Characterization of Salivary and Plasma Metabolites as Biomarkers for HCC: A Pilot Study

SIMPLE SUMMARY: Hepatocellular carcinoma is diagnosed using ultrasound and blood-biomarker AFP, which can miss up to 40% of diagnoses, delaying the treatment of these patients. The aim of our study was to identify metabolites that are associated with HCC in blood and saliva, and compare the metabolic profiles of these two biofluids. Malonic acid was the only metabolite that was correlated in paired blood and saliva samples, and it was also found to be associated with HCC in saliva. In total, 6 metabolites in saliva and 10 different metabolites in plasma were found to be associated with HCC. The ‘Citric Acid Cycle’ pathway was deregulated in both the blood and saliva of patients with HCC. This suggests that plasma and saliva offer unique sources of metabolite biomarkers, but these metabolites converge on a common pathway in cell metabolism. ABSTRACT: (1) Background: The incidence of hepatocellular carcinoma (HCC) is rising, and current screening methods lack sensitivity. This study aimed to identify distinct and overlapping metabolites in saliva and plasma that are significantly associated with HCC. (2) Methods: Saliva samples were collected from 42 individuals (HCC = 16, cirrhosis = 12, healthy = 14), with plasma samples from 22 (HCC = 14, cirrhosis = 2, healthy = 6). We performed untargeted mass spectrometry on blood and plasma, tested metabolites for associations with HCC or cirrhosis using a logistic regression, and identified enriched pathways with Metaboanalyst. Pearson’s correlation was employed to test for correlations between salivary and plasma metabolites. (3) Results: Six salivary metabolites (1-hexadecanol, isooctanol, malonic acid, N-acetyl-valine, octadecanol, and succinic acid) and ten plasma metabolites (glycine, 3-(4-hydroxyphenyl)propionic acid, aconitic acid, isocitric acid, tagatose, cellobiose, fucose, glyceric acid, isocitric acid, isothreonic acid, and phenylacetic acid) were associated with HCC. Malonic acid was correlated between the paired saliva and plasma samples. Pathway analysis highlighted deregulation of the ‘The Citric Acid Cycle’ in both biospecimens. (4) Conclusions: Our study suggests that salivary and plasma metabolites may serve as independent sources for HCC detection. Despite the lack of correlation between individual metabolites, they converge on ‘The Citric Acid Cycle’ pathway, implicated in HCC pathogenesis.