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Aktuellste Publikationen

Exp Biol Med (Maywood). 2017 Jan 1:1535370217738730. doi: 10.1177/1535370217738730. [Epub ahead of print]

Microcirculatory disturbances and cellular changes during progression of hepatic steatosis to liver tumors.

Abstract

Non-alcoholic fatty liver disease is closely associated with metabolic syndrome and comprises a pathological spectrum of liver disease ranging from steatosis to steatohepatitis and can progress to fibrosis/cirrhosis and hepatocellular carcinoma. In 2013, a mouse model was described that mimics non-alcoholic fatty liver disease progression from steatohepatitis to tumors in a short time span and with high incidence. As microcirculatory disturbances play a crucial role in liver disease, the suitability of the steatosis-inflammation-tumor model for microcirculatory studies was assessed. Herein, we present a comprehensive view on morphological, microvascular, cellular, and functional aspects of non-alcoholic fatty liver disease progression in the steatosis-inflammation-tumor model using intravital microscopy, biochemical, and histological techniques. Mice develop steatohepatitis, mild fibrosis, and liver tumors at ages of 6, 12, and 20 weeks, respectively. Non-alcoholic fatty liver disease progression was accompanied by several general aspects of disease severity like increasing liver/body weight index, non-alcoholic fatty liver disease activity score, and hepatocellular apoptosis. Intravital microscopic analysis revealed significant changes in hepatic microcirculation with increasing structural alterations, elevated leukocyte adherence, and impaired nutritive perfusion. Non-alcoholic fatty liver disease was further characterized by a lower sinusoidal density with a striking rise at 20 weeks. The characteristic microcirculatory changes make the model a convenient tool for analysis of microcirculation during progression from steatosis to liver tumor. Impact statement Significant alterations of microcirculation contribute to progression of NAFLD, a chronic liver disease with increasing medical and socio-economic impact. Characterization of microcirculation in a NAFLD model reflecting all relevant stages of disease progression was still missing. Thus, we evaluated microcirculatory and cellular changes in a steatosis-inflammation-tumor model using in vivo microscopy. Analyses revealed increasing structural alterations, elevated leukocyte-endothelial interaction, and impaired nutritive perfusion. Thus, this model is suitable for further studies investigating therapeutic approaches targeting these progressive microcirculatory disturbances.

KEYWORDS:

Non-alcoholic fatty liver disease; hepatic microcirculation; hepatocellular carcinoma; intravital microscopy; steatohepatitis

Oncotarget. 2017 Jul 15;8(41):69756-69767. doi: 10.18632/oncotarget.19263. eCollection 2017 Sep 19.

Application of in vivo imaging techniques to monitor therapeutic efficiency of PLX4720 in an experimental model of microsatellite instable colorectal cancer.

Abstract

OBJECTIVES:

Patient-derived tumor cell lines are a powerful tool to analyze the sensitivity of individual tumors to specific therapies in mice. An essential prerequisite for such an approach are reliable quantitative techniques to monitor tumor progression in vivo.

METHODS:

We have employed HROC24 cells, grown heterotopically in NMRI Foxn1nu mice, as a model of microsatellite instable colorectal cancer to investigate the therapeutic efficiencies of 5'-fluorouracil (5'-FU) and the mutant BRAF inhibitor PLX4720, a vemurafenib analogue, by three independent methods: external measurement by caliper, magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-(18F)fluoro-D-glucose (18F-FDG).

RESULTS:

Repeated measure ANOVA by a general linear model revealed that time-dependent changes of anatomic tumor volumes measured by MRI differed significantly from those of anatomic volumes assessed by caliper and metabolic volumes determined by PET/CT. Over the investigation period of three weeks, neither 5'-FU, PLX4720 nor a combination of both drugs affected the tumor volumes. Also, there was no drug effect on the apparent diffusion constant (ADC) value as detected by MRI. Interestingly, however, PET/CT imaging showed that PLX4720-containing therapies transiently reduced the standardized uptake value (SUV), indicating a temporary response to treatment.

CONCLUSIONS:

5'-FU and PLX4720 were largely ineffective with respect to HROC24 tumor growth. Tumoral uptake of 18F-FDG, as expressed by the SUV, proved as a sensitive indicator of small therapeutic effects. Metabolic imaging by 18F-FDG PET/CT is a suitable approach to detect effects of tumor-directed therapies early and even in the absence of morphological changes.

KEYWORDS:

5’-fluorouracil; PLX4720; colorectal cancer; in vivo imaging; mouse model

J Cancer. 2017 Jul 1;8(10):1744-1749. doi: 10.7150/jca.17972. eCollection 2017.

Metformin Inhibits Gemcitabine Induced Apoptosis in Pancreatic Cancer Cell Lines.

Abstract

Many preclinical and clinical studies are currently evaluating metformin in combination with classical therapeutic agents as anti-cancer therapy. In this study we used three distinct pancreatic cancer cell lines and evaluated cell death by trypan blue assay and Western Blots using antibodies directed against cleaved caspase 3 and PARP. Surprisingly, we observed that 20mM metformin did not enhance, but rather inhibited gemcitabine induced cell death in murine 7265PDA, 6606PDA and 6606l cells. Microenvironmental aspects such as oxygen supply or the pH value did not influence the inhibition of cancer cell apoptosis by metformin. Glucose concentration in the medium, however, had a major effect on the impact of metformin. Medium with 0.5g/L glucose strongly increased metformin induced apoptosis and also prevented the inhibitory effect of metformin on gemcitabine induced cell apoptosis, when compared with medium containing 4.5g/L glucose. We conclude that the combination of metformin with gemcitabine has inappropriate effects for a successful treatment of pancreatic cancer. Thus, it might be more promising to use metformin in combination with other drugs that reduce the uptake or the metabolism of glucose.

KEYWORDS:

apoptosis; chemotherapy; microenvironment.; pancreatic adenocarcinoma