Abstract 4228: Aryl hydrocarbon receptor nuclear translocator is associated with cisplatin resistance in cancer cells

Abstract

Abstract The (ARNT) belongs to the basic-helix-loop-helix (bHLH) transcription factors containing Per-Arnt-Sim (PAS) domain. In addition to forming heterodimers with many other bHLH-PAS proteins, including the aryl hydrocarbon receptor (AhR) and hypoxia-inducible factor 1α, ARNT can also form homodimers. Our previous study had shown that ARNT is a new factor involved in EGF regulated COX-2 gene expression under normoxia involving tumorigenesis in cervical cancer tissues. Resistence to cisplatin is often observed in cervical cancer therapy. Here we showed that ARNT expression is critical for cisplatin resistance. Specifically, we showed that in HeLa cervical cancer lines, cisplatin decreased ARNT expression level. Over-expression of ARNT rendered HeLa cells resistant to cisplatin. In addition, inhibition of ARNT by small interfering RNA silencing increased cisplatin induced cell death by activation of caspase 3 and sensitized drug resistant cells to cisplatin. Using ARNT deficient and ARNT fully expressed cell lines showed that induction of apoptosis by cisplatin correlates with ARNT. Importantly down regulation of ARNT decreased drug efflux pump protein MDR1 expression, suggesting that MDR1 gene expression depends on ARNT activity. In conclusion, ARNT mediates the efflux of cisplatin and has a functional role in cervical cancer cell sensitivity to cisplatin. In a xenograft analysis of SCID mice, cisplatin also efficiently inhibited ARNT-deficient tumor formation. These results suggest that targeting ARNT could overcome cisplatin resistance in human cervical cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4228. doi:1538-7445.AM2012-4228