Thimerosal-induced cytosolic Ca2+ elevation and subsequent cell death in human osteosarcoma cells.

Abstract

The effect of the oxidizing agent thimerosal on cytosolic free Ca(2+) concentration ([Ca(2+)]i) and proliferation has not been explored in human osteoblast-like cells. This study examined whether thimerosal alters Ca(2+) levels and causes cell death in MG63 human osteosarcoma cells. [Ca(2+)]i and cell death were measured using the fluorescent dyes fura-2 and WST-1, respectively. Thimerosal at concentrations above 5 microM increased [Ca(2+)]i in a concentration-dependent manner. The Ca(2+) signal was reduced by 80% by removing extracellular Ca(2+). The thimerosal-induced Ca(2+) influx was sensitive to blockade of La(3+), and dithiothreitol (50 microM) but was insensitive to nickel and several L-type Ca(2+) channel blockers. After pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor), thimerosal failed to induce [Ca(2+)]i rises. Inhibition of phospholipase C with 2 microM U73122 did not change thimerosal-induced [Ca(2+)]i rises. At concentrations of 5, 10 and 20 microM thimerosal killed 33, 55 and 100% cells, respectively. The cytotoxic effect of 5 microM thimerosal was reversed by 54% by prechelating cytosolic Ca(2+) with BAPTA. Collectively, in MG63 cells, thimerosal induced a [Ca(2+)]i rise by causing Ca(2+) release from endoplasmic reticulum stores and Ca(2+) influx from extracellular space. Furthermore, thimerosal can cause Ca(2+)-related cytotoxicity in a concentration-dependent manner.

• Authors: Hong-Tai Chang, Chung-Shin Liu, Chiang-Ting Chou, Ching-Hong Hsieh, Chih-Hung Chang, Wei-Chuan Chen, Shiuh-Inn Liu, Shu-Shong Hsu, Jin-Shyr Chen, Bang-Ping Jiann, Chung-Ren Jan
• Journal: Pharmacological research (Pharmacol Res) Vol. 52 Issue 4 Pg. 328-33 (Oct 2005) ISSN: 1043-6618 [Print] Netherlands
• PMID: 15964764 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Calcium Channel Blockers
• Chelating Agents
• Thimerosal
• Egtazic Acid
• 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
• Calcium
• Fura-2

Topics

• Bone Neoplasms
• Calcium (metabolism)
• Calcium Channel Blockers (pharmacology)
• Cell Death
• Cell Line, Tumor (drug effects)
• Cell Proliferation (drug effects)
• Chelating Agents (pharmacology)
• Egtazic Acid (analogs & derivatives, pharmacology)
• Fura-2 (metabolism)
• Humans
• Osteosarcoma
• Thimerosal (pharmacology, toxicity)