Kathryn E Burns1, Daniel Allright2, David Porter3, Michael P Findlay3,4, Nuala A Helsby2. 1. Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. k.burns@auckland.ac.nz. 2. Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. 3. Auckland Regional Cancer and Blood Service, Auckland City Hospital, Private Bag 92024, Auckland, 1142, New Zealand. 4. Cancer Trials New Zealand, University of Auckland, Auckland, New Zealand.
Abstract
PURPOSE: Fluorouracil (5-FU), a chemotherapeutic agent widely used in the treatment of numerous common malignancies, causes oral mucositis in a proportion of patients. The contribution of drug transport processes to the development of this toxicity is currently unknown. This work aimed to establish and optimise a simple phenotyping assay for 5-FU uptake into primary buccal mucosal cells (BMC). METHODS: The uptake kinetics of radiolabelled 5-FU were determined in pooled BMC freshly collected from healthy volunteers. The inter- and intra-individual variability in 5-FU uptake was then assessed across a cohort that included both healthy volunteers and cancer patients. RESULTS: 5-FU uptake into pooled primary BMC was both time and concentration dependent. An Eadie-Hofstee analysis suggested two components; a high-affinity (KM = 3.3 µM) low-capacity ([Formula: see text] = 57.8 pmol min-1 105 viable cells-1) transporter, and a high-capacity ([Formula: see text] = 1230 pmol min-1 105 viable cells-1) low-affinity (KM = 3932 µM) transporter. There was 180-fold variation in the rate of 5-FU uptake into BMC (0.10-17.86 pmol min-1 105 viable cells-1) across the 34 subjects (healthy participants N = 24, cancer patients N = 10). Notably, retesting of a subset of these participants (N = 16) multiple times over a period of up to 140 days demonstrated poor stability of the uptake phenotype within individuals. CONCLUSION: The uptake of 5-FU into healthy oral mucosal cells is a highly variable process facilitated by membrane transporters at pharmacologically relevant concentrations. This bioassay is simple, minimally invasive, and suitable for phenotypic analysis of drug transport in healthy primary cells.
PURPOSE:Fluorouracil (5-FU), a chemotherapeutic agent widely used in the treatment of numerous common malignancies, causes oral mucositis in a proportion of patients. The contribution of drug transport processes to the development of this toxicity is currently unknown. This work aimed to establish and optimise a simple phenotyping assay for 5-FU uptake into primary buccal mucosal cells (BMC). METHODS: The uptake kinetics of radiolabelled 5-FU were determined in pooled BMC freshly collected from healthy volunteers. The inter- and intra-individual variability in 5-FU uptake was then assessed across a cohort that included both healthy volunteers and cancerpatients. RESULTS:5-FU uptake into pooled primary BMC was both time and concentration dependent. An Eadie-Hofstee analysis suggested two components; a high-affinity (KM = 3.3 µM) low-capacity ([Formula: see text] = 57.8 pmol min-1 105 viable cells-1) transporter, and a high-capacity ([Formula: see text] = 1230 pmol min-1 105 viable cells-1) low-affinity (KM = 3932 µM) transporter. There was 180-fold variation in the rate of 5-FU uptake into BMC (0.10-17.86 pmol min-1 105 viable cells-1) across the 34 subjects (healthy participants N = 24, cancerpatients N = 10). Notably, retesting of a subset of these participants (N = 16) multiple times over a period of up to 140 days demonstrated poor stability of the uptake phenotype within individuals. CONCLUSION: The uptake of 5-FU into healthy oral mucosal cells is a highly variable process facilitated by membrane transporters at pharmacologically relevant concentrations. This bioassay is simple, minimally invasive, and suitable for phenotypic analysis of drug transport in healthy primary cells.
Entities:
Keywords:
5-Fluorouracil; Cancer pharmacology; Drug toxicity; Drug transport; Mucosal cells; Phenotype
Authors: Nuala A Helsby; John Duley; Kathryn E Burns; Claire Bonnet; Soo Hee Jeong; Elliott Brenman; Paula Barlow; Katrina Sharples; David Porter; Michael Findlay Journal: Br J Clin Pharmacol Date: 2019-12-12 Impact factor: 4.335