| Objetive:Infection of human papilloma virus(HPV) is major cause of cervical cancer and cervical intraepithelial neoplasias(CIN), but not the only. As cervical precancerous lesion, CIN will experience 8-10 years or so from low to high level and finally progress to cervical cancer. Especially low-level stage lesions is reversible, therefore, to find other factors that influence the pathological progress of cervical cancer has great significance of prevention and cure cervical cancer. DNA methylation as the main content of epigenetics has closely related to many tumors, especially the hypermethylation of suppressor gene promoter region Cp G island is an early feature events of many tumors. Folate as a methyl donor involved in DNA methylation process, which formed the inherent biological connection between folate and DNA methylation. Although there have studies shown folate and DNA methylation is associated with the occurrence and development of cervical cancer. But the interaction between HPV, folate and suppressor gene DNA methylation of suppressor gene in cervical cancinogenesis is still lack of evidence. The aim of this study is to explore the effect of HPV, folate and related suppressor gene Cp G island methylation in cervical intraepithelial neoplasias and related interaction, which may provide new orientation to the prevention and treatment of cervical precancerous lesion. Methods:From the community cervical lesions study queue that our research group established in Jiexiu and Yangqu of Shanxi Province from June to December of 2014, selecting patients of low-grade cervical intraepithelial neoplasia(CINⅠ,147), heigh-grade cervical intraepithelial neoplasia(CINⅡ/Ⅲ,134) and 156 participants of normal cervical(NC) who group matched with residence and age, they were experienced thinprep cytologic test(TCT), colposcopy examination screening and finally diagnosed with pathology. Relevant information of subjects was collected through structural questionnaire including demographic characteristics, behavior and health of sexual, reproductive factors, and medical history and so on. HPV was detected by Flow-through hybridization. Chemiluminescence assay was adopted to test the level of serum folate. Methyl-specific PCR(MSP) was used to detect the methylation status. The data were analyzed with the method of chi-square test, Kruskal-Wallis H test, logistic regression and factorial analysis by using SPSS statistical software(version 16.0). The interaction between two factors was analyzed by additive model and RERI, AP, S. The interaction of multiple factors was analyzed Generalized Multifactor Dimensionality reduction(GMDR). Results:(1) The relation between HPV and CIN: HPVs and HPV16 infection rates in CINⅠ(44.9%; 14.2%) and CINⅡ/Ⅲ(67.2%; 46.3%) were all higher than that in NC(36.5%;9.0%) group. Rates of HPVs and HPV16 infection increased gradually with the increase of cervical lesions(c2趋势=26.43,P<0.001;c2趋势=55.63,P<0.001).There has statistically difference between CINⅡ/Ⅲand NC group of HPVs and HPV16 infection rates(c2=26.14,P<0.001;c2=43.29,P<0.001),but there hasn`t statistically difference between CINⅠand NC group(c2=2.19,P=0.139;c2=2.55,P=0.111).(2) The relation between serum folate and CIN: The levels of serum folate was different for the subjects of the three groups(H=130.73, P<0.001). Serum folate levels differed significantly in any two of them(P<0.017). Data from grouping analysis shows that the risks of the CINⅠand CINⅡ/Ⅲ were highed with the levels of serum folate descended(c2趋势=42.48,P<0.001;c2趋势=106.31,P<0.001).Serum folate deficiency and HPV16 infection had additive interaction in cervical intraepithelial neoplasia.(3)The relation between suppressor gene Cp G island methylation and CIN:The methylation rates of p16,FHIT,RAR-βand MGMT in CINⅠgroup(12.9%,17.0%,8.8%,7.5%)and in CINⅡ/Ⅲgroup(13.4%,19.4%,23.9%,17.9%)were higher in NC group(4.5%,7.1%,5.8%,3.8%).The trend of p16,FHIT,RAR-βand MGMT methylation increased gradually with the severity of the cervix lesions(χ2趋势=6.66,P=0.010;χ2趋势=9.32,P=0.002;χ2趋势=21.09,P(27)0.001;χ2趋势=16.35,P(27)0.001).But RAR-βand MGMT methylation rates hasn`t statistically difference between CINⅠand NC group.HPV16infection or serum folate deficiency and p16,FHIT,RAR-βand MGMT hypermethylation had additive interaction in cervical intraepithelial neoplasia.(4) The interactions of HPV, serum folate and suppressor gene methylation in CIN: The potential interactions wered analyzed by the generalized multifactor dimension reduction(GMDR), the best interaction model has highest the accuracy of the test sample and cross validation consistency. The results showed the best interaction model of CINⅠgroup is serum folate, p16 and FHIT methylation. But the best interaction model of CINⅡ/Ⅲgroup is serum folate, HPVs, HPV16 and RAR-β methylation. Conclusions:(1) HPVs or HPV16 infection could increased the risk of CIN Ⅱ/Ⅲ.(2) Serum folate deficiency is associated with an increased risk of cervical intraepithelial neoplasia occurred. Maybe there is a synergistic effect between serum folate deficiency and HPV16 infection in cervical intraepithelial neoplasia, suggesting that both of them exist may increased the risk of CIN.(3) The hypermethylation of P16, FHIT, RAR-β and MGMT Cp G island is associated with an increased risk of CIN Ⅱ/Ⅲ. The methylation rates of P16 and FHIT Cp G island may increased the risk of CINⅠ, suggesting P16、FHIT gene Cp G island hypermethylation may be used as a molecular marker of early cervical lesions and RAR-β、MGMT gene Cp G island hypermethylation may be used as a molecular marker of cervical lesions weighted.(4) Maybe there is a synergistic effects between serum HPV16 infection or serum folate deficiency and P16、FHIT、RAR-β、MGMT Cp G island hypermethylation in cervical intraepithelial neoplasia, suggesting that both of them exist may increased the risk of CIN.(5) The interaction of serum folate and methylation of P16, FHIT Cp G island may influenced the risk of CINⅠ. The interaction of serum folate, HPVs, HPV16 and RAR-β Cp G island methylation may influenced the risk of CIN Ⅱ/Ⅲ. Suggesting that the happening of cervical intraepithelial neoplasia may regulated by the interaction of environment, viruses and genes. |
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