ABSTRACT:The objective of present study was to offer insights into the metabolic responses of hepatocellular carcinoma (HCC) to surgical resection and the metabolic signatures latent in early HCC recurrence (one year after operation). Urinary metabolic profiling employing gas chromatography time-of-flight mass spectrometry (GC-TOF MS) was utilized to investigate the complex physiopathologic regulations in HCC after operational intervention. It was revealed that an intricate series of metabolic regulations including energy metabolism, amino acid metabolism, nucleoside metabolism, tricarboxylic acid (TCA) cycle, gut floral metabolism, etc., principally leading to the direction of biomass synthesis, could be observed after tumor surgical removal. Moreover, metabolic differences between recurrent and nonrecurrent patients had emerged 7 days after initial operation. The metabolic signatures of HCC recurrence principally comprised notable up-regulations of lactate excretion, succinate production, purine and pyrimidine nucleosides turnover, glycine, serine and threonine metabolism, aromatic amino acid turnover, cysteine and methionine metabolism, and glyoxylate metabolism, similar to metabolic behaviors of HCC burden. Sixteen metabolites were found to be significantly increased in the recurrent patients compared with those in nonrecurrent patients and healthy controls. Five metabolites (ethanolamine, lactic acid, acotinic acid, phenylalanine and ribose) were further defined; they were favorable to the prediction of early recurrence. KEYWORDS: urine, metabolomics, hepatocellular carcinoma, GC−MS, surgery, metabolic signature, recurrence ■ INTRODUCTION Hepatocellular carcinoma (HCC) is one of the most prevalent neoplasms worldwide especially in the eastern Asia and subSaharan Africa.1 It is characterized by a high mortality and a low 5-year survival rate, primarily due to high recurrence and metastasis rates.2 Prevention of both recurrence and metastasis could improve the efficacy of current treatment modalities and enhance survival rates. TNM staging of HCC, estimated using tumor size, tumor multiplicity, vessel invasion, lymph node metastasis, and distant metastasis is viewed as the most reliable indicator for early recurrence. However, TNM staging is often insufficient, even when combined with other established indicators.3 Therefore, discovery of biomarkers more reliably indicating the risk of recurrence is of the utmost importance.Metabolomics, as an emerging omics technique, pursues the comprehensive projection of dynamic multiple metabolic responses to biological disturbances or gene manipulations in living systems. 4,5 Hence, metabolomic approach has been broadly employed for intensive investigations of metabolic abnormalities in HCC and the potential biomarker discovery, besides the increasingly important roles in prognosis of cancer relapse and metastasis. 6−15 Taurocholic acid, lysophosphatidylcholine 22:5 and lysophosphoethanolamine were discovered as marker metabolites for different stages of hepatocarcinoge...