Segregation of human prostate tissues classified high-risk (UK) versus low-risk (India) for adenocarcinoma using Fourier-transform infrared or Raman microspectroscopy coupled with discriminant analysis

Vibrational spectroscopy techniques can be applied to identify a susceptibility-to-adenocarcinoma biochemical signature. A sevenfold difference in incidence of prostate adenocarcinoma (CaP) remains apparent amongst populations of low- (e.g. India) compared with high-risk (e.g. UK) regions, with migrant studies implicating environmental and/or lifestyle/dietary causative factors. This study set out to determine the biospectroscopy-derived spectral differences between risk-associated cohorts to CaP. Benign prostate tissues were obtained using transurethral resection from high-risk (n = 11, UK) and low-risk (n = 14, India) cohorts. Samples were analysed using attenuated total reflection Fourier-transform infrared (FTIR) spectroscopy, FTIR microspectroscopy and Raman microspectroscopy. Spectra were subsequently processed within the biochemical cell region (1,800⁻¹–500 cm^–1) employing principal component analysis (PCA) and linear discriminant analysis (LDA) to determine whether wavenumber–absorbance/intensity relationships might reveal biochemical differences associated with region-specific susceptibility to CaP. PCA-LDA scores and corresponding cluster vector plots identified pivotal segregating biomarkers as 1,582 cm⁻¹ (Amide I/II trough); 1,551 cm⁻¹ (Amide II); 1,667 cm⁻¹ (Amide I); 1,080 cm⁻¹ (DNA/RNA); 1,541 cm⁻¹ (Amide II); 1,468 cm⁻¹ (protein); 1,232 cm⁻¹ (DNA); 1,003 cm⁻¹ (phenylalanine); 1,632 cm⁻¹ [right-hand side (RHS) Amide I] for glandular epithelium (P < 0.0001) and 1,663 cm⁻¹ (Amide I); 1,624 cm⁻¹ (RHS Amide I); 1,126 cm⁻¹ (RNA); 1,761, 1,782, 1,497 cm⁻¹ (RHS Amide II); 1,003 cm⁻¹ (phenylalanine); and 1,624 cm⁻¹ (RHS Amide I) for adjacent stroma (P < 0.0001). Primarily protein secondary structure variations were biomolecular markers responsible for cohort segregation with DNA alterations exclusively located in the glandular epithelial layers. These biochemical differences may lend vital insights into the aetiology of CaP.