Methylation screening of the TGFBI promoter in human lung and prostate cancer by methylation-specific PCR

Jinesh N Shah,Genze Shao,Yongliang Zhao,Tom K Hei

doi:10.1186/1471-2407-8-284

Abstract

BackgroundHypermethylation of the TGFBI promoter has been shown to correlate with decreased expression of this gene in human tumor cell lines. In this study, we optimized a methylation-specific polymerase chain reaction (MSP) method and investigated the methylation status of the TGFBI promoter in human lung and prostate cancer specimens.MethodsMethylation-specific primers were designed based on the methylation profiles of the TGFBI promoter in human tumor cell lines, and MSP conditions were optimized for accurate and efficient amplification. Genomic DNA was isolated from lung tumors and prostatectomy tissues of prostate cancer patients, bisulfite-converted, and analyzed by MSP.ResultsAmong 50 lung cancer samples, 44.0% (22/50) harbored methylated CpG sites in the TGFBI promoter. An analysis correlating gene methylation status with clinicopathological cancer features revealed that dense methylation of the TGFBI promoter was associated with a metastatic phenotype, with 42.9% (6/14) of metastatic lung cancer samples demonstrating dense methylation vs. only 5.6% (2/36) of primary lung cancer samples (p < 0.05). Similar to these lung cancer results, 82.0% (41/50) of prostate cancer samples harbored methylated CpG sites in the TGFBI promoter, and dense methylation of the promoter was present in 38.9% (7/18) of prostate cancer samples with the feature of locoregional invasiveness vs. only 19.4% (6/31) of prostate cancer samples without locoregional invasiveness (p < 0.05). Furthermore, promoter hypermethylation correlated with highly reduced expression of the TGFBI gene in human lung and prostate tumor cell lines.ConclusionWe successfully optimized a MSP method for the precise and efficient screening of TGFBI promoter methylation status. Dense methylation of the TGFBI promoter correlated with the extent of TGFBI gene silencing in tumor cell lines and was related to invasiveness of prostate tumors and metastatic status of lung cancer tumors. Thus, TGFBI promoter methylation can be used as a potential prognostic marker for invasiveness and metastasis in prostate and lung cancer patients, respectively.

Highlights

Hypermethylation of the TGFBI promoter has been shown to correlate with decreased expression of this gene in human tumor cell lines
Dense methylation of the TGFBI promoter (i.e., 16 methylated CpG sites detected) was found to correlate with metastatic phenotype, with a significantly higher frequency of dense methylation in metastatic tumor samples (6/14, 42.9%) than in primary tumor samples (2/36, 5.6%) (p < 0.05) (Tables 2, 3). These results suggest a positive correlation between dense methylation of the TGFBI promoter and metastasis in human lung cancer
Our present results showed that 16.0% of lung cancer and 28.0% of prostate cancer samples had dense TGFBI promoter hypermethylation and that such dense methylation was associated with metastasis in lung cancer and invasiveness in prostate cancer, suggesting a potential prognostic value of TGFBI hypermethylation in lung and prostate cancer patients

Summary

Introduction

Hypermethylation of the TGFBI promoter has been shown to correlate with decreased expression of this gene in human tumor cell lines. Approximately 50% of patients have metastatic disease at the time of diagnosis, which contributes to a less than 15% overall survival rate [1]. The discovery of epigenetic biomarkers for cancer invasiveness and metastasis may help in the identification of patients at risk for more aggressive cancer disease courses. This would potentially help clinicians to devise effective intensified and/or novel therapeutic strategies to prevent or decrease the likelihood of tumor progression to invasiveness and metastasis in such high-risk patients

Methods

Results

Discussion

Conclusion