Overexpression of the osteopontin correlates with the aggressiveness of endometrial cancer

Abstract

5038 Background: To test the hypothesis that expression of osteopontin (OPN), an integrin-binding glycoprotein, can independently predict the potential aggressiveness of endometrial cancer. We studied OPN expression in endometrial cell carcinomas and correlated OPN expression levels with clinicopathologic tumor features. Methods: The status of OPN expression in benign and malignant endometrial cancer cell lines and tissues was analyzed by Western blot and immunohistochemistry. Nonparametric Spearman’s correlation coefficient method was used to assess the statistical significance of the correlation between clinicopathologic characteristics of tumor and OPN expression. Results: An increased expression of OPN was observed in the endometrial cancer compared to normal endometrial tissue samples. When the level of OPN in normal tissue was set at 1, its level in benign endometrial hyperplasia was slightly increased at 1.2, whereas the OPN level in the highly malignant endometrial carcinoma tissue was greatly increased by nearly 3- 5 folds. Amongst the 70 cases examined immunocytochemically, of the 23 grade 1 endometrial carcinomas, 6 were unstained and 12 stained weakly positive (+). For the 20 grade 3 or serous type endometrial carcinomas analyzed, 8 (40%) stained strongly positive (+++), 8 (40%) stained moderately positive (++) and 1 stained weakly positive (+). These results showed that the level of OPN expressed between grade 1 and grde 3 or more was significantly different (Spearman’s correlation coefficient method, p = 0.001). Kaplan-Meier survival analysis showed that the increased level of OPN expression was significantly associated with reduced survival time of the patients. Conclusions: The results suggest that the increased OPN level may be involved in the malignant transformation of endometrial adenocarcinoma cells and OPN expression level is an important determinant for patient survival. No significant financial relationships to disclose.