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Ion channel phenotype of melanoma cell lines
D H Allen1, A Lepple-Wienhues, M D Cahalan
1Department of Physiology and Biophysics, UC Irvine, Irvine CA 92717, USA.
Abstract:
Melanoma cells are transformed melanocytes of neural crest origin. K+ channel blockers have been reported to inhibit melanoma cell proliferation. We used whole-cell recording to characterize ion channels in four different human melanoma cell lines (C8161, C832C, C8146, and SK28). Protocols were used to identify voltage-gated (KV), Ca2+-activated (KCa), and inwardly rectifying (KIR) K+ channels; swelling-sensitive Cl- channels (Clswell); voltage-gated Ca2+ channels (CaV) and Ca2+ channels activated by depletion of intracellular Ca2+ stores (CRAC); and voltage-gated Na+ channels (NaV). The presence of Ca2+ channels activated by intracellular store depletion was further tested using thapsigargin to elicit a rise in [Ca2+]i. The expression of K+ channels varied widely between different cell lines and was also influenced by culture conditions. KIR channels were found in all cell lines, but with varying abundance. Whole-cell conductance levels for KIR differed between C8161 (100 pS/pF) and SK28 (360 pS/pF). KCa channels in C8161 cells were blocked by 10 nm apamin, but were unaffected by charybdotoxin (CTX). KCa channels in C8146 and SK28 cells were sensitive to CTX (Kd = 4 nm), but were unaffected by apamin. KV channels, found only in C8146 cells, activated at approximately -20 mV and showed use dependence. All melanoma lines tested expressed CRAC channels and a novel Clswell channel. Clswell current developed at 30 pS/sec when the cells were bathed in 80% Ringer solution, and was strongly outwardly rectifying (4:1 in symmetrical Cl-). We conclude that different melanoma cell lines express a diversity of ion channel types.
Insights
Ion channel expression varies significantly across human melanoma cell lines. Understanding these diverse ion channel profiles, including K+, Ca2+, and Cl- channels, is crucial for melanoma research.
Area of Science:
- Oncology
- Molecular Biology
- Biophysics
Background:
- Melanoma cells originate from neural crest-derived melanocytes.
- Inhibition of melanoma cell proliferation by K+ channel blockers has been previously reported.
Purpose of the Study:
- To characterize the ion channel expression profiles in four human melanoma cell lines.
- To investigate the diversity of ion channel types, including K+, Ca2+, and Cl- channels, across different melanoma cell lines.
Main Methods:
- Whole-cell electrophysiological recordings were employed.
- Protocols were designed to identify voltage-gated (KV), Ca2+-activated (KCa), inwardly rectifying (KIR) K+ channels, swelling-sensitive Cl- channels (Clswell), voltage-gated Ca2+ channels (CaV), Ca2+ release-activated channels (CRAC), and voltage-gated Na+ channels (NaV).
- Thapsigargin was used to confirm the presence of CRAC channels by inducing intracellular Ca2+ release.
Main Results:
- K+ channel expression varied widely among cell lines and was influenced by culture conditions.
- Inwardly rectifying (KIR) K+ channels were present in all cell lines, with differing abundance and conductance.
- Ca2+-activated (KCa) channels showed differential sensitivity to apamin and charybdotoxin (CTX) across cell lines.
- KV channels were identified only in the C8146 cell line.
- All tested melanoma lines expressed CRAC channels and a novel Clswell channel with strong outward rectification.
Conclusions:
- Human melanoma cell lines exhibit a diverse repertoire of ion channel types.
- The specific ion channel expression profile differs significantly between melanoma cell lines.
- This heterogeneity in ion channel expression may have implications for melanoma biology and therapeutic strategies.