Angiotensin-(1-7) reduces proliferation and angiogenesis of human prostate cancer xenografts with a decrease in angiogenic factors and an increase in sFlt-1

Authors

  • Bhavani Krishnan,

    1. Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
    2. Molecular Genetics and Genomics Program, Wake Forest University School of Medicine, Winston-Salem, North Carolina
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  • Frank M. Torti,

    1. Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, North Carolina
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  • Patricia E. Gallagher,

    1. Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
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  • E. Ann Tallant

    Corresponding author
    1. Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
    2. Molecular Genetics and Genomics Program, Wake Forest University School of Medicine, Winston-Salem, North Carolina
    • Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Medical Center Boulevard, Winston Salem, NC 27157.
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  • Conflicts of interest: EA Tallant and PE Gallagher hold a patent for the treatment of cancer with Ang-(1-7). The other authors disclosed no potential conflict of interest.

Abstract

BACKGROUND

Prostate cancer is the most frequently diagnosed malignancy and the second-leading cause of cancer death in men. The purpose of this study was to determine the anti-proliferative and anti-angiogenic efficacy of angiotensin-(1-7) [Ang-(1-7)], an endogenous peptide hormone, in human prostate cancer xenografts.

METHODS

Human LNCaP prostate cancer cells were injected into the flank of athymic mice and tumors were treated with Ang-(1-7) for 54 days. Tumor growth and angiogenesis were determined by immunohistochemistry and western blot hybridization.

RESULTS

Ang-(1-7) markedly reduced the volume and wet weight of LNCaP xenograft tumors. Histological analysis of tumor sections from saline-treated mice showed increased Ki67 immunoreactivity and enhanced phosphorylation of the MAP kinases ERK1/2 compared to tumors from Ang-(1-7)-treated mice, suggesting that the heptapeptide reduces cell proliferation. Intratumoral vessel density was decreased in Ang-(1-7)-treated mice with an associated reduction in vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), suggesting that the heptapeptide attenuates vascularization by reducing angiogenic factors. Ang-(1-7) administration markedly increased the soluble fraction of VEGF receptor 1 (sFlt-1), with a concomitant reduction in VEGF receptors 1 and 2. sFlt-1 serves as a decoy receptor that traps VEGF and PlGF, making the ligands unavailable to membrane-bound VEGF receptors and preventing activation of pro-angiogenic signaling.

CONCLUSIONS

The decrease in PlGF and VEGF coupled with the increase in sFlt-1 suggests that Ang-(1-7) may serve as a novel anti-angiogenic therapy for prostate cancer. Further, the pleiotropic mechanisms of action by Ang-(1-7) may limit angiogenic resistance that occurs with VEGF inhibitors or receptor blockers. Prostate 73: 60–70, 2013. © 2012 Wiley Periodicals, Inc.

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