[Cancer metastasis and oncogenes]

Alterations in the structure and/or expression of oncogenes have been examined to comprehend better the relationship between metastasis and oncogenes. There are reports that amplification and overexpression of N-myc (human neuroblastoma) and erbB-2 (human breast cancer) are closely related to malignant progression. On the other hand, DNA transfer experiments have also been done to assess involvement of oncogenes in metastasis. The active ras oncogenes, which are frequently used, show that transfer of the ras oncogenes endow and/or enhance the metastatic potential of the recipient cells. In addition to the phenomenological studies to determine whether an oncogene alters metastatic potential, increasing attention has been directed to possible phenotypic changes relating to metastasis and affected by oncogenes. It has been clarified that transfer of a certain oncogene, such as ras and fos, alters the expression of biomolecules, for example, metalloproteinases responsible for invasion, autocrine motility factors and cytoskeletal proteins related to cell motility, receptors of fibronectin for cell attachment, and histocompatibility antigens, such as H-2K and H2-D. While further characterization of the biomolecular changes induced by the oncogenes has to be done, the mechanisms of alteration in the expression and function of biomolecules directly involved in the metastatic potential also should be paid attention.