Deregulated Expression of SRC, LYN and CKB Kinases by DNA Methylation and Its Potential Role in Gastric Cancer Invasiveness and Metastasis.

Adriano Azevedo Mello,Mariana Ferreira Leal,Leticia Martins Lamarão,Juan Antonio Rey,Ana Paula Negreiros Nunes Alves,Rommel Rodriguez Burbano,Giovanny Rebouças Pinto,Paulo Pimentel Assumpção,Marília Cardoso Smith,Barbara Do Nascimento Borges,Raquel Carvalho Montenegro,Jose G Trevino

doi:10.1371/journal.pone.0140492

Abstract

Kinases are downstream modulators and effectors of several cellular signaling cascades and play key roles in the development of neoplastic disease. In this study, we aimed to evaluate SRC, LYN and CKB protein and mRNA expression, as well as their promoter methylation, in gastric cancer. We found elevated expression of SRC and LYN kinase mRNA and protein but decreased levels of CKB kinase, alterations that may have a role in the invasiveness and metastasis of gastric tumors. Expression of the three studied kinases was also associated with MYC oncogene expression, a possible biomarker for gastric cancer. To understand the mechanisms that regulate the expression of these genes, we evaluated the DNA promoter methylation of the three kinases. We found that reduced SRC and LYN methylation and increased CKB methylation was associated with gastric cancer. The reduced SRC and LYN methylation was associated with increased levels of mRNA and protein expression, suggesting that DNA methylation is involved in regulating the expression of these kinases. Conversely, reduced CKB methylation was observed in samples with reduced mRNA and protein expression, suggesting CKB expression was found to be only partly regulated by DNA methylation. Additionally, we found that alterations in the DNA methylation pattern of the three studied kinases were also associated with the gastric cancer onset, advanced gastric cancer, deeper tumor invasion and the presence of metastasis. Therefore, SRC, LYN and CKB expression or DNA methylation could be useful markers for predicting tumor progression and targeting in anti-cancer strategies.

Highlights

Gastric cancer (GC) is the fourth most frequent cancer type and the second highest cause of cancer mortality worldwide [1]
Kinase expression and methylation patterns were evaluated in 138 pairs of GC samples and their corresponding non-neoplastic gastric tissue samples obtained from patients who underwent gastrectomy in Northern Brazil
We evaluated the role of CKB and of two members of the SRC family of kinases, SRC and LYN

Summary

Introduction

Gastric cancer (GC) is the fourth most frequent cancer type and the second highest cause of cancer mortality worldwide [1]. A better understanding of the biology of the progression of this neoplasia is crucial to reducing the mortality rate with the development of novel patient management and therapeutic strategies. Phosphotransferases, known as kinases, are downstream modulators and effectors of several cellular signaling cascades and play key roles in the development of neoplastic disease [3]. We previously performed screening to identify kinase proteins expressed in GC using Capture Compound Mass Spectrometry [5, 6] (S1 File), and 22 kinase proteins, including SRC, LYN and CKB, were detected (S1 Table). These three kinases were selected for further investigations (S1 Fig)

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Conclusion