panobinostat and Thyroid-Carcinoma--Anaplastic

Anaplastic thyroid carcinoma (ATC) has poor prognosis, high mortality rate and lack of effective therapy. A synergic combination of PD-L1 antibody together with cell death promoting substances like deacetylase inhibitors (DACi) and multi-kinase inhibitors (MKI) could sensitize ATC cells and promote decay by autophagic cell death. The PD-L1-inhibitor atezolizumab synergized with panobinostat (DACi) and sorafenib (MKI) leading to significant reduction of the viability, measured by real time luminescence, of three different patient-derived primary ATC cells, of C643 cells and follicular epithelial thyroid cells too.

Topics: Aged; Aged, 80 and over; Antineoplastic Agents; Autophagy; Cell Death; Cell Line, Tumor; Humans; Male; Panobinostat; Sorafenib; Spheroids, Cellular; Thyroid Carcinoma, Anaplastic; Thyroid Neoplasms

Anaplastic thyroid cancers (ATCs) represent only 1%-2% of all thyroid tumors, but they account for up to 50% of the mortality. Treatment of differentiated thyroid carcinomas is well standardized and the use of radioiodine represents an essential step; in contrast, there is no standardized therapeutic approach for anaplastic tumors and their prognosis is poor. The resistance of ATC to radioiodine treatment is principally due to the absence of expression of the sodium iodide symporter (NIS), mainly due to epigenetic silencing. The acetylation status of histones is involved in the epigenetic control of gene expression and is usually disrupted in advanced thyroid cancer. Histone deacetylase inhibitors have been demonstrated as potent anticancer drugs with several different effects on cell viability and differentiation.. Stabilized ATC cell lines (BHT-101 and CAL-62) and primary cultures from patients who underwent thyroidectomy for ATC were treated with the histone deacetylase inhibitor LBH589. After treatment, we evaluated the expression and function of NIS. Gene expression was evaluated by real-time polymerase chain reaction (RT-PCR), NIS promoter activity was determined with a luciferase reporter assay, and protein expression was assessed through immunofluorescence. We tested the protein function by (125)I uptake and efflux experiments; finally the cytotoxic effect of (131)I was determined with a clonogenic assay.. Our results demonstrate that treatment with LBH589 leads to NIS RNA expression as shown by RT-PCR and luciferase assay, and to protein expression as determined by immunofluorescence in vitro and by immunohistochemistry in xenograft tumors. Moreover, (125)I uptake and efflux experiments show the correct protein function and iodine retention, which translate into cytotoxicity effects, as demonstrated by a clonogenic assay with (131)I.. This study supplies a new potential strategy for the treatment of ATC by modifying gene expression with the aim of inducing responsiveness towards radioiodine therapy.

Topics: Aged; Aged, 80 and over; Animals; Cell Line, Tumor; Female; Heterografts; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Iodine Radioisotopes; Male; Mice; Middle Aged; Neoplasm Transplantation; Panobinostat; Symporters; Thyroid Carcinoma, Anaplastic; Thyroid Neoplasms

Anaplastic thyroid carcinoma (ATC) has a rapidly fatal clinical course, being resistant to multimodal treatments. Microtubules, α/β tubulin heterodimers, are crucial in cell signaling, division and mitosis and are among the most successful targets for anticancer therapy. Panobinostat (LBH589) is a potent deacetylase inhibitor acting both on histones and nonhistonic proteins, including α-tubulin. In vitro LBH589, evaluated in three ATC cell lines (BHT-101, CAL-62 and 8305C), resulted in impairment of cell viability, inhibition of colony formation, cell cycle arrest and apoptosis induction. Mechanistically, we showed that LBH589 not only affected the expression of p21 and cyclin D1, but markedly determined microtubule stabilization as evidenced by tubulin acetylation and increased tubulin polymerization. In a SCID xenograft model implanted with CAL-62 cells, the cytotoxic properties of LBH589 were confirmed. The drug at the dose of 20 mg/kg significantly impaired tumor growth (final tumor volume 2.5-fold smaller than in untreated animals); at this dose, no relevant side effects were observed. In tumors of treated animals, a significant reduction of Ki67, which was negatively correlated with tubulin acetylation, was observed. Moreover, acetyl-tubulin levels negatively correlated with tumor volume at sacrifice, reinforcing the opinion that tubulin acetylation has a role in the inhibition of tumor growth. In conclusion, LBH589, acting on both histones and nonhistonic proteins in anaplastic thyroid cancer, appears to be a promising therapeutic agent for the treatment of this kind of cancer which is known not to respond to conventional therapy.

Topics: Acetylation; Animals; Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Line, Tumor; Female; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Histones; Humans; Hydroxamic Acids; Indoles; Mice; Mice, Nude; Panobinostat; Thyroid Carcinoma, Anaplastic; Thyroid Neoplasms; Tubulin; Tumor Burden; Xenograft Model Antitumor Assays

Anaplastic thyroid cancer cells are characterized by a mesenchymal phenotype, as revealed by spindle-shaped cells and absent or reduced levels of E-cadherin. Epigenetic silencing is considered one of the leading mechanisms of E-cadherin impairment, which causes the acquisition of the invasive and metastatic phenotype of anaplastic thyroid cancer.. In this study we investigated the effects of histone deacetylase inhibition on E-cadherin expression, cell motility, and invasion in anaplastic thyroid cancer cell cultures.. Three stabilized cell lines and primary cultures of anaplastic thyroid cancer were treated with various histone deacetylase inhibitors. After treatment, we evaluated histone acetylation by Western blotting and E-cadherin expression by RT-real time PCR. The proper localization of E-cadherin/β-catenin complex was assessed by immunofluorescence and Western blot. Transcription activity of β-catenin was measured by luciferase reporter gene and cyclin D1 expression. The effect on cell motility and invasion was studied both in vitro using scratch-wound and transwell invasion assays and in anaplastic thyroid carcinomas tumor xenografts in mice in vivo.. Histone deacetylase inhibition induced the E-cadherin expression and the proper membrane localization of the E-cadherin/β-catenin complex, leading to reduced cancer cell migration and invasion.. We here demonstrate an additional molecular mechanism for the anticancer effect of histone deacetylase inhibition. The antiinvasive effect in addition to the cytotoxic activity of histone deacetylase inhibitors opens up therapeutic perspectives for the anaplastic thyroid tumor that does not respond to conventional therapy.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Benzamides; beta Catenin; Cadherins; Cell Movement; Down-Regulation; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Mice; Mice, SCID; Neoplasm Invasiveness; Panobinostat; Protein Transport; Pyridines; Thyroid Carcinoma, Anaplastic; Thyroid Neoplasms; Tumor Cells, Cultured; Xenograft Model Antitumor Assays