PPP6C Regulation of ERK Signaling in Melanoma

项目总结/摘要 黑色素瘤是最致命的皮肤癌，其特征是ERK有丝分裂原的异常过度活化， 活化蛋白激酶（MAPK）信号通路。BRAF和MEK的抑制剂，这两个成员 已经显示出临床疗效，并联合用于治疗BRAF突变型黑色素瘤， 常见的黑色素瘤基因亚型。然而，并非所有BRAF突变型黑色素瘤都对这些抑制剂有反应， 而那些有反应的最终会产生抗药性。更好地理解分子机制 潜在的对BRAF和MEK抑制剂的反应和耐药性将使我们更接近于开发持久的 治疗策略该项目的主要目标是为PPP 6C建立一种新的调节作用， 蛋白磷酸酶6（PPP 6C）的催化亚基，在ERK信号网络。这将允许 了解PPP 6C中观察到的遗传病变如何改变这种致癌信号通路，可能会推动 恶性转化以及黑色素瘤的耐药性。我们对PPP 6C的兴趣基于1） 前期工作观察到PPP 6C的下调促进了对MEK抑制的抗性， ERK激活和2）全外显子组和靶向测序项目，鉴定PPP 6C在7-12%中突变 黑色素瘤该提案将研究PPP 6C沉默对ERK激活和抑制剂的影响。 一组黑色素瘤患者来源细胞的敏感性，以证实PPP 6C在调节ERK中的作用 发信号。将确定PPP 6C调节ERK信号传导的具体信号传导机制 通过细胞和生物化学方法研究PPP 6C如何直接或间接调节MEK activation.肿瘤相关PPP 6C对ERK信号转导和MEK/BRAF抑制剂敏感性的调节 将在培养的细胞和黑素瘤的小鼠模型中检查突变。为了评估致瘤性 PPP 6C丢失的可能性，将评价PPP 6C敲低黑素细胞的生长因子非依赖性 增殖和非贴壁生长。这些研究的结果将提供洞察如何 优化临床MEK和BRAF抑制剂在黑色素瘤中的使用，并确定改善 靶向治疗的有效性。

PROJECT SUMMARY/ABSTRACT Melanoma, the deadliest form of skin cancer, is characterized by aberrant hyperactivation of the ERK mitogen- activated protein kinase (MAPK) signaling pathway. Inhibitors of BRAF and MEK, both members of this pathway, have shown clinical efficacy and are used in combination to treat BRAF mutant melanoma, the most common melanoma genomic subtype. However, not all BRAF mutant melanomas respond to these inhibitors, and those that do respond eventually acquire resistance. Better understanding the molecular mechanisms underlying the response and resistance to BRAF and MEK inhibitors will bring us closer to developing durable therapeutic strategies. The main goal of this project is to establish a novel regulatory role for PPP6C, the catalytic subunit of protein phosphatase 6 (PPP6C), in the ERK signaling network. This will allow for understanding how observed genetic lesions in PPP6C alter this oncogenic signaling pathway, likely driving malignant transformation as well as drug resistance in melanoma. Our interest in PPP6C is based on 1) preliminary work observing downregulation of PPP6C promotes resistance to MEK inhibition and increases ERK activation and 2) whole exome and targeted sequencing projects identifying PPP6C is mutated in 7-12% of melanomas. This proposal will examine the effects of PPP6C silencing on ERK activation and inhibitor sensitivity across a panel of melanoma patient-derived cells to confirm a role for PPP6C in regulating ERK signaling. The specific signaling mechanisms underlying PPP6C regulation of ERK signaling will be determined by cellular and biochemical approaches investigating how PPP6C directly or indirectly regulates MEK activation. Regulation of ERK signaling and MEK/BRAF inhibitor susceptibility by cancer-associated PPP6C mutations will be examined in cultured cells and in a mouse model of melanoma. To assess the tumorigenic potential of PPP6C loss, PPP6C knockdown melanocytes will be evaluated for growth factor independent proliferation and anchorage independent growth. The findings from these studies will provide insight into how to optimize the use of clinical MEK and BRAF inhibitors in melanoma and identify opportunities to improve the efficacy of targeted therapies.