Expression of recombinant human multidrug resistance P-glycoprotein in insect cells confers decreased accumulation of technetium-99m-sestamibi.

V V Rao; M L Chiu; J F Kronauge; D Piwnica-Worms

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PubMed · 7906729

Expression of recombinant human multidrug resistance P-glycoprotein in insect cells confers decreased accumulation of technetium-99m-sestamibi.

V V Rao·M L Chiu·J F Kronauge·D Piwnica-Worms

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Abstract

UNLABELLED: The multidrug-resistant P-glycoprotein is a M(r) 170,000 plasma membrane protein encoded by the mammalian multidrug resistance gene (MDR) which appears to function as an efflux transporter of a variety of potent chemotherapeutic agents. METHODS: To directly demonstrate that 99mTc-sestamibi is recognized by the human P-glycoprotein, we overexpressed recombinant human MDR1 P-glycoprotein in host Sf9 insect cells using a baculoviral vector and correlated expression of the gene product with 99mTc-sestamibi accumulation. RESULTS: In parental Sf9 cells and in wild-type baculoviral infected (control) cells, 99mTc-sestamibi accumulation asymptotically approached a plateau of 650 fmoles (mg protein)-1 (nMo)-1 and 337 fmoles (mg protein)-1 (nMo)-1, respectively. In MDR1 baculoviral infected cells, P-glycoprotein expression was maximal at 72 hr postinfection, while 99mTc-sestamibi accumulation was reduced to 12 fmole (mg protein)-1 (nMo)-1. Verapamil (500 microM), the classical MDR modulator, produced an approximately 300% enhancement of 99mTc-sestamibi accumulation in Sf9 cells expressing MDR1 P-glycoprotein, but only a 50% enhancement in parental Sf9 cells, consistent with verapamil-induced inhibition of P-glycoprotein-mediated 99mTc-sestamibi efflux. CONCLUSIONS: These data demonstrate that the recombinant protein is transiently expressed in a functional state capable of drug transport in Sf9 cell membranes and that 99mTc-sestamibi is a transport substrate recognized by the human MDR1 P-glycoprotein. Technetium-99m-sestamibi may prove useful for functionally characterizing P-glycoprotein expression in human tumors in vivo.

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ATP Binding Cassette Transporter, Subfamily B, Member 1 Animals Baculoviridae Blotting, Western Carrier Proteins Cells, Cultured Drug Resistance Gene Expression Humans Membrane Glycoproteins Moths Technetium Tc 99m Sestamibi Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S.

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V V Rao, M L Chiu, J F Kronauge, D Piwnica-Worms. 1994. Expression of recombinant human multidrug resistance P-glycoprotein in insect cells confers decreased accumulation of technetium-99m-sestamibi.. https://pubmed.ncbi.nlm.nih.gov/7906729/

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