| 12838421 |
Fraser SP, Grimes JA, Diss JK, Stewart D, Dolly JO, Djamgoz MB: Predominant expression of Kv1.3 voltage-gated K+ channel subunit in rat prostate cancer cell lines: electrophysiological, pharmacological and molecular characterisation. Pflugers Arch. 2003 Aug;446(5):559-71. Epub 2003 Jul 1.
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. |
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