GW806742X

Triple-negative breast cancer（TNBC） lacks estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor (HER2), and traditional treatments cannot accurately target TNBC. Anthracycline- and paclitaxel-based chemotherapeutic agents are still the mainstay of treatment for TNBC, but these chemotherapeutic agents have major toxic side effects and are prone to drug resistance during the treatment of TNBC. In this study, we investigated the efficacy and potential mechanisms of action of GW806742X in the treatment of TNBC. We screened a library of 600 FDA-approved small molecule compounds to identify GW806742X, a small molecule that inhibits the viability of triple-negative breast cancer cells. In vitro, GW806742X was found to be cytotoxic to TNBC cells in a dose-dependent manner and to inhibit the growth of MDA-MB-468 tumors in vivo. Mechanistically, we used PharmMapper to predict the possible targets of GW806742X and demonstrated that the small molecule drug could directly bind to BCL-2 by molecular docking simulations and ITC experiments. Western blot analysis demonstrated that GW806742X could reduce BCL-2 protein levels and possibly promote BCL-2 degradation through the lysosomal pathway. Moreover, GW806742X disrupts NF-κB signaling. In conclusion, this study demonstrates that GW806742X can be a potential therapeutic agent for triple-negative breast cancer by targeting BCL-2.

The dimerization of the MLKL kinase-like domain (KLD) is a crucial step for MLKL activation in necroptosis. In 2014, it was discovered that GW806742X can directly bind to the mouse MLKL KLD via surface plasmon resonance (SPR) (Kd = 9.3 μM), inhibiting TNF-induced membrane translocation of MLKL and necroptosis. Consequently, GW806742X is considered a mouse MLKL inhibitor. In this study, we found that GW806742X blocks TNF-induced RIP1-dependent necroptosis but promotes necroptosis triggered by either RIP3 or MLKL self-oligomerization in the FKBPv chemical dimerizer system. In addition, higher doses of GW806742X can directly induce MLKL-dependent necroptosis and promote MLKL oligomerization, as detected by non-reducing Western blot. Through chemical cross-linking assays, we observed that GW806742X induces dimerization of recombinant mouse MLKL KLD proteins. The dimerization of the MLKL KLD is a direct consequence of RIP3 phosphorylation, a crucial step in RIP3-induced MLKL activation and necroptosis. Therefore, GW806742X exerts a dual effect on necroptosis: it inhibits necroptosis, likely by interfering with RIP1 function, while promoting necroptosis by facilitating MLKL activation.