The Role Of Oxidative Damage And Repair Mechanisms In The Occurrence Of Aflatoxin With Primary Liver Cancer With Chemotherapy Reactivity

ObjectiveTo investigate the status of oxidative stress and repair,and the role of potentially functional polymorphisms of DNA damage repair genes in in vitro cultured lymphocytes exposed to low concentration of Aflatoxin B1(AFB1).MethodsPeripheral blood lymphocytes were collected from ten healthy volunteers and 20 hepatocellular carcinoma(HCC)patients.Oxidative DNA damage levels in lymphocytes exposed to various concentration of AFB1 were examed using flow cytometry.Intracellular superoxide dismutase(SOD),lipid peroxidation products-malondialdehyde(MDA),hydroxyl radicals(OH)and reactive oxygen species(ROS)were also determined.In addition,the expression of DNA repair enzymes(P53,P21,hOGG1,APE and PARP)was analyzed by RT-PCR,and the genotypes of APE and hOGG1 were determined by PCR-CTPP assay.Results1.After AFB1 treatment,8-oxoG levels in the lymphocytes were higher than that in the controls.In contrast to control group,HCC cases had higher levels of 8-oxoG in lymphocytes(P＜0.05).2.Total SOD content in the supernatant was reversly associated with,while the OH~- content in the supernatant increased with the AFB1 concentration. Meanwhile,8-oxoG levels in lymphocytes were associated with both OH~-(r=0.3812,P=0.038)and T-SOD content(r=-0.5539,P=0.001). 3.There were highest levels of mRNA of P53,P21,hOGG1,APE and PARP in lymphocytes at concentration of 20μg/ml AFB1 incubation(in contrast to the blank controls,P＜0.01).4.Individuals carrying APE Glu148Asp or APE Asp148Asp genotypes showed higher levels of DNA damage than those carrying APE Glu148Glu genotypes (P＜0.05).Conclusion1.After AFB1 exposure,the peripheral blood lymphocytes in HCC patients revealed severe oxidative damage than that in health controls.2.After exposure to low concentrations of aflatoxin B1,lymphocytes damage may mainly induced by excessive production of OH~-.3.APE 148Asp genotype is associated with higher level of oxidative damage in this in vitro model thus might have etiology implication for AFB1-related hepatocarcinogenesis. AIMTo explore the expression and clinicopathological implications of human 8-oxoGuanine DNA glycosylase-1(hOGG1)and of poly ADP-ribose polymerase(PARP)in hepatocellular carcinoma(HCC)and cirrhotic livers.METHODShOGG1 and PARP expression was detected by immuneohistochemical EnVision method on liver tissues of non-HCC controls(n=41),cirrhotic(n=51)and HCC patients(n=99).RESULTSThere were three types of hOGG1 and of PARP positive staining in HCCs: nuclear,cytoplasmic and mixed.The expression levels of hOGG1 in nucleus was significantly higher in HCCs than that in hepatocirrhosis and controls,and significantly higher in hepatocirrhosis than that in controls(P＜0.01).The expression levels of PARP in nucleus was significantly lower in HCCs than that in hepatocirrhosis and controls,and significantly lower in hepatocirrhosis than that in controls(P＜0.01).The expression of hOGG1 and of PARP was not associated with the clinicopathological factors in HCCs(P＞0.05).Multiplicity indicated that hOGG1 expression in nucleus was related to ALT(OR=1.022, P=0.041),hOGG1 expression in cytoplasm was related to T bili(OR=1.155, P=0.018),PARP expression in cytoplasm was related to peripheral blood leucocytes(OR=0.757,P=0.037). CONCLUSIONDuring hepatocarcinogenesis,the expression pattern of hOGG1 and PARP in liver cell nucleus might reflect the status of oxidative stress in each stage thus has etiology implications. ObjectiveTo explore the effect of preoperative chemotherapy on DNA repair enzyme of human 8-oxoGuanine DNA glycosylase-1(hOGG1)and of poly ADP- ribose polymerase(PARP)in hepatocellular carcinoma(HCC)patients.MethodshOGG 1 and PARP expression was detected by immuneohistochemical EnVision method in tissues of normalliver(n=41),HCC and the surrounding liver(n=187, preoperative chemotherapy n=88,without preoperative chemotherapy n=99).ResultsThe expression levels of hOGG1 in nucleus was significantly higher in HCCs without preoperative chemotherapy than that undergoing preoperative chemotherapy and normal livers,and significantly higher in HCCs undergoing preoperative chemotherapy than that in normal livers(P＜0.05).The expression levels of PARP in nucleus was significantly lower in HCCs without preoperative chemotherapy than that undergoing preoperative chemotherapy and normal liver,and significantly lower in HCC undergoing preoperative chemotherapy than that in normal livers(P＜0.05).COX multivariate prognosis analysis indicated that the risk factors for HCC to recur were the positive degree of PARP,ALT,the histological grade of HCC.(all P＜0.05)and the protective factor was the counting of lymphocyte(all P＜0.05). ConclusionChemotherapy increases the ability of DNA repair in HCC tissues.To go through screening,the HCC cells with potent capability of DNA repair might be the sourse of recurrence after operation if they escape both preoperative chemotherapy and surgical resection.The PARP expression was the risk factor for HCC relapse.