A quantitative promoter methylation profile of prostate cancer.
OBJECTIVE
Promoter hypermethylation is an alternative pathway for gene silencing in neoplastic cells and a promising cancer detection marker. Although quantitative methylation-specific PCR (QMSP) of the GSTP1 promoter has demonstrated near perfect specificity for cancer detection in prostate biopsies, we postulated that identification and characterization of additional methylation markers might further improve its high (80-90%) sensitivity.


METHODS
We surveyed nine gene promoters (GSTP1, MGMT, p14/ARF, p16/CDKN2A, RASSF1A, APC, TIMP3, S100A2, and CRBP1) by QMSP in tissue DNA from 118 prostate carcinomas, 38 paired high-grade prostatic intraepithelial neoplasias (HGPIN), and 30 benign prostatic hyperplasias (BPH). The methylation levels were calculated and were correlated with clinical and pathologic indicators.


RESULTS
Only the methylation frequencies of GSTP1 and APC were significantly higher in prostate carcinoma compared with BPH (P < 0.001). Methylation levels of GSTP1, APC, RASSF1A, and CRBP1, differed significantly between prostate carcinoma and HGPIN, and/or HGPIN or BPH (P < 0.0001). With QMSP and empirically defined cutoff values, the combined use of GSTP1 and APC demonstrated a theoretical sensitivity of 98.3% for prostate carcinoma, with 100% specificity. Methylation levels were found to correlate with tumor grade (GSTP1 and APC) and stage (GSTP1, RASSF1A, and APC).


CONCLUSIONS
Our data demonstrate the existence of a progressive increase of promoter methylation levels of several cancer-related genes in prostate carcinogenesis, providing additional markers to augment molecular detection of prostate carcinoma. Because methylation levels of GSTP1, APC, and RASSF1A are associated with advanced grade and stage, QMSP might augment the pathologic indicators currently used to predict tumor aggressiveness.
Jerónimo
Carmen
C
Department of Otolaryngology-Head and Neck Surgery, Head and Neck Cancer Research Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Henrique
Rui
R
Hoque
Mohammad O
MO
Mambo
Elizabeth
E
Ribeiro
Franclim R
FR
Varzim
Graça
G
Oliveira
Jorge
J
Teixeira
Manuel R
MR
Lopes
Carlos
C
Sidransky
David
D
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000368:Aged; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011401:Promoter Regions, Genetic; D011470:Prostatic Hyperplasia / Q000235:genetics / Q000378:metabolism; D019048:Prostatic Intraepithelial Neoplasia / Q000235:genetics / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism