Sudsaward Sangkab, Khunchai Sasiprapa, Thepmalee Chutamas, Othman Aisha, Limjindaporn Thawornchai, Yenchitsomanus Pa-Thai, Mutti Luciano, Krstic-Demonacos Marija, Demonacos Constantinos
School of Science, Engineering and Environment, University of Salford, Salford, M5 4WT, UK.
Department of Anatomy, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand.
Int J Oncol. 2020 Sep;57(3):835-844. doi: 10.3892/ijo.2020.5089. Epub 2020 Jun 26.
Acute lymphoblastic leukaemia (ALL) is the most frequent childhood cancer and, although it is highly treatable, resistance to therapy, toxicity and side effects remain challenging. The synthetic glucocorticoid (GC) dexamethasone (Dex) is commonly used to treat ALL, the main drawback of which is the development of resistance to this treatment. The aim of the present study was to investigate potential molecular circuits mediating resistance and sensitivity to GC‑induced apoptosis in ALL. The leukaemia cell lines CEM‑C7‑14, CEM‑C1‑15 and MOLT4 treated with chloroquine (CLQ), thapsigargin (TG) and rotenone (ROT) were used to explore the roles of autophagy, endoplasmic reticulum (ER) stress/unfolded protein response (UPR) and reactive oxygen species (ROS) generation in the response to GC treatment. ROS levels were associated with increased cell death and mitochondrial membrane potential in rotenone‑treated CEM cells. Autophagy inhibition by CLQ exhibited the strongest cytotoxic effect in GC‑resistant leukaemia. Autophagy may act as a pro‑survival mechanism in GC‑resistant leukaemia since increasing trends in beclin‑1 and microtubule‑associated protein 1 light chain 3α levels were detected in CEM‑C1‑15 and MOLT4 cells treated with Dex, whereas decreasing trends in these autophagy markers were observed in CEM‑C7‑14 cells. The intracellular protein levels of the ER stress markers glucose‑regulated protein (GRP)78 and GRP94 were stimulated by Dex only in the GC‑sensitive cells, suggesting a role of these chaperones in the GC‑mediated ALL cell death. Increased cell surface levels of GRP94 were recorded in CEM‑C7‑14 cells treated with combination of Dex with TG compared with those in cells treated with TG alone, whereas decreasing trends were observed in CEM‑C1‑15 cells under these conditions. Taken together, the results of the present study demonstrated that autophagy may be a pro‑survival mechanism in GC‑resistant leukaemia, and by modulating intracellular and surface GRP94 protein levels, Dex is involved in the regulation of ER stress/UPR‑dependent cell death and immune surveillance. These observations may be of clinical importance if confirmed in patients.
急性淋巴细胞白血病（ALL）是儿童期最常见的癌症，尽管其治愈率很高，但治疗耐药性、毒性和副作用仍然是具有挑战性的问题。合成糖皮质激素（GC）地塞米松（Dex）常用于治疗ALL，其主要缺点是会产生对这种治疗的耐药性。本研究的目的是调查介导ALL中对GC诱导的细胞凋亡产生耐药性和敏感性的潜在分子通路。用氯喹（CLQ）、毒胡萝卜素（TG）和鱼藤酮（ROT）处理白血病细胞系CEM-C7-14、CEM-C1-15和MOLT4，以探讨自噬、内质网（ER）应激/未折叠蛋白反应（UPR）和活性氧（ROS）生成在对GC治疗反应中的作用。在鱼藤酮处理的CEM细胞中，ROS水平与细胞死亡增加和线粒体膜电位相关。CLQ抑制自噬在GC耐药白血病中表现出最强的细胞毒性作用。自噬可能在GC耐药白血病中作为一种促生存机制，因为在用Dex处理的CEM-C1-15和MOLT4细胞中检测到贝林1和微管相关蛋白1轻链3α水平呈上升趋势，而在CEM-C7-14细胞中观察到这些自噬标志物呈下降趋势。ER应激标志物葡萄糖调节蛋白（GRP）78和GRP94的细胞内蛋白水平仅在GC敏感细胞中受到Dex的刺激，表明这些伴侣蛋白在GC介导的ALL细胞死亡中起作用。与单独用TG处理的细胞相比，在用Dex与TG联合处理的CEM-C7-14细胞中记录到GRP94的细胞表面水平增加，而在这些条件下CEM-C1-15细胞中观察到下降趋势。综上所述，本研究结果表明自噬可能是GC耐药白血病中的一种促生存机制，并且通过调节细胞内和表面GRP94蛋白水平，Dex参与ER应激/UPR依赖性细胞死亡和免疫监视的调节。如果在患者中得到证实，这些观察结果可能具有临床意义。
