| Tumor cells have the characteristic of rapid proliferation..Microtubules,as a part of the cytoskeleton,play an important role in regulating cell proliferation. Because of the proliferation rate of tumor cells is much higher than normal tissue cells,the inhibition of microtubules could effectively suppress the growth of tumor cells.18B,developed and screened by the coopration of our lab and Institute of pharmacology & toxicology of AMMS. Preliminary studies had proved that 18B can competitively bind at the colchicine site of tubulin and promote microtubule depolymerization.In our study,we’ll use experiments in vitro and in vivo to investigate the anti-tumor effect of 18B.The MTT assay results showed that 18B can effectively inhibit the 12 kinds of different tumor cell proliferation with dose-response relationship.The repeat results are consistent.The IC50 range are between 0.091～1.049nM,the Imax are 53.41%～95.05%. Compared with the positive control drug paclitaxel, the inhibition of different tumor cell proliferation by 18B is roughly equal and even stronger. And by the detection of flow cytometry,18B can induce BGC-823 cells in the early and late apoptosis.In the concentration of 8nMafter 24h,the percentage of apoptotic could reach about 66.45%; 18B also induce the decline of mitochondrial membrane potential of BGC-823 cells and finally induce the cell cycle arrest in G2/M of BGC-823 and HT-29.The Hoechst 33342 staining showed the result of nuclear fragmentation.18B can increase the expression of BAD and TNF-α while inhibit the expression of BCL-2,Survivin,TGF-β and CDK1.The results of animal study showed that 18B can significantly inhibit the growth of S180,BGC-823 and H460 cells in subcutaneous xenografts. In the S180 cell subcutaneous xenograft, the tumor weight inhibition rate range of the 3 treatment group are 28.39%-72.62% without animal death.And in the BGC-823 cell subcutaneous xenograft,the tumor weight inhibition rate range of the 3 treatment group are 24.77%-77.32%.The H&E staining and Immunohistochemistry results could also reflect the 18B effect. In the H460 cell subcutaneous xenograft, the tumor weight inhibition rate range of the 3 treatment group are 17.76%-61.90%.In summary,18B can induce apoptosis and cycle arrest of tumor cells by regulate several genes while significantly inhibit tumor growth in vivo of S180, BGC-823 and H460 cells.Recently research showed that the old urinary antibiotic nitroxoline have the potent activities of inhibiting angiogenesis,inducing apoptosis,and blocking cancer cell migration and invasion..This make nitroxoline have the potential to became an anticancer drug.Drug repurposing,a newly strategy to develop anticancer drugs,is a way to screen new use from old drugs.The major advantage of this approach is that the safety profiles and pharmacodynamics property of old drugs are in general well known due to the clinical history.In our study,the major method to perform the systemic preclinical evaluation of nitroxoline for anticancer effect is to establish orthotopic kidney and bladder tumor models. The orthotopic kidney tumor model was created by seeding kidney tumor tissue mass and the bladder wall was explosed to tumor cell suspension after mechanical damage to establish the orthotopic bladder tumor model.The MTT assay results showed that nitroxoline inhibit the growth of several cell lines in a dose-dependent manner.The inhibit effect reached about 75%-99% at the maximum concentration of 80μM.In addition, the metabolite nitroxoline sulfate also showed anticancer activity,but with -30% decreases in maximum inhibition rates.Nitroxoline effectively and dose-dependently inhibited the growth of urological tumors in orthotopic mouse models.The inhibition rate reached about 46%-85% without corresponding increase in toxicity.Taken together,our study incate that nitroxoline is a potential inhibitor of tumor growth and has been approved to enter into Phase Ⅱ clinical trial in China. |
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