Abstract: Abstract Objective: To study the expression of tumor necrosis factor superfamily-15 (TNFSF15) in human ovarian cancer specimens, and it’s relationship with the clinical staging. Furthermore, we mean to study the effects of TNFSF15 on tumor angiogenesis and growth in vivo. Methods: The expression of TNFSF15 in ovary tissue specimens (12 normal and 94 ovarian cancer) were detected by immunohistochemistry assay. We used recombinant TNFSF15 to treat ID8-bearing C57BL/6 mice via intraperitoneal injection or used TNFSF15-shRNA to knock down its expression in tumor microenvironment, and then the influences on tumor angiogenesis and growth were assessed. Results：Compared to the normal ovary tissues, the expression of TNFSF15 was low or absent in the cancer specimens（P<0.001）and TNFSF15 levels are inversely correlated to the clinical stages of human ovarian cancer（P<0.005）. Using a mouse syngeneic tumor model, we demonstrated that recombinantNFSF15 markedly inhibited the growth of ID8 tumors（P<0.05）; on the other hand, TNFSF15-shRNAadministration could accelerate the growth of ID8 tumors（P<0.05）. Conclusion: TNFSF15 downregulation or absent in ovarian cancer microenvironment is a pre-requisite for tumor neovascularization and tumor growth.

Key words: ovarian cancer, tumor, neovascularization, ID8 cell lines