Antagonists of bombesin/gastrin-releasing peptide decrease the expression of angiogenic and anti-apoptotic factors in human glioblastoma

Celia A. Kanashiro, Andrew V. Schally, R. Z. Cai, Gabor Halmos

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

We have investigated the antitumor effects and the mechanism of action of antagonists of bombesin/gastrin-releasing peptide (GRP), RC-3940-II and RC-3940-Et, on the growth of U-118MG human malignant glioma xenografted into nude mice. Tumors volume was measured weekly, and after 6 weeks of treatment with GRP antagonists the tumors were analyzed by Western blot assays for the expression of vascular endothelial growth factor (VEGF), protein kinase C (PKC)-α, the anti-apoptotic protein Bcl-2 and the pro-apoptotic protein Bax. A radioreceptor assay was used to characterize the receptors for bombesin/GRP. Specific high-affinity receptors for bombesin were found in U-118MG tumors, and their growth was reduced by 52.5% by RC-3940-II and 72.6% by RC-3940-Et (both p < 0.01). The tumor doubling time was prolonged by 4.6 and 12 days after treatment with RC-3940-II and RC-3940-Et, respectively, compared to controls (p < 0.05). Both antagonists caused a significant (p < 0.05) decrease of about 28% in the levels of VEGF protein and a reduction of approximately 35% in the expression of PKCα. The relative ratio of Bcl-2:Bax was also diminished by around 70% by both analogs, indicating a net apoptotic gain and the efficacy of treatment. Our results suggest that bombesin/GRP antagonists, RC-3940-II and RC-3940-Et, could be of value for the treatment of human glioblastomas.

Original languageEnglish (US)
Pages (from-to)159-165
Number of pages7
JournalAnti-Cancer Drugs
Volume16
Issue number2
DOIs
StatePublished - Feb 1 2005

    Fingerprint

Keywords

  • Antagonist
  • Bax
  • Bcl-2
  • Bombesin
  • Brain tumor
  • Gastrin-releasing peptide
  • Protein kinase C
  • Vascular endothelial growth factor

ASJC Scopus subject areas

  • Pharmacology
  • Cancer Research
  • Oncology

Cite this