title: HPV 16 E2 binding sites 1 and 2 become more methylated than E2 binding site 4 during cervical carcinogenesis.
abstract: E2 protein binding to the four E2 binding sites (E2BSs) at the long control region of Human Papillomavirus (HPV) 16/18 genome may exert either transcriptional activation/repression on E6 and E7 oncoproteins. Methylation status at the E2BSs may affect the relative binding of E2 protein to them. In this study, methylation percentage at E2BS 1, 2 (promoter-proximal), and 4 (promoter-distal) were assessed by pyrosequencing and compared among HPV 16/18-positive cervical cancer, high-grade, and low-grade Cervical Intraepithelial Neoplasia, Atypical Squamous Cells of Undetermined Significance, and normal cervical epithelium. HPV 16 E2BS1&2 were more methylated than HPV 16 E2BS4 in cervical cancer whereas in cervical premalignant lesions and normal epithelium, HPV 16 E2BS1&2 were less methylated than HPV 16 E2BS4. HPV 18 E2BS1&2 remained more methylated than E2BS4 in all histological groups. HPV 16 E2BS1&2 methylation increased from high-grade lesions to cervical cancer (P < 0.001). HPV 16 E2BS4 methylation increased from low-grade to high-grade premalignant lesions (P = 0.041). Both HPV 18 E2BS1&2 and E2BS4 methylation increased from low-grade to high-grade Cervical Intraepithelial Neoplasia (P = 0.019 and 0.001 respectively) and further increased form high-grade lesions to cervical cancer (P < 0.001 and 0.005 respectively). Conclusively, HPV 16 E2BS1&2 (for transcriptional repression of E6/E7 oncoproteins) became more heavily methylated than E2BS4 (for transcriptional activation of E6/E7) in cervical cancer, favouring the differential binding of E2 protein to E2BS4. Increasing methylation at HPV 16/18 E2BSs are potentially useful adjunctive molecular markers for predicting progression from low-grade to high-grade cervical premalignant lesions and from high-grade lesions to cervical cancer.
authors: Department of Obstetrics & Gynaecology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China.
authors: Tsin-Wah
authors: TW
authors: Leung
authors: Stephanie S
authors: SS
authors: Liu
authors: Rebecca C Y
authors: RC
authors: Leung
authors: Mandy M Y
authors: MM
authors: Chu
authors: Annie N Y
authors: AN
authors: Cheung
authors: Hextan Y S
authors: HY
authors: Ngan
mesh_terms: D000328:Adult; D000368:Aged; D065309:Atypical Squamous Cells of the Cervix / Q000821:virology; D001665:Binding Sites; D014408:Biomarkers, Tumor / Q000032:analysis; D063646:Carcinogenesis; D045744:Cell Line, Tumor; D002584:Cervix Uteri / Q000821:virology; D019175:DNA Methylation; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004848:Epithelium / Q000821:virology; D005260:Female; D052162:Human papillomavirus 16 / Q000235:genetics*; D052161:Human papillomavirus 18 / Q000235:genetics; D006801:Humans; D008875:Middle Aged; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D050725:Papillomavirus E7 Proteins / Q000235:genetics; D030361:Papillomavirus Infections / Q000235:genetics* / Q000821:virology; D002578:Uterine Cervical Dysplasia / Q000473:pathology / Q000821:virology*
chemical_list: D014408:Biomarkers, Tumor; D004279:DNA, Viral; D004268:DNA-Binding Proteins; C054855:E2 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins
keywords: E2 binding sites methylation; cervical cancer; cervical intraepithelial neoplasia; human papillomavirus (HPV) 16; human papillomavirus (HPV) 18