EXPRESSION PATTERN OF THE MRPS18 FAMILY PROTEINS IN CHORDOMA

Chordomas are rare tumors of the axial skeleton that arise from the notochord; they are observed usually at the base of the skull and rarer along the spine. Chordomas are resistant to conventional chemotherapy, that is why it is important, to find the new diagnostic and/or prognostic markers. We have shown recently, that genes of the mitochondrial ribosomal protein S18 (MRPS18) family are differentially expressed in gliomas. The MRPS18-2 oncoprotein is expressed at higher levels in cancerous cells compared to their normal counterpart. Aim. We wanted to investigate the peculiarities of the expression pattern of the MRPS18 family genes in chordoma to better understand their role in cancerogenesis, using an immunohistochemical analysis on chordoma clinical samples. Methods. 15 specimens of chordoma of the base of the skull and 5 samples of the spine localization were studied retrospectively. The specific antibodies against MRPS18-1, MRPS18-2, MRPS18-3, and RB was used for an immunohistochemical analysis. All cases were stained in parallel with appropriate negative control. Results. We found that MRPS18 family proteins are differentially expressed in chordoma tissues. MRPS18-1 showed the strongest signal in all tumor samples. The lowest level of the signal intensity was recorded for the MRPS18-3 protein. In several samples the RB signal was detected in cytoplasm of tumor cells. Importantly, in these samples the strong staining for MRPS18-2 was observed as well. The fine mechanism of sequestering of RB in cytoplasm of cancer cells should be further elucidated. Conclusion, These preliminary results should lead to a larger work on a role of RB-MRPS18 family proteins interaction for chordoma development.