Methylation pattern analysis in prostate cancer tissue: identification of biomarkers using an MS-MLPA approach.

Giorgia Gurioli,Daniele Calistri,Giacomo Cicchetti,Samanta Salvi,Ugo De Giorgi,Persio Dello Sbarba,Filippo Martignano,Valentina Casadio,Flavia Foca,Matteo Costantini,Roberta Gunelli

doi:10.1186/s12967-016-1014-6

Abstract

BackgroundEpigenetic silencing mediated by CpG island methylation is a common feature of many cancers. Characterizing aberrant DNA methylation changes associated with prostate carcinogenesis could potentially identify a tumour-specific methylation pattern, facilitating the early diagnosis of prostate cancer. The objective of the study was to assess the methylation status of 40 tumour suppressor genes in prostate cancer and healthy prostatic tissues.MethodsWe used methylation specific-multiplex ligation probe amplification (MS-MLPA) assay in two independent case series (training and validation set). The training set comprised samples of prostate cancer tissue (n = 40), healthy prostatic tissue adjacent to the tumor (n = 26), and healthy non prostatic tissue (n = 23), for a total of 89 DNA samples; the validation set was composed of 40 prostate cancer tissue samples and their adjacent healthy prostatic tissue, for a total of 80 DNA samples. Methylation specific-polymerase chain reaction (MSP) was used to confirm the results obtained in the validation set.ResultsWe identified five highly methylated genes in prostate cancer: GSTP1, RARB, RASSF1, SCGB3A1, CCND2 (P < 0.0001), with an area under the ROC curve varying between 0.89 (95 % CI 0.82–0.97) and 0.95 (95 % CI 0.90–1.00). Diagnostic accuracy ranged from 80 % (95 % CI 70–88) to 90 % (95 % CI 81–96). Moreover, a concordance rate ranging from 83 % (95 % CI 72–90) to 89 % (95 % CI 80–95) was observed between MS-MLPA and MSP.ConclusionsOur preliminary results highlighted that hypermethylation of GSTP1, RARB, RASSF1, SCGB3A1 and CCND2 was highly tumour-specific in prostate cancer tissue.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-1014-6) contains supplementary material, which is available to authorized users.

Highlights

Epigenetic silencing mediated by CpG island methylation is a common feature of many cancers
It is well known that epigenetic modifications such as DNA methylation in CpG islands are correlated with cancer development, indicating that such events could represent early phenomena of carcinogenesis [7]
The sensitivity of the MSMLPA technique was evaluated by constructing a curve based on the generation of different proportions (5, 10, 20, 40, 80, 100 %) of DNA derived from a prostate cancer cell line (LNCaP) with known methylation of GSTP1, RASSF1, SCGB3A1, CASP8, RARB, CD44, APC, RUNX3, CCND2, spiked in genomic DNA from a blood sample of a healthy donor

Summary

Introduction

Epigenetic silencing mediated by CpG island methylation is a common feature of many cancers. Characterizing aberrant DNA methylation changes associated with prostate carcinogenesis could potentially identify a tumour-specific methylation pattern, facilitating the early diagnosis of prostate cancer. The objective of the study was to assess the methylation status of 40 tumour suppressor genes in prostate cancer and healthy prostatic tissues. It is well known that epigenetic modifications such as DNA methylation in CpG islands are correlated with cancer development, indicating that such events could represent early phenomena of carcinogenesis [7]. For this reason, DNA methylation could be a potential biomarker for the early diagnosis of PCa. Tumour suppressor genes. Several studies have focused on the relationship between modifications of epigenetic mechanisms and prostate carcinogenesis [10]

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