Carcinoma Metastasis-An Approach to Models

Background: Epithelium is separated from other tissues in the body by the basal membrane. When respecting this boundary, atypical epithelial growth does not cause serious illness in most cases. Therefore, carcinoma in situ is considered to be a non-malignant condition. However, the situation is quite different if the epithelial cells do not respect the natural boundaries in the tissue, a condition that is often referred to as cancer. Uncontrolled invasive growth is indeed the main characteristic of malignancy, and metastasis is in most cases the reason why cancer patients die. Materials and methods: The purpose of this article is to highlight how carcinoma cells, nature, can be classified in three steps, in respect to the first local infiltration of malignant epithelium. The literature referred to is selected on the basis that the views advocated are not controversial, and not represent individual findings. Moreover, some considerations are based on the authors own experience in clinical and molecular basic research. Results: The main characteristics of invasive cellular behavior are modified adhesion and a transition from fixed cells to a migratory phenotype. Invasion is made possible by the degradation of extracellular components. We only know fragments of the gene and phenotypic changes that enable cancers origin of behavior, but there is evidence that chemokines play a central role in the directional spread of motile cells. However, the most common characteristic of carcinoma cells is their loss of cell polarity. Interpretation: The complexity of multicellular organisms is staggering. Artificial and highly simplified model systems are therefore cancer researcher’s most important tools. To be significant, such results must be translated and verified to the in vivo situation. In addition, generality in cancer research finding must be given greater importance, since individual results, not can form the basis for new treatment regimes. Today’s biggest challenge for researchers is therefore to be able to collate the enormous diversity of molecular biological knowledge that daily runs.