Thrombospondin-4 is a putative tumour-suppressor gene in colorectal cancer that exhibits age-related methylation

Abstract

BackgroundThrombospondin-4 (THBS4) is a member of the extracellular calcium-binding protein family and is involved in cell adhesion and migration. The aim of this study was to evaluate the potential role of deregulation of THBS4 expression in colorectal carcinogenesis. Of particular interest was the possible silencing of expression by methylation of the CpG island in the gene promoter.MethodsFifty-five sporadic colorectal tumours stratified for the CpG Island Methylator Phenotype (CIMP) were studied. Immunohistochemical staining of THBS4 protein was assessed in normal and tumour specimens. Relative levels of THBS4 transcript expression in matched tumours and normal mucosa were also determined by quantitative RT-PCR. Colony forming ability was examined in 8 cell lines made to overexpress THBS4. Aberrant promoter hypermethylation was investigated as a possible mechanism of gene disruption using MethyLight. Methylation was also assessed in the normal colonic tissue of 99 patients, with samples biopsied from four regions along the length of the colon.ResultsTHBS4 expression was significantly lower in tumour tissue than in matched normal tissue. Immunohistochemical examination demonstrated that THBS4 protein was generally absent from normal epithelial cells and tumours, but was occasionally expressed at low levels in the cytoplasm towards the luminal surface in vesicular structures. Forced THBS4 over-expression caused a 50-60% repression of tumour colony growth in all eight cell lines examined compared to control cell lines. Tumours exhibited significantly higher levels of methylation than matched normal mucosa, and THBS4 methylation correlated with the CpG island methylator phenotype. There was a trend towards decreased gene expression in tumours exhibiting high THBS4 methylation, but the correlation was not significant. THBS4 methylation was detectable in normal mucosal biopsies where it correlated with increasing patient age and negatively with the occurrence of adenomas elsewhere in the colon.ConclusionsTHBS4 shows increased methylation in colorectal cancer, but this is not strongly associated with altered gene expression, either because methylation has not always reached a critical level or because other factors influence THBS4 expression. THBS4 may act as a tumour suppressor gene, demonstrated by its suppression of tumour colony formation in vitro. THBS4 methylation is detectable in normal colonic mucosa and its level may be a biomarker for the occurrence of adenomas and carcinoma.

FGFR2 Promotes Gastric Cancer Progression by Inhibiting the Expression of Thrombospondin4 via PI3K-Akt-Mtor Pathway

“…Some reports have shown TSP4 protein expression may facilitate invasion of tumor cells in breast cancer and hepatocellular carcinoma [12,25]. In contrast, another study reported that TSP4 may act as a tumor suppressor gene in colorectal cancer [26]. There are several possible reasons for the discrepancies between these findings: First, tumor progression is a dynamic, precisely regulated, multistep process, and TSP4 is an inducible marker that can be upregulatedor downregulated over time [27].…”

A Thrombospondin-Dependent Pathway for a Protective ER Stress Response

“…Once induced in select tissues, Thbs protein expression can be observed directly within cells or between cells in the extracellular space (Chen et al, 2000; Sodersten et al, 2007; Veliceasa et al, 2007; Greco et al, 2010). We observed prominent Thbs4 protein localization within the ER/SR compartment of adult cardiomyocytes of the heart, with some mild accumulation in the extracellular space or ECM.…”

“…We observed prominent Thbs4 protein localization within the ER/SR compartment of adult cardiomyocytes of the heart, with some mild accumulation in the extracellular space or ECM. Indeed, while Thbs’ are generally secreted, examples of their intracellular retention in the ER or vesicles have been reported (Chen et al, 2000; Sodersten et al, 2007; Veliceasa et al, 2007; Hauser et al, 1995; Greco et al, 2010). Thbs’ are assembled into trimers (Thbs1 and 2) or pentamers (Thbs3, 4, and 5) in the ER, and Thbs1 was shown to be part of a complex with PDI, BiP, p72 and Grp94, and to reside in the ER compartment for up to 30 minutes before presumably shuttling to the Golgi for gylcosylation (Prabakaran et al, 1996; Kuznetsov, 1997; Hecht et al, 2001).…”

Resveratrol inhibits IL‐6‐induced ovarian cancer cell migration through epigenetic up‐regulation of autophagy

“…FGF-BP increases tumorigenicity and is highly expressed in colon carcinoma [64] TGM2 (transglutaminase 2) Elevated expression is found in compact spheroid formation by ovarian cancer cells [65] C. Transcripts down-regulated by resveratrol and up-regulated by IL-6 EFNA1 (Ephrin A1) It binds to the Eph A2 tyrosine kinase receptor, which drives migration and invasion of colorectal cancers. Its mRNA expression correlates with poor prognosis in hepatocarcinoma and colorectal cancers [41,66,67] THBS4 (thrombospondin 4) It is a stromal protein involved in cellular migration, adhesion, and attachment that has been shown to play a role in metastatic progression of lung, breast, and colorectal cancers [68][69][70] SGK1 (serum and glucocorticoid regulated Kinase 1)…”