RESUMO
Glioblastoma multiforme, the most common type of malignant brain tumor as well as the most aggressive one, lacks an effective therapy. Glioblastoma presents overexpression of mesenchymal markers Snail, Slug, and N-Cadherin and of the autophagic marker p62. Glioblastoma cell lines also present increased autophagy, overexpression of mesenchymal markers, Shh pathway activation, and lack of primary cilia. In this study, we aimed to evaluate the role of HDAC6 in the pathogenesis of glioblastoma, as HDAC6 is the most overexpressed of all HDACs isoforms in this tumor. We treated glioblastoma cell lines with siHDAC6. HDAC6 silencing inhibited proliferation, migration, and clonogenicity of glioblastoma cell lines. They also reversed the mesenchymal phenotype, decreased autophagy, inhibited Shh pathway, and recovered the expression of primary cilia in glioblastoma cell lines. These results demonstrate that HDAC6 might be a good target for glioblastoma treatment.
RESUMO
Glioblastoma is the most malignant brain tumor and presents high resistance to chemotherapy and radiotherapy. Surgery, radiotherapy and chemotherapy with temozolomide are the only treatments against this tumor. New targeted therapies, including epigenetic modulators such as 3deazaneplanocin A (DZNep; an EZH2 inhibitor) and panobinostat (a histone deacetylase inhibitor) are being tested in vitro, together with temozolomide. The present study combined APR246 with DZNep, panobinostat and teomozolomide in order to explore the possibility of restoring p53 function in mutated cases of glioblastoma. Following the ChouTalalay method it was demonstrated that APR246 acts in an additive manner together with the other compounds, reducing clonogenicity and inducing apoptosis in glioblastoma cells independently of p53 status.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Glioblastoma/tratamento farmacológico , Quinuclidinas/farmacologia , Proteína Supressora de Tumor p53/metabolismo , Adenosina/análogos & derivados , Adenosina/farmacologia , Adenosina/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Apoptose/efeitos dos fármacos , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaio de Unidades Formadoras de Colônias , Ensaios de Seleção de Medicamentos Antitumorais , Sinergismo Farmacológico , Epigênese Genética/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Glioblastoma/genética , Glioblastoma/patologia , Humanos , Mutação , Panobinostat/farmacologia , Panobinostat/uso terapêutico , Quinuclidinas/uso terapêutico , Temozolomida/farmacologia , Temozolomida/uso terapêutico , Proteína Supressora de Tumor p53/genéticaRESUMO
Current treatment against glioblastoma consists of surgical resection followed by temozolomide, with or without combined radiotherapy. Glioblastoma frequently acquires resistance to chemotherapy and/or radiotherapy. Novel therapeutic approaches are thus required. The inhibition of enhancer of zeste homolog 2 (EZH2; a histone methylase) and histone deacetylases (HDACs) are possible epigenetic treatments. Temozolomide, 3deazaneplanocin A (DZNep; an EZH2 inhibitor) and panobinostat (an HDAC inhibitor) were tested in regular and temozolomideresistant glioblastoma cells to confirm whether the compounds could behave in a synergistic, additive or antagonistic manner. A total of six commercial cell lines, two temozolomideinduced resistant cell lines and two primary cultures derived from glioblastoma samples were used. Cell lines were exposed to single treatments of the drugs in addition to all possible two and threedrug combinations. Colony formation assays, synergistic assays and reverse transcriptionquantitative PCR analysis of apoptosisassociated genes were performed. The highest synergistic combination was DZNep + panobinostat. Triple treatment was also synergistic. Reduced clonogenicity and increased apoptosis were both induced. It was concluded that the therapeutic potential of the combination of these three drugs in glioblastoma was evident and should be further explored.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Apoptose , Biomarcadores Tumorais/metabolismo , Resistencia a Medicamentos Antineoplásicos , Sinergismo Farmacológico , Glioblastoma/patologia , Adenosina/administração & dosagem , Adenosina/análogos & derivados , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Glioblastoma/tratamento farmacológico , Glioblastoma/metabolismo , Humanos , Panobinostat/administração & dosagem , Temozolomida/administração & dosagem , Células Tumorais CultivadasRESUMO
Glioblastoma or grade IV astrocytoma is the most common and lethal form of glioma. Current glioblastoma treatment strategies use surgery followed by chemotherapy with temozolomide. Despite this, numerous glioblastoma cases develop resistance to temozolomide treatments, resulting in a poor prognosis for the patients. Novel approaches are being investigated, including the inhibition of histone deacetylase 6 (HDAC6), an enzyme that deacetylates αtubulin, and whose overexpression in glioblastoma is associated with the loss of primary cilia. The aim of the present study was to treat glioblastoma cells with a selective HDAC6 inhibitor, tubastatin A, to determine if the malignant phenotype may be reverted. The results demonstrated a notable increase in acetylated αtubulin levels in treated cells, which associated with downregulation of the sonic hedgehog pathway, and may hypothetically promote ciliogenesis in those cells. Treatment with tubastatin A also reduced glioblastoma clonogenicity and migration capacities, and accelerated temozolomideinduced apoptosis. Finally, HDAC6 inhibition decreased the expression of mesenchymal markers, contributing to reverse epithelialmesenchymal transition in glioblastoma cells.