VSTM2A suppresses colorectal cancer and antagonizes Wnt signaling receptor LRP6

Abstract

Hyperactivation of Wnt/β-catenin signaling pathway is a critical step in colorectal tumorigenesis. In this study, we identified that V-set and transmembrane domain containing 2A (VSTM2A) was a top-downregulated secreted protein that negatively regulated Wnt singling pathways in colorectal cancer (CRC). We investigated the functional mechanisms and clinical implication of VSTM2A in CRC.Methods: Function of VSTM2A was investigated in vitro and in vivo. VSTM2A binding partner was identified by mass spectrometry, immunoprecipitation and Western blot. The clinical impact of VSTM2A was assessed in 355 CRC patients and TCGA cohort.Results: VSTM2A protein was prominently silenced in CRC tumor tissues and cell lines mediated by its promoter hypermethylation. VSTM2A DNA promoter hypermethylation and VSTM2A protein downregulation was associated with poor survival of CRC patients. Ectopic expression of VSTM2A inhibited colon cancer cell lines and organoid growth, induced CRC cells apoptosis, inhibited cell migration and invasion, and suppressed growth of xenograft tumors in nude mice. VSTM2A was released from CRC cells through a canonical secretion pathway. Secreted VSTM2A significantly suppressed Wnt signaling pathway in colon cancer cells. Wnt signaling co-receptor LDL receptor related protein 6 (LRP6) was identified as a cell membrane binding partner of VSTM2A. Using deletion/mutation and immunoprecipitation, we demonstrated that VSTM2A bound to LRP6 E1-4 domain with its IgV domain. VSTM2A suppressed LRP6 phosphorylation in a time and dose dependent manner, and induced LRP6 endocytosis and lysosome-mediated degradation, which collectively contributing to the inactivation of Wnt signaling.Conclusions: VSTM2A is a novel antagonist of canonical Wnt signaling by directly binding to LRP6 and induces LRP6 endocytosis and degradation. VSTM2A is a potential prognostic biomarker for the outcome of CRC patients.

<p>New Advances in Canonical Wnt/β-Catenin Signaling in Cancer</p>

“…In addition to inhibition of positive regulators for Wnt signaling, a negative regulator was also found as a possible target for Wnt signaling. 18 V-set and transmembrane domain containing 2A (VSTM2A) is a secreted protein that inhibits Wnt/β-catenin signaling in colon cancer by directly inhibiting LRP6 activity and inducing LRP6 endocytosis and degradation.…”

MicroRNA‑590 inhibits migration, invasion and epithelial‑to‑mesenchymal transition of esophageal squamous cell carcinoma by targeting low‑density lipoprotein receptor‑related protein 6

“…In addition, the Wnt signaling pathway can coordinate with or antagonize other signaling pathways to regulate the proliferation, migration, invasion and EMT of tumor cells (39,40). LRP6 is a key receptor protein in the Wnt signaling pathway (41), which may explain why LRP6 knockdown inhibited the migration, invasion and EMT of ESCC cells. In order to evaluate whether the changes caused by miR-590 were mediated by LRP6 in ESCC cells, biological analysis and luciferase experiments were performed, and LRP6 was identified as one of potential targets of miR-590.…”

Identification of a Five-Gene Prognostic Model and Its Potential Drug Repurposing in Colorectal Cancer Based on TCGA, GTEx and GEO Databases

“…In the present study, we found five hub genes (PGM2, PODXL, RHNO1, SCD, and SEPHS1) using WGCNA and Cox regression analysis. The five-gene signature model could efficiently stratify patient's overall survival and its efficacy was validated in the TCGA and the GSE17536 cohort, indicating a robust high prognostic value of the signature, especially when compared with the previous single biomarker (Dong et al, 2019 ; Jary et al, 2020 ). Moreover, other multigene-based models were mostly based on the differently expressed genes (DEGs) (Huang et al, 2020 ; Yang et al, 2020 ).…”

“…There is, therefore, currently an urgent need to identify more accurate prognostic models for CRC patients. However, previous studies have mostly focused on a single biomarker (Liu et al, 2018 ; Dong et al, 2019 ; Jary et al, 2020 ) or the results have been generated from small sample sizes (Huang et al, 2020 ; Yang et al, 2020 ) or have been based on DEGs (Huang et al, 2020 ; Yang et al, 2020 ), which might lower the performance of the prognostic biomarkers. In the present study, a five-gene signature was identified and validated based on the TCGA, GTEx, and GSE17536 cohort with a large sample seize ( Figure 1 ).…”