TM4SF1 promotes EMT and cancer stemness via the Wnt/β-catenin/SOX2 pathway in colorectal cancer

Abstract

Background: Transmembrane 4 L six family member 1 (TM4SF1) is upregulated in several epithelial cancers and is closely associated with poor prognosis. However, the role of TM4SF1 and its potential mechanism in colorectal cancer (CRC) remain elusive.Methods: We investigated the expression of TM4SF1 in the Oncomine, the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and confirmed the results by immunohistochemistry (IHC), qPCR and Western blotting (WB) of CRC tissues. The effect of TM4SF1 on the epithelial-to-mesenchymal transition (EMT) and cancer stemness of CRC cells was investigated by Transwell, wound healing and sphere formation assays. A series of in vitro and in vivo experiments were conducted to reveal the mechanisms by which TM4SF1 modulates EMT and cancer stemness in CRC.Results: TM4SF1 expression was markedly higher in CRC tissues than in non-tumour tissues and was positively correlated with poor prognosis. Downregulation of TM4SF1 inhibited the migration, invasion and tumour sphere formation of SW480 and LoVo cells. Conversely, TM4SF1 overexpression significantly enhanced the migration, invasion and tumoursphere formation potential of CRC cells, Additionally, TM4SF1 silencing inhibited the EMT mediated by transforming growth factor-β1 (TGF-β1). Mechanistically, gene set enrichment analysis (GSEA) predicted that the Wnt signalling pathway was one of the most impaired pathways in TM4SF1-deficient CRC cells compared to controls. The results were further validated by WB, which revealed that TM4SF1 modulated SOX2 expression in a Wnt/β-catenin activation-dependent manner. Furthermore, we found that knockdown of TM4SF1 suppressed the expression of c-Myc, leading to decreased c-Myc binding to the SOX2 gene promoter. Finally, depletion of TM4SF1 inhibited metastasis and tumour growth in a xenograft mouse model.Conclusions: Our study substantiates a novel mechanism by which TM4SF1 maintains cancer cell stemness and EMT via the Wnt/β-catenin/c-Myc/SOX2 axis during the recurrence and metastasis of CRC.

Natural killer cell-related prognosis signature predicts immune response in colon cancer patients

“…Molecular pathways of TGF-β signaling are typical pathways that regulate tumorigenesis and tissue homeostasis and have been extensively studied in various biological processes. It has dual roles as a tumor suppressor in precancerous cells and a tumor promoter in cancer cells and has been shown to be involved in the development of various malignancies including CRC (Gachpazan et al, 2019;Tang et al, 2020). The results of Western blot showed that the expression and phosphorylation levels of key proteins in the TGF-β signaling pathway were significantly affected when SLC2A3 was knocked down.…”

Tumor cell stemness in gastrointestinal cancer: regulation and targeted therapy

“…Targeting multiple genes associated with GI tumors, it inhibits cell proliferation, reduces CSC stemness and suppresses EMT in HCC (Han et al, 2019), CRC (Huang et al, 2019a) and EC (Hu et al, 2020). Additionally, miR-30a and miR-9 downregulates TM4SF1 (Park et al, 2016;Park et al, 2017), a key oncogenic gene known for its role in activating the Wnt/ β-catenin pathway and enhancing EMT (Tang et al, 2020). MiRNAs also exert indirect regulatory effects via responding to TME alterations.…”