STYK1 is a putative serine-threonine and tyrosine receptor protein kinase belonging to the fibroblast growth factor receptor (FGFR) family. Overexpression of STYK1 transforms normal cells into malignant tumors in nude mice. Inactivation of a tyrosine residue in the catalytic STYK1 domain attenuates the tumorigenic potential of BaF3-E/N tumor cells in vivo. Collectively, these data strongly implicate an oncogenic role for STYK1 in cancer although the mechanism for STYK1 regulation remains to be established. We have recently shown that estradiol induces STYK1 expression in breast cancer cells. To date, the role of STYK1 expression in ovarian cancer has not been determined. To investigate this issue, a panel of 36 ovarian cancer tissues and 12 cases of normal and benign ovarian tumor tissues were evaluated for STYK1 expression by immunohistochemistry. STYK1 reactivity in the epithelium and stroma of the ovarian tissue was semi-quantitatively scored from 0 to 3. All ovarian cancer tissues were positive for STYK1. On the contrary, all tissues negative for STYK1 expression were either normal or benign. Identifying the molecular mechanisms that regulate STYK1 expression in ovarian cancer is crucial to the development of more effective anti-cancer treatments. We studied six ovarian cancer cell lines of different metastatic potential and one benign ovarian cell line to explore STYK1 expression. Each of the cell lines expressed STYK1 as determined by RT-PCR. To determine if estrogen regulates STYK1 expression in ovarian cancer cells, we treated the cells with 5 x 10-8 M estradiol for 4 hours. qRT-PCR was utilized to elucidate differential STYK1 expression levels. We detected both increased and decreased expression of STYK1 in the estradiol-treated cells compared to the untreated controls. STYK1 protein levels were also up- and downregulated in estrogen-treated cells as determined by Western blot analysis. We conclude that STYK1 is a putative oncogene and is regulated by estrogen in ovarian carcinoma cell lines. STYK1 might also serve as a putative prognostic marker for malignant ovarian tissues.

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 528.

100th AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO