DNA-methylation in anal intraepithelial lesions and anal squamous cell carcinoma

Purpose: Anal intraepithelial. neoplasia is associated with human papillomavirus infection and may progress to invasive squamous cell carcinoma (SCC), which is increasing in immunocompromised,patients. We hypothesize that anal intraepithelial neoplasia Js associated with abnor,,mal DNA methylation and that detection of these events may be used to improve screening programs. Experimental Design: Seventy-six patients were identified who underwent anal cytology screening and subsequent biopsy,at our institution between 1959 and. 2004. The specimens from these patients included 184 anal biopsies [normal, n 57; low-grade, squamous intraepithelial lesion (LSIL), n = 74; high-grade squamous intraepithelial lesion (HSIL), n = 41; and invasive SCC, n = 12] and 37 residual. liquid-based anal cytology specimens (normal, n = 11; LSIL,, n 12; HSIL, n = 14). The methylation status of the following genes was determined for each biopsy and cytology sample using real-time methylation-specific PCR: HIC1, RASSF1, RARB, CDKN2A, p14, TP73, APC, MLH1, MGMT DAPK1 and, IGSF4. Results: Methylation-specific PCR analysis of biopsy-samples revealed that DNA,methylation was more common in SCC and HSIL than LSIL and normal mucosa. Specifically, methylation of respectively) and HSIL (59% IGSF4 and DAPK1 was prevalent in SCC (75% and 75% of cas and 71%, respectively) but was absent in LSIL and normal biopsy samples. Methylation profiles of cytologic samples Were similar to those found in the biopsy samples. Conclusions: Aberrant DNA,methylation is a frequent event in anal HSIL and SCC. Methylation of IGSF4 and DAPK1 is Specific for HSL and SCC, and may serve as a useful molecular biomarker.