Tumor Cell Death via Apoptosis and Improvement of Activated Lymphocyte Cytokine Secretion by Extracts from Euphorbia Hebecarpa and Euphorbia Petiolata.

BACKGROUND: Immunomodulatory materials from natural herbs and the characterization of their immune enhancement<br />effects may have tremendous potential as cancer treatment. The aim of the present study was to investigate the<br />apoptosis-inducing activities of Euphorbia hebecarpa Boiss and Euphorbia petiolata Banks & Sol. plant extracts and<br />their effects on cytokine secretion by lymphocytes.

MATERIALS AND METHODS: We assessed the apoptosis-inducing<br />effect of the plants' hexane extracts on previously determined sensitive cell lines (HeLa for E. hebecarpa and K562<br />for E. petiolata) by flow cytometry and measurement of caspase 3 activation. The apoptosis-related gene expressions<br />were examined by real-time PCR. The effects of the extracts on lymphocyte proliferation and cytokine secretion were<br />examined.

RESULTS: Flow cytometry analysis showed that the inhibitory effect of the extracts on tumor cell growth<br />was due to cell apoptosis. The plant extracts at the 100 μg/ml dose induced apoptosis in HeLa (98.5 ± 0.1%) and K562<br />(57.7 ± 1.9%) cells. The extracts increased caspase 3 activation (≈2-fold>control). Real-time PCR showed Fas and Bax<br />gene upregulation and Bcl-2 downregulation, which resulted in an increased Bax/Bcl-2 expression ratio. The extracts<br />increased lymphocyte proliferation and increased levels of IFN-γ production in the presence and absence of mitogen<br />(p < 0.05). They significantly increased IL-4 and decreased IL-10 secretion by mitogen-stimulated lymphocytes.<br />E. hebecarpa also increased IL-17 release.

CONCLUSION: These results have shown that both extracts possess antitumor<br />activity by inducing apoptosis, possibly through both intrinsic and extrinsic pathways. In addition, they induced secretion<br />of different T helper subset related cytokines that are effective in the immune response against cancer.