Stabilization and reactivation of the p53 tumor suppressor protein in nontumorigenic revertants of HeLa cervical cancer cells

Maria Athanassiou, Yanwen Hu, Lichen Jing, Benoit Houle, Helmut Zarbl, Andrei M Mikheev

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

We demonstrated previously that loss of in vitro transformation and in vivo tumorigenicity in two independent revertant clones of HeLa cells (designated HA and HF) resulted from dominant-acting genetic changes. Analysis of the p53 tumor suppressor gene revealed stabilization and at least partial restoration of wild-type p53 transactivation properties pathways in both revertants of HPV-induced cell transformation. The half-lives of the p53 protein and both of the HA and HF clones were increased 4 fold compared with the parental HeLa cells (16, 17, and 4 min, respectively). The levels of E6 viral protein expression were similar in the three cell lines, whereas the levels of the ubiquitin ligase protein, E6 associated protein (EG-AP), were elevated in the revertants. Western blot analysis of immunoaffinity-purified p53 demonstrated that stabilization of p53 in the revertants was correlated with a reduction in the in vivo formation of complexes involving the E6 oncoprotein and p53. Stabilization of p53 function in the revertants did not result from mutations in either the p53 or E6-AP genes. Despite the observed stabilization and restoration of p53 transactivation function in the revertants, exposure of the revertants to DNA-damaging agents did not result in elevated levels of p21(waf-1) protein and failed to induce growth arrest in the G1 phase of the cell cycle. However, p53-independent induction of p21(waf-1) protein also failed to induce the G1 phase of the cell cycle. Thus, restoration of wild-type p53 transactivation activity in the HA and HF revertants is insufficient to induce G1 arrest and reversion from HPV- induced cell transformation in our model system.

Original languageEnglish (US)
Pages (from-to)729-737
Number of pages9
JournalCell Growth and Differentiation
Volume10
Issue number11
StatePublished - Nov 1 1999

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Stabilization and reactivation of the p53 tumor suppressor protein in nontumorigenic revertants of HeLa cervical cancer cells'. Together they form a unique fingerprint.

Cite this