Effects Of YM155 On Biological Behavior In Osteosarcoma Via Inhibiting Expression Of Survivin

By the means of the significance of surviving and its inhibitor YM155 intumor biology behavior, we further investigate the application of YM155 intreatment of osteosarcoma via using immunology, gene and molecular biology method. This research could be divided into three parts:Expression and clinical significance of Survivin in osteosarcomaSurvivin, a member of the apoptosis inhibiting factor family latest reported, highly expresses in tumor cells but not in mature organization,and thus aroused researcher’s wide attention. In this study, expression of survivin was determined using q RT-PCR and immunohistochemical staining in tumor tissues and para-tumor normal tissues collected from 31 patients with osteosarcoma.Results showed that survivin m RNA and protein expression were significantly higher in osteosarcoma than in the normal tissues. Expression of survivin in three kinds of osteosarcoma cell line cells(Saos-2, MG63 and U2OS) and the osteogenesis cell line h HFOB1.19 cells was alsodeter mined through the q RT-PCR and Western blot test.Results showed that m RNA and protein levels of survivin in the Saos-2, MG63 and U2 OS cells were significantly higher than in h HFOB1.19 cells. Further study was carried out to evaluated the correlation between the expression of survivin andthe Ki67 score. The results showed that Ki67 score in patients with high expression of survivin was significantly higher than in that with low expressionof survivin.Moreover, high expression of survivin predicted significantly shortersurvival time than low survivin expression in osteosarcoma patients.These results suggest that survivin was highly expressed in osteosarcoma patients, and was associated with tumor malignant degree and prognosis of disease, suggesting that survivin can be used as a potential gene targets for clinical treatment of osteosarcoma.Effect of YM155 on proliferation, apoptosis and invasion inHuman osteosarcoma YM155, a novel small-molecule inhibitor ofsurvivin, is known to exert antitumor effects on variouscancers, including breast, prostate and lung cancer. However,there are few studies describing the inhibitory effect of YM155 on human osteosarcoma(OS) which highly expresses survivin.Here, we tested the effects of YM155 on OS cells by severalin vitro experiments. It was found that YM155 inhibitedcell proliferation,colony formation, migration and invasion,induced cell apoptosis, as well as increased caspase-3,-8 and-9 activity in the OS cell lines in a dose-dependent manner.In addition,YM155 also inhibited surviving expression in xenograft tumorinadose-dependentmanner, and thussuppressed tumor growth in vivo, reducing the size of OSMG63 cell xenografts. Taken together, the findings revealedthat YM155 suppresses the tumor growth of OS in vitro andin vivo, suggesting that YM155 has potential as a therapeuticagent for the treatment of OS.Effects of YM155 on sensitivity of osteosarcoma to doxorubicin Doxorubicin(DOX) is one of the widely used chemotherapeutic drugs for the treatment of human osteosarcoma(OS). However, acquisition of DOX resistance is common in patients with OS, leading to local and distantfailure. In this study, we demonstrate that survivin expression is significantly upregulated in OS primary tumors compared to paired normal tissue. In addition, survivin expression was further increased inDOX resistant cells(MG63/DOX) as compared to its parent cells(MG63).Thus, we hypothesize that targeting of survivin in OS could reverse the DOX resistant phenotype in tumor cells thereby enhancing the therapeutic efficacy of DOX. We test the efficacy of YM155, a small molecule survivin inhibitor, either as a single agent or in combination with DOX in vitro and in vivo.We found that combination treatment of YM155 and DOX in DOX resistant cells(MG63/DOX) could significantlyinhibited cell proliferation and colony formation, induce cell apoptosis and promoted caspase-3,-8, and-9 activity invitro, and promoted tumor regression in established OS xenograft models. We also found that YM155 suppressed Mcl-1 and survivin expression without affecting the expression of anti-apoptotic proteins X-linked inhibitor of apoptosis(XIAP) and Bcl-2. In addition, YM155 decreased phosphoinositide 3-kinase(PI3K) and AKT expression without effecting total PI3 K and AKT in the OS cell lines.Taken together, the evidence presentedhere supports the favorable preclinical evaluation that YM155 could overcome DOX the resistance in tumor cells throughsuppressing PI3K/AKT pathway, andthereby enhancing the effectiveness of DOX in OS, suggesting that YM155 in combination with DOX has potential inthe treatment of osteosarcoma.