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Involvement of organic cation transporter 1 and CYP3A4 in retrorsine-induced toxicity

Meijuan Tu1, Liping Li1, Hongmei Lei1

  • 1Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China.

Toxicology
|May 7, 2014
PubMed

Insights

Retrorsine (RTS) is a liver toxin. Organic cation transporter 1 (OCT1) and cytochrome P450 3A4 (CYP3A4) mediate RTS uptake and toxicity. OCT1 inhibitors may protect the liver from RTS damage.

Area of Science:

  • Pharmacology and Toxicology
  • Drug Metabolism and Transport

Background:

  • Retrorsine (RTS) is a hepatotoxic pyrrolizidine alkaloid found in Senecio plants.
  • The liver's role in RTS disposition and the mechanisms of its toxicity are not fully understood.

Purpose of the Study:

  • To elucidate the role of organic cation transporters (OCTs) in the liver uptake of RTS.
  • To investigate the interplay between OCT1 and cytochrome P450 3A4 (CYP3A4) in RTS-induced hepatotoxicity.

Main Methods:

  • Utilized cell lines (MDCK, LLC-PK1) expressing various transporters to study RTS interactions.
  • Employed primary cultured rat hepatocytes (PCRH) and double-transfected MDCK-hOCT1-CYP3A4 cells to assess toxicity.
  • Investigated RTS inhibition of OCT1-mediated substrate uptake and the effects of OCT1 inhibitors on RTS toxicity.

Main Results:

  • RTS inhibited OCT1-mediated uptake of 1-methyl-4-phenylpyridinium (MPP+) with an IC50 of 2.25±0.30μM.
  • OCT1 inhibitors significantly reduced RTS uptake in cells and attenuated RTS-induced toxicity in primary hepatocytes.
  • RTS exhibited increased toxicity in cells co-expressing OCT1 and CYP3A4, suggesting a synergistic effect.

Conclusions:

  • OCT1 is crucial for the liver-specific uptake of RTS.
  • OCT1 and CYP3A4 collaboratively contribute to RTS-induced hepatotoxicity.
  • OCT1 inhibitors show potential as a therapeutic strategy to mitigate liver damage from RTS.
Keywords:
CYP3A4Double-transfected cellsHepatotoxicityOrganic cation transporter 1RetrorsineTransporters

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