Figure 6. Targeting IL-6/STAT3 activation by JAK2 inhibitors reverses stemness and self–renewal properties in vivo.
(A) Experimental plan of JAK2 inhibitor (NVP) treatment of prostatospheres derived from ESE3KD-PrECs cells during SFA. (B) SFE of ESE3KD-PrECs and ESE3KD-RWPE-1 cells upon treatment described in A. (C) Experimental plan of the treatment with JAK2 inhibitor in vivo. Prostatospheres obtained from SFA were dissociated and injected subcutaneously in NSG mice (n = 4/group). Tumors formed by ESE3KD-PrECs prostatospheres cells (G1 xeno) were dissociated and re-implanted (2 × 105 cells/site) in NSG mice (n = 4/group) for two consecutive generations (G2 xeno and G3 xeno). Treatment was initiated 21 days post-engraftment of the G3 xeno and continued as indicated (lower panel). (D–E) Tumor growth determined by caliper (D) and tumor weight (E) of G3 xeno following treatment as described in C. (F) IL-6 evaluation by qRT-PCR in ESE3KD prostatospheres and G1-G3 xeno. (G) IL-6 evaluation by qRT-PCR in control (CTRL) and following treatment with JAK2 inhibitor. (H–I). SFE ex vivo (H) and flow cytometry analysis of STAT3-Tyr705 staining (I) following JAK2 treatment described in C. P values were determined using t-test. *P < 0.05; **P < 0.01. Data are representative of three independent experiments with at least three replicates per experiment. Percentages of positive cells are shown.