Skøyum R, Eide K, Berg K, Rofstad E K
Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, Oslo, Norway.
Br J Cancer. 1997;76(4):421-8. doi: 10.1038/bjc.1997.405.
The response to treatment and the malignant progression of tumours are influenced by the ability of the tumour cells to withstand severe energy deprivation during prolonged exposure to hypoxia at normal or low extracellular pH (pHe). The objective of the present work was to demonstrate intertumour heterogeneity under conditions of microenvironment-induced energy deprivation and to investigate whether the heterogeneity can be attributed to differences in the capacity of the tumour cells to generate energy in an oxygen-deficient microenvironment. Cultures of four human melanoma cell lines (BEX-c, COX-c, SAX-c, WIX-c) were exposed to hypoxia in vitro at pHe 7.4, 7.0 or 6.6 for times up to 31 h by using the steel-chamber method. High-performance liquid chromatography was used to assess adenylate energy charge as a function of exposure time. Cellular rates of glucose uptake and lactate release were determined by using standard enzymatic test kits. The adenylate energy charge decreased with time under hypoxia in all cell lines. The decrease was most pronounced shortly after the treatment had been initiated and then tapered off. BEX-c and SAX-c showed a significantly higher adenylate energy charge under hypoxic conditions than did COX-c and WIX-c whether the pHe was 7.4, 7.0 or 6.6, showing that tumours can differ in the ability to avoid energy deprivation during microenvironmental stress. There was no correlation between the adenylate energy charge and the rates of glucose uptake and lactate release. Intertumour heterogeneity in the ability to withstand energy deprivation in an oxygen-deficient microenvironment cannot therefore be attributed mainly to differences in the capacity of the tumour cells to generate energy by anaerobic metabolism. The data presented here suggest that the heterogeneity is rather caused by differences in the capacity of the tumour cells to reduce the rate of energy consumption when exposed to hypoxia.
肿瘤细胞在正常或低细胞外pH值（pHe）下长时间暴露于缺氧环境时耐受严重能量剥夺的能力，会影响肿瘤的治疗反应和恶性进展。本研究的目的是证明在微环境诱导的能量剥夺条件下肿瘤间的异质性，并研究这种异质性是否可归因于肿瘤细胞在缺氧微环境中产生能量能力的差异。通过钢室法，将四种人黑色素瘤细胞系（BEX-c、COX-c、SAX-c、WIX-c）的培养物在体外分别于pHe 7.4、7.0或6.6的条件下暴露于缺氧环境长达31小时。采用高效液相色谱法评估腺苷酸能量电荷随暴露时间的变化。使用标准酶测试试剂盒测定细胞葡萄糖摄取率和乳酸释放率。在缺氧条件下，所有细胞系的腺苷酸能量电荷均随时间下降。下降在处理开始后不久最为明显，然后逐渐减缓。无论pHe为7.4、7.0还是6.6，BEX-c和SAX-c在缺氧条件下的腺苷酸能量电荷均显著高于COX-c和WIX-c，这表明肿瘤在微环境应激期间避免能量剥夺的能力可能存在差异。腺苷酸能量电荷与葡萄糖摄取率和乳酸释放率之间没有相关性。因此，缺氧微环境中耐受能量剥夺能力的肿瘤间异质性不能主要归因于肿瘤细胞通过无氧代谢产生能量能力的差异。此处呈现的数据表明，这种异质性更可能是由肿瘤细胞在暴露于缺氧环境时降低能量消耗速率的能力差异所导致的。
