Glycoprofiling Of Salivary Glycoproteins From Healthy People And Liver Cancer Patients

Purpose:Glycosylation is an important component for a number of biological processes and is the most abundant and complicated of the known post-translational modifications found on proteins. The occurrences and developments of liver cancer are accompanied by changes in structures and functions of glycoproteins. Saliva, as a body fluid, is a rich source of N-and O-linked glycoproteins. Saliva testing, a simple and non-invasive alternative to serum, has drawn widely attention of researchers to find saliva biomarker for monitoring physiological and pathological conditions in humans, as well as for early diagnosis of diseases. At present, researches on the relationship between saliva and disease mainly focus in the changes of salivary proteins abundance and kinds, and glycoprofiling of the human salivary associated with the processes of cancer are very little involved. Therefore this study analyzed human salivary glycoproteins by high-throughput and sensitivity lectin microarrys, then identifyed and compared the glycopatterns of healthy people associated with different ages groups and different gender. And we expect to find specific saliva biomarkers from liver cancer patients for early diagnosis of liver cancer.Method:First, saliva samples were collected from healthy people of three different age groups and liver cancer patients; then extracted and purifyed salivary proteins, labled them with Cy3 fluorescent dye and then incubated with lectin microarray. According to the principle of lectin to glycan binding affinity, we analyzed the salivary glycoproteins differences of healthy people associated with different gender in different age groups, and screened differential expression glycopatterns between liver cancer patients and healthy people.Results:1. By analyzing healthy people saliva, we found that kinds of glycoproteins make up a major and important part of human salivary proteome, including:(1) There were little glycopattern expression differences between male and female children, Galactose was higher in male children, while GalNAc,β-1,4 GlcNAc and LacNAcwere higher in female children; (2) The differences of salivary glycan structures between healthy male and female adults were significantly, terminal GalNAc,Gal,β-1,4GlcNAc,LacNAc andα-1,6Man structures were more expressed in male adults; while GlcNAc,αGalNAc,αGal,GalNAcα-Ser/Thr(Tn),Sia2-6Gαlβ1-4Glc(NAc), Fucα-1,2and core Fucα-1,6 structures were more expressed in female adults; (3) Salivary glycoproteins glycan structures were more abundant in healthy older men than in women. In the older men saliva, Gal,αGalNAc,α-1,3 andα-1,6 linked mannose,core Fucα-1,6 and GalNAcα-Ser/Thr(Tn-antigen) structures were induced, whereas Fucα-1,3,terminal GalNAc andsialyl-Lewisx(sLex)structures were higher in older women salivary glycoproteins.2. Seven salivary samples of liver cancer patients(older men) and healthy people in the same age group and gender were initially analyzed by lectin microarrays. The results were as follows:in liver cancer patients, Gal,GalNAc bisecting GlcNAc,biantennary N-glycans,Fucα-1,3,core Fucα-1,6,sialyl-Lewisx(sLex) and Siaα-2,6 glycan structures which specificitily recognized by RCA120,WFA,PHA-E,AAL LTL and SNA were increased; whereasαGalNAc,αGal,β1-4GlcNAc,terminal GalNAc,αMan,GalNAcα-Ser/Thr(Tn),Siaα-2,3and mμltivalent Sia glycan structures that recognized by BS-I,PTL-Ⅱ, DSA,SBA,ConA,GNA, GSL-ⅠVVA,MAL-Ⅱand WGA were reduced in liver cancer patients.Conclusion:1. Saliva is a rich source of N-and O-linked glycoproteins. With the growth of age, salivary glycoproteins of healthy people is increasing, and glycopattern expression of different gender in the same age group is differed. The salivary glycan structures differences between healthy male and female adults were the most significantly.2. Gal,GalNAc,bisecting GlcNAc,biantennary N-glycans,Fucα-1,3,core Fuca-1,6,sialyl-Lewisx(sLex) and Siaα-2,6 glycan structures are higher in liver cancer patients, suggesting that these salivary glycopatterns may be used as a potential diagnostic biomarker of liver cancer.