The Relationship Between DNA Damage In Hematopoietic Tissue And XPD Gene Expression And Methylation Of SD Rats Induced By Benzene

Objective: To investigate the mechanism of XPD gene methylation and expression in benzene induced SD rat hemopoietic tissue injury. Methods: 30 male SD rats were randomly divided into 5 groups, each group with 6 rats, they were blank control group(without any treatment), solvent control group(with corn oil), low dose group(200mg/kg), medial dose group(400mg/kg), high dose group(800mg/kg), each treatment group were given by gavage once a day for 28 days except blank control group. After the gavage, 1. After the rats were killed, femur was observed the pathohistology structure changing by HE dyeing; 2. DNA damage in peripheral blood and bone marrow cells of rats were detected by single cell gel electrophoresis(SCGE); 3. The real-time quantitative PCR with Taqman probe was used to detect the XPD m RNA’s level of bone marrow cell; 4. The Western Blotting was used to detect the expression level of XPD protein of bone marrow cells; 5. The Bisulfate sequencing method is used to detect methylation status of the XPD gene of blood and bone marrow cell. Results: 1. Pathological result suggested, with the dose increased, there was obvious fracture phenomenon in bone trabecular, there was disorder arrangement in cartilage cell, cell rupture, hematopoietic cell decreased, triglyceride droplets increased; 2. The comet experiment results suggested, benzene treatment can lead to cellular DNA damage, and the damage effect was dose-dependent; 3. The real-time quantitative PCR with Taqman probe results: the bone marrow cell XPD m RNA expression in each experiment group(0.600±0.0484)、(0.454±0.331)、(0.501±0.446)、(1.068±0.666)、(1.072±0.047)respectively, compared with blank control group, there was statistically difference in medial dose group and high dose group(P<0.05); 4.The Western Blotting results suggested, the bone marrow cell XPD protein expression in each experiment group(102.78±2.32)%、(100.00±0.00)%、(135.68±13.67)%、(154.48±9.78)%、(176.55±11.05)%respectively, compared with control group, there was statistically difference(P<0.05), there was statistically difference between each dose group(P<0.05); 5. The Bisulfate sequencing method results display: The methylation rate of each experimental group in bone marrow cell are 0.60%、0.30%、1.40%、1.10%、0.80% respectively, compared with control group, there was no significant difference(P>0.05); The methylation rate of each experimental group in blood cell are 2.20%、0.80%、3.10%、1.70%、2.20% respectively, compared with control group, there was no significant difference(P>0.05). Conclusion: Benzene can lead to DNA damage significantly of SD rat’s bone marrow cells and blood cells, the mechanism may be related to up-regulation of XPD gene expression, while methylation of XPD gene may be not involved in transcriptional regulation.