Tounongsan extract induces apoptosis in cultured Raji cells

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

The 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.

TNSE 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.

TNSE 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.