abstract
The analysis of volatile organic compounds (VOCs) emanating from biological samples appears as one of the most promising approaches in metabolomics for the study of diseases, namely cancer. In fact, it offers advantages, such as non-invasiveness and robustness for high-throughput applications. The purpose of this work was to study the urinary volatile metabolic profile of patients with renal cell carcinoma (RCC) (n=30) and controls (n=37) with the aim of identifying a potential specific urinary volatile pattern as a non-invasive strategy to detect RCC. Moreover, the effect of some confounding factors such as age, gender, smoking habits and body mass index was evaluated as well as the ability of urinary VOCs to discriminate RCC subtypes and stages. A headspace solid-phase microextraction/gas chromatography-mass spectrometry-based method was performed, followed by multivariate data analysis. A variable selection method was applied to reduce the impact of potential redundant and noisy chromatographic variables, and all models were validated by Monte Carlo cross-validation and permutation tests. Regarding the effect of RCC on the urine VOCs composition, a panel of 21 VOCs descriptive of RCC was defined, capable of discriminating RCC patients from controls in principal component analysis. Discriminant VOCs were further individually validated in two independent samples sets (nine RCC patients and 12 controls, seven RCC patients with diabetes mellitus type 2) by univariate statistical analysis. Two VOCs were found consistently and significantly altered between RCC and controls (2-oxopropanal and, according to identification using NIST14, 2,5,8-trimethyl-1,2,3,4-tetrahydronaphthalene-1-ol), strongly suggesting enhanced potential as RCC biomarkers. Gender, smoking habits and body mass index showed negligible and age-only minimal effects on the urinary VOCs, compared to the deviations resultant from the disease. Moreover, in this cohort, the urinary volatilome did not show ability to discriminate RCC stages and histological subtypes. The results validated the value of urinary volatilome for the detection of RCC and advanced with the identification of potential RCC urinary biomarkers.
keywords
VOLATILE ORGANIC-COMPOUNDS; SOLID-PHASE MICROEXTRACTION; CHROMATOGRAPHY-MASS SPECTROMETRY; GAS SENSOR ARRAY; DIABETES-MELLITUS; 1,1,6-TRIMETHYL-1,2-DIHYDRONAPHTHALENE TDN; PATTERN-RECOGNITION; OLFACTORY DETECTION; CANCER BIOMARKERS; BLADDER-CANCER
subject category
Cell Biology; Research & Experimental Medicine
authors
Monteiro, M; Moreira, N; Pinto, J; Pires-Luis, AS; Henrique, R; Jeronimo, C; Bastos, MD; Gil, AM; Carvalho, M; de Pinho, PG
our authors
Ana Maria Pissarra Coelho Gil
Associate Professor with Aggregation
Joana Isabel Monteiro Pinto
Post-doc Fellowship
Márcia de Jesus de Sá Monteiro
PhD Studentacknowledgements
This work received financial support from the European Union (FEDER funds POCI/01/0145/FEDER/007728) and National Funds (FCT/MEC, Fundacao para a Ciencia e Tecnologia and Ministerio da Educacao e Ciencia) under the Partnership Agreement PT2020 UID/MULTI/04378/2013. It was also developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER 007679 (FCT Ref. UID /CTM /50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. M.M. and N.M. acknowledge FCT for their grants, SFRH/BD/80518/2011 and SFRH/BDP/109668/2015, respectively.