Dynamic alteration of protein expression profiles during neoplastic transformation of rat hepatic oval-like cells

To explore the molecular basis of neoplastic transformation of hepatic oval cells, a proteomic strategy was utilized to examine the global protein expression alterations during neoplastic transformation of rat hepatic oval-like cells. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-initiated WB-F344 cells were treated with H(2)O(2) for neoplastic transformation. The transformed cells were identified by soft agar assay and MTT assay. The subsequent proteomic separation and identification were performed with 2-DE followed by MALDI-TOF-MS/MS analysis. Of the 148 differentially displayed protein spots analyzed, 121 spots representing 79 distinct proteins were finally identified. The expression levels of interested proteins were validated by western blotting including 40 S ribosomal protein A (RPSA) and cytokeratin 8. Bioinformatics annotations indicated that these identified proteins were enriched with oxidoreduction and stress response; transcription, translation, and protein processing; and energy/metabolism functions. Interestingly, 17 of the identified proteins were also found to be involved in early hepatic differentiation of mouse embryonic stem (ES) cells in our previous study. Twenty-six proteins had been reported as being dysregulated in hepatocellular carcinoma and other cancers. It suggested that these changed proteins may be implicated in neoplastic transformation of WB-F344 cells. The results may provide some clues for understanding the molecular mechanisms of hepatocarcinogenesis as viewed from dysregulation of differentiation.