Silencing high mobility group protein B1 inhibits malignant biological behavior of glioblastoma cells

Abstract

Objective To investigate the effects of high expression of high mobility group protein B1 (HMGB1) on the invasion ability of glioblastoma (GBM) and the efficacy of temozolomide (TMZ) therapy. Methods The HMGB1 sequencing data of 319 GBM samples from TCGA database were gained for differential expression and survival analysis. Immunohistochemistry (IHC) was adopted to assess the expression of HMGB1 in 4 samples (3 glioma samples, with WHO grade Ⅱ, Ⅲ and Ⅳ, respectively, and 1 para-tumoral brain tissue as control) which were collected from our hospital's biobank (inpatients from May to October 2019, male, aged 40~88 years, median 58.5 years, being confirmed as glioma by histopathological examination after tissue resection, without radiotherapy or chemotherapy prior to surgery). Moreover, lentiviral vector was transfected to construct HMGB1 silenced GBM cell lines (U251 and LN229). Western blotting was performed to detect HMGB1 expression; CCK-8 and transwell assays were adopted to analyze the effect of HMGB1 on cell proliferation and invasion ability. Finally, the role of HMGB1 in TMZ therapy was evaluated by CCK-8 assay (TMZ powder was dissolved in dimethyl sulfoxide to prepare 100 mmol/L storage solution, and the final concentration used was 250, 500, 1 000 and 1 500 μmol/L, respectively). Results TCGA database showed that HMGB1 mRNA level was significantly upregulated in glioma tissue (P < 0.01), increasing with WHO grade, and was negatively correlated with the prognosis of patients (P < 0.01). HMGB1 silenced GBM cells had decreased proliferation (P < 0.05) and inhibited invasion ability (P < 0.01), and were more sensitive to TMZ therapy. Conclusion HMGB1 is remarkably up-regulated in GBM cells, and its high expression contributes to the enhanced invasion ability and temozolomide resistance of GBM cells.

Keywords

• glioblastoma
• high mobility group protein b1
• temozolomide
• drug resistance
• invasion