FIGURE 4.

EGCG-induced PP2A activation regained the sensitivity of BRAF inhibitor (PLX4720). A, phosphorylation level and expression of P70S6k and S6 were analyzed by Western blot analysis. B, melanoma cells were treated with PLX4720 of for 48 h, and the phosphorylation level of P70S6k, S6 and ERK1/2 were analyzed by Western blot analysis. C, Hs294T cells were treated with EGCG for 24 h, and the activity of PP2A was measured. D, Hs294T cells were treated with EGCG for 96 h in the presence or absence of OA. E, Hs294T cells were treated with EGCG (5 μm) of and the phosphorylation levels of P70S6k and S6 were analyzed by Western blot analysis. F, Hs294T cells were treated with EGCG for 48 h in the presence or absence of OA, and the phosphorylation levels of P70S6k and S6 were measured. G, Hs294T cells were treated with EGCG, PLX4720, or EGCG/PLX4720 in combination for 96 h. H, NHEM were treated with EGCG or rapamycin (Rapa.) alone or combined with PLX4720 for 96h. I, Hs294T cells were treated with EGCG or rapamycin for 24 h. J, Hs294T cells were treated with EGCG, rapamycin, or PLX4720 alone, or in combination for 14 days for long term colony formation assay. K–N, effect of PLX4720 and EGCG combination on the tumor growth (K), tumor weight (L), p70S6k and ERK phosphorylation (n = 4) (M), aspartate transaminase (AST) and alanine aminotransferase (ALT) (N) of mice on day 33 after inoculation. O, signaling pathway schematic. Error bars, S.D. in vitro or S.E. in vivo (n = 3 per group in vitro or n = 7 per group in vivo). *, p < 0.05; **, p < 0.01; *** or ###, p < 0.001. DMSO, dimethyl sulfoxide; n.s., not significant.