Figure 3. Inhibition of tumor cells by the secreted recombinant interferons.

(A) Quantitation of the secreted IFN in cell supernatants. 293T cells were transfected with SIFα, IFNα, IEP, and vector plasmid DNAs using Lipofectamin 2000. Forty-eight hours after transfection, the cell medium was collected for ELISA quantitation of the secreted IFN. *p < 0.05 as compared with the PBS and IEP controls. (B) Western blot of SIFα. Supernatants (20 μl) collected from the IFNα, SIFα, IEP, and vector-transfected 293T cells (A) were separated on Mini-PROTEIN TGX gradient gel (Bio-Rad, CA), transferred to a nitrocellulose membrane, probed with IFNα antibody, and detected by the Odyssey infrared imaging system. SIFα: 24.4 kD, IFNα: 21.6 kD as estimated by ExPASy (http://web.expasy.org/cgi-bin/compute_pi/pi_tool). (C–D) Inhibition of cell growth of ASPC (B) and CFPAC1 (C) cancer cells using cell supernatants that contain the equal amount of the secreted interferons. Cell growth was measured by sulforhodamine B (SRB)-assay. All data shown are mean ± SD from three independent. *p < 0.05 as compared with the PBS control and with the wild type IFNα group.