Radiation Induced Metabolic Alterations Associate With Tumor Aggressiveness and Poor Outcome in Glioblastoma
Radiation Induced Metabolic Alterations Associate With Tumor Aggressiveness and Poor Outcome in Glioblastoma
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DOI：
10.3389/fonc.2020.00535
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发表时间：
2020-05-05
影响因子：
4.7
通讯作者：
Burns, Terry C.
中科院分区：
文献类型：
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作者：
Gupta, Kshama;Vuckovic, Ivan;Burns, Terry C.
胶质母细胞瘤（GBM）是一致致命的，中位生存期为1年，尽管最好的治疗，包括放疗（RT）。既往放疗对肿瘤复发的影响尚不清楚，但可能增加肿瘤的侵袭性。代谢的变化已在辐射诱导的脑损伤进行了研究，然而，肿瘤促进作用后，事先辐射是缺乏的。由于RT对GBM管理至关重要，我们量化了既往RT对患者来源的颅内GBM异种移植物的促肿瘤作用，并表征了与促肿瘤微环境相关的代谢改变。与假手术动物相比，在20戈伊颅辐射后24小时将人异种移植物（GBM 143）植入裸鼠中。预辐射小鼠的肿瘤更具增殖性和浸润性，导致更快的死亡率（p < 0.0001）。肿瘤相关巨噬细胞/小胶质细胞（TAM）的组织学评价显示，在预辐射动物中，细胞具有更充分活化的阿米巴样形态。通过无监督液相色谱-质谱法（LC-MS）分析植入部位对侧肿瘤浸润边缘的放射性脑微透析液。在辐射前的动物中，已知与肿瘤进展相关的代谢物（即，修饰的核苷酸和多元醇）。使用H-1-NMR在单独的裸小鼠队列中对辐射前脑微环境的代谢改变进行全组织代谢组学分析，结果显示抗氧化剂（谷胱甘肽（GSH）和抗坏血酸盐（ASC））、NAD（+）、三羧酸循环（TCA）中间体水平显著降低，能量载体（ATP、GTP）水平升高。GSH和ASC在正交偏最小二乘判别分析（OPLS-DA）中显示出最高的投影预测变量重要性（VIPpred）（1.65）;通过GC-MS鉴定出抗坏血酸钙。为了评估辐射效应的寿命，我们比较了植入2个月与辐射后24小时的存活率，发现植入2个月的动物存活率更差。这些辐射诱导的变化与慢性疾病样微环境一致，其特征在于抗氧化剂和NAD（+）水平降低，细胞外ATP和GTP升高（作为化学引诱剂），促进细胞运动和囊泡分泌，GSH和ASC水平降低，加剧氧化应激。总之，这些数据表明IR诱导微环境中的肿瘤容许性变化，代谢组学改变可能促进肿瘤侵袭性，对复发性胶质母细胞瘤具有重要意义。利用这些代谢组学的见解可能会提供机会，以削弱复发性GBM的RT相关的侵略性。
Glioblastoma (GBM) is uniformly fatal with a 1-year median survival, despite best available treatment, including radiotherapy (RT). Impacts of prior RT on tumor recurrence are poorly understood but may increase tumor aggressiveness. Metabolic changes have been investigated in radiation-induced brain injury; however, the tumor-promoting effect following prior radiation is lacking. Since RT is vital to GBM management, we quantified tumor-promoting effects of prior RT on patient-derived intracranial GBM xenografts and characterized metabolic alterations associated with the protumorigenic microenvironment. Human xenografts (GBM143) were implanted into nude mice 24 hrs following 20 Gy cranial radiation vs. sham animals. Tumors in pre-radiated mice were more proliferative and more infiltrative, yielding faster mortality (p < 0.0001). Histologic evaluation of tumor associated macrophage/microglia (TAMs) revealed cells with a more fully activated ameboid morphology in pre-radiated animals. Microdialyzates from radiated brain at the margin of tumor infiltration contralateral to the site of implantation were analyzed by unsupervised liquid chromatography-mass spectrometry (LC-MS). In pre-radiated animals, metabolites known to be associated with tumor progression (i.e., modified nucleotides and polyols) were identified. Whole-tissue metabolomic analysis of pre-radiated brain microenvironment for metabolic alterations in a separate cohort of nude mice using H-1-NMR revealed a significant decrease in levels of antioxidants (glutathione (GSH) and ascorbate (ASC)), NAD(+), Tricarboxylic acid cycle (TCA) intermediates, and rise in energy carriers (ATP, GTP). GSH and ASC showed highest Variable Importance on Projection prediction (VIPpred) (1.65) in Orthogonal Partial least square Discriminant Analysis (OPLS-DA); Ascorbate catabolism was identified by GC-MS. To assess longevity of radiation effects, we compared survival with implantation occurring 2 months vs. 24 hrs following radiation, finding worse survival in animals implanted at 2 months. These radiation-induced alterations are consistent with a chronic disease-like microenvironment characterized by reduced levels of antioxidants and NAD(+), and elevated extracellular ATP and GTP serving as chemoattractants, promoting cell motility and vesicular secretion with decreased levels of GSH and ASC exacerbating oxidative stress. Taken together, these data suggest IR induces tumor-permissive changes in the microenvironment with metabolomic alterations that may facilitate tumor aggressiveness with important implications for recurrent glioblastoma. Harnessing these metabolomic insights may provide opportunities to attenuate RT-associated aggressiveness of recurrent GBM.