HDAC-Linked "Proliferative" miRNA Expression Pattern in Pancreatic Neuroendocrine Tumors

Epigenetic factors are essentially involved in carcinogenesis, tumor promotion, and chemoresistance. Two epigenetic key players are miRNAs and histone deacetylases (HDACs). As previously shown by own theoretical databank analysis, the crosstalk between miRNAs and HDACs is relevant in different human chronic diseases and cancerogenic pathways. We aimed to investigate a potential connection between the expression of a well-defined subset of "proliferation-associated" miRNAs and the expression of HDACs as well as clinical parameters in pancreatic neuroendocrine tumors (pNETs).

MATERIALS AND METHODS

Expression levels of miRNA132-3p, miRNA145-5p, miRNA183-5p, miRNA34a-5p, and miRNA449a in 57 pNETs resected between 1997 and 2015 were measured and linked to the immunohistochemical expression pattern of members of the four HDAC classes on human tissue microarrays. All pNET cases were clinically and pathologically characterized according to published guidelines. Correlation analysis revealed a significant association between expression of specific miRNAs and two members of the HDAC family (HDAC3 and HDAC4). Additionally, a linkage between miRNA expression and clinico-pathological parameters like grading, TNM-staging, and hormone activity was found. Moreover, overall and disease-free survival is statistically correlated with the expression of the investigated miRNAs. Overall, we demonstrated that specific miRNAs could be linked to HDAC expression in pNETs. Especially miRNA449a (associated with HDAC3/4) seems to play an important role in pNET proliferation and could be a potential prognostic factor for poor survival. These first data could help, to improve our knowledge of the complex interactions of the epigenetic drivers in pNETs for further therapeutic approaches.

Panobinostat mediated cell death: a novel therapeutic approach for osteosarcoma

Osteosarcoma is an aggressive cancer with a poor long term prognosis. Neo-adjuvant poly-chemotherapy followed by surgical resection remains the standard treatment, which is restricted by multi-drug resistance. If first-line therapy fails, disease control and patient survival rate drop dramatically. We aimed to identify alternative apoptotic mechanisms induced by the histone deacetylase inhibitor panobinostat in osteosarcoma cells. Saos-2, MG63 and U2-OS osteosarcoma cell lines, the immortalized human osteoblast line hFOB and the mouse embryo osteoblasts (MC3T3-E1) were treated with panobinostat. Real time viability and FACS confirmed the cytotoxicity of panobinostat. Cell stress/death related factors were analysed by RT-qPCR and western blot. Cell morphology was assessed by electron microscopy. 10 nM panobinostat caused cell viability arrest and death in all osteosarcoma and osteoblast cells. P21 up-regulation was observed in osteosarcoma cells, while over-expression of p73 was restricted to Saos-2 (TP53^-/-). Survivin and Bcl-2 were suppressed by panobinostat. Endoplasmic reticulum (ER) stress markers BiP, CHOP, ATF4 and ATF6 were induced in osteosarcoma cells. The un-spliced Xbp was no further detectable after treatment. Autophagy players Beclin1, Map1LC3B and UVRAG transcripts over-expressed after 6 hours. Protein levels of Beclin1, Map1LC3B and p62 were up-regulated at 72 hours. DRAM1 was stable. Electron micrographs revealed the fragmentation and the disappearance of the ER and the statistically significant increase of autophagosome vesiculation after treatment. Panobinostat showed a synergistic suppression of survival and promotion of cell death in osteosarcoma cells. Panobinostat offers new perspectives for the treatment of osteosarcoma and other malignant bone tumours.

Selumetinib Activity in Thyroid Cancer Cells: Modulation of Sodium Iodide Symporter and Associated miRNAs

BACKGROUND

The MEK (mitogen-activated protein kinase)⁻inhibitor selumetinib led to increased radioiodine uptake and retention in a subgroup of patients suffering from radioiodine refractory differentiated thyroid cancer (RR-DTC). We aimed to analyse the effect of selumetinib on the expression of sodium iodide symporter (NIS; SLC5A5) and associated miRNAs in thyroid cancer cells.

METHODS

Cytotoxicity was assessed by viability assay in TPC1, BCPAP, C643 and 8505C thyroid cancer cell lines. NIS, hsa-let-7f-5p, hsa-miR-146b-5p, and hsa-miR-146b-3p expression was determined by quantitative RT-PCR. NIS protein was detected by Western blot. Radioiodine uptake was performed with a Gamma counter.

RESULTS

Selumetinib caused a significant reduction of cell viability in all thyroid cancer cell lines. NIS transcript was restored by selumetinib in all cell lines. Its protein level was found up-regulated in TPC1 and BCPAP cells and down-regulated in C643 and 8505C cells after treatment with selumetinib. Treatment with selumetinib caused a down-regulation of hsa-let-7f-5p, hsa-miR-146b-5p and hsa-miR-146b-3p in TPC1 and BCPAP cells. In 8505C cells, a stable or down-regulated hsa-miR-146b-5p was detected after 1h and 48h of treatment. C643 cells showed stable or up-regulated hsa-let-7f-5p, hsa-miR-146b-5p and hsa-miR-146b-3p. Selumetinib treatment caused an increase of radioiodine uptake, which was significant in TPC1 cells.

CONCLUSIONS

The study shows for the first time that selumetinib restores NIS by the inhibition of its related targeting miRNAs. Further studies are needed to clarify the exact mechanism activated by hsa-miR-146b-5p, hsa-miR-146b-3p and hsa-let7f-5p to stabilise NIS. Restoration of NIS could represent a milestone for the treatment of advanced RR-DTC.

Individualised Multimodal Treatment Strategies for Anaplastic and Poorly Differentiated Thyroid Cancer

The prognosis of anaplastic (ATC) and poorly differentiated thyroid cancer (PDTC) is poor, due to their radioiodine refractoriness (RAI-R), high metastatic potential and current lack of effective treatment strategies. We aimed to examine the efficacy of the tyrosine kinase inhibitors (TKIs) sorafenib and selumetinib and the histone deacetylase inhibitor (HDACI) panobinostat in patient-derived tumor tissue (PDTT) of ATCs/PDTCs, the expression of sodium iodide symporter (NIS) and radioiodine up-take (RAI-U). High Mobility Group AT-Hook 2 (HMGA2) and associated miRNAs expression was correlated with the clinical course of the patients. Inhibitory effects of panobinostat, sorafenib and selumetinib were measured by real time cell analyser xCELLigence in five PDTTs and human foreskin fibroblasts (HF) used as control. Expression of NIS, HMGA2 and associated miRNAs hsa-let-7f-5p, hsa-let-7b-5p, hsa-miR-146b-5p and hsa-miR-146b-3p was performed by RT-qPCR and Western blot. RAI-U was performed by Gamma Counter with I-131. Panobinostat showed the strongest cytotoxic effect (10 nM) in all PDTTs and HF and caused a significant over-expression of NIS transcript. TKIs were able to up-regulate NIS transcript in patient 5 and in HF. RAI-U was up-regulated after 24 h of treatment with TKIs and panobinostat in all PDTT and HF, except in patient 5. Selumetinib caused a significant suppression of HMGA2 in PDTT 1, 2, 4, 5 and HF; whereas sorafenib caused no change of HMGA2 expression. Panobinostat suppressed significantly HMGA2 in PDTT 2, 4 and HF. The expression of miRNAs hsa-let-7f-5p, has-let-7b-5p hsa-miR-146b-5p and hsa-miR-146b-3p was modulated heterogeneously. NIS protein level was over-expressed in three PDTTs (patients 1, 3 and 4) after 24 h of treatment with selumetinib, sorafenib and in particular with panobinostat. HF showed a stable NIS protein level after treatment. Panobinostat showed the strongest cytotoxicity in all treated PDTTs at the lowest dosage in comparison with TKI. All three compounds were able to modulate differently NIS, HMGA2 and related miRNAs. These factors represent valuable markers in PDTT for new treatment strategies for patients suffering from ATC/PDTC. Thus, the establishment of PDTT could be a useful tool to test the efficacy of compounds and to develop new and individualised multimodal treatment options for PDTCs and ATCs.

Epigenetic Modifications in Thyroid Cancer Cells Restore NIS and Radio-Iodine Uptake and Promote Cell Death

Epigenetic modifications have been identified as being responsible for the de-differentiation of thyroid tissue and its malignant transformation. Cell proliferation inhibitory effects of the pan-deacetylase inhibitors panobinostat, SAHA and Trichostatin A (TSA), the modulation of the sodium iodide symporter (NIS; SLC5A5), thyroid transcription factor 1 (TTF1), high mobility group A2 (HMGA2), and H19 and their putative targeting miRNAs have been evaluated in vitro. The cell viability was measured in five thyroid cancer cell lines (FTC133, TPC1, BCPAP, 8505C, C643) by real time cell analyzer xCELLigence. Expression of the above mentioned markers was performed by RT-qPCR and Western Blot. Radioiodine up-take was detected by Gamma Counter with I¹³¹. Cell viability decreased after treatment in all five cell lines. 10 nM panobinostat; 1 µM TSA or 10 µM SAHA caused a significant over-expression of NIS transcript in all five cell lines, whereas NIS protein was up-regulated in FTC133, BCPAP, and C643 cell lines only. Radioiodine up-take increased in FTC133 and C643 cells after 48 h of treatment with 10 nM panobinostat and 1 µM TSA. A significant down-regulation of the oncogene HMGA2 was detected in all five cell lines; except for TPC1 cells that were treated with 1 µM TSA. In accordance, hsa-let-7b-5p and hsa-let-7f-5p were stable or significantly over-expressed in all of the cell lines, except for TPC1 cells that were treated with 10 µM SAHA. TTF1 was significantly down-regulated in FTC133, BCPAP, and 8505C cells; whereas, TPC1 and C643 showed an up-regulated or stable expression. TTF1 was over-expressed in samples of human anaplastic thyroid cancer; whereas, it was down-regulated in follicular and undetectable in papillary thyroid cancer. H19 was over-expressed after 48 h treatment, except for BCPAP cells that were treated with panobinostat and SAHA. H19 was differently expressed in human anaplastic, follicular and papillary thyroid tumor samples. Deacetylase inhibitors reduced cell viability, restored NIS and H19, and suppressed the oncogenes HMGA2 and TTF1 in thyroid cancer cells.

Targeting autophagy in liver cancer

Autophagy is a catabolic cellular process conserved in animals. It is characterized by the main role of recycling all the non-functional products of the cells. Once, autophagy players detect non-functioning sub-cellular organelles and proteins, they start the so-called nucleation process. The organelles will be surrounded by a double membrane vesicle mainly constituted by endoplasmic reticulum (ER) membrane and autophagy proteins, e.g., MAP1LC3B, Beclin-1, VPS34, Unc-51 like autophagy activating kinase (ULK1) and ubiquitination-related proteins. Then the autophagic membrane will go through an elongation phase involving additional autophagy players. Once the autophagic vesicle is complete, the sub-cellular organelles will be isolated from the rest of the cytosol and driven to the final fusion with lysosomes. Here, the digestion process will end. Alteration and or impairment of autophagy have been shown to be correlated with development of diseases affecting the central nervous system, e.g., Alzheimer and other neurodegenerative diseases. Nonetheless, autophagy defect is responsible for tumorigenesis in blood and solid malignancies, in particular liver cancer. Malignancies of the liver are determined by several genetics and epigenetics mechanisms triggering the up-regulation of survival mechanisms and resistance to cell death. Furthermore, liver cancer could result from pathologic conditions like cirrhosis and fibrosis related to virus infection, aflatoxin, alcohol consumption and high fat diet together with insulin resistance. The role exerted by autophagy in the pathogenesis of the liver and tumor development has been evidenced in recent years. The alteration of autophagy assumes a fundamental role for liver tumorigenesis determining an accumulation of non-functional proteins and organelles that trigger oxidative stress leading to genotoxic stress and gene alterations. Furthermore, the absence of this degradation mechanism could prompt the cells to alter their metabolic status and turn into malignant cells. Interestingly, the heterozygous loss of function of Beclin-1 is able to trigger liver tumorigenesis or even the simple accumulation of proteins caused by the block of the final autolysosome fusion and degradation process is responsible for liver cancer development. This review highlights the importance of targeting the autophagy process in liver cancer in order to restore its function and to promote autophagy-mediated cell demise.

Chemoprevention with Enalapril and Aspirin in Men1(+/T) Knockout Mouse Model

Pancreatic neuroendocrine neoplasias (pNEN) are the most common cause of death in adult patients with multiple endocrine neoplasia type 1 (MEN1). So far, only few chemopreventive strategies (e.g., with somatostatin analogues) have been evaluated for MEN1 associated pNENs. In this experimental study on 75 Men1(+/T) knockout mice, the effect of aspirin (n = 25) and an inhibitor of angiotensin-I converting enzyme (enalapril, n = 25) compared to controls (n = 25) were evaluated as single chemopreventive strategies for pNENs after 6, 9, 12, 15, and 18 months. After each study period, mice were sacrificed and the resected pancreata were evaluated by histopathological analysis, immunostaining, and real-time PCR. PNEN size and number was measured. Aspirin and enalapril lead to a pNEN size reduction of 80% (167,518 vs. 838,876 µm2, p < 0.001) and 79% (174,758 vs. 838,876 µm2, p < 0.001) compared to controls. Furthermore, aspirin and enalapril treatment resulted in a significant reduction of the number of pNENs by 33%, (p = 0.04) and 41% (p = 0.002) respectively. The apoptosis marker caspase 3 revealed a higher positive expression in pNEN of treated Men1(+/T) mice. Immunostaining of VEGF in pNEN detected a downregulation of its expression in treated Men1(+/T) mice compared to the control group. REL A transcript was significantly downregulated in 18-months treated enalapril Men1(+/T) mice, but not in aspirin-treated Men1(+/T) mice. There was no significant difference in the Ki-67 index. Using a transgenic mouse model that imitates human MEN1, this study provides first evidence that aspirin and enalapril are effective chemopreventive agents that aid in the progression of pNENs.

Expression of hsa-let-7b-5p, hsa-let-7f-5p, and hsa-miR-222-3p and their putative targets HMGA2 and CDKN1B in typical and atypical carcinoid tumors of the lung

Typical and atypical carcinoid tumors belong to the neuroendocrine lung tumors. They have low recurrence and proliferation rate, lymph node, and distant metastases. Nevertheless, these tumors have shown a more aggressive behavior. In the last years, microRNAs were screened as new tumor markers for their potential diagnostic and therapeutic relevance. The expression of hsa-let-7b-5p, hsa-let-7f-5p, hsa-miR-222-3p, and their targets HMGA2 (high-mobility group A2) and CDKN1B (cyclin-dependent kynase inhibitor 1B, p27^kip1) was evaluated in this rare small group of patients. We analyzed the clinical data of all typical and atypical carcinoid tumors of patients who underwent surgical operation at Marburg University Hospital (n = 18) from 2000. Quantitative reverse transcription polymerase chain reaction was performed in formalin-fixed paraffin-embedded tumor tissue versus four tumor-free lung tissue samples. HMGA2 was stable or downregulated; only one patient showed a significant overexpression. CDKN1B showed a significant overexpression or a stable level; it was downregulated in two samples only. Hsa-miR-222-3p resulted almost stable or overexpressed except for two samples (significantly downregulated). Hsa-let-7f-5p was stable or overexpressed in the majority of analyzed samples, whereas hsa-let-7b-5p was significantly downregulated. HMGA2 and CDKN1B are differently expressed between atypical and typical carcinoid tumors, thus representing valid biomarkers for the classification of the two tumor groups. Hsa-let-7f-5p and HMGA2 are inversely correlated. Hsa-miR-222-3p does not correlate with its predicted target CDKN1B.

Comprehensive immunohistochemical analysis of histone deacetylases in pancreatic neuroendocrine tumors: HDAC5 as a predictor of poor clinical outcome

Epigenetic factors contribute to carcinogenesis, tumor promotion, and chemoresistance. Histone deacetylases (HDACs) are epigenetic regulators that primarily cause chromatin compaction, leading to inaccessibility of promoter regions and eventually gene silencing. Many cancer entities feature overexpression of HDACs. Currently, the role of HDACs in pancreatic neuroendocrine tumors (pNETs) is unclear. We analyzed the expression patterns of all HDAC classes (classes I, IIA, IIB, III, and IV) in 5 human tissue microarrays representing 57 pNETs resected between 1997 and 2013 and corresponding control tissue. All pNET cases were characterized clinically and pathologically according to recent staging guidelines. The investigated cases included 32 (56.1%) female and 25 (43.9%) male pNET patients (total n=57, 47.4% immunohistochemically endocrine positive). Immunohistochemical profiling revealed a significant up-regulation of all HDAC classes in pNET versus control, with different levels of intensity and extensity ranging from 1.5- to >7-fold up-regulation. In addition, expression of several HDACs (HDAC1, HDAC2, HDAC5, HDAC11, and Sirt1) was significantly increased in G3 tumors. Correlation analysis showed a significant association between the protein expression of HDAC classes I, III, and IV and rate of the pHH3/Ki-67-associated mitotic and proliferation index. Furthermore, especially HDAC5 proved as a negative predictor of disease-free and overall survival in pNET patients. Overall, we demonstrate that specific members of all 4 HDAC classes are heterogeneously expressed in pNET. Moreover, expression of HDACs was associated with tumor grading, proliferation markers, and patient survival, therefore representing interesting new targets in pNET treatment.

Fibromyalgia syndrome: metabolic and autophagic processes in intermittent cold stress mice

Fibromyalgia is characterized by widespread musculoskeletal pain, fatigue, and depression. The aim was to analyze potential mitochondrial dysfunction or autophagy in mice after exposure to intermittent cold stress (ICS). Muscle and liver specimens were obtained from 36 mice. Lactate dehydrogenase (LDH) activity was measured. Microtubule-associated protein light chain 3 (MAP1LC3B) and glycogen content were determined histologically; muscle ultrastructure by electron microscopy. Mitochondrial- and autophagy-related markers were analyzed by RT-qPCR and Western blotting. ATP level, cytotoxicity, and caspase 3 activity were measured in murine C2C12 myoblasts after ICS exposure. Coenzyme Q10B (COQ10B) transcript was up-regulated in limb muscle of ICS mice, whereas its protein content was stable. Cytochrome C oxidase 4 (COX4I1) and LDH activity increased in limb muscle of male ICS mice. Glycogen content was lower in muscle and liver tissue of male ICS mice. Electron micrographs of ICS mice specimens showed mitochondrial damage and autophagic vesicles. A significant up-regulation of autophagic transcripts of MAP1LC3B and BECLIN 1 (BECN1) was observed. Map1lc3b protein showed an aggregated distribution in ICS mice and SqSTM1/p62 (p62) protein level was stable. Furthermore, ATP level and caspase activity, detected as apoptotic marker, were significantly lowered after ICS exposure in differentiated C2C12 myoblasts. The present study shows that ICS mice are characterized by mitochondrial dysfunction, autophagic processes, and metabolic alterations. Further investigations could dissect autophagy process in the proposed model and link these mechanisms to potential therapeutic options for fibromyalgia.

MicroRNAs let7 expression in thyroid cancer: correlation with their deputed targets HMGA2 and SLC5A5

PURPOSE

Thyroid cancer (TC), the most common endocrine malignancy, increases its incidence worldwide. MicroRNAs have been shown to be abnormally expressed in tumors and could represent valid diagnostic markers for patients affected by TC. Our aim was to analyze the expression of tumorsuppressor hsa-let7b-5p and hsa-let7f-5p, together with their predicted targets SLC5A5 (NIS) and HMGA2, in papillary (PTC), follicular (FTC) and anaplastic (ATC).

METHODS

8 FTC, 14 PTC, 12 ATC and three normal thyroid tissue samples were analyzed for the expression of pre-let7b, hsa-let7b-5p and hsa-let7f-5p as SLC5A5 and HMGA2 by RT-qPCR. Data were analyzed by REST 2008.

RESULTS

FTC patients showed a significant down-regulation of hsa-let7b-5p and its precursor. hsa-let7f-5p was overexpressed, and SLC5A5 was strongly suppressed. HMGA2 was overexpressed, reflecting no correlation with its regulatory let7 miRNAs. PTC samples were characterized by up-regulation of hsa-let7b-5p, its precursor and hsa-let7f-5p. SLC5A5 was strongly suppressed in comparison with normal thyroid tissue. HMGA2 was overexpressed, as shown in FTC, also. ATC samples showed a similar miRNAs profile as PTC. In contrast with FTC and PTC, these patients showed a stable or up-regulated SLC5A5 and HMGA2.

CONCLUSIONS

Expression of HMGA2 is not correlated with the regulatory let7 miRNAs. Interestingly, SLC5A5 was down-regulated in FTC and PTC. Its expression could be modulated by hsa-let-7f-5p. ATC showed a loss of SLC5A5/hsa-let7f-5p correlation. SLC5A5, in ATC, needs further investigation to clarify the genetic/epigenetic mechanism altering its expression.

Autophagy-related cell death by pan-histone deacetylase inhibition in liver cancer

Autophagy is a homeostatic, catabolic degradation process and cell fate essential regulatory mechanism. Protracted autophagy triggers cell death; its aberrant function is responsible for several malignancies. Panobinostat, a potent pan-deacetylase inhibitor, causes endoplasmic reticulum stress-induced cell death. The aim of this study was to investigate the role of autophagy in deacetylase inhibitor-triggered liver cancer cell death.HepG2 (p53wt) and Hep3B (p53 null) liver cancer cell lines were exposed to panobinostat. RT-qPCR and western blot confirmed autophagic factor modulation. Immuno-fluorescence, -precipitation and -histochemistry as well as transmission electron microscopy verified autophagosome formation. The cytotoxicity of panobinostat and autophagy modulators was detected using a real time cell viability assay.Panobinostat induced autophagy-related factor expression and aggregation. Map1LC3B and Beclin1 were significantly over-expressed in HepG2 xenografts in nude mice treated with panobinostat for 4 weeks. Subcellular distribution of Beclin1 increased with the appearance of autophagosomes-like aggregates. Cytosolic loss of p53, in HepG2, and p73, in Hep3B cells, and a corresponding gain of their nuclear level, together with modulation of DRAM1, were observed. Autophagosome aggregation was visible after 6 h of treatment. Treatment of cells stably expressing GFP-RFPtag Map1LC3B resulted in aggregation and a fluorescence switch, thus confirming autophagosome formation and maturation. Tamoxifen, an inducer of autophagy, caused only a block in cell proliferation; but in combination with panobinostat it resulted in cell death.Autophagy triggers cell demise in liver cancer. Its modulation by the combination of tamoxifen and panobinostat could be a new option for palliative treatment of hepatocellular carcinoma.

Exogenous hepatitis B virus envelope proteins induce endoplasmic reticulum stress: involvement of cannabinoid axis in liver cancer cells

HBV represents the most common chronic viral infection and major cause of hepatocellular carcinoma (HCC), although its exact role in liver tumorigenesis is unclear. Massive storage of the small (SHBs), middle (MHBs) and large surface (LHBs) HBV envelope proteins leads to cell stress and sustained inflammatory responses. Cannabinoid (CB) system is involved in the pathogenesis of liver diseases, stimulating acute and chronic inflammation, liver damage and fibrogenesis; it triggers endoplasmic reticulum (ER) stress response. The aim of our work was to investigate the activation of ER stress pathway after ectopic HBV envelope proteins expression, in liver cancer cells, and the role exerted by CB receptors. PCR, immunofluorescence and western blotting showed that exogenous LHBs and MHBs induce a clear ER stress response in Huh-7 cells expressing CB1 receptor. Up-regulation of the chaperone BiP/GRP78 (Binding Immunoglobulin Protein/Glucose-Regulated Protein 78) and of the transcription factor CHOP/GADD153 (C/EBP Homologous Protein/Growth Arrest and DNA Damage inducible gene 153), phosphorylation of PERK (PKR-like ER Kinase) and eIF2α (Eukaryotic Initiation Factor 2α) and splicing of XBP1 (X-box binding protein 1) was observed. CB1-/- HepG2 cells did not show any ER stress activation. Inhibition of CB1 receptor counteracted BiP expression in transfected Huh-7 and in HBV+ PLC/PRF/5 cells; whereas no effect was observed in HBV- HLF cells. These results suggest that HBV envelope proteins are able to induce the ER stress pathway. CB1 expression is directly correlated with ER stress function. Further investigations are needed to clarify the involvement of cannabinoid in HCC progression after HBV infection.

The BMI1 inhibitor PTC-209 is a potential compound to halt cellular growth in biliary tract cancer cells

BMI1 is a core component of the polycomb repressive complex 1 (PRC1) and is up-regulated in biliary tract cancer (BTC), contributing to aggressive clinical features. In this study we investigated the cytotoxic effects of PTC-209, a recently developed inhibitor of BMI1, in BTC cells. PTC-209 reduced overall viability in BTC cell lines in a dose-dependent fashion (0.04 - 20 µM). Treatment with PTC-209 led to slightly enhanced caspase activity and stop of cell proliferation. Cell cycle analysis revealed that PTC-209 caused cell cycle arrest at the G1/S checkpoint. A comprehensive investigation of expression changes of cell cycle-related genes showed that PTC-209 caused significant down-regulation of cell cycle-promoting genes as well as of genes that contribute to DNA synthesis initiation and DNA repair, respectively. This was accompanied by significantly elevated mRNA levels of cell cycle inhibitors. In addition, PTC-209 reduced sphere formation and, in a cell line-dependent manner, aldehyde dehydrogease-1 positive cells. We conclude that PTC-209 might be a promising drug for future in vitro and in vivo studies in BTC.

Additive antitumour response to the rabbit VX2 hepatoma by combined radio frequency ablation and toll like receptor 9 stimulation

INTRODUCTION

Radiofrequency ablation (RFA), a palliative therapeutic option for solid hepatic tumours, stimulates localised and systemic antitumour cytotoxic T cells. We studied how far addition of CpG B oligonucleotides, toll like receptor (TLR) 9 agonists, would increase the antitumoural T cell response of RFA in the highly aggressive VX2 hepatoma.

METHODS

Rabbits were randomised to receive RFA, CpG B, their combination or no therapy. The antitumour efficacy of RFA alone or in combination with CpG B was further tested by rechallenging a separate group with intravenously injected VX2 tumour cells after 120 days. Animals were assessed for survival, tumour size and spread, and tumour and immune related histological markers after 120 days. Peripheral blood mononuclear cells were tested for tumour-specific T cell activation and cytotoxicity. Immune modulatory cytokines tumour necrosis factor α, interleukin (IL)-2/IL-8/IL-10/IL-12 and interferon γ, and vascular endothelial growth factor were measured in serum.

RESULTS

Mean survival of untreated animals was 36 days, as compared with 97, 78 and 114 days for RFA, CpG and combination therapy, respectively. Compared with untreated controls, antitumour T cell stimulation/cytotoxicity increased 26/16-fold, 32/17-fold and 50/38-fold 2 weeks after RFA, CpG and combination treatments, respectively. The combination inhibited tumour spread to lungs and peritoneum significantly and prohibited new tumour growth in animals receiving a secondary systemic tumour cell injection. RFA alone induced a Th1 cytokine pattern, while IL-8 and IL-10 were only upregulated in CpG treated animals and controls.

CONCLUSIONS

The combination of TLR9 stimulation with RFA resulted in a potentiated antitumour T cell response and cytotoxicity in the VX2 tumour model. Only this combination prevented subsequent tumour spread and resulted in a significantly improved survival, justifying the need for further exploration of the combination of ablative therapies and TLR9 agonists in liver cancer.

Morphological Alterations in Gastrocnemius and Soleus Muscles in Male and Female Mice in a Fibromyalgia Model

BACKGROUND

Fibromyalgia (FM) is a chronic musculoskeletal pain disorder, characterized by chronic widespread pain and bodily tenderness and is often accompanied by affective disturbances, however often with unknown etiology. According to recent reports, physical and psychological stress trigger FM. To develop new treatments for FM, experimental animal models for FM are needed to be development and characterized. Using a mouse model for FM including intermittent cold stress (ICS), we hypothesized that ICS leads to morphological alterations in skeletal muscles in mice.

METHODS

Male and female ICS mice were kept under alternating temperature (4 °C/room temperature [22 °C]); mice constantly kept at room temperature served as control. After scarification, gastrocnemius and soleus muscles were removed and snap-frozen in liquid nitrogen-cooled isopentane or fixed for electron microscopy.

RESULTS

In gastrocnemius/soleus muscles of male ICS mice, we found a 21.6% and 33.2% decrease of fiber cross sectional area (FCSA), which in soleus muscle concerns the loss of type IIa and IIx FCSA. This phenomenon was not seen in muscles of female ICS mice. However, this loss in male ICS mice was associated with an increase in gastrocnemius of the density of MIF+ (8.6%)-, MuRF+ (14.7%)-, Fbxo32+ (17.8%)-cells, a 12.1% loss of capillary contacts/muscle fiber as well as a 30.7% increase of damaged mitochondria in comparison with male control mice. Moreover, significant positive correlations exist among densities (n/mm(2)) of MIF+, MuRF+, Fbxo32+-cells in gastrocnemius/ soleus muscles of male ICS mice; these cell densities inversely correlate with FCSA especially in gastrocnemius muscle of male ICS mice.

CONCLUSION

The ICS-induced decrease of FCSA mainly concerns gastrocnemius muscle of male mice due to an increase of inflammatory and atrogenic cells. In soleus muscle of male ICS and soleus/gastrocnemius muscles of female ICS mice morphological alterations seem to occur not at all or delayed. The sex-specificity of findings, which is not easily reconciled with the epidemiology of FM (female predominance), implicate that gastrocnemius muscle of male ICS mice should preferentially be used for future investigations with FM. Moreover, we suggest to investigate morphological and/or molecular alterations at different time-points (up to two weeks) after ICS.

Endoplasmic Reticulum Stress in Pancreatic Neuroendocrine Tumors is Linked to Clinicopathological Parameters and Possible Epigenetic Regulations

BACKGROUND

Endoplasmic reticulum (ER) stress is a highly-conserved cellular defense mechanism in response to perturbations of ER function. The role of ER stress in pancreatic neuroendocrine tumors (pNET) still remains unclear.

MATERIALS AND METHODS

We analyzed the protein expression pattern of the four key players of ER stress, (chaperone binding imunoglobluin protein (BiP), C/EBP homologous protein (CHOP), activating transcription factor 4 (ATF4) and caspase 4) as well as histone deacetylases (HDACs) by a tissue microarray (TMA) of 49 human pNET resected between 1997 and 2013 following, extensive clinicopathological characterization.

RESULTS

Immunohistochemical profiling revealed a significant up-regulation of BiP, ATF4, CHOP and caspase 4 in pNET cases compared to normal controls. Correlated to clinicopathological parameters especially BiP expression could be linked to higher grading and proliferation as well as to lower survival probability. Finally, expression of ER stress markers correlated with HDAC expression in situ and pharmalogical inhibition by panobinostat significantly reduced cell viability in vitro.

CONCLUSION

Up-regulation of ER stress in pNET indicates the presence and engagement of ER stress signaling in this tumor entity demonstrating another possible anticancer therapy option in pNET.

Gallotannin is a DNA damaging compound that induces senescence independently of p53 and p21 in human colon cancer cells

The plant secondary metabolite gallotannin (GT) is the simplest hydrolyzable tannin shown to have anti-carcinogenic properties in several cell lines and to inhibit tumor development in different animal models. Here, we determined if GT induces senescence and DNA damage and investigated the involvement of p53 and p21 in this response. Using HCT116 human colon cancer cells wildtype for p53(+/+) /p21(+/+) and null for p53(+/+) /p21(-/-) or p53(-/-) /p21(+/+) , we found that GT induces senescence independently of p21 and p53. GT was found to increase the production of reactive oxygen species (ROS) by altering the redox balance in the cell, mainly by reducing the levels of glutathione and superoxide dismutase (SOD). Using the key antioxidants N-acetyl cysteine, dithiothreitol, SOD, and catalase, we showed that ROS were partially involved in the senescence response. Furthermore, GT-induced cell cycle arrest in S-phase in all HCT116 cell lines. At later time points, we noticed that p53 and p21 null cells escaped complete arrest and re-entered cell cycle provoking higher rates of multinucleation. The senescence induction by GT was irreversible and was accompanied by significant DNA damage as evidenced by p-H2AX staining. Our findings indicate that GT is an interesting anti colon cancer agent which warrants further study.

The pan-deacetylase inhibitor panobinostat affects angiogenesis in hepatocellular carcinoma models via modulation of CTGF expression

Post-translational modifications of chromatin components are significantly involved in the regulation of tumor suppressor gene and oncogene expression. Connective tissue growth factor (CTGF) is an epigenetically regulated growth factor with functions in angiogenesis and cell-matrix interactions and plays a pivotal role in hepatocellular carcinoma (HCC). The pharmacologic inhibition of histone and protein deacetylases represents a new approach to interfere with pathways of apoptosis and angiogenesis. We investigated the effect of the pan-deacetylase inhibitor panobinostat (LBH589) on human HCC cell lines HepG2 (p53wt) and Hep3B (p53null) and in a subcutaneous xenograft model and explored the influence on angiogenesis. Specimens were characterized by quantitative real-time PCR. Protein was separated for western blotting against CTGF, VEGF, VEGF receptor-1 (VEGFR-1/FLT-1), VEGF receptor-2 (VEGFR-2/KDR), MAPK and phospho-MAPK. In vivo, HepG2 cells were xenografted to NMRI mice and treated with daily i.p. injections of 10 mg/kg panobinostat. After 1, 7 and 28 days, real-time PCR was performed. Immunohistochemistry and western blotting were examined after 28 days. An increased significant expression of CTGF was only seen after 24 h treatment with 0.1 µM panobinostat in HepG2 cells and Hep3B cells, whereas after 72 h treatment CTGF expression clearly decreased. In the xenografts, treatment with panobinostat showed a minimal CTGF expression after 1 day and 4 weeks, respectively. In vitro as well as in vivo, VEGF was not affected by panobinostat treatment at any time. In conclusion, panobinostat influences extracellular signaling cascades via CTGF-dependent pathways.

3-Deazaneplanocin A May Directly Target Putative Cancer Stem Cells in Biliary Tract Cancer

BACKGROUND/AIM

Polycomb repressive complex 2 (PRC2), an epigenetic master regulator, contributes to progression and development of biliary tract cancer (BTC). The present study investigated the effects of the PRC2 inhibitor 3-deazaneplanocin A (DZNep) on BTC cell lines.

MATERIALS AND METHODS

In vitro effects of DZNep treatment were analyzed for cell viability, gene expression and functional characteristics of cancer stem cell (CSC).

RESULTS

DZNep treatment caused a cell line- and dose-dependent decrease in viability. In the EGI-1 cell line, a direct cytotoxic effect was accompanied by mRNA down-regulation of the PRC2 core components, cyclins as well as of CSC-related genes. Furthermore, DZNep affected putative CSCs by reduction of sphere formation and aldehyde dehydrogenase-1-positive cells. The stem cell characteristics of these subpopulations were verified by real-time polymerase chain reaction analysis.

CONCLUSION

Taken together, our results show that DZNep might be a promising pharmacological agent for future therapies regarding BTC.

The pan-deacetylase inhibitor panobinostat suppresses the expression of oncogenic miRNAs in hepatocellular carcinoma cell lines

Deacetylase inhibitors (DACi) are a new class of drugs with a broad spectrum of mechanisms that favor their application in cancer therapy. Currently, the exact mechanisms and cellular effects of DACi have not been fully elucidated. In addition to their effects on histone acetylation, DACi can interfere with gene expression via miRNA pathways. Treatment with panobinostat (LBH589), a novel potent DACi, led to the highly aberrant modulation of several miRNAs in hepatocellular carcinoma (HCC) cell lines as shown by miRNA array analysis. Among them, hsa-miR-19a, hsa-miR-19b1 and the corresponding precursors were down-regulated by panobinostat in TP53(-/-) Hep3B and TP53(+/+) HepG2 cell lines; hsa-miR30a-5p mature form only was suppressed in both HCC cell lines, as confirmed by further RT-qPCR analysis. In HCC cell lines, panobinostat caused the upregulation of the predicted miRNA targets APAF1 and Beclin1 protein levels. Transfection with oligonucleotides mimicking these miRNAs led to an increase in the viability rate of both cell lines as analyzed by impedance-based real-time cell analysis. In addition, transfecting miRNA mimicking oligonucleotides resulted in the decrease of APAF1, Beclin1 and PAK6 at the protein level, proving the regulating influence of the investigated miRNAs on gene final products. The overexpression of the above mentioned oncomiRs in Hep3B and HepG2 cell lines leads to cell proliferation and downregulation of cell death associated proteins. In our model, panobinostat exerts its anti-cancer effect by suppressing these miRNAs and restoring the expression of their corresponding tumor suppressor targets.

Ileal neuroendocrine tumors show elevated activation of mammalian target of rapamycin complex

BACKGROUND

Neuroendocrine tumors (NETs) of the ileum are sporadic tumors derived from submucosal gastrointestinal stem cells. They often show clinical symptoms only after hepatic metastasation when curative therapy is limited or impossible. In this study, we analyzed the expression of the candidate genes mammalian target of rapamycin (mTOR), alpha thalassemia/mental retardation syndrome X-linked (ATRX), and death domain-associated protein (DAXX) to investigate the specific oncogenetics and potential therapeutic options for ileal NETs.

METHODS

In a prospective database, all patients who underwent surgical removal of a NET of the ileum between 2001 and 2011 were specified. Expression analysis was performed for mTOR, ATRX, and DAXX by immunohistochemistry of paraffin-embedded tumor samples. To evaluate the results the immunoreactive score was applied. Normal tissue and tumor tissue were analyzed for the comparison of gene expression levels using quantitative-real-time polymerase chain reaction for ATRX and mTOR genes. Results were correlated under pathologic and clinical aspects.

RESULTS

A total of 69 patients were admitted to the study. Positive cytosolic expression of the potential oncogene mTOR was immunohistochemically detected in 76.2% of the human probes. A loss of nuclear ATRX expression was detected in 13.0% of the samples. A nonexpression of the DAXX-protein in cell nuclei was not found (0%). Gene transcript levels did not show a significant alteration in ileal NETs in comparison with normal tissue.

CONCLUSIONS

mTOR is overexpressed in ileal NETs. Additionally, the loss of ATRX expression was registered, thus underlying a tumorigenic role in a subgroup of these tumors. To enable potential therapeutic application of mTOR inhibitors, further trials with larger study groups are needed.

4,5-Diaryl imidazoles with hydroxamic acid appendages as anti-hepatoma agents

INTRODUCTION

Hepatocellular carcinoma (HCC) is the most abundant tumour of the liver with rising patient numbers in the Western world countries. Despite newly approved drugs like protein kinase inhibitors the survival rate is still poor.

METHODS

In order to identify potential new drugs for the treatment of HCC we investigated the real-time cell viability, apoptosis induction (sub-G1 cells), and HDAC (histone deacetylase) activity of two hepatocellular cancer cell lines HepG2 and Hep3B treated with new imidazole-tethered hydroxamates.

RESULTS

The tested cinnamyl hydroxamates exhibited significant antiproliferative and cytotoxic activity in HCC cells as apparent from high sub-G1 cell levels in flow cytometric cell cycle analyses. In Hep3B cells HDAC inhibition was observed comparable in magnitude to that induced by the clinically applied HDAC inhibitor SAHA (Zolinza, Vorinostat).

CONCLUSIONS

The new imidazolyl hydroxamic acids lend themselves as a possible alternative to SAHA in the therapy of HCC. Even more so since similar 4,5-diarylimidazoles lacking only the hydroxamate functionality were previously shown in animal studies to be well tolerated and orally applicable.