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Therapeutic potential for phenytoin: targeting Na(v)1.5 sodium channels to reduce migration and invasion in metastatic breast cancer.

Yang M, Kozminski DJ, Wold LA, Modak R, Calhoun JD, Isom LL, Brackenbury WJ - Breast Cancer Res. Treat. (2012)

Bottom Line: It may thus be an effective VGSC-blocking drug in cancer cells, which typically have depolarized membrane potentials.At a concentration within the therapeutic range used to treat epilepsy, phenytoin significantly inhibited the migration and invasion of MDA-MB-231 cells, but had no effect on weakly metastatic MCF-7 cells, which do not express Na(+) currents.We conclude that phenytoin suppresses Na(+) current in VGSC-expressing metastatic BCa cells, thus inhibiting VGSC-dependent migration and invasion.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of York, Heslington, York, YO10 5DD, UK.

ABSTRACT
Voltage-gated Na(+) channels (VGSCs) are heteromeric membrane protein complexes containing pore-forming α subunits and smaller, non-pore-forming β subunits. VGSCs are classically expressed in excitable cells, including neurons and muscle cells, where they mediate action potential firing, neurite outgrowth, pathfinding, and migration. VGSCs are also expressed in metastatic cells from a number of cancers. The Na(v)1.5 α subunit (encoded by SCN5A) is expressed in breast cancer (BCa) cell lines, where it enhances migration and invasion. We studied the expression of SCN5A in BCa array data, and tested the effect of the VGSC-blocking anticonvulsant phenytoin (5,5-diphenylhydantoin) on Na(+) current, migration, and invasion in BCa cells. SCN5A was up-regulated in BCa samples in several datasets, and was more highly expressed in samples from patients who had a recurrence, metastasis, or died within 5 years. SCN5A was also overexpressed as an outlier in a subset of samples, and associated with increased odds of developing metastasis. Phenytoin inhibited transient and persistent Na(+) current recorded from strongly metastatic MDA-MB-231 cells, and this effect was more potent at depolarized holding voltages. It may thus be an effective VGSC-blocking drug in cancer cells, which typically have depolarized membrane potentials. At a concentration within the therapeutic range used to treat epilepsy, phenytoin significantly inhibited the migration and invasion of MDA-MB-231 cells, but had no effect on weakly metastatic MCF-7 cells, which do not express Na(+) currents. We conclude that phenytoin suppresses Na(+) current in VGSC-expressing metastatic BCa cells, thus inhibiting VGSC-dependent migration and invasion. Together, our data support the hypothesis that SCN5A is up-regulated in BCa, favoring an invasive/metastatic phenotype. We therefore propose that repurposing existing VGSC-blocking therapeutic drugs should be further investigated as a potential new strategy to improve patient outcomes in metastatic BCa.

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Effect of phenytoin on migration and invasion. a Representative images of MCF-7 and MDA-MB-231 cells in a wound healing assay at 0 h, and 24 h following treatment with phenytoin (5, 50, 200 μM) or vehicle. b Migration of MCF-7 and MDA-MB-231 cells treated with phenytoin (5, 50, 200 μM) or vehicle for 24 h in wound healing assay, normalized to control (n = 135 measurements per condition). c Invasion of MCF-7 and MDA-MB-231 cells ± phenytoin (50 μM) for 48 h, normalized to control (n = 9). Data are mean ± SEM. **P < 0.01; ***P < 0.001
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Fig6: Effect of phenytoin on migration and invasion. a Representative images of MCF-7 and MDA-MB-231 cells in a wound healing assay at 0 h, and 24 h following treatment with phenytoin (5, 50, 200 μM) or vehicle. b Migration of MCF-7 and MDA-MB-231 cells treated with phenytoin (5, 50, 200 μM) or vehicle for 24 h in wound healing assay, normalized to control (n = 135 measurements per condition). c Invasion of MCF-7 and MDA-MB-231 cells ± phenytoin (50 μM) for 48 h, normalized to control (n = 9). Data are mean ± SEM. **P < 0.01; ***P < 0.001

Mentions: We next tested the effect of phenytoin on migration in a wound heal assay. Phenytoin (5–200 μM; 24 h) had no effect on the migration of MCF-7 cells (P = 0.41), but significantly reduced the migration of MDA-MB-231 cells by 27.3 ± 1.9 % at 50 μM, and 37.2 ± 1.8 % at 200 μM (P < 0.001; Fig. 6a, b). Similarly, phenytoin (50 μM; 48 h) had no effect on the invasion of MCF-7 cells (P = 0.99), but significantly reduced the invasion of MDA-MB-231 cells by 27.1 ± 3.1 % (P < 0.05; Fig. 6c). In conclusion, phenytoin significantly inhibited the migration and invasion of MDA-MB-231 cells, which express functional VGSCs.Fig. 6


Therapeutic potential for phenytoin: targeting Na(v)1.5 sodium channels to reduce migration and invasion in metastatic breast cancer.

Yang M, Kozminski DJ, Wold LA, Modak R, Calhoun JD, Isom LL, Brackenbury WJ - Breast Cancer Res. Treat. (2012)

Effect of phenytoin on migration and invasion. a Representative images of MCF-7 and MDA-MB-231 cells in a wound healing assay at 0 h, and 24 h following treatment with phenytoin (5, 50, 200 μM) or vehicle. b Migration of MCF-7 and MDA-MB-231 cells treated with phenytoin (5, 50, 200 μM) or vehicle for 24 h in wound healing assay, normalized to control (n = 135 measurements per condition). c Invasion of MCF-7 and MDA-MB-231 cells ± phenytoin (50 μM) for 48 h, normalized to control (n = 9). Data are mean ± SEM. **P < 0.01; ***P < 0.001
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Fig6: Effect of phenytoin on migration and invasion. a Representative images of MCF-7 and MDA-MB-231 cells in a wound healing assay at 0 h, and 24 h following treatment with phenytoin (5, 50, 200 μM) or vehicle. b Migration of MCF-7 and MDA-MB-231 cells treated with phenytoin (5, 50, 200 μM) or vehicle for 24 h in wound healing assay, normalized to control (n = 135 measurements per condition). c Invasion of MCF-7 and MDA-MB-231 cells ± phenytoin (50 μM) for 48 h, normalized to control (n = 9). Data are mean ± SEM. **P < 0.01; ***P < 0.001
Mentions: We next tested the effect of phenytoin on migration in a wound heal assay. Phenytoin (5–200 μM; 24 h) had no effect on the migration of MCF-7 cells (P = 0.41), but significantly reduced the migration of MDA-MB-231 cells by 27.3 ± 1.9 % at 50 μM, and 37.2 ± 1.8 % at 200 μM (P < 0.001; Fig. 6a, b). Similarly, phenytoin (50 μM; 48 h) had no effect on the invasion of MCF-7 cells (P = 0.99), but significantly reduced the invasion of MDA-MB-231 cells by 27.1 ± 3.1 % (P < 0.05; Fig. 6c). In conclusion, phenytoin significantly inhibited the migration and invasion of MDA-MB-231 cells, which express functional VGSCs.Fig. 6

Bottom Line: It may thus be an effective VGSC-blocking drug in cancer cells, which typically have depolarized membrane potentials.At a concentration within the therapeutic range used to treat epilepsy, phenytoin significantly inhibited the migration and invasion of MDA-MB-231 cells, but had no effect on weakly metastatic MCF-7 cells, which do not express Na(+) currents.We conclude that phenytoin suppresses Na(+) current in VGSC-expressing metastatic BCa cells, thus inhibiting VGSC-dependent migration and invasion.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of York, Heslington, York, YO10 5DD, UK.

ABSTRACT
Voltage-gated Na(+) channels (VGSCs) are heteromeric membrane protein complexes containing pore-forming α subunits and smaller, non-pore-forming β subunits. VGSCs are classically expressed in excitable cells, including neurons and muscle cells, where they mediate action potential firing, neurite outgrowth, pathfinding, and migration. VGSCs are also expressed in metastatic cells from a number of cancers. The Na(v)1.5 α subunit (encoded by SCN5A) is expressed in breast cancer (BCa) cell lines, where it enhances migration and invasion. We studied the expression of SCN5A in BCa array data, and tested the effect of the VGSC-blocking anticonvulsant phenytoin (5,5-diphenylhydantoin) on Na(+) current, migration, and invasion in BCa cells. SCN5A was up-regulated in BCa samples in several datasets, and was more highly expressed in samples from patients who had a recurrence, metastasis, or died within 5 years. SCN5A was also overexpressed as an outlier in a subset of samples, and associated with increased odds of developing metastasis. Phenytoin inhibited transient and persistent Na(+) current recorded from strongly metastatic MDA-MB-231 cells, and this effect was more potent at depolarized holding voltages. It may thus be an effective VGSC-blocking drug in cancer cells, which typically have depolarized membrane potentials. At a concentration within the therapeutic range used to treat epilepsy, phenytoin significantly inhibited the migration and invasion of MDA-MB-231 cells, but had no effect on weakly metastatic MCF-7 cells, which do not express Na(+) currents. We conclude that phenytoin suppresses Na(+) current in VGSC-expressing metastatic BCa cells, thus inhibiting VGSC-dependent migration and invasion. Together, our data support the hypothesis that SCN5A is up-regulated in BCa, favoring an invasive/metastatic phenotype. We therefore propose that repurposing existing VGSC-blocking therapeutic drugs should be further investigated as a potential new strategy to improve patient outcomes in metastatic BCa.

Show MeSH
Related in: MedlinePlus