| Object:Recombinant endostatin is proved to be effective in tumor angiogenesis inhibition.Additionally,the anti-tumor effect is enhanced when Recombinant endostatin combined with chemotherapeutic drugs.In this study,we observed the tumor inhibition effect of recombinant vascular endostatin combined with gemcitabine in different administration sequences on Lewis lung xenograft carcinoma,to determine the optimal dosing sequence about the combined therapy of Recombinant endostatin and chemotherapy,at the same time,to explore the mechanism of combined therapy.Methods:Lewis lung carcinoma xenograft model was established.Next 72 tumor-bearing mice were divided into 6 groups randomly,and there are 12 mice in each group.Treatment groups were as follows:the control group was administrated with 0.2 ml of 0.9%normal saline by intraperitoneal injection from the 1st day to the 14th day;Endostar alone group was administrated with endostar of 10mg/kg/d by intraperitoneal injection from 1st day to the 14th day;gemcitabine alone group was administrated with gemcitabine of 30mg/kg on the dl and d8 by intraperitoneal injection;Endostar first group was administrated with endostar of 10mg/kg/d by intraperitoneal injection from 1st day to the 14th day and administrated with gemcitabine of 30mg/kg on d5 and d12 by intraperitoneal injection;Gemcitabine first group was administrated with endostar of 10mg/kg/d by intraperitoneal injection from 2nd day to the 15th day and was administrated with gemcitabine of 30mg/kg on d5 and d12 by intraperitoneal injection;Simultaneous group was administrated with endostar of 10mg/kg/d by intraperitoneal injection from 1st day to the 14th day and was administrated with gemcitabine of 30mg/kg on dl and d8 by intraperitoneal injection.The tumor volume of each group was measured every other day,and the tumor growth curve was drawn.The small animal 18F-FDG PET/CT scan was used to detect the SUVmax of each group of tumor tissues.The oxygen microelectrode was used to measure the tumor oxygen partial pressure of the 5th,10th and the 15th day after treatment.The cell cycle distribution of tumor tissues in each group was performed by flow cytometry after the treatment.The expression levels of Vascular endothelial growth factor(VEGF)and alpha smooth muscle actin(a-SMA)of each group were detected by immunohistochemistry.In addition,heart,liver,lung,kidney,and spleen tissues were removed after treatment and examined by HE staining for observeing the toxicity of the organs in each group.Results:1.Tumor growth curve:the growth of tumors in the gemcitabine alone group,the endostar first group,the gemcitabine first group,and the simultaneous group were slower than that of the control group.At the end of the treatment,the tumor volume in the gemcitabine alone group,the endostar first group,the gemcitabine first group,and the simultaneous group were obviously smaller,compared to the control group(P<0.05).Moreover,the tumor volume of the simultaneous group was the smallest compared with the all other groups(P<0.05).2.Metabolism of tumors in each group:The tumor metabolism of the gemcitabine alone group,the endostar first group,the gemcitabine first group,and the simultaneous group were lower than that of the control group(P<0.05).Additionaly,the tumor metabolism of the simultaneous group was the lowest in all treatment groups,and the SUVmax was significantly lower than all other treatment groups(P<0.05).3.Tumor hypoxia in each group:On the 5th and 10th day of the treatment,the oxygen partial pressure in the endostar alone group,the endostar first group,the gemcitabine first group and the simultaneous group all increased remarkablely,compared to the control group(P<0.05).Besides,on the 15th day of treatment,compared to the control group,the oxygen partial pressure level in endostar first group,the gemcitabine first group and the simultaneous group were still remarkablely higher(P<0.05),while no obvious difference was observed between the endostar alone and the control group on day 15 of treatment(P>0.05).4.Influence on the cell cycle distribution:Compared with the control group,the Endostar alone group had a higher proportion of cells in the G0/G1 phase(P<0.05).What's more,the cells fragment of the G0/G1 phase and S phase were observably higher compared to the control group(P<0.01).5.VEGF expression:The expression of VEGF in the endostar alone group,the endostar first group,the gemcitabine first group and the simultaneous group were significantly depleted compared with the control group(P<0.05).Meanwhile,the VEGF expression level in the simultaneous group was the lowest compared to all other treatment groups(P<0.05).6.Expression of ?-SMA:The expression of a-SMA in the simultaneous group was significantly higher compared to all other groups(P<0.05).Conclusion:1.Treatment of endostar combined with gemcitabine can effectively delay tumor growth,reduce tumor metabolism,and enhance anti-tumor effects.When treatment with endostar combined with gemcitabine simultaneously,the anti-tumor effect become more better.2.Endostar can improve the hypoxia in the tumor tissue.When endostar combined with gemcitabine,the tumor hypoxia is significantly improved.3.When Endostar combined with gemcitabine simultaneously,both the G0/G1 and S phase cells increased,resulted that the cell cycle distribution changed significantly.4.Endostar can down regulate the expression of VEGF,and the expression level of VEGF significantly decreased follow the treatment of endostar combined with gemcitabine simultaneously.5.Endostar combined with gemcitabine simultaneously increased a-SMA positive blood vessels expression and induced tumor vascular blood vessels to be mature,thereby improved vascular permeability and perfusion.Thus anti-tumor efficacy was enhanced under the treament of endostar combined with gemcitabine. |
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