Inducible protein in rat hepatomas with expression alternative to alpha-fetoprotein

From whole body to cellular models of hepatic triglyceride metabolism: man has got to know his limitations

The liver is a main metabolic organ in the human body and carries out a vital role in lipid metabolism. Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, encompassing a spectrum of conditions from simple fatty liver (hepatic steatosis) through to cirrhosis. Although obesity is a known risk factor for hepatic steatosis, it remains unclear what factor(s) is/are responsible for the primary event leading to retention of intrahepatocellular fat. Studying hepatic processes and the etiology and progression of disease in vivo in humans is challenging, not least as NAFLD may take years to develop. We present here a review of experimental models and approaches that have been used to assess liver triglyceride metabolism and discuss their usefulness in helping to understand the aetiology and development of NAFLD.

Increased efficacy and safety in the treatment of experimental liver cancer with a novel adenovirus-alphavirus hybrid vector

An improved viral vector for cancer gene therapy should be capable of infecting tumors with high efficiency, inducing specific and high-level expression of transgene in the tumor and selectively destroying tumor cells. In the design of such a vector to treat hepatocellular carcinoma, we took advantage of (a) the high infectivity of adenoviruses for hepatic cells, (b) the high level of protein expression and proapoptotic properties that characterize Semliki Forest virus (SFV) replicon, and (c) tumor selectivity provided by alpha-fetoprotein (AFP) promoter. We constructed a hybrid viral vector composed of a helper-dependent adenovirus containing an SFV replicon under the transcriptional control of AFP promoter and a transgene driven by SFV subgenomic promoter. Hybrid vectors containing murine interleukin-12 (mIL-12) genes or reporter gene LacZ showed very specific and high-level expression of transgenes in AFP-expressing hepatocellular carcinoma cells, both in vitro and in an in vivo hepatocellular carcinoma animal model. Infected hepatocellular carcinoma cells were selectively eliminated due to the induction of apoptosis by SFV replication. In a rat orthotopic liver tumor model, treatment of established tumors with a hybrid vector carrying mIL-12 gene resulted in strong antitumoral activity without accompanying toxicity. This new type of hybrid vectors may provide a potent and safe tool for cancer gene therapy.

Cellular aspects of alpha-fetoprotein reexpression in tumors

The cellular basis of AFP synthesis in normal development, liver regeneration, hepatocarcinogenesis and in tumors is discussed in the review. The attempt is made to interpret the production of AFP by germ cell and liver tumors as a consequence of their origin from the cell types producing AFP in normal conditions. Thus, AFP in germ cell tumors is explained by the development of the yolk sac visceral endoderm (YSVE) in teratocarcinomas, since YSVE is the first site of AFP synthesis in the embryo. The next site of AFP production is embryonal hepatoblast and just hepatoblastomas are the maximal producers of AFP among liver cancers. The reason for AFP resumption in hepatocellular carcinomas (HCC) is not yet clear. This problem is discussed in the light of possible role of oval cells in the HCC origin and the concept of the two states of the mature hepatocyte, associated and non-associated with AFP production. The crucial role of extracellular matrix in the control of AFP-producing state of hepatocyte is emphasized.