c-Ets1 is a promising marker in epithelial ovarian cancer.

c-Ets1 controls the expression of some genes involved in extracellular matrix remodeling. To elucidate the involvement of c-Ets1 in epithelial ovarian carcinogenesis, we investigated the role of the proto-oncogene c-ets1 in the regulation of physiological processes such as cell proliferation, differentiation, and tumor invasion. Using fluorescent immunohistochemistry, we analyzed serial frozen sections for c-Ets1 protein expression in 26 patients with ovarian epithelial carcinoma, 10 patients with benign cystadenoma of the ovary, and 10 premenopausal patients with normal ovaries. We analyzed the relationship between the percentage of c-Ets1 stained cells in a patient and characteristics of the patient including histological classification, clinical stage, histological grade, and clinical outcome. c-Ets1 was not detected in any cases of benign ovarian cystadenoma. Most of the c-Ets1 proteins were found in the cytoplasm and some in the nucleus of epithelial ovarian cancer tissues. Moreover, c-Ets1 was strongly expressed in the head portion of papillary cancer tissues that had invaded the stroma. c-Ets1 expression was significantly associated with clinical stage (p<0.01), histological grade (p<0.01), and clinical outcome (p<0.01). Survival data were available for all patients and univariate Cox regression analysis showed that c-Ets1 expression was significantly associated with a poor prognosis (p<0.05). Our results demonstrate that c-Ets1 expression in epithelial ovarian cancer correlates to the malignant potential of the tumor.