Tp53 Mutation Inhibits Ubiquitination and Degradation of WISP1 via Down-Regulation of Siah1 in Pancreatic Carcinogenesis.

Wei Wu,Lumin Wei,Tingting Bai,Mingping Xie,Yi Zang,Yuting Qian,Xu Liu,Juanjuan Li,Tong Li,Lifu Wang,Ying Zhu,Qi Wang

doi:10.3389/fphar.2018.00857

Abstract

Wnt1 inducible signaling pathway protein-1 (WISP1) may play an important role in promoting carcinogenesis. However, the biological function and underlying mechanism of WISP1 in pancreatic carcinogenesis still remains enigmatic. In this study, immunochemistry staining showed that protein levels of WISP1 were more significantly upregulated in pancreatic ductal adenocarcinoma (PDAC) tissues with Tp53 mutation than in PDAC tissues with Tp53 wild-type. In addition, a significant correlation was observed between increased malignant phenotype of tumors from well-differentiated adenocarcinoma tissues to moderately- or poorly-differentiated adenocarcinoma tissues shifting from cytoplasmic expression to nuclear accumulation of WISP1. Interestingly, WISP1 expression was correlated with the poor prognosis in PDAC patients with Tp53 mutation. Also, the biological function analysis showed that WISP1 may act as a potential oncogene in PDAC cells. In addition, immunofluorescence analysis showed that Tp53 mutation promoted WISP1 expression in PanIN and PDAC cells, while Siah E3 Ubiquitin Protein Ligase 1 (Siah1) inhibited WISP1 expression in PDAC cells. Moreover, through immunoprecipitation, immunoblotting analysis, in vitro binding assay, and ubiquitination assay, we found that Tp53 mutation inhibited ubiquitination and degradation of Siah1-dependent WISP1. Therefore, Tp53 mutation-Siah1-WISP1 is a new signaling pathway, playing an important role in pancreatic carcinogenesis.

Highlights

Pancreatic ductal adenocarcinoma is one of the most malignant tumors of the gastrointestinal tract and its incidence grows with the social and economic development levels
A significant correlation was observed between increased malignant phenotype of tumors from WD-pancreatic ductal adenocarcinoma (PDAC) to MD- or poorly-differentiated pancreatic ductal adenocarcinoma (PD-PDAC) and shift from cytoplasmic expression to nuclear accumulation of Wnt1 inducible signaling pathway protein-1 (WISP1)
The results showed that Siah E3 Ubiquitin Protein Ligase 1 (Siah1) staining was mainly focused on the cytoplasm in PDAC cells, and nuclear and cytoplasm WISP1 staining was sharply enhanced with silencing of Siah1 in Capan-2 cells (Figures 4A,B) (n = 3), nuclear and cytoplasm WISP1 staining was sharply downregulated with overexpression of Siah1 in Panc-1 cells (Figures 4C,D) (n = 3)

Summary

Introduction

Pancreatic ductal adenocarcinoma is one of the most malignant tumors of the gastrointestinal tract and its incidence grows with the social and economic development levels. In spite of continuous efforts on its early diagnosis and treatment, in the recent 5 years, the survival rate of pancreatic cancer still remains as low as 9% (Siegel et al, 2018). Wnt signaling pathway is highly conservative and its relevant mutations are universal among PDAC patients (Jones et al, 2008). Our previous study has showed a correlation between Tp53 mutation and WISP1 (Wang et al, 2015). Abnormal expression of WISP1 has been proven in various types of human malignancies (Gurbuz and Chiquet-Ehrismann, 2015; Chahal et al, 2016; Wu et al, 2016; Jing et al, 2017). A previous study demonstrated that WISP1 protects human lung and breast cancer cells from p53-dependent cell death, suggesting that there could be a crosstalk between Tp53 and WISP1 signaling pathways (Su et al, 2002).

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Conclusion