The development of hepatocellular carcinoma (HCC) is a multistep process associated with changes in host gene expression, some of which correlate with the appearance and progression of tumor. Preneoplastic changes in gene expression result from altered DNA methylation, the actions of hepatitis B and C viruses, and point mutations or loss of heterozygosity (LOH) in selected cellular genes. Tumor progression is characterized by LOH involving tumor suppressor genes on many chromosomes and by gene ampli®cation of selected oncogenes. The changes observed in di erent HCC nodules are often distinct, suggesting heterogeneity on the molecular level. These observations suggest that there are multiple, perhaps redundant negative growth regulatory pathways that protect cells against transformation. An understanding of the molecular pathogenesis of HCC may provide new markers for tumor staging, for assessment of the relative risk of tumor formation, and open new opportunities for therapeutic intervention.

Angiogenesis, the formation of new blood vessels, is essential for tumor growth, progression and metastasis. The development of agents that target tumor vasculature is ultimately dependent on the availability of appropriate preclinical screening assays. The chorioallantoic membrane (CAM) assay is well established and widely used as a model to examine angiogenesis, and anti-angiogenesis. This review 1) summarizes the currently used angiogenesis assays and the importance of CAM model among them; 2) summarizes the current knowledge about the development and structure of the CAM's capillary bed; 3) reports findings regarding the role played by molecular signaling pathways in angiogenesis process; 4) discusses the use, advantages and limitations of the CAM as a model for studying tumor angiogenesis and invasiveness, as well as development of angiogenic and/or anti-angiogenic agents; 5) discusses the importance of standardization of the major methodologies for all aspects of the use of the CAM in angiogenesis-related studies; 6) and finally, summarizes major findings regarding the agents developed by the use of CAM model in the study of tumor angiogenesis, invasion and development of anti-angiogenic agents.

The integration of stem cell technology and cell sheet engineering improved the potential use of cell sheet products in regenerative medicine. This review will discuss the use of mesenchymal stem cells (MSCs) in cell sheet-based tissue engineering. Besides their adhesiveness to plastic surfaces and their extensive differentiation potential in vitro, MSCs are easily accessible, expandable in vitro with acceptable genomic stability, and few ethical issues. With all these advantages, they are extremely well suited for cell sheet-based tissue engineering. This review will focus on the use of MSC sheets in osteogenic tissue engineering. Potential application techniques with or without scaffolds and/or grafts will be discussed. Finally, the importance of osteogenic induction of these MSC sheets in orthopaedic applications will be demonstrated.

The generation of urothelial carcinoma is caused by the accumulation of various molecular changes, as in most malignancies. There are conflicting data about the status of HER-2/neu oncogene in urothelial carcinomas. The aim of this study was to determine the status of HER-2/neu oncogene in high-grade invasive urothelial carcinoma of urinary bladder both in protein and DNA level. We evaluated HER-2/neu protein overexpression by immunohistochemistry (IHC) and gene amplification by fluorescent in situ hybridization (FISH) and real-time quantitative PCR in paraffin-embedded samples of high-grade invasive urothelial carcinoma obtained from 36 patients. Polysomy 17 was also assessed by FISH. Immunohistochemically, HER-2/neu protein overexpression was observed in 22 (61.1%) tumors (ten tumors with score 3+ and 12 with score 2+). Fourteen of 36 tumors (38.9%) were evaluated as negative (score 0 or 1+). Complete concordance between FISH and the PCR was seen in all of the samples scored as 0 and 1+ by IHC. HER-2/neu gene amplification was observed in three of 27 (11.1%) tumors by FISH (nine samples were non-informative) and in eight of 36 (22.2%) tumors by the PCR. The complete concordance between HER2-2/neu protein overexpression and gene amplification was seen only in three of 27 tumors. Polysomy 17 was seen in nine tumors (33.3%). The results indicated that, in contrast to breast cancer, there was no strong association between HER-2/neu overexpression and gene amplification in invasive urothelial carcinomas, and polysomy 17 was higher in tumors showing HER-2/neu overexpression.

Epidemiologic studies have identified a close link between chronic hepatitis B virus (HBV) infection and the development of hepatocellular carcinoma (HCC). 1,2 The most important risk factors for the development of HCC are the carrier state, characterized by persistent virus gene expression and replication, and the presence of chronic liver disease, which often progresses from active hepatitis to cirrhosis.

Under most circumstances, hepatitis B virus (HBV) is noncytopathic. However, hepatocellular regeneration that accompanies each bout of hepatitis appears to be associated with increased integration of HBV DNA fragments expressing the virus encoded hepatitis B x antigen (HBxAg). Intrahepatic HBxAg staining correlates with the intensity and progression of chronic liver disease (CLD), and additional work has shown that HBxAg blocks immune mediated killing by Fas and by tumor necrosis factor alpha (TNFα). This is not only associated with the blockage of caspase activities by HBxAg, but also by the constitutive stimulation of hepatoprotective pathways, such as nuclear factor kappa B (NF-κB), phosphoinositol 3-kinase (PI3K), and beta-catenin (β-catenin). HBxAg also appears to promote fibrogenesis, by stimulating the production of fibronectin. HBxAg also stimulates the production and activity of transforming growth factor beta 1 (TGFβ1) by several mechanisms, thereby promoting the profibrogenic and tumorigenic properties of this important cytokine. In addition, HBxAg appears to remodel the extracellular matrix (ECM) by altering the expression of several matrix metalloproteinases (MMPs), which may promote tumor metastasis. Hence, HBxAg appears to promote chronic infection by preventing immune mediated apoptosis of infected hepatocytes, by promoting the establishment and persistence of fibrosis and cirrhosis preceding the development of HCC, and by promoting the remodeling of EMC during tumor progression.

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