Journal Article

Epigenetic Silencing of TFPI-2 in Canine Diffuse Large B-Cell Lymphoma

Riondato, Fulvio, Bresolin, Silvia, Aricò, Arianna, Kronnie, Geertruy te, Marconato, Laura, Aresu, Luca, Ferraresso, Serena, Gelain, Maria Elena, Comazzi, Stefano, Bargelloni, Luca

2014

Overview

Epigenetic modifications are important early events during carcinogenesis. In particular, hypermethylation of CpG islands in the promoter region of tumor suppressor genes is a well-known mechanism of gene silencing that contributes to cancer development and progression. Tissue factor pathway inhibitor 2 (TFPI-2) is a tumor suppressor involved in invasiveness inhibition. Although TFPI-2 transcriptional silencing, through promoter hypermethylation, has been widely reported in several human malignancies, it has never been explored in lymphoma. In the present study TFPI-2 methylation and gene expression have been investigated in canine Diffuse Large B-cell lymphomas (cDLBCL). The methylation level of 23 CpGs located within the TFPI-2 promoter was investigated by bisulfite-specific PCR and next generation amplicon deep sequencing (GS Junior 454, Roche) in 22 cDLBCLs and 9 controls. For the same specimens, TFPI-2 gene expression was assessed by means of Real-time RT-PCR. Sequence analysis clearly demonstrated that TFPI2 is frequently hypermethylated in cDLBCL. Hypermethylation of the TFPI-2 promoter was found in 77% of DLBCLs (17 out of 22) and in one normal lymph node. Globally, dogs with DLBCL showed a mean methylation level significantly increased compared to controls (p<0.01) and analysis of hypermethylation by site identified 19 loci out of 23 (82%) with mean methylation levels from 2- to 120-fold higher in cDLBCL. Gene expression analysis confirmed a significant down-regulation of TFPI-2 (p<0.05) in DLBCLs compared with normal lymph nodes, suggesting that TFPI-2 hypermethylation negatively regulates its transcription. In addition, a significant positive correlation (p<0.01) was found between TFPI-2 methylation levels and age providing the first indication of age-associated epigenetic modifications in canine DLBCL. To conclude, our findings demonstrated that epigenetic dysregulation of TFPI-2, leading to its reduced expression, is frequently detected in canine DLBCL. In the next future, the aberrant TFPI-2 promoter hypermethylation may be considered in association with prognosis and therapy.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Aberration / Age / Analysis / Animals / B-cell lymphoma / Biology and life sciences / Bisulfite / Cancer / Carcinogenesis / Carcinogens / Complications and side effects / CpG islands / Deoxyribonucleic acid / Diagnosis / DNA / DNA Methylation / DNA, Neoplasm - metabolism / Dog Diseases - metabolism / Dog Diseases - pathology / Dogs / Epigenetics / Female / Food science / Gene expression / Gene Silencing / Genetic aspects / Genetic engineering / Genomes / Glycoproteins - biosynthesis / Health care / Humans / Invasiveness / Lymph nodes / Lymphatic system / Lymphocytes B / Lymphoma / Lymphoma, Large B-Cell, Diffuse - metabolism / Lymphoma, Large B-Cell, Diffuse - pathology / Lymphoma, Large B-Cell, Diffuse - veterinary / Male / Medical prognosis / Medicine and Health Sciences / Methylation / Neoplasm Proteins - biosynthesis / Non-Hodgkin's lymphomas / Pathogenesis / Patient outcomes / Polymerase chain reaction / Promoter Regions, Genetic / Risk factors / Tissue factor / Tumor suppressor genes