Acquired Resistance to TGFBR1 inhibitors and cancer stem cell outgrowth

描述（由申请人提供）：我们最近已经证明，在小鼠皮肤癌模型中，小分子TGF β 1抑制剂对转化生长因子-β（TGF β）信号通路的体内慢性抑制导致耐药化学引发的癌的生长。这是第一次报告的发展获得性耐药性的TGF抑制剂。此外，这些耐药癌具有侵袭性表型，并显示皮肤干细胞标志物表达的基因富集。目前的建议的目标是确定是否这种分子概况，癌症干细胞的指示，是由于功能性干细胞室的扩展，并阐明获得耐药性的分子机制。待检验的假设是TGF β信号传导途径的慢性药理学抑制诱导耐药状态，导致组成性升高的Smad 2/3信号传导，其支持CSC隔室的扩增。在目标1中，我们计划在化学诱导的致癌作用的小鼠皮肤模型中使用体内和体外方法来证明这一假设。在目标2中，我们将通过使用靶基因外显子的超深度测序对存档组织进行突变筛选，并通过在体外筛选Smad 2激活激酶，来解决获得性耐药性和CSC生长的分子机制。了解获得性耐药的分子机制TGF β阻断疗法有可能改善治疗策略和下一代药物设计。此外，由于CSC和TGF β信号传导之间的密切联系，这些知识很有希望为CSC维持的分子调控提供见解，并可以为攻击CSC提供新的药物靶点。

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.