|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1999 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1998 : ¥1,000,000 (Direct Cost : ¥1,000,000)
We analyzed molecular mechanisms of paclitaxel action on CDDP resistant ovarian cancer cells on the basis of bcl-2 expression and phosphorylation, and apoptotic cell death.
We measured IC50 by MTT assay when treated with CDDP and paclitaxel using ovarian cancer cell lines TYK, Nakajima, and HRA, and their CDDP-resistant lines TYK-R, Nakajima-R, and HRA-R. Two of the 3 CDDP resistant lines turned out to be sensitive to paclitaxel, however, only HRA-R showed resistance to paclitaxel. When treated with CDDP and paclitaxel, DNA fragmentation was observed on agarose gel electrophoresis, revealing apoptotic cell death. We also analyzed mRNA expression of bcl-2 and p53 by RT-PCR, and protein expression by Western blotting. In the 3 CDDP resistant lines, bcl-2 expression was increased, and p53 expression was decreased both in mRNA and protein level. Although we did riot observe the phosphorylation of bcl-2 by the treatment of CDDP, paclitaxel treatment of the parental cell lines clearly induced the phosphorylation of bcl-2. On the other hand, bcl-2 phosphorylation on paclitaxel sensitive TYK-R, and Nakajima-R was shown by the treatment of paclitaxel, however, on paclitaxel resistant HRA-R, even 10 μM of paclitaxel was unable to induce the phosphorylatisn of bcl-2. These data raise the possibility of the mechanism by which paclitaxel treatment induce the phosphorylation of bcl-2 and lead to apoptolic cell death in CDDP resistant cells.