Growth Inhibition Effects Of DADS On Human Small Cell Lung Cancer Cells H446 In Vivo And In Vitro

Objective:To observe the effects of DADS on the growth of human small cell lung cancer H446 cells in vivo and in vitro.Methods:H446 cell lines were cultured in vitro.Cell proliferation inhibition was measured by MTT assay,growth curve analysis and average doubling time.Cell morphologic changes were observed by optics microscope(HE staining)and fluorescence microscope(AO-EB staining and Hoechst 33258 staining).Animal models were constructed on BALB/c nude mice with subcutaneously transplanted SCLC H446.The nude mice bearing with SCLC H446 were divided into 5 groups by random selection,which were treated with NS or DDP or with different doses of DADS(20μg/ml,60μg/ml,180μg/ml,im.Qod for ten times).The human SCLC H446 cells were implant into the right axial regions of nude mice.The dimensions of xenografts were measured and the living states of nude mice with SCLC H446 were observed.The xenograft tumor growth in mice was observed after treated with DADS in vitro and intraperitoneal injection of DADS.The morphological changes of the tumors were examined under light microscopy.Phase distribution of xenograft cell cycle was analyzed by flow cytometry(FCM).Expression of proliferating cell nuclear antigen (PCNA)in every group xenograft was determined by immunohistochemical staining.Results:MTT assay showed that DADS from 4 to 60μg/ml significantly inhibited H446 cells and exhibited a dose-dependent and time-dependent model.After exposure to DADS, H446 cell average doubling time retarded from 25.40 hours in normal cultured cells to DADS experimented H446 cells 145.64 hours(P＜0.05).Under inverted microscope,optics microscope and fluorescence microscope,H446 cellular heteromorphism diminished, nucleocytoplasmic proportion was reliable to reasonableness,cellular apparatus was abundant in plasm,nuclear and partial cell organs manifest retrograde alters.All these showed above suggested that H446 cells malignancy and proliferation capacity was declined because of DADS treatment.DADS at every group could inhibit the growth of xenograft in nude mice with SCLC H446(P＜0.05).When the dose of DADS were 20 mg·kg^-1,60 mg·kg^-1and 180 mg·kg^-1,the tumor growth was significant inhibition the inhibiting rates on tumor were 40.6%,53.1%and 66.4%,and inhibition expression of PCNA protein in implanted tumor.Flow cytometry analysis revealed that treating xenograft tumor cells with increasing quantities of DADS increased the percentage of cells in the G₂/M phase.The results of immunohistochemical staining of PCNA showed that PCNA label index of group NS was the highest.There was no significant difference among the rest groups.Conclusion:1.DADS could significantly inhibit the proliferation of human small cell lung cancer cell lines H446 and this effect presents a scene of dose-dependent and time-dependent,2.DADS could obviously inhibit the growth of xenograft of H446 cells in nude mouse.3.DADS inhibited proliferation and induce apoptosis of xenograft tumor cell by preventing the G₂/M phase arrest.4.Anti-proliferation mechanism probably related to down regulated expression of PCNA protein in xenograft.