B-cell receptor-associated protein 31 promotes migration and invasion in ovarian cancer cells.

B cell receptor associated protein 31 (BAP31) is a member of the B cell receptor that functions as a transporter for numerous types of newly formed proteins from the endoplasmic reticulum to the Golgi apparatus. Previous studies found that that BAP31 serves an important role in the pathogenesis of malignancy but its specific effect on ovarian cancer is not clear. The present study aimed to investigate whether BAP31 affects ovarian cancer and its underlying mechanism. In the present study, ovarian cancer tissue, human ovarian normal epithelial cell line IOSE80 and five ovarian cancer cell lines (A2780, Hey-T30, COC1, SKOV3 and OVCAR3) underwent reverse transcription-quantitative PCR, western blotting, Cell Counting Kit-8, Transwell and co-immunoprecipitation (Co-IP) assay and transcriptome sequencing. Previous studies showed that compared with healthy tissues, the expression level of BAP31 protein was found to be significantly higher in various types of cancer tissues, implying that BAP31 may serve an important role in the pathogenesis of cancer. The present study found that BAP31 expression was upregulated in five ovarian cancer cell lines and ovarian cancer tissue, such that BAP31 knockdown [performed using two short hairpin (sh)RNA plasmids] decreased proliferation, invasion and migration. In addition, BAP31 knockdown was found to downregulate the expression of N-cadherin and upregulate the expression of E-cadherin on transcriptional level by controlling the nuclear aggregation of TWIST1, a transcriptional regulator of N-cadherin and E-cadherin. There was no interaction between BAP31 and E-cadherin or N-cadherin using Co-IP detection, while BAP31, E-cadherin and N-cadherin interacted with TWIST1 protein. E-cadherin and N-cadherin expression levels recovered when TWIST1 was overexpressed in the shBCAP31 cells. These results suggest that BAP31 can regulate the migration and invasion of ovarian cancer cells through the epithelial-mesenchymal transition pathway at the transcriptional level, which may be beneficial for the identification of potentially novel targets for ovarian cancer therapy.