Tissue transglutaminase induces Epithelial-Mesenchymal-Transition and the acquisition of stem cell like characteristics in colorectal cancer cells.

Oluseyi Ayinde,Martin Griffin,Zhuo Wang

doi:10.18632/oncotarget.15370

Abstract

Human colon cancer cell lines (CRCs) RKO, SW480 and SW620 were investigated for TG2 involvement in tumour advancement and aggression. TG2 expression correlated with tumour advancement and expression of markers of epithelial-mesenchymal transition (EMT). The metastatic cell line SW620 showed high TG2 expression compared to the primary tumour cell lines SW480 and RKO and could form tumour spheroids under non- adherent conditions. TG2 manipulation in the CRCs by shRNA or TG2 transduction confirmed the relationship between TG2 and EMT. TGFβ1 expression in CRC cells, and its level in the cell medium and extracellular matrix was increased in primary tumour CRCs overexpressing TG2 and could regulate TG2 expression and EMT by both canonical (RKO) and non-canonical (RKO and SW480) signalling. TGFβ1 regulation was not observed in the metastatic SW620 cell line, but TG2 knockdown or inhibition in SW620 reversed EMT. In SW620, TG2 expression and EMT was associated with increased presence of nuclear β-catenin which could be mediated by association of TG2 with the Wnt signalling co-receptor LRP5. TG2 inhibition/knockdown increased interaction between β-catenin and ubiquitin shown by co-immunoprecipitation, suggesting that TG2 could be important in β-catenin regulation. β-Catenin and TG2 was also upregulated in SW620 spheroid cells enriched with cancer stem cell marker CD44 and TG2 inhibition/knockdown reduced the spheroid forming potential of SW620 cells. Our data suggests that TG2 could hold both prognostic and therapeutic significance in colon cancer.

Highlights

Colorectal cancer (CRC) is the third most common cancer in the world and a major cause of morbidity and mortality [1]
Using the well characterised human colorectal cancer cell lines RKO, SW480 and SW620 as a wellvalidated model [23] for the in vitro study of colorectal cancer progression we show that Tissue transglutaminase (TG2) expression correlates with disease progression
TG2 expression was determined in cell lysates of three well characterised colon cancer cell lines RKO, SW480 and SW620, via Western blotting

Summary

Introduction

Colorectal cancer (CRC) is the third most common cancer in the world and a major cause of morbidity and mortality [1]. Survival of the disease is highly dependent upon the stage of disease at diagnosis, and typically ranges from a 90% 5-year survival rate for cancers detected at the localized stage, 70% for regional, 10% for people diagnosed for distant metastatic cancer [3]. Metastasis plays a critical role in the poor prognosis, and more than one-third of patients with CRC will develop metastatic disease [4]. Epithelial-MesenchymalTransition (EMT) is a physiological process found in embryonic development, tissue remodelling and wound healing [5]. In neoplasms it is a critical step in the progression of tumour cells from in situ carcinoma to distant metastasis. Recent reports suggest that EMT results in the acquisition of other properties involved in carcinoma progression, such as increased resistance www.impactjournals.com/oncotarget to apoptosis, drug resistance, increased motility and the acquisition of stem cell-like properties [6]

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