Mismatch repair and p53 independently affect sensitivity to N-(2- chloroethyl)-N'-cyclohexyl-N-nitrosourea

Gabriele Aquilina, Sabrina Ceccotti, Simone Martinelli, Silvia Soddu, Marco Crescenzi, Pauline Branch, Peter Karran, Margherita Bignami

Research output: Contribution to journalArticle

Abstract

The contributions of defective mismatch repair (MMR) and the p53- response to cell killing by N-(2-chloroethyl)-N'-cyclohexyl-N-nitrosourea (CCNU) were evaluated. MMR defects were previously shown to be associated with CCNU sensitivity (G. Aquilina et al., Cancer Res., 58: 135-141, 1998). Unexpectedly, eight MMR-deficient variants of the A2780 human ovarian carcinoma cell line were 3-fold more resistant to CCNU than the MMR- proficient parental cells. The variants were members of a preexisting subpopulation of drug-resistant A2780 cells. In addition to deficient expression of the MMR protein hMLH1, an essential component of the hMutLα repair complex, the variants exhibited alterations in the expression of other genes that influence drug sensitivity. Although A2780 cells possess a wild- type p53 gene, all of the clones contained a heterozygous G to T tranversion at codon 172. This change resulted in a Val to Phe substitution and was associated with a constitutive production of high levels of p53, which was inactive as a transcriptional activator of bax and p21. The hMLH1/p53 defective variants displayed a less prominent cell cycle arrest and reduced apoptosis after CCNU treatment. In contrast, MMR-defective A2780 variants, which had a similar hMutLα defect but retained a wild-type p53, did exhibit the expected CCNU sensitivity. Expression of a dominant-negative p53val135 increased CCNU resistance of both MMR-proficient and MMR-deficient A2780 cells. Thus, defective MMR and p53 influence CCNU sensitivity in opposite directions. Their effects are independent, and sensitization by defective MMR does not require a functional p53 response.

Original languageEnglish
Pages (from-to)671-680
Number of pages10
JournalClinical Cancer Research
Volume6
Issue number2
Publication statusPublished - Feb 2000

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DNA Mismatch Repair
p53 Genes
Cell Cycle Checkpoints
Codon
Pharmaceutical Preparations
Clone Cells
Apoptosis
Carcinoma
Gene Expression
Cell Line

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Aquilina, G., Ceccotti, S., Martinelli, S., Soddu, S., Crescenzi, M., Branch, P., ... Bignami, M. (2000). Mismatch repair and p53 independently affect sensitivity to N-(2- chloroethyl)-N'-cyclohexyl-N-nitrosourea. Clinical Cancer Research, 6(2), 671-680.

Mismatch repair and p53 independently affect sensitivity to N-(2- chloroethyl)-N'-cyclohexyl-N-nitrosourea. / Aquilina, Gabriele; Ceccotti, Sabrina; Martinelli, Simone; Soddu, Silvia; Crescenzi, Marco; Branch, Pauline; Karran, Peter; Bignami, Margherita.

In: Clinical Cancer Research, Vol. 6, No. 2, 02.2000, p. 671-680.

Research output: Contribution to journalArticle

Aquilina, G, Ceccotti, S, Martinelli, S, Soddu, S, Crescenzi, M, Branch, P, Karran, P & Bignami, M 2000, 'Mismatch repair and p53 independently affect sensitivity to N-(2- chloroethyl)-N'-cyclohexyl-N-nitrosourea', Clinical Cancer Research, vol. 6, no. 2, pp. 671-680.
Aquilina G, Ceccotti S, Martinelli S, Soddu S, Crescenzi M, Branch P et al. Mismatch repair and p53 independently affect sensitivity to N-(2- chloroethyl)-N'-cyclohexyl-N-nitrosourea. Clinical Cancer Research. 2000 Feb;6(2):671-680.
Aquilina, Gabriele ; Ceccotti, Sabrina ; Martinelli, Simone ; Soddu, Silvia ; Crescenzi, Marco ; Branch, Pauline ; Karran, Peter ; Bignami, Margherita. / Mismatch repair and p53 independently affect sensitivity to N-(2- chloroethyl)-N'-cyclohexyl-N-nitrosourea. In: Clinical Cancer Research. 2000 ; Vol. 6, No. 2. pp. 671-680.
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