Triethyltin increases cytosolic Ca(2+) levels in human osteoblasts.

Area of Science:

• Toxicology
• Cell Biology
• Biochemistry

Background:

• Osteosarcoma is a primary bone cancer with significant morbidity.
• Environmental toxicants can disrupt cellular homeostasis, impacting cancer progression.
• Intracellular calcium ([Ca2+]i) signaling is crucial for cell function and proliferation.

Purpose of the Study:

• To investigate the effect of the environmental toxicant triethyltin on intracellular calcium ([Ca2+]i) levels in human osteosarcoma MG63 cells.
• To elucidate the mechanisms underlying triethyltin-induced calcium changes.

Main Methods:

• Measurement of intracellular calcium ([Ca2+]i) using fura-2 fluorescence.
• Exposure of MG63 cells to varying concentrations of triethyltin.
• Experiments conducted in the presence or absence of extracellular calcium, and with specific channel blockers and inhibitors (thapsigargin, CCCP, U73122).

Main Results:

• Triethyltin caused a rapid, concentration-dependent rise in [Ca2+]i (EC50=10 μM).
• The rise was partially dependent on extracellular calcium and involved endoplasmic reticulum calcium release, but not mitochondrial calcium or voltage-gated channels.
• Triethyltin's effect was distinct from ATP and bradykinin-induced calcium signaling pathways.

Conclusions:

• Triethyltin significantly elevates intracellular calcium in osteosarcoma cells.
• The mechanism involves both extracellular calcium influx and release from intracellular stores, likely the endoplasmic reticulum.
• These findings highlight a novel toxicological pathway for triethyltin in bone cancer cells.