Figure 7.

Digested Chaga extract impaired HER2 activation and acted synergistically with trastuzumab and cisplatin. (A) Representative Western blotting showing the expression of HER2, phospho-HER2, phospho-HER1, and β-actin (loading control) in SK-BR-3 cells, left untreated (Ctrl) or treated with 1 mg/mL of digested Chaga extract (MW < 3500 Da) for 2 h, 6 h, or 24 h. Twenty micrograms of proteins/well were loaded. (B) SK-BR-3 cells were plated onto 96-well plates, treated with increasing concentrations of trastuzumab alone or in combination with a fixed, sub-toxic concentration (0.25 mg/mL) of digested Chaga extract (MW < 3500 Da); cell viability was determined by MTT assay. (C) SK-BR-3 cells and (D) MDA-MB-231 cells were treated with the indicated concentrations of cisplatin alone or in combination with 0.25 mg/mL digested Chaga extract (MW < 3500 Da); cell viability was determined by MTT assay. Drug interaction was evaluated by the Bliss Independence model; the observed effects of the drug combination indicated synergistic interaction (calculations are reported in Table S3). Bars: SE. * p < 0.05, ** p < 0.01, **** p < 0.0001. ns: not significant. One-way ANOVA followed by Dunnett’s multiple comparison test. Data show a representative of three independent experiments.