Intrinsic fluorescence biomarkers in cells treated with chemopreventive drugs

摘要

Non-invasive monitoring of cellular metabolism offers promising insights into areas ranging from biomarkers for drugactivity to cancer diagnosis. Fluorescence spectroscopy can be utilized in order to exploit endogenous fluorophores,typically metabolic co-factors nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), andestimate the redox status of the sample. Fluorescence spectroscopy was applied to follow metabolic changes inepithelial ovarian cells as well as bladder epithelial cancer cells during treatment with a chemopreventive drug thatinitiates cellular quiescence. Fluorescence signals consistent with NADH, FAD, and tryptophan were measured tomonitor cellular activity, redox status, and protein content. Cells were treated with varying concentrations of N-4-(hydroxyphenyl) retinamide (4-HPR) and measured in a stable environment with a sensitive fluorescence spectrometer.A subset of measurements was completed on a low concentration of cells to demonstrate feasibility for medicalapplication such as in bladder or ovary washes. Results suggest that all of the cells responded with similar dosedependence but started at different estimated redox ratio baseline levels correlating with cell cycle, growth inhibition,and apoptosis assays. NADH and tryptophan related fluorescence changed significantly while FAD relatedfluorescence remained unaltered. Fluorescence data collected from approximately 1000 - 2000 cells, comparable to abladder or ovary wash, was measurable and useful for future experiments. This study suggests that future intrinsicbiomarker measurements may need to be most sensitive to changes in NADH and tryptophan related fluorescence whileusing FAD related fluorescence to help estimate the baseline redox ratio and predict response to chemopreventiveagents.