Case–control study of HLA-G promoter methylation status, HPV infection and cervical neoplasia in Curitiba, Brazil: a pilot analysis

Abstract

BackgroundThe causal association between persistent human papillomavirus (HPV) infection and cervical cancer has been established, but the mechanisms that favor HPV persistence in cervical cells are still unknown. The diminished capability of the immune system to control and resolve HPV infection is one of several hypotheses. The tolerogenic protein HLA-G has shown aberrant expression in a variety of cancers, which has been suggested as a mechanism for tumor escape from immunosurveillance. In the present study we evaluate the role of epigenetic modification (promoter de-methylation) of the HLA-G gene on susceptibility to HPV infection and development of high-grade cervical lesions.MethodsA case–control study was carried out in Curitiba, Brazil, between February and June 2010. A total of 789 women aged 15–47 years were recruited: 510 controls with normal cervical cytology, and 279 cases with histologically confirmed cervical intraepithelial neoplasia grade 2 (CIN2, N = 150) or grade 3 (CIN3, N = 129). All women were administered a questionnaire by interview, which collected information on demographic and lifestyle factors, and a cervical sample was collected. HPV DNA detection was performed by GP5+/GP6+ primer-mediated PCR. HPV-positive samples were genotyped by multiplex PCR. A pilot analysis of HLA-G promoter methylation was carried out in a subset of the study population (96 cases and 76 controls) by pyrosequencing. HLA-G methylation and HPV infection status of cases and controls were compared, and confounding factors were computed by t Student and non-parametric Wilcoxon tests. Comparison of HLA-G methylation between cases and controls was assessed by the Bonferroni correction. The association of HLA-G methylation with CIN2/3 was evaluated by logistic regression.ResultsHPV prevalence was 19.6% in controls and 94.3% in CIN2/3 cases. HPV16, 31, 33, 35 and 18 were the most prevalent types. Methylation analysis of seven CpGs in the HLA-G promoter did not reveal any spontaneous de-methylation events in CIN2/3 cases (mean proportion of methylation: 75.8%) with respect to controls (mean 73.7%; odds ratio 1.01, 95% confidence interval 0.96, 1.07).ConclusionsThis study did not support the hypothesis that spontaneous de-methylation events in the HLA-G promoter play a primary role in promoting escape from immunosurveillance in the development of precancerous cervical lesions.

HLA-G Molecules in Autoimmune Diseases and Infections

“…These results are in agreement with the low levels of HLA-G5 expression in cervical cancer ( 136 ). On the other hand, two researches recognized HLA-G 14bp DEL allele and + 3142C as associated with increased risk of cervical cancer ( 137 , 138 ), in agreement with increased expression of HLA-G in cervical cancer tissues ( 139 ) and with the spontaneous de-methylation of HLA-G promoter that allows immune-evasion and the development of precancerous cervical lesions ( 140 ). HLA-G has been also implicated in nasal polyposis development in the presence of HPV infection ( 141 ).…”

Greater expression of the human leukocyte antigen-G (HLA-G) and interleukin-17 (IL-17) in cervical intraepithelial neoplasia: analytical cross-sectional study

“…15 To our knowledge, the present study is the first to explore Many studies have discussed the role of HLA-G and IL-17 in various types of cancer. 16,20 However, this is the first study …”

The Role of HLA-G in Human Papillomavirus Infections and Cervical Carcinogenesis

“…Further evidence for the role of genetic factors in HPV infections and the carcinogenic process was provided by studies that showed an association with specific HLA-G coding region polymorphisms (96)(97)(98)(99)(100)(101)(102)(103)(104). Among the Canadian population, the HLA-G * 01:01:02 and HLA-G * 01:03 alleles were found to be related to an increased risk of HPV16 infection and persistent infections (96), while the HLA-G * 01:01:03 and HLA-G * 01:01:05 alleles were identified as significant predictors of cumulative coinfections over the follow-up period (97).…”