Cohn Gabriel M, Daniel Colin J, Eng Jennifer R, Sun Xiao-Xin, Pelz Carl, Chin Koei, Smith Alexander, Lopez Charles D, Brody Jonathan R, Dai Mu-Shui, Sears Rosalie C
Department of Molecular and Medical Genetics, School of Medicine, Oregon Health and Science University, Portland, OR, USA.
Brenden-Colson Center for Pancreatic Care, Oregon Health and Science University, Portland, OR, USA.
bioRxiv. 2025 Mar 20:2025.03.19.644227. doi: 10.1101/2025.03.19.644227.
Genomic instability is a hallmark of cancer, driving oncogenic mutations that enhance tumor aggressiveness and drug resistance. MYC, a master transcription factor that is deregulated in nearly all human tumors, paradoxically induces replication stress and associated DNA damage while also increasing expression of DNA repair factors and mediating resistance to DNA-damaging therapies. Emerging evidence supports a non-transcriptional role for MYC in preserving genomic integrity at sites of active transcription and protecting stalled replication forks under stress. Understanding how MYC's genotoxic and genoprotective functions diverge may reveal new therapeutic strategies for MYC-driven cancers. Here, we identify a non-canonical role of MYC in DNA damage response (DDR) through its direct association with DNA breaks. We show that phosphorylation at serine 62 (pS62-MYC) is crucial for the efficient recruitment of MYC to damage sites, its interaction with repair factors BRCA1 and RAD51, and effective DNA repair to support cell survival under stress. Mass spectrometry analysis with MYC-BioID2 during replication stress reveals a shift in MYC's interactome, maintaining DDR associations while losing transcriptional regulators. These findings establish pS62-MYC as a key regulator of genomic stability and a potential therapeutic target in cancers.
基因组不稳定是癌症的一个标志,它驱动致癌突变,增强肿瘤的侵袭性和耐药性。MYC是一种在几乎所有人类肿瘤中均失调的主转录因子,矛盾的是,它既能诱导复制应激和相关的DNA损伤,同时又能增加DNA修复因子的表达并介导对DNA损伤疗法的抗性。新出现的证据支持MYC在维持活跃转录位点的基因组完整性以及在应激条件下保护停滞的复制叉方面具有非转录作用。了解MYC的基因毒性和基因保护功能如何不同,可能会揭示针对MYC驱动的癌症的新治疗策略。在这里,我们通过MYC与DNA断裂的直接关联,确定了MYC在DNA损伤反应(DDR)中的非经典作用。我们表明,丝氨酸62位点的磷酸化(pS62-MYC)对于将MYC有效招募到损伤位点、其与修复因子BRCA1和RAD51的相互作用以及在应激条件下支持细胞存活的有效DNA修复至关重要。在复制应激期间用MYC-BioID2进行的质谱分析揭示了MYC相互作用组的转变,即维持DDR关联同时失去转录调节因子。这些发现确立了pS62-MYC作为基因组稳定性的关键调节因子以及癌症中的潜在治疗靶点。