Guan Ming, Zhou Xiaoling, Soulitzis Nikolaos, Spandidos Demetrios A, Popescu Nicholas C
Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-4262, USA.
Clin Cancer Res. 2006 Mar 1;12(5):1412-9. doi: 10.1158/1078-0432.CCR-05-1906.
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.
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.
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.
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.
肝癌缺失基因1（DLC-1）编码一种具有肿瘤抑制功能的Rho GTP酶激活蛋白，该基因位于8号染色体p21-22区域，这是前列腺癌中经常缺失的一个区域。本研究旨在确定DLC-1在前列腺癌中是否失调，并评估DLC-1改变对前列腺癌发生的作用。
通过实时PCR、甲基化特异性PCR以及Southern和Western印迹法，对原发性前列腺癌、前列腺癌细胞系、良性前列腺增生和正常前列腺组织进行检测，以发现DLC-1基因的功能和结构改变。
在27例前列腺癌中的10例（37%）、5例前列腺癌细胞系中的3例（60%）以及21例良性前列腺增生中的5例（24%）中检测到DCL-1 mRNA表达下调或缺失。在27例前列腺癌中的13例（48%）以及2例匹配的正常组织中，在21例良性前列腺增生中的15例（71%）中发现了DLC-1启动子甲基化，但在10例非癌个体的正常前列腺组织中未发现。仅在3例前列腺癌和1例良性前列腺增生中发现了基因组缺失。在27例前列腺癌中的8例（30%）以及21例良性前列腺增生中的11例（52%）中未检测到DLC-1蛋白。DLC-1甲基化与前列腺癌患者的年龄相关（P = 0.006），与良性前列腺增生患者的前列腺特异性抗原血药浓度相关（P = 0.029）。用DNA甲基转移酶抑制剂或组蛋白脱乙酰酶抑制剂处理表达低水平DLC-1转录本的三种前列腺癌细胞系（PC-3、LNCaP和22Rv1）可增加DLC-1表达。
这些结果表明，DLC-1通过两种表观遗传机制发生转录沉默是常见的，可能参与前列腺癌和良性前列腺增生的发病机制，并且在前列腺癌的早期检测和基因治疗中可能具有潜在的临床应用价值。
