Critical roles for nitric oxide and ERK in the completion of prosurvival autophagy in 4OHTAM-treated estrogen receptor-positive breast cancer cells.
Critical roles for nitric oxide and ERK in the completion of prosurvival autophagy in 4OHTAM-treated estrogen receptor-positive breast cancer cells.
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DOI：
10.1016/j.canlet.2014.07.031
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发表时间：
2014-10-28
期刊：
影响因子：
9.7
通讯作者：
Maki CG
中科院分区：
文献类型：
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作者：
Duan L;Danzer B;Levenson VV;Maki CG
自噬是ER阳性（ER+）乳腺癌细胞对他莫昔芬（TAM）耐药的一种机制。在这项研究中，我们在ER+ MCF 7细胞中发现，4-羟基他莫昔芬（4 OHTAM）诱导细胞一氧化氮（NO），负调节细胞超氧化物（O2−）和细胞毒性。4 OHTAM刺激LC 3脂质化和形成依赖于O2−的单丹酰尸胺（MDC）标记的自噬囊泡。NO的消耗增加了O2−和LC 3的脂化，但减少了MDC标记的自噬囊泡的形成。相反，NO耗尽的细胞形成非常大的空泡与边缘装饰LC 3。空泡未被MDC或酸性溶酶体特异性荧光染料吖啶橙子（AO）标记。晚期自噬抑制剂氯喹增加了空泡，这也增加了LC 3脂化。这些结果表明，NO是必要的适当的自噬囊泡形成或成熟后的步骤LC 3脂化。此外，4 OHTAM诱导ERK的O2-依赖性激活，4 OHTAM处理后抑制ERK使溶酶体/自溶酶体不稳定，并与NO耗尽一起导致坏死性细胞死亡。这些结果表明内源性NO和ERK激活在促生存自噬的完成中起重要作用。
Autophagy is a mechanism of tamoxifen (TAM) resistance in ER-positive (ER+) breast cancer cells. In this study, we showed in ER+ MCF7 cells that 4-hydroxytamoxifen (4OHTAM) induced cellular nitric oxide (NO) that negatively regulates cellular superoxide (O2−) and cytotoxicity. 4OHTAM stimulated LC3 lipidation and formation of monodansylcadaverine (MDC)-labeled autophagic vesicles dependent on O2−. Depletion of NO increased O2− and LC3 lipidation, yet reduced formation of MDC-labeled autophagic vesicles. Instead, NO-depleted cells formed remarkably large vacuoles with rims decorated by LC3. The vacuoles were not labeled by MDC or the acidic lysosome-specific fluorescence dye acridine orange (AO). The vacuoles were increased by the late stage autophagy inhibitor chloroquine, which also increased LC3 lipidation. These results suggest NO is required for proper autophagic vesicle formation or maturation at a step after LC3 lipidation. In addition, 4OHTAM induced O2−-dependent activation of ERK, inhibition of which destabilized lysosomes/autolysosomes upon 4OHTAM treatment and together with depletion of NO led to necrotic cell death. These results suggest an essential role for endogenous NO and ERK activation in the completion of pro-survival autophagy.