Chen Chuanhui, Zhou Pinglang, Zhang Zhizhe, Liu Yu
Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.
Clin Exp Pharmacol Physiol. 2022 Jul;49(7):740-747. doi: 10.1111/1440-1681.13646. Epub 2022 May 10.
The recurrent mutation (S34F) in splicing factor U2AF1 is frequently observed in lung adenocarcinoma, but its function remains largely unknown. To determine the mechanistic basis and consequences of U2AF1 mutations, we established non-small cell lung carcinoma A549 cell lines with exogenous expression of wildtype (U2AF1-WT) or mutant (U2AF1-S34F). Splicing analysis revealed that U2AF1-S34F mainly caused aberrant exon usage and affected splicing of numerous DNA damage repair genes. Compared to A549 cells expressing U2AF1-WT, cells expressing U2AF1-S34F showed enhanced DNA damage and cell death in response to ATR inhibitors (ATRi). Mechanistically, U2AF1-S34F induced mis-splicing and downregulation of a key homologous recombination protein RAD51. Overexpression of RAD51 could largely rescue the defective DNA damage response in cells expressing U2AF1-S34F. Moreover, A549 cells expressing U2AF1-S34F, but not U2AF1-WT, were highly sensitive to treatment even with low dose of RAD51 inhibitor on ATRi-induced DNA damage. Our results suggest that U2AF1-S34F causes mis-splicing of DNA damage repair factors in lung cancer and sensitizes cells to RAD51 inhibition.
剪接因子U2AF1中的复发性突变（S34F）在肺腺癌中经常被观察到，但其功能在很大程度上仍不清楚。为了确定U2AF1突变的机制基础和后果，我们建立了非小细胞肺癌A549细胞系，使其外源性表达野生型（U2AF1-WT）或突变型（U2AF1-S34F）。剪接分析显示，U2AF1-S34F主要导致外显子使用异常，并影响众多DNA损伤修复基因的剪接。与表达U2AF1-WT的A549细胞相比，表达U2AF1-S34F的细胞在对ATR抑制剂（ATRi）的反应中表现出增强的DNA损伤和细胞死亡。从机制上讲，U2AF1-S34F诱导关键同源重组蛋白RAD51的错配剪接和下调。RAD51的过表达可以在很大程度上挽救表达U2AF1-S34F的细胞中缺陷的DNA损伤反应。此外，即使使用低剂量的RAD51抑制剂处理，表达U2AF1-S34F而不是U2AF1-WT的A549细胞对ATRi诱导的DNA损伤也高度敏感。我们的结果表明，U2AF1-S34F导致肺癌中DNA损伤修复因子的错配剪接，并使细胞对RAD51抑制敏感。
