RHBDD1 promotes colorectal cancer metastasis through the Wnt signaling pathway and its downstream target ZEB1

Mengmeng Zhang,Xiaojuan Wang,Yalan Lu,Wei Song,Tao Jiao,Hong Zhao,Linfang Wang,Hongge Ju,Wenjie Liu,Shiying Miao,Rong Huang,Fei Miao,Han Wang,Fan Wu,Yuechao Zhao

doi:10.1186/s13046-018-0687-5

Abstract

Background40–50% of colorectal cancer (CRC) patients develop metastatic disease; the presence of metastasis hinders the effective treatment of cancer through surgery, chemotherapy and radiotherapy, which makes 5-year survival rate extremely low; therefore, studying CRC metastasis is crucial for disease therapy. In the present study, we investigated the role of rhomboid domain containing 1 (RHBDD1) in tumor metastasis of CRC.MethodsThe expression of RHBDD1 was analyzed in 539 colorectal tumor tissues for its correlation with lymphatic metastasis and distal metastasis. Transwell assay in vitro and pleural metastasis analysis in vivo were performed to determine the functions of RHBDD1 during CRC cells metastasis. RNA-seq analysis, TOP/FOP flash reporter assay, western blot and transwell assay were performed to investigate the underlying mechanism for the function of RHBDD1 on Wnt signaling pathway. Bioinformatics analysis was conducted to investigate epithelial-mesenchymal transition (EMT) and stemness in HCT-116 cells. Tissue microarray analysis, Q-PCR and western blot were performed to determine the correlation of RHBDD1 and Zinc Finger E-Box Binding Homeobox 1 (ZEB1).ResultsIn this study, we found that RHBDD1 expression was positively correlated with lymphatic metastasis and distal metastasis in 539 colorectal tumor tissues. RHBDD1 expression can promote CRC cells metastasis in vitro and in vivo. RNA-Seq analysis showed that the Wnt signaling pathway played a key role in this metastatic regulation. RHBDD1 mainly regulated ser552 and ser675 phosphorylation of β-catenin to activate the Wnt signaling pathway. Rescuing ser552 and ser675 phosphorylation of β-catenin resulted in the recovery of signaling pathway activity, migration, and invasion in CRC cells. RHBDD1 promoted EMT and a stem-like phenotype of CRC cells. RHBDD1 regulated the Wnt/β-catenin target gene ZEB1, a potent EMT activator, at the RNA and protein levels. Clinically, RHBDD1 expression was positively correlated with ZEB1 at the protein level in 71 colon tumor tissues.ConclusionsOur findings therefore indicated that RHBDD1 can promote CRC metastasis through the Wnt signaling pathway and ZEB1. RHBDD1 may become a new therapeutic target or clinical biomarker for metastatic CRC.

Highlights

Cancer metastasis accounts for 90% of deaths among tumor patients [1]
rhomboid domain containing 1 (RHBDD1) expression correlates with Colorectal cancer (CRC) metastasis A previous study by our group performed a tissue microarray analysis of 539 colorectal tumor tissues [16]
Positive correlation between RHBDD1 and Zinc Finger E-Box Binding Homeobox 1 (ZEB1) from CRC cells to tumor tissues from patients We already proved that RHBDD1 can influence gene signatures downstream of the Wnt signaling pathway; we further explored the exact target gene of the Wnt signaling pathway that is regulated by RHBDD1

Summary

Introduction

Cancer metastasis accounts for 90% of deaths among tumor patients [1]. The presence of metastasis at diagnosis or metastatic recurrence hinders the effective treatment of cancer, making these patients unsuited for chemotherapy and radiotherapy. 90% of CRC patients have aberrant Wnt signaling [5]. Wnt target genes such as SNAI1 [6, 7], ZEB1 [8] and Twist [9] are master inducers of the epithelialmesenchymal transition (EMT) program. The Wnt signaling pathway can regulate adult intestinal stem cells (ISCs) homeostasis, and aberrant activation induces the development of CRC stem cells [11]. The properties of cancer stem cells, including plasticity and better adaptation to the microenvironment, promote CRC metastasis [12]

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Discussion

Conclusion