BACKGROUND & OBJECTIVE: Nucleotide excision repair (NER) is a multi-enzyme DNA repair system in eukaryotes. Several NER genes in this system including XPA, XPB, ERCC1, and ERCC2 (XPD) have been implicated in anticancer drug resistance in human tumor cells. This study was designed to investigate the relationship between the expression of NER protein and the drug-resistance of human tumor cell lines. METHODS: In this study, The authors assessed the levels of the above mentioned proteins, by utilizing Western blot analysis, in the USA National Cancer Institute (NCI) panel of 60 human tumor cell lines and correlated to the cytotoxicity patterns of 170 compounds that constitute the standard agent (SA) database. RESULTS: The ERCC1, XPB, and XPD protein expression patterns yielded significant negative Pearson correlations with 13, 17, and 32 out of the 170 compounds, respectively (P < 0.05). XPA produced a random assortment of negative and positive correlations and did not appear to confer an overall resistance or sensitivity to these drugs. Protein expression was also compared with a pre-defined categorisation of the standard agents into six mechanism-of-action (MOA) groups resulting in an inverse association between XPD and alkylating agent sensitivity. CONCLUSION: Our present data demonstrate that XPD protein levels correlate with resistance to alkylating agents in human tumor cell lines, suggesting that XPD plays an important role in the development of this resistance.
BACKGROUND & OBJECTIVE: Nucleotide excision repair (NER) is a multi-enzyme DNA repair system in eukaryotes. Several NER genes in this system including XPA, XPB, ERCC1, and ERCC2 (XPD) have been implicated in anticancer drug resistance in humantumor cells. This study was designed to investigate the relationship between the expression of NER protein and the drug-resistance of humantumor cell lines. METHODS: In this study, The authors assessed the levels of the above mentioned proteins, by utilizing Western blot analysis, in the USA National Cancer Institute (NCI) panel of 60 humantumor cell lines and correlated to the cytotoxicity patterns of 170 compounds that constitute the standard agent (SA) database. RESULTS: The ERCC1, XPB, and XPD protein expression patterns yielded significant negative Pearson correlations with 13, 17, and 32 out of the 170 compounds, respectively (P < 0.05). XPA produced a random assortment of negative and positive correlations and did not appear to confer an overall resistance or sensitivity to these drugs. Protein expression was also compared with a pre-defined categorisation of the standard agents into six mechanism-of-action (MOA) groups resulting in an inverse association between XPD and alkylating agent sensitivity. CONCLUSION: Our present data demonstrate that XPD protein levels correlate with resistance to alkylating agents in humantumor cell lines, suggesting that XPD plays an important role in the development of this resistance.