Deglycosylation Does Not Affect the Cytotoxic Action of Adenoviral Interferon α‐Induced Bystander Proteins

Abstract

We previously reported an indirect effect of adenoviral interferon α (Ad‐IFNα) that is mediated by secreting bystander proteins (BSPs) and causing cytotoxic responses in both interferon α (IFNα)‐sensitive and –resistant cancer cells. Here, we investigated whether glycosylation of BSPs is necessary for the inhibition of IFNα‐resistant human bladder cancer cell line (KU7). The condition medium (CM) from the normal human urothelial cell line, TERT‐NHUC, was collected as described previously and incubated with and without N‐glycosidase F at 37°C (overnight). The growth inhibition of KU7 was compared between the control and experimental conditions. The proliferation of KU7 cells treated with interferon a protein (Intron A) is comparable to the cells treated with control TERT‐NHUC‐CM (without Ad‐IFNα infection) after 72 hr incubation. The growth of KU7 was significantly inhibited by the CM from Ad‐IFNα–infected TERT‐NHUC culture. N‐glycosidase F incubation effectively deglycosylated the BSPs in the CM (Ad‐IFNα TERT‐NHUC) as demonstrated by the band shifting in the PAGE gel verification. The deglycosylated CM (Ad‐IFNα TERT‐NHUC) produced a same degree of inhibition on the proliferation of KU7 cells (Fig 1). In conclusion, the cytotoxic effects of BSPs is independent of its status of glycosylation.