RESUMEN
Previously, we have identified the Grainyhead transcription factor 2 gene (GRHL2) as notably hypomethylated in high-grade (HG) serous epithelial ovarian tumors, compared with normal ovarian tissues. GRHL2 is known for its functions in normal tissue development and wound healing. In the context of cancer, the role of GRHL2 is still ambiguous as both tumorigenic and tumor suppressive functions have been reported for this gene, although a role of GRHL2 in maintaining the epithelial status of cancer cells has been suggested. In this study, we report that GRHL2 is strongly overexpressed in both low malignant potential (LMP) and HG serous epithelial ovarian tumors, which probably correlates with its hypomethylated status. Suppression of the GRHL2 expression led to a sharp decrease in cell proliferation, migration and invasion and induced G1 cell cycle arrest in epithelial ovarian cancer (EOC) cells displaying either epithelial (A2780s) or mesenchymal (SKOV3) phenotypes. However, no phenotypic alterations were observed in these EOC cell lines following GRHL2 silencing. Gene expression profiling and consecutive canonical pathway and network analyses confirmed these data, as in both these EOC cell lines, GRHL2 ablation was associated with the downregulation of various genes and pathways implicated in cell growth and proliferation, cell cycle control and cellular metabolism. Taken together, our data are indicative for a strong oncogenic potential of the GRHL2 gene in EOC progression and support recent findings on the role of GRHL2 as one of the major phenotypic stability factors (PSFs) that stabilize the highly aggressive/metastatic hybrid epithelial/mesenchymal (E/M) phenotype of cancer cells.
Asunto(s)
Puntos de Control del Ciclo Celular/genética , Movimiento Celular/genética , Proteínas de Unión al ADN/genética , Neoplasias Glandulares y Epiteliales/genética , Neoplasias Glandulares y Epiteliales/patología , Neoplasias Ováricas/genética , Neoplasias Ováricas/patología , Factores de Transcripción/genética , Sistemas CRISPR-Cas/genética , Carcinoma Epitelial de Ovario , Línea Celular Tumoral , Proliferación Celular/genética , Metilación de ADN , Proteínas de Unión al ADN/metabolismo , Femenino , Regulación Neoplásica de la Expresión Génica , Técnicas de Inactivación de Genes , Humanos , Inmunohistoquímica , Invasividad Neoplásica , Análisis de Secuencia por Matrices de Oligonucleótidos , Fenotipo , ARN Interferente Pequeño/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Reproducibilidad de los Resultados , Transducción de Señal/genética , Factores de Transcripción/metabolismoRESUMEN
The molecular basis of epithelial ovarian cancer (EOC) dissemination is still poorly understood. Previously, we identified the mannose receptor LY75 gene as hypomethylated in high-grade (HG) serous EOC tumors, compared to normal ovarian tissues. LY75 represents endocytic receptor expressed on dendritic cells and so far, has been primarily studied for its role in antigen processing and presentation. Here we demonstrate that LY75 is overexpressed in advanced EOC and that LY75 suppression induces mesenchymal-to-epithelial transition (MET) in EOC cell lines with mesenchymal morphology (SKOV3 and TOV112), accompanied by reduction of their migratory and invasive capacity in vitro and enhanced tumor cell colonization and metastatic growth in vivo. LY75 knockdown in SKOV3 cells also resulted in predominant upregulation of functional pathways implicated in cell proliferation and metabolism, while pathways associated with cell signaling and adhesion, complement activation and immune response were mostly suppressed. Moreover, LY75 suppression had an opposite effect on EOC cell lines with epithelial phenotype (A2780s and OV2008), by directing epithelial-to-mesenchymal transition (EMT) associated with reduced capacity for in vivo EOC cell colonization, as similar/identical signaling pathways were reversely regulated, when compared to mesenchymal LY75 knockdown EOC cells.To our knowledge, this is the first report of a gene displaying such pleiotropic effects in sustaining the cellular phenotype of EOC cells and points to novel functions of this receptor in modulating EOC dissemination. Our data also support previous findings regarding the superior capacity of epithelial cancer cells in metastatic colonization of distant sites, compared to cancer cells with mesenchymal-like morphology.
Asunto(s)
Antígenos CD/metabolismo , Biomarcadores de Tumor/metabolismo , Movimiento Celular , Cistadenocarcinoma Seroso/secundario , Lectinas Tipo C/metabolismo , Antígenos de Histocompatibilidad Menor/metabolismo , Neoplasias Ováricas/patología , Neoplasias Peritoneales/secundario , Receptores de Superficie Celular/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Animales , Antígenos CD/genética , Apoptosis , Proliferación Celular , Cistadenocarcinoma Seroso/metabolismo , Transición Epitelial-Mesenquimal , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Lectinas Tipo C/antagonistas & inhibidores , Lectinas Tipo C/genética , Ratones Endogámicos NOD , Ratones SCID , Persona de Mediana Edad , Antígenos de Histocompatibilidad Menor/genética , Clasificación del Tumor , Estadificación de Neoplasias , Neoplasias Ováricas/metabolismo , Neoplasias Peritoneales/metabolismo , Fenotipo , Pronóstico , ARN Interferente Pequeño/genética , Receptores de Superficie Celular/antagonistas & inhibidores , Receptores de Superficie Celular/genética , Transducción de Señal , Tasa de Supervivencia , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Previously, we have identified the branched chain amino-acid transaminase 1 (BCAT1) gene as notably hypomethylated in low-malignant potential (LMP) and high-grade (HG) serous epithelial ovarian tumors, compared to normal ovarian tissues. Here we show that BCAT1 is strongly overexpressed in both LMP and HG serous epithelial ovarian tumors, which probably correlates with its hypomethylated status. Knockdown of the BCAT1 expression in epithelial ovarian cancer (EOC) cells led to sharp decrease of cell proliferation, migration and invasion and inhibited cell cycle progression. BCAT1 silencing was associated with the suppression of numerous genes and pathways known previously to be implicated in ovarian tumorigenesis, and the induction of some tumor suppressor genes (TSGs). Moreover, BCAT1 suppression resulted in downregulation of numerous genes implicated in lipid production and protein synthesis, suggesting its important role in controlling EOC metabolism. Further metabolomic analyses were indicative for significant depletion of most amino acids and different phospho- and sphingolipids following BCAT1 knockdown. Finally, BCAT1 suppression led to significantly prolonged survival time in xenograft model of advanced peritoneal EOC. Taken together, our findings provide new insights about the functional role of BCAT1 in ovarian carcinogenesis and identify this transaminase as a novel EOC biomarker and putative EOC therapeutic target.