Related Experiment Video
Updated: Aug 9, 2026

The Use of Reverse Phase Protein Arrays (RPPA) to Explore Protein Expression Variation within Individual Renal Cell Cancers
Published on: January 22, 2013
Verapamil modulation of multidrug resistance in renal cell carcinoma
1Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Background And Purpose:
Renal cell carcinoma (RCC) is well known for its chemoresistance. The membranous p-glycoprotein (gp-170) is believed to be highly correlated with multidrug resistance (MDR) of cancer cells with energy-dependent pumping efflux of anticancer drugs. Verapamil, a calcium antagonist, inhibits the efflux function of gp-170 and cytoskeletal transportation. The aim of this study was to determine the effect of verapamil on gp-170 expression and intracellular drug accumulation in RCC tumor cells and the modulation of cytotoxicity of various chemotherapeutic drugs on native RCC cell lines and acquired MDR sublines by verapamil.
Methods:
Using cultured cell lines of RCC and their MDR sublines as target cells, the effect of verapamil on gp-170 expression was analyzed by immunofluorescence flow cytometry. The influence of verapamil on intracellular drug accumulation in RCC tumor cells was measured by autofluorescence flow cytometry. The modulation of verapamil on cytotoxicity of various chemotherapeutic drugs on native RCC cell lines and acquired MDR sublines was analyzed by the methyl tetrazolium method.
Results:
From flow cytometric measurement, the expression of gp-170 was significantly decreased in A704 and Caki-1 tumor cells after verapamil treatment. The uptake of adriamycin and maintenance of intracellular drugs were also significantly increased following verapamil treatment in RCC8701 tumor cells. These effects were sustained for as long as 8 hours after verapamil withdrawal. The cytotoxicity of adriamycin and epirubicin on RCC8701 and its MDR subline tumor cells was markedly intensified by verapamil. The verapamil modulation of cytotoxicity was in an immediate-reaction pattern and was dose-dependent, with synergistic effects. Long-term treatment was more effective than short-term treatment in RCC MDR sublines. The cytotoxicity of vinca alkaloid (vinblastine) and alkylators (carboplatin) was also enhanced by verapamil.
Conclusions:
These results suggest that verapamil plays an important role in the circumvention of native and acquired chemoresistance of RRC because it suppresses membranous gp-170 expression and cytoplasmic drug transportation.
More Related Videos
Related Concept Videos
Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
Heart Failure Drugs: Inhibitors of Renin-Angiotensin System
Antianginal Drugs: Calcium Channel Blockers and Ranolazine
CCBs, a diverse class that includes dihydropyridines (nifedipine) and diphenylalkylamines (verapamil and diltiazem), exert their effect by blocking calcium channels in cardiac and smooth muscle cells. This...
Antiepileptic Drugs: Modulators of Neurotransmitter Release Mediated by SV2A Protein
SV2A is a transmembrane glycoprotein located predominantly in the brain, modulating the release of neurotransmitters for neuronal communication. Both levetiracetam and brivaracetam exhibit a high affinity for...
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase

