Figure 2

Tet-On system-controlled sTRAIL expression induces apoptosis in tumor cells. (A) MDA-MB-231, U251, SMMC-7721, SMMC-7402, A549 and HepG2 cells were exposed for 24 h to the supernatant of HEK293T cells that have infected with rAAV-TRE-TRAIL&AAV-Tet-On at 2 × 105 GPs per cell for 72 h. Supernatant of HEK293T cells infected with rAAV-TRE- EGFP&AAV-Tet-On and rAAV-CAG-TRAIL were used as negative and positive control, respectively. Cell viability was measured by MTT assay. Results are presented as the mean ± standard deviation of three individual experiments in each group. Dox+, 1 μg/ml doxycycline in the cell culture medium; Dox-, without doxycycline in the medium. (B) Infection with rAAV-TRE-TRAIL&AAV-Tet-On/Dox + induced apoptosis and the time course of virus infection.