Department of Environmental Health, West China School of Public Health, Sichuan University, Chengdu, Sichuan, People's Republic of China.
Toxicology. 2013 Jul 5;309:73-80. doi: 10.1016/j.tox.2013.04.017. Epub 2013 May 4.
To explore the relationship between DNA polymerase β (pol β) overexpression and benzo[a]pyrene (BaP) carcinogenesis.
Firstly, mouse embryonic fibroblasts that express wild-type level of DNA polymerase β (pol β cell) and high level of pol β (pol β oe cell) were treated by various concentrations of BaP to determine genetic instability induced by BaP under differential expression levels of pol β. Secondly, malignant transformation of pol β cells by low concentration of BaP (20 μM) was determined by soft agar colony formation assay and transformation focus assay. Thirdly, the mRNA and protein levels of BaP-transformed pol β cells (named pol β-T cells) was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot, and the genetic instability of these cells were examined by HPRT gene mutation assay and random amplified polymorphic DNA (RAPD) assay.
Pol β cells were successfully transformed into malignant pol β-T cells by an exposure to low concentration of BaP for 6 months. Pol β-T cells exhibited increased levels of pol β gene expression, HPRT gene mutation frequency and polymorphisms of RAPD products that were comparable to those of pol β oe cells.
Pol β overexpression and its-associated genetic instability may play a key role in BaP carcinogenesis.
探讨 DNA 聚合酶 β（pol β）过表达与苯并[a]芘（BaP）致癌作用的关系。
首先，用不同浓度的 BaP 处理表达野生型 pol β （pol β 细胞）和高水平 pol β （pol β oe 细胞）的小鼠胚胎成纤维细胞，以确定在 pol β 差异表达水平下 BaP 诱导的遗传不稳定性。其次，用低浓度 BaP（20 μM）测定 pol β 细胞的恶性转化，用软琼脂集落形成试验和转化焦点试验测定。第三，用逆转录-聚合酶链反应（RT-PCR）和 Western blot 测定 BaP 转化的 pol β 细胞（命名为 pol β-T 细胞）的 mRNA 和蛋白水平，并通过 HPRT 基因突变试验和随机扩增多态性 DNA（RAPD）试验检测这些细胞的遗传不稳定性。
pol β 细胞经低浓度 BaP 暴露 6 个月成功转化为恶性 pol β-T 细胞。pol β-T 细胞表现出高水平的 pol β 基因表达、HPRT 基因突变频率和 RAPD 产物的多态性，与 pol β oe 细胞相当。
pol β 过表达及其相关的遗传不稳定性可能在 BaP 致癌作用中发挥关键作用。
