Maeda Masatomo, Ko Myat, Mane Mayuresh M, Cohen Ivan J, Shindo Masahiro, Vemuri Kiranmayi, Serganova Inna, Blasberg Ronald
Department of Neurology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
Cancers (Basel). 2022 May 6;14(9):2306. doi: 10.3390/cancers14092306.
The effects of the LDH-A depletion via shRNA knockdown on three murine glioma cell lines and corresponding intracranial (i.c.) tumors were studied and compared to pharmacologic (GNE-R-140) inhibition of the LDH enzyme complex, and to shRNA scrambled control (NC) cell lines. The effects of genetic-shRNA LDH-A knockdown and LDH drug-targeted inhibition (GNE-R-140) on tumor-cell metabolism, tumor growth, and animal survival were similar. LDH-A KD and GNE-R-140 unexpectedly increased the aggressiveness of GL261 intracranial gliomas, but not CT2A and ALTS1C1 i.c. gliomas. Furthermore, the bioenergetic profiles (ECAR and OCR) of GL261 NC and LDH-A KD cells under different nutrient limitations showed that (a) exogenous pyruvate is not a major carbon source for metabolism through the TCA cycle of native GL261 cells; and (b) the unique upregulation of LDH-B that occurs in GL261 LDH-A KD cells results in these cells being better able to: (i) metabolize lactate as a primary carbon source through the TCA cycle, (ii) be a net consumer of lactate, and (iii) showed a significant increase in the proliferation rate following the addition of 10 mM lactate to the glucose-free media (only seen in GL261 KD cells). Our study suggests that inhibition of LDH-A/glycolysis may not be a general strategy to inhibit the i.c. growth of all gliomas, since the level of LDH-A expression and its interplay with LDH-B can lead to complex metabolic interactions between tumor cells and their environment. Metabolic-inhibition treatment strategies need to be carefully assessed, since the inhibition of glycolysis (e.g., inhibition of LDH-A) may lead to the unexpected development and activation of alternative metabolic pathways (e.g., upregulation of lipid metabolism and fatty-acid oxidation pathways), resulting in enhanced tumor-cell survival in a nutrient-limited environment and leading to increased tumor aggressiveness.
通过短发夹RNA（shRNA）敲低来消耗乳酸脱氢酶A（LDH-A）对三种小鼠胶质瘤细胞系及相应的颅内肿瘤的影响进行了研究，并与药理学方法（GNE-R-140）抑制LDH酶复合物以及shRNA乱序对照（NC）细胞系进行了比较。基因敲低LDH-A的短发夹RNA（shRNA）和LDH药物靶向抑制（GNE-R-140）对肿瘤细胞代谢、肿瘤生长和动物存活的影响相似。LDH-A敲低（KD）和GNE-R-140意外地增加了GL261颅内胶质瘤的侵袭性，但对CT2A和ALTS1C1颅内胶质瘤没有影响。此外，不同营养限制条件下GL261 NC和LDH-A KD细胞的生物能量学特征（细胞外酸化率[ECAR]和氧消耗率[OCR]）表明：（a）外源性丙酮酸不是天然GL261细胞通过三羧酸循环进行代谢的主要碳源；（b）GL261 LDH-A KD细胞中发生的LDH-B独特上调使这些细胞更能够：（i）通过三羧酸循环将乳酸作为主要碳源进行代谢，（ii）成为乳酸的净消耗者，以及（iii）在无葡萄糖培养基中添加10 mM乳酸后增殖率显著增加（仅在GL261 KD细胞中观察到）。我们的研究表明，抑制LDH-A/糖酵解可能不是抑制所有胶质瘤颅内生长的通用策略，因为LDH-A的表达水平及其与LDH-B的相互作用可导致肿瘤细胞与其环境之间复杂的代谢相互作用。由于糖酵解的抑制（例如，抑制LDH-A）可能导致替代代谢途径的意外发展和激活（例如，脂质代谢和脂肪酸氧化途径的上调），从而在营养受限环境中提高肿瘤细胞的存活率并导致肿瘤侵袭性增加，因此需要仔细评估代谢抑制治疗策略。
