INDUCTION OF APOPTOSIS BY TUMOR-SUPPRESSOR GENES AND ONCOGENES

The p53 tumor suppressor gene product and the bcr-abl, bcl-2, and c-myc gene products all appear to influence the susceptibility of cells to apoptosis. In addition to the role p53 protein plays in mediating a cell cycle arrest in G1 following DNA damage, p53 also performs functions critical for removal of damaged cells by initiating apoptosis in certain physiological situations. Cells which express deregulated c-myc are sensitized to apoptosis following various growth suppressing stimuli and these observations have provided new insights into how apoptosis-suppressing genes such as mutant p53, bcl-2 and bcr-abl may cooperate during transformation and how they might influence the sensitivity of cells to radiation and chemotherapy.