Identification of prognosis-related proteins in advanced gastric cancer by mass spectrometry-based comparative proteomics.
OBJECTIVE
The objective of this study was to identify differentially expressed proteins of advanced gastric cancer from patients with different prognosis using NanoLC-MS/MS (LTQ) (nanoflow liquid chromatography system interfaced with a linear ion trap LTQ mass spectrometer).


METHODS
Eight gastric cancer patients with relatively early TNM stage and survival time >34 months were identified as good survival (group G), while the other eight with late stage and survival time <15 months as poor survival (group P). The total protein of the tissue samples from each group was extracted and pooled together respectively. The resulting two protein mixtures were trypsin-digested and analyzed using NanoLC-MS/MS (LTQ). Database searches were done against NCBI non-redundant database and SWISS-PROT database and the identified proteins were classified through an online Web Gene Ontology Annotation Plot tool. Immunohistochemistry was used to verify candidate prognosis-related proteins.


RESULTS
There were 284 and 213 proteins identified for group G and group P respectively. And 117 proteins were detected exclusively in group G and 46 proteins exclusively in group P. These protein markers function in calcium ion signaling pathway, cellular metabolism, cytoskeleton formation, stress reaction, etc. Among those, the down-regulated expression of S100P was verified to claim a poor clinical outcome of gastric cancer patients (P = 0.0375).


CONCLUSIONS
The MS-based proteomics approach is efficient in identifying differentially expressed proteins in relation to prognosis of advanced gastric cancer patients. These differentially expressed proteins could be potential prognosis-related cancer markers and deserve further validation and functional study.
Jia
Shu-Qin
SQ
Department of Surgery, Beijing Cancer Hospital, Beijing Institute for Cancer Research, Peking University School of Oncology, 100036, Beijing, China.
Niu
Zhao-Jian
ZJ
Zhang
Lian-Hai
LH
Zhong
Xi-Yao
XY
Shi
Tao
T
Du
Hong
H
Zhang
Gui-Guo
GG
Hu
Ying
Y
Su
Xiu-Lan
XL
Ji
Jia-Fu
JF
D000328:Adult; D000368:Aged; D002853:Chromatography, Liquid; D005260:Female; D005743:Gastrectomy; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics*; D009367:Neoplasm Staging; D011379:Prognosis; D011506:Proteins / Q000235:genetics*; D040901:Proteomics; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D016019:Survival Analysis; D017741:Survivors
D009363:Neoplasm Proteins; D011506:Proteins