Over-expression of fibroblast activation protein alpha increases tumor growth in xenografts of ovarian cancer cells.

Fibroblast activation protein alpha (FAPα) is a 95-kDa serine protease of post-prolyl peptidase family on cell surface. FAPα is widely expressed in tumor microenvironment. The wide spread association of FAPα expression with cancer suggests that it has important functions in the disease. However, the nature of FAPα's roles in cancer cell activity is not well-determined. It has been showed that FAPα silencing in SKOV3 cells induces ovarian tumors but significantly reduces tumor growth in a xenograft mouse model. To further determine the role of FAPα in epithelial ovarian cancer cells, SKOV3-FAPα and HO8910-FAPα cell lines, which over-expressed FAPα stably, were constructed and then their biological behaviors were investigated. It was found that FAPα promoted ovarian cancer cell proliferation, drug resistance, invasiveness, and migration in vitro. Immunochemistry assay showed that FAPα significantly facilitated tumor growth in xenograft tumor tissues. These results suggested that FAPα might directly promote tumor growth and invasiveness in ovarian cancer cells.