Structural characterisation of high affinity Siglec-2 (CD22) ligands in complex with whole Burkitt's lymphoma (BL) Daudi cells by NMR spectroscopy

Sci Rep. 2016 Nov 3;6:36012. doi: 10.1038/srep36012.

Abstract

Siglec-2 undergoes constitutive endocytosis and is a drug target for autoimmune diseases and B cell-derived malignancies, including hairy cell leukaemia, marginal zone lymphoma, chronic lymphocytic leukaemia and non-Hodgkin's lymphoma (NHL). An alternative to current antibody-based therapies is the use of liposomal nanoparticles loaded with cytotoxic drugs and decorated with Siglec-2 ligands. We have recently designed the first Siglec-2 ligands (9-biphenylcarboxamido-4-meta-nitrophenyl-carboxamido-Neu5Acα2Me, 9-BPC-4-mNPC-Neu5Acα2Me) with simultaneous modifications at C-4 and C-9 position. In the current study we have used Saturation Transfer Difference (STD) NMR spectroscopy to monitor the binding of 9-BPC-4-mNPC-Neu5Acα2Me to Siglec-2 present on intact Burkitt's lymphoma Daudi cells. Pre-treatment of cells with periodate resulted in significantly higher STD NMR signal intensities for 9-BPC-4-mNPC-Neu5Acα2Me as the cells were more susceptible to ligand binding because cis-binding on the cell surface was removed. Quantification of STD NMR effects led to a cell-derived binding epitope of 9-BPC-4-mNPC-Neu5Acα2Me that facilitated the design and synthesis of C-2, C-3, C-4 and C-9 tetra-substituted Siglec-2 ligands showing an 88-fold higher affinity compared to 9-BPC-Neu5Acα2Me. This is the first time a NMR-based binding study of high affinity Siglec-2 (CD22) ligands in complex with whole Burkitt's lymphoma Daudi cells has been described that might open new avenues in developing tailored therapeutics and personalised medicine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Burkitt Lymphoma / metabolism*
  • Burkitt Lymphoma / pathology*
  • Cell Line, Tumor
  • Epitopes / metabolism
  • Flow Cytometry
  • HEK293 Cells
  • Humans
  • Ligands
  • Magnetic Resonance Spectroscopy*
  • N-Acetylneuraminic Acid / chemistry
  • N-Acetylneuraminic Acid / metabolism
  • Periodic Acid / metabolism
  • Recombinant Proteins / metabolism
  • Sialic Acid Binding Ig-like Lectin 2 / chemistry*
  • Sialic Acid Binding Ig-like Lectin 2 / metabolism*
  • Surface Plasmon Resonance
  • Transfection

Substances

  • Epitopes
  • Ligands
  • Recombinant Proteins
  • Sialic Acid Binding Ig-like Lectin 2
  • Periodic Acid
  • metaperiodate
  • N-Acetylneuraminic Acid