J Cancer 2020; 11(17):5106-5117. doi:10.7150/jca.45822 This issue

Research Paper

MST4 inhibits human hepatocellular carcinoma cell proliferation and induces cell cycle arrest via suppression of PI3K/AKT pathway

Wei-Chao Hao1,2*, Qiu-Ling Zhong1, Wen-Qian Pang1, Mei-Juan Dian1, Jing Li1,3, Liu-Xin Han4, Wen-Tao Zhao5, Xiao-Ling Zhang6, Sheng-Jun Xiao7, Dong Xiao1,2✉, Xiao-Lin Lin1✉, Jun-Shuang Jia1✉

1. Guangdong Provincial Key Laboratory of Cancer Immunotherapy Research and Guangzhou Key Laboratory of Tumor Immunology Research, Cancer Research Institute, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China.
2. Institute of Comparative Medicine & Laboratory Animal Center, Southern Medical University, Guangzhou 510515, China.
3. Radiotherapy Center, the First People's Hospital of Chenzhou, Chenzhou 423000, China.
4. The third people's hospital of Kunming, Kunming 650041, China.
5. Department of Medical Oncology, The Third Affiliated Hospital of Kunming Medical University (Tumour Hospital of Yunnan Province), Kunming 650118, China.
6. Department of Physiology, Faculty of Basic Medical Sciences, Guilin Medical University, Guilin 541004, China.
7. Department of Pathology, the Second Affiliated Hospital, Guilin Medical University, Guilin 541199, China.
*First authors.

This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). See http://ivyspring.com/terms for full terms and conditions.
Hao WC, Zhong QL, Pang WQ, Dian MJ, Li J, Han LX, Zhao WT, Zhang XL, Xiao SJ, Xiao D, Lin XL, Jia JS. MST4 inhibits human hepatocellular carcinoma cell proliferation and induces cell cycle arrest via suppression of PI3K/AKT pathway. J Cancer 2020; 11(17):5106-5117. doi:10.7150/jca.45822. Available from https://www.jcancer.org/v11p5106.htm

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Objective: MST4 has exhibited functions in regulating cell polarity, Golgi apparatus, cell migration, and cancer. Mechanistically, it affects the activity of p-ERK, Hippo-YAP pathway and autophagy. The aim of this study is to further examine the functions of MST4 in hepatocellular carcinoma (HCC) and the underlying mechanism.

Methods: The expression level of MST4 in HCC and noncancer adjacent liver tissues was determined by qRT-PCR and immunohistochemistry staining. Wild-type MST4 (MST4) and a dominant-negative mutant of MST4 (dnMST4) were overexpressed in HCC cell lines, respectively. CCK-8 assay, EdU incorporation assay, and soft agar assay were used to determine cell proliferation in vitro. The xenograft mouse model was employed to determine HCC cell growth in vivo. Cell cycle analysis was performed by PI staining and flow cytometry. The expression of key members in PI3K/AKT pathway was detected by Western blot analysis.

Results: In our study, we reported new evidence that MST4 was frequently down-regulated in HCC tissues. Gain-of-function and loss-of-function experiments demonstrated that MST4 negatively regulated in vitro HCC cell proliferation. Additionally, MST4 overexpression suppressed Bel-7404 cell tumor growth in nude mice. Further experiments revealed that the growth-inhibitory effect of MST4 overexpression was partly due to a G1-phase cell cycle arrest. Importantly, mechanistic investigations suggested that dnMST4 significantly elevated the phosphorylation levels of key members of PI3K/AKT pathway, and the selective PI3K inhibitor LY294002 can reverse the proliferation-promoting effect of dnMST4.

Conclusions: Overall, our results provide a new insight into the clinical significance, functions and molecular mechanism of MST4 in HCC, suggesting that MST4 might have a potential therapeutic value in the HCC clinical treatment.

Keywords: MST4, Hepatocellular carcinoma (HCC), Proliferation, Cell cycle, PI3K/AKT pathway