The Regulation Role And Mechanism Of Octamer-Binding Transcription Factor 1 On Migration And Invasion In Ovarian Cancer

Background and significanceOCT1(Octamer binding transcription factor 1)is involved in the regulation of a variety of physiological and pathological processes as a transcription factor.Studies have demonstrated that OCT1 regulated progression of several cancers,such as gastric and colorectal cancer,and was closely relevant to poorer prognosis of patients.OCT1 has been reported to promote proliferation,migration and invasion of cancer cells through regulating ERK and other signaling pathways in cancers.However,the roles and mechanisms of OCT1 in ovarian cancer have not been studied or reported yet.Therefore,studying OCT1 in ovarian cancer might help define a new therapeutic target for the treatment of ovarian cancer,and provide experimental and theoretical basis for the targeted therapy of ovarian cancer.MethodsTo assess the correlation between OCT1 protein expression and ovarian cancer,the expression of OCT1 in clinical ovarian cancer specimens and in different ovarian cancer cell lines was detected by immunohistochemistry(IHC)and Western blot respectively.Ovarian cancer cells were silenced/knockdowned and overexpressed by reverse transfection of siRNAs and lentivirus infection,respectively,and their effects were confirmed by real-time quantitative PCR(qRT-PCR)and Western blot.The effects of OCT1 on proliferation,migration and invasion of ovarian cancers were investigated by MTT assays and transwell migration and invasion assays.The expression of related proteins was detected by western blot.The mouse lung metastasis of ovarian cancer model was used to verify the effects of shRNA-OCT1 on metastasis in vivo.ResultsIHC staining showed that OCT1 was highly expressed in epithelial ovarian cancer specimens,especially in clear cell and serous ovarian cancer.Western blots of OCT1 protein levels in non-tumor normal human ovarian epithelial cell line HOSEpiC and ovarian cancer epithelial cell lines A2780,SKOV3,and HO8910 showed that OCT1 was highly expressed in SKOV3 and HO8910 cell lines.Therefore,these two cell lines were studied further in later experiments.These results all suggested that there might be a correlation between OCT1 and ovarian cancers.Silencing OCT1 with siRNAs significantly inhibited migration and invasion of ovarian cancers,and silencing OCT1 induced up-regulation of ZO-1 and down-regulation of Fibronectin and ERK proteins through Western blots.Overexpression of OCT1 by lentivirus promoted migration and invasion of ovarian cancers and caused down-regulation of ZO-1 and up-regulation of Fibronectin.These results demonstrated that OCT1 can regulate the migration and invasion of ovarian cancer in vitro and participate in the regulation of EMT,migration,and invasion related pathways.In addition,shRNA-OCT1 was shown to inhibite migration and invasion of ovarian cancer cell lines and the ability of metastasis of ovarian cancer cells in mouse lung metastasis model.The above results have demonstrated that knockdown of OCT1 gene successfully inhibited the metastasis of ovarian cancer cells to lungs in mice.ConclusionThis study showed that OCT1 is highly correlated with ovarian cancer,not only involved in regulating migration and invasion of ovarian cancer,but also involved in the regulation of multiple EMT,migration,and invasion related signaling pathways.In summary,these results can help to understand the roles and mechanisms of OCT1 in ovarian cancer and OCT1 is a potential new target for the treatment of ovarian cancer.In addition,these results provide experimental data and theoretical basis for identification of novel biomarkers for diagnosis and treatment of ovarian cancer and development of novel targeted drugs.