Abstract
Sodium channels of human small-cell lung cancer (SCLC) cells were examined with whole-cell and single-channel patch clamp methods. In the tumor cells from SCLC cell line NCI-H146, the majority of the voltage-gated Na+ channels are only weakly tetrodotoxin (TTX)-sensitive (K d =215 mm). With the membrane potential maintained at −60 to −80 mV, these cells produced all-or-nothing action potentials in response to depolarizing current injection (>20 pA). Similar all-ornothing spikes were also observed with anodal break excitation. Removal of external Ca2+ did not affect the action potential production, whereas 5 μm TTX or substitution of Na+ with choline abolished it. Action potentials elicited in the Ca2+-free condition were reversibly blocked by 4 mm MnCl2 due to the Mn2+-induced inhibition of voltage-dependent sodium currents (I Na). Therefore, Na+ channels, not Ca2+ channels, underlie the excitability of SCLC cells. Whole-cell I Na was maximal with step-depolarizing stimulations to 0 mV, and reversed at +45.2 mV, in accord with the predicted Nernst equilibrium potential for a Na+-selective channel. I Na evoked by depolarizing test potentials (−60 to +40 mV) exhibited a transient time course and activation/ inactivation kinetics typical of neuronal excitable membranes; the plot of the Hodgkin-Huxley parameters, m∞ and h∞, also revealed biophysical similarity between SCLC and neuronal Na+ channels. The single channel current amplitude, as measured with the inside-out patch configuration, was 1.0 pA at −20 mV with a slope conductance of 12.1 pS. The autoantibodies implicated in the Lambert-Eaton myasthenic syndrome (LES), which are known to inhibit I Ca and I Na in bovine adrenal chromaffin cells, also significantly inhibited I Na in SCLC cells. These results indicate that (i) action potentials in human SCLC cells result from the regenerative increase in voltage-gated Na+ channel conductance; (ii) fundamental characteristics of SCLC Na+ channels are the same as the classical sodium channels found in a variety of excitable cells; and (iii) in some LES patients, SCLC Na+ channels are an additional target of the pathological IgG present in the patients' sera.
Similar content being viewed by others
References
Anderson, N.E., Cunningham, J.M., Posner, J.B. 1987. Autoimmune pathogenesis of paraneoplastic neurological syndromes. Crit. Rev. Neurobiol. 3:245–299
Antoni, H., Böcker, D., Eickhorn, R. 1988. Sodium current kinetics in intact rat papillary muscle: measurements with the loose-patchclamp technique. J. Physiol. 406:199–213
Århem, P. 1980. Effects of some heavy metal ions on the ionic currents of myelinated fibres from Xenopus laevis. J. Physiol. 306:219–231
Barres, B.A., Chun, L.L.Y., Corey, D.P. 1989. Glial and neuronal forms of the voltage-dependent sodium channel: characteristics and cell-type distribution. Neuron 2:1375–1388
Cachelin, A.B., De Peyer, J.E., Kokubun, S., Reuter, H. 1983. Sodium channels in cultured cardiac cells. J. Physiol. 340:389–401
Carbone, E., Lux, H.D. 1986. Sodium channels in cultured chick dorsal root ganglion neurons. Eur. Biophys. J. 13:259–271
Carney, D.N. 1992. Biology of small-cell lung cancer. Lancet 339:843–846
Catterall, W.A. 1988. Structure and function of voltage-sensitive ion channels. Science 242:50–60
Decoursey, T.E., Chandy, K.G., Gupta, S., Cahalan, M.D. 1984. Voltage-gated K+ channels in human T-lymphocytes: a role in mitogenesis? Nature 307:466–468
Elmqvist, D., Lambert, E.H. 1968. Detailed analysis of neuromuscular transmission in a patient with the myasthenic syndrome sometimes associated with bronchogenic carcinoma. Mayo Clin. Proc. 43:689–713
Fenwick, E.M., Marty, A., Neher, E. 1982. Sodium and calcium channels in bovine chromaffin cells. J. Physiol. 331:599–635
Flamm, R.E., Birnberg, N.C., Kazcmarek, L.K. 1990. Transfection of activated rats into an excitable cell line (AtT-20) alters tetrodotoxin sensitivity of voltage-dependent sodium current. Pfluegers Arch. 416:120–125
Frelin, C., Vijverberg, H.P.M., Romey, G., Vigne, P., Lazdunski, M. 1984. Different functional states of tetrodotoxin sensitive and tetrodotoxin resistant Na+ channels occur during the in vitro development of rat skeletal muscle. Pfluegers Arch. 402:121–128
Hamill, O.P., Marty, A., Neher, E., Sakmann, B., Sigworth, F.J. 1981. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pfluegers Arch. 391:85–100
Havemann, K., Luster, W., Gropp, C., Holle, R. 1985. Peptide hormone production associated with small cell lung cancer. In: Small Cell Lung Cancer. C. Seeber editor. pp. 65–76. Springer, Heidelberg
Hodgkin, A.L., Huxley, A.F. 1952. A quantitative description of membrane current and its application to conduction and excitation in nerve. J. Physiol. 117:500–544
Isenberg, G., Klöckner, U. 1982. Isolated bovine ventricular myocytes characterization of the action potential. Pfluegers Arch. 395:19–29
Johansson, S., Rydqvist, B., Swerup, C., Heilbronn, E., & rhem, P. 1989. Action potentials of cultured human oat cells: whole-cell measurements with the patch-clamp technique. Acta Physiol. Scand. 135:573–578
Kim, Y.I., Neher, E. 1988. IgG from patients with Lambert-Eaton syndrome blocks voltage-dependent calcium channels. Science 239:405–408
Kim, Y.I., Pancrazio, J.J., Viglione, M.P. 1989. Calcium-dependent exocytosis and the type of calcium channels in a small-cell lung cancer cell line. Soc. Neurosci. Abstr. 15:824
Kirsch, G.E., Brown, A.M. 1989. Kinetic properties of single sodium channels in rat heart and rat brain. J. Gen. Physiol. 93:85–99
Lee, Y.S., Weber, M., Wurster, R.D. 1992. Roles of Ca2+ and K+ in nervous system tumor cell growth. Soc. Neurosci. Abstr. 18:1360
McCann, F.V., Pettengill, O.S., Cole, J.J., Russell, J.A.G., Sorenson, G.D. 1981. Calcium spike electrogenesis and other electrical activity in continuously cultured small cell carcinoma of the lung. Science 212:1155–1157
Ogata, N., Tatebayashi, H. 1992. Ontogenic development of the TTX-sensitive and TTX-insensitive Na+ channels in neurons of the rat dorsal root ganglia. Dev. Brain Res. 65:93–100
Pancrazio, J.J., Oie, H.K., Kim, Y.I. 1992. Voltage-sensitive calcium channels in a human small-cell lung cancer cell line. Acta Physiol. Scand. 144:463–468
Pancrazio, J.J., Viglione, M.P., Kleiman, R.J., Kim, Y.I. 1991. Verapamil-induced blockade of voltage-activated K+ current in smallcell lung cancer cells. J. Pharmacol. Exp. Ther. 257:184–191
Pancrazio, J.J., Viglione, M.P., Tabbara, I.A., Kim, Y.I. 1989. Voltagedependent ion channels in small-cell lung cancer cells. Cancer Res. 49:5901–5906
Peers, C., Lang, B., Newsom-Davis, J., Wray, D.W. 1990. Selective action of myasthenic syndrome antibodies on calcium channels in a rodent neuroblastoma x glioma cell line. J. Physiol. 421:293–308
Pietra, G.G. 1990. The pathology of carcinoma of the lung. Semin. Roentgen. 25:25–33
Plant, T.D. 1988. Na+ currents in cultured mouse pancreatic B-cells. Pfluegers Arch. 411:429–435
Roberts, A., Perera, S., Lang, B., Vincent, A., Newsom-Davis, J. 1985. Paraneoplastic myasthenic syndrome IgG inhibits 45Ca2+ influx in a human cell carcinoma line. Nature 317:737–739
Tischler, A.S., Dichter, M.A., Biales, B. 1977. Electrical excitability of oat cell carcinoma. J. Pathol. 122:153–156
Viglione, M.P., Creutz, C.E., Kim, Y.I. 1992. Lambert-Eaton syndrome: antigen-antibody interaction and calcium current inhibition in chromaffin cells. Muscle Nerve 15:1325–1333
Viglione, M.P., Kim, Y.I. 1993. Lambert-Eaton syndrome serum inhibits P-type calcium channels in small-cell lung cancer cells. Soc. Neurosci. Abstr. 19:703
Viglione, M.P., O'Shaughnessy, T.J., Kim, Y.I. 1994. P-type calcium channels in human small-cell lung cancer cells: down regulation by Lambert-Eaton syndrome antibodies. Biophys. J. 66:A422 (Abstr.)
Vincent, A., Lang, B., Newsom-Davis, J. 1989. Autoimmunity to the voltage-gated calcium channel underlies the Lambert-Eaton myasthénie syndrome, a paraneoplastic disorder. TINS 12:496–502
Weiss, R.E., Horn, R. 1986. Single-channel studies of TTX-sensitive and TTX-resistant sodium channels in developing rat muscle reveal different open channel properties. Ann. NY Acad. Sci. 479:152–161
Weiss, R.E., Sidell, N. 1991. Sodium currents during differentiation in a human neuroblastoma cell line. J. Gen. Physiol. 97:521–539
Author information
Authors and Affiliations
Additional information
Department of Biomedical Engineering
This study was supported by National Institutes of Health grant NS18607 and a research grant from the Muscular Dystrophy Association. Dr. Y.I. Kim is the recipient of a Javits Neuroscience Investigator Award from the National Institute of Neurological Disorder and Stroke.
Rights and permissions
About this article
Cite this article
Blandino, J.K.W., Viglione, M.P., Bradley, W.A. et al. Voltage-dependent sodium channels in human small-cell lung cancer cells: Role in action potentials and inhibition by lambert-eaton syndrome IgG. J. Membarin Biol. 143, 153–163 (1995). https://doi.org/10.1007/BF00234661
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00234661