Sensitization And Effect On Multidrug Cancer Cells From TmSm On Breast Cell Lines And Its Molecular Mechanism

Cancer is one of the biggest threatened for human health, chemotherapy is the main method to treat cancer currently. The change of cancer structure and mechanism induce failure of cancer treatment, which because of internal and external environment changes due to genetic factors or chemotherapeutic agents. The chemotherapy induced tumor cells death is largely depending on activation of apoptosis, so most cancer treatments focus on targeting the apoptosis gene or protein. Target molecular therapy can't be used as curative treatment due to it's limitation, but always used to combine with traditional treatment (radiotherapy or chemotherapy), the synergy promotes comprehensive cancer treatment, improve chemotherapy efficacy, low toxicity, and become an important treatments.Survivin has been implicated inhibiting apoptosis, playing a key role in cell division, selectively expressing in transformed cells and most human cancers, been seem as a target of cancer diagnose, and contributing to multidrug resistance of chemotherapy and radiotherapy. Based on the above, survivin is seemed as one of most important target for anticancer. The fusion protein TmSm was using a phosphorylation-defective survivin Thr34â†'Ala mutant surviving (T34A), that prevented phosphorylation of the endogenous survivin to advance apoptosis, and show little toxicity or non-toxicity. This study use TmSm combined with doxorubicin to do further research about their effect and mechanism.This study firstly used MTT to test the inhibition of TmSm, doxorubicin and TmSm-doxorubicin on breast cancer cells in 48h, and then used SPSS to analysis the 50% inhibiting concentration (IC50). We chose the most sensitive cell lines to TmSm, MCF-7 which IC50 declined 47.2%, to do further research. Then used Annex-V-FITC/PI to test TmSm synergistic effect on doxorubicin, then check the TmSm effect on cell cycle, it was proved TmSm has little effect about 5% on cell cycle. The western-blot result showed a decrease of Bcl-2, and an obvious increase in apoptosis protein, such as cleavage of PARP and caspase-9. Furthermore, this study tested TmSm combined doxorubicin effect on doxorubicin-resistance cell line, MCF-7/ADM. Through MTT and analysed by SPSS, we found TmSm combined doxorubicin effect was little changed in inhibition, the effect was only 1.4 fold compared with doxorubicin lonely. Followed these results we test the effect by Annexin V-FITC/PI and Rhol23 experiment, we suppose that TmSm just improve the chemotherapy sensitivity, the P-gp expression has not changed according to western-blot.We conclusion that the sensitization effect of TmSm on doxorubicin inducing apoptosis in human breast cancers was obvious, and might not potentiate the ability of doxorubicin through G2/M arrestting to synergistic apoptosis. As shown in western-blot it has a synergistic decrease through caspase and bcl-2 pathway, which may potentially reduce tumor apoptosis. But when we done this on MCF-7/ADM, there was no multidrug reverse, the resistance index (RI) was 1.485 fold,1.416 fold and 1.318 fold in 24h,48h,72h respectively, only sensitive effection. In conclusion, combined use of TmSm and doxorubicin, increased the susceptibility of breast cancer to doxorubicin mainly by apoptosis pathway.