F281, synthetic agonist of the sigma-2 receptor, induces Ca2+ efflux from the endoplasmic reticulum and mitochondria in SK-N-SH cells.
We demonstrate that F281, a synthetic agonist of the sigma-2 receptor (s2R), induces a non transient increase in intracellular [Ca(2+)] ([Ca(2+)](i)) and cell death in SK-N-SH cells. Sigma receptors are classified into two subtypes, with different molecular weight and tissue distribution. While the sigma-1 receptor has been cloned, the s2r is less characterized and its physiological ligand and role need further investigation. In tumour cell lines, synthetic agonists of the s2R trigger apoptosis and modulate [Ca(2+)](i). In particular, CB-64D induces a Ca(2+) response while PB28 supresses Ca(2+) signalling. We have recently synthesized F281, by replacing the 5-methoxytetraline moiety of PB28 with a carbazole nucleus. Although this bioisosteric substitution should not affect the ligand affinity at the receptor, F281 (after 24h incubation) was more cytotoxic than PB28 (EC(50) values 65.4nM and 8.13 microM, respectively) in SK-N-SH cells. We used the fluorescent probes fura-2, rhod-2 and JC-1. F281 mobilizes Ca(2+) from mitochondria and from the endoplasmic reticulum, by opening its inositol 1,4,5-trisphosphate receptor; Ca(2+)-entry through the channels activated by store depletion was also observed. After the increase in [Ca(2+)](i) and within 10 min, we observed a sudden drop in metabolic activity and intracellular [ATP] leading to cell death.
Cassano
Giuseppe
G
Dipartimento di Fisiologia Generale ed Ambientale, Università di Bari, Bari, Italy. cassano@biologia.uniba.it
Gasparre
Giuseppe
G
Niso
Mauro
M
Contino
Marialessandra
M
Scalera
Vito
V
Colabufo
Nicola Antonio
NA
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002227:Carbazoles / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008024:Ligands; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology*; D051381:Rats; D017480:Receptors, sigma / Q000819:agonists*; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors
D002227:Carbazoles; C541818:F281 compound; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008024:Ligands; D010879:Piperazines; D017480:Receptors, sigma; C106107:sigma-2 receptor; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D002118:Calcium