Regulating Gli Function in Hair Follicle Progenitors

描述(申请人提供)：Hhedgehog(HH)信号已成为人类致癌过程中的关键生长途径，不适当的HH靶基因激活会导致肿瘤的生长，如皮肤基底细胞癌(BCC)。来自5ARO54780的实验支持促进了FDA批准针对Smoothed(Smo)受体的第一种疗法。虽然幼稚的肿瘤有反应，但耐药性似乎很常见，重申了开发针对Smo下游的Gli转录因子的新疗法的必要性。5ARO54780在之前的筹资期间，重点关注调节Gli活性的因素，并显示了初级纤毛和与基底体相关的转移缺失的重要性。此外，蛋白质组学筛选分离出致癌极性激酶APKC-ι/λ，并证明APKC-ι/λ在Hedgehog信号、BCC肿瘤生长和SMO抑制剂耐药中发挥关键作用。在肿瘤中，APKC-ι/λ在GliT304残基的DNA结合结构域的调节区内磷酸化并激活Gli1。相比之下，DNA结合域连接区内的磷酸化似乎抑制了功能，这揭示了我们对DNA结合域修饰如何影响活性的理解上的差距。下一个资助期的研究将检验这一假设，即a PKC-ι/λ介导的DNA结合结构域磷酸化通过以下方式调节Gli活性和Smo抑制剂耐药性：确定Gli DNA结合结构域磷酸化的后果；确定a PKC磷酸化如何影响Gli-DNA相互作用；以及3)通过确定耐药人基底细胞癌肿瘤变异株对基底细胞癌生长的功能后果。上述目标的完成将提供关于关键的Gli转录因子的必要信息，并为帮助诊断和治疗幼稚和耐药的刺猬依赖型肿瘤提供见解。

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 naïve 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-ι/λ and demonstrated that aPKC-ι/λ plays a key role in hedgehog signaling, BCC tumor growth, and Smo inhibitor resistance. In tumors, aPKC-ι/λ 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-ι/λ-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 naïve and resistant hedgehog-dependent tumors.