>> P-415: DNA Methylation Profiling Across the Spectrum of HPV-Associated Anal Squamous Neoplasia
19:00 PM - 19:00 PM
1Section of Colorectal Oncology, Gastrointestinal Oncology Program, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA; 2Risk Assessment, Detection and Intervention Program, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA; 3Department of Medicine, University of Washington, Seattle, WA, USA; 4Department of Bioinformatics, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA; 5Department of Pathology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA.
Introduction: There is growing evidence to suggest that changes in host genome DNA methylation patterns are among the critical molecular alterations associated with HPV-related carcinogenesis in squamous cell cancers (SCC) of the cervix and oropharynx. However, there is very little known about the epigenetic changes associated with the development of anal SCC. We sought to characterize HPV genotype and broad methylation profiles across the spectrum of anal squamous neoplasia.
Methods: Thirty-one formalin-fixed paraffin embedded samples from 25 patients were evaluated and included normal anal mucosa (NM; n=4), SCC-in situ (SCC-IS n=11) and invasive SCC (n=16). SFP10 LiPA HPV-typing system was used to determine the HPV status. Bisulfite-modified DNA was interrogated for methylation at 1,505 CpG loci representing 807 genes using the Illumina GoldenGate Methylation Assay.
Results: Our population was comprised of 13 women and 12 men with a median age of 48 years (range 26-81). Five patients were immunocompromised either by HIV or chemotherapy. All patients demonstrated infection with at least one high-risk HPV subtype, with HPV 16 noted in 15/16 patients with SCC. There was a trend towards increasing percentages of total CpG loci methylated with histologic progression; 56 ± 4% for NM, 61 ± 4% for SCC-IS and 63 ± 1% for SCC (p=NS). Fourteen gene loci were found to be significantly and differentially methylated (Kruskal-Wallis p<0.01) across the 3 groups, with nine genes associated with disease progression (Figure 1).
Conclusion: In HPV-associated anal neoplasms, we have identified a panel of methylated genes associated with the progression from anal NM to SCC. To our knowledge, this is the first reported application of broad high-throughput methylation analysis to anal neoplasia. Our findings have future implications for advances in the understanding of HPV-associated carcinogenesis as well as for anal SCC screening, diagnosis and treatment.