Sa-Nongdej Wanna, Chongthammakun Sukumal, Songthaveesin Chanchai
Ramathibodi School of Nursing, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, 10400, Thailand.
Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
Heliyon. 2021 Feb 26;7(2):e06352. doi: 10.1016/j.heliyon.2021.e06352. eCollection 2021 Feb.
Glioblastoma is a severe cancer with extremely poor survival. Its treatment typically involves a combination of surgery, chemotherapy, and radiation therapy. However, glioma stem-like cells (GSCs)-a subpopulation of tumor-propagating glioblastoma cells-cause post-treatment recurrence and are a major factor in the poor prognosis of the disease. GSCs have higher proliferation than non-GSCs and are more resistant to invasive chemotherapy and radiotherapy. In this study, we subjected GSCs to nutrient starvation (deprived of glucose, glutamine, and calcium) to determine whether cell death can be triggered as a potential strategy to improve treatment outcomes. Flow cytometry revealed that 35.1%, 96.1%, and 99.9% of starved GSCs underwent apoptosis on days 1, 3, and 5, respectively, along with nearly 100% autophagy on all three days. Western blots detected cleaved caspase-3 (an apoptosis marker) and phospho-beclin 1, LC 3B-I, LC 3B-II (autophagy markers) in C6 GSCs after nutrient starvation for 1, 3, 4, and 5 days. Transmission electron microscopic observation of GSC ultrastructure after starvation treatment revealed that compared with control GSCs, starved cells had more pyknotic nuclei, membrane bleb, swollen endoplasmic reticulum, degenerative mitochondria, lipid droplets, and microvilli loss. Thus, nutrient starvation stresses cells by increasing free radicals. Cell stress opens more channels between mitochondria and endoplasmic reticulum. This study demonstrated that nutrient starvation decreases proliferation by approximately 81%, while increasing apoptosis (99.9%) and autophagy (94.6%) in C6 GSCs by the fifth day. Nutrient starvation of GSCs may, therefore, be an effective therapeutic strategy that can trigger apoptotic and autophagic metabolic reprogramming in cancer cells.
胶质母细胞瘤是一种严重的癌症，生存率极低。其治疗通常包括手术、化疗和放射治疗的联合应用。然而，胶质瘤干细胞（GSCs）——肿瘤增殖性胶质母细胞瘤细胞的一个亚群——会导致治疗后复发，并且是该疾病预后不良的主要因素。GSCs比非GSCs具有更高的增殖能力，并且对侵入性化疗和放疗更具抗性。在本研究中，我们使GSCs处于营养饥饿状态（缺乏葡萄糖、谷氨酰胺和钙）以确定是否可以触发细胞死亡，作为改善治疗结果的潜在策略。流式细胞术显示，饥饿的GSCs在第1天、第3天和第5天分别有35.1%、96.1%和99.9%发生凋亡，并且在这三天中几乎100%发生自噬。蛋白质免疫印迹法检测到营养饥饿1天、3天、4天和5天后，C6 GSCs中存在裂解的半胱天冬酶-3（一种凋亡标志物）以及磷酸化的贝林1、LC 3B-I、LC 3B-II（自噬标志物）。饥饿处理后对GSC超微结构的透射电子显微镜观察显示，与对照GSCs相比，饥饿细胞有更多固缩核、膜泡、内质网肿胀、线粒体退化、脂滴以及微绒毛缺失。因此，营养饥饿通过增加自由基来使细胞产生应激。细胞应激会在内质网和线粒体之间打开更多通道。本研究表明，营养饥饿使C6 GSCs的增殖在第5天时降低约81%，同时使凋亡（99.9%）和自噬（94.6%）增加。因此，GSCs的营养饥饿可能是一种有效的治疗策略，可触发癌细胞的凋亡和自噬性代谢重编程。
