Background & objective: Colorectal laterally spreading tumor (CLST) rarely invades deeply but always laterally spreads along the colorectal mucosa, therefore, CLST could be used as a comparative model in studying the invasion and metastasis of colorectal cancer (CRC). This study was to identify differentially expressed proteins between a CLST cell line LST-R1 and two colorectal carcinoma cell lines SW480 and LoVo using proteomic technology.
Methods: Total proteins of LST-R1, SW480 and LoVo cells were isolated by two-dimensional electrophoresis (2-DE). Differentially expressed protein spots were analyzed with Melanie 3 software. The peptide mass fingerprints (PMFs) of differently expressed proteins were analyzed by MALDI-TOF mass spectrum. Subsequently matched proteins were searched through protein databases.
Results: Using pH4-7 IPG gels with 250 microg protein loading, the numbers of protein spots in 2-DE maps were 1285+/-51 in LST-R1 cells, 1184+/-47 in SW480 cells, and 1124+/-54 in LoVo cells; when with 150 microg protein loading, the numbers were 989, 935 and 893, respectively. The distribution and levels of these proteins in 2-DE maps of LST-R1, SW480 and LoVo cells were analogical which indicated CLST also expresses the protein profile of common colorectal tumors. In 2-DE maps, 96+/-7 differential protein spots were detected between LST-R1 cells and SW480 cells with 50+/-6 only expressed or obviously over-expressed in LST-R1 cells and 47+/-5 in SW480 cells; 108+/-10 differential protein spots were detected between LST-R1 cells and LoVo cells with 56+/-8 only expressed or obviously over-expressed in LST-R1 cells and 52+/-11 in LoVo cells. Nineteen differentially expressed proteins were identified among LST-R1, SW480 and LoVo cells.
Conclusion: Nineteen differentially expressed proteins are possibly involved in laterally spreading of CLST and adhesion and invasion of CRC.