The mean combination index for the combination of a TEA DOXO was 0. 41 0. 07 and 0. 53 0. 05 for MDA MB 231 and BT 20 cells, respectively. The mean combination index for the combination of a TEA CDDP was 0. 45 0. 10 and 0. 75 0. 08 in MDA MB 231 and BT 20 cells, respectively. These data demonstrate that combinations of a TEA DOXO or a TEA CDDP synergistically induce apoptosis Ivacaftor in both cell lines. Wes tern blot analyses show that a TEA at 20 uM coop erates with DOXO and CDDP to induce elevated levels of cleaved caspase 8, caspase 9, and PARP in both cell lines, indicating that apoptosis induced by these combinations involves both Inhibitors,Modulators,Libraries caspase 8 and caspase 9 activation.

p73 protein level is upregulated by a TEA DOXO or a TEA CDDP combinations and is involved in combination induced apoptosis Since DOXO and CDDP Inhibitors,Modulators,Libraries as well as a TEA have been shown to induce p73 upregulation in breast cancer cells, the combination of a TEA DOXO or a TEA CDDP was investigated for ability to coopera tively enhance p73 protein expression. Single treat ments with DOXO, CDDP or a TEA at sub apoptotic levels for 24 hours slightly increased p73 protein expression above control levels, whereas combinations at the same levels markedly enhanced p73 protein expression in comparison with single treatments in both MDA MB 231 and BT 20 cells. siRNA to p73 significantly reduced the ability of com bination treatments to induce apoptosis as determined by annexin V and PARP analyses in MDA MB 231 cells. Western blot data show that siRNA to p73 effectively silenced p73 protein expression.

These data indicate that p73 Inhibitors,Modulators,Libraries activation by combination treatments is critical for induction of cell death by apoptosis. Combinations of a TEA DOXO or a TEA CDDP upregulate pro apoptotic and downregulate anti apoptotic Inhibitors,Modulators,Libraries mediators at both mRNA and protein levels Published data show that p73 can regulate p53 depen dent genes in p53 deficient cells. To better under stand the cellular events involved in p73 mediated apoptosis in combination treatments, mRNA and pro tein expression of p53 mediated Inhibitors,Modulators,Libraries pro apoptotic mediators DR5, Fas, Bax, and Noxa, and anti apoptotic selleck chemicals mediator Bcl 2 were examined. Combinations of a TEA DOXO or a TEA CDDP enhanced DR5, Fas, Bax and Noxa mRNA and protein expression, and decreased Bcl 2 mRNA and protein expression in MDA MB 231 and BT 20 cells. siRNA knockdown of p73 was performed to deter mine whether expression levels of these mediators were regulated by p73. siRNA to p73 in MDA MB 231 cells DR5, Fas, Bax and Noxa, and to decrease the level of Bcl 2.