Mining the gastric cancer secretome: identification of GRN as a potential diagnostic marker for early gastric cancer.
Gastric cancer is the second leading cause of cancer deaths worldwide, and currently, there are no clinically relevant biomarkers for gastric cancer diagnosis or prognosis. In this study, we applied a 2D-LC-MS/MS based approach, in combination with iTRAQ labeling, to study the secretomes of the gastric cancer cell lines AGS and MKN7. By performing a comparative analysis between the conditioned media and the whole cell lysates, our workflow allowed us to differentiate the bona fide secreted proteins from the intracellular contaminants within the conditioned media. Ninety proteins were found to have higher abundance in the conditioned media as compared to the whole cell lysates of AGS and MKN7 cells. Using a signal peptide and nonclassical secretion prediction tool and an online exosome database, we demonstrated that up to 92.2% of these 90 proteins can be exported out of the cells by classical or nonclassical secretory pathways. We then performed quantitative comparisons of the secretomes between AGS and MKN7, identifying 43 differentially expressed secreted proteins. Among them, GRN was found to be frequently expressed in gastric tumor tissues, but not in normal gastric epithelia by immunohistochemistry. Sandwich ELISA assay also showed elevation of serum GRN levels in gastric cancer patients, particularly those with early gastric cancer. Receiver operating characteristic (ROC) curves analysis confirmed that serum GRN can provide diagnostic discriminations for gastric cancer patients.
Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore , 8 Medical Drive, Singapore 117597.
Hendrick
H
Loei
Hwee Tong
HT
Tan
Teck Kwang
TK
Lim
Kiat Hon
KH
Lim
Jimmy Bok-Yan
JB
So
Khay Guan
KG
Yeoh
Maxey C M
MC
Chung
D000230:Adenocarcinoma / Q000097:blood* / Q000175:diagnosis / Q000378:metabolism; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood* / Q000378:metabolism; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D000077153:Progranulins; D020543:Proteome / Q000378:metabolism; D012372:ROC Curve; D055571:Secretory Pathway; D013274:Stomach Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000378:metabolism; D046888:Tissue Array Analysis
D014408:Biomarkers, Tumor; D017077:Culture Media, Conditioned; C492314:GRN protein, human; D036341:Intercellular Signaling Peptides and Proteins; D000077153:Progranulins; D020543:Proteome