dx.doi.org/10.1016/j.celrep.2019.05.091DOI Listing
June 2019

Afadin cooperates with Claudin-2 to promote breast cancer metastasis.

Genes Dev 2019 02 28;33(3-4):180-193. Epub 2019 Jan 28.

Goodman Cancer Research Centre, McGill University, Montréal, Québec H3A 1A3, Canada.

Claudin-2 promotes breast cancer liver metastasis by enabling seeding and early cancer cell survival. We now demonstrate that the PDZ-binding motif of Claudin-2 is necessary for anchorage-independent growth of cancer cells and is required for liver metastasis. Several PDZ domain-containing proteins were identified that interact with the PDZ-binding motif of Claudin-2 in liver metastatic breast cancer cells, including Afadin, Arhgap21, Pdlim2, Pdlim7, Rims2, Scrib, and ZO-1. We specifically examined the role of Afadin as a potential Claudin-2-interacting partner that promotes breast cancer liver metastasis. Afadin associates with Claudin-2, an interaction that requires the PDZ-binding motif of Claudin-2. Loss of Afadin also impairs the ability of breast cancer cells to form colonies in soft agar and metastasize to the lungs or liver. Immunohistochemical analysis of Claudin-2 and/or Afadin expression in 206 metastatic breast cancer tumors revealed that high levels of both Claudin-2 and Afadin in primary tumors were associated with poor disease-specific survival, relapse-free survival, lung-specific relapse, and liver-specific relapse. Our findings indicate that signaling downstream from a Claudin-2/Afadin complex enables the efficient formation of breast cancer metastases. Moreover, combining Claudin-2 and Afadin as prognostic markers better predicts the potential of breast cancer to metastasize to soft tissues.
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http://dx.doi.org/10.1101/gad.319194.118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362814PMC
February 2019

Exosomal Release of L-Plastin by Breast Cancer Cells Facilitates Metastatic Bone Osteolysis.

Transl Oncol 2019 Mar 21;12(3):462-474. Epub 2018 Dec 21.

Faculty of Dentistry, McGill University, 3640 rue University, Montreal, Quebec, Canada, H3A 0C7; Shriner's Hospital for Children - Canada, 1003 Decarie Boulevard, Montreal, Quebec H4A 0A9. Electronic address:

Bone metastasis from breast and prostate carcinomas is facilitated by activation of bone-resorbing osteoclasts. Using proteomics approaches, we have identified peroxiredoxin-4 (PRDX4) as a cancer-secreted mediator of osteoclastogenesis. We now report characterization of L-plastin in the conditioned media (CM) of MDA-MB-231 human breast cancer cells using immunoblotting and mass spectrometry. The osteoclastogenic potential of MDA-MB-231 CM with siRNA-silenced L-plastin was significantly reduced. L-plastin was detected in cancer-derived exosomes, and inhibition of exosomal release significantly decreased the osteoclastogenic capacity of MDA-MB-231 CM. When added to osteoclast precursors primed with RANKL for 2 days, recombinant L-plastin induced calcium/NFATc1-mediated osteoclastogenesis to the levels similar to continuous treatment with RANKL. Using shRNA, we generated MDA-MB-231 cells lacking L-plastin, PRDX4, or both and injected these cell populations intratibially in CD-1 immunodeficient mice. Micro-CT and histomorphometric analysis demonstrated a complete loss of osteolysis when MDA-MB-231 cells lacking both L-plastin and PRDX4 were injected. A meta-analysis established an increase in L-plastin and PRDX4 mRNA expression in numerous human cancers, including breast and prostate carcinomas. This study demonstrates that secreted L-plastin and PRDX4 mediate osteoclast activation by human breast cancer cells.
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http://dx.doi.org/10.1016/j.tranon.2018.11.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6305809PMC
March 2019

PGC-1α Promotes Breast Cancer Metastasis and Confers Bioenergetic Flexibility against Metabolic Drugs.

Cell Metab 2017 Nov 5;26(5):778-787.e5. Epub 2017 Oct 5.

Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; Goodman Cancer Research Centre, McGill University, Montreal, QC H3G 1Y6, Canada. Electronic address:

Metabolic adaptations play a key role in fueling tumor growth. However, less is known regarding the metabolic changes that promote cancer progression to metastatic disease. Herein, we reveal that breast cancer cells that preferentially metastasize to the lung or bone display relatively high expression of PGC-1α compared with those that metastasize to the liver. PGC-1α promotes breast cancer cell migration and invasion in vitro and augments lung metastasis in vivo. Pro-metastatic capabilities of PGC-1α are linked to enhanced global bioenergetic capacity, facilitating the ability to cope with bioenergetic disruptors like biguanides. Indeed, biguanides fail to mitigate the PGC-1α-dependent lung metastatic phenotype and PGC-1α confers resistance to stepwise increases in metformin concentration. Overall, our results reveal that PGC-1α stimulates bioenergetic potential, which promotes breast cancer metastasis and facilitates adaptation to metabolic drugs.
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http://dx.doi.org/10.1016/j.cmet.2017.09.006DOI Listing
November 2017

Intra-tumor delivery of zoledronate mitigates metastasis-induced osteolysis superior to systemic administration.

J Bone Oncol 2017 Mar 13;6:8-15. Epub 2017 Jan 13.

Division of Orthopaedic Surgery, Department of Surgery, McGill University, Montreal, Québec, Canada.

Bisphosphonates (BPs) have recently been shown to have direct anti-tumor properties. Systemic treatment with BPs can have multiple adverse effects such as osteonecrosis of the jaw and BP induced bone fracturing and spine instability. While benefits of systemic BP treatments may outweigh risks, local treatment with BPs has been explored as an alternate strategy to reduce unwarranted risk. In the present study, we examined whether local delivery of BPs inhibits tumor-induced osteolysis and tumor growth more effectively than systemic treatment in an animal model of tumor-induced bone disease. Following establishment of an intra-tibial model of bone metastases in athymic mice, the experimental group was treated by local administration of zoledronate into the tibial lesion. A comparison of the effect of local versus systemic delivery of zoledronate on the formation of tumor-induced osteolysis was also carried out. A significant increase in mean bone volume/tissue volume % (BV/TV) of the locally treated group (12.30±2.80%) compared to the control group (7.13±1.22%) (<0.001). Additionally, there was a significant increase in the BV/TV (10.90±1.25%) in the locally treated group compared to the systemically treated group (7.53±0.75%) (=0.005). These preliminary results suggest that local delivery of BPs outperforms both systemic and control treatments to inhibit tumor-induced osteolysis.
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http://dx.doi.org/10.1016/j.jbo.2017.01.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5262502PMC
March 2017

The histone H3K9 demethylase KDM3A promotes anoikis by transcriptionally activating pro-apoptotic genes BNIP3 and BNIP3L.

Elife 2016 07 29;5. Epub 2016 Jul 29.

Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States.

Epithelial cells that lose attachment to the extracellular matrix undergo a specialized form of apoptosis called anoikis. Here, using large-scale RNA interference (RNAi) screening, we find that KDM3A, a histone H3 lysine 9 (H3K9) mono- and di-demethylase, plays a pivotal role in anoikis induction. In attached breast epithelial cells, KDM3A expression is maintained at low levels by integrin signaling. Following detachment, integrin signaling is decreased resulting in increased KDM3A expression. RNAi-mediated knockdown of KDM3A substantially reduces apoptosis following detachment and, conversely, ectopic expression of KDM3A induces cell death in attached cells. We find that KDM3A promotes anoikis through transcriptional activation of BNIP3 and BNIP3L, which encode pro-apoptotic proteins. Using mouse models of breast cancer metastasis we show that knockdown of Kdm3a enhances metastatic potential. Finally, we find defective KDM3A expression in human breast cancer cell lines and tumors. Collectively, our results reveal a novel transcriptional regulatory program that mediates anoikis.
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http://dx.doi.org/10.7554/eLife.16844DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4991936PMC
July 2016

Chordin-Like 1 Suppresses Bone Morphogenetic Protein 4-Induced Breast Cancer Cell Migration and Invasion.

Mol Cell Biol 2016 05 2;36(10):1509-25. Epub 2016 May 2.

Goodman Cancer Research Centre, McGill University, Montréal, Québec, Canada Department of Biochemistry, McGill University, Montréal, Québec, Canada Department of Medicine, McGill University, Montréal, Québec, Canada

ShcA is an important mediator of ErbB2- and transforming growth factor β (TGF-β)-induced breast cancer cell migration, invasion, and metastasis. We show that in the context of reduced ShcA levels, the bone morphogenetic protein (BMP) antagonist chordin-like 1 (Chrdl1) is upregulated in numerous breast cancer cells following TGF-β stimulation. BMPs have emerged as important modulators of breast cancer aggressiveness, and we have investigated the ability of Chrdl1 to block BMP-induced increases in breast cancer cell migration and invasion. Breast cancer-derived conditioned medium containing elevated concentrations of endogenous Chrdl1, as well as medium containing recombinant Chrdl1, suppresses BMP4-induced signaling in multiple breast cancer cell lines. Live-cell migration assays reveal that BMP4 induces breast cancer migration, which is effectively blocked by Chrdl1. We demonstrate that BMP4 also stimulated breast cancer cell invasion and matrix degradation, in part, through enhanced metalloproteinase 2 (MMP2) and MMP9 activity that is antagonized by Chrdl1. Finally, high Chrdl1 expression was associated with better clinical outcomes in patients with breast cancer. Together, our data reveal that Chrdl1 acts as a negative regulator of malignant breast cancer phenotypes through inhibition of BMP signaling.
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http://dx.doi.org/10.1128/MCB.00600-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4859683PMC
May 2016

Decreased PCSK9 expression in human hepatocellular carcinoma.

BMC Gastroenterol 2015 Dec 16;15:176. Epub 2015 Dec 16.

Department of Pathology, McGill University Health Centre, Montreal, QC, Canada.

Background: The management of hepatocellular carcinoma (HCC) is limited by the lack of adequate screening biomarkers and chemotherapy. In response, there has been much interest in tumor metabolism as a therapeutic target. PCSK9 stimulates internalization of the LDL-receptor, decreases cholesterol uptake into hepatocytes and affects liver regeneration. Thus, we investigated whether PCSK9 expression is altered in HCC, influencing its ability to harness cholesterol metabolism.

Methods: Thirty-nine patients undergoing partial hepatectomy or liver transplantation for HCC were consented for use of HCC tissue to construct a tissue microarray (TMA). The TMA was immunostained for PCSK9. Imagescope software was used to objectively determine staining, and assess for pathological and clinical correlations. PCSK9 and LDL receptor mRNA levels in flash-frozen HCC and adjacent liver tissue were determined by quantitative RT-PCR. Serum PCSK9 levels were determined by ELISA.

Results: By immunohistochemistry, there was significantly lower expression of PCSK9 in HCC as compared to adjacent cirrhosis (p-value < 0.0001, wilcoxon signed-rank test). Significantly greater staining of PCSK9 was present in cirrhosis compared to HCC (p value <0.0001), and positivity (percentage of positive cells) was significantly greater in cirrhosis compared to HCC (p-value < 0.0001). Conversely, significantly higher expression of LDL-R was present in HCC as compared to the adjacent cirrhosis (p-value < 0.0001). There was no significant correlation of PCSK9 staining with grade of tumor, but there were significant correlations between PCSK9 staining and stage of fibrosis, according to spearman correlation test. PCSK9 mRNA levels were relatively less abundant within HCC compared to adjacent liver tissue (p-value =0.08) and normal control tissue (p-value =0.02). In contrast, serum PCSK9 levels were significantly increased among patients with HCC compared to those with chronic liver disease without HCC (p-value =0.029). LDL receptor mRNA was consistantly greater in HCC when compared to normal control tissue (p-value = 0.06) and, in general, was significantly greater in HCC when compared to adjacent liver (p-value = 0.04).

Conclusions: The decreased expression of PCSK9 and conversely increased LDL-R expression in HCC suggests that HCC modulates its local microenvironment to enable a constant energy supply. Larger-scale studies should be conducted to determine whether PCSK9 could be a therapeutic target for HCC.
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http://dx.doi.org/10.1186/s12876-015-0371-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4682218PMC
December 2015

PDK1-Dependent Metabolic Reprogramming Dictates Metastatic Potential in Breast Cancer.

Cell Metab 2015 Oct 10;22(4):577-89. Epub 2015 Sep 10.

Goodman Cancer Research Centre, McGill University, Montréal, QC H3A 1A3, Canada; Department of Biochemistry, McGill University, Montréal, QC H3A 1A3, Canada; Department of Medicine, McGill University, Montréal, QC H3A 1A3, Canada. Electronic address:

Metabolic reprogramming is a hallmark of cellular transformation, yet little is known about metabolic changes that accompany tumor metastasis. Here we show that primary breast cancer cells display extensive metabolic heterogeneity and engage distinct metabolic programs depending on their site of metastasis. Liver-metastatic breast cancer cells exhibit a unique metabolic program compared to bone- or lung-metastatic cells, characterized by increased conversion of glucose-derived pyruvate into lactate and a concomitant reduction in mitochondrial metabolism. Liver-metastatic cells displayed increased HIF-1α activity and expression of the HIF-1α target Pyruvate dehydrogenase kinase-1 (PDK1). Silencing HIF-1α reversed the glycolytic phenotype of liver-metastatic cells, while PDK1 was specifically required for metabolic adaptation to nutrient limitation and hypoxia. Finally, we demonstrate that PDK1 is required for efficient liver metastasis, and its expression is elevated in liver metastases from breast cancer patients. Our data implicate PDK1 as a key regulator of metabolism and metastatic potential in breast cancer.
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http://dx.doi.org/10.1016/j.cmet.2015.08.007DOI Listing
October 2015

Granulocytic immune infiltrates are essential for the efficient formation of breast cancer liver metastases.

Breast Cancer Res 2015 Mar 27;17:45. Epub 2015 Mar 27.

Goodman Cancer Research Centre, McGill University, 1160 Pine Avenue West, Room 513, Montréal, QC, H3A 1A3, Canada.

Introduction: Breast cancer cells display preferences for specific metastatic sites including the bone, lung and liver. Metastasis is a complex process that relies, in part, on interactions between disseminated cancer cells and resident/infiltrating stromal cells that constitute the metastatic microenvironment. Distinct immune infiltrates can either impair the metastatic process or conversely, assist in the seeding, colonization and growth of disseminated cancer cells.

Methods: Using in vivo selection approaches, we previously isolated 4T1-derived breast cancer cells that preferentially metastasize to these organs and tissues. In this study, we examined whether the propensity of breast cancer cells to metastasize to the lung, liver or bone is associated with and dependent on distinct patterns of immune cell infiltration. Immunohistocytochemistry and immunohistofluorescence approaches were used to quantify innate immune cell infiltrates within distinct metastases and depletion of Gr1+ (Ly-6C and Ly-6G) or specifically Ly-6G+ cells was performed to functionally interrogate the role of Ly-6G+ infiltrates in promoting metastasis to these organs.

Results: We show that T lymphocytes (CD3+), myeloid-derived (Gr-1+) cells and neutrophils (Ly-6G+ or NE+) exhibit the most pronounced recruitment in lung and liver metastases, with markedly less recruitment within bone metastatic lesions. Interestingly, these infiltrating cell populations display different patterns of localization within soft tissue metastases. T lymphocytes and granulocytic immune infiltrates are localized around the periphery of liver metastases whereas they were dispersed throughout the lung metastases. Furthermore, Gr-1+ cell-depletion studies demonstrate that infiltrating myeloid-derived cells are essential for the formation of breast cancer liver metastases but dispensable for metastasis to the lung and bone. A specific role for the granulocytic component of the innate immune infiltrate was revealed through Ly-6G+ cell-depletion experiments, which resulted in significantly impaired formation of liver metastases. Finally, we demonstrate that the CD11b+/Ly-6G+ neutrophils that infiltrate and surround the liver metastases are polarized toward an N2 phenotype, which have previously been shown to enhance tumor growth and metastasis.

Conclusions: Our results demonstrate that the liver-metastatic potential of breast cancer cells is heavily reliant on interactions with infiltrating Ly-6G+ cells within the liver microenvironment.
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http://dx.doi.org/10.1186/s13058-015-0558-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4413545PMC
March 2015

Lyn modulates Claudin-2 expression and is a therapeutic target for breast cancer liver metastasis.

Oncotarget 2015 Apr;6(11):9476-87

Goodman Cancer Research Centre, McGill University, Montréal, Québec, Canada, H3A 1A3.

Claudin-2 enhances breast cancer liver metastasis and promotes the development of colorectal cancers. The objective of our current study is to define the regulatory mechanisms controlling Claudin-2 expression in breast cancer cells. We evaluated the effect of several Src Family Kinase (SFK) inhibitors or knockdown of individual SFK members on Claudin-2 expression in breast cancer cells. We also assessed the potential effects of pan-SFK and SFK-selective inhibitors on the formation of breast cancer liver metastases. This study reveals that pan inhibition of SFK signaling pathways significantly elevated Claudin-2 expression levels in breast cancer cells. In addition, our data demonstrate that pan-SFK inhibitors can enhance breast cancer metastasis to the liver. Knockdown of individual SFK members reveals that loss of Yes or Fyn induces Claudin-2 expression; whereas, diminished Lyn levels impairs Claudin-2 expression in breast cancer cells. The Lyn-selective kinase inhibitor, Bafetinib (INNO-406), acts to reduce Claudin-2 expression and suppress breast cancer liver metastasis. Our findings may have major clinical implications and advise against the treatment of breast cancer patients with broad-acting SFK inhibitors and support the use of Lyn-specific inhibitors.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4496232PMC
http://dx.doi.org/10.18632/oncotarget.3269DOI Listing
April 2015

Peroxiredoxin 4: a novel secreted mediator of cancer induced osteoclastogenesis.

Cancer Lett 2015 Jun 14;361(2):262-70. Epub 2015 Mar 14.

Department of Anatomy and Cell Biology, McGill University, Montréal, Quebec, Canada; Shriners Hospital for Children-Canada, Montréal, Quebec H3G IA6, Canada; Faculty of Dentistry, McGill University, Montréal, Quebec, Canada. Electronic address:

Bone is a common site of metastasis from breast and prostate carcinoma, where activation of bone resorbing osteoclasts is important for cancer progression. A large body of evidence indicates that soluble factors produced by the cancer cells act to promote osteoclast formation. Using mass spectrometry, we identified peroxiredoxin (PRDX) as a secreted mediator of cancer-induced osteoclastogenesis. Both breast (MCF7 and MDA-MB-231) and prostate (PC3 and LNCaP) carcinoma cells secreted PRDX4. PRDX4 knockdown using shRNA (shPRDX4) diminished PRDX4 secretion from MDA-MB-231 and PC3 cells and significantly decreased the ability of cancer-derived factors to induce osteoclast formation from late precursors in vitro. Tibial injection of shPRDX4 PC3 cells led to the development of significantly smaller osteolytic lesions characterized by significantly reduced osteoclast numbers compared to control PC3 cells. A meta-analysis demonstrated an increase in PRDX4 mRNA expression in carcinoma and metastatic breast and prostate tissues. Moreover, high expression of PRDX4 in the primary breast tumor was consistently associated with metastasis at 5 years. These data identify a novel function of secreted PRDX4 in mediating osteoclast activation by cancer cells.
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http://dx.doi.org/10.1016/j.canlet.2015.03.012DOI Listing
June 2015

The IGF-Trap: Novel Inhibitor of Carcinoma Growth and Metastasis.

Mol Cancer Ther 2015 Apr 11;14(4):982-93. Epub 2015 Feb 11.

Department of Surgery, McGill University Health Centre, McGill University, Montreal, Québec, Canada. Department of Medicine, McGill University Health Centre, McGill University, Montreal, Québec, Canada. Department of Oncology, McGill University Health Centre, McGill University, Montreal, Québec, Canada.

The IGFI receptor promotes malignant progression and has been recognized as a target for cancer therapy. Clinical trials with anti-IGFIR antibodies provided evidence of therapeutic efficacy but exposed limitations due in part to effects on, and the compensatory function of, the insulin receptor system. Here, we report on the production, characterization, and biologic activity of a novel, IGF-targeting protein (the IGF-Trap) comprising a soluble form of hIGFIR and the Fc portion of hIgG1. The IGF-Trap has a high affinity for hIGFI and hIGFII but low affinity for insulin, as revealed by surface plasmon resonance. It efficiently blocked IGFIR signaling in several carcinoma cell types and inhibited tumor cell proliferation, migration, and invasion in vitro. In vivo, the IGF-Trap showed favorable pharmacokinetic properties and could suppress the growth of established breast carcinoma tumors when administered therapeutically into tumor-bearing mice, improving disease-free survival. Moreover, IGF-Trap treatment markedly reduced experimental liver metastasis of colon and lung carcinoma cells, increasing tumor cell apoptosis and reducing angiogenesis. Finally, when compared with an anti-IGFIR antibody or IGF-binding protein-1 that were used at similar or higher concentrations, the IGF-Trap showed superior therapeutic efficacy to both inhibitors. Taken together, we have developed a targeted therapeutic molecule with highly potent anticancer effects that could address limitations of current IGFIR-targeting agents.
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http://dx.doi.org/10.1158/1535-7163.MCT-14-0751DOI Listing
April 2015

Claudin-2 promotes breast cancer liver metastasis by facilitating tumor cell interactions with hepatocytes.

Mol Cell Biol 2012 Aug 29;32(15):2979-91. Epub 2012 May 29.

Goodman Cancer Research Centre, McGill University, Montréal, Québec, Canada.

We previously identified claudin-2 as a functional mediator of breast cancer liver metastasis. We now confirm that claudin-2 levels are elevated in liver metastases, but not in skin metastases, compared to levels in their matched primary tumors in patients with breast cancer. Moreover, claudin-2 is specifically expressed in liver-metastatic breast cancer cells compared to populations derived from bone or lung metastases. The increased liver tropism exhibited by claudin-2-expressing breast cancer cells requires claudin-2-mediated interactions between breast cancer cells and primary hepatocytes. Furthermore, the reduction of the claudin-2 expression level, either in cancer cells or in primary hepatocytes, diminishes these heterotypic cell-cell interactions. Finally, we demonstrate that the first claudin-2 extracellular loop is essential for mediating tumor cell-hepatocyte interactions and the ability of breast cancer cells to form liver metastases in vivo. Thus, during breast cancer liver metastasis, claudin-2 shifts from acting within tight-junctional complexes to functioning as an adhesion molecule between breast cancer cells and hepatocytes.
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http://dx.doi.org/10.1128/MCB.00299-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3434516PMC
August 2012

Multiple promoters and alternative splicing: Hoxa5 transcriptional complexity in the mouse embryo.

PLoS One 2010 May 12;5(5):e10600. Epub 2010 May 12.

Centre de recherche en cancérologie de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, Québec, Canada.

Background: The genomic organization of Hox clusters is fundamental for the precise spatio-temporal regulation and the function of each Hox gene, and hence for correct embryo patterning. Multiple overlapping transcriptional units exist at the Hoxa5 locus reflecting the complexity of Hox clustering: a major form of 1.8 kb corresponding to the two characterized exons of the gene and polyadenylated RNA species of 5.0, 9.5 and 11.0 kb. This transcriptional intricacy raises the question of the involvement of the larger transcripts in Hox function and regulation.

Methodology/principal Findings: We have undertaken the molecular characterization of the Hoxa5 larger transcripts. They initiate from two highly conserved distal promoters, one corresponding to the putative Hoxa6 promoter, and a second located nearby Hoxa7. Alternative splicing is also involved in the generation of the different transcripts. No functional polyadenylation sequence was found at the Hoxa6 locus and all larger transcripts use the polyadenylation site of the Hoxa5 gene. Some larger transcripts are potential Hoxa6/Hoxa5 bicistronic units. However, even though all transcripts could produce the genuine 270 a.a. HOXA5 protein, only the 1.8 kb form is translated into the protein, indicative of its essential role in Hoxa5 gene function. The Hoxa6 mutation disrupts the larger transcripts without major phenotypic impact on axial specification in their expression domain. However, Hoxa5-like skeletal anomalies are observed in Hoxa6 mutants and these defects can be explained by the loss of expression of the 1.8 kb transcript. Our data raise the possibility that the larger transcripts may be involved in Hoxa5 gene regulation.

Significance: Our observation that the Hoxa5 larger transcripts possess a developmentally-regulated expression combined to the increasing sum of data on the role of long noncoding RNAs in transcriptional regulation suggest that the Hoxa5 larger transcripts may participate in the control of Hox gene expression.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010600PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2868907PMC
May 2010

Comparative analysis of Hoxa5 allelic series.

Genesis 2007 Apr;45(4):218-28

Centre de Recherche en Cancérologie de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, Canada.

Analysis of the Hoxa5(-/-) mutants has revealed the critical role of Hoxa5 in survival, specification of axial identity, and ontogeny of organs, including the respiratory tract. The presence of the selection cassette in the original Hoxa5(-/-) mutation may interfere with the interpretation of the phenotypes. To circumvent this aspect and to bypass the lethality of the Hoxa5 mutation, we have designed a conditional approach and generated Hoxa5 allelic variants. The conditional allele (Hoxa5(floxed)) behaves as a wild-type allele. In contrast, both the Hoxa5(Delta) and the Hoxa5(floxneo) alleles are characterized by the loss of the functional transcript and protein, the lethality due to lung defects and the skeletal homeotic transformations similar to those of the Hoxa5(-/-) mutants. Analysis of neighboring Hox gene expression patterns in the Hoxa5 mutants produced further confirmed that the Hoxa5 allelic variants are true null alleles.
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http://dx.doi.org/10.1002/dvg.20292DOI Listing
April 2007

Cdx protein interaction with Hoxa5 regulatory sequences contributes to Hoxa5 regional expression along the axial skeleton.

Mol Cell Biol 2005 Feb;25(4):1389-401

Centre de Recherche de L'Hôtel-Dieu de Québec, 9 rue McMahon, Québec, QC G1R 2J6, Canada.

Hox gene functions are intimately linked to correct developmental expression of the genes. The identification of cis-acting regulatory sequences and their associated trans-acting factors constitutes a key step in deciphering the mechanisms underlying the correct positioning of the functional domain of Hox genes along the anterior-posterior axis. We have identified DNA elements driving Hoxa5 regionalized expression in mice, using the 2.1-kb mesodermal enhancer (MES) localized in Hoxa5 3' flanking sequences as a starting point. The MES sequence comprises regulatory elements targeting Hoxa5 expression in the limbs, the urogenital and gastrointestinal tracts, and the cervical-upper thoracic region of the prevertebral column. A 164-bp DNA fragment within the MES caudally restricts Hoxa5 expression at the level of prevertebra 10, corresponding to the posterior limit of its functional domain. Cdx proteins directly bind to this element in vitro via two conserved sites. Preventing Cdx binding by mutating the sites causes caudal expansion of the transgene expression domain. Of all three murine Cdx proteins that bind this element in vitro, Cdx4 has emerged as a potential regional posterior repressor of Hoxa5 expression. The restrictive control provided by Cdx interactions with Hoxa5 regulatory sequences may be one of the critical events in cervicothoracic axial specification.
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http://dx.doi.org/10.1128/MCB.25.4.1389-1401.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC548006PMC
February 2005