Liu Yan, Li Yue-Hui, Guo Feng-Jie, Wang Jia-Jia, Sun Rui-Li, Hu Jin-Yue, Li Guan-Cheng
Tumor Immunobiology Laboratory of Cancer Research Institute, Central South University, Changsha 410078, Hunan Province, China.
World J Gastroenterol. 2008 Dec 21;14(47):7175-82. doi: 10.3748/wjg.14.7175.
To investigate the expression pattern of gamma-aminobutyric acid A (GABAA) receptors in hepatocellular carcinoma (HCC) and indicate the relationship among gamma-aminobutyric acid (GABA), gamma-aminobutyric acid A receptor alpha3 subunit (GABRA3) and HCC.
HCC cell line Chang, HepG2, normal liver cell line L-02 and 8 samples of HCC tissues and paired non-cancerous tissues were analyzed with semiquantitative polymerase chain reaction (PCR) for the expression of GABAA receptors. HepG2 cells were treated with gamma-aminobutyric acid (GABA) at serial concentrations (0, 1, 10, 20, 40 and 60 micromol/L), and their proliferating abilities were analyzed with the 3-(4, 5-methylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell doubling time test, colon formation assay, cell cycle analysis and tumor planted in nude mice. Small interfering RNA was used for knocking down the endogenous GABRA3 in HepG2. Proliferating abilities of these cells treated with or without GABA were analyzed.
We identified the overexpression of GABRA3 in HCC cells. Knockdown of endogenous GABRA3 expression in HepG2 attenuated HCC cell growth, suggesting its role in HCC cell viability. We determined the in vitro and in vivo effect of GABA in the proliferation of GABRA3-positive cell lines, and found that GABA increased HCC growth in a dose-dependent manner. Notably, the addition of GABA into the cell culture medium promoted the proliferation of GABRA3-expressing HepG2 cells, but not GABRA3-knockdown HepG2 cells. This means that GABA stimulates HepG2 cell growth through GABRA3.
GABA and GABRA3 play important roles in HCC development and progression and can be a promising molecular target for the development of new diagnostic and therapeutic strategies for HCC.
研究γ-氨基丁酸A（GABAA）受体在肝细胞癌（HCC）中的表达模式，并阐明γ-氨基丁酸（GABA）、γ-氨基丁酸A受体α3亚基（GABRA3）与HCC之间的关系。
采用半定量聚合酶链反应（PCR）分析肝癌细胞系Chang、HepG2、正常肝细胞系L-02以及8例HCC组织及其配对的癌旁组织中GABAA受体的表达情况。用不同浓度（0、1、10、20、40和60 μmol/L）的γ-氨基丁酸（GABA）处理HepG2细胞，通过噻唑蓝（MTT）法、细胞倍增时间检测、集落形成实验、细胞周期分析以及裸鼠成瘤实验分析其增殖能力。利用小干扰RNA敲低HepG2细胞内源性GABRA3的表达，分析GABA处理或未处理的这些细胞的增殖能力。
我们发现HCC细胞中GABRA3过表达。敲低HepG2细胞内源性GABRA3的表达可减弱HCC细胞生长，提示其在HCC细胞活力中发挥作用。我们测定了GABA对GABRA3阳性细胞系增殖的体内外作用，发现GABA以剂量依赖性方式促进HCC生长。值得注意的是，向细胞培养基中添加GABA可促进表达GABRA3的HepG2细胞增殖，但对敲低GABRA3的HepG2细胞无此作用。这表明GABA通过GABRA3刺激HepG2细胞生长。
GABA和GABRA3在HCC的发生发展中起重要作用，有望成为HCC新诊断和治疗策略开发的分子靶点。
