Panobinostat potentiates temozolomide effects and reverses epithelial-mesenchymal transition in glioblastoma cells

Glioblastoma is the most common form of glioma, as well as the most aggressive. Patients suffering from this disease have a very poor prognosis. Surgery, radiotherapy, and temozolomide are the only approved treatments nowadays. Panobinostat is a pan-inhibitor of histone deacetylases (HDACs) that has been shown to break some pathways which play an important role in cancer development. A global intention of using panobinostat as a therapeutic agent against glioblastoma is beginning to be a reality. We have treated the LN405 glioblastoma cell line with temozolomide, panobinostat, and combined treatment, in order to test apoptosis, colony formation, and a possible molecular reversion of the mesenchymal phenotype of the cells to an epithelial one. Our results show that panobinostat decreased N-cadherin levels in the LN405 glioblastoma cell line while it increased the expression of E-cadherin, which might be associated with a mesenchymal–epithelial transition in glioblastoma cells. Colony formation was reduced, and apoptosis was increased with treatments. Our research highlights the importance of panobinostat as a potential adjuvant therapy to be used with temozolomide to treat glioblastoma and the advantages of the combined treatment versus temozolomide alone, which is currently the first-line treatment used to treat this tumo

Silencing of Histone Deacetylase 6 Decreases Cellular Malignancy and Contributes to Primary Cilium Restoration, Epithelial-to-Mesenchymal Transition Reversion, and Autophagy Inhibition in Glioblastoma Cell Lines

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

El papel de la histona desacetilasa 6 en el desarrollo del gioblastoma

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 an increased autophagic flux, overexpression of mesenchymal markers, Shh pathway activation and lack of primary cilia. In this study, we aimed to evaluate the role of histone deacetylase 6 (HDAC6) in the development of glioblastoma, as HDAC6 is the most overexpressed of all HDACs isoforms in this tumor. We treated glioblastoma cell lines with siHDAC6 and tubastatin A, a HDAC6 inhibitor. Both treatments inhibited proliferation, migration and clonogenicity of glioblastoma cell lines. They also reversed the mesenchymal phenotype, decreased the autophagic flux, inhibited Shh pathway and recovered the expression of primary cilia in glioblastoma cell lines. The treatment of tubastatin A also sensitized glioblastoma cell lines to temozolomide treatment, the chemotherapeutic agent used against glioblastoma. These results demonstrate that HDAC6 might be a good target for glioblastoma treatment

Panobinostat Potentiates Temozolomide Effects and Reverses Epithelial–Mesenchymal Transition in Glioblastoma Cells

Glioblastoma is the most common form of glioma, as well as the most aggressive. Patients suffering from this disease have a very poor prognosis. Surgery, radiotherapy, and temozolomide are the only approved treatments nowadays. Panobinostat is a pan-inhibitor of histone deacetylases (HDACs) that has been shown to break some pathways which play an important role in cancer development. A global intention of using panobinostat as a therapeutic agent against glioblastoma is beginning to be a reality. We have treated the LN405 glioblastoma cell line with temozolomide, panobinostat, and combined treatment, in order to test apoptosis, colony formation, and a possible molecular reversion of the mesenchymal phenotype of the cells to an epithelial one. Our results show that panobinostat decreased N-cadherin levels in the LN405 glioblastoma cell line while it increased the expression of E-cadherin, which might be associated with a mesenchymal–epithelial transition in glioblastoma cells. Colony formation was reduced, and apoptosis was increased with treatments. Our research highlights the importance of panobinostat as a potential adjuvant therapy to be used with temozolomide to treat glioblastoma and the advantages of the combined treatment versus temozolomide alone, which is currently the first-line treatment used to treat this tumor

In vitro therapy against glioblastoma cells by 3-Dezaneplanocin-A, panobinostat, and temozolomide

Background: Glioblastoma multiforme (GBM) is the most malignant primary brain tumor. Current treatment against this tumor consists of maximal surgical resection without threatening the patient's life, followed by a treatment with temozolomide, with or without combined radiotherapy. GBM is resistant to the conventional antitumor therapies, so in this research, we tried to inhibit tumor growth with the combination of three drugs: (1) panobinostat, an inhibitor of histone deacetylases, (2) 3-Dezaneplanocin-A (DZNep), an inhibitor of EZH2, a protein which belongs to the polycomb repressor complex 2, acting as a histone methylase, and (3) temozolomide, an alkylating agent. Methods: The T98G GBM commercial cell line was used. Cells were exposed to single treatments of the drugs and to the three possible combinations among them. Soon after, two-dimensional (2D) and 3D clonogenic assays were assessed for in vitro tumorigenicity testing. Real-time quantitative polymerase chain reaction of 2 proapoptotic genes (BAX and NOXA) and 2 antiapoptotic genes (BCL2 and BCL-XL) was also assessed. Results: The panobinostat and temozolomide combination produced a positive effect against T98G glioblastoma cells by reducing soft agar colony formation, by inducing high expression levels of NOXA, and by reducing BCL-XL expression. Equally, the panobinostat and DZNep combination produced a positive effect against T98G glioblastoma cells by reducing colony formation in adherent conditions and by inducing high expression levels of BAX. Finally, temozolomide alone was the most efficient drug for decreasing BCL2 expression. Conclusion: Panobinostat and temozolomide combination or panobinostat and DZNep combination might be more efficient against glioblastoma cells than just temozolomide

Inhibition of histone deacetylase 6 by tubastatin A as an experimental therapeutic strategy against glioblastoma

Background and Aim: Glioblastoma is the most lethal brain tumor. No effective curative treatment is available yet, and it is treated by surgery, temozolomide (TMZ), and radiotherapy, with an average overall survival of around 15 months. Inhibitors of histone deacetylases (HDACs) are being explored against a variety of tumors, including glioblastoma. Specific inhibitors of HDAC6, such as tubastatin A (Tub A), may potentially be beneficial as HDAC6 has been demonstrated to be the most expressed HDACs in glioblastoma. Our aim was to test whether Tub A could reverse the malignant phenotype of U87MG cells via the inhibition of HDAC6. Materials and Methods: U87MG cells were treated with cyclopamine (Cyp), TMZ, and Tub A. Two double treatments were performed as well (Cyp + Tub A and TMZ + Tub A). Colony formation, wound healing, Caspase‑Glo 3/7, quantitative reverse transcription–polymerase chain reaction, luciferase assay, and Western blot assays were conducted to determine clonogenic and migration capacity, apoptosis, activation of the Sonic Hedgehog pathway, acetylation of α‑tubulin and epithelial‑to‑mesenchymal transition, and autophagic flux of U87MG glioblastoma cells, respectively. Results: Tub A treatment caused a reversal of the U87MG malignant phenotype by reducing its clonogenic and migratory cellular potential, and inducing apoptosis. Sonic Hedgehog pathway inhibition, together with reversal of epithelial‑to‑mesenchymal transition and reduced autophagic flux, was also induced by the effect of Tub A. Conclusions: HDAC6 might be a good target for glioblastoma treatment

Panobinostat potentiates temozolomide effects and reverses epithelial-mesenchymal transition in glioblastoma cells

Glioblastoma is the most common form of glioma, as well as the most aggressive. Patients suffering from this disease have a very poor prognosis. Surgery, radiotherapy, and temozolomide are the only approved treatments nowadays. Panobinostat is a pan-inhibitor of histone deacetylases (HDACs) that has been shown to break some pathways which play an important role in cancer development. A global intention of using panobinostat as a therapeutic agent against glioblastoma is beginning to be a reality. We have treated the LN405 glioblastoma cell line with temozolomide, panobinostat, and combined treatment, in order to test apoptosis, colony formation, and a possible molecular reversion of the mesenchymal phenotype of the cells to an epithelial one. Our results show that panobinostat decreased N-cadherin levels in the LN405 glioblastoma cell line while it increased the expression of E-cadherin, which might be associated with a mesenchymal–epithelial transition in glioblastoma cells. Colony formation was reduced, and apoptosis was increased with treatments. Our research highlights the importance of panobinostat as a potential adjuvant therapy to be used with temozolomide to treat glioblastoma and the advantages of the combined treatment versus temozolomide alone, which is currently the first-line treatment used to treat this tumo

Tubastatin A, an inhibitor of HDAC6, enhances temozolomide‐induced apoptosis and reverses the malignant phenotype of glioblastoma cells

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 α-tubulin, 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 α-tubulin 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 temozolomide-induced apoptosis. Finally, HDAC6 inhibition decreased the expression of mesenchymal markers, contributing to reverse epithelial-mesenchymal transition in glioblastoma cells

Panobinostat and its combination with 3-deazaneplanocin-A induce apoptosis and inhibit In vitro tumorigenesis and metastasis in GOS-3 glioblastoma cell lines

Aim: Glioblastoma is the most malignant primary brain tumor. The treatment consists of surgery, with or without radiotherapy, and temozolomide, with a life expectancy of 12–15 months after diagnosis. Glioblastoma is resistant to conventional antitumor therapies. In this work, we present a preliminary in vitro study of two epigenetic drugs against GOS-3 glioblastoma cells. Methods: We used (1) panobinostat, a histone deacetylase inhibitor, and (2) 3-deazaneplanocin-A (DZ-Nep), an inhibitor of enhancer of zeste homolog 2 (EZH2) (enzyme of the polycomb repressor complex 2, polycomb group of proteins that trimethylate lysine 27 of histone 3-H3K27 me3-), as treatments that might modulate the PI3K pathway, affected in GOS-3 cells due to PTEN haploinsufficiency. The glioblastoma cell line GOS-3 was exposed to DZ-Nep and panobinostat treatments, separately and in combination, over a period of 2 days, after which cell migration, clonogenicity, and molecular expression characterization assays were performed. Results: Panobinostat alone or the combination of panobinostat plus DZ-Nep inhibited clonogenicity, metastasis, angiogenesis, epithelial–mesenchymal transition, and entry in the S phase of the cell cycle and induced apoptosis in GOS-3 glioblastoma cells. On the contrary, DZ-Nep inhibited cell migration (single treatment) and O(6)-methylguanine-DNA methyltransferase expression (DZ-Nep or double treatment). Conclusion: Panobinostat alone or the combination of panobinostat and DZ-Nep induce apoptosis and inhibit in vitro tumorigenesis and metastasis in GOS-3 glioblastoma cell lines