Journal Article

HIF1α regulated expression of XPA contributes to cisplatin resistance in lung cancer

Yanbin Liu, Amanda M. Bernauer, Christin M. Yingling and Steven A. Belinsky

in Carcinogenesis

Volume 33, issue 6, pages 1187-1192
Published in print June 2012 | ISSN: 0143-3334
Published online March 2012 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgs142
HIF1α regulated expression of XPA contributes to cisplatin resistance in lung cancer

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Factors regulating nucleotide excision repair probably contribute to the heterogenous response of advanced stage lung cancer patients to drugs such as cisplatin. Studies to identify the genes in the nucleotide excision repair pathway most closely associated with resistance to cisplatin have not been conclusive. We hypothesized that Xeroderma pigmentosum complementation group A (XPA), because of its dual role in sensing and recruiting other DNA repair proteins to the damaged template, would be critical in defining sensitivity to cisplatin. Studies were conducted to identify factors regulating transcription of XPA, to assess its role in modulating sensitivity to cisplatin and its expression in primary lung tumors. Hypoxia-inducible factor 1 alpha (HIF1α) subunit was found to bind with strong affinity to a hypoxia response element sequence in the promoter of XPA. Modulating expression of HIF1α by small interfering RNA or cobalt chloride markedly reduced or increased transcription of XPA in lung cancer cell lines, respectively. Protein levels of XPA were strongly correlated with sensitivity to cisplatin (r = 0.88; P < 0.001) in cell lines and sensitivity could be increased by small interfering RNA depletion of XPA. Expression of XPA determined in 54 primary lung tumors was elevated on average 5.2-fold when compared with normal bronchial epithelial cells and correlated with levels of HIF1α (r = 0.58; P < 0.01). Together, these studies identify XPA as a novel target for regulation by HIF1α whose modulation could impact lung cancer therapy.

Journal Article.  4390 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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