Renal uptake of different radiolabelled peptides is mediated by megalin: SPECT and biodistribution studies in megalin-deficient mice

Erik Vegt*, Marleen Melis, Annemarie Eek, Monique de Visser, Maarten Brom, Wim J. G. Oyen, Martin Gotthardt, Marion de Jong, Otto C. Boerman

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

81 Citations (Web of Science)

Abstract

Radiolabelled peptides used for peptide receptor radionuclide therapy are excreted mainly via the kidneys and are partly reabsorbed and retained in the proximal tubular cells. The resulting high renal radiation dose can cause nephrotoxicity, limiting the maximum activity dose and the effectiveness of peptide receptor radionuclide therapy. The mechanisms of kidney reabsorption of these peptides are incompletely understood, but the scavenger receptor megalin has been shown to play a role in the reabsorption of In-111-octreotide. In this study, the role of megalin in the renal reabsorption of various relevant radiolabelled peptides was investigated. Groups of kidney-specific megalin-deficient mice and wild-type mice were injected with In-111-labelled somatostatin, exendin, neurotensin or minigastrin analogues. Single photon emission computed tomographic (SPECT) images of the kidneys were acquired and analysed quantitatively, or the animals were killed 3 h after injection and the activity concentration in the kidneys was measured. Megalin-deficient mice showed significantly lower uptake of all studied radiolabelled peptides in the kidneys, ranging from 22% (In-111-octreotide) to 65% (In-111-exendin) of uptake in wild-type kidneys. Quantitative analysis of renal uptake by SPECT and ex vivo measurements showed a very good correlation. Megalin is involved in the renal reabsorption of radiolabelled octreotide, octreotate, exendin, neurotensin and minigastrin. This knowledge may help in the design of strategies to reduce this reabsorption and the resulting nephrotoxicity in peptide receptor radionuclide therapy, enabling more effective therapy. Small-animal SPECT is an accurate tool, allowing in vivo quantification of renal uptake and serial measurements in individual mice.
Original languageEnglish
Pages (from-to)623-632
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Volume38
Issue number4
DOIs
Publication statusPublished - Apr 2011

Keywords

  • Kidney
  • Megalin
  • Peptide receptor radionuclide therapy
  • Octreotide
  • Octreotate
  • Exendin
  • Neurotensin
  • Minigastrin

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