Inhibition of Casein kinase-2 induces p53-dependent cell cycle arrest and sensitizes glioblastoma cells to tumor necrosis factor (TNFα)-induced apoptosis through SIRT1 inhibition

Abstract

Glioblastoma multiforme (GBM) are resistant to TNFα-induced apoptosis and blockade of TNFα-induced NF-κB activation sensitizes glioma cells to apoptosis. As Casein kinase-2 (CK2) induces aberrant NF-κB activation and as we observed elevated CK2 levels in GBM tumors, we investigated the potential of CK2 inhibitors (CK2-Is) - DRB and Apigenin in sensitizing glioma cells to TNFα-induced apoptosis. CK2-Is and CK2 small interfering RNA (siRNA) reduced glioma cell viability, inhibited TNFα-mediated NF-κB activation, and sensitized cell to TNFα-induced apoptosis. Importantly, CK2-Is activated p53 function in wild-type but not in p53 mutant cells. Activation of p53 function involved its increased transcriptional activation, DNA-binding ability, increased expression of p53 target genes associated with cell cycle progression and apoptosis. Moreover, CK2-Is decreased telomerase activity and increased senescence in a p53-dependent manner. Apoptotic gene profiling indicated that CK2-Is differentially affect p53 and TNFα targets in p53 wild-type and mutant glioma cells. CK2-I decreased MDM2-p53 association and p53 ubiquitination to enhance p53 levels. Interestingly, CK2-Is downregulated SIRT1 activity and over-expression of SIRT1 decreased p53 transcriptional activity and rescued cells from CK2-I-induced apoptosis. This ability of CK2-Is to sensitize glioma to TNFα-induced death via multiple mechanisms involving abrogation of NF-κB activation, reactivation of wild-type p53 function and SIRT1 inhibition warrants investigation.

Molecular dynamics of the full-length p53 monomer

“…[127][128][129] The more ancient members of the family include p73, involved in cancer, 130 neurodevelopment, 131,132 and aging, 133 and p63, involved in epidermal development, 119,[134][135][136] cancer, [137][138][139][140][141] reproduction, 142 and heart development. 143 Understanding the structural restrain of its structure is pivotal to understand the function of p53 [144][145][146] as well as its potential therapeutic exploitation. 147,148 The regulation of p53 protein half-life is crucial to his function 149,150 and, consequently, for cancer progression.…”

Association of SIRT1 and HMGA1 expression in non-small cell lung cancer

“…HMGA1 also counteracts p53 transcriptional activity by relocalizing the nuclear p53 proapoptotic activator HIPK2 to the cytoplasm, thereby inhibiting the apoptotic function of p53 (32). SIRT1 is able to promote cell survival or inhibit apoptosis by deacetylating p53 (50,51). Deacetylation of the p53 protein promotes its accumulation during the stress response, and is required for p53-induced apoptosis and arrest of cell growth (52,53).…”

Constitutive activation of casein kinase 2 in glioblastomas: Absence of class restriction and broad therapeutic potential

“…CK2 has been reported to regulate tumor-initiating cell growth, tumor cell survival, DNA repair following ionizing radiation, and apoptosis in these tumors (4,5,7,8,(11)(12)(13). As a result, CK2 inhibition with drug inhibitors or siRNA technology was shown to alter the growth, survival and migration of glioma cell lines and slow down the growth of GBMs xenografts in immunodeficient mice (9,14).…”

“…CK2 has been reported to regulate tumor-initiating cell growth, tumor cell survival, DNA repair following ionizing radiation, and apoptosis in these tumors (4,5,7,8,(11)(12)(13). As a result, CK2 inhibition with drug inhibitors or siRNA technology was shown to alter the growth, survival and migration of glioma cell lines and slow down the growth of GBMs xenografts in immunodeficient mice (9,14).Prior to translating these findings to the bedside however, it remains unclear whether CK2 hyperactivity is restricted to classical GBMs presenting a CSNK2A1 amplification or not and/or whether all malignant glial tumors are evenly likely to benefit from CK2 inhibitory strategies.This report provides evidence that CK2 kinase hyperactivity occurs in vivo in all classes of GBMs as well as in glial tumors of lower grades and histology, and can be a target independently of Verhaak's classes and its TP53 status. However, additional factors, such as the NF-κB response to CK2 inhibition, may modulate the efficacy of this therapeutic strategy.…”