Detecting retinoic acid-induced biochemical alterations in squamous cell carcinoma using intrinsic fluorescence spectroscopy.

Abstract

Intrinsic fluorescence spectroscopy offers a new method for diagnosing head and neck cancers. By establishing a unique spectral fingerprint for benign tissue, one can readily identify subtle changes in tissue based on altered spectral patterns. The authors applied this technology to a multicellular tumor spheroid (MTS) model and obtained baseline spectral data. A cohort of MTS was treated with the chemopreventive agent retinoic acid (RA) to determine its effect on tumor cells. Excitation and emission spectroscopy were performed on the samples. Spectroscopic scans demonstrated consistently that RA-treated MTS exhibit a decrease in the peak associated with reduced nicotinamide-adenine dinucleotide (NADH) and an increase in the peaks associated with flavins, tryptophan, and cytokeratins when compared to controls. These findings are suggestive of alterations in cellular electron transport, an increase in proteins incorporating tryptophan, and a decrease in adenosine triphosphate (ATP) in the RA-treated cells. A discussion of the potential clinical applications of intrinsic fluorescence spectroscopy is included.