np-031112 and Glioblastoma

Glioblastoma multiforme (GBM), a stage IV astrocytoma, is the most common brain malignancy among adults. Conventional treatments of surgical resection followed by radio and/or chemotherapy fail to completely eradicate the tumor. Resistance to the currently available therapies is mainly attributed to a subpopulation of cancer stem cells (CSCs) present within the tumor bulk that self-renew leading to tumor relapse with time. Therefore, identification of characteristic markers specific to these cells is crucial for the development of targeted therapies. Glycogen synthase kinase 3 (GSK-3), a serine-threonine kinase, is deregulated in a wide range of diseases, including cancer. In GBM, GSK-3β is overexpressed and its suppression in vitro has been shown to induce apoptosis of cancer cells.. In our study, we assessed the effect of GSK-3β inhibition with Tideglusib (TDG), an irreversible non-ATP competitive inhibitor, using two human GBM cell lines, U-251 MG and U-118 MG. In addition, we combined TDG with radiotherapy to assess whether this inhibition enhances the effect of standard treatment.. Our results showed that TDG significantly reduced cell proliferation, cell viability, and migration of both GBM cell lines in a dose- and time-dependent manner in vitro. Treatment with TDG alone and in combination with radiation significantly decreased the colony formation of U-251 MG cells and the sphere formation of both cell lines, by targeting and reducing their glioblastoma cancer stem-like cells (GSCs) population. Finally, cells treated with TDG showed an increased level of unrepaired radio-induced DNA damage and, thus, became sensitized toward radiation.. In conclusion, TDG has proven its effectiveness in targeting the cancerous properties of GBM in vitro and may, hence, serve as a potential adjuvant radio-therapeutic agent to better target this deadly tumor.

Topics: Antineoplastic Agents; Brain Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Chemoradiotherapy, Adjuvant; DNA Damage; Dose-Response Relationship, Drug; Glioblastoma; Glycogen Synthase Kinase 3 beta; Humans; Neoplastic Stem Cells; Thiadiazoles; Tumor Stem Cell Assay

Topics: Adult; Aged; Aged, 80 and over; Brain; Brain Neoplasms; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Female; Glioblastoma; Glycogen Synthase Kinase 3 beta; Hexanones; Humans; Intracellular Signaling Peptides and Proteins; Kaplan-Meier Estimate; Male; Middle Aged; Phosphorylation; Primary Cell Culture; Prognosis; Protein Stability; Pyridines; Pyrimidines; RNA, Small Interfering; Signal Transduction; Thiadiazoles; Xenograft Model Antitumor Assays

Emerging evidence has shown that GSK3β plays oncogenic roles in multiple tumour types; however, the underlying mechanisms remain largely unknown. Here, we show that nuclear GSK3β is responsible for the accumulation of the histone demethylase KDM1A and critically regulates histone H3K4 methylation during tumorigenesis. GSK3β phosphorylates KDM1A Ser683 upon priming phosphorylation of KDM1A Ser687 by CK1α. Phosphorylation of KDM1A induces its binding with and deubiquitylation by USP22, leading to KDM1A stabilization. GSK3β- and USP22-dependent KDM1A stabilization is required for the demethylation of histone H3K4, thereby repressing BMP2, CDKN1A and GATA6 transcription, which results in cancer stem cell self-renewal and glioblastoma tumorigenesis. In human glioblastoma specimens, KDM1A levels are correlated with nuclear GSK3β and USP22 levels. Furthermore, a GSK3 inhibitor, tideglusib, sensitizes tumour xenografts to chemotherapy in mice via KDM1A downregulation and improves survival. Our findings demonstrate that nuclear GSK3β- and USP22-mediated KDM1A stabilization is essential for glioblastoma tumorigenesis.

Topics: Animals; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Endopeptidases; Glioblastoma; Glycogen Synthase Kinase 3 beta; Histone Demethylases; Histones; Humans; Mice, Nude; Phosphorylation; Thiadiazoles; Thiolester Hydrolases; Ubiquitin Thiolesterase; Ubiquitination