PAK Kinases Regulate Melanoma Chemoresistance and Metastasis

描述(申请人提供)：黑色素瘤肿瘤在发展的早期阶段转移，并且对化疗药物具有众所周知的抗药性。我们最近利用系统水平的RNAi筛选方法来揭示黑色素瘤化疗耐药的分子调节因素。这些研究确定，RhoJ及其下游的激酶PAK1抑制了黑色素瘤细胞中感觉到DNA损伤的通路。其他研究表明，RhoJ和PAK1还通过调节肌动蛋白细胞骨架动力学来调节黑色素瘤的侵袭。这些观察结果使我们假设PAK激酶磷酸化下游靶点，抑制DNA损伤感知并促进黑色素瘤转移。在这项建议中，我们确定了PAK1是如何抑制DNA损伤感知的，并确定了在体内PAK1是否抑制了DNA损伤感知。更多的研究将确定调节黑色素瘤细胞侵袭的PAK激酶靶点，并验证PAK激酶调节体内黑色素瘤转移。在该提案的最终目的中，我们将研究PAK激酶是否在预后不良/耐药的人类黑色素瘤中被选择性激活，并确定PAK抑制剂是否既能使小鼠黑色素瘤对化疗药物敏感，又能抑制小鼠黑色素瘤的转移。这些研究的完成将导致设计出更有效的PAK抑制剂，可用于治疗转移性黑色素瘤。

DESCRIPTION (provided by applicant): Melanoma tumors metastasize at an early stage of development and are notoriously resistant to chemotherapeutics. We recently utilized a systems-level RNAi screening approach to uncover the molecular regulators of melanoma chemoresistance. These studies determined that RhoJ and its downstream kinase PAK1 suppress pathways in melanoma cells that sense DNA damage. Additional studies revealed that RhoJ and PAK1 also regulate melanoma invasion by modulating actin cytoskeletal dynamics. These observations led us to hypothesize that PAK kinases phosphorylate downstream targets that suppress DNA damage sensing and promote melanoma metastasis. In this proposal, we determine how PAK1 suppresses DNA damage sensing and determine whether Pak1 suppresses DNA damage sensing in vivo. Additional studies will identify PAK kinase targets that modulate melanoma cell invasion and verify that PAK kinases regulate melanoma metastasis in vivo. In the final aim of the proposal, we will examine whether PAK kinases are selectively activated in poor prognosis/chemoresistant human melanomas and determine whether PAK inhibitors can both sensitize mouse melanomas to chemotherapeutics and inhibit murine melanoma metastasis. Completion of these studies will lead to the design of more effective PAK inhibitors that can be used to treat metastatic melanoma.