Anti-cancer Effect of Hyoscyamus muticus Extract via Its Activation of Fas/FasL-ASK1-p38 Pathway

Abstract

flow cytometric analysis, knockdown of ASK1, and reactive oxygen species (ROS) production were evaluated to clarify the mechanism of action. Phytochemical screening confirmed the presence of wide range of phytoconstituents. Hyoscyamus muticus methanolic extracts (HMME) showed the highest anti-cancer activities against leukemia, breast, renal, and prostate cancers as compared to ethanol and aqueous extracts. Specifically, HMME exerted cytotoxic effect against the MDA-MB-231 and MDA-MB-468 triple-negative breast cancer (TNBC) cell lines with IC50 values of 8.75 and 7.25 μg/mL, respectively. Mechanistically, DAPI staining and flow cytometric analysis revealed that HMME induces apoptosis via the death receptor, FAS, but not the mitochondrial pathway. Moreover, ASK1 and p38 were rapidly activated in response to HMME, and knockdown of ASK1 by a small interference of RNA specific to Ask1 attenuated p38 and caspase-3 activation and suppressed apoptosis, implying that HMME-induced apoptosis relies on the ASK1-p38-caspase-3 pathway. Furthermore, we confirmed that cellular ROS generation was a critical mediator in HMME-induced apoptosis because the ROS- scavenger N-acetyl cysteine significantly decreased the phosphorylation of ASK1 and HMME-induced apoptosis. Our results confirmed HMME cytotoxic effects in TNBCs via ROS-dependent activation of the Fas/FasL-ASK1-p38 axis.