Vulnerabilities of MMR-deficient glioblastoma

胶质母细胞瘤(Gbm)是最常见和最致命的脑癌，对ALL具有先天或适应性抵抗。 现有的治疗方法。GBM对替莫唑胺产生耐药性的一个重要机制是 治疗中使用的一线化疗源于MSH6和MSH2等关键基因的突变 在DNA错配修复(MMR)中--一种在结肠癌和其他癌症中也发现的机制。这些MMR缺乏 基底膜变得高度突变，尤其具有侵袭性，并对许多化疗药物产生抗药性，以及 迫切需要找出对他们有效的治疗方法。而最近的一份报告描述了 2例对免疫治疗检查点有反应的儿童MMR缺陷、高突变的GBM 我们自己和其他人的临床经验一致表明，成年患者缺乏反应。 用这些药物治疗MMR缺陷、高突变的GBM。这项提案测试了新的治疗方法 寻找MMR缺乏、高度突变的基底膜的方法，并使用独特的工具来做到这一点。我们的初步研究 对先前关于钙通道抑制对MMR缺乏症的可能活性的报道进行了扩展 癌症首次表明，不同钙通道的联合抑制剂--羧胺三唑 (CaI)、米贝拉地尔和维拉帕米-对MMR缺陷的GBM株系具有优先和协同活性 而不是父母的关系。此外，我们的初步结果进一步表明，转化生长因子-β是这方面的潜在靶点。 化疗药物伊立替康和降胆固醇的他汀类药物可以重新用于转化生长因子- β抑制剂对Mmr缺陷的基底膜具有优先活性。这些治疗策略正在接受测试 对照每一个包括亲本系和从其得到的MMR缺陷系的匹配的GBM系组， 以及自发产生MMR缺乏症的GBM系和控制GBM系的组。MMR- 每个缺陷系都有MSH6或MSH2不足，源于体内继发的突变 替莫唑胺处理或来自稳定表达的shRNA。本提案将使用这些匹配的 钙通道阻滞剂联合转化生长因子-β对亲本/基质金属硫蛋白缺陷型基底膜细胞系的影响 体外和体内抑制作用。此外，鉴于MMR缺乏症和过度突变都具有治疗作用 方法很可能会影响抗GBM的免疫反应，我们还将开发一种免疫活性 建立MMR缺陷型GBM小鼠模型，以验证上述效应。既有针对性又不偏不倚的机理研究 将进行，包括评估两种治疗策略和 磷酸蛋白质组学和rna-seq分析。拟议的研究将产生新的生物和治疗方法。 这些见解可能会迅速影响MMR缺陷、高突变的GBM和其他癌症的治疗。

Glioblastoma (GBM) is the most common and lethal brain cancer, with inherent or adaptive resistance to all existing treatments. One important mechanism by which GBM develops resistance to temozolomide, the frontline chemotherapy used in its treatment, stems from mutations in genes such as MSH6 and MSH2 critical in DNA mismatch repair (MMR)—a mechanism found in colon and other cancers as well. These MMR-deficient GBMs become hypermutated and particularly aggressive as well as resistant to many chemotherapies, and there is a pressing need to identify therapies that are effective against them. While a recent report describes two cases of pediatric MMR-deficient, hypermutated GBM that responded to immunotherapeutic checkpoint inhibitors, our own and others’ clinical experience has uniformly indicated a lack of responses in adult patients with MMR-deficient, hypermutated GBM treated with these agents. This proposal tests novel therapeutic approaches to MMR-deficient, hypermutated GBMs and uses unique tools to do so. Our preliminary studies expand on prior reports suggesting possible activity of calcium channel inhibition against MMR-deficient cancers to show for the first time that combining inhibitors of different calcium channels—carboxyamidotriazole (CAI), mibefradil, and verapamil—has preferential and synergistic activity against MMR-deficient GBM lines versus parental lines. In addition, our preliminary results further suggest TGF-β as a potential target in this setting, and that the chemotherapy drug irinotecan and the anti-cholesterol statins can be repurposed as TGF- β inhibitors with preferential activity against MMR-deficient GBM. These therapeutic strategies are being tested against matched sets of GBM lines that each include a parental line and an MMR-deficient line derived from it, as well as sets of GBM lines that spontaneously developed MMR deficiency and control GBM lines. The MMR- deficient lines each have MSH6 or MSH2 insufficiency derived either from mutations secondary to in vivo temozolomide treatment or from stable expression of shRNA. This proposal will use these matched parental/MMR-deficient GBM lines to test the effects of calcium channel blockade combinations and TGF-β inhibition in vitro and in vivo. In addition, given that MMR deficiency and hypermutation and both therapeutic approaches are likely to impact the anti-GBM immune response, we will also develop an immunocompetent mouse model of MMR-deficient GBM to test these effects. Both targeted and unbiased studies of mechanism will be performed, including assessing connections between the two therapeutic strategies and phosphoproteomic and RNA-seq analyses. The proposed studies will yield new biologic and therapeutic insights that could rapidly impact the treatment of MMR-deficient, hypermutated GBM and other cancers.