pRb2/p130 is delocalized in cytoplasm in diffuse gastric cancer: a preliminary study †

pRb2/p130 phosphorylation occurs at G0/G1 transition, when cells exit from quiescence. This phenomenon leads to E2F4 and E2F5 transcription factors releasing, allowing them to activate their target genes. Hence, pRb2/p130 represents one of the most important cell cycle controller because of transcription factors binding/releasing capability. It was previously shown that the loss of expression, or function, of pRb2/p130 is involved in different neoplasms development, due to related loss of control of E2F4 and E2F5 transcription activity. Here we analyzed gastric cancer tissue samples of diffuse histotype, comparing them with the normal counterpart. Yet, we did not find any change of expression levels. Rather, we found a cytoplasmic localization of pRb2/p130 in cancer tissue samples whereas, in normal counterparts, we found the expected nuclear localization. This occurrence lead to hypothesize an almost completely uncontrolled transcriptional activity of E2F4 and E2F5 in this kind of neoplasm, actually contributing to maintenance of transformed status. Although in limited number of cases, our data support the necessity of further investigations to verify the possibility of using pRb2/p130 as diagnostic marker of diffuse gastric cancer.