Abstract: OBJECTIVE: To study the effect of particulate matter 2.5(PM_2.5) exposure on expression of oncogenes and apoptosis-related genes in normal hepatocytes (L02 cells). METHODS: L02 cells were exposed to PM_2.5 (10 and 50 μg/mL), as the experimental group, to 10 μmol/L Cr⁶⁺ as the positive control group, and nothing as the negative control group,for 24 h. After the treatment,mRNA expression of oncogenes including promoting oncogenes including c-myc, c-fos and suppressing oncogenes p53 and promoting apoptosis-related genes including Caspase-3, Caspase-8 and suppressing apoptosis gene Bcl-2 were detected by fluorescent quantitative real-time PCR(qPCR),the protein expression of oncogenes and apoptosis genes were detected with Western blot. RESULTS: The qPCR showed that compared with the negative control group, significantly different mRNA expressions in the PM_2.5 10 μg/mL,50 μg/mL and positive control groups were:c-myc gene increased by 69.5%,118.0%,51.1%,c-fos gene increased by 50.3%,64.4%,23.3%;p53 gene decreased by 4.0%,22.0%,18.0%;Caspase-3 gene increased by 31.0%,30.5% and 42.0%;Caspase-8 expression level increased by 25.3%,40.3% and 64.5%,Bcl-2 gene expression level decreased by 40.5%,46.9% and 41.4%, respectively (P < 0.05). Western blot analyses showed that expression levels of c-myc protein increased by 32.2%, 49.3%,70.6%;c-fos protein increased by 11.3%,50.2%,45.2%;p53 protein decreased by 17.5%,40.0%, 42.5%;Caspase-3 protein increased by 23.1%,33.9%,43.1%;Caspase-8 protein increased by 31.4%,52.1%, 80.0%; Bcl-2 protein decreased by 14.3%, 23.3%, 36.9%, respectively, (P < 0.05). CONCLUSION: PM_2.5 exposure increased expression of promoting oncogenes and promoting apoptosis genes as well as decreased expression of suppressing oncogenes and suppressing apoptosis genes in L02 hepatocytes. The results indicate that PM_2.5 exposure can promote and activate malignant transformation and apoptosis of L02 hepatocytes.

Key words: PM_2.5, L02 hepatocytes, oncogenes, apoptosis-related genes, gene expression