Liver metastases provide a valuable model for studying metastatic invasion. This thesis aimed to analyze gene expression profiles and identify genes related to metastasis and invasion in liver metastasis models. Differential gene expression was assessed using a syngeneic mouse model (CT26/Balb/C), a xenograft model (LS174T/nude mouse), and five clinical specimens. The analysis of gene expression in both the syngeneic mouse model and human specimens suggested that the entire invasion front should be evaluated to discover overlapping target genes. Global studies on the host's invasion front indicated significant overexpression of hepatic stellate cell activation markers, demonstrating the effectiveness of a genome-wide differential gene expression approach. Investigating tumor cells in vitro, in vivo, and at the invasion front revealed increased cellular specialization. Notably, β-catenin gene expression was elevated 9.6-fold at the invasion front compared to in vitro conditions. Promoter activity analysis showed an 18.4-fold increase in β-catenin transcription in invasion front tumor cells versus those in the tumor's inner regions, indicating a transcriptional regulatory mechanism alongside known post-translational ones. Overall, high-throughput oligonucleotide microarray analysis combined with real-time PCR facilitated the identification of genes implicated in proliferation, invasion, and angiogenesis in colorectal liver metas
