FTIR microspectroscopy and multivariate analysis facilitate identification of dynamic changes in epithelial‐to‐mesenchymal transition induced by TGF‐β in prostate cancer cells

Abstract

The standard diagnosis of prostate cancer is accomplished by the identification of cytomorphological deviations in biopsied tissues while immunohistochemistry is used to resolve the equivocal cases. Accumulating evidence favors the concept that epithelial‐to‐mesenchymal transition (EMT) is a stochastic process composed of multiple intermediate states instead of a single binary switch. Despite its significant role in promoting cancer aggressiveness, the current tissue‐based risk stratification tools do not include any of the EMT phenotypes as a metric. As a proof‐of‐concept, the present study analyzes the temporal progression of EMT in transforming growth factor‐beta (TGF‐β) treated PC3 cells encompassing multifarious characteristics such as morphology, migration and invasion, gene expression, biochemical fingerprint, and metabolic activity. Our multimodal approach reinstates EMT plasticity in TGF‐β treated PC3 cells. Further, it highlights that mesenchymal transition is accompanied by discernible changes in cellular morphometry and molecular signatures particularly in the range of 1800–1600 cm−1 and 3100–2800 cm−1 of Fourier‐transformed infrared (FTIR) spectra signifying Amide III and lipid, respectively. Investigation of attenuated total reflectance (ATR)‐FTIR spectra of extracted lipids from PC3 cell populations undergoing EMT identifies changes in stretching vibration at FTIR peaks at 2852, 2870, 2920, 2931, 2954, and 3010 cm−1 characteristics of fatty acids and cholesterol. Chemometric analysis of these spectra indicates that the level of unsaturation and acyl chain length of fatty acid coregister with differential epithelial/mesenchymal states of TGF‐β treated PC3 cells. Observed changes in lipids also correlate with cellular nicotinamide adenine dinucleotide hydrogen (NADH) and flavin adenine dinucleotide dihydrogen (FADH2) levels and mitochondrial oxygen consumption rate. In summary, our study establishes that morphological and phenotypic traits of epithelial/mesenchymal variants of PC3 cells concur with their respective biochemical and metabolic properties. It also underscores that spectroscopic histopathology has a definitive potential to refine the diagnosis of prostate cancer reckoning its molecular and biochemical heterogeneities.