Department of Molecular Biology of Cancer, Medical University of Lodz, 6/8 Mazowiecka Street, 92-215, Lodz, Poland.
Apoptosis. 2019 Aug;24(7-8):596-611. doi: 10.1007/s10495-019-01542-y.
Outcomes of melanoma patient treatment remain unsatisfactory despite accessibility of oncoprotein-targeting drugs and immunotherapy. Here, we reported that 17-aminogeldanamycin more potently activated caspase-3/7 in BRAF melanoma cells than geldanamycin, another inhibitor of heat shock protein 90 (HSP90). 17-aminogeldanamycin alleviated self-triggered compensatory increase in HSP70 mRNA level and induced endoplasmic reticulum (ER) stress, which was followed by selective diminution of cytoprotective IRE1α-XBP1s pathway activity of unfolded protein response (UPR), inhibition of ERK1/2 activity and induction of apoptosis. Concomitantly, ATF6/p50 level and expression of PERK-dependent genes, CHOP and BIM, remained unaltered. This might result from an inframe deletion in EIF2AK3 leading to a PERK variant revealed by whole-exome sequencing in melanoma cell lines. 17-aminogeldanamycin exhibited similar activity in NRAS melanoma cells that harbored a heterozygous inactivating variant of NAD(P)H:quinone oxidoreductase 1 (NQO1). In addition, 17-aminogeldanamycin acted cooperatively with trametinib (an inhibitor of MEK1/2) and vemurafenib (an inhibitor of BRAF) in induction of apoptosis in melanoma cell lines as evidenced by in-cell caspase-3/7 activation and PARP cleavage that occurred earlier compared with either drug used alone. As trametinib and vemurafenib did not significantly affect HSP70 and GRP78 transcript levels, cooperation of MEK/BRAF inhibitors and 17-aminogeldanamycin might result from a concurrent inhibition of the RAS/RAF/MEK/ERK cascade and IRE1α-dependent signaling, and cell-intrinsic ER homeostasis can determine the extent of the drug cooperation. Our study indicates that 17-aminogeldanamycin takes several advantages compared with other HSP90-targeting compounds, and can complement activity of BRAF/MEK inhibitors in melanoma cells of different genetic subtypes.
尽管可获得癌蛋白靶向药物和免疫疗法，黑色素瘤患者的治疗效果仍然不尽如人意。在这里，我们报道 17-氨基格尔德霉素比另一种热休克蛋白 90（HSP90）抑制剂格尔德霉素更有效地激活 BRAF 黑色素瘤细胞中的 caspase-3/7。17-氨基格尔德霉素减轻了 HSP70 mRNA 水平的自我触发补偿性增加，并诱导内质网（ER）应激，随后选择性地减少未折叠蛋白反应（UPR）中细胞保护的IRE1α-XBP1s 途径活性，抑制 ERK1/2 活性并诱导细胞凋亡。同时，ATF6/p50 水平和 PERK 依赖性基因 CHOP 和 BIM 的表达保持不变。这可能是由于黑色素瘤细胞系中的外显子组测序中发现 EIF2AK3 中的框内缺失导致 PERK 变体所致。17-氨基格尔德霉素在NRAS 黑色素瘤细胞中也表现出类似的活性，这些细胞携带 NAD（P）H：醌氧化还原酶 1（NQO1）的杂合失活变体。此外，17-氨基格尔德霉素与 trametinib（MEK1/2 抑制剂）和 vemurafenib（BRAF 抑制剂）协同作用，诱导黑色素瘤细胞系中的细胞凋亡，如细胞内 caspase-3/7 活化和 PARP 裂解所示，与单独使用任一药物相比更早发生。由于 trametinib 和 vemurafenib 对 HSP70 和 GRP78 转录物水平没有显著影响，MEK/BRAF 抑制剂和 17-氨基格尔德霉素的协同作用可能是由于 RAS/RAF/MEK/ERK 级联和 IRE1α 依赖性信号的同时抑制，以及细胞内 ER 稳态可以决定药物协同作用的程度。我们的研究表明，17-氨基格尔德霉素与其他 HSP90 靶向化合物相比具有多个优势，并且可以补充不同遗传亚型黑色素瘤细胞中 BRAF/MEK 抑制剂的活性。
