Effect of thapsigargin on Ca²⁺fluxes and viability in human prostate cancer cells

Abstract

Effect of the carcinogen thapsigargin on human prostate cancer cells is unclear. This study examined if thapsigargin altered basal [Ca²⁺](i) levels in suspended PC3 human prostate cancer cells by using fura-2 as a Ca²⁺-sensitive fluorescent probe. Thapsigargin at concentrations between 10 nM and 10 µM increased [Ca²⁺](i) in a concentration-dependent fashion. The Ca²⁺ signal was reduced partly by removing extracellular Ca²⁺ indicating that Ca²⁺ entry and release both contributed to the [Ca²⁺](i) rise. This Ca²⁺ influx was inhibited by suppression of phospholipase A2, but not by inhibition of store-operated Ca²⁺ channels or by modulation of protein kinase C activity. In Ca²⁺-free medium, pretreatment with the endoplasmic reticulum Ca²⁺ pump inhibitor 2,5-di-(t-butyl)-1,4-hydroquinone (BHQ) nearly abolished thapsigargin-induced Ca²⁺ release. Conversely, pretreatment with thapsigargin greatly reduced BHQ-induced [Ca²⁺](i) rise, suggesting that thapsigargin released Ca²⁺ from the endoplasmic reticulum. Inhibition of phospholipase C did not change thapsigargin-induced [Ca²⁺](i) rise. At concentrations of 1-10 µM, thapsigargin induced cell death that was partly reversed by chelation of Ca²⁺ with BAPTA/AM. Annexin V/propidium iodide staining data suggest that apoptosis was partly responsible for thapsigargin-induced cell death. Together, in PC3 human prostate cancer cells, thapsigargin induced [Ca²⁺](i) rises by causing phospholipase C-independent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via phospholipase A2-sensitive Ca²⁺ channels. Thapsigargin also induced cell death via Ca²⁺-dependent pathways and Ca²⁺-independent apoptotic pathways.

CHOP and caspase 3 induction underlie glioblastoma cell death in response to endoplasmic reticulum stress

“…Taken together, the time course data presented here suggest that the overall inhibitory effect of thapsigargin and tunicamycin was due to glioblastoma cell death. These results are similar to those from other studies on several types of human cancer that also demonstrated that thapsigargin (18)(19)(20)(21) and tunicamycin (22)(23)(24) promoted tumor cell death.…”

“…To this end, in this study, we demonstrate that two endoplasmic reticulum stress inducers, thapsigargin and tunicamycin, promote glioblastoma cell death. Our findings are consistent with those from previous studies on several human cancers that also showed that thapsigargin (prostate, breast, leukemia, and melanoma) (18)(19)(20)30,32) and tunicamycin (neuroblastoma and melanoma) induced tumor cell death (24,33).…”

Anti-Cancer Agents in Proliferation and Cell Death: The Calcium Connection

“…Huang et al identified a [Ca 2+ ] i -dependent apoptotic mechanism in PC3 human prostate cancer cells exposed to thapsigargin (1–10 µM). Here, the rise in [Ca 2+ ] i was attributed to both Ca 2+ -influx from extracellular environment and depletion of ER stores [128]. Combination treatment with TRAIL (70 and 35 ng/mL) and thapsigargin (0.3 and 0.6 μM) induced apoptosis and inhibited migration, invasion, and adhesion of ESCC cell lines (esophageal squamous cell carcinoma), demonstrating that this combination induces both apoptosis and inhibits metastasis [129].…”

Pink1 protects cortical neurons from thapsigargin-induced oxidative stress and neuronal apoptosis

“…In the present paper, to further identify the role of Pink1 in neuronal protections against oxidative stress and apoptosis, we investigated the expression alternations of Pink1 under oxidative conditions and whether altered Pink1 expression affected neuron survival. Thapsigargin is a specific irreversible inhibitor of endoplasmic reticulum (ER) calcium-ATPase, which leads ectopic calcium entry and causes oxidative stress and apoptosis [ 14 , 15 ]. We found that thapsigargin could lead to dramatic neuronal apoptosis by promoting oxidative stress in neurons and causes lipid peroxidations and protein oxidative carbonylations.…”