THY-1 induction is associated with up-regulation of fibronectin and thrombospondin-1 in human ovarian cancer

We recently identified THY-1 as a putative tumor suppressor gene for human ovarian cancer. To understand the carcinogenic role of THY-1, and its downstream effects on cancer cells, a THY-1 inducible system was established in the human ovarian cancer cell line SKOV-3 based on the tetracycline (tet) regulating system. To establish an inducible system for Thy-1 expression, two plasmids, pUHD172-1neo and pTEP4mThy-1, which are neomycin and hygromycin resistant were co-transfected into the ovarian carcinoma cell line, SKOV-3. The inducibility of Thy-1 expression in the SKOV-3 cell line by doxycycline (dox) was determined by northern blot analysis, immunocytochemistry, and flow cytometry. A time course study revealed that Thy-1 expression is induced 3 hours post dox exposure. Expression was reversible such that 12 hours post the removal of dox almost no Thy-1 could be detected. Furthermore, 2 genes, Fibronectin (FN) and Thrombospondin (TSP-1) involved in cellular differentiation and the regulation of tumor angiogenesis, respectively, were found to be up-regulated upon THY-1 induction. In contrast, the gene SPARC was found to be independent of Thy-1 expression. This study supports the hypothesis that THY-1 plays a critical role in regulating downstream genes associated with the regulation of ovarian tumor growth and cellular differentiation.