The Expression of Bcl-2, Bax, Cytochrome C and Caspase-3 in Camptothecin-Induced Apoptosis of Mouse 3T3 Fibroblasts

ABSTRACT

BACKGROUND: Camptothecin (CPT), which has been used for cancer treatment and apoptosis as an inhibitor of DNA topoisomerase I. We investigated the possibility that camptothecin induces anti-appoptotic bcl-2 and pro-apoptotic bax, cytochrome c and caspase-3. METHODS: We performed immunocytochemical stains for bcl-2, bax and cytochrome c, and also performed westem blots for caspase-3 and the three proteins above using mouse 3T3 fibroblasts treated with CPT (0.5 microgram/mL). The immunostain for bcl-2 was done 12 hours after a microinjection of antisense oligomer to bcl-2 in the nuclei of the cells. RESULTS: On immunocytochemistry, bcl-2 showed no expressions regardless of CPT treatment and microinjection of the antisense oligomer. The expression of cytochrome c was not changed before and after CPT treatment, and bax demonstrated weak or moderate expressions at 36 and 48 hours afte the treatment. There were no expressions at 0, 12, and 24 hours after CPT treatment. On westem blot, bcl-2 exhibited no expressions before and after CPT treatment. Expressions of ctyochrome c and caspase-3 increased after CPT treatment, and expressions of bax decreased 24 hours after CPT treatment followed by a tendency of increased expressions as time went by. CONCLUSIONS: In the CPT-induced apoptosis of mouse 3T3 fibroblasts, CPT induced increased expressions of bax, cytochrome c and caspase-3 with no expressions of bcl-2, which are associated with the apoptosis pathway.