[Molecular mechanisms of breast cancer progression]

Breast carcinoma is considered to occur as non-invasive carcinoma (DCIS) and to progress to the stage of invasive cancer. In DCIS, multiple gene and chromosome alterations are shown to occur already, and the pattern of alterations are concordant between DCIS and invasive components in most of individual tumors. Therefore, unknown molecular alterations are considered to exist that are involved in tumor invasion. A lot of alterations are also shown to occur in breast cancer cells, e.g., overexpression of growth factor receptors, cyclins and the molecules regulating cell-cycle, and cell-adhesion molecular. Clarification of signal-transducing mechanism of these molecules in cells and alterations of the system in cancer cells will be important as molecular mechanism of proliferation and progression of breast cancer. It is expected that the therapeutic strategy targetted to the control of these molecular events is developed in future.