Glycoproteomic identification of novel plasma biomarkers for oral cancer

Glycoproteomic identification of novel plasma biomarkers for oral cancer

Oral cancer with high incidence rates is occurring in many countries including in India,Pakistan, Bangladesh, Sri Lanka and Taiwan. Smoking, alcoholism, and betel nut chewingare considered to be the main risk factors for oral cancer. Further, deaths from oral cancerhave increased year by year. Although several oral cancer-associated biomarkers havebeen reported, very few useful biomarkers have been applied for early diagnosis. Therefore,the investigation of oral cancer-specific biomarkers is urgently needed. We previouslyinvestigated N-glycomes of oral cancer cells and patient plasma. We found that both mRNAlevels of FUT8 and core-fucosylated glycoproteins increase in cases of oral cancer relativeto normal cases. In this study we aim to discover novel core-fucosylated glycoproteinbiomarkers for oral cancer diagnosis with glycoproteomic approaches. First, forty plasmasamples obtained from the Human Bioinformation Bank of NCKUH were subjected to AAL(Aleuria aurantia lectin) affinity chromatography. Core-fucosylated proteins were collectedand applied for LC-MS/MS followed by electrophoresis. Fourteen proteins were identified,and expression levels of proteins in plasma were verified by western blot. Expression levelsof some glycoproteins were elevated in the oral cancer group, including ceruloplasmin,haptoglobin, and leucin-rich alpha-2-glycoprotein 1 (LRG1). However, levels of some glycoproteinsdecreased in the cancer group, including apolipoprotein A-I (apo A-I) andapolipoprotein A-IV (apo A-IV). Via ELISA analysis, we found that apo A-IV and apo A-IV/total protein ratios were decreased in plasma accompanied with cancer stages. TheLRG1/total protein ratio was found to increase while plasma levels of LRG1 were not foundto differ between the oral cancer plasma and normal groups. An ROC curve analysis reveals strong diagnosis performance when combining apo A-IV levels and LRG1/total proteinratios. Taken together, apo A-IV and LRG1, given their strong performance in detecting oralcancer, can serve as useful biomarkers and may be used as a useful tool for oral cancerscreening and early diagnosis.