The effect of chemotherapy treatment on Ribosomal RNA integrity and ribosomal protein composition in ovarian cancer cells

Abstract

Recently we have demonstrated that several chemotherapy agents, of distinct mechanisms, promote highly reproducible ribosomal RNA (rRNA) degradation patterns, a phenomenon we call RNA disruption. These reproducible rRNA degradation bands have been observed in total RNA preparations from several cancer cell lines originating from various tissues. However, the effect of chemotherapeutic agents on ribosomal integrity and composition (including changes in rRNA and protein content) has not been examined. The purpose of the present study was to investigate the effect of docetaxel (DXL) chemotherapy treatment on ribosomal RNA and protein content in the A2780 ovarian carcinoma cell line. This involved isolation of ribosomes from untreated and DXL-treated A2780 cells using a differential centrifugation method. Differences in ribosomal RNA integrity and protein composition due to DXL treatment were determined using capillary gel electrophoresis (for rRNA), and 1D or 2D gel electrophoresis (for ribosomal proteins). Specific ribosomal proteins were detected by western blotting and quantified using densitometry. We report that DXL treatment of A2780 cells results in time-dependent degradation of rRNAs within isolated ribosomes, as well as changes in their relative protein composition. The DXL-induced changes in ribosome protein composition appeared to precede extensive rRNA degradation and were not observed in DXL-resistant A2780 cells.