Dataset Information

Increased [¹⁸F]FMISO accumulation under hypoxia by multidrug-resistant protein 1 inhibitors.

ABSTRACT:

Background

[¹⁸F]Fluoromisonidazole ([¹⁸F]FMISO) is a PET imaging probe widely used for the detection of hypoxia. We previously reported that [¹⁸F]FMISO is metabolized to the glutathione conjugate of the reduced form in hypoxic cells. In addition, we found that the [¹⁸F]FMISO uptake level varied depending on the cellular glutathione conjugation and excretion ability such as enzyme activity of glutathione-S-transferase and expression levels of multidrug resistance-associated protein 1 (MRP1, an efflux transporter), in addition to the cellular hypoxic state. In this study, we evaluated whether MRP1 activity affected [¹⁸F]FMISO PET imaging.

Methods

FaDu human pharyngeal squamous cell carcinoma cells were pretreated with MRP1 inhibitors (cyclosporine A, lapatinib, or MK-571) for 1 h, incubated with [¹⁸F]FMISO for 4 h under hypoxia, and their radioactivity was then measured. FaDu tumor-bearing mice were intravenously injected with [¹⁸F]FMISO, and PET/CT images were acquired at 4 h post-injection (1st PET scan). Two days later, the same mice were pretreated with MRP1 inhibitors (cyclosporine A, lapatinib, or MK-571) for 1 h, and PET/CT images were acquired (2nd PET scan).

Results

FaDu cells pretreated with MRP1 inhibitors exhibited significantly higher radioactivity than those without inhibitor treatment (cyclosporine A: 6.91?±?0.27, lapatinib: 10.03?±?0.47, MK-571: 10.15?±?0.44%dose/mg protein, p?mean ratio in tumors [calculated as after treatment (2nd PET scan)/before treatment of MRP1 inhibitors (1st PET scan)] of the mice treated with MRP1 inhibitors was significantly higher than those of control mice (cyclosporine A: 2.6?±?0.7, lapatinib: 2.2?±?0.7, MK-571: 2.2?±?0.7, control: 1.2?±?0.2, p?ConclusionIn this study, we revealed that MRP1 inhibitors increase [¹⁸F]FMISO accumulation in hypoxic cells. This suggests that [¹⁸F]FMISO-PET imaging is affected by MRP1 inhibitors independent of the hypoxic state.

SUBMITTER: Shimizu Y

PROVIDER: S-EPMC7835267 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Increased [18F]FMISO accumulation under hypoxia by multidrug-resistant protein 1 inhibitors.

Shimizu Yoichi Y Nakai Yukihiro Y Watanabe Hiroyuki H Iikuni Shimpei S Ono Masahiro M Saji Hideo H Kuge Yuji Y Saga Tsuneo T Nakamoto Yuji Y

EJNMMI research 20210125 1

<h4>Background</h4>[18F]Fluoromisonidazole ([18F]FMISO) is a PET imaging probe widely used for the detection of hypoxia. We previously reported that [18F]FMISO is metabolized to the glutathione conjugate of the reduced form in hypoxic cells. In addition, we found that the [18F]FMISO uptake level varied depending on the cellular glutathione conjugation and excretion ability such as enzyme activity of glutathione-S-transferase and expression levels of mu ...[more]

PMID: 33492449

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