Proteomic analysis of liver cancer cells treated with suberonylanilide hydroxamic acid

Suberonylanilide hydroxamic acid (SAHA) is an orally administered histone deacetylase inhibitor (HDACI) that has shown significant antitumor activity in a variety of tumor cells. To evaluate if SAHA has an activity against liver cancer, and with an aim to identify the altered cellular factors upon SAHA treatment, human HepG2 cancer cell line was used as a model, and proteomic approach was utilized to elucidate the molecular mechanisms underlying SAHA's antitumor activity.

Cell growth inhibition was measured by MTT method, and apoptosis was detected by means of flow cytometry analysis and TUNEL assay. Protein expression profiles were analyzed by 2-DE coupled with MALDI-Q-TOF MS/MS analysis.

A total of 55 differentially expressed proteins were visualized by 2-DE and Coomassie Brilliant Blue (CBB) staining. Of these, 34 proteins were identified via MS/MS analysis. Among the identified proteins, six proteins also displayed significant expression changes at earlier time points upon SAHA treatment, and such alterations were further confirmed by semi-quantitative RT-PCR. Together, at both the mRNA and protein levels, SAHA suppressed the expression of reticulocalbin 1 precursor (RCN1), annexin A3 (ANXA3) and heat shock 27 kDa protein 1 (HSP27), while increasing the expression of aldose reductase (AR), triosephosphate isomerase 1 (TPI) and manganese superoxide dismutase (SOD2).

SAHA remarkably inhibited proliferation of HepG2 cancer cells, and induced apoptosis in vitro. Using proteomics approaches, a variety of differentially expressed proteins were identified in HepG2 cancer cells before and after treatment with SAHA. This study will enable a better understanding of the molecular mechanisms underlying SAHA-mediated antitumor effects at the protein level.