Contribution of Organic Anion-Transporting Polypeptides 1A/1B to Doxorubicin Uptake and Clearance
Hannah H Lee1, Brenda F Leake1, Richard B Kim1
1Division of Hematology and Oncology, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee (H.H.L., B.F.L., R.H.H.); and Division of Clinical Pharmacology, Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada (R.B.K.).
Abstract:
The organic anion-transporting polypeptides represent an important family of drug uptake transporters that mediate the cellular uptake of a broad range of substrates including numerous drugs. Doxorubicin is a highly efficacious and well-established anthracycline chemotherapeutic agent commonly used in the treatment of a wide range of cancers. Although doxorubicin is a known substrate for efflux transporters such as P-glycoprotein (P-gp; MDR1, ABCB1), significantly less is known regarding its interactions with drug uptake transporters. Here, we investigated the role of organic anion transporting polypeptide (OATP) transporters to the disposition of doxorubicin. A recombinant vaccinia-based method for expressing uptake transporters in HeLa cells revealed that OATP1A2, but not OATP1B1 or OATP1B3, and the rat ortholog Oatp1a4 were capable of significant doxorubicin uptake. Interestingly, transwell assays using Madin-Darby canine kidney II cell line cells stably expressing specific uptake and/or efflux transporters revealed that OATP1B1, OATP1B3, and OATP1A2, either alone or in combination with MDR1, significantly transported doxorubicin. An assessment of polymorphisms in SLCO1A2 revealed that four variants were associated with significantly impaired doxorubicin transport in vitro. In vivo doxorubicin disposition studies revealed that doxorubicin plasma area under the curve was significantly higher (1.7-fold) in Slco1a/1b-/- versus wild-type mice. The liver-to-plasma ratio of doxorubicin was significantly decreased (2.3-fold) in Slco1a/1b2-/- mice and clearance was reduced by 40% compared with wild-type mice, suggesting Oatp1b transporters are important for doxorubicin hepatic uptake. In conclusion, we demonstrate important roles for OATP1A/1B in transporter-mediated uptake and disposition of doxorubicin.
Insights
Organic anion-transporting polypeptides (OATPs) facilitate doxorubicin uptake. OATP1A2, OATP1B1, and OATP1B3 significantly transport doxorubicin, impacting its disposition and clearance. Genetic variants in OATP1A2 impair transport.
Area of Science:
- Pharmacology
- Molecular Biology
- Biochemistry
Background:
- Organic anion-transporting polypeptides (OATPs) are crucial for drug uptake.
- Doxorubicin, a key chemotherapy drug, is known to interact with efflux transporters like P-glycoprotein (P-gp).
- The role of OATPs in doxorubicin cellular uptake and disposition remains less understood.
Purpose of the Study:
- To investigate the involvement of OATP transporters in the cellular uptake and disposition of doxorubicin.
- To identify specific OATP isoforms responsible for doxorubicin transport.
- To assess the impact of OATP genetic variations and in vivo transporter knockout on doxorubicin pharmacokinetics.
Main Methods:
- Utilized a recombinant vaccinia-based expression system in HeLa cells to assess doxorubicin uptake by OATP isoforms.
- Employed transwell assays with Madin-Darby canine kidney II cells expressing OATPs and MDR1 to study doxorubicin transport.
- Analyzed the impact of SLCO1A2 polymorphisms on doxorubicin transport in vitro.
- Conducted in vivo doxorubicin disposition studies in wild-type and Slco1a/1b knockout mice.
Main Results:
- OATP1A2, but not OATP1B1 or OATP1B3, showed significant doxorubicin uptake in initial expression studies.
- Transwell assays confirmed that OATP1B1, OATP1B3, and OATP1A2 mediate significant doxorubicin transport, alone or with MDR1.
- Four SLCO1A2 variants were associated with impaired in vitro doxorubicin transport.
- In vivo, doxorubicin exposure (AUC) was higher in Slco1a/1b knockout mice, with reduced liver uptake and clearance, indicating Oatp1b's role in hepatic uptake.
Conclusions:
- OATP1A2, OATP1B1, and OATP1B3 play significant roles in the cellular uptake of doxorubicin.
- Oatp1b transporters are important for the hepatic uptake and disposition of doxorubicin in vivo.
- Genetic variations in OATPs can influence doxorubicin transport and potentially affect its therapeutic efficacy and toxicity.
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