Novel approach reveals lipid metabolite reduction in nails of breast cancer patients as potential biomarker

ABSTRACT BACKGROUND Molecular adaptations in intracellular and extracellular microenvironment of breast cancer cells promote pro-tumor metabolic reprogramming. Hence, metabolic reprogramming is seen as a crucial factor in various tumor hallmarks including drug resistance, invasiveness and metastasis. Among well-known metabolic features of breast carcinoma including Warburg effects, altered amino acid metabolism, lipid remodeling is considered as key factors in achieving pro-tumor microenvironment. Therefore, a better understanding on molecular aspects of lipid remodeling is highly appreciated that may contribute towards future therapeutics and diagnostics purpose including the need of potential biomarkers. The identification and validation of lipid biomarkers are reported in the literature, but evidence on lipid metabolites as biomarkers in nails of breast cancer patients is completely unexplored. METHODS This study reported a novel and specifically designed vertical tube gel electrophoresis (VTGE) system to assist in the purification of metabolites in the range of (∼100-1000 Da) from nail samples. Fingernail clippings of breast cancer patients (N=10), and healthy subjects (N-12) were used for extraction and purification of metabolites. The VTGE system uses 15% polyacrylamide under non-denaturing and non-reducing conditions that makes eluted metabolites directly compatible with LC-HRMS and other analytical techniques. The characterization of lipid metabolites in nail lysates was done by positive ESI mode of Agilent LC-HRMS platform. RESULTS Data suggest a novel observation that healthy and breast cancer patients show distinct accumulation of lipid metabolites specifically choline-based lipids. This is a first report that suggests that levels of choline, phosphorylcholine and lyso-PC are highly reduced and undetectable in nails of breast cancer patients over healthy subject. Furthermore, the potential use of reduced level of choline, phosphorylcholine and lyso-PC in nails of breast cancer patients is in line with current notion that these lipids are diverted to meet the pro-tumor activities in the tumor microenvironment. CONCLUSION Data strongly provide a proof of concept for the potential use of lipid metabolites including choline, phosphorylcholine and lyso-PC as a set of biomarkers in nails of breast cancer patients. However, the authors propose that validity of these lipid biomarkers may be extended to large population size of breast cancer patients for future applications in early detection, grading, staging, predicting prognosis and therapeutic targeting of breast carcinoma.