Abstract B43: RECQ1, a breast cancer susceptibility gene, is upregulated by cancer therapeutics in a p53-dependent manner

Sensitivity of cancer cells to DNA-damaging chemotherapeutics is determined by DNA repair processes. Consequently, cancer cells may upregulate expression of certain DNA repair genes as a mechanism to promote chemoresistance. Here, we report identification of RECQ1, a breast cancer susceptibility gene that encodes the most abundant RecQ helicase in humans, as a p53-regulated target potentially acting as a defense against DNA-damaging agents. Quantitative RT-PCR analysis in a variety of cancer cell lines revealed RECQ1 to be upregulated following DNA damage, which was confirmed by Western blot experiments. Significant increase in RECQ1 mRNA level was observed following treatment with alkylating agent methylmethanesulfonate (MMS) as well as the representative chemotherapeutic drugs doxorubicin, temozolomide and fotemustine. Upregulation of RECQ1 expression also appeared to depend on the nature of DNA lesion. Induction of RECQ1 by genotoxins requires p53 since it was observed in p53 wild-type but not in p53 null cells. Consistent with that, the RECQ1 promoter is bound by endogenous p53 and is responsive to p53 in luciferase assay. Knocking down RECQ1 expression in cancer cells resulted in increased sensitivity to MMS, fotemustine and temozolomide supporting the hypothesis that RECQ1 is involved in the recovery of cells from DNA damage. Notably, RECQ1 is frequently overexpressed and amplified in a variety of cancers. As RECQ1 efficiently protects cells from genomic instability thr...
Source: Molecular Cancer Research - Category: Cancer & Oncology Authors: Tags: Exploiting Repair Defects in the Tumor Microenvironment: Poster Presentations - Proffered Abstracts Source Type: research