Acquired Resistance to TGFBR1 inhibitors and cancer stem cell outgrowth

描述(申请人提供)：我们最近证明，在小分子转化生长因子受体1抑制剂体内慢性抑制转化生长因子信号通路会导致小鼠皮肤癌模型中耐药的化学启动癌的生长。这是第一个关于获得性对转化生长因子抑制剂产生耐药性的报告。此外，这些耐药癌具有侵袭性表型，并显示皮肤干细胞标记物表达的基因丰富。目前建议的目标是确定这种指示癌症干细胞的分子图谱是否源于功能干细胞舱的扩张，并阐明获得耐药的分子机制。需要检验的假设是，慢性药物抑制转化生长因子信号通路会导致耐药状态，导致结构性升高的Smad2/3信号，支持CSC间隔室的扩张。在目标1中，我们计划使用体内和体外方法在化学诱导致癌的小鼠皮肤模型中证明这一假说。在目标2中，我们将通过对目标基因外显子的超深度测序对档案组织进行突变筛选，以及通过在体外进行Smad2激活激酶的筛选，来研究导致获得性耐药和CSC生长的分子机制。了解对转化生长因子阻断疗法产生获得性耐药的分子机制，有可能改进治疗策略和下一代药物设计。此外，由于CSCs和转化生长因子信号之间的密切联系，这一知识很有希望为CSC维持的分子调控提供洞察力，并可能为攻击CSCs提供新的药物靶点。 与公共卫生相关：我们最近证明，癌细胞可以对一种新的抗转化生长因子药物产生抗药性。这种耐药性似乎支持癌症干细胞的生长，而癌症干细胞是维持肿瘤、允许肿瘤扩散和导致治疗后癌症复发的主要罪魁祸首。我们打算在分子水平上找出癌症是如何逃避这种药物的，这将为了解癌症干细胞生物学提供洞察，并为攻击癌症干细胞提供新的靶点。

DESCRIPTION (provided by applicant): We have recently demonstrated that chronic inhibition of the Transforming Growth Factor-¿ (TGF¿) signaling pathway by a small molecule TGF¿R1 inhibitor in vivo leads to the outgrowth of drug resistant chemically-initiated carcinomas in a mouse skin cancer model. This is the first report of development of acquired drug resistance to a TGF¿ inhibitor. Moreover, these drug resistant carcinomas have an aggressive phenotype and show gene enrichment for expression of skin stem cell markers. The goal of the current proposal is to determine whether this molecular profile, indicative of a cancer stem cell, is due to expansion of the functional stem cell compartment, and to elucidate the molecular mechanisms for acquisition of drug resistance. The hypothesis to be tested is that chronic pharmacological suppression of the TGF¿ signaling pathway induces a drug-resistant state resulting in constitutively elevated Smad2/3 signaling that supports expansion of the CSC compartment. In Aim 1 we plan to prove this hypothesis using both in vivo and in vitro approaches in the mouse skin model of chemically-induced carcinogenesis. In Aim 2, we will address the molecular mechanisms responsible for acquired drug resistance and CSC outgrowth by mutation screening of archival tissue using ultra-deep sequencing of the exons of target genes, and by undertaking screens for Smad2 activating kinases in vitro. Understanding the molecular mechanisms of acquired drug resistance to TGF¿ blocking therapies has the potential to improve treatment strategies and next generation drug design. In addition, because of the intimate association between CSCs and TGF¿ signaling, this knowledge has great promise to provide insights into the molecular regulation of CSC maintenance and could provide novel druggable targets for attacking CSCs. PUBLIC HEALTH RELEVANCE: We have recently demonstrated that cancer cells can acquire resistant to a new anti-TGF¿ drug. This resistance appears to support outgrowth of cancer stem cells that are the main villains in maintaining the tumor, allowing tumor spread and causing cancer recurrence after therapy. We intend to find out how the cancer evades this drug at the molecular level, which will provide insight into cancer stem cell biology and provide new targets for attacking cancer stem cells.