Identification of RKIP as a differentially tyrosine-phosphorylated protein in nasopharyngeal carcinoma and normal nasopharyngeal epithelial tissues by phosphoproteomic approach.
OBJECTIVE
To screen for differentially tyrosine-phosphorylated proteins between nasopharyngeal carcinoma (NPC) and normal nasopharyngeal epithelial tissues (NNET) to provide a basis for elucidate the molecular mechanisms of NPC carcinogenesis.


METHODS
Two-dimensional (2-D) electrophoresis was applied to separate proteins from NPC and NNET, respectively, and 2-D Western blotting was performed to detect tyrosine-phosphorylated proteins using antiphosphotyrosine antibody. Differentially tyrosine-phosphorylated proteins were identified by electrospray ionization-quadrupole time-of-flight MS (ESI-Q-TOF MS). NetPhos software was used to predict the tyrosine-phosphorylation sites of the identified proteins, and Western blotting was used to detect the tyrosine-phosphorylated levels of RKIP in NPC and NNET.


RESULTS
Twenty-five differentially tyrosine-phosphorylated proteins in the two types of tissues were found, 13 of which were identified by ESI-Q-TOF MS. Among the 13 identified proteins, tyrosine-phosphorylated levels of 7 proteins were increased, and those of 6 proteins were decreased in NPC compared with NNET. NetPhos software prediction showed that all the 13 identified proteins contained tyrosine phosphorylation sites, and the differentially tyrosine-phosphorylated level of RKIP in NPC and NNET was confirmed.


CONCLUSIONS
The 13 differentially tyrosine-phosphorylated proteins may be involved in the development and progression of NPC.
Chen
Yan
Y
Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, China.
Tang
Can-E
CE
Ouyang
Guo-Liang
GL
Ruan
Lin
L
Li
Mao-Yu
MY
Zhang
Peng-Fei
PF
Li
Cui
C
Yi
Hong
H
Peng
Fang
F
Li
Jian-Ling
JL
Chen
Zhu-Chu
ZC
Xiao
Zhi-Qiang
ZQ
D014408:Biomarkers, Tumor / Q000378:metabolism; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000378:metabolism*; D009305:Nasopharynx / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D049488:Phosphatidylethanolamine Binding Protein / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D040901:Proteomics; D021241:Spectrometry, Mass, Electrospray Ionization; D014443:Tyrosine / Q000378:metabolism*
D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; C511482:PEBP1 protein, human; D049488:Phosphatidylethanolamine Binding Protein; D010750:Phosphoproteins; D014443:Tyrosine