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01.10.2010 | Research article | Ausgabe 5/2010 Open Access

Breast Cancer Research 5/2010

17-allyamino-17-demethoxygeldanamycin treatment results in a magnetic resonance spectroscopy-detectable elevation in choline-containing metabolites associated with increased expression of choline transporter SLC44A1 and phospholipase A2

Zeitschrift:
Breast Cancer Research > Ausgabe 5/2010
Autoren:
Alissa H Brandes, Christopher S Ward, Sabrina M Ronen
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​bcr2729) contains supplementary material, which is available to authorized users.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

AHB acquired, analyzed, and interpreted experimental data; contributed to experimental conception and design; and drafted the manuscript. CSW acquired and analyzed microarray data, created the CTP:PC cytidylyltransferase activity assay, and contributed to experimental design. SMR conceived of the study, assisted with interpretation of data, and helped to draft the manuscript. All authors read and approved the final manuscript.

Abstract

Introduction

17-allyamino-17-demethoxygeldanamycin (17-AAG), a small molecule inhibitor of Hsp90, is currently in clinical trials in breast cancer. However, 17-AAG treatment often results in inhibition of tumor growth rather than shrinkage, making detection of response a challenge. Magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) are noninvasive imaging methods than can be used to monitor metabolic biomarkers of drug-target modulation. This study set out to examine the MRS-detectable metabolic consequences of Hsp90 inhibition in a breast cancer model.

Methods

MCF-7 breast cancer cells were investigated, and MRS studies were performed both on live cells and on cell extracts. 31P and 1H MRS were used to determine total cellular metabolite concentrations and 13C MRS was used to probe the metabolism of [1,2-13C]-choline. To explain the MRS metabolic findings, microarray and RT-PCR were used to analyze gene expression, and in vitro activity assays were performed to determine changes in enzymatic activity following 17-AAG treatment.

Results

Treatment of MCF-7 cells with 17-AAG for 48 hours caused a significant increase in intracellular levels of choline (to 266 ± 18% of control, P = 0.05) and phosphocholine (PC; to 181 ± 10% of control, P = 0.001) associated with an increase in expression of choline transporter SLC44A1 and an elevation in the de novo synthesis of PC. We also detected an increase in intracellular levels of glycerophosphocholine (GPC; to 176 ± 38% of control, P = 0.03) associated with an increase in PLA2 expression and activity.

Conclusions

This study determined that in the MCF-7 breast cancer model inhibition of Hsp90 by 17-AAG results in a significant MRS-detectable increase in choline, PC and GPC, which is likely due to an increase in choline transport into the cell and phospholipase activation. 1H MRSI can be used in the clinical setting to detect levels of total choline-containing metabolite (t-Cho, composed of intracellular choline, PC and GPC). As Hsp90 inhibitors enter routine clinical use, t-Cho could thus provide an easily detectable, noninvasive metabolic biomarker of Hsp90 inhibition in breast cancer patients.
Zusatzmaterial
Authors’ original file for figure 1
13058_2010_2716_MOESM1_ESM.pdf
Authors’ original file for figure 2
13058_2010_2716_MOESM2_ESM.pdf
Authors’ original file for figure 3
13058_2010_2716_MOESM3_ESM.pdf
Authors’ original file for figure 4
13058_2010_2716_MOESM4_ESM.pdf
Literatur
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