HDAC4 and HDAC6 sustain DNA double strand break repair and stem-like phenotype by promoting radioresistance in glioblastoma cells

• Published in: Cancer letters 2017-07, Vol.397, p.1-11
• Main Authors: Marampon, Francesco, Megiorni, Francesca, Camero, Simona, Crescioli, Clara, McDowell, Heather P, Sferra, Roberta, Vetuschi, Antonella, Pompili, Simona, Ventura, Luca, De Felice, Francesca, Tombolini, Vincenzo, Dominici, Carlo, Maggio, Roberto, Festuccia, Claudio, Gravina, Giovanni Luca
• Format: Article
• Language: English
• Subjects: Adult; Aged; Apoptosis; Apoptosis - radiation effects; Autophagy; Autophagy - radiation effects; Biotechnology; Brain cancer; Brain Neoplasms - enzymology; Brain Neoplasms - genetics; Brain Neoplasms - pathology; Brain Neoplasms - radiotherapy; Cancer therapies; Cell culture; Cell death; Cell Line, Tumor; Cell Proliferation - radiation effects; Cellular Senescence - radiation effects; Deoxyribonucleic acid; DNA; DNA Breaks, Double-Stranded; DNA methylation; DNA Repair - radiation effects; Dose-Response Relationship, Radiation; Epigenetics; Female; Gene expression; Glioblastoma; Glioblastoma - enzymology; Glioblastoma - genetics; Glioblastoma - pathology; Glioblastoma - radiotherapy; HDAC4; HDAC6; Hematology, Oncology and Palliative Medicine; Histone Deacetylase 6; Histone Deacetylases - genetics; Histone Deacetylases - metabolism; Humans; Kinases; Male; Middle Aged; Molecular machines; Mutation; Neoplastic Stem Cells - enzymology; Neoplastic Stem Cells - pathology; Neoplastic Stem Cells - radiation effects; p53 Protein; Phenotype; Plasmids; Protein expression; Proteins; Radiation therapy; Radiation Tolerance - genetics; Radioresistance; Radiotherapy; Repressor Proteins - genetics; Repressor Proteins - metabolism; RNA Interference; Rodents; Senescence; Signal Transduction - radiation effects; Stem cells; Time Factors; Transfection; Tumor Suppressor Protein p53 - genetics; Tumor Suppressor Protein p53 - metabolism; Tumors
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/j.canlet.2017.03.028

Abstract The role of histone deacetylase (HDAC) 4 and 6 in glioblastoma (GBM) radioresistance was investigated. We found that tumor samples from 31 GBM patients, who underwent temozolomide and radiotherapy combined treatment, showed HDAC4 and HDAC6 expression in 93.5% and 96.7% of cases, respectively. Retrospective clinical data analysis demonstrated that high-intensity HDAC4 and/or HDAC6 immunostaining was predictive of poor clinical outcome. In vitro experiments revealed that short hairpin RNA-mediated silencing of HDAC4 or HDAC6 radiosensitized U87MG and U251MG GBM cell lines by promoting DNA double-strand break (DSBs) accumulation and by affecting DSBs repair molecular machinery. We found that HDAC6 knock-down predisposes to radiation therapy-induced U251MG apoptosis- and U87MG autophagy-mediated cell death. HDAC4 silencing promoted radiation therapy-induced senescence, independently by the cellular context. Finally, we showed that p53WT expression contributed to the radiotherapy lethal effects and that HDAC4 or HDAC6 sustained GBM stem-like radioresistant phenotype. Altogether, these observations suggest that HDAC4 and HDAC6 are guardians of irradiation-induced DNA damages and stemness, thus promoting radioresistance, and may represent potential prognostic markers and therapeutic targets in GBM.