Report

Decreased translation of p21waf1 mRNA causes attenuated p53 signaling in some p53 wild-type tumors

Volume 11, Issue 9   May 1, 2012
Pages 1818 - 1826
http://dx.doi.org/10.4161/cc.20208
Keywords: Chk1, MK-8776, UCN-01, cell cycle checkpoints, p21waf1, p53 response
Authors: Li-Ju Chang and Alan Eastman

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Abstract:
DNA damage induces cell cycle arrest through both Chk1 and the p53 tumor suppressor protein, the latter arresting cells through induction of p21waf1 protein. Arrest permits cells to repair the damage and recover. The frequent loss of p53 in tumor cells makes them more dependent on Chk1 for arrest and survival. However, some p53 wild type tumor cell lines, such as HCT116 and U2OS, are also sensitive to inhibition of Chk1 due to attenuated p21waf1 induction upon DNA damage. The purpose of this study is to determine the cause of this attenuated p21waf1 protein induction. We find that neither the induction of p21waf1 mRNA nor protein half-life is sufficient to explain the low p21waf1 protein levels in HCT116 and U2OS cells. The induced mRNA associates with polysomes but little protein is made suggesting these two cell lines have a reduced rate of p21waf1 mRNA translation. This represents a novel mechanism for disruption of the p53-p21waf1 pathway as currently known mechanisms involve either mutation of p53 or reduction of p53 protein levels. As a consequence, this attenuated p21waf1 expression may render some p53 wild type tumors sensitive to a combination of DNA damage plus checkpoint inhibition.

Received: February 17, 2012; Accepted: March 29, 2012; Published Online: May 1, 2012

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