Intratumoral electroinjection of Stat3-3 siRNA resulted in significant inhibition of cancer growth and induced apoptosis of cancer cells in vivo. (A) Mice treated with scrambled vectors had visible cancers, whereas mice treated with 20 μg of stat3-3siRNA vectors had reduced tumor volumes. (B) Growth curves of cancer cells treated with stat3-3 siRNA. Mice were inoculated subcutaneously with SKOV3 cell. On day 12, the mean volume of palpable cancers reached 50.56±36.45 mm3 (n=6) at the sites of injection. Then, these mice were injected intratumorally with buffer, stat3-3 siRNA or scrambled siRNA. Injection was repeated on days 19 and 26, and the tumor sizes were determined on days 0, 5, 12, 19, 26 and 33. (Mean±SEM. n=6, P<0.01). (C, D) HE staining (100×). (E, F) TUNEL staining (200×).