Flotillin 1 is differentially expressed in human epithelial ovarian tumors

Although Flotillin 1 (FLOT1) is highly expressed in various human cancers, its relationship with ovarian cancer (OC) remains unknown. This study determines FLOT1 expression in human ovarian tumors and examines its effect on OC cell proliferation. FLOT1 protein expression was assessed in a tissue microarray by immunohistochemical staining. We found that 81.48% malignant and 50% borderline tumors were FLOT1 protein-positive, whereas benign tumors and normal ovarian tissues were negative. The staining was strongest in serous malignant tumor and transitional cell carcinoma and weakest in mucinous tumor. Differentially expressed FLOT1 in freshly isolated serous tumors was confirmed by Western blot and we then evaluated FLOT1 expression association with OC patients' clinical characteristics. Histological typing established that FLOT1 protein expression was significantly associated with serous tumor (P<0.001), and that silencing FLOT1 by FLOT1-siRNA inhibited OVCAR-3 and SK-OV-3 cell proliferation and arrested the cell cycle at the S phase. FLOT1 inhibition increased cyclin E1 protein expression and over-expression partly rescued the FLOT1-shRNA-suppresed cell proliferation. Thus, we demonstrated that FLOT1 is highly expressed in ovarian cancer and its suppression decreases OC cell proliferation. This clearly suggests FLOT1's important role in ovarian tumor growth and provides a novel target for OC treatment.