Dichloroacetate induced intracellular acidification in glioblastoma: in vivo detection using AACID-CEST MRI at 9.4 Tesla
| Autor: | Susan O. Meakin, Alex X. Li, Mohammed Albatany, Robert Bartha |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Cancer Research Pyruvate dehydrogenase kinase Intracellular pH Contrast Media Pharmacology Brain cancer 03 medical and health sciences chemistry.chemical_compound Mice 0302 clinical medicine In vivo Cell Line Tumor medicine Biomarkers Tumor Animals chemistry.chemical_classification Glioblastoma multiforme (GBM) Dichloroacetic Acid Brain Neoplasms pH Lonidamine Transporter Hydrogen-Ion Concentration medicine.disease Magnetic Resonance Imaging 030104 developmental biology Enzyme Neurology Oncology Biochemistry chemistry Apoptosis 030220 oncology & carcinogenesis Sodium dichloroacetate (DCA) Neurology (clinical) Glioblastoma CEST MRI |
| Zdroj: | Medical Biophysics Publications |
| Popis: | Intracellular pH (pHi) plays an important role in the maintenance of normal cell function, and is maintained within a narrow range by the activity of transporters located at the plasma membrane. Modulation of tumor pHi may influence proliferation, apoptosis, chemotherapy resistance, and thermosensitivity. Chemical exchange saturation transfer (CEST) is a novel MRI contrast mechanism that is dependent on cellular pH. Amine and amide concentration-independent detection (AACID) is a recently developed CEST contrast method that is intracellular pH (pHi) weighted. Dichloroacetate (DCA) can alter tumor pHi by inhibiting the enzyme pyruvate dehydrogenase kinase causing reduced lactate (increasing pHi), or by decreasing the expression of monocarboxylate transporters and vacuolar ATPase leading to reduced pHi. Since the net in vivo effect of DCA on pHi is difficult to predict, the purpose of this study was to quantify the magnitude of acute pHi change in glioblastoma after a single DCA injection using AACID CEST MRI. Using a 9.4T MRI scanner, CEST spectra were acquired in six mice approximately 14 days after implanting 105 U87 human glioblastoma multiforme (GBM) cells in the brain, before and after intravenous injection of DCA (dose: 200 mg/kg). Three additional mice received only phosphate buffered saline (PBS) injection and were studied as controls. Repeated measures t test was used to compare AACID changes in tumor and contralateral tissue regions of interest. One hour after DCA injection there was a significant increase in tumor AACID level by 0.04 ± 0.01 corresponding to a 0.16 decrease in pHi, and no change in AACID in contralateral tissue. Inspection of AACID maps following PBS injection showed no differences. The use of DCA to induce a tumor specific pH change detectable by AACID CEST MRI is consistent with previous studies that have shown similar effects for lonidamine and topiramate. This study demonstrates that a single dose of DCA can be used as a pharmacological challenge to induced rapid tumor intracellular acidification. |
| Databáze: | OpenAIRE |
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