Possible roles of a tumor suppressor gene PIG11 in hepatocarcinogenesis and As2O3-induced apoptosis in liver cancer cells
Possible roles of a tumor suppressor gene PIG11 in hepatocarcinogenesis and As2O3-induced apoptosis in liver cancer cells
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DOI：
10.1007/s00535-009-0030-1
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发表时间：
2009-05-01
影响因子：
6.3
通讯作者：
Cao, En-Hua
中科院分区：
文献类型：
--
作者：
Liu, Xiao-Min;Xiong, Xiu-Fang;Cao, En-Hua
我们前期的研究表明，p53诱导的基因11 （PIG11）参与了三氧化二砷（As2O3）诱导的人胃癌MGC-803细胞凋亡。我们进一步研究了PIG11在人肝细胞癌（HCC）组织和细胞系中的表达，并比较了HepG2和L-02细胞对as2o3诱导的细胞凋亡的敏感性。使用抗人PIG11抗体，采用免疫组织化学和免疫细胞化学方法检测PIG11在人正常肝组织、HCC组织和细胞系中的表达。采用3-（4,5-二甲基噻唑-2-基）-2,5-二烯基溴化四唑（MTT）法测定细胞活力。流式细胞术检测细胞凋亡。采用逆转录聚合酶链反应（RT-PCR）和Western blotting检测细胞中PIG11 mRNA和蛋白的表达。通过与β -肌动蛋白强度的比较，利用密度测定法计算蛋白质强度。使用小干扰RNA （siRNA）敲低PIG11。我们发现，在HCC组织和细胞系（Bel-7402、SMMC-7721、HepG2细胞）中，PIG11的表达显著下调。此外，HepG2细胞对as2o3诱导的凋亡比L-02细胞更敏感。与L-02细胞相比，HepG2细胞中PIG11 mRNA和蛋白的表达上调幅度更大。放线菌素D或环己亚胺存在时，PIG11蛋白的表达量没有增加。同样，siRNA对PIG11的抑制使as2o3诱导的PIG11蛋白表达降低85%以上，并部分阻止了as2o3诱导的HepG2和L-02细胞凋亡。上述结果表明，PIG11基因可能参与了as2o3诱导的HepG2细胞凋亡，提示PIG11表达的适应性反应是增强细胞对as2o3诱导的凋亡敏感性的重要因素之一。
Our previous studies demonstrated that p53-induced gene 11 (PIG11) was involved in arsenic trioxide (As2O3)-induced apoptosis in human gastric cancer MGC-803 cells. Here, we studied further PIG11 expression in human hepatocellular carcinoma (HCC) tissues and cell lines and compared the sensitivity to As2O3-induced cell apoptosis in HepG2 and L-02 cells.PIG11 expression in human normal liver tissues, HCC tissues, and cell lines was determined by immunohistochemistry and immunocytochemistry methods, using an anti-human PIG11 antibody. Cell viability was estimated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diplenyltetrazolium bromide (MTT) assay. Cell apoptosis was determined by flow cytometry. Reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blotting were performed to analyze PIG11 mRNA and protein expression in cells. Protein intensity was calculated by comparison with the intensity of beta-actin, using densitometry. PIG11 was knocked down using small interfering RNA (siRNA).We found that PIG11 expression was significantly downregulated in HCC tissue and the cell lines (Bel-7402, SMMC-7721, HepG2 cells). Further, HepG2 cells were more sensitive to As2O3-induced apoptosis than L-02 cells. The expression of PIG11 mRNA and protein was upregulated to a greater extent in HepG2 than in L-02 cells. In the presence of actinomycin D or cycloheximide, the amount of PIG11 protein expression did not increase. Likewise, the inhibition of PIG11 by siRNA decreased As2O3-induced PIG11 protein expression by more than 85% and partially prevented As2O3-induced apoptosis in both HepG2 and L-02 cells.The above results demonstrated that the PIG11 gene may be involved in As2O3-induced apoptosis in HepG2 cells and suggested that the adaptive response of PIG11 expression is one of the important factors in enhancing cell sensitivity to As2O3-induced apoptosis.