Epigenetic regulation and anti-tumorigenic effects of SH2-containing protein tyrosine phosphatase 1 (SHP1) in human gastric cancer cells

Abstract

SH2-containing protein tyrosine phosphatase 1 (SHP1) is an important negative regulator in cytokine-mediated signal transduction and cell cycling. Recent studies have demonstrated that SHP1 promoter methylation is frequently observed in gastric adenocarcinoma tissues. In this in vitro study, we attempted to reveal promoter hypermethylation and to investigate effects of SHP1 in gastric carcinoma cell lines. We observed that both gene and protein expression of SHP1 were negative in 8 of 10 gastric cancer cell lines (SNU-1, SNU-5, SNU-16, SNU-638, SNU-719, MKN-28, MKN-45, AGS). Methylation-specific PCR (MSP) showed a methylation-specific band only in the 10 gastric cancer lines. Bisulfite pyrosequencing in AGS, MKN-28, and SNU-719 cells indicated that methylation frequency was as high as 94.4, 92.6, and 94.5 %, respectively, in the three cell lines. Treatment of SNU-719, MKN-28, and AGS cells with 5-Aza-2'-deoxycytidine (5-Aza-dc) led to re-expression of SHP1 in these cells. Introduction of exogenous SHP1 in SNU-719 and MKN-28 cells by transient transfection substantially downregulated protein expression of constitutive phosphor-Janus kinase 2 (JAK2) (tyrosine 1007/1008) and phosphor-signal transducers and activators of transcription 3 (STAT3) (tyrosine 705), which in turn decreased expression of STAT3 target genes including those encoding cyclin D1, MMP-9, VEGF-1, and survivin. Induction of SHP1 significantly inhibited cell proliferation, migration and invasion in SNU-719 and MKN-28 cells. Taken together, epigenetic silencing of SHP1 is frequently caused by promoter hypermethylation in gastric carcinoma cells. Overexpression of SHP1 downregulates the JAK2/STAT3 pathway to modulate various target genes and inhibit cell proliferation, migration, and invasion in gastric cancer cells.

Arsenic trioxide attenuates STAT-3 activity and epithelial-mesenchymal transition through induction of SHP-1 in gastric cancer cells

“…We previously reported that expression of SHP-1 is mostly attenuated or abolished in gastric cancer cell lines which are governed by epigenetic mechanism [ 8 ]. Sun et al showed that mRNA expression of SHP-1 is highest in normal gastric tissues, followed by intestinal metaplasia, dysplasia, and lowest in gastric cancer.…”

“…We previously reported that the protein and messenger RNA (mRNA) expression of SHP-1 is negative or minimal in various gastric cancer cell lines, which are mainly governed by CpG island promoter hypermethylation. Reinforced SHP-1 expression in gastric cancer cells effectively inhibits STAT3 activity and its target genes such as cyclin D1, matrix metalloproteinases-9 (MMP-9), vascular endothelial growth factor-1 (VEGF-1), and survivin [ 8 ]. Here, we report on the anti-EMT effect of ATO in gastric cancer cells by demonstrating dephosphorylation of JAK2/STAT3 and modulation of EMT markers including Snail1 and E-cadherin by ATO, and suggest that SHP-1 might be an important mediator for inactivation of the JAK2/STAT3 signaling pathway.…”

Inhibition of STAT3 in gastric cancer: role of pantoprazole as SHP-1 inducer

“…However, concerning the expression of SHP-1 in stomach tissue, data are very lacking. We have previously investigated promoter hypermethylation and gene expression of SHP-1 in most of gastric cancer cells and functional effects of SHP-1 on JAK2/STAT3 pathway [ 6 ]. Because protein or gene expression level of SHP-1 is very weak in most of stomach cancer tissues, SHP-1-induction strategy appears to be reasonable to effectively inhibit constitutive STAT3.…”

Oncogenic Tyrosine Phosphatases: Novel Therapeutic Targets for Melanoma Treatment

“…SHP-1 was initially classified as a tumor suppressor phosphatase [ 179 ] since its silencing, due to hypermethylation of CpG islands in the PTPN6 promoter region, is frequently associated with a poor prognosis and worse outcome in different types of cancers [ 180 , 181 , 182 , 183 , 184 , 185 , 186 , 187 , 188 , 189 ]. Indeed, several studies underlined that this enzyme controls cell cycle progression by impairing PDGF and insulin receptor signaling [ 190 , 191 ].…”