Increased expression of ribosomal protein S2 in liver tumors, posthepactomized livers, and proliferating hepatocytes in vitro.

The ribosomal protein S2 (RPS2) is encoded by a gene from the highly conserved mammalian repetitive gene family LLRep3. It participates in aminoacyl-transfer RNA binding to ribosome, potentially affecting the fidelity of mRNA translation. These studies were designed to measure the expression of RPS2 during increased cell proliferation. Using Western and Northern blot analyses, we found that the levels of RPS2 protein and its corresponding mRNA were higher in mouse hepatocellular carcinoma, in mouse livers after one-third partial hepatectomy, and in serum-starved cultured hepatocytes following serum treatment. Our study shows that the increased expression of RPS2 correlates with increased cell proliferation. However, whether the altered expression of this protein reflects its involvement in cellular proliferation or represents an associated phenomena is still a key question that needs to be explored.