■共济失调毛细血管扩张突变(ATM)激酶是DNA损伤反应(DDR)信号通路的中央调节因子,它的功能对于维持协调细胞过程网络的细胞中的基因组稳定性至关重要,包括DNA复制,DNA修复,和细胞周期进程。ATM在人类癌症中经常发生突变,大约3%的肺癌在ATM中有双等位基因突变,即,包括3.5%的肺腺癌(LUAD)和1.4%的肺鳞癌(LUSC)。
■我们研究了在肺癌中靶向DDR途径作为潜在治疗方法的潜力。在这种情况下,我们检查了尼拉帕尼单药治疗ATM丢失是否具有合成致死性。该探索涉及在人结肠直肠腺癌细胞系DLD-1中使用包含通过CRISPR/Cas9基因敲除技术产生的hATM纯合(-/-)和杂合(+/-)的hATM敲除(KO)等基因细胞系。随后,我们将研究扩展到非小细胞肺癌(NSCLC)患者来源的异种移植(PDX)模型,以进一步验证在ATM突变NSCLC模型中聚ADP-核糖聚合酶抑制剂(PARPi)合成致死性.
■这里,我们认为DLD-1中的双等位基因hATM缺失(-/-)会损害同源重组(HR)修复功能并使细胞对PARPi敏感,尼拉帕利。尼拉帕尼还在三分之一携带有害双等位基因ATM突变的NSCLCPDX模型中引起显著的肿瘤消退。在hATM(-/-)DLD-1细胞系和PARPi敏感的ATM突变NSCLCPDX模型中,hATM(-/-)的缺失与低BRCA1和BRCA2蛋白表达相关。提示对HR介导的DNA检查点信号传导受损的下游影响。进一步的分析表明,ATM的丢失导致抑制MRN(Mre11-Rad50-NBS1)复合蛋白的磷酸化,这是ATM介导的p53、BRCA1和CHK2下游磷酸化所必需的。
■放在一起,我们的研究结果强调,尼拉帕尼在ATM缺陷型肿瘤中的合成致死性可以通过对BRCA1/2表达的调节及其对HR功能的影响的后续作用来调节.
UNASSIGNED: Ataxia telangiectasia-mutated (ATM) kinase is a central regulator of the DNA damage response (DDR) signaling pathway, and its function is critical for the maintenance of genomic stability in cells that coordinate a network of cellular processes, including DNA replication, DNA repair, and cell cycle progression. ATM is frequently mutated in human cancers, and approximately 3% of lung cancers have biallelic mutations in ATM, i.e., including 3.5% of lung adenocarcinomas (LUAD) and 1.4% of lung squamous cell carcinomas (LUSC).
UNASSIGNED: We investigated the potential of targeting the DDR pathway in lung cancer as a potential therapeutic approach. In this context, we examined whether ATM loss is synthetically lethal with niraparib monotherapy. This exploration involved the use of hATM knockout (KO) isogenic cell lines containing hATM homozygous (-/-) and heterozygous (+/-) generated via CRISPR/Cas9 gene knockout technology in DLD-1, a human colorectal adenocarcinoma cell line. Subsequently, we extended our investigation to non-small cell lung cancer (NSCLC) patient derived xenograft (PDX) models for further validation of poly ADP-ribose polymerase inhibitor (PARPi) synthetic lethality in ATM mutant NSCLC models.
UNASSIGNED: Here, we demonstared that biallelic hATM deletion (-/-) in DLD-1 impairs homologous recombination (HR) repair function and sensitizes cells to the PARPi, niraparib. Niraparib also caused significant tumor regression in one-third of the NSCLC PDX models harboring deleterious biallelic ATM mutations. Loss of hATM (-/-) was concomitantly associated with low BRCA1 and BRCA2 protein expression in both the hATM (-/-) DLD-1 cell line and PARPi-sensitive ATM mutant NSCLC PDX models, suggesting a downstream effect on the impairment of HR-mediated DNA checkpoint signaling. Further analysis revealed that loss of ATM led to inhibition of phosphorylation of MRN (Mre11-Rad50-NBS1) complex proteins, which are required for ATM-mediated downstream phosphorylation of p53, BRCA1, and CHK2.
UNASSIGNED: Taken together, our findings highlight that the synthetic lethality of niraparib in ATM-deficient tumors can be regulated through a subsequent effect on the modulation of BRCA1/2 expression and its effect on HR function.