Expression and function of P-glycoprotein in a mouse kidney cell line

Area of Science:

• Pharmacology
• Nephrology
• Molecular Biology

Background:

• P-glycoprotein (PGP) is a transporter protein that confers multidrug resistance in cancer cells.
• PGP is expressed in the kidney, specifically in proximal tubules and mesangium.
• A mouse kidney proximal tubule cell line (TKPTS) expressing PGP was established.

Purpose of the Study:

• To investigate the role and inhibition of PGP in kidney cells.
• To assess the impact of PGP inhibition on drug accumulation and transport.
• To explore the potential of PGP inhibition as a strategy to overcome multidrug resistance and understand renal toxicity.

Main Methods:

• Utilized C219 monoclonal antibody for PGP detection in mouse kidneys.
• Established and characterized a PGP-expressing cell line (TKPTS).
• Employed Northern blot and ribonuclease protection assays to identify the mdr1 message.
• Assessed the effects of Cyclosporin A (CSA) and Verapamil (VRP) on cellular accumulation of various substrates (VRP, CSA, vinblastine, Rhodamine-123).
• Evaluated the impact of PGP inhibitors (VRP, CSA, PSC-833) on the efficacy of adriamycin.

Main Results:

• PGP was localized to proximal tubules and mesangium in mouse kidneys.
• CSA and VRP significantly increased the cellular accumulation of PGP substrates.
• VRP inhibited the basal-to-apical transport of vinblastine.
• Rhodamine-123 influx was PGP-independent, but efflux was inhibited by VRP and CSA.
• Inhibition of PGP by VRP, CSA, and PSC-833 reduced the effective dose of adriamycin.
• Concomitant administration of VRP and CSA showed no adverse effects and preferential VRP accumulation.

Conclusions:

• PGP-mediated transport plays a role in renal cells.
• Inhibiting PGP can enhance the accumulation of drugs and potentially overcome multidrug resistance.
• PGP inhibition is implicated as a mechanism contributing to renal cell toxicity.