Urinary Volatomic Expression Pattern: Paving the Way for Identification of Potential Candidate Biosignatures for Lung Cancer

Abstract

The urinary volatomic profiling of Indian cohorts composed of 28 lung cancer (LC) patients and 27 healthy subjects (control group, CTRL) was established using headspace solid phase microextraction technique combined with gas chromatography mass spectrometry methodology as a powerful approach to identify urinary volatile organic metabolites (uVOMs) to discriminate among LC patients from CTRL. Overall, 147 VOMs of several chemistries were identified in the intervention groups—including naphthalene derivatives, phenols, and organosulphurs—augmented in the LC group. In contrast, benzene and terpenic derivatives were found to be more prevalent in the CTRL group. The volatomic data obtained were processed using advanced statistical analysis, namely partial least square discriminative analysis (PLS-DA), support vector machine (SVM), random forest (RF), and multilayer perceptron (MLP) methods. This resulted in the identification of nine uVOMs with a higher potential to discriminate LC patients from CTRL subjects. These were furan, o-cymene, furfural, linalool oxide, viridiflorene, 2-bromo-phenol, tricyclazole, 4-methyl-phenol, and 1-(4-hydroxy-3,5-di-tert-butylphenyl)-2-methyl-3-morpholinopropan-1-one. The metabolic pathway analysis of the data obtained identified several altered biochemical pathways in LC mainly affecting glycolysis/gluconeogenesis, pyruvate metabolism, and fatty acid biosynthesis. Moreover, acetate and octanoic, decanoic, and dodecanoic fatty acids were identified as the key metabolites responsible for such deregulation. Furthermore, studies involving larger cohorts of LC patients would allow us to consolidate the data obtained and challenge the potential of the uVOMs as candidate biomarkers for LC.

Effect of chemotherapy on urinary volatile biomarkers for lung cancer by HS‐SPME‐GC‐MS and chemometrics

“…To our knowledge, this is the first time that this potential biomarker has been identified by comparing lung cancer patients with other cancer patients. In most previous studies, lung cancer patients were compared with healthy people 6,7,10–12,14,21,22 . This ketone, as previously discussed, could be a final product of the increased rate of fatty acid oxidation and protein hypermetabolism that occurs specifically during cancer development 10 .…”

“…In addition to its noninvasive nature and availability in large volumes, the advantage of analyzing VOCs in urine is that the kidneys concentrate the analytes before excreting them, so their detection can be greater than in other biological fluids, such as exhaled breath and blood 10,16 . Therefore, the analysis of the volatile urine profile could be a feasible detection method in many parts of the world, being also much cheaper than computed tomography and without exposing the patient to the risks associated with the radiation used 12,13 …”

“…Once formed, VOCs enter the bloodstream and are transported to the lungs, which is why exhaled breath is the most studied sample type 8–10 . In addition, VOCs are metabolized in the liver and excreted in urine, which is why this type of sample is being increasingly studied, also due to its ease of collection and the greater volume obtained 8,11,12 …”

“…[8][9][10] In addition, VOCs are metabolized in the liver and excreted in urine, which is why this type of sample is being increasingly studied, also due to its ease of collection and the greater volume obtained. 8,11,12 These two sample types have already been studied in lung cancer detection by dogs. These animals have a very sensitive olfactory system with low perception thresholds.…”

Tumors due to chronic exposure to benzene and biomarkers of exposure

“…With this aim, investigations are performed by liquid biopsy on cell-free DNA (cfDNA), all kinds of RNA (cfRNA), and volatile organic metabolites (VOMs). In the institutions where advanced molecular methods are available, the detection of cfDNA EGFR T790M mutation [responsible for resistance to gefitinib/erlotinib treatment in non-small cell lung cancer (NSCLC)] is already routine [67] . VOMs derived from differentiated cell metabolism are under investigation using biofluids (exhaled breath, pleural effusions, blood, urine, etc.)…”