Targeting Stat3 suppresses growth of U251 cell-derived tumours in nude mice.

Malignant gliomas are highly invasive tumours associated with high levels of mortality, and the treatment of gliomas remains a major neurosurgical challenge. Stat3, a member of the signal transducer and activator of transcription family, has a critical role in a variety of cancer cells. We have previously shown that downregulation of Stat3 decreases invasiveness and induces apoptosis in U251 human glioma cells in vitro, but to date it has been unclear whether this treatment would be beneficial in vivo. In the present study, we found that downregulation of Stat3 via RNAi suppressed tumour growth in a xenograft mouse model by inducing apoptosis of U251 tumour cells and inhibiting tumour neo-angiogenesis. We also found that Stat3 RNAi suppresses the expression of Bcl-2 in vivo to induce apoptosis. These results indicate that Stat3 is a critical factor in the survival of patients with glioma, and that targeting Stat3 may offer a potential therapeutic approach.