Regulation of the tumor microenvironment by DNA damage repair proteins

项目总结 研究背景ER+乳腺癌占当今世界诊断的浸润性乳腺癌病例的2/3。在……里面 患者中，约12%的ER+肿瘤中肿瘤抑制因子和错配修复蛋白MLH1完全缺失。 我们之前发现，ER+乳腺癌细胞中MLH1的缺失会激活HER2，从而诱导对标准药物的耐药性 内分泌治疗。然而，其潜在的机制仍不清楚。初步数据支持 MLH1缺失改变HER2配体的分泌以调节HER2的激活。这特别令人感兴趣，因为 另有14%的ER+患者肿瘤有MLH1的异质性丢失。尽管功能后果 异质性MLH1丢失的情况尚不清楚，MLH1丢失在改变癌症分泌组中的作用提示 对大块肿瘤表型有潜在的重大影响。 假设基于我们已发表的工作和初步数据，拟议的研究将检验以下假设 ER+乳腺癌中MLH1缺失通过加入cGAS-STING信号诱导其配体的分泌 促进异种MLH1-肿瘤中MLH1-和MLH1+细胞的HER2依赖生长。 特异性靶标Aim 1将测试MLH1缺失诱导的HER2配体的分泌是否介导HER2 激活促进内分泌治疗抵抗。在这里，我们将使用体外和体内两种方法来 确定MLH1-ER+乳腺癌细胞分泌的配体是否促进HER2异二聚化 并随之而来的激活，从而内分泌治疗抵抗生长。目标2将研究这一机制 将MLH1的缺失与她的配体分泌联系起来。具体地说，我们将测试低效的DNA损伤修复在 MLH1的缺失触发了cGAS刺痛的分泌途径。我们还将确定cGAS如何刺痛 激活促进了她的配体分泌。AIM 3将检查异种MLH1的治疗效果 损失。利用我实验室建立的体外和体内实验模型，我们将测试HER2的激活 在具有异质性MLH1缺失的肿瘤中的MLH1+和MLH1-细胞中，这些肿瘤呈现为全局 对HER2抑制剂敏感。我们还将使用数字空间轮廓来评估分泌组的贡献 异质性MLH1-肿瘤的信号模式和治疗反应。 影响这项研究的结果将提出新的治疗策略，帮助&gt；25,000名被诊断为 ER+乳腺癌以MLH1异质性丢失为特征。我们的工作还将提供新的见解 MLH1缺失如何调节cGAS-STING途径，促进促生长的肿瘤分泌组。总的来说， 这项研究的结果将为MLH1缺失如何促进癌症表型提供新的见解。

PROJECT SUMMARY Background ER+ breast cancer accounts for 2/3 of invasive breast cancer cases diagnosed in the world today. In patients, ~12% of ER+ tumors have complete loss of MLH1, a tumor suppressor and mismatch repair protein. We previously showed that MLH1 loss in ER+ breast cancer cells activates HER2 to induce resistance to standard endocrine therapy. However, the underlying mechanism remains unknown. Preliminary data support a role for MLH1 loss in altering secretion of HER ligands to mediate HER2 activation. This is of particular interest because an additional 14% of ER+ patient tumors have heterogeneous loss of MLH1. Although the functional consequence of heterogeneous MLH1 loss is as yet unknown, a role for MLH1 loss in altering the cancer secretome suggests a potentially significant impact on bulk tumor phenotypes. Hypothesis Based on our published work and preliminary data, the proposed study will test the hypothesis that MLH1 loss in ER+ breast cancer induces secretion of HER ligands, by co-opting cGAS-STING signaling, to promote HER2-dependent growth of both MLH1– and MLH1+ cells in heterogeneously MLH1– tumors. Specific Aims Aim 1 will test whether the secretion of HER ligands induced by MLH1 loss mediates HER2 activation to promote endocrine therapy resistance. Here, we will use both in vitro and in vivo approaches to determine whether the ligands secreted by MLH1- ER+ breast cancer cells promote HER2 heterodimerization and consequent activation, and thereby endocrine therapy resistant growth. Aim 2 will investigate the mechanism linking MLH1 loss to HER ligand secretion. Specifically, we will test whether inefficient DNA damage repair in the absence of MLH1 triggers the cGAS-STING secretory pathway. We will also determine how cGAS-STING activation promotes HER ligand secretion. Aim 3 will examine the therapeutic impact of heterogeneous MLH1 loss. Using in vitro and in vivo experimental models established in my lab, we will test whether HER2 activation in both MLH1+ and MLH1- cells in tumors with heterogeneous MLH1 loss renders these tumors globally susceptible to HER2 inhibitors. We will also use digital spatial profiling to assess the contribution of the secretome to signaling patterns and therapeutic response in heterogeneously MLH1- tumors. Impact The results of this study will present new therapeutic strategies to help >25,000 women diagnosed each year with ER+ breast cancer characterized by heterogeneous MLH1 loss. Our work will also provide novel insight into how MLH1 loss modulates the cGAS-STING pathway to promote a pro-growth tumor secretome. Overall, results from this study will shed new insight into the how MLH1 loss promotes cancer phenotypes.