gamma-sitosterol and Stomach-Neoplasms

We investigated the anti-cancer effects of beta-sitosterol (BS), a plant-derived sterol in AGS human gastric adenocarcinoma cells and xenograft mouse models. BS significantly reduced cell viability by inducing apoptosis in AGS adenocarcinoma cells. This was accompanied by the formation of apoptotic bodies, as detected by Annexin V, caspase 3/7 activity, and MitoPotential assay. BS stimulated phosphatase and tensin homolog (PTEN) and phospho-AMP-activated protein kinase (p-AMPK) expression. Pharmacological inhibitors or siRNA were used to further analyse the relationship between the two proteins. AMPK was found to represent a likely upstream regulator of PTEN. Additionally, two-dimensional gel electrophoresis was used to identify related proteins in the treatment of BS. The decrease of Hsp90 protein by BS was observed. Induction of PTEN protein and reduction of Hsp90 was mediated by AICAR, an AMPK activator, indicating that AMPK is necessary for PTEN and Hsp90 expression. Additionally, BS was found to be effective through the regulation of cancer biomarker. Furthermore, BS suppressed tumour growth without toxicity in the AGS xenograft mouse models-. Taken together, the present results demonstrate that BS exerts anti-cancer effects in AGS cells and xenograft mouse models by mediating AMPK, PTEN, and Hsp90.

Topics: Adenocarcinoma; Adenylate Kinase; Animals; Apoptosis; Biomarkers, Tumor; Cell Line, Tumor; Cell Survival; Gene Expression Regulation, Neoplastic; HSP90 Heat-Shock Proteins; Humans; Hypolipidemic Agents; Male; Mice; Mice, Nude; Neoplasms, Experimental; PTEN Phosphohydrolase; Sitosterols; Stomach Neoplasms

Beta-sitosterol is an important phytosterol found in plant food. It has been shown to have antiproliferative effects on cancers of the colon, breast, and prostate, but its effect on stomach cancer cells in vitro is unknown. Proliferation, cytotoxicity, and apoptosis in SGC-7901 human stomach cancer cells were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, clone formation, lactate dehydrogenase (LDH) leakage assay, acridine orange (AO)/ethidium bromide (EB) double staining, 4',6-diamidine-2'-phenylindole dihydrochloride (DAPI) staining, comet assay, and Western blotting. The results showed that beta-sitosterol suppresses the proliferation and induces the cell cytotoxicity of SGC-7901 stomach cancer cells in a time- and dose-dependent manner. Cells treated with different concentrations of beta-sitosterol also showed changes typical of apoptosis: morphological changes, DNA damage, increased expression of pro-caspase-3 and bax (p < 0.05), and activation of pro-caspase-3 and suppression of bcl-2 expression (p < 0.05). This study therefore revealed that beta-sitosterol significantly inhibits the growth and induces the apoptosis of SGC-7901 human stomach cancer cells in vitro. The decrease of the bcl-2/bax ratio and DNA damage may be the critical mechanisms of apoptosis induced by beta-sitosterol in SGC-7901 human stomach cancer cells.

Topics: Apoptosis; Cell Proliferation; Down-Regulation; Gene Expression Regulation, Neoplastic; Humans; Sitosterols; Stomach Neoplasms