Inhibitory effect of Bifidobacterium infantis-mediated sKDR prokaryotic expression system on angiogenesis and growth of Lewis lung cancer in mice.

BACKGROUND: To construct the Bifidobacterium infantis-mediated soluble kinase insert domain receptor (sKDR) prokaryotic expression system and to observe its inhibitory effect on growth of human umbilicus vessel endothelial cells (HUVECs) in vitro and Lewis lung cancer (LLC) on mice in vivo. METHODS: The Bifidobacterium infantis-mediated sKDR prokaryotic expression system was constructed through electroporation and subsequently identified through PCR and Western blot analysis. HUVECs were added to the products of this system to evaluate the anti-angiogenesis effect through MTT assay in vitro. The LLC mice models were divided into three groups: one group treated with saline (group a); one group treated with recombinant Bifidobacterium infantis containing pTRKH2-PsT plasmid group (group b); and one group treated with recombinant Bifidobacterium infantis containing pTRKH2-PsT/sKDR plasmid group (group c). The quality of life and survival of mice were recorded. Tumor volume, tumor weight, inhibitive rate, and necrosis rate of tumor were also evaluated. Necrosis of tumor and signals of blood flow in tumors were detected through color Doppler ultrasound. In addition, microvessel density (MVD) of the tumor tissues was assessed through CD31 immunohistochemical analysis. RESULTS: The positively transformed Bifidobacterium infantis with recombinant pTRKH2-PsT/sKDR plasmid was established, and was able to express sKDR at gene and protein levels. The proliferation of HUVECs cultivated with the extract of positively transformed bacteria was inhibited significantly compared with other groups (P < 0. 05). The quality of life of mice in group c was better than in group a and b. The recombinant Bifidobacterium infantis containing pTRKH2-PsT/sKDR plasmid enhanced the efficacy of tumor growth suppression and prolongation of survival, increased the necrosis rate of tumor significantly, and could obviously decrease MVD and the signals of blood flow in tumors. CONCLUSION: The Bifidobacterium infantis-mediated sKDR prokaryotic expression system was constructed successfully. This system could express sKDR at gene and protein levels and significantly inhibit the growth of HUVECs induced by VEGF in vitro. Moreover, it could inhibit tumor growth and safely prolong the survival time of LLC C57BL/6 mice.

Inhibitory effect of ginsenoside Rg3 combined with gemcitabine on angiogenesis and growth of lung cancer in mice.

BACKGROUND: Ginsenoside Rg3, a saponin extracted from ginseng, inhibits angiogenesis. The combination of low-dose chemotherapy and anti-angiogenic inhibitors suppresses growth of experimental tumors more effectively than conventional therapy or anti-angiogenic agent alone. The present study was designed to evaluate the efficacy of low-dose gemcitabine combined with ginsenoside Rg3 on angiogenesis and growth of established Lewis lung carcinoma in mice. METHODS: C57L/6 mice implanted with Lewis lung carcinoma were randomized into the control, ginsenoside Rg3, gemcitabine and combination group. The quality of life and survival of mice were recorded. Tumor volume, inhibitive rate and necrosis rate were estimated. Necrosis of tumor and signals of blood flow as well as dynamic parameters of arterial blood flow in tumors such as peak systolic velocity (PSV) and resistive index (RI) were detected by color Doppler ultrasound. In addition, expression of vascular endothelial cell growth factor (VEGF) and CD31 were observed by immunohistochemstry, and microvessel density (MVD) of the tumor tissues was assessed by CD31 immunohistochemical analysis. RESULTS: Quality of life of mice in the ginsenoside Rg3 and combination group were better than in the control and gemcitabine group. Combined therapy with ginsenoside Rg3 and gemcitabine not only enhanced efficacy on suppression of tumor growth and prolongation of the survival, but also increased necrosis rate of tumor significantly. In addition, the combination treatment could obviously decrease VEGF expression and MVD as well as signals of blood flow and PSV in tumors. CONCLUSION: Ginsenoside Rg3 combined with gemcitabine may significantly inhibit angiogenesis and growth of lung cancer and improve survival and quality of life of tumor-bearing mice. The combination of chemotherapy and anti-angiogenic drugs may be an innovative and promising therapeutic strategy in the experimental treatment of human lung cancer.

[Cloning and prokaryotic expression of Bifidobacterium infantis-mediated sKDR and its effect on proliferation of vascular endothelial cells].

OBJECTIVE: To construct Bifidobacterium Infantis-mediated sKDR gene transferring system and to investigate its effect on the proliferation of vascular endothelial cells. METHODS: sKDR gene amplified through PCR, and pET32a plasmid extracted from E. coli JM109 were digested respectively by two kinds of restriction enzyme (EcoR I and Xho I) and then were connected by T4 DNA Ligase. Finally, the recombinant plasmid was transformed into Bifidobacterium Infantis by electroporation. Human umbilicus vein endothelial cells (HUVECs) were cultivated in the nutritive media containing the extract of positive transformed bacteria for 24 h. The cell viability was analyzed with MTT assay. RESULTS: The positive transformed Bifidobacterium Infantis with recombinant pET32a-sKDR plasmid was established and could express sKDR at the levels of gene and protein. Compared with the untreated group, the proliferation of HUVECs cultivated with the extract of positive transformed bacteria was inhibited significantly (P<0.01). CONCLUSION: The Bifidobacterium Infantis-mediated sKDR gene transferring system was constructed successfully and it could remarkably inhibit the proliferation of vascular endothelial cells.