| Abstract Tangeretin, a polymethoxyflavone found in citrus peel, has been shown to have anti-atherogenic, anti-inflammatory, and anti-carcinogenic properties. However, the underlying target pathways are not fully characterized. We investigated the tangeretin sensitivity of yeast (Saccharomyces cerevisiae) mutants for DNA damage response or repair pathways. We found that tangeretin treatment significantly reduced (p < 0.05) survival rate, induced preferential G1 phase accumulation, and elevated the DNA double-strand break (DSB) signal γH2A in DNA repair-defective sgs1Δ cells, but had no obvious effects on wild-type cells or mutants of the DNA damage checkpoint (including tel1∆, sml1∆ mec1∆, sml1∆ mec1∆ tel1∆, and rad9∆ mutants). Additionally, microarray data indicated that tangeretin treatment up-regulates genes involved in nutritional processing and down-regulates genes related to RNA processing in sgs1∆ mutants. These results suggest tangeretin may sensitize SGS1 deficient cells by increasing a marker of DNA damage, and by inducing G1 arrest and possibly metabolic stress. Thus, tangeretin may be suitable for chemosensitization of cancer cells lacking DSB-repair ability.
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