Phospholipase C activator 3m3FBS reverses the synergistic toxicity of arsenic and cadmium

Background

Arsenic (As), cadmium (Cd), and lead (Pb) frequently co-occur in environmental exposures and are among the top ten toxic substances of concern. While the individual toxicity of these metals is well established, their interactive effects remain poorly understood. This study investigates the toxicological interactions among As, Cd, and Pb, with a focus on calcium (Ca²⁺)-mediated signaling mechanisms.

Methods

We evaluated the cytotoxic and apoptotic effects of individual metals and their binary/trinary mixtures in Saccharomyces cerevisiae, N2a neuroblastoma cells, and primary hippocampal neurons. Calcium signaling involvement was probed using pharmacological modulators including calmodulin inhibitor (W-7), calcineurin inhibitor (CsA), and a phospholipase C activator (3m3FBS). Cell viability was assessed by MTT and spot assays; apoptosis was analyzed using Annexin V/PI flow cytometry and DAPI/PI staining.

Results

As and Cd exhibited synergistic toxicity, while Pb antagonized their effects in trinary mixtures. Pb-mediated rescue involved calmodulin and calcineurin pathways, suggesting Ca²⁺ mimicry. Direct CaCl₂ supplementation showed only modest effects. Importantly, 3m3FBS, a PLC activator, significantly reduced apoptosis in both N2a cells and primary neurons exposed to As+Cd, partially mimicking the protective effect of Pb.

Conclusion

Our findings highlight a Ca²⁺-dependent mechanism underlying the modulation of heavy metal toxicity. While Pb attenuates As+Cd-induced neurotoxicity via calcium signaling, its own toxicity limits therapeutic utility. Activation of PLC by 3m3FBS offers a promising alternative neuroprotective strategy against heavy metal-induced damage.