Modulation of Pancreatic Neuroendocrine Neoplastic Cell Fate by Autophagy-Mediated Death

INTRODUCTION

Autophagic cell death in cancer cells can be mediated by inhibition of deacetylases. Although extensive studies have focused on the autophagic process in cancer, little is known about the role of autophagy in degrading cytosolic and nuclear components of pancreatic neuroendocrine neoplastic (pNEN) cells leading to cell death, thus improving the therapy of patients affected by pNEN.

METHODS

2D and 3D human pNEN and pancreatic stellate cells were treated with panobinostat and bafilomycin. Autophagy markers were detected by RT-qPCR, immunofluorescence, and Western blot. Autophagosomes were detected by electron microscopy and their maturation by real-time fluorescence of LC3B stable transfected cells. ChIP was performed at the cAMP responsive element. Immunofluorescence was performed in murine pancreatic tissue.

RESULTS

We observed that pan-deacetylase inhibitor panobinostat treatment causes autophagic cell death in pNEN cells. We also found that although AMPK-α phosphorylation is counterbalanced by phosphorylated AKT, it is not capable to inhibiting autophagic cell death. However, the binding activity of the cAMP responsive element is prompted by panobinostat. Although autophagy inhibition prevented autophagosome synthesis, maturation, and cell death, panobinostat treatment induced the accumulation of mature autophagosomes in the cytosol and the nucleus, leading to disruption of the organelles, cellular digestion, and decay. Observation of autophagosome membrane proteins Beclin1 and LC3B aggregation in murine pancreatic islets indicates that autophagy restoration may also lead to autophagosome aggregation in murine insulinoma cells. A basal low expression of autophagy markers was detectable in patients affected by pNEN, and, interestingly, the expression of these markers was significantly lower in metastatic pNEN.

DISCUSSION/CONCLUSION

Our study highlights that the autophagy functional restoration and prolongation of this catabolic process, mediated by inhibition of deacetylase, is responsible for the reduction of pNEN cells. Prompting of autophagy cell death could be a promising strategy for the therapy of pNEN.

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.

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.

Contrast-enhanced ultrasound (CEUS) in hepatic lymphoma: retrospective evaluation in 38 cases

PURPOSE

Description of contrast-enhanced ultrasound (CEUS) patterns of hepatic lymphoma.

MATERIALS AND METHODS

Over a period of 6 years and 1 month from January 2006 to January 2012, n = 38 patients with histological or clinically apparent hepatic lymphoma were studied by means of CEUS prior to B-mode imaging.

RESULTS

Using B-mode imaging, lesions were hypoechoic in n = 37 (97.4 %) cases, while a focal lymphoma lesion was echo-rich in 1 case (2.6 %). For comparison, with CEUS, a hyperenhanced signal during the arterial phase was observed in n = 9 (23.7 %), an isoenhanced signal in n = 17 (44.7 %) and a hypoenhanced signal in n = 12 (31.6 %) cases. During the portal phase n = 2 (5.3 %) lesions were isoenhanced and n = 36 (94.7 %) were hypoenhanced followed by a hypoenhancement in n = 38 (100 %) cases in the late phase.

CONCLUSION

Lymphomas of the liver can cause different contrast accumulation in the arterial phase of CEUS. Furthermore, a clear differentiation from other malignant liver lesions such as metastases is crucial as different contrast accumulation in the arterial phase of CEUS is observed. In the late phase, hepatic lymphomas lead to a hypoenhancement in CEUS, also known as a "wash-out" phenomenon. In conclusion, CEUS is helpful to differentiate hepatic lesions by means of evaluating the malignancy or benignancy. In this regard, the application of CEUS can help to find the right diagnosis. A final discrimination between malignant liver lesions, such as liver lymphomas, metastasis or HCC, remains impossible.

Percutaneous ultrasound-guided radiofrequency ablation (RFA) using saline-perfused (wet) needle electrodes for the treatment of hepatocellular carcinoma--long term experience

PURPOSE

For many reasons, resection of hepatocellular cancer (HCC) is not feasible in most cases. Radiofrequency (RFA) ablation has proven to be an effective minimally invasive alternative. It has been shown in ex vivo and animal trials that needle applicators perfused with isotonic saline solution could be an effective approach to enlarging the coagulation zone. However, long term survival data for the treatment of HCC are not yet available.

MATERIALS AND METHODS

37 patients with a total of 64 histologically proven HCC with a maximum of 3 tumors of up to 6 cm and a contraindication to partial liver resection or orthotopic liver transplantation were treated with the Integra HiTT106 using wet monopolar single, wet bipolar double or wet triple needle electrodes. The mean HCC size was 37.7 mm (range 15 to 60 mm). Follow-up examinations were performed 2 days and 1, 3, 6, 9 months after RFA and every 6 months thereafter. The survival rate was calculated from the time of the first RFA session.

RESULTS

1, 2 and 5-year survival was 24/32 (75%), 14/31 (45%) and 3/21 (14%) overall; 18/19 (95%), 12/18 (67%) and 3/10 (30%) for HCC Child A; and 6/13 (46%), 2/13 (15%) and 0/11 (0%), for HCC Child B. Complete remission was achieved in 86.5 % of the patients (total: 32 out of 37, multi-needle 18 / 21, single needle 14 / 16). Distant recurrence occurred overall in 20 out of 37 patients (54%), including 9 of 21 treated with multiple needles (43% of patients) and 11 of the 16 patients treated with a single electrode (69%). The overall complication rate was 10.8%. Local recurrence was found for tumors measuring 3 cm-5 cm (n=28) in 7 out of 13 cases after single electrode RFA and in 1 out of 15 after multiple electrode treatment (significant, p=0.009). No significant difference between the single and multi-needle group was found for tumors >5 cm and <3 cm.

CONCLUSION

RFA using multiple wet electrodes shows promise as an effective method for treating inoperable HCC especially in cases with well-preserved liver function. Multiple electrodes seem to be superior to single electrodes with respect to the local recurrence rate for tumors between 3 and 5 cm.