Surprisingly, in vitro, Ad-IFNalpha also caused caspase-dependent death of bladder cancer cell lines that were resistant to high concentrations of IFN-alpha protein, including the cell line used in vivo.
The results demonstrate that IFN acts synergistically with ATRA and 9cRA in the growth and apoptosis of bladder cancer cells in vitro and suggest that this combination has a potential for the treatment of transitional cell carcinoma of the bladder.
Here, we investigated whether a component of Ad-IFN-induced cell death involves protein overload-induced endoplasmic reticulum (ER) stress, using an IFNα-resistant human bladder cancer cell line (KU7), and the normal human urothelial cell line, TERT-NHUC, as preclinical models.
RT-qPCR and western blotting demonstrated that cytokines IL-2, IFN-α and IFN-γ markedly upregulated PD-L1 mRNA expression rates and protein levels in bladder cancer T24 cells (P<0.05), but had no significant effect in non-tumor SV-HUC-1 cells.
Our data reveal that IFN-α can exert its antitumor effect through a non-canonical JAK-STAT pathway in the bladder cancer cells with low activity of IFN pathway, and the TPL2 inhibition is another function of IFN-α in the context of bladder cancer therapy.