Figure 3.

PCTP is specific in inducing cell death by Kv1.3 inhibition. (A) Jurkat T lymphocytes and leukemic K562 cells were treated for 24 h with PAP-1, PCTP, or PCARBTP at the indicated concentrations with or without the addition of 4 µM cyclosporine H as multidrug resistance pumps inhibitor. Cell death by apoptosis was then determined by incubation with fluorescein isothiocyanate-labeled annexin-V for 20 min at 37°C in the dark. Annexin-V positive cells were measured by FACS analysis (n = 3; ***p < 0.001 vs control). (B) Jurkat cells were either transfected with a control siRNA (Scramble) or siRNA against Kv1.3 (siRNA) and after 48 h from the transfection they were treated as in (A) with PAP-1 and PCTP (n = 3; ***p < 0.001 vs control). Insert: Kv1.3 downregulation was assessed by Western blot after siRNA transfection. A representative image is shown of three independent observations. GAPDH was used as loading control.