Theranostics 2019; 9(7):1909-1922. doi:10.7150/thno.30578

Research Paper

HMGB1-Induced p62 Overexpression Promotes Snail-Mediated Epithelial-Mesenchymal Transition in Glioblastoma Cells via the Degradation of GSK-3β

Hong Li1*, Junjie Li1*, Guozhong Zhang1,2,3*, Qian Da4*, Lei Chen1, Shishi Yu5, Qiang Zhou1, Zhijian Weng1, Zong Xin1, Linyong Shi1, Liyi Ma1, Annie Huang6, Songtao Qi1,2,3✉, Yuntao Lu1,2,3✉

1. Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China.
2. Nanfang Neurology Research Institution, Nanfang Hospital, Southern Medical University, Guangzhou, China.
3. Nanfang Glioma Center, Guangzhou, China
4. Department of Pathology, Ruijing Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
5. Editorial Department of the Journal of Southern Medical University, Guangzhou, China.
6. Brain Tumor Research Center, SickKids Hospital, Toronto, Canada.
*These authors contributed equally to this work.

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Citation:
Li H, Li J, Zhang G, Da Q, Chen L, Yu S, Zhou Q, Weng Z, Xin Z, Shi L, Ma L, Huang A, Qi S, Lu Y. HMGB1-Induced p62 Overexpression Promotes Snail-Mediated Epithelial-Mesenchymal Transition in Glioblastoma Cells via the Degradation of GSK-3β. Theranostics 2019; 9(7):1909-1922. doi:10.7150/thno.30578. Available from https://www.thno.org/v09p1909.htm

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Abstract

Rationale: Glioblastoma (GBM) is the most common and aggressive brain tumor, characterized by its propensity to invade the surrounding brain parenchyma. The effect of extracellular high-mobility group box 1 (HMGB1) protein on glioblastoma (GBM) progression is still controversial. p62 is overexpressed in glioma cells, and has been associated with the malignant features and poor prognosis of GBM patients. Hence, this study aimed to clarify the role of p62 in HMGB1-induced epithelial-mesenchymal transition (EMT) of GBM both in vitro and in vivo.

Methods: Immunoblotting, immunofluorescence and qRT-PCR were performed to evaluate EMT progression in both human GBM cell line and primary GBM cells. Transwell and wound healing assays were used to assess the invasion and migration of GBM cells. shRNA technique was used to investigate the role of p62 in HMGB1-induced EMT both in vitro and in vivo orthotopic tumor model. Co-immunoprecipitation assay was used to reveal the interaction between p62 and GSK-3β (glycogen synthase kinase 3 beta). Immunohistochemistry was performed to detect the expression levels of proteins in human GBM tissues.

Results: In this study, GBM cells treated with recombinant human HMGB1 (rhHMGB1) underwent spontaneous EMT through GSK-3β/Snail signaling pathway. In addition, our study revealed that rhHMGB1-induced EMT of GBM cells was accompanied by p62 overexpression, which was mediated by the activation of TLR4-p38-Nrf2 signaling pathway. Moreover, the results demonstrated that p62 knockdown impaired rhHMGB1-induced EMT both in vitro and in vivo. Subsequent mechanistic investigations showed that p62 served as a shuttling factor for the interaction of GSK-3β with proteasome, and ultimately activated GSK-3β/Snail signaling pathway by augmenting the degradation of GSK-3β. Furthermore, immunohistochemistry analysis revealed a significant inverse correlation between p62 and GSK-3β, and a combination of the both might serve as a more powerful predictor of poor survival in GBM patients.

Conclusions: This study suggests that p62 is an effector for HMGB1-induced EMT, and may represent a novel therapeutic target in GBM.

Keywords: HMGB1, p62, glioblastoma, GSK-3β, epithelial-to-mesenchymal transition (EMT)