A metabolomics approach for the early diagnosis of brain metastasis
Alex M. Dickens, Timothy D. W. Claridge, James R. Larkin, Alastair Hamiliton, Emma O'Brien, Daniel C. Anthony, Nicola R. Sibson
Poster at NCRI Cancer Conference, Liverpool, UK (2011)
Background: 20-40% of all cancer patients will develop brain metastasis. Current MRI diagnostic techniques only detect late stage metastases, since they rely on blood-brain-barrier permeability to allow gadolinium contrast enhancement. We have previously shown that it is possible to discriminate between different inflammatory lesions in the CNS in rats through analysis of urine samples using metabolmics. The aim of this study was to determine whether the presence of brain metastases could be detected, in an in vivo model, using NMR analysis of biofluids.
Method: Metastatic murine mammary carcinoma (4T1-GFP) cells were injected into the brain, heart or tail vein of female BALB/c mice. Plasma and urine were collected at day 10 from all the animals. Samples were also collected at days 5, 28 and 35 in animals injected intracerebrally. Saline-injected and naïve animals served as controls. Samples were analysed using 1H-NMR spectroscopy, and statistical pattern recognition was applied to identify differences between the spectra.
Results: Significant separations were found between animals injected intracerebrally with 4T1-GFP cells and both control groups for the intracerebral injections (q2 = 0.71 for 4T1 vs. PBS). Significant separations were also found between each of the time-points following intracerebral injection of 4T1 cells, and also between groups of animals with different tumour burdens in the brain and periphery, owing to route of tumour cell injection (q2 = 0.86 for intracerebral vs. intracardiac injections, and 0.71 for intracerebral vs. intravenous injections).
Conclusions: Our data indicate that animals with brain metastases can be identified using a biofluid-metabolomics approach. This analysis appears to be sensitive to different tumour burdens in the brain, and could differentiate between animals with systemic and brain metastases. Studies with different tumour cell lines are in progress. This may identify a set of biomarkers for the diagnosis of brain metastasis at an earlier time point than is currently possible.
References: Griffin, J.L., et al. Study of cytokine induced neuropathology by high resolution proton NMR spectroscopy of rat urine. FEBS Letters 568, 49-54 (2004). DOI: 10.1016/j.febslet.2004.04.096