Modulation of the function of the multidrug resistance–linked ATP-binding cassette transporter ABCG2 by the cancer chemopreventive agent curcumin

Wanida Chearwae,Suneet Shukla,Suresh V Ambudkar,Pornngarm Limtrakul

doi:10.1158/1535-7163.mct-06-0087

Wanida Chearwae, Suneet Shukla + Show 2 more

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https://doi.org/10.1158/1535-7163.mct-06-0087

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Abstract

Curcumin (curcumin I), demethoxycurcumin (curcumin II), and bisdemethoxycurcumin (curcumin III) are the major forms of curcuminoids found in the turmeric powder, which exhibit anticancer, antioxidant, and anti-inflammatory activities. In this study, we evaluated the ability of purified curcuminoids to modulate the function of either the wild-type 482R or the mutant 482T ABCG2 transporter stably expressed in HEK293 cells and drug-selected MCF-7 FLV1000 and MCF-7 AdVp3000 cells. Curcuminoids inhibited the transport of mitoxantrone and pheophorbide a from ABCG2-expressing cells. However, both cytotoxicity and [(3)H]curcumin I accumulation assays showed that curcuminoids are not transported by ABCG2. Nontoxic concentration of curcumin I, II, and III sensitized the ABCG2-expressing cells to mitoxantrone, topotecan, SN-38, and doxorubicin. This reversal was not due to reduced expression because ABCG2 protein levels were unaltered by treatment with 10 mumol/L curcuminoids for 72 hours. Curcumin I, II, and III stimulated (2.4- to 3.3-fold) ABCG2-mediated ATP hydrolysis and the IC(50)s were in the range of 7.5 to 18 nmol/L, suggesting a high affinity of curcuminoids for ABCG2. Curcuminoids also inhibited the photolabeling of ABCG2 with [(125)I]iodoarylazidoprazosin and [(3)H]azidopine as well as the transport of these two substrates in ABCG2-expressing cells. Curcuminoids did not inhibit the binding of [alpha-(32)P]8-azidoATP to ABCG2, suggesting that they do not interact with the ATP-binding site of the transporter. Collectively, these data show that, among curcuminoids, curcumin I is the most potent modulator of ABCG2 and thus should be considered as a treatment to increase the efficacy of conventional chemotherapeutic drugs.

Highlights

Development of multidrug resistance (MDR) is a problem in cancer chemotherapy that limits the effectiveness of anticancer drugs [1, 2]
We have shown previously that curcuminoids are inhibitors of the ATP-binding cassette (ABC) transporters, ABCB1 [25, 26] and ABCC1 [27], which are known to play a major role in the development of MDR in cancer cells
The curcuminoids inhibited the transport of the substrates from ABCG2expressing cells (Fig. 1; Table 1) and the maximal inhibition was comparable with 10 Amol/L fumitremorgin C, a potent inhibitor of ABCG2 [12]

Summary

Introduction

Development of multidrug resistance (MDR) is a problem in cancer chemotherapy that limits the effectiveness of anticancer drugs [1, 2]. The overexpression of ATP-binding cassette (ABC) transporters, such as ABCB1 (P-glycoprotein) and ABCC1 (MRP1), have been shown to confer resistance to chemotherapeutic agents by exporting drugs from cells in an ATP-dependent manner. ABCG2 ( called mitoxantrone resistance-associated protein, breast cancer resistance protein, and placental ABC transporter) is a half-transporter of the ABCG subfamily of ABC transporters, the overexpression of which plays a major role in the development of the MDR phenotype of malignant cells (3 – 6). It confers resistance to various anticancer agents, such as doxorubicin, mitoxantrone, topotecan, and SN-38 (7 – 10). The neurotoxic effects of fumitremorgin C and its structural analogues precluded its use as a modulator for in vivo studies (13 – 15)

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