Enhanced host cell reactivation capacity and expression of DNA repair genes in human breast cancer cells resistant to bi-functional alkylating agents

Lily Yen, Annie Woo, Garyfallia Christopoulopoulos, Gerald Batist, Lawrence Panasci, Rabindra Roy, Sankar Mitra, Moulay A. Alaoui-Jamali

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Human breast carcinoma (MCF7-MLNr) cells resistant to the bifunctional drugs l-phenylalanine mustard (L-PAM, 5-fold resistance), mechlorethamine (9-fold), cisplatin (3-fold), and BCNU (3-fold) were used to investigate the role of DNA repair in the development of resistance to alkylating agents. We have previously shown that neither L-PAM transport and metabolism nor glutathione-associated enzymes were altered in MCF7-MLNr cells, compared to the sensitive cells MCF7-WT. This study shows that treatment of pRSV-CAT plasmid with L-PAM at concentrations up to 1 μM proportionally inhibit the expression of chloramphenicol acetyl transferase (CAT) activity, while higher concentrations abolished CAT activity. pRSV-CAT reactivation was significantly increased when plasmid was transfected into MCF7-MLNr cells, compared to MCF7-WT cells. This indicates that resistant cells have more efficient capacity to recognize and repair L-PAM induced DNA damage. The mRNA expression of DNA nucleotide excision repair genes ERCC1, XPD (ERCC2), XPB (ERCC3), and polymerase β was found to be similar in both the MCF7-WT and MCF7-MLNr cells. Western blot analysis also reveals no difference in the expression of ERCC1, AP endonuclease, poly (ADP-ribose) polymerase, and alkyl-N-purine-DNA glycosylase proteins. The lack of correlation between enhanced host cell reactivation capacity in resistant cells, and the expression of these specific DNA repair genes suggests that proteins encoded by these genes are not rate limiting steps for resistance to bi-functional alkylating drugs in human breast cancer cells.

Original languageEnglish (US)
Pages (from-to)179-189
Number of pages11
JournalMutation Research-DNA Repair
Volume337
Issue number3
DOIs
StatePublished - Jan 1 1995

Keywords

  • Breast cancer
  • DNA repair gene
  • Drug resistance
  • Host cell reactivation

ASJC Scopus subject areas

  • Toxicology
  • Molecular Biology
  • Genetics

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