title: Effects of MDM2 inhibitors on vascular endothelial growth factor-mediated tumor angiogenesis in human breast cancer.
abstract: BACKGROUND
  Mouse double minute 2 (MDM2) is overexpressed in many malignant tumors, and MDM2 levels are associated with poor prognosis of several human cancers, including breast cancer. In the present study, we investigated the function of MDM2 in vascular endothelial growth factor (VEGF)-mediated tumor angiogenesis of breast cancer and the potential value of MDM2 as an anti-angiogenic therapy target for cancer therapy by inhibiting MDM2 with antisense oligonucleotides (ASO) or other antagonist nutlin-3.
  
  
  METHODS
  Anti-MDM2 ASO and nutlin-3 were evaluated for their in vitro and in vivo anti-angiogenesis activities in different human breast cancer models with a different p53 status: MCF-7 cell line containing wild-type p53 and MDA-MB-468 cell line containing mutant p53. MCF-7 and MDA-MB-468 cells were incubated with different concentrations of ASO or nutlin-3 for various periods of time. VEGF gene and protein expression in tumor cells was measured by qPCR and Western blot. The level of VEGF protein secreted in the culture supernatant of treated cells was quantified by enzyme-linked immunosorbent assay (ELISA). Nude mouse xenograft models were further established to determine their effects on tumor growth and angiogenesis. Serum levels of VEGF were measured by ELISA. VEGF expression and microvessel density in tumor tissues were studied by immunohistochemistry. Both angiogenesis and tumor growth were digitally quantified.
  
  
  RESULTS
  In both MCF-7 and MDA-MB-468 cells, VEGF expression and secretion were reduced, resulting from specific inhibition of MDM2 expression by ASO. In vivo assay, after administration of ASO, VEGF production reduced and anti-angiogenesis activity occurred in nude mice bearing MCF-7 or MDA-MB-468 xenograft. However, in both models treated with nutlin-3, VEGF production was not changed and anti-angiogenesis activity was not observed.
  
  
  CONCLUSIONS
  In summary, the ASO construct targeting MDM2 specifically suppresses VEGF expression in vitro and VEGF-mediated tumor angiogenesis in vivo in breast cancer. Furthermore, the suppression of VEGF expression subsequent to inhibition of MDM2 in p53 mutant cells suggests that MDM2 has a regulatory role on VEGF expression through a p53-independent mechanism.
authors.affiliation: Institute of Pathology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xiong
authors.forename: Qin
authors.initials: Q
authors.lastname: Yang
authors.forename: Jiansha
authors.initials: J
authors.lastname: Li
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhou
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000098:blood supply / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D064593:Heterografts; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D007093:Imidazoles; D016376:Oligonucleotides, Antisense; D010879:Piperazines; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C482205:nutlin 3; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2