Breast cancer cells have a high capacity to acidify extracellular milieu by a dual mechanism
Breast cancer cells have a high capacity to acidify extracellular milieu by a dual mechanism
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DOI：
10.1023/a:1018446104071
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发表时间：
1997-07-01
影响因子：
4
通讯作者：
Rochefort, H
中科院分区：
文献类型：
--
作者：
Montcourrier, P;Silver, I;Rochefort, H
众所周知，恶性肿瘤的细胞外 pH 值低于正常组织，因此可能有利于分泌的溶酶体组织蛋白酶的细胞外激活。我们使用两种技术测试了人乳腺细胞（连续细胞系和原代培养物）酸化其细胞外环境的能力。通过改变苯酚砜酞吸光度来测量 pH 值变化，我们发现更具攻击性的 MDA-MB-231 人乳腺癌细胞在酸化细胞外环境方面更活跃。非缓冲平衡盐溶液比雌激素受体阳性MCF7和ZR75细胞系和原代培养的正常乳腺上皮细胞高。来自胸腔积液的转移性乳腺癌细胞在酸化其细胞外环境方面的活性比在相同条件下培养的非恶性乳腺细胞高 200 倍，强烈表明这种差异也发生在体内。在存在或不存在葡萄糖的情况下使用抑制剂表明，乳酸和 ATP 驱动的质子泵共享液泡 H+ 泵的一些特征，巴弗洛霉素 A1 是一种特异性抑制剂。液泡（V型）ATP-H+泵抑制MCF7细胞的部分酸化，但不抑制MDA-MB-231细胞的酸化。我们还使用微电极测量细胞外pH，与MCF7乳腺癌细胞紧密接触，MCF7细胞自由表面的pH比周围介质低0.33+/-0.14单位，而将微电极尖端插入细胞附着表面下方显示出更大的pH。只要细胞附着在基质上阻止 H+ 扩散，pH 从 0.3 降低到 1.7 pH 单位，我们得出结论，乳腺癌细胞比正常乳腺细胞具有更高的酸化细胞外环境的能力，并且质膜 H+-ATP 酶和乳酸产生都参与这种酸化。因此，肿瘤细胞过量分泌的天冬氨酰和半胱氨酰组织蛋白酶原可能在体内靠近基底膜的细胞外被激活。
The extracellular pH in malignant tumors is known to be lower than in normal tissues and may therefore facilitate extracellular activation of secreted lysosomal cathepsins, We have tested the capability of human mammary cells (continuous cell lines and primary culture) to acidify their extracellular environment, using two techniques, By measuring pH changes through alterations of phenolsulfone phthaleine absorbance, we found that the more aggressive MDA-MB-231 human breast cancer cells were more active in acidifying a non-buffered balanced salt solution than the estrogen receptor positive MCF7 and ZR75 cell lines and than normal mammary epithelial cells in primary culture. Metastatic breast cancer cells from pleural effusions were up to 200-fold more active in acidifying their extracellular milieu than non-malignant mammary cells cultured in the same conditions, strongly suggesting that this difference also occurs in vivo, The use of inhibitors in the presence or absence of glucose showed that both lactate and an ATP-driven proton pump sharing some characteristics of the vacuolar H+ pump were involved, Bafilomycin A1, a specific inhibitor of the vacuolar (V-type) ATP-H+ pump inhibited part of the acidification by MCF7 cells, but not by MDA-MB-231 cells, We also used microelectrodes to measure extracellular pH, in close contact to the MCF7 breast cancer cells, The pH at the free surface of MCF7 cells was lower by 0.33 +/- 0.14 unit than that of the surrounding medium, while insertion of the microelectrode tip beneath the attached surface of the cells showed a greater lowering of pH from 0.3 to 1.7 pH unit as long as cell attachment on the substrate prevented H+ diffusion, We conclude that breast carcinoma cells have a higher capacity for acidifying their extracellular milieu than normal mammary cells, and that both a plasma membrane H+-ATPase, and lactic acid production are involved in this acidification. It is therefore possible that the aspartyl and cysteinyl procathepsins secreted in excess by tumor cells may be activated extracellularly in vivo close to the basement membrane.