Biopolymers and cell. 2000; 16 (6): 540 - 546

Sodium transport in the human neuroblastoma cells during early phase of differentiation with recombinant interferon-alpha 2b

O. M. Rozhmanova, E. V. Dolgaya, L. N. Stelmakh, N. Kh. Pogorelaya, V. V. Kucher, A. V. Miransky, I. S. Magura, G. Kh. Matsuka

We investigated the sodium transport induced by the recombinant interferon (IFN)-alpha 2b (laferon) in the human neuroblastoma cell line JMR 32. It has been found that IFN-alpha 2b (600 lU/ml) inhibited cell proliferation and induced morphological differentiation in 50 % of these cells by the end of the first day of incubation. This process was accompanied by an alteration in the ionic transport across the cell membrane. We have demonstrated that in undifferentiated cells, IFN-alpha 2b decreased Na influx by 20 % compared to the control cells. The membrane depolarization in these cells, induced by veratrine (200 ng/ml) in the quesence of Leiurus quinauestriatus venom (JO fig/ml), increased Na influx by 50 %. In the depolarized differentiated cells, Na influx was 3.2 times larger than in the depolarized undifferentiated cells. Tetrodotoxin (4-10~ M) completely blocked Na influx in the depolarized undifferentiated cells and reduced this influx by 50 % in the depolarized differentiated cells. These data indicate that voltage-operated tetrodotoxin-insensitive sodium channels are expressed in the neuroblastoma cells after the differentiation by IFN-alpha 2b. The Na , X -ATPase activity has decreased by half within 5 minutes of the IFN-alpha 2b addition. The enzyme activity increased up to 80 % of the control level after 22 h of exposure to IFN-alpha 2b. The in vitro data encouraged pilot studies to evaluate the in vivo antiproliferative effect of laferon.