Effects Of ST7L Gene On Cell Growth, Migration And Invasion Of Ovarian Cancer Cells

Objective: Ovarian cancer is one of the common malignant tumors of female genital organs in the world. Its incidence and mortality is the third in female genital malignant tumors preceded only by cervical cancers and uterine cancers, and the mortality of ovarian epithelial cancer is the first of all gynecologic cancers, which affects the health and lives of women. Therefore, it is of great significance to investigate the occurrence and development of ovarian epithelial cancer. It has been reported that the development of ovarian epithelial cancer is associated with the abnormal expressions of oncogenes and the tumor suppressor genes, and the inactivation of the tumor suppressor genes may promote the formation of tumor cells and the malignancy. ST7 L, a homolog of tumor suppressor gene ST7, is located on chromosome 7q31 region. Chen et al. reported that ST7 L could inhibit cell proliferation and invasion, as well as induce apoptosis in glioma cells. While its functions and molecular mechanisms in ovarian cancer have not been fully elucidated yet. This study aims to investigate the effects of ST7 L on cell growth, migration and invasion in ovarian cancer cell lines OVCAR3 and SKOV3, as well as to elucidate its molecular mechanisms.Method:We first constructed the overexpression vector pcDNA3/ST7 L by PCR amplification and the knocking-down vector pSilencer/ST7 L by annealing the synthesized oligos. After performing qRT-PCR and western blot analyses to confirm their efficiencies, we performed the further functional studies using these constructions. To investigate the effects of ST7 L on cell proliferation, migration, invasion, cell cycle as well as apoptosis, we performed MTT assays, colony formation assays, transwell migration, invasion assays and flow cytometry analysis. Meanwhile, we performed western blot analysis to evaluate the effects of ST7 L on epithelial mesenchymal transition by determining the EMT biomarkers and further to elucidate its moecular mechanisms.Result:We found that the expression of ST7 L was decreased in ovarian cancer tissues compared with the adjacent normal tissues by qRT-PCR. Functionally, overexpression of ST7 L could inhibit the cell viability and cell proliferation, as determined by MTT assays and colony formation assays, respectively. Further, overexpression of ST7 L could inhibit cell migration and invasion, as evaluated by transwell migration/invasion assays. Similarly, the cell cycle arrest was also observed by overexpressing ST7 L in ovarian cancer cells. By performing western blot analyses to determine the expressions of epithelial biomarkers and mesenchymal biomarkers, we found that ST7 L could inhibit the epithelial to mesenchymal transition.Conclusion: ST7 L can inhibit the viability and proliferation in ovarian cancer cells, which was due to the induction of cell apoptosis and cell cycle arrest. Further, ST7 L can decrease the migration and invasion abilities by inhibiting the epithelial to mesenchymal transition. Taken together, ST7 L plays a tumor suppressor role in ovarian cancer cells. The detailed molecular mechanisms and its related signal pathways need to be further elucidated.