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The human organic cation transporter OCT1 and its role as a target for drug responses
Nicolas Brosseau1, Dindial Ramotar1
1Department of Medicine, Maisonneuve-Rosemont Hospital, Research Center, Université de Montréal, Montréal, Québec, Canada.
Abstract:
The human organic cation uptake transporter OCT1, encoded by the SLC22A1 gene, is highly expressed in the liver and reported to possess a broad substrate specificity. OCT1 operates by facilitated diffusion and allows the entry of nutrients into cells. Recent findings revealed that OCT1 can mediate the uptake of drugs for treating various diseases such as cancers. The levels of OCT1 expression correlate with the responses towards many drugs and functionally defective OCT1 lead to drug resistance. It has been recently proposed that OCT1 should be amongst the crucial drug targets used for pharmacogenomic analyses. Several single nucleotide polymorphisms exist and are distributed across the entire OCT1 gene. While there are differences in the OCT1 gene polymorphisms between populations, there are at least five variants that warrant consideration in any genetic screen. To date, and despite two decades of research into OCT1 functional role, it still remains uncertain what are the define substrates for this uptake transporter, although studies from mice revealed that one of the substrates is vitamin B1. It is also unclear how OCT1 recognizes a broad array of ligands and whether this involves specific modifications and interactions with other proteins. In this review, we highlight the current findings related to OCT1 with the aim of propelling further studies on this key uptake transporter.
Insights
The organic cation transporter OCT1 (SLC22A1) is crucial for drug uptake and response, particularly in cancer treatment. Understanding its broad substrate specificity and genetic variants is key for personalized medicine and overcoming drug resistance.
Area of Science:
- Pharmacology
- Genetics
- Cell Biology
Background:
- The organic cation transporter 1 (OCT1), encoded by SLC22A1, is highly expressed in the liver.
- OCT1 facilitates the cellular uptake of various molecules, including essential nutrients and therapeutic drugs.
- Its expression levels are linked to drug efficacy and resistance, especially in cancer treatment.
Purpose of the Study:
- To review current findings on OCT1's role in drug transport and pharmacogenomics.
- To highlight the significance of OCT1 in personalized medicine and drug development.
- To identify knowledge gaps and propose future research directions for OCT1.
Main Methods:
- Literature review of studies on OCT1 function, substrate specificity, and genetic variations.
- Analysis of the correlation between OCT1 expression/polymorphisms and drug response.
- Synthesis of data regarding OCT1's role in nutrient and drug uptake mechanisms.
Main Results:
- OCT1 exhibits broad substrate specificity, mediating the uptake of drugs used in various diseases, including cancer.
- Functional OCT1 variants and polymorphisms are associated with significant differences in drug response and resistance.
- Vitamin B1 has been identified as a substrate in mouse models, but definitive substrates in humans remain unclear.
Conclusions:
- OCT1 is a critical target for pharmacogenomic studies due to its role in drug response.
- Further research is needed to elucidate OCT1's precise substrate recognition mechanisms and protein interactions.
- Understanding OCT1 variants and function is essential for optimizing drug therapy and overcoming resistance.
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