Etude des altérations de la polarité et de l’adhésion cellulaire dans les cancers du sein

Apicobasal polarity is maintained by the combined action of several protein complexes – PAR, SCRIBBLE and CRUMBS – together with the structural organisation of adherent and tight junctions. Apicobasal polarity is important for the regulation of cell division, apoptosis and cell migration, and several studies show that disruption of cell polarity is involved in tumour progression. Our work focused on the biological mechanisms responsible for the altered apicobasal polarity and cell adhesion observed in breast cancers. To do so, we studied two types of breast carcinomas – invasive lobular carcinoma (ILC) and invasive micropapillary carcinoma (IMPC) – whose morphology suggests specific alterations of these cell processes. Our approach combined genomic, transcriptomic and phenotypical comparative analyses, using a group of invasive carcinomas not special type (IC-NST) as control.Lobular carcinomas are generally characterized by alterations of the E cadherin/ catenin complex and their ability to disseminate. We have shown that they also present a downregulation of PAR-3, a protein of the PAR complex, associated with deregulation of genes involved in cell adhesion (ADAM12, LOXL2), cell-extracellular matrix interactions (MMP11, COL11A1, etc…) and invasion (ACTR2, PAK1). Quantitative defects in components of the extracellular matrix were also observed. We have thus been able to establish a transcriptomic signature for this tumour entity, in agreement with the phenotypical observations.Micropapillary carcinomas show an abnormal polarity characterized by the absence of apical markers or their localization at the inverted apical pole, the loss of Golgi protein GM130 correct orientation and abnormal expression or localization of occludin (tight junctions), CDC42 and aPKC(PAR complex proteins). At the genomic level, we have identified somatic mutations in genes involved in polarity (DNAH9, FOXO3) and ciliogenesis regulation (BBS9, BBS12, SEC63), cytoskeleton organisation (HSP90B1, UBR4, ZFYVE26) and motility (FMN2). At the transcriptomic level, we observed deregulation of genes involved in cell-cell, cell-extracellular matrix adhesion and angiogenesis. IMPC also demonstrate the specific overexpression of a protein of the CRUMBS complex, LIN7A. We established an in vitro model and showed that LIN7A is an efficiently modifier of MCF10A’s polarity. Its overexpression in MCF10A cells cultured in 3-D conditions induces the formation of proliferating multi-lobar acini with no central lumen. This absence of a central lumen is due to an inhibition of apoptosis. MCF10A-LIN7A cells also show an increased ability to grow in suspension, indicating resistance to anoikis. This resistance seems to be linked to a decrease of p38protein’s phosphorylation.This detailed description of biological alterations in special types of breast carcinomas will contribute to more specific treatments provided to the patients, through the identification of new therapeutic targets or therapeutic strategies.La polarité apico-basale des cellules épithéliales est maintenue au niveau cellulaire par l’implication de plusieurs complexes protéiques, PAR, SCRIBBLE et CRUMBS, et par l’intégrité des jonctions serrées et adhérentes. La polarité apico-basale est essentielle au bon déroulement des processus de division, d’apoptose et de migration cellulaire, et de nombreuses études montrent que les perturbations de la polarité interviennent dans la progression tumorale. Notre travail a porté sur la recherche d’anomalies biologiques modifiant la polarité apico basale et l’adhésion cellulaire dans les carcinomes mammaires. Nous avons choisi d’étudier deux types spéciaux de carcinomes mammaires infiltrant, dont le phénotype suggère l’existence d’altérations spécifiques de ces processus biologiques: le type lobulaire (ILC) et le type micropapillaire (IMPC). Ces études ont été menées par des analyses combinées phénotypiques, transcriptomiques et génomiques comparatives, par rapport à un groupe de carcinomes mammaires sans autre spécificité (IC-NST).Les carcinomes lobulaires sont caractérisés par les altérations du complexe E cadhérine/ caténine et leur capacité de dissémination métastatique. Nous avons montré qu’ils présentent également une sous-expression de la protéine du complexe PAR, PAR-3, associée à des altérations des gènes impliqués dans l’adhésion cellulaire (ADAM12, LOXL2), l’interaction cellule-matrice extracellulaire (MMP11, COL11A1, etc…) et l’invasion (ACTR2, PAK1). Des défauts quantitatifs des constituants de la matrice extracellulaire ont également été mis en évidence. Nous avons, ainsi, pu établir une signature transcriptomique spécifique de cette entité tumorale, en accord avec les caractéristiques morphologiques observées. Les carcinomes micropapillaires présentent une polarité anormale caractérisée par des marqueurs apicaux positionnés vers la matrice extracellulaire ou absents, la perte de l’orientation de la protéine golgienne GM130, des anomalies des jonctions serrées (occludine) et des protéines du complexe PAR (CDC42 et aPKC). Au niveau génomique, nous avons mis en évidence des mutations somatiques de gènes impliqués dans la régulation de la polarité (DNAH9, FOXO3) et de la ciliogenèse (BBS9, BBS12, SEC63), l’organisation du cytosquelette (HSP90B1, UBR4, ZFYVE26) et la motilité (FMN2). Au niveau transcriptomique, une nette perturbation des gènes impliqués dans l’adhésion cellule cellule, cellule-matrice extracellulaire et l’angiogenèse est observée. Les IMPC présentent également une surexpression spécifique d’une protéine du complexe CRUMBS, LIN7A. Nous avons établi un modèle in vitro et avons montré que LIN7A est un puissant perturbateur de la polarité apico basale. Sa surexpression dans la lignée MCF10A cultivée en 3D induit la formation d’acini multilobés, à forte capacité proliférative et sans lumière centrale. Cette absence de lumière centrale est due à une inhibition de l’apoptose. Les cellules MCF10A-LIN7A présentent également une capacité accrue de croissance en suspension, témoignant d’une résistance à l’anoïkis. Cette résistance est due, entre autre, à une diminution de la phosphorylation de la protéine p38. Cette description approfondie des altérations biologiques de types spéciaux de carcinomes mammaires doit permettre à moyen terme de proposer une prise en charge plus spécifique des patientes, grâce à l’identification de nouvelles possibilités thérapeutiques ou à une stratégie de désescalade thérapeutique

JUN Oncogene Amplification and Overexpression Block Adipocytic Differentiation in Highly Aggressive Sarcomas

SummaryThe human oncogene JUN encodes a component of the AP-1 complex and is consequently involved in a wide range of pivotal cellular processes, including cell proliferation, transformation, and apoptosis. Nevertheless, despite extensive analyses of its functions, it has never been directly involved in a human cancer. We demonstrate here that it is highly amplified and overexpressed in undifferentiated and aggressive human sarcomas, which are blocked at an early step of adipocyte differentiation. We confirm by cellular and xenograft mouse models recapitulating these sarcoma genetics that the failure to differentiate is dependent upon JUN amplification/overexpression

Mild dyslipidemia accelerates tumorigenesis through expansion of Ly6Chi monocytes and differentiation to pro-angiogenic myeloid cells

Cancer and cardiovascular disease (CVD) share common risk factors such as dyslipidemia, obesity and inflammation. However, the role of pro-atherogenic environment and its associated low-grade inflammation in tumor progression remains underexplored. Here we show that feeding C57BL/6J mice with a non-obesogenic high fat high cholesterol diet (HFHCD) for two weeks to induce mild dyslipidemia, increases the pool of circulating Ly6Chi monocytes available for initial melanoma development, in an IL-1β-dependent manner. Descendants of circulating myeloid cells, which accumulate in the tumor microenvironment of mice under HFHCD, heighten pro-angiogenic and immunosuppressive activities locally. Limiting myeloid cell accumulation or targeting VEGF-A production by myeloid cells decrease HFHCD-induced tumor growth acceleration. Reverting the HFHCD to a chow diet at the time of tumor implantation protects against tumor growth. Together, these data shed light on cross-disease communication between cardiovascular pathologies and cancer

Reversible transitions between noradrenergic and mesenchymal tumor identities define cell plasticity in neuroblastoma

Noradrenergic and mesenchymal identities have been characterized in neuroblastoma cell lines according to their epigenetic landscapes and core regulatory circuitries. However, their relationship and relative contribution in patient tumors remain poorly defined. We now document spontaneous and reversible plasticity between the two identities, associated with epigenetic reprogramming, in several neuroblastoma models. Interestingly, xenografts with cells from each identity eventually harbor a noradrenergic phenotype suggesting that the microenvironment provides a powerful pressure towards this phenotype. Accordingly, such a noradrenergic cell identity is systematically observed in single-cell RNA-seq of 18 tumor biopsies and 15 PDX models. Yet, a subpopulation of these noradrenergic tumor cells presents with mesenchymal features that are shared with plasticity models, indicating that the plasticity described in these models has relevance in neuroblastoma patients. This work therefore emphasizes that intrinsic plasticity properties of neuroblastoma cells are dependent upon external cues of the environment to drive cell identity

8p22 MTUS1 Gene Product ATIP3 Is a Novel Anti-Mitotic Protein Underexpressed in Invasive Breast Carcinoma of Poor Prognosis

BACKGROUND: Breast cancer is a heterogeneous disease that is not totally eradicated by current therapies. The classification of breast tumors into distinct molecular subtypes by gene profiling and immunodetection of surrogate markers has proven useful for tumor prognosis and prediction of effective targeted treatments. The challenge now is to identify molecular biomarkers that may be of functional relevance for personalized therapy of breast tumors with poor outcome that do not respond to available treatments. The Mitochondrial Tumor Suppressor (MTUS1) gene is an interesting candidate whose expression is reduced in colon, pancreas, ovary and oral cancers. The present study investigates the expression and functional effects of MTUS1 gene products in breast cancer. METHODS AND FINDINGS: By means of gene array analysis, real-time RT-PCR and immunohistochemistry, we show here that MTUS1/ATIP3 is significantly down-regulated in a series of 151 infiltrating breast cancer carcinomas as compared to normal breast tissue. Low levels of ATIP3 correlate with high grade of the tumor and the occurrence of distant metastasis. ATIP3 levels are also significantly reduced in triple negative (ER- PR- HER2-) breast carcinomas, a subgroup of highly proliferative tumors with poor outcome and no available targeted therapy. Functional studies indicate that silencing ATIP3 expression by siRNA increases breast cancer cell proliferation. Conversely, restoring endogenous levels of ATIP3 expression leads to reduced cancer cell proliferation, clonogenicity, anchorage-independent growth, and reduces the incidence and size of xenografts grown in vivo. We provide evidence that ATIP3 associates with the microtubule cytoskeleton and localizes at the centrosomes, mitotic spindle and intercellular bridge during cell division. Accordingly, live cell imaging indicates that ATIP3 expression alters the progression of cell division by promoting prolonged metaphase, thereby leading to a reduced number of cells ungergoing active mitosis. CONCLUSIONS: Our results identify for the first time ATIP3 as a novel microtubule-associated protein whose expression is significantly reduced in highly proliferative breast carcinomas of poor clinical outcome. ATIP3 re-expression limits tumor cell proliferation in vitro and in vivo, suggesting that this protein may represent a novel useful biomarker and an interesting candidate for future targeted therapies of aggressive breast cancer

Polarity and cellular adhesion abnormalities in breast carcinomas

La polarité apico-basale des cellules épithéliales est maintenue au niveau cellulaire par l’implication de plusieurs complexes protéiques, PAR, SCRIBBLE et CRUMBS, et par l’intégrité des jonctions serrées et adhérentes. La polarité apico-basale est essentielle au bon déroulement des processus de division, d’apoptose et de migration cellulaire, et de nombreuses études montrent que les perturbations de la polarité interviennent dans la progression tumorale. Notre travail a porté sur la recherche d’anomalies biologiques modifiant la polarité apico basale et l’adhésion cellulaire dans les carcinomes mammaires. Nous avons choisi d’étudier deux types spéciaux de carcinomes mammaires infiltrant, dont le phénotype suggère l’existence d’altérations spécifiques de ces processus biologiques: le type lobulaire (ILC) et le type micropapillaire (IMPC). Ces études ont été menées par des analyses combinées phénotypiques, transcriptomiques et génomiques comparatives, par rapport à un groupe de carcinomes mammaires sans autre spécificité (IC-NST).Les carcinomes lobulaires sont caractérisés par les altérations du complexe E cadhérine/ caténine et leur capacité de dissémination métastatique. Nous avons montré qu’ils présentent également une sous-expression de la protéine du complexe PAR, PAR-3, associée à des altérations des gènes impliqués dans l’adhésion cellulaire (ADAM12, LOXL2), l’interaction cellule-matrice extracellulaire (MMP11, COL11A1, etc…) et l’invasion (ACTR2, PAK1). Des défauts quantitatifs des constituants de la matrice extracellulaire ont également été mis en évidence. Nous avons, ainsi, pu établir une signature transcriptomique spécifique de cette entité tumorale, en accord avec les caractéristiques morphologiques observées. Les carcinomes micropapillaires présentent une polarité anormale caractérisée par des marqueurs apicaux positionnés vers la matrice extracellulaire ou absents, la perte de l’orientation de la protéine golgienne GM130, des anomalies des jonctions serrées (occludine) et des protéines du complexe PAR (CDC42 et aPKC). Au niveau génomique, nous avons mis en évidence des mutations somatiques de gènes impliqués dans la régulation de la polarité (DNAH9, FOXO3) et de la ciliogenèse (BBS9, BBS12, SEC63), l’organisation du cytosquelette (HSP90B1, UBR4, ZFYVE26) et la motilité (FMN2). Au niveau transcriptomique, une nette perturbation des gènes impliqués dans l’adhésion cellule cellule, cellule-matrice extracellulaire et l’angiogenèse est observée. Les IMPC présentent également une surexpression spécifique d’une protéine du complexe CRUMBS, LIN7A. Nous avons établi un modèle in vitro et avons montré que LIN7A est un puissant perturbateur de la polarité apico basale. Sa surexpression dans la lignée MCF10A cultivée en 3D induit la formation d’acini multilobés, à forte capacité proliférative et sans lumière centrale. Cette absence de lumière centrale est due à une inhibition de l’apoptose. Les cellules MCF10A-LIN7A présentent également une capacité accrue de croissance en suspension, témoignant d’une résistance à l’anoïkis. Cette résistance est due, entre autre, à une diminution de la phosphorylation de la protéine p38. Cette description approfondie des altérations biologiques de types spéciaux de carcinomes mammaires doit permettre à moyen terme de proposer une prise en charge plus spécifique des patientes, grâce à l’identification de nouvelles possibilités thérapeutiques ou à une stratégie de désescalade thérapeutique.Apicobasal polarity is maintained by the combined action of several protein complexes – PAR, SCRIBBLE and CRUMBS – together with the structural organisation of adherent and tight junctions. Apicobasal polarity is important for the regulation of cell division, apoptosis and cell migration, and several studies show that disruption of cell polarity is involved in tumour progression. Our work focused on the biological mechanisms responsible for the altered apicobasal polarity and cell adhesion observed in breast cancers. To do so, we studied two types of breast carcinomas – invasive lobular carcinoma (ILC) and invasive micropapillary carcinoma (IMPC) – whose morphology suggests specific alterations of these cell processes. Our approach combined genomic, transcriptomic and phenotypical comparative analyses, using a group of invasive carcinomas not special type (IC-NST) as control.Lobular carcinomas are generally characterized by alterations of the E cadherin/ catenin complex and their ability to disseminate. We have shown that they also present a downregulation of PAR-3, a protein of the PAR complex, associated with deregulation of genes involved in cell adhesion (ADAM12, LOXL2), cell-extracellular matrix interactions (MMP11, COL11A1, etc…) and invasion (ACTR2, PAK1). Quantitative defects in components of the extracellular matrix were also observed. We have thus been able to establish a transcriptomic signature for this tumour entity, in agreement with the phenotypical observations.Micropapillary carcinomas show an abnormal polarity characterized by the absence of apical markers or their localization at the inverted apical pole, the loss of Golgi protein GM130 correct orientation and abnormal expression or localization of occludin (tight junctions), CDC42 and aPKC(PAR complex proteins). At the genomic level, we have identified somatic mutations in genes involved in polarity (DNAH9, FOXO3) and ciliogenesis regulation (BBS9, BBS12, SEC63), cytoskeleton organisation (HSP90B1, UBR4, ZFYVE26) and motility (FMN2). At the transcriptomic level, we observed deregulation of genes involved in cell-cell, cell-extracellular matrix adhesion and angiogenesis. IMPC also demonstrate the specific overexpression of a protein of the CRUMBS complex, LIN7A. We established an in vitro model and showed that LIN7A is an efficiently modifier of MCF10A’s polarity. Its overexpression in MCF10A cells cultured in 3-D conditions induces the formation of proliferating multi-lobar acini with no central lumen. This absence of a central lumen is due to an inhibition of apoptosis. MCF10A-LIN7A cells also show an increased ability to grow in suspension, indicating resistance to anoikis. This resistance seems to be linked to a decrease of p38protein’s phosphorylation.This detailed description of biological alterations in special types of breast carcinomas will contribute to more specific treatments provided to the patients, through the identification of new therapeutic targets or therapeutic strategies

PPAPDC1B and WHSC1L1 Are Common Drivers of the 8p11-12 Amplicon, Not Only in Breast Tumors But Also in Pancreatic Adenocarcinomas and Lung Tumors

International audienceAmplification of the 8p11-12 chromosomal region is a common genetic event in many epithelial cancers. In breast cancer, several genes within this region have been shown to display oncogenic activity. Among these genes, the enzyme-encoding genes, PPAPDC1B and WHSC1L1, have been identified as potential therapeutic targets. We investigated whether PPAPDC1B and WHSC1L1 acted as general driver genes, thereby serving as therapeutic targets in other tumors with 8p11-12 amplification. By using publicly available genomic data from a panel of 883 cell lines derived from different cancers, we identified the cell lines presenting amplification of both WHSC1L1 and PPAPDC1B. In particular, we focused on cell lines derived from lung cancer and pancreatic adenocarcinoma and found a correlation between the amplification of PPAPDC1B and WHSC1L1 with their overexpression. Loss-of-function studies based on the use of siRNA and shRNA demonstrated that PPAPDC1B and WHSC1L1 played a major role in regulating the survival of pancreatic adenocarcinoma and small-cell lung cancer-derived cell lines, both in anchorage-dependent and anchorage-independent conditions, displaying amplification and overexpression of these genes. We also demonstrated that PPAPDC1B and WHSC1L1 regulated xenograft growth in these cell lines. Finally, quantitative RT-PCR experiments after PPAPDC1B and WHSC1L1 knockdown revealed exclusive PPAPDC1B and WHSC1L1 gene targets in small-cell lung cancer and pancreatic adenocarcinoma-derived cell lines compared with breast cancer