Combined detection of cell adhesion molecule 1 (CADM1) and T-lymphocyte maturation-associated protein (MAL) promoter methylation in cervical scrapes is a promising triage strategy for high-risk human papillomavirus (hrHPV)-positive women. Here, CADM1 and MAL DNA methylation levels were analysed in cervical scrapes of hrHPV-positive women with no underlying high-grade disease, high-grade cervical intraepithelial neoplasia (CIN) and cervical cancer. CADM1 and MAL methylation levels in scrapes were first related to CIN-grade of the corresponding biopsy and second to CIN-grade stratified by the presence of 'normal' or 'abnormal' cytology as present in the accompanying scrape preceding the cervical biopsy. The scrapes included 167 women with ≤ CIN1, 54 with CIN2/3 and 44 with carcinoma. In a separate series of hrHPV-positive scrapes of women with CIN2/3 (n = 48), methylation levels were related to duration of preceding hrHPV infection (PHI; <5 and ≥ 5 years). Methylation levels were determined by quantitative methylation-specific PCR and normal cytology scrapes of hrHPV-positive women with histologically ≤ CIN1 served as reference. CADM1 and MAL methylation levels increased proportional to severity of the underlying lesion, showing an increase of 5.3- and 6.2-fold in CIN2/3, respectively, and 143.5- and 454.9-fold in carcinomas, respectively, compared to the reference. Methylation levels were also elevated in CIN2/3 with a longer duration of PHI (i.e. 11.5- and 13.6-fold, respectively). Moreover, per histological category, methylation levels were higher in accompanying scrapes with abnormal cytology than in scrapes with normal cytology. Concluding, CADM1 and MAL promoter methylation levels in hrHPV-positive cervical scrapes are related to the degree and duration of underlying cervical disease and markedly increased in cervical cancer.
Keywords: DNA methylation; cervical scrapes, human papillomavirus; high-grade cervical intraepithelial neoplasia; tumour suppressor genes.
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