Connexin 30 expression inhibits growth of human malignant gliomas but protects them against radiation therapy.
Artesi, Maria ; ; et al
in Neuro-oncology (2014)
BACKGROUND: Glioblastomas remain ominous tumors that almost invariably escape treatment. Connexins are a family of transmembrane, gap junction-forming proteins, some members of which were reported to act ... [more ▼]
BACKGROUND: Glioblastomas remain ominous tumors that almost invariably escape treatment. Connexins are a family of transmembrane, gap junction-forming proteins, some members of which were reported to act as tumor suppressors and to modulate cellular metabolism in response to cytotoxic stress. METHODS: We analyzed the copy number and expression of the connexin (Cx)30 gene gap junction beta-6 (GJB6), as well as of its protein immunoreactivity in several public and proprietary repositories of glioblastomas, and their influence on patient survival. We evaluated the effect of the expression of this gap junction protein on the growth, DNA repair and energy metabolism, and treatment resistance of these tumors. RESULTS: The GJB6 gene was deleted in 25.8% of 751 analyzed tumors and mutated in 15.8% of 158 tumors. Cx30 immunoreactivity was absent in 28.9% of 145 tumors. Restoration of Cx30 expression in human glioblastoma cells reduced their growth in vitro and as xenografts in the striatum of immunodeficient mice. Cx30 immunoreactivity was, however, found to adversely affect survival in 2 independent retrospective cohorts of glioblastoma patients. Cx30 was found in clonogenic assays to protect glioblastoma cells against radiation-induced mortality and to decrease radiation-induced DNA damage. This radioprotection correlated with a heat shock protein 90-dependent mitochondrial translocation of Cx30 following radiation and an improved ATP production following this genotoxic stress. CONCLUSION: These results underline the complex relationship between potential tumor suppressors and treatment resistance in glioblastomas and single out GJB6/Cx30 as a potential biomarker and target for therapeutic intervention in these tumors. [less ▲]Detailed reference viewed: 18 (9 ULg)
Casein kinase 2 inhibition modulates the DNA damage response but fails to radiosensitize malignant glioma cells.
KROONEN, Jérôme ; Artesi, Maria ; CAPRARO, Valérie et al
in International Journal of Oncology (2012), 41(2), 776-82
Inhibitors of casein kinase 2 (CK2), a regulator of cell proliferation and mediator of the DNA damage response, are being evaluated in clinical trials for the treatment of cancers. Apigenin was capable of ... [more ▼]
Inhibitors of casein kinase 2 (CK2), a regulator of cell proliferation and mediator of the DNA damage response, are being evaluated in clinical trials for the treatment of cancers. Apigenin was capable of inhibiting the activation of CK2 following gamma irradiation in LN18 and U87 malignant glioma cells. Apigenin and siRNA-mediated CK2 protein depletion further inhibited NF-kappaB activation and altered the Tyr68 phosphorylation of Chk2 kinase, a DNA damage response checkpoint kinase, following irradiation. However, CK2 inhibition did not decrease the ability of these glioma cells to repair double-strand DNA breaks, as assessed by COMET assays and gamma-H2Ax staining. Likewise, apigenin and siRNA-induced depletion of CK2 failed to sensitize glioma cells to the cytotoxic effect of 2 to 10 G-rays of gamma irradiation, as assessed by clonogenic assays. These results contrast with those found in other cancer types, and urge to prudence regarding the inclusion of malignant glioma patients in clinical trials that assess the radiosensitizing role of CK2 inhibitors in solid cancers. [less ▲]Detailed reference viewed: 17 (7 ULg)
Early termination of ISRCTN45828668, a phase 1/2 prospective, randomized study of sulfasalazine for the treatment of progressing malignant gliomas in adults.
Robe, Pierre ; Martin, Didier ; Nguyen-Khac, Minh-Tuan et al
in BMC Cancer (2009), 9
BACKGROUND: Sulfasalazine, a NF-kappaB and x(c)-cystine/glutamate antiport inhibitor, has demonstrated a strong antitumoral potential in preclinical models of malignant gliomas. As it presents an ... [more ▼]
BACKGROUND: Sulfasalazine, a NF-kappaB and x(c)-cystine/glutamate antiport inhibitor, has demonstrated a strong antitumoral potential in preclinical models of malignant gliomas. As it presents an excellent safety profile, we initiated a phase 1/2 clinical study of this anti-inflammatory drug for the treatment of recurrent WHO grade 3 and 4 astrocytic gliomas in adults. METHODS: 10 patients with advanced recurrent anaplastic astrocytoma (n = 2) or glioblastoma (n = 8) aged 32-62 years were recruited prior to the planned interim analysis of the study. Subjects were randomly assigned to daily doses of 1.5, 3, 4.5, or 6 grams of oral sulfasalazine, and treated until clinical or radiological evidence of disease progression or the development of serious or unbearable side effects. Primary endpoints were the evaluation of toxicities according to the CTCAE v.3.0, and the observation of radiological tumor responses based on MacDonald criteria. RESULTS: No clinical response was observed. One tumor remained stable for 2 months with sulfasalazine treatment, at the lowest daily dose of the drug. The median progression-free survival was 32 days. Side effects were common, as all patients developed grade 1-3 adverse events (mean: 7.2/patient), four patients developed grade 4 toxicity. Two patients died while on treatment or shortly after its discontinuation. CONCLUSION: Although the proper influence of sulfasalazine treatment on patient outcome was difficult to ascertain in these debilitated patients with a large tumor burden (median KPS = 50), ISRCTN45828668 was terminated after its interim analysis. This study urges to exert cautiousness in future trials of Sulfasalazine for the treatment of malignant gliomas. TRIAL REGISTRATION: Current Controlled Trials ISRCTN45828668. [less ▲]Detailed reference viewed: 45 (13 ULg)