1. Signals and transcription factors involved in B-cell PD-1 induction.
Signals and transcription factors involved in B-cell PD-1 induction. A, FACS analysis of BCL6 expression in PD-1−, PD-1dim, and PD-1hi B cells from HCC tumor tissue. Results show mean ± SEM of B cells from four patients. B, FACS analysis of STAT6 activation status in HCC tumor B cells (N = 4), with peripheral B cells treated with 10 ng/mL IL4 for 15 minutes as a positive control. C and D, B cells from healthy blood donors were left untreated or exposed to primary HCC-SN (C), or exposed to various TLR agonists or cytokines (D) for 48 hours. Thereafter, BCL6 expression and STAT6 activation were determined by immunoblotting. Results represent four independent experiments (N = 5). E and F, using a pSIF-H1-CopGFP-shBCL6 lentiviral vector to silence BCL6 largely attenuated the HCC-SN–mediated induction of PD-1+/hi B cells (E), and knockdown of STAT6 effectively rescued the IL4-elicited PD-1 inhibition (F). Data are given as mean ± SEM of four independent experiments (N = 5 for E, N = 4 for F). G, primary HCC-SN induced vigorous activation of AKT, MAPKs, and NFκB in healthy blood B cells. Results represent three independent experiments (N = 4). H, inhibition of JNK, NFκB, and p38 suppressed B-cell BCL6 expression and subsequent PD-1 expression induced by primary HCC-SN. Data are given as mean ± SEM of three independent experiments (N = 4). Statistics were compared with DMSO controls. *, P < 0.05; **, P < 0.01; ***, P < (Student t test).
Xiao Xiao et al. Cancer Discov 2016;6:
©2016 by American Association for Cancer Research