Galangin (GLN) Suppresses Proliferation, Migration, and Invasion of Human Glioblastoma Cells by Targeting Skp2-Induced Epithelial-Mesenchymal Transition (EMT)

Yu Xiong; Xue Lai; Wei Xiang; Jie Zhou; Jizhong Han; Hao Li; Huajiang Deng; Luotong Liu; Jianhua Peng; Ligang Chen

doi:10.2147/OTT.S264209

Galangin (GLN) Suppresses Proliferation, Migration, and Invasion of Human Glioblastoma Cells by Targeting Skp2-Induced Epithelial-Mesenchymal Transition (EMT)

Onco Targets Ther. 2020 Sep 17:13:9235-9244. doi: 10.2147/OTT.S264209. eCollection 2020.

Authors

Yu Xiong^#^{1

2

3}, Xue Lai^#⁴, Wei Xiang^{1

2

3}, Jie Zhou^{1

2

3}, Jizhong Han^{1

2

3}, Hao Li^{1

2

3}, Huajiang Deng^{1

2

3}, Luotong Liu^{1

2

3}, Jianhua Peng^{1

2

3}, Ligang Chen^{1

2

3}

Affiliations

¹ Department of Neurosurgery, Affiliated Hospital of Southwest Medical University, Southwest Medical University, Luzhou, 646000, People's Republic of China.
² Neurosurgery Clinical Medical Research Center of Sichuan Province, Luzhou 646000 People's Republic of China.
³ Academician (Expert) Workstation of Sichuan Province.
⁴ Day Surgery Center, Affiliated Hospital of Southwest Medical University, Luzhou 646000, People's Republic of China.

^# Contributed equally.

Abstract

Background: Galangin (GLN), a pure natural flavonoid compound found in plants, has been shown to exert anti-cancer effects against multiple cancer types, including glioma. However, its underlying molecular mechanism remains unclear. Epithelial-to-mesenchymal transition (EMT) performs an important function in the genesis and development of cancer. Skp2, a pivotal component of SCF^Skp2 E3 ubiquitin ligase, has been shown to function as an oncogene in GBM invasion that contributes to the EMT process. Thus, we explored whether GLN inhibited Skp2-mediated EMT and the mechanism underlying the Skp2 degradation pathway.

Methods: CCK-8 assay, wound healing assay and transwell assay were used to examine cell proliferation, migration, and invasion after treatment with or without GLN. RT-PCR and Western blotting analysis were performed to evaluate mRNA and protein expression, respectively. Co-immunoprecipitation was conducted to detect ubiquitinated Skp2 levels in vitro and in vivo after GLN treatment. Bioluminescence imaging was performed to examine the intracranial tumor size of U87 xenograft mice. Microscale thermophoresis (MST) experiment was used to detect interactions between Skp2 and GLN.

Results: GLN suppressed GBM cell growth, migration, and invasion, and also downregulated the expression of Skp2 and mesenchymal markers (Zeb1, N-cadherin, snail, vimentin) in vitro. Moreover, the overexpression of Skp2 in GBM cells decreased the effect of GLN on EMT. Furthermore, we demonstrated that GLN degraded skp2 protein through the ubiquitination proteasome pathway and directly interacted with skp2 protein, as shown through the MST assay.

Conclusion: This study is the first to identify Skp2 as a novel target of GLN for the treatment of GBM and report of Skp2 protein degradation in a ubiquitination proteasome pathway. Results from our study indicated the potential of GLN for the treatment of GBM through ubiquitin-mediated degradation of Skp2.

Keywords: EMT; GBM; Skp2; galangin; ubiquitination.

Grants and funding

This research was funded by the Project Program of Neurosurgical Clinical Research Center of Sichuan Province (Grant No.17082), the Project Program of Luzhou–Southwest Medical University (Grant No. 2018LZXNYD-ZK50) and Applied and Basic Research Program of the Science and Technology Department of Sichuan Province (Grant No. 2018JY0404).