αvβ6 integrin-A marker for the malignant potential of epithelial ovarian cancer

The mechanism(s) responsible for the progression of non-metastatic or borderline ovarian cancer to invasive Grade I/III ovarian cancer is still unknown. An epithelium-restricted integrin, α_vβ₆, is present in malignant epithelia but not in normal epithelia. We studied the relative expression and distribution of α_vβ₆ integrin in early and late-stage invasive (Grade I and Grade III) and non-invasive (benign and borderline) ovarian tumors of serous, mucinous, endometrioid, and clear-cell carcinoma subtypes, to assess its potential as a marker for epithelial ovarian cancer progression. Sixty-six specimens, including eight normal, 13 benign, 14 borderline, 13 Grade I, and 18 Grade III tumors were evaluated by immunohistochemistry (IHC) using a monoclonal antibody (MAb) against α_vβ₆ integrin. Normal ovarian surface epithelium was negative for α_vβ₆ integrin expression. All 45 carcinomas studied were positive, and the staining intensity significantly correlated with the grade of the tumor. The Grade III carcinomas of all types showed strong staining intensity. Only mucinous benign tissues were positive, and no reactivity was observed in benign serous neoplasms. On the basis of these observations, we hypothesize that the expression of α_vβ₆ integrin is associated with epithelial ovarian cancer and that a gradual increase in the expression of the molecule may be a correlative index of the progression of this disease.