DNA methylation in anal intraepithelial lesions and anal squamous cell carcinoma.
OBJECTIVE
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 is associated with abnormal DNA methylation and that detection of these events may be used to improve screening programs.


METHODS
Seventy-six patients were identified who underwent anal cytology screening and subsequent biopsy at our institution between 1999 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 IGSF4 and DAPK1 was prevalent in SCC (75% and 75% of cases, respectively) and HSIL (59% 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 HSIL and SCC, and may serve as a useful molecular biomarker.
Zhang
Jun
J
Department of Pathology and Laboratory Medicine, The Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA.
Martins
Ciro R
CR
Fansler
Zoya B
ZB
Roemer
Kristina L
KL
Kincaid
Erik A
EA
Gustafson
Karen S
KS
Heitjan
Daniel F
DF
Clark
Douglas P
DP
D048868:Adaptor Proteins, Signal Transducing; D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics; D000328:Adult; D001003:Anal Canal / Q000378:metabolism / Q000473:pathology*; D001005:Anus Neoplasms / Q000235:genetics / Q000473:pathology*; D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000473:pathology*; D002352:Carrier Proteins; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics; D051741:Kruppel-Like Transcription Factors; D008565:Membrane Proteins / Q000235:genetics; D000070957:MutL Protein Homolog 1; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D018168:Receptors, Retinoic Acid / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D025601:Adenomatous Polyposis Coli Protein; C403514:CADM1 protein, human; D002352:Carrier Proteins; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; C499808:HIC1 protein, human; D007136:Immunoglobulins; D051741:Kruppel-Like Transcription Factors; C501486:MLH1 protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C411762:RASSF1 protein, human; D018168:Receptors, Retinoic Acid; D014157:Transcription Factors; D025803:Tumor Suppressor Protein p14ARF; D025521:Tumor Suppressor Proteins; C082925:retinoic acid receptor beta; D019853:O(6)-Methylguanine-DNA Methyltransferase; D017346:Protein Serine-Threonine Kinases; D000070957:MutL Protein Homolog 1