Figure 5. [Bi-213]anti-CD20 restores deficient caspase activation and apoptotic pathways in CD20-positive NHL cells specifically.

(A,B) [Bi-213]anti-CD20 leads specifically to the activation of the caspase cascade. The CD20-positive (CD20+/+) NHL cell line DoHH-2 (A) as well as the CD20-positive (CD20+/+) NHL beta-radiation resistant cell line DoHH-2^betaR (B) or gamma-radiation resistant cell line DoHH-2^gammaR (B) were either left untreated (Control) or were incubated with different activity concentrations of [Bi-213]anti-CD20 as indicated. (C) The HER2-negative (HER2−/−) NHL cell line DoHH-2 (C) as well as the HER2-negative (HER2−/−) NHL beta-radiation resistant cell line DoHH-2^betaR (C) or gamma-radiation resistant cell line DoHH-2^gammaR (C) were either left untreated (Control) or were incubated with different activity concentrations of [Bi-213]anti-HER2 as indicated. (D) The CD20-negative (CD20−/−) cell line HL-60 was either left untreated (Control) or was incubated with different activity concentrations of [Bi-213]anti-CD20 as indicated. (A,B,C,D) 24h and 48h after applying the antibodies labelled with Bi-213, protein lysates were isolated and Western-blot analyses for caspase-9, -2, -3 and PARP performed. Downregulation of procaspase-2 was detectable at ~48kDa. The active fragment of caspase-9 was detected at ~37kDa, the active fragment of caspase-3 at ~19kDa and ~17kDa and PARP cleavage at ~85kDa. Equal protein loading was controlled using an anti-β-Actin-antibody.