Elucidating the Role of PI3K Lipid Effectors in BRAF Mutant Melanoma

项目摘要 转移性黑色素瘤占皮肤癌死亡人数最多，目前， 只有15-20%的五年存活率这突出了对新疗法的迫切需求 来治疗这种复杂的疾病PI 3 K/AKT通路和RAS-RAF-MEK-ERK通路在细胞凋亡中起主要作用。 黑色素瘤的发生和发展。BRAF突变在大约50%的人类黑色素瘤中发现， 虽然在BRAF突变型黑色素瘤的发展中取得了显著的成功，但大多数 患者将经历原发性或继发性抵抗。此外，突变BRAF已被证明是 对于黑色素瘤的发生是不够的，然而突变激活的BRAF的机制与 癌基因和肿瘤抑制因子的缺失促进黑色素瘤的发生和发展并不理想 明白PI 3 K/AKT信号转导失调经常与BRAF突变同时观察到。 尽管AKT药理学抑制剂在临床试验中基本上无效， 剂.我们实验室的研究表明，药理学抑制和 AKT的遗传靶向，这表明对这种蛋白激酶的治疗性抑制不足以阻断其表达。 黑色素瘤中的活性。我们已经表明，基因敲低所有三个AKT旁系同源物导致完整的细胞凋亡， 在多种人黑色素瘤细胞系中具有致死性，并且每种AKT蛋白的过表达都能够 依赖于功能性激酶活性，显著地挽救这种有害作用。基于这些初步 结果，我们试图回答PI 3 K通路是否仅依赖于AKT信号转导在黑色素瘤中的作用 启动和进展。此外，迄今为止，我们还鉴定了另外的下游PI 3 K脂质， 结合蛋白，可以补偿这种疾病中AKT信号传导轴的抑制。我们 假设当AKT被抑制时，有其他PI 3 K脂质效应物，即SGK，与 AKT，其足以用于导致黑素瘤形成、进展和转移的下游信号传导。 这些脂质效应物的验证可能导致额外的治疗靶点。目前，该领域缺乏 更有效靶向BRAF有效合理组合MAPK和PI 3 K通路靶向治疗剂 突变的黑色素瘤，我们的目标是揭示并发激活的分子机制， 这些重要的信号通路。研究积累的结果将导致进一步的发现， 将改善黑色素瘤患者的健康状况，包括延长诊断后的平均寿命。

PROJECT ABSTRACT Metastatic melanoma accounts for the highest number of skin cancer deaths, and stage IV melanoma currently has only a devastating 15-20% five-year survival rate. This highlights the critical need for new therapeutics to treat this complex disease. The PI3K/AKT pathway and RAS-RAF-MEK-ERK pathway play a major role in melanoma initiation and progression. Mutations in BRAF are found in around 50% of all human melanomas, and although there has been significant success in the development of BRAF mutant melanomas, most patients will experience primary or secondary resistance. Furthermore, mutant BRAF has been shown to be insufficient for melanomagenesis, yet the mechanism by mutationally activated BRAF cooperates with oncogenes and loss of tumor suppressors to promote melanoma tumorigenesis and progression is not well understood. Dysregulated PI3K/AKT signaling is frequently observed concurrently with BRAF mutant melanomas though AKT pharmacological inhibitors have been largely ineffective in clinical trials as single agents. Studies in our lab have shown that there is a discordant effect between pharmacological inhibition and genetic targeting of AKT, suggesting that therapeutic inhibition of this protein kinase is insufficient to block its activity in melanoma. We have shown that genetic knockdown of all three AKT paralogs leads to complete cell lethality in multiple human melanoma cell lines, and overexpression of each of the AKT proteins is able to significantly rescue this deleterious effect, dependent on functional kinase activity. Based on these preliminary results, we seek to answer if the PI3K pathway depends solely on AKT signaling for its role in melanoma initiation and progression. Furthermore, to date, we have also identified additional downstream PI3K lipid binding proteins that may compensate for the inhibition of the AKT signaling axis in this disease. We hypothesize that when AKT is inhibited, there are other PI3K lipid effectors, namely SGK, highly homologous to AKT, that are sufficient for downstream signaling leading to melanoma formation, progression, and metastasis. The validation of these lipid effectors may lead to additional therapeutic targets. Currently, the field lacks effective rational combination MAPK and PI3K pathway-targeted therapeutics to more effectively target BRAF mutated melanomas, and our objective is to uncover the molecular mechanisms of the concurrent activation of these crucial signaling pathways. Results accumulated from the study will lead to further findings that in turn will improve the health of melanoma patients, including expanding the average life span after diagnosis.