Comparative plasma membrane-associated proteomics of immortalized human hepatocytes

This work was initiated with the purpose of purifying and identifying differentially expressed plasma membrane-associated proteins between human liver cancer cell line HepG2 and normal liver cell line L02. The combined strategy of sucrose density gradient centrifugation and subsequent phase partition was applied to obtain high-purity proteins of plasma membrane. Two-dimensional gel electrophoresis revealed the differential protein profile between the two cell lines. A total of 13 plasma membrane-associated proteins containing 10 up-regulated proteins and three down-regulated proteins in HepG2 cells were successfully identified by MALDI-Q-TOF mass spectrometry; they participate in multiple biological functions such as adhesion, proliferation, apoptosis, and signal transduction. The identified proteins could provide helpful reference in clinical investigations on potential candidates for diagnosis and therapy of liver cancer.