Discrimination between the human prostate normal and cancer cell exometabolome by GC-MS

Ana Rita Lima,Rui Henrique,Ana Margarida Araújo,Maria De Lourdes Bastos,Paula Guedes De Pinho,Carmen Jerónimo,Joana Pinto,Márcia Carvalho

doi:10.1038/s41598-018-23847-9

Abstract

Serum prostate-specific antigen (PSA) is currently the most used biomarker in clinical practice for prostate cancer (PCa) detection. However, this biomarker has several drawbacks. In this work, an untargeted gas chromatography-mass spectrometry (GC-MS)-based metabolomic profiling of PCa cells was performed to prove the concept that metabolic alterations might differentiate PCa cell lines from normal prostate cell line. For that, we assessed the differences in volatile organic compounds (VOCs) profile in the extracellular medium (exometabolome) of four PCa cell lines and one normal prostate cell line at two pH values (pH 2 and 7) by GC-MS. Multivariate analysis revealed a panel of volatile metabolites that discriminated cancerous from normal prostate cells. The most altered metabolites included ketones, aldehydes and organic acids. Among these, we highlight pentadecane-2-one and decanoic acid, which were significantly increased in PCa compared to normal cells, and cyclohexanone, 4-methylheptan-2-one, 2-methylpentane-1,3-diol, 4-methylbenzaldehyde, 1-(3,5-dimethylfuran-2-yl)ethanone, methyl benzoate and nonanoic acid, which were significantly decreased in PCa cells. The PCa volatilome was markedly influenced by the VOCs extraction pH, though the discriminant capability was similar. Overall, our data suggest that VOCs monitoring has the potential to be used as a PCa screening methodology.

Highlights

Double of the total financial costs associated with prostate cancer (PCa) management[14]
A multivariate analysis (MVA) approach was applied to evaluate the ability of volatilome to discriminate the different cell lines used in this study
The sensitivity and specificity of the discriminative sets of metabolites obtained for each pair were calculated and the results reveal that the discriminant sets have a sensitivity and specificity of 100% or very close to this value for discriminating the PCa cell lines from the normal prostate cell line (Supplementary Table 3)

Summary

Introduction

Double of the total financial costs associated with PCa management[14]. Due to these limitations, the use of PSA for populational screening has been challenged[15]. We believe that cell lines are the ideal matrix for hypothesis generation and to unveil unchanged metabolic signature originated directly from cells, metabolic alterations that do not appear in studies using animal models or human subjects, due to sample biological complexity, may be revealed[19,20,21] Notwithstanding, this in vitro model presents some limitations, the fact that cultured cells fail to reproduce the complex cell–cell and cell–matrix interactions in the tumour microenvironment and these interactions are very important for metabolic alterations occurring with tumor progression[20,22]. Alterations in VOCs profile may be related to modifications in gene activation, gene expression, proteins and activity of enzymes involved in metabolic pathways[26,27]

Objectives

Methods

Results

Discussion

Conclusion