PKC induces STAT3 S727 phosphorylation and Mcl-1 transcription in CLL cells. (A) Inhibiting PKC and blocking the IL-6R inhibits STAT3 phosphorylation and Mcl-1 expression. CLL cells were incubated for 12 hours in the presence or absence of 1μM BisI and/or 0.5μM anti–IL-6R antibody, or IgG1 isotype control. Lysates of these cells were then probed by Western blot with the indicated antibodies. (B) Graphical representation of the data shown in panel A. These data highlight the down-regulation of pS727-STAT3 levels that are observed in CLL cells after treatment with BisI. (C) Graphical representation of the data shown in panel A. These data highlight the down-regulation of Mcl-1 protein levels that are observed in CLL cells after treatment with BisI. (B-C) Results are representative of 3 different CLL patient samples and are expressed relative to IgG1 isotype control (mean ± SEM). Statistical significance was determined using a Student t test.
