TRAF6 function as a novel co-regulator of Wnt3a target genes in prostate cancer

Abstract

Background Tumour necrosis factor receptor associated factor 6 (TRAF6) promotes inflammation in response to various cytokines. Aberrant Wnt3a signals promotes cancer progression through accumulation of β-Catenin. Here we investigated a potential role for TRAF6 in Wnt signaling. Methods TRAF6 expression was silenced by siRNA in human prostate cancer (PC3U) and human colorectal SW480 cells and by CRISPR/Cas9 in zebrafish. Several biochemical methods and analyses of mutant phenotype in zebrafish were used to analyse the function of TRAF6 in Wnt signaling. Findings Wnt3a-treatment promoted binding of TRAF6 to the Wnt co-receptors LRP5/LRP6 in PC3U and LNCaP cells in vitro. TRAF6 positively regulated mRNA expression of β-Catenin and subsequent activation of Wnt target genes in PC3U cells. Wnt3a-induced invasion of PC3U and SW480 cells were significantly reduced when TRAF6 was silenced by siRNA. Database analysis revealed a correlation between TRAF6 mRNA and Wnt target genes in patients with prostate cancer, and high expression of LRP5, TRAF6 and c-Myc correlated with poor prognosis. By using CRISPR/Cas9 to silence TRAF6 in zebrafish, we confirm TRAF6 as a key molecule in Wnt3a signaling for expression of Wnt target genes. Interpretation We identify TRAF6 as an important component in Wnt3a signaling to promote activation of Wnt target genes, a finding important for understanding mechanisms driving prostate cancer progression. Fund KAW 2012.0090, CAN 2017/544, Swedish Medical Research Council (2016-02513), Prostatacancerförbundet, Konung Gustaf V:s Frimurarestiftelse and Cancerforskningsfonden Norrland. The funders did not play a role in manuscript design, data collection, data analysis, interpretation nor writing of the manuscript.

Lycorine targets multiple myeloma stem cell‐like cells by inhibition of Wnt/β‐catenin pathway

“…While our data showed that BMSCs upregulated the expression of β‐catenin in ARP1 cells (Fig 3B), treatment of the cells with lycorine caused a significant decrease of β‐catenin in the presence of BMSCs in a dose‐dependent manner (Fig 3C). Wnt3a ligand is a known activator of the canonical Wnt pathway (Aripaka et al ., 2019). Results showed that Wnt3a ligand accelerates the proliferation of ARP1 cells; however, lycorine diminished the pro‐proliferative effect of Wnt3a on ARP1 cells (Fig 3D).…”

TRAF6 Promotes Gastric Cancer Cell Self-Renewal, Proliferation, and Migration

“…TRAF6 has been reported to be a significant oncogene in pancreatic cancer [ 5 ], prostate cancer [ 6 ], and nasopharyngeal carcinoma [ 7 ]. Moreover, TRAF6 is targeted in multiple immune functions through regulation of MAPK and NF- κ B activation [ 11 – 13 ].…”

“…As an E3 ubiquitin ligase, TRAF6 may rely on ubiquitin to regulate tumorigenesis [ 4 ]. TRAF6 is a significant oncogene in pancreatic cancer [ 5 ], prostate cancer [ 6 ], and nasopharyngeal carcinoma [ 7 ]. In addition, TRAF6 activates NF- κ B signaling in RAS-driven lung cancers [ 8 ].…”

The relationship between TRAF6 and tumors

“…Most importantly, the components of the Wnt pathway are involved in EMT and cell adhesion, stem cell regeneration, and cell proliferation and apoptosis, and abnormalities in these molecules often lead to the development of many types of cancer [ 50 – 52 ]. As a key transfer adaptor protein that transduces the Wnt3a/β-Catenin pathway, TRAF6 upregulated the mRNA expression of β-Catenin and subsequently activated Wnt target genes such as c - Myc and LRP5 in human prostate cancer PC3U cells [ 53 ] (Fig. 3 ).…”