El-Tohamy Rana, Elkholi Islam, Elsherbiny Marwa E, Magdy Mona, Hammam Olfat, Allalunis-Turner Joan, Emara Marwan
Center for Aging and Associated Diseases, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza 12578, Egypt.
Department of Pharmacology and Toxicology, Ahram Canadian University, 6th of October City, Giza 12566, Egypt.
Oncol Rep. 2020 Mar;43(3):975-985. doi: 10.3892/or.2020.7479. Epub 2020 Jan 23.
Glioblastoma multiforme (GBM) is the most aggressive human brain cancer. Little is known regarding how these cells adapt to the harsh tumor microenvironment, and consequently survive and resist various treatments. Myoglobin (MB), the oxygen‑binding hemoprotein, has been shown to be ectopically expressed in different human cancers and cell lines, and its expression is hypothesized to be an adaptation mechanism to hypoxia. The aim of the present study was to determine whether cancer‑related and hypoxia‑responsive MB mRNA splice variants are expressed in human GBM cells and glioblastoma tumor xenografts, and whether their expression is induced by hypoxia and correlated with hypoxia markers [lactate dehydrogenase A (LDHA), glucose transporter 1 (GLUT1), vascular endothelial growth factor (VEGF) and carbonic anhydrase IX (CAIX)]. Conventional reverse transcription (RT)‑PCR, DNA sequencing, RT‑quantitative PCR and immunohistochemistry were conducted to investigate MB expression in hypoxia‑sensitive (M010b, M059J) and ‑tolerant (M059K, M006xLo) GBM cell lines that also exhibit differential response towards radiation, rendering them a valuable translational GBM model. It was revealed that cancer‑related MB variants 9, 10, 11 and 13 were expressed in GBM cells under normoxia, and following hypoxia, their expression exhibited modest‑to‑significant upregulation that correlated with hypoxia markers. It was also demonstrated that MB was upregulated in hypoxic microregions of glioblastoma tumor xenografts that were stained in matched tumor regions of serial tumor sections with the hypoxia markers, pimonidazole, CAIX, VEGF and LDHA. The present study identified myoglobin as a potential contributor to the hypoxia adaptation and survival strategies of glioblastoma, and may explain the aggressiveness and frequent recurrence rates associated with GBM.
多形性胶质母细胞瘤（GBM）是最具侵袭性的人类脑癌。关于这些细胞如何适应恶劣的肿瘤微环境并因此存活下来并抵抗各种治疗方法，我们所知甚少。肌红蛋白（MB）是一种与氧结合的血红蛋白，已被证明在不同的人类癌症和细胞系中异位表达，并且据推测其表达是一种对缺氧的适应机制。本研究的目的是确定与癌症相关的和缺氧反应性的MB mRNA剪接变体是否在人GBM细胞和胶质母细胞瘤肿瘤异种移植物中表达，以及它们的表达是否由缺氧诱导并与缺氧标志物[乳酸脱氢酶A（LDHA）、葡萄糖转运蛋白1（GLUT1）、血管内皮生长因子（VEGF）和碳酸酐酶IX（CAIX）]相关。进行了常规逆转录（RT）-PCR、DNA测序、RT-定量PCR和免疫组织化学，以研究对缺氧敏感（M010b、M059J）和耐受（M059K、M006xLo）的GBM细胞系中的MB表达，这些细胞系对辐射也表现出不同的反应，使其成为一个有价值的转化GBM模型。结果显示，与癌症相关的MB变体9、10、11和13在常氧条件下的GBM细胞中表达，在缺氧后，它们的表达呈现出适度到显著的上调，且与缺氧标志物相关。还证明在胶质母细胞瘤肿瘤异种移植物的缺氧微区域中MB上调，这些区域在连续肿瘤切片的匹配肿瘤区域中用缺氧标志物匹莫硝唑、CAIX、VEGF和LDHA进行染色。本研究确定肌红蛋白是胶质母细胞瘤缺氧适应和生存策略的潜在贡献因素，并可能解释与GBM相关的侵袭性和高复发率。
