Aberrant methylation and deacetylation of deleted in liver cancer-1 gene in prostate cancer: potential clinical applications.
OBJECTIVE
The deleted in liver cancer-1 (DLC-1) gene that encodes a Rho GTPase-activating protein with tumor suppressor function is located on chromosome 8p21-22, a region frequently deleted in prostate carcinomas. This study was designed to determine whether DLC-1 is deregulated in prostate carcinomas and to assess the contribution of DLC-1 alterations to prostate carcinogenesis.


METHODS
Primary prostate carcinomas, prostate carcinoma cell lines, benign prostatic hyperplasias, and normal prostatic tissues were examined for detection of functional and structural alterations of the DLC-1 gene by real-time PCR, methylation-specific PCR, and Southern and Western blots.


RESULTS
Down-regulation or loss of DCL-1 mRNA expression was detected in 10 of 27 (37%) prostate carcinomas, 3 of 5 (60%) prostate carcinoma cell lines, and 5 of 21 (24%) benign prostatic hyperplasias. DLC-1 promoter methylation was identified in 13 of 27 (48%) prostate carcinomas and 2 matching normal tissues and in 15 of 21 (71%) benign prostatic hyperplasias but was absent in 10 normal prostatic tissues from noncancerous individuals. Genomic deletions were found in only 3 prostate carcinomas and 1 benign prostatic hyperplasia. DLC-1 protein was not detected in 8 of 27 (30%) prostate carcinomas and 11 of 21 (52%) benign prostatic hyperplasias. Methylation of DLC-1 correlated with age in prostate carcinoma patients (P = 0.006) and with prostate-specific antigen blood levels in benign prostatic hyperplasia patients (P = 0.029). Treatment of the three prostate carcinoma cell lines (PC-3, LNCaP, and 22Rv1) expressing a low level of DLC-1 transcripts with inhibitors of DNA methyltransferase or histone deacetylase increased DLC-1 expression.


CONCLUSIONS
These results show that the transcriptional silencing of DLC-1 by two epigenetic mechanisms is common and may be involved in the pathogenesis of prostate carcinomas and benign prostatic hyperplasias and could have potential clinical application in the early detection and gene therapy of prostate cancer.
Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-4262, USA.
Ming
M
Guan
Xiaoling
X
Zhou
Nikolaos
N
Soulitzis
Demetrios A
DA
Spandidos
Nicholas C
NC
Popescu
D000107:Acetylation; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D000077209:Decitabine; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020690:GTPase-Activating Proteins; D017353:Gene Deletion; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D011467:Prostate / Q000378:metabolism; D011470:Prostatic Hyperplasia / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
C112352:DLC1 protein, human; D004791:Enzyme Inhibitors; D020690:GTPase-Activating Proteins; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; D000077209:Decitabine; D001374:Azacitidine