Purpose: Preclinical model systems should faithfully reflect the complexity of the human pathology. In hepatocellular carcinoma (HCC), the tumor vasculature is of particular interest in diagnosis and therapy. By comparing two commonly applied preclinical model systems, diethylnitrosamine induced (DEN) and orthotopically implanted (McA) rat HCC, we aimed to measure tumor biology noninvasively and identify differences between the models.Experimental Design: DEN and McA tumor development was monitored by MRI and PET. A slice-based correlation of imaging and histopathology was performed. Array CGH analyses were applied to determine genetic heterogeneity. Therapy response to sorafenib was tested in DEN and McA tumors.Results: Histologically and biochemically confirmed liver damage resulted in increased 18 F-fluorodeoxyglucose (FDG) PET uptake and perfusion in DEN animals only. DEN tumors exhibited G1-3 grading compared with uniform G3 grading of McA tumors. Array comparative genomic hybridization revealed a highly variable chromosomal aberration pattern in DEN tumors. Heterogeneity of DEN tumors was reflected in more variable imaging parameter values. DEN tumors exhibited lower mean growth rates and FDG uptake and higher diffusion and perfusion values compared with McA tumors. To test the significance of these differences, the multikinase inhibitor sorafenib was administered, resulting in reduced volume growth kinetics and perfusion in the DEN group only.Conclusions: This work depicts the feasibility and importance of in depth preclinical tumor model characterization and suggests the DEN model as a promising model system of multifocal nodular HCC in future therapy studies.

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Chemokines remain attractive therapeutic targets for modulating inflammatory diseases in all areas of medicine including acute and chronic kidney disease. Industry has launched huge programs for the development of chemokine antagonists, and clinical trials with chemokine and chemokine receptor antagonists are ongoing. However, chemokine biology remains an area of unexpected discoveries. Here we discuss a number of questions which need to be addressed to further explore the potential of chemokine antagonism in renal inflammation: Why does renal expression of chemokines and chemokine receptors not always correlate with their functional significance? Why does chemokine antagonism only partially reduce renal leukocyte counts? Will antagonist combinations be more effective in reducing renal inflammation? What are the functional roles of homeostatic chemokines and atypical, nonsignaling chemokine receptors in renal inflammation? And finally, what classes of chemokine antagonists are available to address these questions experimentally?

The microvillus brush border on the renal proximal tubule epithelium allows the controlled reabsorption of solutes that are filtered through the glomerulus and thus participates in general body homeostasis. Here, using the lipid 5-phosphatase Ship2 global knockout mice, proximal tubule-specific Ship2 knockout mice, and a proximal tubule cell model in which SHIP2 is inactivated, we show that SHIP2 is a negative regulator of microvilli formation, thereby controlling solute reabsorption by the proximal tubule. We found increased PtdIns(4,5)P2 substrate and decreased PtdIns4P product when SHIP2 was inactivated, associated with hyperactivated ezrin/radixin/moesin proteins and increased Rho-GTP. Thus, inactivation of SHIP2 leads to increased microvilli formation and solute reabsorption by the renal proximal tubule. This may represent an innovative therapeutic target for renal Fanconi syndrome characterized by decreased reabsorption of solutes by this nephron segment.

and its different differentiation steps. Finally, we identified a role of osteocalcin in mineralized nodules production and for the MEK-Erk1/2 signaling pathway in the OPS phenotype.