Malignant human gliomas express an amiloride-sensitive Na+ conductance.
Human astrocytoma cells were studied using whole cell patch-clamp recording. An inward, amiloride-sensitive Na+ current was identified in four continuous cell lines originally derived from human glioblastoma cells (CH235, CRT, SKMG-1, and U251-MG) and in three primary cultures of cells obtained from glioblastoma multiforme tumors (up to 4 passages). In addition, cells freshly isolated from a resected medulloblastoma tumor displayed this same characteristic inward current. In contrast, amiloride-sensitive currents were not observed in normal human astrocytes, low-grade astrocytomas, or juvenile pilocytic astrocytomas. The only amiloride-sensitive Na+ channels thus far molecularly identified in brain are the brain Na+ channels (BNaCs). RT-PCR analyses demonstrated the presence of mRNA for either BNaC1 or BNaC2 in these tumors and in normal astrocytes. These results indicate that the functional expression of amiloride-sensitive Na+ currents is a characteristic feature of malignant brain tumor cells and that this pathway may be a potentially useful target for therapeutic intervention.[1]References
- Malignant human gliomas express an amiloride-sensitive Na+ conductance. Bubien, J.K., Keeton, D.A., Fuller, C.M., Gillespie, G.Y., Reddy, A.T., Mapstone, T.B., Benos, D.J. Am. J. Physiol. (1999) [Pubmed]
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