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Sorafenib Activity and Disposition in Liver Cancer Does Not Depend on Organic Cation Transporter 1.

ABSTRACT: Systemic therapy of advanced hepatocellular carcinoma (HCC) with the small-molecule multikinase inhibitor sorafenib is associated with large interindividual pharmacokinetic variability and unpredictable side effects potentially requiring dose reduction or treatment termination. Organic cation transporter (OCT1; gene SLC22A1) has been proposed as a clinical biomarker of HCC response. Because proof is lacking that OCT1 transports sorafenib, we used a combinatorial approach to define how OCT1 contributes to sorafenib transport. Overexpression of functional OCT1 protein in Xenopus laevis oocytes and mammalian cell lines did not facilitate sorafenib transport. Otherwise, sorafenib considerably accumulated in liver cancer cell lines despite negligible OCT1 mRNA and protein levels. Sorafenib pharmacokinetics was independent of OCT1 genotype in mice. Finally, SLC22A1 mRNA expression was significantly reduced by DNA methylation in The Cancer Genome Atlas HCC cohort. These results clearly demonstrate OCT1-independent cellular sorafenib uptake indicating that OCT1 is apparently not a valid biomarker of sorafenib response in HCC.

SUBMITTER: Chen M

PROVIDER: S-EPMC6925656 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Sorafenib Activity and Disposition in Liver Cancer Does Not Depend on Organic Cation Transporter 1.

Chen Mingqing M Neul Claudia C Schaeffeler Elke E Frisch Franziska F Winter Stefan S Schwab Matthias M Koepsell Hermann H Hu Shuiying S Laufer Stefan S Baker Sharyn D SD Sparreboom Alex A Nies Anne T AT

Clinical pharmacology and therapeutics 20190903 1

Systemic therapy of advanced hepatocellular carcinoma (HCC) with the small-molecule multikinase inhibitor sorafenib is associated with large interindividual pharmacokinetic variability and unpredictable side effects potentially requiring dose reduction or treatment termination. Organic cation transporter (OCT1; gene SLC22A1) has been proposed as a clinical biomarker of HCC response. Because proof is lacking that OCT1 transports sorafenib, we used a combinatorial approach to define how OCT1 contr ...[more]

PMID: 31350763

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Project description:The organic cation transporter (OCT) 3 is widely expressed in various organs in humans, and involved in the disposition of many exogenous and endogenous compounds. Several lines of evidence have suggested that OCT3 expressed in the brain plays an important role in the regulation of neurotransmission. Relative to wild-type (WT) animals, Oct3 knockout (KO) mice have displayed altered behavioral and neurochemical responses to psychostimulants such as amphetamine (AMPH) and methamphetamine. In the present study, both in vitro and in vivo approaches were utilized to explore potential mechanisms underlying the disparate neuropharmacological effects observed following AMPH exposure in Oct3 KO mice. In vitro uptake studies conducted in OCT3 transfected cells indicated that dextroamphetamine (d-AMPH) is not a substrate of OCT3. However, OCT3 was determined to be a high-capacity and low-affinity transporter for the neurotransmitters dopamine (DA), norepinephrine (NE), and serotonin (5-HT). Inhibition studies demonstrated that d-AMPH exerts relatively weak inhibitory effects on the OCT3-mediated uptake of DA, NE, 5-HT, and the model OCT3 substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide. The IC(50) values were determined to be 41.5 +/- 7.5 and 24.1 +/- 7.0 microM for inhibiting DA and 5-HT uptake, respectively, while 50% inhibition of NE and 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide uptake was not achieved by even the highest concentration of d-AMPH applied (100 microM). Furthermore, the disposition of d-AMPH in various tissues including the brain, liver, heart, kidney, muscle, intestine, spleen, testis, uterus, and plasma were determined in both male and female Oct3 KO and WT mice. No significant difference was observed between either genotypes or sex in all tested organs and tissues. Our findings suggest that OCT3 is not a prominent factor influencing the disposition of d-AMPH. Additionally, based upon the inhibitory potency observed in vitro, d-AMPH is unlikely to inhibit the uptake of monoamines mediated by OCT3 in the brain. Differentiated neuropharmacological effects of AMPHs noted between Oct3 KO and WT mice appear to be due to the absence of Oct3 mediated uptake of neurotransmitters in the KO mice.

Project description:IntroductionWe evaluated chr6q25.3 organic cation transporter gene (SLC22A1, SLC22A2, SLC22A3) variation and response to smoking cessation therapies. The corresponding proteins are low-affinity transporters of choline, acetylcholine and monoamines, and smoking cessation pharmacotherapies expressed in multiple tissues.MethodsWe selected 7 common polymorphisms for mega-regression analysis. We assessed additive model association of polymorphisms with 7-day point prevalence abstinence overall and by assigned pharmacotherapy at end of treatment and at 6 months among European-ancestry participants of 7 randomized controlled trials adjusted for demographic, population genetic, and trial covariates.ResultsInitial results were obtained in 6 trials with 1,839 participants. Nominally statistically significant associations of 2 SLC22A2 polymorphisms were observed: (1) with rs316019 at 6 months, overall ([c.808T>G; p.Ser270Ala], OR = 1.306, 95% CI = 1.034-1.649, p = .025), and among those randomized to nicotine replacement therapy (NRT) (OR = 1.784, 95% CI = 1.072-2.970, p = .026); and (2) with rs316006 (c.1502-529A>T) among those randomized to varenicline (OR = 1.420, 95% CI = 1.038-1.944, p = .028, OR = 1.362, 95% CI = 1.001-1.853, p = .04) at end of treatment and 6 months. Individuals randomized to NRT from a seventh trial were genotyped for rs316019; rs316019 was associated with a nominally statistically significant effect on abstinence overall at 6 months among 2,233 participants (OR = 1.249, 95% CI = 1.007-1.550, p = .043).ConclusionsThe functional OCT2 Ser270Ala polymorphism is nominally statistically significantly associated with abstinence among European-ancestry treatment-seeking smokers after adjustments for pharmacotherapy, demographics, population genetics, and without adjustment for multiple testing of 7 SNPs. Replication of these preliminary findings in additional randomized controlled trials of smoking cessation therapies and from multiple continental populations would describe another pharmacogenetic role for SLC22A2/OCT2.

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Sorafenib Activity and Disposition in Liver Cancer Does Not Depend on Organic Cation Transporter 1.

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Sorafenib Activity and Disposition in Liver Cancer Does Not Depend on Organic Cation Transporter 1.

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