Regulating Gli Function in Hair Follicle Progenitors

描述（由申请人提供）：刺猬（Hh）信号已成为人类癌变的关键生长途径，不适当的Hh靶基因激活可驱动皮肤基底细胞癌（BCCs）等肿瘤的生长。5ARO54780的实验支持促进了FDA批准首个针对Smoothened （Smo）受体的治疗。虽然新生肿瘤有应答，但耐药似乎很常见，这重申了开发针对Smo. 5ARO54780下游Gli转录因子的新疗法的必要性，在之前的资助期内，重点关注调节Gli活性的因子，并显示了初级纤毛和基础体相关的缺失转移的重要性。此外，通过蛋白质组学筛选鉴定可用药成分，分离出致癌极性激酶aPKC-?/？并证明了aPKC-?/？在hedgehog信号传导、BCC肿瘤生长和Smo抑制剂耐药性中发挥关键作用。在肿瘤中，aPKC-?/？磷酸化并激活DNA结合域Gli T304的调控区域内的Gli1。相比之下，DNA结合域连接区域的磷酸化似乎会抑制功能，这揭示了我们对DNA结合域修饰如何影响活性的理解的空白。下一个资助期的研究将检验aPKC-?/？-介导的DNA结合域磷酸化通过以下途径调节Gli活性和Smo抑制剂耐药性：确定aPKC磷酸化如何影响Gli- DNA相互作用；3)确定耐药人类BCC肿瘤变异对BCC生长的功能影响。上述目标的完成将提供关键Gli转录因子所需的信息，并为帮助诊断和治疗单纯和耐药刺猬依赖性肿瘤提供见解。

DESCRIPTION (provided by applicant): Hedgehog (Hh) signaling has emerged as a key growth pathway in human carcinogenesis and inappropriate Hh target gene activation drives the growth of tumors such as skin basal cell carcinomas (BCCs). Experimental support from 5ARO54780 facilitated approval by the FDA of the first therapy aimed at the Smoothened (Smo) receptor. While na�ve tumors responded, resistance appears to be common, reiterating the need for developing new therapies targeting the Gli transcription factors downstream of Smo. 5ARO54780 in the prior funding period focused on factors that regulate Gli activity and showed the importance of the primary cilium and the basal body-associated Missing-in- Metastasis. Moreover, a proteomics screen to identify druggable components isolated the oncogenic polarity kinase aPKC-?/? and demonstrated that aPKC-?/? plays a key role in hedgehog signaling, BCC tumor growth, and Smo inhibitor resistance. In tumors, aPKC-?/? phosphorylates and activates Gli1 within the regulatory region of the DNA binding domain at residue Gli T304. By contrast, phosphorylation within the linker region of the DNA binding domain appears to inhibit function, revealing a gap in our understanding how DNA binding domain modifications affect activity. Studies in the next funding period will test the hypothesis that aPKC-?/?-mediated DNA binding domain phosphorylation regulates Gli activity and Smo inhibitor resistance by: Determining the consequences of Gli DNA binding domain phosphorylation; Determining how aPKC phosphorylation affects the Gli- DNA interaction; and by 3) Determining the functional consequences of resistant human BCC tumor variants on BCC growth. Completion of the above aims will provide needed information about the pivotal Gli transcription factor and provide insights to help diagnose and treat na�ve and resistant hedgehog-dependent tumors.