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Effect of m-3M3FBS on Ca²⁺ movement in PC3 human prostate cancer cells
Jeng-Yu Tsai1, Pochuen Shieh, Daih-Huang Kuo
1Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung 81362, Taiwan, Republic of China.
Abstract:
The effect of 2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide (m-3M3FBS), a presumed phospholipase C activator, on cytosolic free Ca²⁺ concentrations ([Ca²⁺]i) in PC3 human prostate cancer cells is unclear. This study explored whether m-3M3FBS changed basal [Ca²⁺]i levels in suspended PC3 cells by using fura-2 as a Ca²⁺-sensitive fluorescent dye. M-3M3FBS at concentrations between 10-50 microM increased [Ca²⁺]i in a concentration-dependent manner. The Ca²⁺ signal was reduced by 60% by removing extracellular Ca²⁺. M-3M3FBS-induced Ca²⁺ influx was inhibited by the store-operated Ca²⁺ channel blockers nifedipine, econazole and SK&F96365, and by the phospholipase A2 inhibitor aristolochic acid. In Ca²⁺-free medium, 30 microM m-3M3FBS pretreatment greatly inhibited the [Ca²⁺]i rise induced by the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin or BHQ. Conversely, pretreatment with thapsigargin, BHQ or cyclopiazonic acid reduced the major part of m-3M3FBS-induced [Ca²⁺]i rise. Inhibition of phospholipase C with U73122 did not much alter m-3M3FBS-induced [Ca²⁺]i rise. Collectively, in PC3 cells, m-3M3FBS induced [Ca²⁺]i rises by causing phospholipase C-independent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via store-operated Ca²⁺ channels.
Insights
The compound m-3M3FBS increases calcium in prostate cancer cells by releasing it from the endoplasmic reticulum and through store-operated channels, independent of phospholipase C activation. This finding clarifies calcium signaling pathways in PC3 cells.
Area of Science:
- Cellular Biology
- Cancer Research
- Molecular Pharmacology
Background:
- The role of 2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide (m-3M3FBS) in regulating intracellular calcium (Ca²⁺) in prostate cancer cells remains largely uncharacterized.
- Phospholipase C (PLC) is often implicated in calcium signaling, but its specific involvement with m-3M3FBS is not fully understood.
Purpose of the Study:
- To investigate the effect of m-3M3FBS on cytosolic free Ca²⁺ concentrations ([Ca²⁺]i) in PC3 human prostate cancer cells.
- To elucidate the mechanisms underlying m-3M3FBS-induced calcium changes, including the involvement of extracellular calcium influx and intracellular calcium release.
Main Methods:
- Utilized fura-2, a Ca²⁺-sensitive fluorescent dye, to measure [Ca²⁺]i in suspended PC3 cells.
- Administered m-3M3FBS at varying concentrations (10-50 microM) and assessed Ca²⁺ responses under different conditions (e.g., extracellular Ca²⁺ presence/absence, pre-treatment with channel blockers or inhibitors).
- Investigated the role of store-operated Ca²⁺ channels and endoplasmic reticulum Ca²⁺ stores using specific inhibitors like nifedipine, econazole, SK&F96365, thapsigargin, BHQ, and cyclopiazonic acid, as well as PLC inhibitor U73122.
Main Results:
- m-3M3FBS significantly increased [Ca²⁺]i in a concentration-dependent manner.
- A substantial portion (60%) of the m-3M3FBS-induced Ca²⁺ signal was dependent on extracellular Ca²⁺ influx via store-operated Ca²⁺ channels, as evidenced by inhibition with specific blockers.
- m-3M3FBS induced Ca²⁺ release from the endoplasmic reticulum, which was partially inhibited by depleting intracellular stores, and conversely, depleting stores reduced the m-3M3FBS-induced Ca²⁺ rise.
- The calcium response to m-3M3FBS was largely independent of phospholipase C (PLC) activity, as demonstrated by the lack of significant effect when PLC was inhibited.
Conclusions:
- m-3M3FBS triggers an increase in cytosolic Ca²⁺ in PC3 cells through a mechanism that involves both Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via store-operated channels.
- The observed calcium signaling is independent of phospholipase C activation, suggesting alternative pathways mediate the effects of m-3M3FBS.
- These findings contribute to understanding the complex calcium dynamics in prostate cancer cells and the specific actions of m-3M3FBS.
