Uptake of [¹⁸F]tetrafluoroborate in MCF-7 Breast Cancer Cells is Induced after Stimulation of the Sodium Iodide Symporter

Author(s): Marc Lehmacher*, Antje Stolzenburg, Samuel Samnick.

Journal Name: Current Cancer Drug Targets

Volume 20 , Issue 2 , 2020

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Abstract:

Background: The human sodium iodide symporter (hNIS) has been the most important target in nuclear medicine regarding thyroid-related diseases. Although hNIS-expression can also be determined in extra-thyroidal tumors, imaging hNIS with positron emission tomography has not been exploited clinically.

Objective: Here, we evaluated the accumulation of the novel hNIS-substrate [18F]tetrafluoroborate ([18F]TFB) in the endogenously hNIS-expressing breast cancer cell line MCF-7 after an improved radiosynthesis and pharmacological stimulation.

Methods: [18F]TFB was prepared under mild reaction conditions (40°C, 25 min) and its uptake properties were investigated in MCF-7 cells pretreated with a combination of all-trans retinoic acid plus methasone-derivatives and compared to the clinically established tracers [131I]iodide and [99mTc]pertechnetate. Specificity of the tracer accumulation was assessed by inhibition experiments using NaBF4, KSO3F, KI and KIO3.

Results: [18F]TFB was obtained with a radiochemical yield of 24.0 ± 6.6 % (n = 17) within 40 min after high pressure liquid chromatography-separation and with 26.8 ± 6.2 % (n = 13) within 45 min after adapting the procedure on a synthesis module using higher starting activities (> 10 GBq). After pharmacological treatment, a 4-fold increase in hNIS-expression on the MCF-7 cell surface was achieved, resulting in a significantly higher [18F]TFB uptake into the cells (up to 58-fold) as compared to control experiments. Inhibition studies using various NIS-substrates confirmed the specificity of [18F]TFB for hNIS.

Conclusion: [18F]TFB was shown to be a promising hNIS-substrate in our model using the human MCF-7 breast cancer cell line mandating in vivo evaluations in xenografted studies and in patients.

Keywords: Sodium iodide symporter (NIS), [18F]tetrafluoroborate, [18F]TFB, breast cancer, MCF-7, PET-imaging.

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Article Details

VOLUME: 20
ISSUE: 2
Year: 2020
Page: [146 - 155]
Pages: 10
DOI: 10.2174/1568009619666191016145602
Price: $65

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