OBJECTIVETo investigate the effects of Tounongsan () extract (TNSE) on proliferation and apoptosis of the human lymphoma cell line Raji and its possible mechanism of action.

METHODSThe viability of TNSE-treated Raji cells was measured by a 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell apoptosis was determined by flow cytometry. The molecular mechanisms of TNSE-mediated apoptosis were further investigated by reverse transcription-polymerase chain reaction (RT-PCR) analysis of the mRNA expression of nuclear factor κB (NF-κB), Bcl-xL, Bcl-2-associated death promoter (Bad), caspase-9 and caspase-3. Western blotting was used to detect the protein expressions of NF-κB, Bad, cleaved caspase-9 and cleaved caspase-3.

RESULTSTNSE inhibited Raji cell proliferation in dose- and time-dependent manners. After 48-h treatment with various concentrations of TNSE (125, 250 and 500 μg/mL), the apoptosis rates of Raji cell were 12.23%±1.98% (P<0.05), 20.97%±3.96% (P<0.01) and 30.4%±4.87% (P<0.01), respectively, compared with those of the control (6.02%±1.01%). RT-PCR demonstrated that NF-κB mRNA expression was significantly downregulated in Raji cells treated with 250 μg/mL TNSE for 48 h (P<0.05), while Bad, caspase-9 and caspase-3 mRNA levels were upregulated (P<0.05). Moreover, TNSE treatment resulted in downregulation of NF-κB protein expression and strikingly upregulated protein expressions of Bad, cleaved caspase-9, cleaved caspase-3 in a dose-dependent manner, as determined by Western blot.

CONCLUSIONTNSE exhibits significant anti-proliferative and apoptotic effects in Raji cells, which may be involved in regulation of NF-κB and Bad, and activation of caspase-9 and caspase-3.