SN2 DNA-alkylating agent-induced phosphorylation of p53 and activation of p21 gene expression

Aruna S. Jaiswal, Satya Narayan

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


p53 is an important player in the cellular response to genotoxic stress whose functions are regulated by phosphorylation of a number of serine and threonine residues. Phosphorylation of p53 influences its DNA-binding and gene regulation activities. This study examines p53 phosphorylation in HCT-116 (MMR-deficient) and HCT-116+ch3 (MMR-proficient) human colon cancer cells treated with a SN2 DNA-alkylating agent, methylmethane sulfonate (MMS). MMS induces phosphorylation of p53 on Ser15 and Ser392 in a dose- and time-dependent manner. MMS-induced p53 phosphorylation is independent of DNA mismatch repair (MMR) activity. Nuclear extracts from MMS-treated HCT-116 cells had higher p21WAF1/Cip1 (p21) promoter DNA-binding activity in vitro opposed to untreated cells. After MMS treatment, the activation of the cloned p21 promoter in a transient transfection assay and endogenous p21 mRNA levels in HCT-116(p53+/+) versus HCT-116(p53-/-) cells increased, which correlates with an increased levels of phospho-p53(Ser15) and phospho-p53(Ser392). These results suggest that SN2 DNA-alkylating agent-induced phosphorylation of p53 on Ser15 and Ser392 increases its DNA-binding properties to cause an increased expression of p21 that may play a role in cell cycle arrest and/or apoptosis of HCT-116 cells.

Original languageEnglish (US)
Pages (from-to)17-30
Number of pages14
JournalMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Issue number1-2
StatePublished - Mar 20 2002
Externally publishedYes


  • DNA alkylation
  • DNA-binding
  • p21 Gene regulation
  • p53 Phosphorylation

ASJC Scopus subject areas

  • Genetics
  • Molecular Biology
  • Health, Toxicology and Mutagenesis


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