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[LASS2 interacts with V-ATPase and inhibits cell growth of hepatocellular carcinoma.] [Ariticle in Chinese]

TANG Ning, JIN Jie, DENG Yun, KE Rong-Hu, SHEN Qiu-Jin, FAN Shao-Hua, QIN Wen-Xin

Shanghai Medical College, Fudan University, Shanghai 200032, China； National Laboratory for Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai 200032, China； School of Life Sciences, Jiangsu University, Zhenjiang 212013, China

Abstract

Homo sapiens longevity assurance homologue 2 (LASS2) is a novel gene isolated from a human liver cDNA library by ourlaboratory, and it is a human homologue of the yeast longevity assurance gene LAG1 (Saccharomyces cerevisiae longevity assurancegene). According to our previous results, LASS2 could interact with subunit c of vacuolar type H+-ATPase (V-ATPase), and theoverexpression of LASS2 could inhibit the cell growth of a human hepatocellular carcinoma (HCC) cell line, SMMC-7721. In order tounderstand the role of the interaction between LASS2 and V-ATPase in HCC cell growth, we transiently transfected plasmid pCMVHA2-LASS2 into HCCLM3, a HCC cell line without the significant expression of endogenous LASS2. The pH-sensitive fluorescenceprobes, BCECF and BCECF-AM, were used to measure the intracellular and extracellular H+ concentrations of HCCLM3 cellsrespectively. The effect of LASS2 gene on apoptosis was evaluated with Annexin-V/FITC and propidium iodide (PI) by flow cytometry.Western blot was used to detect cytochrome c (Cyt c) in the cytosol and mitochondria, as well as pro-caspase-3 in cytosol. The resultsshowed that the cell growth of LASS2-transfected HCCLM3 cells was significantly inhibited compared with that of the mock control.LASS2 transfection increased intracellular H+ concentration of HCCLM3 cells, while decreased extracellular H+ concentration. Moreover,LASS2 transfection significantly enhanced the apoptosis of HCCLM3 cells. In LASS2-transfected cells, the amounts of Cyt c increasedin the cytosol, while decreased in the mitochondria. Meanwhile, the expression of pro-caspase-3 in the cytosolic extracts wasdecreased. These results implicate that LASS2 gene might increase intracellular H+ of HCC cells via the interaction with V-ATPase,thereby inducing cell apoptosis through mitochondrial pathway.

Key words: Homo sapiens longevity assurance homologue 2; carcinoma, hepatocellular; cell growth; apoptosis; cytochrome c

Received: 2010-02-09　　Accepted: 2010-04-28

Corresponding author: 覃文新　　E-mail: wqin@shsci.org

Citing This Article：

TANG Ning, JIN Jie, DENG Yun, KE Rong-Hu, SHEN Qiu-Jin, FAN Shao-Hua, QIN Wen-Xin. [LASS2 interacts with V-ATPase and inhibits cell growth of hepatocellular carcinoma.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (3): 196-202 (in Chinese with English abstract).