DSTYK Promotes Metastasis and Chemoresistance via EMT in Colorectal Cancer.

Jinyu Zhang,Yong Jiang,Philip H Howe,Ashlin E Thomas,Zachary Miller,Zhi Q Yao,Phillip R Musich,Qian Xie

doi:10.3389/fphar.2020.01250

Abstract

ObjectiveTumor metastasis and resistance to chemotherapy are two critical factors that contribute to the high death rate of colorectal cancer (CRC) patients. Metastasis is facilitated by the epithelial-mesenchymal transition (EMT) of tumor cells, which has emerged not only as a fundamental process during metastasis, but is also a key process leading to chemoresistance of cancer cells. However, the underlying mechanisms of EMT in CRC cell remain unknown. Here, we aim to assess the role of dual serine/threonine and tyrosine protein kinase (DSTYK) in CRC metastasis and chemoresistance.MethodsTo study the role of DSTYK in TGF-β-induced EMT, we employed techniques including Crispr/Cas9 knockout (KO) to generate DSTYK KO cell lines, RT-PCR to detect the mRNA expression, immunofluorescence analyses, and western blots to detect protein levels of DSTYK in the following 4 cell lines: control LS411N-TβRII and LS411N-TβRII/DSTYK KO, control LS513 and LS513/DSTYK KO cells, treated with/without TGF-β. The effects of DSTYK on apoptosis were investigated by MTT assays, flow cytometry assays, and TUNEL assays. The expression of DSTYK in CRC patients and its correlation with EMT markers were determined by bioinformatics analysis. For in vivo analysis, both xenograft and orthotopic tumor mouse models were employed to investigate the function of DSTYK in chemoresistance and metastasis of tumors.ResultsIn this study, we demonstrate that the novel kinase DSTYK promotes both TGF-β-induced EMT and the subsequent chemoresistance in CRC cells. DSTYK KO significantly attenuates TGF-β–induced EMT and chemoresistance in CRC cells. According to the Gene Expression Omnibus (GEO) database, the expression of DSTYK is not only positively correlated to the expression of TGF-β, but proportional to the death rate of CRC patients as well. Evidently, the expression of DSTYK in the metastatic colorectal cancer samples from patients was significantly higher than that of primary colorectal cancer samples. Further, we demonstrate in mouse models that chemotherapeutic drug treatment suppresses the growth of DSTYK KO tumors more effectively than control tumors.ConclusionOur findings identify DSTYK as a novel protein kinase in regulating TGF-β–mediated EMT and chemoresistance in CRC cells, which defines DSTYK as a potential therapeutic target for CRC therapy.

Highlights

Colorectal cancer (CRC) is the third leading cause of cancer death worldwide; the 5-year relative survival rate is only 53% to 65% in spite of many efforts to improve diagnosis and chemotherapy (Torre et al, 2015)
We found that DSTYK facilitates TGF-binduced epithelial–mesenchymal transition (EMT) and promotes chemoresistance in two CRC cell lines, LS411N-TGF-b receptor II (TbRII) and LS513, by inhibiting apoptosis
From our previous gene microarray analysis, we found that the expression of DSTYK is significantly higher in transforming growth factor-b (TGF-b)-induced EMT in CRC cells

Summary

Introduction

Colorectal cancer (CRC) is the third leading cause of cancer death worldwide; the 5-year relative survival rate is only 53% to 65% in spite of many efforts to improve diagnosis and chemotherapy (Torre et al, 2015). Tumor metastasis and resistance to chemotherapeutic treatment are considered as two critical factors that contribute to the death of CRC patients (Tsoumas et al, 2018). Preventing EMT will increase significantly the drug sensitivity of tumor cells and the survival rate of human CRC patients (Ren et al, 2013; Fischer et al, 2015; Zheng et al, 2015). The potential for improving chemotherapeutic efficacy in CRC patients critically depends on improving our understanding of the mechanism by which TGF-b induces EMT in CRC cells leading to chemoresistance and metastasis (Goldberg et al, 2004; Goldberg et al, 2006)

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Conclusion