Cooperation of Hippo/Yap and Hedgehog Pathways in BCC Development

 描述（由申请方提供）：显著证据支持器官发生控制失败和致瘤过程重叠。事实上，祖细胞增殖和器官大小检查点的中心调节因子Hippo/雅普信号传导途径在各种人类肿瘤中经常过表达。在小鼠表皮中，雅普的过表达诱导滤泡间表皮（IFE）中祖细胞的扩增。人基底细胞癌（BCC）是一种皮肤肿瘤，起源于IFE祖细胞，是激活的Hedgehog信号传导的结果。Hedgehog和Hippo途径诱导IFE祖细胞增殖的能力表明这两种途径在致瘤过程中可以协同作用。事实上，Hippo/雅普通路被发现是刺猬驱动的髓母细胞瘤进展的重要介质。然而，BCC中Hippo和Hedgehog信号之间的相互作用完全不清楚。我们的初步实验表明，雅普被Hedgehog信号上调，并且是BCC发病机制所必需的。我们推测，在基底细胞癌的发生和发展过程中，Hippo和Hedgehog通路在皮肤基底干细胞中相互作用。以下具体目标将验证我们的假设：（1）确定Hippo/雅普通路在刺猬驱动的肿瘤中的需求;（2）研究雅普促进SmoM 2驱动的肿瘤发生的机制。 为了探究我们的第一个具体目标，我们将研究肿瘤起始或维持期间SmoM 2和Ptch诱导的BCC对雅普表达的体内依赖性。将对所得BCC肿瘤进行详细的肉眼和显微镜分析，以描述Hippo功能。将在多个时间点比较雅普熟练和Yap无效表皮的BCC克隆进化、增殖和凋亡。在具体目标2中，我们将研究雅普与TEAD转录因子的共激活功能，并在SmoM 2驱动的BCC中鉴定Yap调控的基因签名。使用具有针对每个通路的报告基因的细胞系，我们将确定Hedgehog-Hippo串扰的确切点。总之，我们的实验方法将研究BCC肿瘤对雅普表达的依赖性，并确定雅普在刺猬诱导的肿瘤发生过程中的机制作用。 人类基底细胞癌是最常见的肿瘤类型，发病率持续上升。晚期BCC肿瘤通常对Hedgehog通路拮抗剂具有耐药性，部分原因是其他通路协同支持进展。因此，鉴定相互作用的信号分子，加强刺猬驱动的BCC发病机制具有巨大的潜力，为未来的治疗干预。对Hippo和Hedgehog通路相互作用的更全面理解将揭示新的和生物学相关的治疗靶点。

 DESCRIPTION (provided by applicant): Significant evidence supports overlap of failed organogenesis control and tumorigenic process. Indeed, a central regulator of progenitor cell proliferation and organ size checkpoint, the Hippo/YAP signaling pathway, is frequently overexpressed in variety of human tumors. In the mouse epidermis, overexpression of Yap induces expansion of progenitor cells in the interfollicular epidermis (IFE). Human basal cell carcinoma (BCC) is a skin tumor originating from the IFE progenitor cells as a result of activated Hedgehog signaling. The capacity of the Hedgehog and Hippo pathways to induce proliferation of the IFE progenitor cells suggests that these two pathways could cooperate during a tumorigenic process. Indeed, The Hippo/Yap pathway was found to be an essential mediator of the Hedgehog-driven medulloblastoma progression. Nevertheless, interaction between the Hippo and Hedgehog signaling in BCC is completely unclear. Our preliminary experiments show that Yap is upregulated by active Hedgehog signaling and required for BCC pathogenesis. We hypothesize that the Hippo and Hedgehog pathways interact in the skin basal stem cell during BCC initiation and progression. Following specific aims will test our hypothesis: (1) To determine requirement of Hippo/YAP pathway in the Hedgehog-driven tumor; (2) to investigate a mechanism by which YAP promotes SmoM2-driven tumorigenesis. To interrogate our first specific aim, we will study in vivo dependence of SmoM2 and Ptch-induced BCC on Yap expression during tumor initiation or maintenance. Detailed macroscopic and microscopic analyses will be performed in resulting BCC tumors to delineate Hippo functions. The Yap proficient and Yap-null epidermis will be compared at multiple time points for BCC clonal evolution, proliferation, and apoptosis. In the specific aim 2, we will investigate Yap co-activato function with TEAD transcription factors and identify Yap-regulated gene signature in the SmoM2-driven BCC. Using cell lines with a reporter for each pathway, we will determine exact point of Hedgehog-Hippo crosstalk. Overall, our experimental approach will investigate dependence of BCC tumors on Yap expression and define a mechanistic role of Yap during the Hedgehog-induced tumorigenesis. Human BCC is the most common tumor type with continued increase in the incidence. The advanced BCC tumors are commonly resistant to the Hedgehog pathway antagonists in part due to cooperation of other pathways to support progression. Thus identification of interacting signaling molecules that potentiate Hedgehog-driven BCC pathogenesis has an enormous potential for the future of therapeutic intervention. A more comprehensive understanding of the Hippo and Hedgehog pathway interaction will uncover novel and biologically relevant therapeutic targets.