Predominant expression of Kv1.3 voltage-gated K+ channel subunit in rat prostate cancer cell lines: electrophysiological, pharmacological and molecular characterisation.
Voltage-gated K+ currents expressed in two rat prostate cancer ("Dunning") cell lines of markedly different metastatic ability were characterised using electrophysiological, pharmacological and molecular approaches. Whole-cell patch-clamp recordings showed that both strongly metastatic MAT-LyLu and weakly metastatic AT-2 cell lines possessed outward (delayed-rectifier type) K+ currents, which activated at around -40 mV. From the parameters measured, several characteristics of the two cell lines were similar. However, a number of statistically significant differences were noted for MAT-LyLu versus the AT-2 cells as follows: (1) current densities were smaller; (2) the slope factor for channel activation was smaller; (3) the voltage at which current was half-inactivated, and the slope factor for channel inactivation were greater; (4) the time constants for current decay at -20 and 0 mV were smaller; and (5) the residual peak current was larger following 60 s of repetitive voltage pulses for stimulation frequencies in the range 0.05-0.2 Hz. On the other hand, the K+ currents in both cell lines showed similar pharmacological profiles. Thus, the currents were blocked by 4-aminopyridine, tetraethylammonium, verapamil, margatoxin, and charybdotoxin, with highly similar IC(50)s for given blockers. The electrophysiological and pharmacological data taken together suggested expression of voltage-gated K+ channels of the Kv1 family, expression of the Kv1.3 subunit being predominant. Western blot and RT-PCR tests both confirmed that the cells indeed expressed Kv1.3 and to a lesser extent Kv1.4 and Kv1.6 channel alpha-subunits. In view of the similarity of channel expression in the two cell lines, voltage-gated K+ channel activity may not be a primary determinant of metastatic potential in the rat model of prostate cancer, but the possible contribution of K+ channel activity to the metastatic process is discussed.
Fraser
S P
SP
Department of Biological Sciences, Imperial College of Science, Technology and Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK. s.p.fraser@ic.ac.uk
Grimes
J A
JA
Diss
J K J
JK
Stewart
D
D
Dolly
J O
JO
Djamgoz
M B A
MB
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D045744:Cell Line, Tumor / Q000502:physiology; D018999:Charybdotoxin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D051664:Kv1.3 Potassium Channel; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D011471:Prostatic Neoplasms; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012604:Scorpion Venoms; D019789:Tetraethylammonium / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; C496975:Kcna3 protein, rat; D051664:Kv1.3 Potassium Channel; D009498:Neurotoxins; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012604:Scorpion Venoms; D018999:Charybdotoxin; C077910:margatoxin; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D014700:Verapamil; D011188:Potassium