Zhao Yinu, Wang Weibin, Min Irene, Wyrwas Brian, Moore Maureen, Zarnegar Rasa, Fahey Thomas J
Department of Ophthalmology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, China.
Department of Surgery, New York Presbyterian Hospital and Weill Medical College of Cornell University, New York, NY, 10021, USA.
J Cancer Res Clin Oncol. 2017 Mar;143(3):447-455. doi: 10.1007/s00432-016-2317-y. Epub 2016 Dec 7.
Autophagy can function in a dual role in cancer development and progression: It can be cytoprotective or contribute to cell death. Therefore, determining the contextual role of autophagy between these two opposing effects is important. So far, little is known about the role of autophagy in uveal melanoma. In the present study, we looked to investigate the autophagic process, as well as its effect on cell survival in uveal melanoma cell lines under stressed conditions (starvation). The possible role of autophagy during BRAF inhibition in uveal melanoma was also sought.
Two human uveal melanoma cell lines, OCM1A, which harbors the BRAF mutation V600E and Mel 290, which is BRAF wild type, were studied. Autophagy levels were determined by Western blot assay with/without the addition of autophagic flux inhibitor (bafilomycin A1). Cell proliferation was assessed by an MTT assay.
Starvation triggered autophagy in BRAF V600E-mutant OCM1A cells but not in BRAF wild-type Mel 290 cells. Enhanced autophagy helped the OCM1A cells survive under stressed conditions. The BRAF inhibitor vemurafenib upregulated autophagy through suppression of the PI3K/Akt/mTOR/p70S6 K pathway in BRAF V600E-mutant uveal melanoma cells. Autophagy inhibition impaired the treatment efficacy of vemurafenib in BRAF V600E-mutant uveal melanoma cells.
Our data demonstrate that starvation-trigged autophagy, which is BRAF V600E dependent, promotes cancer cell survival in uveal melanoma. Vemurafenib induces autophagic cell death rather than adaptive cell survival in BRAF V600E-mutant melanoma.
自噬在癌症发展和进展中具有双重作用：它可以起到细胞保护作用，也可能导致细胞死亡。因此，确定自噬在这两种相反作用之间的具体作用很重要。到目前为止，关于自噬在葡萄膜黑色素瘤中的作用知之甚少。在本研究中，我们旨在研究在应激条件（饥饿）下葡萄膜黑色素瘤细胞系中的自噬过程及其对细胞存活的影响。我们还探索了自噬在葡萄膜黑色素瘤中BRAF抑制过程中的可能作用。
研究了两个人类葡萄膜黑色素瘤细胞系，携带BRAF突变V600E的OCM1A和BRAF野生型的Mel 290。通过添加或不添加自噬通量抑制剂（巴弗洛霉素A1）的蛋白质免疫印迹分析来确定自噬水平。通过MTT分析评估细胞增殖。
饥饿在BRAF V600E突变的OCM1A细胞中引发自噬，但在BRAF野生型Mel 290细胞中未引发。增强的自噬有助于OCM1A细胞在应激条件下存活。BRAF抑制剂维莫非尼通过抑制BRAF V600E突变的葡萄膜黑色素瘤细胞中的PI3K/Akt/mTOR/p70S6K途径上调自噬。自噬抑制削弱了维莫非尼对BRAF V600E突变的葡萄膜黑色素瘤细胞的治疗效果。
我们的数据表明，饥饿引发的、依赖BRAF V600E的自噬促进了葡萄膜黑色素瘤中的癌细胞存活。维莫非尼在BRAF V600E突变的黑色素瘤中诱导自噬性细胞死亡而非适应性细胞存活。
