CREB inhibits progression of leukemia in vivo. (A) Western blot analysis with CREB and tubulin antisera, demonstrating 2-fold increase in expression of CREB in T315I mutant of Bcr-Abl in murine pro-B lymphocyte line (Ba/F3) compared with wild-type Ba/F3 cells. (B) Western blot analysis after lentiviral transduction with CREB shRNAs demonstrating 90% inhibition. (C) Quantitative reverse transcription-PCR showing diminished CREB mRNA levels in transduced Ba/F3 T315I cells. (D) Trypan blue exclusion method performed in triplicate shows diminished growth after transduction with CREB shRNA compared with empty vector. (E) Bioluminescence imaging of SCID mice injected with 106 cells transduced with CREB shRNA or CREB scrambled shRNA lentivirus. Mice were imaged at days 7 and 14. Tumor burden is lower in CREB shRNA–injected mice. (F) Kaplan-Meier survival analysis of mice injected with 5 × 105 cells showing longer survival with CREB knockdown (n = 9) compared with scrambled shRNA (n = 9). All deaths were due to leukemia, except for a day 7 handling event in the scrambled group treated as a censored observation. Error bars in panels C and D represent SE.
