Natural flavonoids have diverse pharmacological activities, including anti-oxidative, anti-inflammatory, and anti-cancer activities. In this study, we investigated the molecular mechanism underlying the action of 5-methoxyflavanone (5-MF) which has a strong bioavailability and metabolic stability. Our results show that 5-MF inhibited the growth and clonogenicity of HCT116 human colon cancer cells, and that it activated DNA damage responses, as revealed by the accumulation of p53 and the phosphorylation of DNA damage-sensitive proteins, including ataxia-telangiectasia mutated (ATM) at Ser1981, checkpoint kinase 2 (Chk2) at Thr68, and histone H2AX at Ser139. 5-MF-induced DNA damage was confirmed in a comet tail assay. We also found that 5-MF increased the cleavage of caspase-2 and -7, leading to the induction of apoptosis. Pretreatment with the ATM inhibitor KU55933 enhanced 5-MF-induced γ-H2AX formation and caspase-7 cleavage. HCT116 cells lacking p53 (p53(-/-)) or p21 (p21(-/-)) exhibited increased sensitivity to 5-MF compared to wild-type cells. 5-MF further induced autophagy via an ERK signaling pathway. Blockage of autophagy with the MEK inhibitor U0126 potentiated 5-MF-induced γ-H2AX formation and caspase-2 activation. These results suggest that a caspase-2 cascade mediates 5-MF-induced anti-tumor activity, while an ATM/Chk2/p53/p21 checkpoint pathway and ERK-mediated autophagy act as a survival program to block caspase-2-mediated apoptosis induced by 5-MF.

中文翻译：

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5-甲氧基黄酮在HCT116人结肠癌细胞中诱导G2 / M期细胞周期停滞，凋亡和自噬。

天然类黄酮具有多种药理活性，包括抗氧化，抗炎和抗癌活性。在这项研究中，我们调查了具有强大的生物利用度和代谢稳定性的5-甲氧基黄酮（5-MF）作用的分子机制。我们的结果表明，5-MF抑制了HCT116人结肠癌细胞的生长和克隆形成，并激活了DNA损伤反应，这通过p53的积累和DNA损伤敏感蛋白的磷酸化（包括共济失调-毛细血管扩张突变（ （ATM）位于Ser1981，检查点激酶2（Chk2）位于Thr68，而组蛋白H2AX位于Ser139。在彗尾实验中证实了5-MF诱导的DNA损伤。我们还发现5-MF增加了对caspase-2和-7的切割，从而诱导了细胞凋亡。用ATM抑制剂KU55933预处理可增强5-MF诱导的γ-H2AX的形成和caspase-7的裂解。与野生型细胞相比，缺少p53（p53（-/-））或p21（p21（-/-））的HCT116细胞对5-MF的敏感性更高。5-MF通过ERK信号通路进一步诱导自噬。用MEK抑制剂U0126阻断自噬可增强5-MF诱导的γ-H2AX的形成和caspase-2的活化。这些结果表明，caspase-2级联介导5-MF诱导的抗肿瘤活性，而ATM / Chk2 / p53 / p21检查点途径和ERK介导的自噬可作为阻止caspase-2介导的凋亡诱导的生存程序。通过5-MF。5-MF通过ERK信号通路进一步诱导自噬。用MEK抑制剂U0126阻断自噬可增强5-MF诱导的γ-H2AX的形成和caspase-2的活化。这些结果表明，caspase-2级联介导5-MF诱导的抗肿瘤活性，而ATM / Chk2 / p53 / p21检查点途径和ERK介导的自噬可作为阻止caspase-2介导的凋亡诱导的生存程序。通过5-MF。5-MF通过ERK信号通路进一步诱导自噬。用MEK抑制剂U0126阻断自噬可增强5-MF诱导的γ-H2AX的形成和caspase-2的活化。这些结果表明，caspase-2级联介导5-MF诱导的抗肿瘤活性，而ATM / Chk2 / p53 / p21检查点途径和ERK介导的自噬可作为阻止caspase-2介导的凋亡诱导的生存程序。通过5-MF。