Gene Expression Changes in Primary Human Nasal Epithelial Cells exposed to Formaldehyde in vitro. Homo sapiens

Using various exposure conditions, we studied the induction of DNA-protein crosslinks (DPX) by formaldehyde (FA) and their removal in primary human nasal epithelial cells (HNEC). DPX were indirectly measured by the alkaline comet assay as the reduction of gamma ray – induced DNA migration. DPX are the most relevant primary DNA alterations induced by FA and the comet assay is a very sensitive method for the detection of FA-induced DPX. In parallel experiments, we investigated changes in gene expression by using a full genome human microarray. After a single treatment with FA (50 to 200 µM), concentration – and time-dependent changes in gene expression were seen under conditions that also induced genotoxicity. Repeated treatments with low FA concentrations (20 and 50 µM) did not lead to a significant induction of DPX but repeated treatments with 50 µM FA changed the expression of more than 100 genes. Interestingly, the expression of genes involved in the main pathway for FA detoxification and the repair of DPX were not specifically enhanced. A high degree of overlap was seen among the pattern of gene changes induced by FA in HNEC in comparison to recently published array studies for nasal epithelial cells from rats exposed to FA in vivo. Our results suggest that HNEC are a suited in vitro model for the characterization of FA-induced toxicity and the relationship between genotoxic and other cytotoxic effects. Overall design: 39 arrays: several time points and doses of formaldehyde

本研究通过多种暴露条件，探究了甲醛（formaldehyde, FA）诱导的DNA-蛋白质交联（DNA-protein crosslinks, DPX）在原代人鼻上皮细胞（primary human nasal epithelial cells, HNEC）中的形成与清除过程。研究通过碱性彗星试验（alkaline comet assay）间接检测DPX，即以γ射线诱导的DNA迁移率降低作为检测指标。DPX是FA诱导的最具相关性的原发性DNA损伤，而彗星试验是检测FA诱导DPX的高灵敏方法。并行实验中，我们采用全基因组人类微阵列（full genome human microarray）分析基因表达变化。经单次FA处理（浓度范围为50至200 µM）后，在同时诱导遗传毒性的条件下，观察到浓度依赖性与时间依赖性的基因表达改变。采用低浓度FA重复处理（20与50 µM）未显著诱导DPX形成，但50 µM FA的重复暴露可改变超过100个基因的表达。值得注意的是，参与FA解毒及DPX修复主要通路的基因表达并未出现特异性上调。与近期发表的大鼠体内甲醛暴露鼻上皮细胞微阵列研究相比，FA在HNEC中诱导的基因表达变化模式存在高度重合性。本研究结果提示，HNEC是用于表征FA诱导毒性以及遗传毒性与其他细胞毒性效应之间关联的适宜体外模型。整体实验设计：共设置39张微阵列芯片，涵盖不同处理时间点与甲醛剂量梯度。