Photoaffinity labeling of the multidrug-resistance-related P-glycoprotein with photoactive analogs of verapamil

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.85.19.7187· OSTI ID:5607107

Safa, A R ^[1]

---

1. Univ. of Chicago Medical Centers, IL (USA)

Verapamil, a phenylalkylamine calcium channel blocker, has been shown to reverse multidrug resistance in tumor cells, possibly by increasing drug retention through interaction with an outward drug transporter of the resistant cells. In this study two photoactive radioactive analogs of verapamil, N-(p-azido(3,5-{sup 3}H)benzoyl)aminomethyl verapamil and N-(p-azido(3-{sup 125}I)salicyl)aminomethyl verapamil, were synthesized and used to identify the possible biochemical target(s) for verapamil in multidrug-resistance DC-3F/VCRd-5L Chinese hamster lung cells selected for resistance to vincristine. The results show that a specifically labeled 150- to 180-kDa membrane protein in resistant cells was immunoprecipitated with a monoclonal antibody specific for P-glycoprotein. Phenylalkylamine binding specificity was established by competitive blocking of specific photolabeling with the nonradioactive photoactive analogs as well as with verapamil. Photoaffinity labeling was also inhibited by 50 {mu}M concentrations of the calcium channel blockers nimodipine, nifedipine, nicardipine, azidopine, bepridil, and diltiazem and partially by prenylamine. Moreover, P-glycoprotein labeling was inhibited in a dose-dependent manner by vinblastine with half-maximal inhibition at 0.2 {mu}M compared to that by verapamil at 8 {mu}M. These data provide direct evidence that P-glycoprotein has broad drug recognition capacity and that it serves as a molecular target for calcium channel blocker action in reversing multidrug resistance.

• OSTI ID: 5607107
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 85:19; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AMINES
BIOSYNTHESIS
DRUGS
SENSITIVITY
GLUCOPROTEINS
LABELLING
ACTINOMYCIN
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
DOXORUBICIN
ELECTROPHORESIS
FIBROBLASTS
HAMSTERS
IODINE 125
LUNGS
MONOCLONAL ANTIBODIES
TRITIUM COMPOUNDS
VINBLASTINE
ALKALOIDS
ANIMAL CELLS
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTIBODIES
ANTIMITOTIC DRUGS
ANTINEOPLASTIC DRUGS
AROMATICS
AZAARENES
AZOLES
BETA DECAY RADIOISOTOPES
BODY
CARBOHYDRATES
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
GLYCOPROTEINS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INDOLES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
KINETICS
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PROTEINS
PYRROLES
RADIOISOTOPES
REACTION KINETICS
RESPIRATORY SYSTEM
RODENTS
SACCHARIDES
SOMATIC CELLS
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques