Hepatocellular cancer (HCC) is a disease of poor prognosis. Identifying novel molecular aberrations might present opportunities to identify new therapeutic targets. Due to the similarities between the processes of development and cancer, we used early developing livers to identify genes that might play a primary role in HCC. Platelet-derived growth factor receptor-α (PDGFRα) was identified from microarray using early developing mouse livers. Expression of PDGFRα and its upstream effectors, PDGF-AA and PDGF-CC, were examined in HCC tissues (n = 43) by Western blot, real-time PCR, and immunohistochemistry. Finally, effect of anti-PDGFRα antibody (mAb 3G3, ImClone Systems, Inc.) was examined on human hepatoma cells. A high expression of PDGFRα was observed during early liver development. HCCs (17 of 21) revealed cytoplasmic PDGFRα and activated PDGFRα (phospho-Tyr⁷⁵⁴) by immunohistochemistry. Additional HCCs (14 of 22) showed elevated PDGFRα levels when compared with the adjacent normal livers by Western blots. Of these 14 patients, 3 showed increased PDGFRα gene expression, 3 showed elevated PDGF-AA, and 4 had higher PDGF-CC levels in the tumors compared with adjacent livers. Multiple hepatoma cell lines, when treated with mAb 3G3, showed significant decreases in cell proliferation and survival (P < 0.05). In conclusion, ∼70% of HCC tissues had elevated PDGFRα levels due to diverse mechanisms. PDGFRα inhibition in hepatoma cells led to diminution of tumor cell survival and proliferation and thus might be of therapeutic significance. [Mol Cancer Ther 2007;6(7):1932–41]

Low-carbohydrate/high-fat diets (LC-HFDs) in rodent models have been implicated with both weight loss and as a therapeutic approach to treat neurological diseases. LC-HFDs are known to induce ketosis; however, systematic studies analyzing the impact of the macronutrient composition on ketosis induction and weight loss success are lacking. Male Wistar rats were pair-fed for 4 wk either a standard chow diet or one of three different LC-HFDs, which only differed in the relative abundance of fat and protein (percentages of fat/protein in dry matter: LC-75/10; LC-65/20; LC-55/30). We subsequently measured body composition by nuclear magnetic resonance (NMR), analyzed blood chemistry and urine acetone content, evaluated gene expression changes of key ketogenic and gluconeogenic genes, and measured energy expenditure (EE) and locomotor activity (LA) during the first 4 days and after 3 wk on the respective diets. Compared with chow, rats fed with LC-75/10, LC-65/20, and LC-55/30 gained significantly less body weight. Reductions in body weight were mainly due to lower lean body mass and paralleled by significantly increased fat mass. Levels of β-hydroxybutyate were significantly elevated feeding LC-75/10 and LC-65/20 but decreased in parallel to reductions in dietary fat. Acetone was about 16-fold higher with LC-75/10 only ( P < 0.001). In contrast, rats fed with LC-55/30 were not ketotic. Serum fibroblast growth factor-21, hepatic mRNA expression of hydroxymethylglutaryl-CoA-lyase, peroxisome proliferator-activated receptor-γ coactivator-1α, and peroxisome proliferator-activated receptor-γ coactivator-1β were increased with LC-75/10 only. Expression of phospho enolpyruvate carboxykinase and glucose-6-phosphatase was downregulated by 50–70% in LC-HF groups. Furthermore, EE and LA were significantly decreased in all groups fed with LC-HFDs after 3 wk on the diets. In rats, the absence of dietary carbohydrates per se does not induce ketosis. LC-HFDs must be high in fat, but also low in protein contents to be clearly ketogenic. Independent of the macronutrient composition, LC-HFD-induced weight loss is not due to increased EE and LA.

Mesenchymal stem cells from human bone marrow (hMSC) have the potential to differentiate into hepatocyte-like cells in vitro and continue to maintain important hepatocyte functions in vivo after transplantation into host mouse livers. Here, hMSC were differentiated into hepatocyte-like cells in vitro (hMSC-HC) and transplanted into livers of immunodeficient Pfp/Rag2^−/− mice treated with a sublethal dose of acetaminophen (APAP) to induce acute liver injury. APAP induced a time- and dose-dependent damage of perivenous areas of the liver lobule. Serum levels of aspartate aminotransferase (AST) increased to similar levels irrespective of hMSC-HC transplantation. Yet, hMSC-HC resided in the damaged perivenous areas of the liver lobules short-term preventing apoptosis and thus progress of organ destruction. Disturbance of metabolic protein expression was lower in the livers receiving hMSC-HC. Seven weeks after APAP treatment, hepatic injury had completely recovered in groups both with and without hMSC-HC. Clusters of transplanted cells appeared predominantly in the periportal portion of the liver lobule and secreted human albumin featuring a prominent quality of differentiated hepatocytes. Thus, hMSC-HC attenuated the inflammatory response and supported liver regeneration after acute injury induced by acetaminophen. They hence may serve as a novel source of hepatocyte-like cells suitable for cell therapy of acute liver diseases.

Objective: Liver regeneration is mainly based on cellular self-renewal including progenitor cells. Efforts have been made to harness this potential for cell transplantation, but shortage of hepatocytes and premature differentiated progenitor cells from extra-hepatic organs are limiting factors. Histological studies implied that resident cells in adult liver can proliferate, have bipotential character and may be a suitable source for cell transplantation. Methods: Particular cell populations were isolated after adequate tissue dissociation. Single cell suspensions were purified by Thy-1 positivity selection, characterised in vitro and transplanted in immunodeficient Pfp/Rag2 mice. Results: Thy-1⁺ cells that are mainly found in the portal tract and the surrounding parenchyma, were isolated from surgical liver tissue with high yields from specimens with histological signs of regeneration. Thy-1⁺ cell populations were positive for progenitor (CD34, c-kit, CK14, M2PK, OV6), biliary (CK19) and hepatic (HepPar1) markers revealing their progenitor as well as hepatic and biliary nature. The potential of Thy-1⁺ cells for differentiation in vitro was demonstrated by increased mRNA and protein expression for hepatic (CK18, HepPar1) and biliary (CK7) markers during culture while progenitor markers CK14, chromogranin A and nestin were reduced. After transplantation of Thy-1⁺ cells into livers of immunodeficient mice, engraftment was predominantly seen in the periportal portion of the liver lobule. Analysis of in situ material revealed that transplanted cells express human hepatic markers HepPar1 and albumin, indicating functional engraftment. Conclusion: Bipotential progenitor cells from human adult livers can be isolated using Thy-1 and might be a potential candidate for cell treatment in liver diseases.