Regulation of the tumor microenvironment by DNA damage repair proteins

项目摘要 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 大约12%的ER+肿瘤完全丧失MLH 1，一种肿瘤抑制因子和错配修复蛋白。 我们先前表明ER+乳腺癌细胞中MLH 1的缺失激活HER 2，诱导对标准抗肿瘤药物的耐药性。 内分泌治疗然而，其潜在机制仍不清楚。初步数据表明， 改变HER配体分泌以介导HER 2活化的MLH 1损失。这一点特别重要，因为 另外14%的ER+患者肿瘤具有MLH 1的异质性缺失。虽然功能性后果 异质性MLH 1丢失的原因尚不清楚，MLH 1丢失在改变癌症分泌组中的作用表明， 对大部分肿瘤表型具有潜在的显著影响。 假设基于我们已发表的工作和初步数据，拟议的研究将测试假设， ER+乳腺癌中的MLH 1缺失通过选择cGAS-STING信号传导诱导HER配体分泌， 促进异质性MLH 1-肿瘤中MLH 1-和MLH 1+细胞的HER 2依赖性生长。 特定目的目的1将测试由MLH 1缺失诱导的HER配体分泌是否介导HER 2 激活，以促进内分泌治疗抗性。在这里，我们将使用体外和体内方法， 确定MLH 1- ER+乳腺癌细胞分泌的配体是否促进HER 2异源二聚化 和随后的激活，从而抵抗内分泌治疗的生长。目标2将研究其机制 将MLH 1丢失与HER配体分泌联系起来。具体地说，我们将测试是否低效的DNA损伤修复， MLH 1的缺失触发cGAS-STING分泌途径。我们还将确定cGAS-STING 激活促进HER配体分泌。目的3将检查异质性MLH 1的治疗效果。 损失我们将利用本实验室建立的体外和体内实验模型， 在具有异质性MLH 1缺失的肿瘤中的MLH 1+和MLH 1-细胞中， 对HER 2抑制剂敏感。我们还将使用数字空间分析来评估分泌组的贡献 信号模式和治疗反应在异质MLH 1肿瘤。 这项研究的结果将提出新的治疗策略，以帮助> 25，000名妇女诊断， 以异质性MLH 1丢失为特征的ER+乳腺癌患者。我们的工作还将提供新的见解 MLH 1缺失如何调节cGAS-STING通路以促进促生长肿瘤分泌组。总的来说， 这项研究的结果将为MLH 1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.