Metabonomics Methods Used To Screen Markers For The Diagnosis And Treatment Of Nasopharyngeal Carcinoma

Objective:Gas chromatography-mass spectrometry based metabolic profiling was used to investigate the differences of serum metabolic patterns between patients with nasopharyngeal carcinoma (NPC) and healthy controls to find tentative diagnostic biomarkers. Based on the findings above, we tried to describe the metabolite changes related to the continuous phases of radiotherapy. It will provide a novel technological platform for the mechanism study of NPC.Methods:1. Patients: 10 newly-diagnosed patients with NPC who match the selection conditions served as NPC group. 10 healthy persons served as control group.2. Sample collection: Serum samples were collected from 10 persons in the control group through venous blood. Serum samples of 10 patients in the NPC group were collected before radiotherapy, at the 1^st, 3^rd, 5^th, 7^th week during the radiotherapy and 3 months after the radiotherapy.3. GC-MS analysis of serum samples: The serum samples were derivatized, and then analyzed with gas chromatography-mass spectrometry (GC-MS). The serum metabolic profiles were obtained. The serum endogenous metabolites were identified.4. Data analysis: PCA (principal component analysis) and PLS-DA (partial least squares-discriminant analysis) were performed for the multivariate statistical analysis. t-test was applied for the univariate statistical analysis.Results:1. 25 serum endogenous metabolites related to NPC were identified by GC-MS anaysis. They were lactate, 2-ketoisocaproic acid, alanine,α-hydroxybutyric acid,β-hydroxybutyric acid, urea, phosphate, leucine, glycerol, isoleucine, proline, serine, threonine, pyroglutamic acid, phenylalanine,α-glycerolphosphoric acid, tyrosine, palmitic acid, linoleic acid, oleic acid, stearic acid, arachidonic acid, monnopalmitin, monostearin and cholesterol.2. PCA and PLS-DA data showed that there were different serum metabolic patterns between newly diagnosed patients with NPC and the control group, but there was no difference before and 3 months after therapy.3. PCA data showed that there were metabolic differences between the control group and the NPC group (both before therapy and 3months after therapy), but there was no difference before therapy and 3months after therapy.4. 25 serum endogenous metabolites were analyzed in both the controlgroup and the NPC group using t-test, of which, 14 endogenous metabolites had significant difference. Compared with the control group, lactate, alanine,α-hydroxybutyric acid,β-hydroxybutyric acid, leucine, isoleucine, proline, serine, threonine, phenylalanine and monnopalmitin increased in the NPC group, and 2-ketoisocaproic acid, linoleic acid and oleic acid decreased.5. Description of the dynamic changes of 14 metabolites during the radiotherapy showed that 8 endogenous metabolites (2-ketoisocaproic acid,α-hydroxybutyric acid,β-hydroxybutyric acid, leucine, isoleucine, threonine, linoleic acid and monnopalmitin) had the trend towards the normal level.Conclusion:1. The different serum metabolic profiles between NPC patients and healthy controls (the increase of lactate, alanine,α-hydroxybutyric acid,β-hydroxybutyric acid, leucine, isoleucine, proline, serine, threonine, phenylalanine and monnopalmitin in NPC patients and the decrease of 2-ketoisocaproic acid, linoleic acid and oleic acid) indicates that a variety of external and endogenous carcinogenic factors involve in and result in the serum metabolic profile of NPC patients.2. Lactate, alanine,α-hydroxybutyric acid,β-hydroxybutyric acid, leucine, isoleucine, proline, serine, threonine, phenylalanine and monostearin may be potential biomarkers for early diagnosis of NPC.3. The dynamic changes of 8 metabolites (2-ketoisocaproic acid,α-hydroxybutyric acid,β-hydroxybutyric acid, leucine, isoleucine, threonine, linoleic acid and monnopalmitin) during the radiotherapy indicates that they may be associated with tumorigenesis of NPC.