Raman spectroscopy for accurately characterizing biomolecular changes in androgen‐independent prostate cancer cells

Abstract

Metastatic prostate cancer resistant to hormonal manipulation is considered the advanced stage of the disease and leads to most cancer-related mortality. With new research focusing on modulating cancer growth, it is essential to understand the biochemical changes in cells that can then be exploited for drug discovery and for improving responsiveness to treatment. Raman spectroscopy has a high chemical specificity and can be used to detect and quantify molecular changes at the cellular level. Collection of large data sets generated from biological samples can be employed to form discriminatory algorithms for detection of subtle and early changes in cancer cells. The present study describes Raman finger printing of normal and metastatic hormone-resistant prostate cancer cells including analyses with principal component analysis and linear discrimination. Amino acid-specific signals were identified, especially loss of arginine band. Androgen-resistant prostate cancer cells presented a higher content of phenylalanine, tyrosine, DNA and Amide III in comparison to PNT2 cells, which possessed greater amounts of L-arginine and had a B conformation of DNA. The analysis utilized in this study could reliably differentiate the 2 cell lines (sensitivity 95%; specificity 88%).

Using the Method of “Optical Biopsy” of Prostatic Tissue to Diagnose Prostate Cancer

“…Since tumor development is accompanied by structural and biochemical modifications of the tissue, by registering these changes, Raman spectroscopy makes possible identification of various morphological forms of PC, as well as concurrent hyperplastic or preneoplastic processes. Numerous studies have proven this method of examining the prostatic tissue [ 10 , 11 , 12 , 13 , 14 ] and blood plasma [ 15 ] potentially viable in diagnosing prostate cancer.…”

“…In other scientific works [ 11 , 12 , 13 , 14 ], the possibilities of Raman spectroscopy with excitation at different wavelengths of laser radiation (633, 785, and 1064 nm) were investigated. In this works, the differences in the average spectra of cancer and control groups were analyzed, or the method of principal components was applied.…”

The Impact of Preprocessing Methods for a Successful Prostate Cell Lines Discrimination Using Partial Least Squares Regression and Discriminant Analysis Based on Fourier Transform Infrared Imaging

“…Methods like Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy are well established in biomedical applications [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ] and offer a label-free biochemical snapshot of various biological processes. They have been successfully applied to prostate cell line discrimination in the past [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. The biochemical sensitivity of IR spectroscopy usually needs to be leveraged by the application of advanced multivariate algorithms, which opens up a whole field of optimization of such approaches [ 24 , 25 , 26 , 27 ].…”

Imaging the invisible—Bioorthogonal Raman probes for imaging of cells and tissues

“…In combination with microscopy-based imaging, a spatial resolution between 300 and 500 nm can be achieved, which allows for subcellular resolution, for example, imaging the nucleus and lipid droplets inside a single cell [5,6]. Especially in single cell research, Raman spectroscopy has proven itself a valuable tool in many applications, for example, for an identification of eukaryotic and prokaryotic cells, for the characterization of drug-cell interactions or for the differentiation of apoptotic and necrotic cells [7][8][9][10][11][12]. Still most Raman related studies are performed on limited numbers of cells, that is, in the order of 100 cells, which does not account for the natural heterogeneity observed within 2D cell culture models or tissues.…”

“…A new class of small Ramanactive labels has emerged, frequently summarized under the name bioorthogonal labels. The modifications can be based on stable isotope labeling by only exchanging single atoms, for example, hydrogen ( 1 H) with deuterium ( 2 H) or 12 C with 13 C, or the addition of a single molecular group with a large Raman scattering cross section, for example, nitrile, azide or alkyne groups. Both approaches lead to specific vibrations in the wavenumber range of a Raman spectrum, the so-called silent region that does not overlap with other cellular Raman contributions also providing high multiplexing capabilities [22,23].…”