Exploring the Ca signaling and cytotoxicity induced by the alantolactone in breast cancer cells and its potential implications in treatment using the Ca chelating agent BAPTA-AM.

Alantolactone, a bioactive sesquiterpene lactone derived from the roots of (elecampane), has garnered attention in biomedical and pharmacological research for its diverse therapeutic properties, including anticancer, anti-inflammatory, antimicrobial, and antioxidant activities. Despite its well-documented bioactivity, the effects of alantolactone on calcium ion (Ca) signaling and the underlying mechanisms in human breast cancer cells remain poorly understood. This study explored how alantolactone influences intracellular Ca levels ([Ca]), cell viability, and the role of Ca-dependent pathways in T-47D human breast cancer cells. Specifically, it examined the relationship between Ca signaling and cytotoxicity in cells exposed to alantolactone, with or without the Ca chelator BAPTA-AM. The findings reveal that alantolactone (25-75 μM) increases [Ca] in a concentration-dependent manner, while concentrations of 25-100 μM induce cytotoxicity, an effect that can be reversed by BAPTA-AM pre-treatment. Removing extracellular Ca significantly inhibits Ca influx, and both SKF96365 and 2-APB, modulators of store-operated Ca channels, block the alantolactone-induced Ca entry. Additionally, in a Ca-free environment, thapsigargin, an inhibitor of the endoplasmic reticulum Ca pump, suppresses the alantolactone-induced rise in [Ca], while alantolactone reduces the [Ca] increase triggered by thapsigargin. Moreover, inhibiting phospholipase C (PLC) with U73122 abolishes the alantolactone-induced [Ca] elevation. These results suggest that alantolactone-induced cell death in T-47D cells is Ca-dependent, involving Ca entry via store-operated channels and Ca release from the endoplasmic reticulum, with PLC playing a pivotal role. Importantly, the ability of BAPTA-AM to reverse alantolactone's cytotoxic effects highlights its potential therapeutic significance in breast cancer research.