细胞外的酸性微环境对肝细胞癌细胞生物学行为的影响及其机制

Hepatocellular carcinoma (HCC) is a frequent cancer worldwide and the most frequent type of liver cancer.Increasing evidence suggests that HCC carcinogenesis is a complex process that can involve various modifications to a number of molecular pathways as well as genetic alterations, ultimately leading to malignant transformation and HCC progression. It is known that the tumor acidic microenvironment plays an important role in the promotion and progression of malignant tumor. Our recent study revealed that mRNA and protein expressions of vacuolar H+-ATPase (V-ATPase) ATP6L in native human HCC tissues were markedly up-regulated in comparison with human normal live tissues. V-ATPase ATP6L conspicuously resided on the plasma membrane of native human HCC cells, in addition to its distribution in intracellular organelles, and was involved in the regulation of proton fluxes in human HCC cells. The acidification of extracellular milieu stimulated the intracellular Ca2+ increase of HCC cells. Since intracellular Ca2+ is a ubiquitous cellular signal, its change may control various cellular processes relevant to the development and progression of tumor, such as proliferation, apoptosis, motility, gene transcription and angiogenesis. Our results indicated that intracellular Ca2+ signaling might mediate effect of extracellular acidic microenvironment on the biologic behavior of HCC cells. However, the role of the extracellula acidic microenvironment in the proliferation, invasion, apoptosis, and metastasis of HCC cells is not clear. In the present study, we will investigate the role of the extracellula acidic microenvironment in the proliferation, invasion, apoptosis, and metastasis of HCC cells and its mechanisms. Our aims are to elucidate the cellular and molecular mechanisms of the promotion and progression of HCC and hope to find key control molecules or proteins in the promotion and progression of HCC, and to seek for new potential therapeutic targets against HCC.

肝细胞肝癌是我国最常见的恶性肿瘤之一，其发生是一个复杂的过程，累及了对许多信号通路的调节以及基因改变，最终导致肝细胞的恶性转化和肝细胞癌的发生发展。大量的研究表明肿瘤细胞的酸性微环境在恶性肿瘤的发生和进展中起着重要的作用。我们最近的研究发现人的肝细胞癌细胞的V-ATPase被明显上调，而且大量的存在于肝细胞癌细胞的细胞膜，调节了肝细胞癌细胞内氢离子的排除。同时发现细胞外的酸化刺激了肝细胞癌细胞内钙离子浓度的增加，提示细胞内钙离子信号很可能介导了细胞外酸性微环境对肝细胞癌细胞生物学行为的作用。然而细胞外的酸性微环境在肝细胞癌细胞生长、侵袭、凋亡、转移等生物学行为中的作用及其作用机制不清楚，我们将对其进行进一步研究，希望通过本研究能够揭示肝细胞癌发生发展的细胞分子机制，发现在肝细胞癌发生发展过程中的关键调控分子，为肝细胞癌的治疗提供新的药物治疗靶点。

肿瘤微环境在肿瘤恶性肿瘤中起关键作用。已经证实，肿瘤细胞中的细胞外酸度有助于恶性肿瘤的进展和转移。质子门控阳离子通道的酸敏感离子通道（ASICs），可以被细胞外低pH值低下所激活，参与一些肿瘤如胰腺癌和胃癌的发病机制。在这项研究中，我们调查了ASIC在人类肝细胞癌（HCC）进程中的作用。ASIC1在人肝癌组织中的表达显着增加，主要位于肝癌细胞膜上，且人肝癌组织中ASIC1的表达水平与肝癌的分期和预后呈正相关。在低pH条件下培养24小时，人肝癌细胞Huh7和SK-HEP1中ASIC1的mRNA和蛋白表达水平显着上调。细胞外酸度可促进Huh7和SK-HEP1细胞的增殖、迁移和侵袭，并诱导HCC细胞的上皮 - 间充质转化。ASIC1抑制剂或ASIC1 shRNA抑制胞外酸性诱导的Huh7和SK-HEP1细胞的增殖、迁移、侵袭和上皮 - 间质转化。此外，细胞外酸度诱导HCC细胞内钙离子浓度增加。ASIC1抑制剂或ASIC1 shRNA抑制细胞外酸性诱导的细胞内钙离子浓度增加。进一步的研究结果表明，细胞内钙离子螯合剂BAPTA-AM显着抑制酸性诱导的肝癌细胞的增殖，迁移，侵袭和EMT。 ASIC1 shRNA在HCC细胞中显著抑制HCC细胞生长和小鼠肺转移和肝转移。综上所述，ASIC1介导细胞外酸度诱导的HCC细胞内钙信号改变影响细胞增殖，迁移和侵袭，促进HCC的进展，表明ASIC1可以作为HCC的预后指标和治疗靶点。