不同代谢活化系统增强苯并(a)芘诱导人支气管上皮细胞转化效应

目的探讨不同的代谢活化系统在苯并(a)芘[B(a)P]诱导人细胞转化模型中的应用。方法选择人支气管上皮细胞HBETR,采用3种不同的代谢活化方式:分别为加入大鼠S9组分(S9-Mix)、高表达代谢关键酶P450CYP1A1(HBETR-1A1细胞)和染毒前48小时用低剂量B(a)P诱导(HBETR-IN细胞)。通过软琼脂克隆形成试验和裸鼠皮下成瘤试验来比较在不同的代谢活化系统下,间接致癌物B(a)P诱导细胞转化的效能。结果通过蛋白印迹和酶活性检测结果验证HBETR-1A1细胞构建成功。细胞的生物学特性没有明显的改变。20μmol/LB(a)P染毒作用下HBETR-1A1、HBETR-IN细胞出现转化时间均为11周,而未加入活化系统时,HBETR细胞需14周才能获得恶性转化。HBETR细胞在加入和不加入S9-Mix的条件下,转化时间分别是14周、20周。上述转化的效果与CYP1A1酶活性以及蛋白表达水平相一致。结论三种代谢系统都能够促进间接致癌物B(a)P的代谢活化,缩短细胞的转化间期,提高细胞转化效率。从试验操作难度、试验的重复性及结果的可靠性等几个方面比较三种代谢系统应用的可行性,低剂量诱导作为新的代谢活化的方法在细胞转化试验中有着潜在的应用前景。

Metabolic activation of benzo(a)pyrene enhanced transformation of human bronchial epithium cell HBETR

Objective To study the application of different metabolic activation systems in benzo(a)pyrene [B(a)P]-induced human bronchial epithium cell HBETR transformation. Methods In vitro metabolic activations of B (a) P were compared with rat liver S9 fraction mix, overexpression of a key enzyme (P450 CYP1A1), and prior low dose B(a)P (1 μmol/L) induction. Using soft agar assay and tumorigenicity assay, the different metabolic activation systems were compared to the influence on transformation of human bronchial epithium cell HBETR. Results Both immunoblotting and enzyme activity showed that cells overexpressing CYP1A1 (HBETR-1A1) and 48 h after low dose B(a)P induction (HBETR-IN) had high-level expression of CYP1A1. There were no obvious changes in the biology characteristic of these cells. The latencies of cell transformation in HBETR-1A1 and HBETR-IN cells were 11 weeks when cells were treated with B(a)P at concentration of 20μmol/L, while it took 14 weeks to achieve cell transformation in their control cells. The latencies of malignant transformation in HBETR cells in presence or absence of S9-mix were 14 weeks and 20 weeks, respectively. The efficiencies of cell transformation were in consonance with the protein level of endogenous CYP1A1 enzyme and its enzyme activity. Conclusion The three metabolic conditions of the addition of rat liver S9 fraction mix, overexpression of a key enzyme (CYP1A1), and low dose B(a) P induction could enhance the B(a)P metabolic activation and shorten the latency of malignant transformation. In terms of thefeasibility, difficulty of manipulation, stability, and reliability, low dose B(a)P induction could seem to be a prospective system used in metabolic activation in comparison with rat liver S9 fraction mix addition.