title: Anti-tumor effect of a novel soluble recombinant human endostatin: administered as a single agent or in combination with chemotherapy agents in mouse tumor models.
abstract: BACKGROUND
  Angiogenesis has become an attractive target in cancer treatment. Endostatin is one of the potent anti-angiogenesis agents. Its recombinant form expressed in the yeast system is currently under clinical trials. Endostatin suppresses tumor formation through the inhibition of blood vessel growth. It is anticipated that combined therapy using endostatin and cytotoxic compounds may exert an additive effect. In the present study, we expressed and purified recombinant human endostatin (rhEndostatin) that contained 3 additional amino acid residues (arginine, glycine, and serine) at the amino-terminus and 6 histidine residues in its carboxyl terminus. The recombinant protein was expressed in E. Coli and refolded into a soluble form in a large scale purification process. The protein exhibited a potent anti-tumor activity in bioassays. Furthermore, rhEndostatin showed an additive effect with chemotherapy agents including cyclophosphamide (CTX) and cisplatin (DDP).
  
  
  METHODS
  rhEndostatin cDNA was cloned into PQE vector and expressed in E. Coli. The protein was refolded through dialysis with an optimized protocol. To establish tumor models, nude mice were subcutaneously injected with human cancer cells (lung carcinoma A549, hepatocellular carcinoma QGY-7703, or breast cancer Bcap37). rhEndostatin and/or DDP was administered peritumorally to evaluate the rate of growth inhibition of A549 tumors. For the tumor metastasis model, mice were injected intravenously with mouse melanoma B16 cells. One day after tumor cell injection, a single dose of rhEndostatin, or in combination with CTX, was administered intravenously or at a site close to the tumor.
  
  
  RESULTS
  rhEndostatin reduced the growth of A549, QGY-7703, and Bcap37 xenograft tumors in a dose dependent manner. When it was administered peritumorally, rhEndostatin exhibited a more potent inhibitory activity. Furthermore, rhEndostatin displayed an additive effect with CTX or DDP on the inhibition of metastasis of B16 tumors or growth of A549 tumors.
  
  
  CONCLUSIONS
  Soluble rhEndostatin exhibits a potent anti-tumor activity in mouse xenograft models and it also has an additive effect with CTX and DDP, implying possible applications in clinical settings.
authors.affiliation: Biopharmagen Corp., Suzhou, China; Biopharmaceutical R&D Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China.
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Ren
authors.affiliation: Department of Laboratory Diagnosis, Suzhou Municipal Hospital Affiliated Nanjing Medical University, Suzhou, China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Biopharmagen Corp., Suzhou, China.
authors.forename: Wenhong
authors.initials: W
authors.lastname: Jiang
authors.affiliation: Biopharmaceutical R&D Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China; Department of Environmental Medicine, New York University Langone Medical Center, Tuxedo, New York, United States of America.
authors.forename: Wei
authors.initials: W
authors.lastname: Dai
authors.affiliation: Biopharmagen Corp., Suzhou, China; Biopharmaceutical R&D Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D020533:Angiogenesis Inhibitors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002945:Cisplatin / Q000008:administration & dosage / Q000494:pharmacology; D004195:Disease Models, Animal; D043169:Endostatins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D000091402:Prohibitins; D058849:Protein Refolding; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D012995:Solubility; D023041:Xenograft Model Antitumor Assays
chemical_list: D020533:Angiogenesis Inhibitors; D000970:Antineoplastic Agents; D043169:Endostatins; C000717331:PHB2 protein, human; C000717333:Phb2 protein, mouse; D000091402:Prohibitins; D011994:Recombinant Proteins; D002945:Cisplatin