Evidence of functional ryanodine receptor involved in apoptosis of prostate cancer (LNCaP) cells.
BACKGROUND
Very little is known about the functional expression and the physiological role of ryanodine receptors in nonexcitable cells, and in prostate cancer cells in particular. Nonetheless, different studies have demonstrated that calcium is a major factor involved in apoptosis. Therefore, the calcium-regulatory mechanisms, such as ryanodine-mediated calcium release, may play a substantial role in the regulation of apoptosis.


METHODS
We assessed the presence of such functional receptors in LNCaP prostate cancer cells, using fluorimetric measurements of intracellular calcium and expression assays of mRNA encoding ryanodine receptors.


RESULTS
We show here that LNCaP cells responded to caffeine, a ryanodine receptor agonist, by mobilizing calcium. Another ryanodine receptor agonist, 4-chloro-m-cresol, had a similar effect and promoted calcium release. These effects were inhibited by pretreatment with ryanodine or thapsigargin. In addition to a calcium release, caffeine was able to produce a calcium entry blocked by nickel. We used a reverse transcription-polymerase chain reaction assay to investigate the expression of ryanodine receptors in LNCaP cells. Two types of ryanodine receptor mRNAs were expressed in LNCaP cells: RyR1 and RyR2 mRNAs. Finally, we show that ryanodine receptor activation by caffeine slightly stimulates apoptosis of prostate cancer cells, and that the inhibition of these receptors by ryanodine protects the cells against apoptosis.


CONCLUSIONS
The combination of results showed that LNCaP cells, derived from a human prostate cancer, express functional RyRs able to mobilize Ca(2+) from intracellular stores and which might control apoptosis.
Mariot
P
P
Laboratoire de Physiologie Cellulaire, INSERM EPI 9938, Bâtiment SN3, USTL, Villeneuve d'Ascq, France.
Prevarskaya
N
N
Roudbaraki
M M
MM
Le Bourhis
X
X
Van Coppenolle
F
F
Vanoverberghe
K
K
Skryma
R
R
D017209:Apoptosis; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D002110:Caffeine; D002118:Calcium