title: Candidate serological biomarkers for cancer identified from the secretomes of 23 cancer cell lines and the human protein atlas.
abstract: Although cancer cell secretome profiling is a promising strategy used to identify potential body fluid-accessible cancer biomarkers, questions remain regarding the depth to which the cancer cell secretome can be mined and the efficiency with which researchers can select useful candidates from the growing list of identified proteins. Therefore, we analyzed the secretomes of 23 human cancer cell lines derived from 11 cancer types using one-dimensional SDS-PAGE and nano-LC-MS/MS performed on an LTQ-Orbitrap mass spectrometer to generate a more comprehensive cancer cell secretome. A total of 31,180 proteins was detected, accounting for 4,584 non-redundant proteins, with an average of 1,300 proteins identified per cell line. Using protein secretion-predictive algorithms, 55.8% of the proteins appeared to be released or shed from cells. The identified proteins were selected as potential marker candidates according to three strategies: (i) proteins apparently secreted by one cancer type but not by others (cancer type-specific marker candidates), (ii) proteins released by most cancer cell lines (pan-cancer marker candidates), and (iii) proteins putatively linked to cancer-relevant pathways. We then examined protein expression profiles in the Human Protein Atlas to identify biomarker candidates that were simultaneously detected in the secretomes and highly expressed in cancer tissues. This analysis yielded 6-137 marker candidates selective for each tumor type and 94 potential pan-cancer markers. Among these, we selectively validated monocyte differentiation antigen CD14 (for liver cancer), stromal cell-derived factor 1 (for lung cancer), and cathepsin L1 and interferon-induced 17-kDa protein (for nasopharyngeal carcinoma) as potential serological cancer markers. In summary, the proteins identified from the secretomes of 23 cancer cell lines and the Human Protein Atlas represent a focused reservoir of potential cancer biomarkers.
authors.affiliation: Molecular Medicine Research Center, Chang Gung University, Tao-Yuan 333, Taiwan.
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Wu
authors.forename: Chia-Wei
authors.initials: CW
authors.lastname: Hsu
authors.forename: Chi-De
authors.initials: CD
authors.lastname: Chen
authors.forename: Chia-Jung
authors.initials: CJ
authors.lastname: Yu
authors.forename: Kai-Ping
authors.initials: KP
authors.lastname: Chang
authors.forename: Dar-In
authors.initials: DI
authors.lastname: Tai
authors.forename: Hao-Ping
authors.initials: HP
authors.lastname: Liu
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Su
authors.forename: Yu-Sun
authors.initials: YS
authors.lastname: Chang
authors.forename: Jau-Song
authors.initials: JS
authors.lastname: Yu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D002403:Cathepsins / Q000097:blood; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D054377:Chemokine CXCL12 / Q000097:blood; D016000:Cluster Analysis; D016207:Cytokines / Q000097:blood; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000097:blood; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000166:cytology; D009363:Neoplasm Proteins / Q000097:blood* / Q000378:metabolism*; D009369:Neoplasms / Q000097:blood* / Q000378:metabolism*; D040901:Proteomics; D015203:Reproducibility of Results; D015398:Signal Transduction; D014452:Ubiquitins / Q000097:blood; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D054377:Chemokine CXCL12; D016207:Cytokines; D018950:Lipopolysaccharide Receptors; D009363:Neoplasm Proteins; D014452:Ubiquitins; C074034:ISG15 protein, human; D002403:Cathepsins