Characterization of Ca(2+)-inhibited potassium channels in the LNCaP human prostate cancer cell line.
Potassium plasma membrane channels have been studied in the LNCaP androgen-sensitive human prostate cancer cell line, derived from a lymph node of a subject with metastatic carcinoma of the prostate. Membrane currents were recorded by the patchclamp technique, using the cell-attached, cell-free and whole-cell mode. A voltage-dependent, non-inactivating potassium channel (delayed rectifier) was the most commonly observed ion channel in LNCaP cells. The slope conductance of K+ channels in a symmetrical 140 mM K+ gradient was 78 pS. In excised inside-out patches, the channel was inhibited by increasing the cytoplasmic Ca2+ concentration (with half-block at 0.5 microM Ca2+) over a wide range of membrane potentials. The K+ channel had a high sensitivity to tetraethylammonium (TEA), that reduced the single channel conductance with Kd of 280 +/- 27 microM. The K+ channel open probability was inhibited by alpha-dendrotoxin (DTX) (with a half-blocking concentration of approximately 5 nM) and mast cell degranulating peptide (MCDP) (with half-blocking concentration of approximately 70 nM) at all membrane potentials and with very slow reversibility. In view of the biophysical and pharmacological properties of K+ channels in LNCaP cells, it is not possible to classify these channels as one of the previously characterized types of voltage- or ligand-gated K+ channels in other cell lines.
Skryma
R
R
Laboratory of Cell Physiology, University of Lille 1, INSERM 4U007D, France. roman.skryma@univ-lille1.fr
Van Coppenolle
F
F
Dufy-Barbe
L
L
Dufy
B
B
Prevarskaya
N
N
D000230:Adenocarcinoma / Q000556:secondary*; D002118:Calcium / Q000494:pharmacology*; D018999:Charybdotoxin / Q000494:pharmacology; D004546:Elapid Venoms / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects*; D017136:Ion Transport / Q000187:drug effects; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors*; D009376:Neoplasms, Hormone-Dependent / Q000473:pathology*; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D026902:Potassium Channel Blockers; D011471:Prostatic Neoplasms / Q000473:pathology*; D011802:Quinidine / Q000494:pharmacology; D019789:Tetraethylammonium / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004546:Elapid Venoms; D009363:Neoplasm Proteins; D010455:Peptides; D026902:Potassium Channel Blockers; D018999:Charybdotoxin; C008331:mast cell degranulating peptide; D019789:Tetraethylammonium; C020273:dendrotoxin; C064719:iberiotoxin; D011802:Quinidine; D002118:Calcium