Interaction Between Polycyclic Aromatic Hydrocarbons Exposure And CpG Islands Methylation Of RAR-? And MGMT Genes In Cervical Intraepithelial Neoplasia

Objective:Cervical Intraepithelial Neoplasia?CIN?is a precancerous lesion of cervical cancer,and it takes 8-12 years for the development of CIN to cervical cancer.So,finding the key factors that affect the progression of CIN is essential to the prevention of cervical cancer.As is known to us,persistent infection of human papillomavirus?HPV?is the major cause for the development and progression of cervical cancer and CIN.Although women have a high rate of HPV infection,only 1%of HPV-infected women and about 12%of high risk HPV-infected women have progressed to cervical cancer.Therefore,the existence of other factors affecting the development of cervical cancer is inevitable.In recent years,the association between environmental pollution and cervical cancer is gradually attracting the attention of scholars worldwide,DNA methylation is closely related to the development of cervical cancer,and studies have found that exposure to polycyclic aromatic hydrocarbons?PAHs?may cause abnormal DNA methylation.However,the relationship between PAHs and DNA methylation of tumor suppressor gene in cervical lesions has not been reported.Our study aims to explore the role of PAHs in the progress of CIN and the interaction of PAHs and CpG islands methylation of RAR-?as well as MGMT genes,further provide theoretical basis for the etiological study of CIN,and develop new ideas for the decision making and measures instituting for prevention and control of CIN.Methods:In women with the abnormal liquid-based Thinprep cytologic test?TCT?result?diagnosis of TBS system?ASC-US?which selected from the natural population-based cohort established in Jiexiu city and Yangqu County from June 2014 to September,107women with low grade cervical intraepithelial neoplasia?CIN??,98 with high grade cervical intraepithelial neoplasia?CIN?/??and 138 with normal cervix?NC?diagnosed by colposcopy and pathology were selected as our subjects finally.All the subjects were voluntarily signed informed consent and entered the study.A structured questionnaire was used to conduct a face-to-face survey to collect demographic characteristics,lifestyle habits,reproductive status,and past medical history of all subjects.Diversion hybridization was used to detect HPV infection status and typing.The level of 1-OHP in urine was detected by high performance liquid chromatography?HPLC?.Methylation-specific PCR?MSP?was used to detect CpG islands methylation of RAR-?and MGMT genes.The Kruskal-Wallis H test,?² test and Logistic regression were performed by SPSS20.0software.The additive model was used for interaction,and RERI,API and S were evaluated interaction effect.Amos21.0 was used for path analysis,goodness of fit index?GFI?,degree of freedom adjusted GFI?AGFI?,comparison fit index?CFI?,normaed fit index?NFI?,value-added fit index?IFI?,root mean square residual?RMR?evaluates the fitting effect.Results:1.Relationship between HPV infection and cervical intraepithelial neoplasia:The rates of HPVs infection in NC group,CINI group and CINII/III group were 31.9%,44.9%and 63.3%,respectively.The rates of high-risk HPV infection in NC group,CINI group and CINII/III group were 29.7%and 43.0%and 62.2%respectively.And the rates of HPV16 infection in NC group,CINI group and CINII/III group were 6.5%,14.0%and40.8%,respectively.The rates of HPVs,high-risk HPV and HPV16 infection in the CINI group and CINII/III group were higher than in the NC group,respectively,in the CINII/III group were higher than in the CINI group,and with the aggravation of the degree of cervical intraepithelial neoplasia,the rates of HPVs,High-risk HPV and HPV16 infection gradually increased(?²_trend=22.528,P<0.001;?²_trend=24.392,P<0.001;?²_trend=42.014,P<0.001).2.Relationship between the levels of 1-OHP in urine and cervical intraepithelial neoplasia:The distribution of 1-OHP concentrations in the urine was not common among each group?H=64.812,P<0.001?,multiple comparisons showed that the concentration of1-OHP in the CINII/III group was higher than that in the CINI group and NC group.The concentration of 1-OHP in the CINI group was higher than that in the NC group.And with the aggravation of the degree of cervical intraepithelial neoplasia,1-OHP concentrations gradually increased.Further analysis was performed by dividing the median concentration of 1-OHP in the NC group into the low-exposed group??0.07?mol/mol Cr?and the high-exposure group?>0.07?mol/mol Cr?,the results showed that after adjustment for related factors of cervical lesions,1-OHP high exposure increased the risk of CINI?OR=1.72,95%CI:1.02-2.90?and CINII/III?OR=3.92,95%CI:2.14-7.19?.With the aggravation of the degree of cervical intraepithelial neoplasia,the rates of 1-OHP high exposure gradually increased(?²_trend=23.955,P<0.001).There was a positive additive interaction between 1-OHP and HPVs or HR-HPV infection in CINI and CINII/III groups.There was a positive interaction between 1-OHP and HPV16 infection in CINII/III group,but 1-OHP and HPV16 infection did not show interaction in the CINI group.3.Relationship between CpG islands methylation of RAR-?as well as MGMT genes and cervical intraepithelial neoplasia:The CpG islands methylation rates of RAR-?and MGMT genes?19.4%;19.4%?in the CINII/III group were higher than in the NC group?6.5%;5.1%?,the difference was statistically significant??²=9.072,P=0.003;?²=11.979,P=0.001?,but there was no significant difference in the methylation rates of RAR-?and MGMT genes between NC group and CINI group??²=0.316,P=0.574;?²=0.606,P=0.436?;With the aggravation of the degree of cervical intraepithelial neoplasia,the CpG islands methylation rates of RAR-?and MGMT genes gradually increased(?²_trend=9.178,P=0.002;?²_trend=12.302,P<0.001).4.Relationship between 1-OHP levels and CpG islands methylation of RAR-?as well as MGMT gene in cervical intraepithelial neoplasia:The interaction of 1-OHP and Cp G islands methylation of RAR-?and MGMT gene analyzed by additive model in cervical intraepithelial neoplasia revealed that there was a positive additive interaction between1-OHP and CpG islands methylation of RAR-?and MGMT gene in the CINII/III group,but no interaction was observed in the CINI group.Pathway analysis showed that 1-OHP not only had a direct effect on cervical lesions,but also had an indirect effect on cervical lesions through CpG islands methylation of RAR-?and MGMT gene,among which the direct effect is more significant.Conclusion:1.HPVs infection,HR-HPV infection and HPV16 infection could all increase the risk of CIN in women.Therefore,the implementation of HPV screening,especially high-risk HPV screening,helps to reduce the risk of cervical cancer.2.1-OHP high exposure may increase the risk of cervical intraepithelial neoplasia.Therefore,taking effective measures to control environmental pollution and minimizing PAH exposure in daily life are important for controlling the progression of CIN.3.CpG islands hypermethylation of RAR-?and MGMT genes can increase the risk of high grade cervical intraepithelial neoplasia,which could be used as an assistant molecular biomarker in high grade cervical intraepithelial neoplasia stage for early detection of cervical cancer.4.Interaction between 1-OHP high exposure and CpG islands hypermethylation of RAR-?as well as MGMT genes may affect the risk of high grade cervical intraepithelial neoplasia,1-OHP may affect the development of cervical lesions by affecting the Cp G islands methylation of RAR-?and MGMT genes,it provides a theoretical basis for studying the etiology and pathogenesis of CIN,helps to control progression of CIN and delays or even blocks the occurrence and development of cervical cancer.