OBJECTIVESTo investigate the differentially expressed mitochondrial proteins in hydroxycamptothecin (HCPT)-treated SMMC-7721 cells by using quantitative proteome.

METHODSSMMC-7721 cell apoptosis was induced by HCPT and the mitochondria were isolated with a mitochondria isolation kit. Mitochondrial proteins labeled with a cleavable isotope-coded affinity tag were identified and quantified using two-dimensional liquid chromatography/tandem mass spectrometry.

RESULTSHighly purified mitochondria were obtained. Seventy-four mitochondrial proteins, which were statistically significantly altered (P less than 0.05) in HCPT-treated cells, were identified and analyzed. A total of 42 proteins were significantly down-regulated, and 32 were up-regulated in the cells that responded to apoptosis. The functions of these proteins were likely involved in cell energy metabolism, nucleic acid translation and transcription, cytoskeleton, etc.

CONCLUSIONOur results about the information of differentially expressed mitochondrial proteins in HCPT-treated cells and the control cells will help to understand the mechanism by which HCPT induces cell apoptosis. The integrated techniques we used in this study will be helpful to the investigation of subcellular quantitative proteomics.