广西乙肝病毒/黄曲霉毒素B1双暴露人肝细胞癌中PTEN mRNA表达及突变的初步研究

目的探讨乙肝病毒/黄曲霉毒素B1双暴露相关肝细胞性肝癌(HCC)中PTEN基因的突变特点及其mRNA的表达水平。方法 108例HCC来自广西不同地区样本,按照乙肝病毒与黄曲霉毒素的暴露情况,分为4个亚组:A组:HBV(+)/AFB1-DNA(+),共48例;B组:HBV(+)/AFB1-DNA(-),共27例;C组:HBV(-)/AFB1-DNA(+),共19例;D组:HBV(-)/AFB1-DNA(-),共14例。采用PCR联合基因直接测序法,检测108例肝癌组织中PTEN基因第4、5、8外显子的突变情况。同时采用RT-PCR法检测其基因mRNA的表达状况。结果①PTEN基因第4、5、8外显子测序结果未发现发生在外显子上的突变。但在第4外显子与第4内含子交界处有61例发生大片段的缺失,缺失率为56.4%。②PTEN缺失率在A、B、C、D组中分别为60.4%、62.9%、47.3%和46.6%,其差异在4个亚组间均无统计学意义(P>0.05)。③PTEN mRNA在4个亚组中的表达半定量灰度值分别为:A组:0.54±0.13;B组:0.59±0.16;C组:0.97±0.16;D组:0.92±0.13。其中,A、B组分别与C、D组相比,其差异均具有统计学意义(PAC=0.002,PAD=0.032,PBC=0.000,PBD=0.011)。结论在广西乙型肝炎病毒/黄曲霉毒素B1的双暴露肝细胞癌中,PTEN mRNA的表达下调是一个常见的分子生物学事件,PTEN mRNA表达下调可能主要与HBV感染有关。AFB1对PTEN mRNA的表达下调可能有协同作用。

PTEN genetic mutations and mRNA expression in cases of human hepatocellular carcinoma exposed to hepatatitis B virus and aflatoxin B1 in Guangxi

Objective To explore gene mutations and mRNA expression of PTEN in cases of hepatocellular carcinoma(HCC) exvposed to both hepatitis B virus and aflatoxin B1(HBV/AFB1).Methods A total of 108 cases of HCC from different districts of Guangxi were divided into 4 groups according to their exposure to HBV and AFB1:group A,HBV(+)/AFB1-DNA(+),48 cases;group B,HBV(+)/AFB1-DNA(-),27 cases;group C,HBV(-)/AFB1-DNA(+),19 cases;and group D,HBV(-)/AFB1-DNA(-),14 cases.PTEN mutations in exons 4,5,and 8 were detected by PCR and direct sequencing,and mRNA expression was analyzed by RT-PCR.Results PTEN mutations in exons 4,5,or 8 were not found in any of the cases.However,a large deletion at the junction of exon 4 and intron 4 was found in 61 cases,corresponding to a deletion rate of 56.4%.The rate of PTEN deletion was 60.4% in group A,62.9% in group B,47.3% in group C and 46.6% in group D.The deletion rate was not statistically significant among the four sub-groups.Semi-quantitative gray values of the PTEN mRNA expression assay were as follows:group A,0.54 ± 0.13;group B,0.59± 0.16;group C,0.97 ± 0.16;group D,0.92 ± 0.13.The pair of groups A/B and the pair C/D differed significantly from each another in PTEN mRNA expression(PAC=0.002,PAD=0.032,PBC=0.000,PBD=0.011).Conclusions Down-regulation of PTEN mRNA expression is a frequent molecular event in HCC involving double exposure to HBV/AFB1 in Guangxi,and it may be related to HBV infection.AFB1 and HBV may act synergistically to down-regulate PTEN mRNA levels.