|In the course of carcinogenesis, cells acquire a number of genetic changes most of which may have no effect on cellular function. There are, however, critical genetic alterations that affect two classes of genes: oncogenes that are activated or altered in function; and tumor suppressor genes that are down-regulated or ablated in cancer cells.
Discovery and analysis of tumor suppressor genes have contributed to a better understanding of the molecular basis of breast cancer development. Studies on BRCA1 and BRCA2 tumor suppressor genes have provided useful information for understanding familial breast cancer. Other tumor suppressor genes are involved in sporadic breast cancer including PTEN and p53. However, it is likely that many, if not most, tumor suppressor genes responsible for sporadic breast cancer remain to be discovered. We have discovered that DBC2 suffers genetic alterations that affect its function in ways that suggest that it is a tumor suppressor gene. It is important to clarify the role of these alterations in breast cancer development because DBC2 may have the same impact on sporadic breast cancers as BRCA1 and BRCA2 did on hereditary cancers.