Forskolin activated currents in wild type and vincristine resistant K562 cells.

ASSEF Y., CAVARRA S., DAMIANO A., ZOTTA E., IBARRA C., KOTSIAS BA.

Bariloche, Argentina

Congreso; XXXII Reunión Anual de la Sociedad Argentina de Biofísica; 2003

Sociedad Argentina de Biofísica

The cell line K562 obtained from a chronic myeloid leukemia express integral membrane proteins such as CFTR (cystic fibrosis transmembrane regulator) and MDR1 (multidrug resistance). We studied with patch clamp and RT-PCR techniques, the relationship between ion currents and the pattern of expression of these proteins, in wild type (K562WT) and vincristine resistant (K562vinc) cell lines. The amplified products in K562WT showed two bands of 300 bp and 170 bp corresponding to CFTR and MDR1, respectively. These two bands were of smaller and greater intensity in K562vinc cells. In the whole cell configuration, forskoline (20 uM), an activator of adenylate cyclase, added to the extracelular side turned on an outward current in both cell lines, 8 out of 10 experiments in K562WT and 5 out of 9 in K562vinc. The cAMP-activated current was blocked by diphenylamine-2-carboxylate (DPC, 0.5 mM) added to the bath. Normalized current (I/Imax) at 80 mV were: 3.92±0.95 and 2.69±0.56 for forskoline and DPC in K562WT, respectively. In K562vinc the currents were: 9.62±4.81 and 4.56±2.14 for forskoline and DPC, respectively. The presence of an outward cAMP-activated current blocked by DPC in both cell lines suggest that these currents are not altered in spite of the different pattern of expression of CFTR and MDR1.