HBx及其羧基末端40个氨基酸对SMMC-7721肝细胞增殖的影响

目的研究HBx羧基末端40个氨基酸对肝癌细胞增殖的影响及作用机制。方法用HBx及去除羧基末端40个氨基酸HBx3′40转染含野生型(wt)p53的SMMC7721细胞,经稳定筛选后,通过细胞生长曲线绘制以及平板克隆形成实验来观察HBx对细胞增殖的影响,并通过裸鼠体内的成瘤实验观察各移植瘤的大小及重量、增殖细胞核抗原(PCNA)表达的变化。结果细胞生长曲线表明HBx及HBx3′40的细胞生长速度明显较空载体增快;平板克隆形成试验表明克隆形成率,HBx组(48.7±8.1)%及HBx3′40组(82.8±6.0)%较对照组(26.9±3.5)%明显增多(P<0.05),pcDNA3HBx3′40组又较pcDNA3HBx组增多(P<0.05)。裸鼠成瘤实验pcDNA3HBx3′40组肿瘤的大小及重量(1.476±0.232、0.987±0.279)%及pcDNA3HBx组(0.412±0.212、0.395±0.159)%较对照组(0.051±0.024、0.033±0.004)%明显增大(P<0.05),肿瘤细胞的PCNA表达率pcDNA3HBx3′40组(69.25±3.77)%及pcDNA3HBx组(59.00±2.58)%也较对照组(37.67±2.52)%明显增强(P<0.05),且以HBx3′40组的表现更为明显(P<0.05)。结论HBx的羧基末端40个氨基酸可刺激细胞增殖,其突变可能与肝癌细胞发生过程中促进癌细胞的恶性转化有关。

Hepatitis B virus and deletion of its COOH-terminal forty amino acids: proliferative impact on hepatoma cell line SMMC-7721

OBJECTIVE: To explore the biological impact of 40 amino acid deletion at the C-terminal of hepatitis B virus X on the proliferation of hepatoma cells. METHODS: Cells of SMMC-7721 hepatoma cell line were transfected with HBx and its derivative HBx3'-40, harboring the 40 amino acid deletion at the distal C-terminal region. Cell growth curve, colony formation in soft agar plate and tumorigenesis assay in nude mice were used to observe the alterations induced by the transfection of HBx and HBx3'-40. The expression level of PCNA in tumor cells was also investigated. RESULTS: The growth rates of the cells transfected with HBx and HBx3'-40 were markedly increased as compared with that of the control group. The colony formation rates were enhanced in the cells transfected with HBx(48.7 +/- 8.1) and HBx3'-40 (82.8+/-6.0), comparing with the control (26.9 +/- 3.5) %. In the tumorigenic assay, the size and weight of tumors were significantly increased in the cells transfected with HBx (0.412 +/- 0.212, 0.395 +/- 0.159) % and HBx3'-40 (1.476 +/- 0.232, 0.987 +/- 0.279) %, as compared with the control group (0.051 +/- 0.024, 0.033 +/-0.004) %. The expression level of PCNA in tumors was increased in both HBx (59.00 +/- 2.58) % and HBx3'-40 (69.25 +/- 3.77) % transfected cells, comparing with the control (37.67 +/- 2.52) %. Overall, the cells transfected with HBx3'-40 demonstrated the highest proliferative capacity. CONCLUSION: The deletion of 40 amino acids in the C-terminal of HBx is correlated with an enhanced proliferation of hepatoma cells and may play an important role in the malignant transformation of the liver.