Bladder cancer cell growth and motility implicate cannabinoid 2 receptor-mediated modifications of sphingolipids metabolism

Sci Rep. 2017 Feb 13:7:42157. doi: 10.1038/srep42157.

Abstract

The inhibitory effects demonstrated by activation of cannabinoid receptors (CB) on cancer proliferation and migration may also play critical roles in controlling bladder cancer (BC). CB expression on human normal and BC specimens was tested by immunohistochemistry. Human BC cells RT4 and RT112 were challenged with CB agonists and assessed for proliferation, apoptosis, and motility. Cellular sphingolipids (SL) constitution and metabolism were evaluated after metabolic labelling. CB1-2 were detected in BC specimens, but only CB2 was more expressed in the tumour. Both cell lines expressed similar CB2. Exposure to CB2 agonists inhibited BC growth, down-modulated Akt, induced caspase 3-activation and modified SL metabolism. Baseline SL analysis in cell lines showed differences linked to unique migratory behaviours and cytoskeletal re-arrangements. CB2 activation changed the SL composition of more aggressive RT112 cells by reducing (p < 0.01) Gb3 ganglioside (-50 ± 3%) and sphingosine 1-phosphate (S1P, -40 ± 4%), which ended up to reduction in cell motility (-46 ± 5%) with inhibition of p-SRC. CB2-selective antagonists, gene silencing and an inhibitor of SL biosynthesis partially prevented CB2 agonist-induced effects on cell viability and motility. CB2 activation led to ceramide-mediated BC cell apoptosis independently of SL constitutive composition, which instead was modulated by CB2 agonists to reduce cell motility.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Biological Assay
  • Cannabinoid Receptor Agonists / pharmacology
  • Cannabinoid Receptor Antagonists / pharmacology
  • Carcinoma, Transitional Cell / genetics
  • Carcinoma, Transitional Cell / metabolism*
  • Carcinoma, Transitional Cell / pathology
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Cell Line
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Fibroblasts / cytology
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Immunohistochemistry
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptor, Cannabinoid, CB1 / genetics*
  • Receptor, Cannabinoid, CB1 / metabolism
  • Receptor, Cannabinoid, CB2 / genetics*
  • Receptor, Cannabinoid, CB2 / metabolism
  • Signal Transduction
  • Sphingolipids / metabolism*
  • Urinary Bladder Neoplasms / genetics
  • Urinary Bladder Neoplasms / metabolism*
  • Urinary Bladder Neoplasms / pathology
  • Wound Healing / drug effects
  • src-Family Kinases / genetics
  • src-Family Kinases / metabolism

Substances

  • CNR2 protein, human
  • Cannabinoid Receptor Agonists
  • Cannabinoid Receptor Antagonists
  • Receptor, Cannabinoid, CB1
  • Receptor, Cannabinoid, CB2
  • Sphingolipids
  • src-Family Kinases
  • Proto-Oncogene Proteins c-akt
  • CASP3 protein, human
  • Caspase 3