title: Inhibitory effect of Bifidobacterium infantis-mediated sKDR prokaryotic expression system on angiogenesis and growth of Lewis lung cancer in mice.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Abdominal Cancer, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China.
authors.forename: Zhao-Jun
authors.initials: ZJ
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Zhu
authors.forename: Bu-Yun
authors.initials: BY
authors.lastname: Ma
authors.forename: Fen
authors.initials: F
authors.lastname: Zhao
authors.forename: Shu-Hua
authors.initials: SH
authors.lastname: Mao
authors.forename: Tai-Guo
authors.initials: TG
authors.lastname: Liu
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: He
authors.forename: Li-Cong
authors.initials: LC
authors.lastname: Deng
authors.forename: Cheng
authors.initials: C
authors.lastname: Yi
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000818:Animals; D001644:Bifidobacterium / Q000235:genetics*; D018827:Carcinoma, Lewis Lung / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D015870:Gene Expression; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000235:genetics* / Q000378:metabolism; D047368:Tumor Burden; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics* / Q000378:metabolism
chemical_list: D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2