Department of Oncological Sciences, University of Utah, Salt Lake City, Utah.
Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
Clin Cancer Res. 2020 Dec 1;26(23):6374-6386. doi: 10.1158/1078-0432.CCR-20-1675. Epub 2020 Sep 15.
Mutational activation of or (), detected in >90% of uveal melanomas, leads to constitutive activation of oncogenic pathways, including MAPK and YAP. To date, chemo- or pathway-targeted therapies, either alone or in combination, have proven ineffective in the treatment of patients with metastatic uveal melanoma.
We tested the efficacy of chloroquine or hydroxychloroquine, in combination with MAPK pathway inhibition in -mutated cells and and identified mechanisms of MEK1/2 inhibitor plus chloroquine-induced cytotoxicity.
Inhibition of GNAQ/11-mediated activation of MAPK signaling resulted in the induction of autophagy. Combined inhibition of Gα and autophagy or lysosome function resulted in enhanced cell death. Moreover, the combination of MEK1/2 inhibition, using trametinib, with the lysosome inhibitor, chloroquine, also increased cytotoxicity. Treatment of mice bearing GNAQ/11-driven melanomas with trametinib plus hydroxychloroquine resulted in inhibition of tumor growth and significantly prolonged survival. Interestingly, lysosomal- and autophagy-specific inhibition with bafilomycin A1 was not sufficient to promote cytotoxicity in combination with trametinib. However, the addition of YAP inhibition with trametinib plus bafilomycin A1 resulted in cell death at comparable levels to trametinib plus chloroquine (T/CQ) treatment. Furthermore, T/CQ-treated cells displayed decreased YAP nuclear localization and decreased YAP transcriptional activity. Expression of a constitutively active YAP mutant conferred resistance to T/CQ-induced cell death.
These results suggest that YAP, MEK1/2, and lysosome function are necessary and critical targets for the therapy of GNAQ/11-driven melanoma, and identify trametinib plus hydroxychloroquine as a potential treatment strategy for metastatic uveal melanoma.
在超过 90%的葡萄膜黑色素瘤中检测到 或 （）的突变激活，导致致癌途径的组成性激活，包括 MAPK 和 YAP。迄今为止，化学疗法或靶向途径的治疗，无论是单独使用还是联合使用，在治疗转移性葡萄膜黑色素瘤患者方面都证明是无效的。
我们测试了氯喹或羟氯喹与 MAPK 途径抑制联合治疗 GNAQ/11 突变细胞 和 的疗效，并确定了 MEK1/2 抑制剂加氯喹诱导细胞毒性的机制。
抑制 GNAQ/11 介导的 MAPK 信号转导的激活导致自噬的诱导。Gα 联合抑制和自噬或溶酶体功能的抑制导致细胞死亡增加。此外，使用 trametinib 抑制 MEK1/2，与溶酶体抑制剂氯喹联合使用，也增加了细胞毒性。用 trametinib 加羟氯喹治疗携带 GNAQ/11 驱动的黑色素瘤的小鼠导致肿瘤生长抑制和生存时间显著延长。有趣的是，用 bafilomycin A1 进行溶酶体和自噬特异性抑制不足以与 trametinib 联合促进细胞毒性。然而，在用 trametinib 加 bafilomycin A1 抑制 YAP 的同时，与 trametinib 加氯喹（T/CQ）治疗相比，导致细胞死亡的水平相当。此外，T/CQ 处理的细胞显示出 YAP 核定位减少和 YAP 转录活性降低。组成性激活的 YAP 突变体的表达赋予了对 T/CQ 诱导的细胞死亡的抗性。
这些结果表明，YAP、MEK1/2 和溶酶体功能是治疗 GNAQ/11 驱动的黑色素瘤的必要和关键靶点，并确定 trametinib 加羟氯喹是治疗转移性葡萄膜黑色素瘤的潜在治疗策略。
