beta-hederin and Lung-Neoplasms

Chemoresistance is a major limiting factor that impairs the outcome of non-small cell lung cancer (NSCLC) chemotherapy. Paclitaxel (Tax) induces protective autophagy in NSCLC cells, leading to the development of drug resistance. We recently identified a new autophagy inhibitor (alpha-hederin) and hypothesized that it may promote the killing effect of Tax on NSCLC cells. We found that alpha-hederin (α-Hed) could block late autophagic flux in NSCLC cells by altering lysosomal pH and inhibiting lysosomal cathepsin D maturation. Combination treatment of α-Hed and Tax synergistically reduced NSCLC cell proliferation and increased NSCLC cell apoptosis compared with treatment with α-Hed or Tax alone. Furthermore, α-Hed plus Tax enhanced the accumulation of intracellular reactive oxygen species (ROS) in NSCLC cells, while the ROS inhibitor N-acetylcysteine reversed the inhibitory effect of the combination treatment. Our findings suggest that α-Hed can increase the killing effect of Tax on NSCLC cells by promoting ROS accumulation, and that combining α-Hed with classical Tax represents a novel strategy for treating NSCLC.

Topics: Apoptosis; Autophagosomes; Autophagy; Carcinoma, Non-Small-Cell Lung; Cathepsins; Cell Line, Tumor; Cell Proliferation; Humans; Hydrogen-Ion Concentration; Lung Neoplasms; Lysosomes; Oleanolic Acid; Paclitaxel; Reactive Oxygen Species; Saponins; Tubulin Modulators

We synthesized a diosgenyl saponin bearing a unique disaccharide from the natural product β-hederin, together with twelve glycosylated derivatives and determined their cytotoxicity against five different human cancer cell lines. Most of them showed weak cytotoxicity, with the exception of compound , diosgenyl α-L-rhamnopyranosyl-(1→2)-[α-L-arabinopyranosyl-(1→4)]-α-L-arabinopyranoside, which exhibited strong cytotoxicity against A549 cells. The cytotoxicity of was associated with apoptotic cell death, which was characterized by morphological changes, chromatin condensation, DNA fragmentation, and phosphatidylserine externalization. Compound 20 induced apoptosis of A549 cells through a caspase-8-mediated extrinsic pathway and a caspase-9-mediated intrinsic pathway. In addition, phosphorylation of JNK increased but the phosphorylation of ERK decreased after treatment with 20. These results provide a basic mechanism for the anticancer activity of 20.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Antineoplastic Agents; Apoptosis; Caspase 8; Caspase 9; Cell Line, Tumor; DNA Fragmentation; Glycosylation; Humans; Lung; Lung Neoplasms; Oleanolic Acid; Saponins