Expression of the ribosomal proteins Rplp0, Rplp1, and Rplp2 in gynecologic tumors.

Previous work from our laboratory has demonstrated that the expression of the ribosomal protein Rplp1 immortalizes primary cells and is involved in transformation. To investigate the role of the P proteins in tumorigenesis, we examined the messenger RNA expression levels of Rplp0, Rplp1, and Rplp2 in a series of 32 patients with gynecologic tumors. The messenger RNA expression level of all 3 P proteins was increased significantly in the tumor tissue, compared with normal tissue. In addition, a total of 140 biopsies of gynecologic cancers (46 endometrioid and 94 ovarian) were investigated. An up-regulation of P protein expression was observed by immunohistochemistry in an average of 27% of the tumors, as compared with normal tissues. Moreover, the level of P protein up-regulation correlated significantly with p53 expression in serous ovarian cancers. This is an important fact because the level of overexpression of the P proteins correlated with the presence of lymph node metastases in serous ovarian cancers. We also observed that endometrial carcinomas that had invaded the myometrium overexpressed P proteins in the invasive front. In addition, we found that the P proteins are up-regulated in a considerable number of patients with the most common types of cancer. Overall, our study shows that P proteins are involved in human cancer and indicates that the expression level of these proteins could be useful as a prognostic marker in specific subtypes of gynecologic tumors.