Loss of motility-related protein 1 (MRP1/CD9) and integrin alpha3 expression in endometrial cancers

MRP1/CD9 and integrin alpha3 have played crucial roles in cell adhesion, motility, and signaling events. The loss of MRP1/CD9 and integrin alpha3 has been involved in tumor growth and metastasis of cancer cells. The aim of the current study was to clarify the clinical significance of MRP1/CD9 and integrin alpha3 in endometrial cancer.

The expression of MRP1/CD9 and integrin alpha3 from the same tissue sample were examined immunohistochemically in 15 patients with normal endometrium and in 56 patients with uterine endometrioid adenocarcinoma. Disease-free survival curves were estimated using the Kaplan-Meier method and analyzed by the log-rank test between the positive and reduced expression statuses of both MRP1/CD9 and integrin alpha3. These expressions and clinicopathologic variables were analyzed univariately and multivariately.

In normal endometrium, MRP/CD9 was expressed at the cell membrane of cell contact sites, and the expression of integrin alpha3 was detected also at the cell membrane of cell contact sites and at borders of stromal tissues. In patients with endometrioid adenocarcinoma, 17 cases showed reduced expression of MRP1/CD9, and 20 cases had reduced expression of integrin alpha3. Fourteen cases indicated a reduced expression of both MRP1/CD9 and integrin alpha3. Each reduced expression of MRP1/CD9 or integrin alpha3 was significantly correlated with histologic grade and metastasis. Multivariate analysis using the Cox regression model disclosed that age at surgery, metastasis, and expression status of MRP1/CD9 were significant prognostic factors for disease-free survival.

These findings suggested that the analysis for the expression statuses of MRP1/CD9 and integrin alpha3 may provide important information on the clinical behavior of endometrial cancer.