Metabolic characteristics of 13-cis-retinoic acid (isotretinoin) and anti-tumour activity of the 13-cis-retinoic acid metabolite 4-oxo-13-cis-retinoic acid in neuroblastoma.

Isotretinoin (13-cis-retinoic acid; 13-cRA) is a differentiation inducer used to treat minimal residual disease after myeloablative therapy for high-risk neuroblastoma. However, more than 40% of children develop recurrent disease during or after 13-cRA treatment. The plasma concentrations of 13-cRA in earlier studies were considered subtherapeutic while 4-oxo-13-cis-RA (4-oxo-13-cRA), a metabolite of 13-cRA considered by some investigators as inactive, were greater than threefold higher than 13-cRA. We sought to define the metabolic pathways of 13-cRA and investigated the anti-tumour activity of its major metabolite, 4-oxo-13-cRA.
Effects of 13-cRA and 4-oxo-13-cRA on human neuroblastoma cell lines were assessed by DIMSCAN and flow cytometry for cell proliferation, MYCN down-regulation by reverse transcription PCR and immunoblotting, and neurite outgrowth by confocal microscopy. 13-cRA metabolism was determined using tandem MS in human liver microsomes and in patient samples.
Six major metabolites of 13-cRA were identified in patient samples. Of these, 4-oxo-13-cRA was the most abundant, and 4-oxo-13-cRA glucuronide was also detected at a higher level in patients. CYP3A4 was shown to play a major role in catalysing 13-cRA to 4-oxo-13-cRA. In human neuroblastoma cell lines, 4-oxo-13-cRA and 13-cRA were equi-effective at inducing neurite outgrowth, inhibiting proliferation, decreasing MYCN mRNA and protein, and increasing the expression of retinoic acid receptormRNA and protein levels.
We showed that 4-oxo-13-cRA is as active as 13-cRA against neuroblastoma cell lines. Plasma levels of both 13-cRA and 4-oxo-13-cRA should be evaluated in pharmacokinetic studies of isotretinoin in neuroblastoma.
AuthorsPoonam Sonawane, Hwang Eui Cho, Ashujit Tagde, Dattesh Verlekar, Alice L Yu, C Patrick Reynolds, Min H Kang
JournalBritish journal of pharmacology (Br J Pharmacol) Vol. 171 Issue 23 Pg. 5330-44 (Dec 2014) ISSN: 1476-5381 [Electronic] England
PMID25039756 (Publication Type: Clinical Trial, Phase III, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
Copyright© 2014 The British Pharmacological Society.
Chemical References
  • Antineoplastic Agents
  • MYCN protein, human
  • Nuclear Proteins
  • Oncogene Proteins
  • RNA, Messenger
  • Receptors, Retinoic Acid
  • retinoic acid receptor beta
  • 4-oxoretinoic acid
  • Tretinoin
  • CYP3A4 protein, human
  • CYP3A5 protein, human
  • Cytochrome P-450 CYP3A
  • Isotretinoin
  • Animals
  • Antineoplastic Agents (blood, pharmacokinetics, pharmacology)
  • Cell Line, Tumor
  • Cell Proliferation (drug effects)
  • Central Nervous System Neoplasms (blood, drug therapy, metabolism)
  • Chromatography, High Pressure Liquid
  • Cytochrome P-450 CYP3A (metabolism)
  • Humans
  • Isotretinoin (blood, pharmacokinetics, pharmacology)
  • Mice, Inbred BALB C
  • Microsomes (drug effects, metabolism)
  • Neurites (drug effects)
  • Neuroblastoma (blood, drug therapy, metabolism)
  • Nuclear Proteins (genetics, metabolism)
  • Oncogene Proteins (genetics, metabolism)
  • RNA, Messenger (metabolism)
  • Receptors, Retinoic Acid (genetics, metabolism)
  • Tandem Mass Spectrometry
  • Tretinoin (analogs & derivatives, blood, pharmacology)

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