Abstract
The TT-cell line, derived from a patient with metastatic medullary thyroid carcinoma (MTC), was found to exhibit intrinsic resistance to vincristine (VCR) despite the absence of immunohistochemically detectable 170 kDa P-glycoprotein (PGP 170) associated with multidrug resistance (MDR). Verapamil and cyclosporin A, two well known resistance modifiers of MDR, were found to significantly potentiate the action of VCR (60-fold) and to a lesser degree also of VP-16 and daunorubicin (dnr). The present results suggests that resistance of MTC to chemotherapy may be at least partly circumvented by the addition resistance modifiers to chemotherapeutic regimens.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ATP Binding Cassette Transporter, Subfamily B, Member 1
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Cyclosporins / pharmacology*
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Daunorubicin / pharmacology
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Dose-Response Relationship, Drug
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Drug Resistance
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Drug Synergism
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Etoposide / pharmacology
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Humans
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Membrane Glycoproteins / metabolism
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Membrane Glycoproteins / physiology
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Thyroid Neoplasms / drug therapy*
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Thyroid Neoplasms / metabolism
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Thyroid Neoplasms / pathology
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Tumor Cells, Cultured
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Verapamil / pharmacology*
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Vincristine / pharmacology
Substances
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ATP Binding Cassette Transporter, Subfamily B, Member 1
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Cyclosporins
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Membrane Glycoproteins
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Vincristine
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Etoposide
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Verapamil
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Daunorubicin