Cardiac Glycoside Compound Isolated from Helleborus thibetanus Franch Displays Potent Toxicity against HeLa Cervical Carcinoma Cells through ROS-Independent Autophagy.

Abstract

The current study aimed to examine the anticancer activity of HTF-1, a cardiac glycoside (CG) isolated from Helleborus thibetanus Franch, using a cell-based model and to discover the underlying mechanisms with specific focus on autophagy. We found that HTF-1 was able to potently decrease the viability of several cancer cell lines especially for HeLa cervical carcinoma cells. It was discovered that HTF-1 dose dependently induced overproduction of ROS in HeLa cells, and the cell viability can be rescued when adding ROS scavenger N-acetyl-l-cysteine (NAC). More, we found that HTF-1 induced ROS-independent autophagy in concentration- and time-dependent manners in HeLa cells. This can be collectively verified by LC3-II and p62 abundance and also eGFP-LC3 puncta assay, bafilomycin clamp experiment, and acidotropic dye fluorescent labeling experiment. Additionally, TEM examination showed more autophagic vacuoles for HTF-1-treated HeLa cells. In HeLa cells, pretreatment with wortmannin (an inhibitor of the initial stages of autophagy to block autophagosome formation, thus, it should weaken the autophagy induction effect of HTF-1) decreased the autophagic flux and partially antagonized cell death induced by HTF-1, indicating that autophagy induced by HTF-1 played a cancer-suppressing role. Furthermore, coadministration of BAF (as a distal inhibitor of autophagy) with HTF-1 demonstrated a synergistic anticancer effect against HeLa cells. We believe that our work will enrich the understanding of CGs and especially anticarcinoma activity, also, pave the way for natural-product-based anticancer drug development.

• Authors: Shuli Man, Haiyue Wang, Jin Zhou, Yingying Lu, Yanfang Su, Long Ma
• Journal: Chemical research in toxicology (Chem Res Toxicol) Vol. 32 Issue 12 Pg. 2479-2487 (12 16 2019) ISSN: 1520-5010 [Electronic] United States
• PMID: 31714069 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• Cardiac Glycosides
• Macrolides
• Reactive Oxygen Species
• bafilomycin A1
• Acetylcysteine

Topics

• Acetylcysteine (pharmacology)
• Antineoplastic Agents (pharmacology)
• Autophagy (drug effects)
• Cardiac Glycosides (pharmacology)
• Cell Line, Tumor
• Cell Survival (drug effects)
• Helleborus (chemistry)
• Humans
• Macrolides (pharmacology)
• Reactive Oxygen Species (metabolism)