S100A6 promotes proliferation and migration of HepG2 cells via increased ubiquitin-dependent degradation of p53

Dongqiang Song,Dongmin Shi,Beili Xu,Shuyu Li,Yu Cai

doi:10.1515/med-2020-0101

Dongqiang Song, Dongmin Shi + Show 3 more

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https://doi.org/10.1515/med-2020-0101

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Abstract

PurposeS100A6 protein (calcyclin), a small calcium-binding protein of the S100 family, is often upregulated in various types of cancers, including hepatocellular carcinoma (HCC). The aim of this study was to illustrate the molecular mechanism of S100A6 in regulating the proliferation and migration of HCC cells.MethodsThe expressions of S100A6 in human HCC and adjacent non-tumor liver specimens were detected using immunoblotting and quantitative PCR (qPCR). The recombinant glutathione S-transferase (GST)-tagged human S100A6 protein was purified and identified. After treatment with S100A6, the proliferation of HepG2 cells was detected by the MTT and colony formation assay, and the migration of HepG2 cells was investigated by the transwell migration assay; the protein levels of cyclin D1 (CCND1), E-cadherin, and vimentin were also tested by immunoblotting. The effect of S100A6 on p21 and nuclear factor-κB pathway was verified by performing the dual luciferase assay. Then, the expression of p21 and its transcription activator, p53, was examined using immunoblotting and qPCR, the ubiquitination of which was investigated through co-immunoprecipitation.ResultsIt was found that the level of S100A6 was higher in the HCC tissues than in the adjacent non-tumor liver specimens. Exogenous overexpression of S100A6 promoted the proliferation and migration of HepG2 cells. S100A6 was observed to regulate p21 mRNA and protein expression levels and decrease p53 protein expression level, not mRNA level, by promoting the ubiquitination of p53 via the proteasome-dependent degradation pathway.ConclusionOur study indicated that S100A6 overexpression could promote the proliferation and migration of HCC cells by enhancing p53 ubiquitin-dependent proteasome degradation, ultimately regulating the p21 expression level.

Highlights

Hepatocellular carcinoma (HCC) contributes to the fourth highest mortality rate of cancer in China, accounting for approximately 40% of the total cases and deaths [1]
We explored the expression of S100A6 in human HCC and adjacent non-tumor liver specimens and investigated the effect of S100A6 protein on the cell proliferation and migration of HepG2 cells, as well as its underlying mechanism involved with p21 and p53
The HCC cell lines presented a significant upregulation of S100A6 when compared with the normal liver cell lines (Figure 1c)

Summary

Introduction

Hepatocellular carcinoma (HCC) contributes to the fourth highest mortality rate of cancer in China, accounting for approximately 40% of the total cases and deaths [1]. Significant improvement has been made in HCC diagnosis and therapy in the past few decades, long-term clinical prognosis and mortality rate are still unsatisfactory [4]; it is imperative that new therapeutic targets merit investigation. This study focused on the pathogenic genes and molecular mechanisms involved in HCC. As indicated by the previous studies, S100A6 is associated with tumorigenesis and tumor progression, promoting the proliferation and migration of human colorectal cancer cells, HCC cells, and osteosarcoma cells and epithelial–mesenchymal transition (EMT) of pancreatic cancer cells [6,7,8,9,10]. S100A6 was found to be associated with the poor

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