Magnetic Resonance Spectroscopy Detectable Metabolomic Fingerprint of Response to Antineoplastic Treatment

Abstract

Targeted therapeutic approaches are increasingly being implemented in the clinic, but early detection of response frequently presents a challenge as many new therapies lead to inhibition of tumor growth rather than tumor shrinkage. Development of novel non-invasive methods to monitor response to treatment is therefore needed. Magnetic resonance spectroscopy (MRS) and magnetic resonance spectroscopic imaging are non-invasive imaging methods that can be employed to monitor metabolism, and previous studies indicate that these methods can be useful for monitoring the metabolic consequences of treatment that are associated with early drug target modulation. However, single-metabolite biomarkers are often not specific to a particular therapy. Here we used an unbiased 1H MRS-based metabolomics approach to investigate the overall metabolic consequences of treatment with the phosphoinositide 3-kinase inhibitor LY294002 and the heat shock protein 90 inhibitor 17AAG in prostate and breast cancer cell lines. LY294002 treatment resulted in decreased intracellular lactate, alanine fumarate, phosphocholine and glutathione. Following 17AAG treatment, decreased intracellular lactate, alanine, fumarate and glutamine were also observed but phosphocholine accumulated in every case. Furthermore, citrate, which is typically observed in normal prostate tissue but not in tumors, increased following 17AAG treatment in prostate cells. This approach is likely to provide further information about the complex interactions between signaling and metabolic pathways. It also highlights the potential of MRS-based metabolomics to identify metabolic signatures that can specifically inform on molecular drug action.

MR-detectable metabolic consequences of mitogen-activated protein kinase kinase (MEK) inhibition

“…Cells were incubated with U0126 (LC Laboratories, Woburn, MA, USA) at doses of 50 μ m for PC3 and 25 μ m for MCF‐7 and A375 cells. All treatments were performed over 48 h with matching DMSO solvent controls (1: 1000 in the culture medium), and U0126 was replenished every 24 h. Treatment doses were determined as described previously using the WST‐1 cell proliferation assay (Roche, Indianapolis, IN, USA), and doses were selected such that they induced a 50% decrease in cell viability after 48 h of treatment. In all cases, inhibition of the target at the selected drug dose was confirmed by probing for phosphorylated extracellular signal‐regulated kinase (p‐ERK) levels using Western blotting (see below).…”

Near infrared fluorescent imaging of choline kinase alpha expression and inhibition in breast tumors

“…A limitation of this approach is that metabolite levels are also affected by the contributions of phospholipases, organic cation transporters, and sphingomyelinases [3, 24, 25]. Moreover, cell death can lead to deceptive decreases in tCho in MR spectra, requiring the measurement of secondary biomarkers [26, 27]. 18 F and 11 C choline PET tracers are useful for identifying ChoK inhibition [28], but choline tracer accumulation can be affected by choline transport inhibitors [29, 30] which have known toxicities [31].…”

Comparison of Metabolic Profiles of Normal and Cancer Cells in Response to Cytotoxic Agents

“…That glutamine was increased in response to cytotoxic agents is consistent to previous several studies. 31,32 Glutaminolysis is induced by HIF-1 or MYC, which often up-regulated in cancer cell lines. 15,33 After treating cytotoxic agents, glutamine greatly increased in all three treated groups in A549 cells, but decreased in all three treated groups in MRC5.…”