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Aberrant Promoter Methylation of Laminin-5–Encoding Genes in Prostate Cancers and Its Relationship to Clinicopathological Features
Purpose: Laminin-5 (LN5) is an essential component of the basement membrane (BM) and is composed of three chains that are the products of three distinct genes ( LAMA3 , LAMB3 , and LAMC2 ). Differential expression of LN5 genes has been reported in prostate and other cancers. Recently, in lung cancer...
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Published in: | Clinical cancer research 2003-12, Vol.9 (17), p.6395-6400 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Purpose: Laminin-5 (LN5) is an essential component of the basement membrane (BM) and is composed of three chains that are the products
of three distinct genes ( LAMA3 , LAMB3 , and LAMC2 ). Differential expression of LN5 genes has been reported in prostate and other cancers. Recently, in lung cancers, we developed
methylation-specific PCR assays for each gene and demonstrated that the aberrant methylation as the mechanism of inactivation
of genes. In this study, we investigated the aberrant promoter methylation of LN5 genes in prostate cancers and correlated
the data with clinicopathological features.
Experimental Design: Promoter methylation of LN5-encoding genes was analyzed in 101 prostate cancer samples by methylation-specific PCR assay.
In addition, we analyzed 32 nonmalignant prostate tissue samples. The methylation index (MI) was determined as the methylated
fraction of the genes examined.
Results: The frequencies of loss of expression for the LAMA3 , LAMB3 , and LAMC2 genes in six prostate cancer cell lines were 83, 67, and 50%, respectively, whereas the methylation frequencies were 83,
67, and 33%, respectively. The concordances between loss of expression and methylation for the three genes were 100, 100,
and 83%, respectively. The frequency of methylation of LN5-encoding genes in prostate cancers and nonmalignant prostate tissues,
respectively, were: 44 and 12% for LAMA3 ( P = 0.001); 18 and 6% for LAMB3 ; and 41 and 9% for LAMC2 ( P = 0.001). In addition, methylation frequencies of any one or two genes, frequencies of at least one-gene methylation and
mean chain MI were significantly higher in prostate cancers than in nonmalignant prostate tissues. For clinicopathological
correlations, the high Gleason score (GS) group, high preoperative serum prostate-specific antigen (PSA) group, and high stage
group had significantly higher methylation frequencies of LAMA3 than their corresponding low groups. Methylation frequency of at least one gene and mean chain MI was significantly higher
in the high PSA group and high-stage group than their respective low groups. There was significant correlation between MI
and PSA. The high GS group had higher frequencies of at least one gene methylation and mean chain MI than the low GS group.
Conclusions: Our results demonstrate frequent epigenetic silencing of LN5-encoding genes in prostate cancers and it correlates with clinicopathological
features of poor prognosis. These findings are of biological interest and po |
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ISSN: | 1078-0432 1557-3265 |