title: Inverse association between methylation of human papillomavirus type 16 DNA and risk of cervical intraepithelial neoplasia grades 2 or 3.
abstract: BACKGROUND
  The clinical relevance of human papillomavirus type 16 (HPV16) DNA methylation has not been well documented, although its role in modulation of viral transcription is recognized.
  
  
  METHODS
  Study subjects were 211 women attending Planned Parenthood clinics in Western Washington for routine Papanicolaou screening who were HPV16 positive at the screening and/or subsequent colposcopy visit. Methylation of 11 CpG dinucleotides in the 3' end of the long control region of the HPV16 genome was examined by sequencing the cloned polymerase chain reaction products. The association between risk of CIN2/3 and degree of CpG methylation was estimated using a logistic regression model.
  
  
  RESULTS
  CIN2/3 was histologically confirmed in 94 (44.5%) of 211 HPV16 positive women. The likelihood of being diagnosed as CIN2/3 increased significantly with decreasing numbers of methylated CpGs (meCpGs) in the 3' end of the long control region (P(for trend) = 0.003). After adjusting for HPV16 variants, number of HPV16-positive visits, current smoking status and lifetime number of male sex partners, the odds ratio for the association of CIN2/3 with ≥4 meCpGs was 0.31 (95% confidence interval, 0.12-0.79). The proportion of ≥4 meCpGs decreased appreciably as the severity of the cervical lesion increased (P(for trend) = 0.001). The inverse association remained similar when CIN3 was used as the clinical endpoint. Although not statistically significant, the ≥4 meCpGs-related risk reduction was more substantial among current, as compared to noncurrent, smokers.
  
  
  CONCLUSIONS
  Results suggest that degree of the viral genome methylation is related to the outcome of an HPV16 cervical infection.
authors: Department of Pathology, School of Medicine, School of Public Health, University of Washington, Seattle, Washington, United States of America. longfu@u.washington.edu
authors: Long Fu
authors: LF
authors: Xi
authors: Mingjun
authors: M
authors: Jiang
authors: Zhenping
authors: Z
authors: Shen
authors: Ayaka
authors: A
authors: Hulbert
authors: Xiao-Hua
authors: XH
authors: Zhou
authors: Ying-Ying
authors: YY
authors: Lin
authors: Nancy B
authors: NB
authors: Kiviat
authors: Laura A
authors: LA
authors: Koutsky
mesh_terms: D018899:CpG Islands; D019175:DNA Methylation; D004279:DNA, Viral / Q000378:metabolism*; D005260:Female; D052162:Human papillomavirus 16 / Q000235:genetics*; D006801:Humans; D011237:Predictive Value of Tests; D012306:Risk; D002583:Uterine Cervical Neoplasms / Q000209:etiology / Q000473:pathology / Q000821:virology*; D002578:Uterine Cervical Dysplasia / Q000209:etiology / Q000473:pathology / Q000821:virology*
chemical_list: D004279:DNA, Viral