Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi 563003, China.
Carcinogenesis. 2012 Dec;33(12):2432-40. doi: 10.1093/carcin/bgs277. Epub 2012 Sep 7.
Tumor cells often exist in a hypoxic microenvironment, which produces acidic metabolites. To survive in this harsh environment, tumor cells must exhibit a dynamic cytosolic pH regulatory system. Vacuolar H(+)-adenosine triphosphatase (V-ATPase) is considered to play an important role in the regulation of the acidic microenvironment of some tumors. In this study, we made an investigation on the expression and functional role of V-ATPase in native human hepatocellular carcinoma (HCC). The results showed that the messenger RNA and protein expression levels of V-ATPase subunit ATP6L in native human HCC tissues were markedly increased, compared with normal liver tissues. Immunohistochemical analysis further confirmed the enhanced expression of V-ATPase ATP6L in human HCC cells and revealed that V-ATPase ATP6L was distributed in the cytoplasm and plasma membrane of HCC cells. The results from immunofluorescence and biotinylation of cell surface protein showed that V-ATPase ATP6L was conspicuously located in the plasma membrane of human HCC cells. Bafilomycin A1, a specific V-ATPase inhibitor, markedly slowed the intracellular pH (pHi) recovery after acid load in human HCC cells and retarded the growth of human HCC in orthotopic xenograft model. These results demonstrated that V-ATPase is up-regulated in human HCC and involved in the regulation of pHi of human HCC cells. The inhibition of V-ATPase can effectively retard the growth of HCC, indicating that V-ATPase may play an important role in the development and progression of human HCC, and targeting V-ATPase may be a promising therapeutic strategy against human HCC.
肿瘤细胞常存在于低氧微环境中，产生酸性代谢物。为了在这种恶劣的环境中生存，肿瘤细胞必须表现出动态的细胞质 pH 调节系统。液泡型 H(+)-三磷酸腺苷酶 (V-ATPase) 被认为在一些肿瘤酸性微环境的调节中发挥重要作用。在本研究中，我们研究了 V-ATPase 在天然人肝癌 (HCC) 中的表达和功能作用。结果表明，与正常肝组织相比，天然人 HCC 组织中 V-ATPase 亚基 ATP6L 的信使 RNA 和蛋白表达水平明显增加。免疫组织化学分析进一步证实了 V-ATPase ATP6L 在人肝癌细胞中的增强表达，并揭示了 V-ATPase ATP6L 分布在 HCC 细胞的细胞质和质膜中。免疫荧光和细胞表面蛋白生物素化的结果表明，V-ATPase ATP6L 明显位于人 HCC 细胞的质膜上。一种特异性的 V-ATPase 抑制剂巴弗洛霉素 A1 显著减缓了人 HCC 细胞内酸负荷后细胞内 pH (pHi) 的恢复，并在原位异种移植模型中减缓了人 HCC 的生长。这些结果表明 V-ATPase 在人 HCC 中上调，并参与了人 HCC 细胞 pHi 的调节。V-ATPase 的抑制可有效减缓 HCC 的生长，表明 V-ATPase 可能在人 HCC 的发展和进展中发挥重要作用，针对 V-ATPase 可能是一种有前途的治疗人 HCC 的策略。
