A Serotype 5/3 Adenovirus Expressing MDA-7/IL-24 Infects Renal Carcinoma Cells and Promotes Toxicity of Agents That Increase Ros and Ceramide Levels

Agents that generate reactive oxygen species (ROS) are recog-nized to enhance MDA-7/IL-24 lethality. The present studies fo-cused on clarifying how such agents enhanced MDA-7/IL-24 tox-icity in renal cell carcinoma cells (RCCs). Infection of RCCs with a tropism-modified serotype 5/3 adenovirus expressing MDA-7/ IL-24 (Ad.5/3-mda-7) caused plasma membrane clustering of CD95 and CD95 association with pro-caspase 8, effects that were enhanced by combined exposure to 17-N-allylamino-17-demethoxygeldanamycin (17AAG), As2O3, or fenretinide and that correlated with enhanced cell killing. Knockdown of CD95 or expression of cellular FADD (Fas-associated protein with death domain)-like interleukin-1–converting enzyme inhibitory protein, short form (c-FLIP-s) blocked enhanced killing. Inhibition of ROS generation, elevated cytosolic Ca2, or de novo ceramide synthe