Figure 7

GSIXII induced apoptosis in primary breast tumor cells in ex vivo assay. Active caspase-3 immunostaining analyzed with immunohistochemistry in one of the human breast tumors 48 hours after 15 μM GSIXII treatment or untreated (Ct). Magnification, ×200 and ×400. (A) 23 ER⁺ (Δ) or 7 ER^- (▲) primary human tumor samples were cultured 48 hours with 15 μM GSIXII or not treated (Ct), as described in Materials and methods, and then analyzed for active caspase-3 with immunohistochemistry. Data are represented as percentage of tumoral cells positive for active caspase-3 immunostaining in each specimen. (B) Noxa expression was induced in breast tumor samples after 48-hour GSIXII treatment compared with the untreated condition, as shown in two samples assessed with immunoblot analysis. (C) The GSIXII and ABT-737 combination enhanced apoptosis triggering in breast cancer tumors. Six human primary tumor samples (three ER⁺ and three ER^-) were cultured for 48 hours with or without 15 μM GSIXII in combination with 1 μM ABT 737 or not for 48 hours, in ex vivo assay. The percentage of active caspase-3-positive tumoral cells was then established with immunohistochemistry. A one-way ANOVA test performed on the presented cohort of tumors indicates that the combination (GSIXII+ABT-737) was significantly better than either GSIXII or ABT-737 single treatment (** and ***, respectively).