Does overexpression of DNA polymerase theta sensitize cancers to G-quadruplex binding drugs?

项目摘要 我的实验室研究DNA双链断裂（DSB）1。两个主要途径被用于修复DSB 2， 同源定向修复（HDR）和经典的非同源末端连接（c-NHEJ）3。替代NHEJ 当c-NHEJ被禁用时，a-NHEJ途径（a-NHEJ）起作用4，DNA聚合酶θ（polQ）是 这条路5.这首先是通过研究G-四倍体的DSB来证明的6。 DNA修复因子作为肿瘤抑制因子发挥作用7，HDR或c-NHEJ的缺陷促进基因组不稳定性 癌症8虽然polQ缺陷促进基因组不稳定性，但缺乏polQ不会促进癌症。在 事实上，polQ的缺失保护ATM缺陷小鼠免受胸腺淋巴瘤的侵袭9。此外，polQ在 许多癌症[乳腺癌、胃癌、肺癌、结肠癌、淋巴癌、皮肤癌]和过度表达与 结果较差10 -12.因此，polQ实际上与肿瘤癌基因共享一些特征。 已经表明，G-四链体结合药物吡啶抑素诱导DSB 13。我们检查了许多 c-NHEJ缺陷细胞，并确定所有核心c-NHEJ组分对最大细胞存活至关重要 在暴露于吡啶司他丁之后。相比之下（令我们惊讶的是），polQ消融显著增强了细胞存活后， 吡多司他丁暴露。 我们提出了一个模型，其中吡啶抑制素和polQ被困在G-四链体结构 在复制过程中导致复制分叉崩溃和DSB。更重要的是，这些初步 数据表明，许多过表达polQ的癌症类型可能对 针对G-四链体结构的药物，并提出了一种明显的合成致死方法， 增强针对G-四链体的疗法。

Project Summary My laboratory studies DNA double strand breaks (DSBs)1. Two primary pathways are utilized to repair DSBs2, Homology directed repair (HDR) and classical non-homologous end joining (c-NHEJ)3. An alternative NHEJ pathway (a-NHEJ) functions when c-NHEJ has been disabled4, and DNA polymerase theta (polQ) is central to this pathway5. This was first shown by studying DSBs at G-quadruplexes6. DNA repair factors function as tumor suppressors7, and defects in HDR or c-NHEJ promote genomic instability and cancer8. Although polQ deficiency promotes genomic instability, lack of polQ does not promote cancer. In fact, loss of polQ protects ATM deficient mice from thymic lymphoma9. Moreover, polQ is over-expressed in numerous cancers [breast, stomach, lung, colon, lymphoid, skin] and overexpression is highly correlated with poorer outcomes10-12. Thus, polQ actually shares some characteristics with tumor oncogenes. It has been shown that the G-quadruplex binding drug, pyridostatin, induces DSBs13. We examined numerous c-NHEJ defective cells and establish that all the core c-NHEJ components are essential for maximal cell survival after pyridostatin exposure. In contrast (and to our surprise), polQ ablation markedly enhances cell survival after pyridostatin exposure. We suggest a model whereby pyridostatin and polQ become trapped at G-quadruplex structures during replication causing replication fork collapse and DSBs. More importantly, these preliminary data suggest that the many cancer types that overexpress polQ might be particularly sensitive to drugs that target G-quadruplex structures and suggest an obvious synthetic lethal approach to enhance therapeutics that target G-quadruplexes.