Real-Time PCR Study of Ang1, Ang2, Tie-2, VEGF, and KDR Expression in Human Erectile Tissue during Aging

Authors

  • António Figueiredo MD,

    Corresponding author
    1. Faculty of Medicine of Universidade do Porto—Laboratory for Molecular Cell Biology—Porto, Portugal
    2. Universidade do Porto—IBMC, Porto, Portugal
      António Figueiredo, MD, Laboratory for Molecular Cell Biology, Faculty of Medicine of Universidade do Porto, Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. Tel: 351225513654; Fax: 351225513655; E-mail: antonio.f.figueiredo@gmail.com
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  • Ana Lúcia Cordeiro MD,

    1. Faculty of Medicine of Universidade do Porto—Laboratory for Molecular Cell Biology—Porto, Portugal
    2. Universidade do Porto—IBMC, Porto, Portugal
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  • Nuno Tomada MD,

    1. Faculty of Medicine of Universidade do Porto—Laboratory for Molecular Cell Biology—Porto, Portugal
    2. Universidade do Porto—IBMC, Porto, Portugal
    3. Hospital de S. João—Department of Urology, Porto, Portugal
    4. Faculty of Medicine of Universidade do Porto—Department of Urology, Porto, Portugal
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  • Inês Tomada MSc,

    1. Faculty of Medicine of Universidade do Porto—Laboratory for Molecular Cell Biology—Porto, Portugal
    2. Universidade do Porto—IBMC, Porto, Portugal
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  • Adriana Rodrigues PhD student,

    1. Faculty of Medicine of Universidade do Porto—Laboratory for Molecular Cell Biology—Porto, Portugal
    2. Universidade do Porto—IBMC, Porto, Portugal
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  • Alexandra Gouveia PhD,

    1. Faculty of Medicine of Universidade do Porto—Laboratory for Molecular Cell Biology—Porto, Portugal
    2. Universidade do Porto—IBMC, Porto, Portugal
    3. Universidade do Porto—Faculty of Nutrition and Food Sciences, Porto, Portugal
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  • Delminda Neves PhD

    1. Faculty of Medicine of Universidade do Porto—Laboratory for Molecular Cell Biology—Porto, Portugal
    2. Universidade do Porto—IBMC, Porto, Portugal
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António Figueiredo, MD, Laboratory for Molecular Cell Biology, Faculty of Medicine of Universidade do Porto, Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. Tel: 351225513654; Fax: 351225513655; E-mail: antonio.f.figueiredo@gmail.com

ABSTRACT

Introduction.  Aging is a recognized risk factor for erectile dysfunction (ED), contributing independently to vascular damage of penile tissue. Vascular maintenance depends on angiogenic balance in tissues. Vascular endothelial growth factor (VEGF) is a modulator of endothelial cells functions, after engagement to specific receptor kinase domain region (KDR). Other factors, such as angiopoietins, cross talk with VEGF, modulating its effects. Angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2) compete for binding to Tie-2 and, while Ang1 promotes vascular stabilization, Ang2 acts as a partial agonist or antagonist of Ang1 signaling, depending on VEGF bioavailability.

Aims.  To quantify the expression of Ang1, Ang2, Tie-2, VEGF, and KDR by real-time polymerase chain reaction (PCR) in human corpus cavernosum (CC) from young and aged healthy individuals.

Methods.  Human CC fragments were obtained from organ donors without known risk factors to ED and divided in two groups: young (16–35 years) and aged (59–74 years). RNA was extracted and converted to cDNA. Real-time PCR reactions employed appropriate primers. KDR, Tie-2, Akt, and phospho-Akt protein levels were also assessed by Western blotting (WB). Computer-assisted evaluation of vascular areas was performed.

Main Outcome Measures.  Study of angiopoietins-Tie-2 and VEGF-KDR systems in human CC during aging by real-time PCR and WB. The ratios Ang1/Tie-2 and VEGF/KDR and Akt levels were also determined.

Results.  Real-time PCR results showed a sixfold significant reduction in the Ang1/Tie-2 ratio during aging. Ang2, VEGF, and KDR expression results were highly variable. Nevertheless, the ratio VEGF/KDR was significantly higher in the aged individuals. Akt and phospho-Akt levels were similar in both groups. Immunohistological evaluation revealed a significant decrease in vascular areas and endothelial surface in CC with aging, despite no differences found in vessel number.

Conclusions.  The obtained results suggest an aging-associated downregulation of angiopoietins/Tie-2 system and an apparent compensatory upregulation of the VEGF/KDR system. Figueiredo A, Cordeiro AL, Tomada N, Tomada I, Rodrigues A, Gouveia A, and Neves D. Real-time PCR study of Ang1, Ang2, Tie-2, VEGF, and KDR expression in human erectile tissue during aging. J Sex Med 2011;8:1341–1351.

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