Hematopoietic cells expressing the peripheral cannabinoid receptor migrate in response to the endocannabinoid 2-arachidonoylglycerol

Blood. 2002 Apr 15;99(8):2786-93. doi: 10.1182/blood.v99.8.2786.

Abstract

Cb2 is a novel protooncogene encoding the peripheral cannabinoid receptor. Previous studies demonstrated that 2 distinct noncoding first exons exist: exon-1A and exon-1B, which both splice to protein-coding exon-2. We demonstrate that in retrovirally induced murine myeloid leukemia cells with proviral insertion in Cb2, exon-1B/exon-2 Cb2 messenger RNA levels have been increased, resulting in high receptor numbers. In myeloid leukemia cells without virus insertion in this locus, low levels of only exon-1A/exon-2 Cb2 transcripts were present and receptors could not be detected. To elucidate the function of Cb2 in myeloid leukemia cells, a set of in vitro experiments was carried out using 32D/G-CSF-R (granulocyte colony-stimulating factor receptor) cells transfected with exon-1B/exon-2 Cb2 complementary DNA and a myeloid cell line carrying a virus insertion in Cb2 (ie, NFS 78). We demonstrate that a major function of the Cb2 receptor is stimulation of migration as determined in a transwell assay. Exposure of Cb2-expressing cells to different cannabinoids showed that the true ligand for Cb2 is 2-arachidonoylglycerol (2-AG), which may act as chemoattractant and as a chemokinetic agent. Furthermore, we observed a significant synergistic activity between 2-AG and interleukin-3 or G-CSF, suggesting cross-talk between the different receptor systems. Radioactive-ligand binding studies revealed significant numbers of Cb2 receptors in normal spleen. Transwell experiments carried out with normal mouse spleen cells showed 2-AG-induced migration of B220-, CD19-, immunoglobulin M-, and immunoglobulin D-expressing B lymphocytes. Our study demonstrates that a major function of Cb2 receptor expressed on myeloid leukemia cells or normal splenocytes is stimulation of migration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachidonic Acids*
  • B-Lymphocytes / drug effects
  • B-Lymphocytes / metabolism
  • Cannabinoid Receptor Modulators
  • Cannabinoids / pharmacology
  • Chemotaxis / drug effects*
  • Cytokines / pharmacology
  • Drug Interactions
  • Endocannabinoids
  • Glycerides / pharmacology*
  • Leukemia, Myeloid / pathology
  • Ligands
  • Mice
  • Myeloid Cells / chemistry
  • Myeloid Cells / drug effects*
  • Receptors, Cannabinoid
  • Receptors, Drug / genetics
  • Receptors, Drug / physiology*
  • Spleen / cytology
  • Thymus Gland / cytology
  • Transfection
  • Tumor Cells, Cultured

Substances

  • Arachidonic Acids
  • Cannabinoid Receptor Modulators
  • Cannabinoids
  • Cytokines
  • Endocannabinoids
  • Glycerides
  • Ligands
  • Receptors, Cannabinoid
  • Receptors, Drug
  • glyceryl 2-arachidonate