Interactions between vitamin D and IGF-I: from physiology to clinical practice

Authors

  • Pietro Ameri,

    1. Division of Endocrinology, Department of Medicine, New York University School of Medicine, New York, NY, USA
    2. Unit of Internal Medicine, Department of Internal Medicine and Medical Specialties, IRCCS-AOU San Martino-IST, University of Genova, Genova, Italy
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  • Andrea Giusti,

    1. Department of Geriatrics and Musculoskeletal Sciences, E.O. Galliera Hospital, Genova, Italy
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  • Mara Boschetti,

    1. Unit of Endocrinology & Centre of Excellence for Biomedical Research, Department of Internal Medicine and Medical Specialties, IRCCS-AOU San Martino-IST, University of Genova, Genova, Italy
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  • Giovanni Murialdo,

    1. Unit of Internal Medicine, Department of Internal Medicine and Medical Specialties, IRCCS-AOU San Martino-IST, University of Genova, Genova, Italy
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  • Francesco Minuto,

    1. Unit of Endocrinology & Centre of Excellence for Biomedical Research, Department of Internal Medicine and Medical Specialties, IRCCS-AOU San Martino-IST, University of Genova, Genova, Italy
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  • Diego Ferone

    Corresponding author
    1. Unit of Endocrinology & Centre of Excellence for Biomedical Research, Department of Internal Medicine and Medical Specialties, IRCCS-AOU San Martino-IST, University of Genova, Genova, Italy
    • Division of Endocrinology, Department of Medicine, New York University School of Medicine, New York, NY, USA
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Correspondence: Diego Ferone, Endocrinology Unit (DiMI), University of Genova, Viale Benedetto XV, 6, Genova 16132, Italy. Tel.: +39 010 353 7946; Fax: +39 010 353 8977; E-mail: ferone@unige.it

Summary

The interplay between vitamin D and IGF-I is complex and occurs at both endocrine and paracrine/autocrine levels. Vitamin D has been shown to increase circulating IGF-I and IGFBP-3, with the consistent finding of a positive correlation between vitamin D and IGF-I serum values in population-based cohorts of healthy subjects. The modulation of IGF-I and IGFBP-3 concentrations by vitamin D may impact recombinant human (rh) GH dosing for the treatment of GHD. It might also underlie some of the extra-skeletal beneficial effects ascribed to vitamin D. On the other hand, IGF-I stimulates renal production of 1,25-dihydroxyvitamin D, which increases calcium and phosphate availability in the body and suppresses PTH secretion. This effect is responsible for an altered calcium–phosphate balance in uncontrolled acromegaly and might also account for the improvement in bone metabolism associated with rhGH treatment in patients with GHD. Data on the paracrine/autocrine vitamin D−IGF-I interactions are abundant, but mostly not linked to one another. As a result, it is not possible to draw a comprehensive picture of the physiological and/or pathological interrelations between vitamin D, IGF-I and IGF-binding proteins (IGFBP) in different tissues. A potential role of vitamin D action is related to its association with carcinogenesis, a paradigm being breast cancer. Current evidence indicates that, in breast tumours, vitamin D modulates the IGF-I/IGFBP ratio to decrease proliferation and increase apoptosis.

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