Comparative study of proteome between primary cancer and hepatic metastatic tumor in colorectal cancer.
OBJECTIVE
To identify the differential proteins associated with colorectal cancer genesis and hepatic metastasis.


METHODS
Hydrophobic protein samples were extracted from normal colorectal mucosa, primary cancer lesion and hepatic metastatic foci of colorectal cancer. With two-dimensional electrophoresis and image analysis, differentially expressed protein spots were detected, and the proteins were identified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry and peptide mass fingerprint analysis.


RESULTS
Significant alterations of the proteins in number and expression levels were discovered in primary cancer and hepatic metastatic foci, the expression of a number of proteins was lost in 25-40 ku, but protein spots was increased in 14-21 ku, compared with normal mucosa. Nine differentially expressed protein spots were identified. Three proteins expressed in normal mucosa, but lost in primary cancer and hepatic metastasis, were recognized as calmodulin, ribonuclease 6 precursor and mannosidase-alpha. Proapolipoprotein was expressed progressively from normal mucosa to primary cancer and hepatic metastasis. The differentially expressed protein of beta-globin was found in normal mucosa and hepatic metastatic tumor, but lost in primary cancer lesion. Cdc 42, a GTP-binding protein, was identified in hepatic metastasis. The protein spots of C4 from primary cancer, M7 and M9 from hepatic metastasis had less homology with the proteins in database.


CONCLUSIONS
Variations of hydrophobic protein expression in colorectal cancer initiation and hepatic metastasis are significant and can be observed with two-dimensional electrophoresis. The expression of calmodulin, ribonuclease 6 precursor and mannosidase-alpha is lost but the expression of proapolipoprotein is enhanced which is associated with colorectal cancer genesis and hepatic metastasis. Cdc 42 and beta-globin are expressed abnormally in hepatic metastasis. Protein C4, M7 and M9 may be associated with colorectal cancer genesis and hepatic metastasis.
Department of General Surgery, General Hospital of Beijing Military Command, Beijing 100700, China. yubo66@126.com
Bo
B
Yu
Shi-Yong
SY
Li
Ping
P
An
Ying-Nan
YN
Zhang
Zhen-Jia
ZJ
Liang
Shu-Jun
SJ
Yuan
Hui-Yun
HY
Cai
D000328:Adult; D000368:Aged; D003110:Colonic Neoplasms / Q000737:chemistry* / Q000473:pathology*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000737:chemistry* / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D010449:Peptide Mapping; D020543:Proteome / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D020543:Proteome