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Updated: Aug 16, 2026
Using Caco-2 Cells to Study Lipid Transport by the Intestine
Published on: August 20, 2015
Construction of a functional transporter analysis system using MDR1 knockdown Caco-2 cells
Tomoko Watanabe1, Reiko Onuki, Shinji Yamashita
1Department of Molecular Pharmacokinetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Purpose:
The efflux transporter, P-glycoprotein (P-gp), located in the brush-border membrane of intestinal absorptive cells, reduces the bioavailability of a wide range of orally administered drugs. Using P-gp inhibitors in transport experiments in Caco-2 cell monolayers is widely accepted as an efficient way to estimate the contribution of P-gp to the intestinal absorption of drugs. However, there still remain some arguments that the inhibitors might affect the function of other proteins. Multidrug resistance 1 gene (MDR1) specifically inhibited Caco-2 cells were constructed, therefore, as a better in vitro evaluation system of intestinal drug absorption.
Methods:
The effective sites of RNAi were selected using siRNA libraries and single siRNAs and MDR1 stable knockdown Caco-2 cells were constructed using a tRNA(val)-shRNA expression vector.
Results:
In siRNA stably expressed Caco-2 cells, the expression level of MDR1 was reduced at mRNA and protein levels. Transcellular transport studies using digoxin revealed that the P-gp function was suppressed completely, similar to that in verapamil-treated cells.
Conclusions:
MDR1 stable knockdown Caco-2 cells were successfully constructed by RNAi technology. This will consequently allow the development of a selection system for candidate drugs with improved absorption properties.
Insights
Researchers developed a new in vitro model using Multidrug Resistance 1 gene (MDR1) knockdown Caco-2 cells to accurately assess drug absorption. This system effectively suppresses P-glycoprotein (P-gp) function, improving drug development evaluations.
Area of Science:
- Pharmacology
- Cell Biology
- Drug Discovery
Background:
- P-glycoprotein (P-gp) limits oral drug bioavailability by actively transporting drugs out of intestinal cells.
- Current in vitro models using P-gp inhibitors may affect other cellular functions.
- A more specific method is needed to evaluate P-gp's role in drug absorption.
Purpose of the Study:
- To develop and validate a novel in vitro model for assessing intestinal drug absorption.
- To create Caco-2 cells with specifically inhibited Multidrug Resistance 1 gene (MDR1) expression.
- To establish a reliable system for evaluating drug absorption influenced by P-gp.
Main Methods:
- Utilized RNA interference (RNAi) technology with siRNA libraries and single siRNAs.
- Constructed stable MDR1 knockdown Caco-2 cell lines using a tRNA(val)-shRNA expression vector.
- Performed transcellular transport studies using digoxin to assess P-gp function.
Main Results:
- Successfully reduced MDR1 gene expression at both mRNA and protein levels in engineered Caco-2 cells.
- Demonstrated complete suppression of P-gp function in these cells, comparable to verapamil treatment.
- Validated the efficacy of the MDR1 knockdown model in inhibiting P-gp activity.
Conclusions:
- Achieved successful construction of MDR1 stable knockdown Caco-2 cells via RNAi.
- This novel cell line provides a superior in vitro system for evaluating intestinal drug absorption.
- Enables the development of a selection system for candidate drugs with enhanced absorption profiles.
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