The Volatilomic Footprints of Human HGC-27 and CLS-145 Gastric Cancer Cell Lines.

Chris A Mayhew,Axel Mündlein,Linda Mezmale,Andreas Leiherer,Paweł Mochalski,Marcis Leja,Heinz Drexel,Christine Heinzle,Ilze Kikuste,Daria Ślefarska

doi:10.3389/fmolb.2020.607904

Abstract

The presence of certain volatile biomarkers in the breath of patients with gastric cancer has been reported by several studies; however, the origin of these compounds remains controversial. In vitro studies, involving gastric cancer cells may address this problem and aid in revealing the biochemical pathways underlying the production and metabolism of gastric cancer volatile indicators. Gas chromatography with mass spectrometric detection, coupled with headspace needle trap extraction as the pre-concentration technique, has been applied to map the volatilomic footprints of human HGC-27 and CLS-145 gastric cancer cell lines and normal Human Stomach Epithelial Cells (HSEC). In total, 27 volatile compounds are found to be associated with metabolism occurring in HGC-27, CLS-145, and HSEC. Amongst these, the headspace concentrations of 12 volatiles were found to be reduced compared to those above just the cultivating medium, namely there was an observed uptake of eight aldehydes (2-methylpropanal, 2-methyl-2-propenal, 2-methylbutanal, 3-methylbutanal, hexanal, heptanal, nonanal, and benzaldehyde), three heterocyclic compounds (2-methyl-furan, 2-ethyl-furan, and 2-pentyl-furan), and one sulfur-containing compound (dimethyl disulphide). For the other 15 volatiles, the headspace concentrations above the healthy and cancerous cells were found to be higher than those found above the cultivating medium, namely the cells were found to release three esters (ethyl acetate, ethyl propanoate, and ethyl 2-methylbutyrate), seven ketones (2-pentanone, 2-heptanone, 2-nonanone, 2-undecanone, 2-tridecanone, 2-pentadecanone, and 2-heptadecanone), three alcohols (2-methyl-1-butanol, 3-methyl-1-butanol, and 2-ethyl-1-hexanol), one aromatic compound (toluene), and one sulfur containing compound [2-methyl-5-(methylthio) furan]. In comparison to HSEC, HGC-27 cancer cell lines were found to have significantly altered metabolism, manifested by an increased production of methyl ketones containing an odd number of carbons. Amongst these species, three volatiles were found exclusively to be produced by this cell line, namely 2-undecanone, 2-tridecanone, and 2-heptadecanone. Another interesting feature of the HGC-27 footprint is the lowered level of alcohols and esters. The CLS-145 cells exhibited less pronounced changes in their volatilomic pattern compared to HSEC. Their footprint was characterized by the upregulated production of esters and 2-ethyl-hexanol and downregulated production of other alcohols. We have therefore demonstrated that it is possible to differentiate between cancerous and healthy gastric cells using biochemical volatile signatures.

Highlights

There is growing interest in the human volatilome as a powerful tool capable of providing novel biomarkers for medical diagnosis and therapy monitoring (Beauchamp et al, 2020)
A classification model based on principal component analysis (PCA) and employing gas chromatography mass spectrometry (GC-MS) abundancies of these volatiles provided 90% accuracy, 93% sensitivity, and 87% specificity
We focus on the volatilomic footprints of human HGC-27 and CLS-145 gastric cancer cell lines and normal Human Stomach Epithelial Cells (HSEC)

Summary

Introduction

There is growing interest in the human volatilome as a powerful tool capable of providing novel biomarkers for medical diagnosis and therapy monitoring (Beauchamp et al, 2020). The analysis of biochemical volatile footprints in breath, skin emanations, and in other bodily fluids, such as urine, saliva, or sweat, provides a unique opportunity to monitor microbiota activity, individuals’ exposure to environmental toxins, or for use in screening for various diseases, including cancer (Haick et al, 2014; Broza et al, 2015; del Rio et al, 2015; Beauchamp et al, 2020). This volatilomic approach suffers, from a number of limitations, which constrict its application within a clinical setting. The main unresolved issue here is the often poor biochemical understanding of the origin, behavior and metabolic fate of volatile biomarkers in the human organism

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