Activation of store – operated Ca(2+) entry in cisplatin resistant leukemic cells after treatment with photoexcited fullerene C(60) and cisplatin

Abstract

Ca2+-regulating system in cancer cells is suggested to be remodulated particularly by reduced store-operated Ca2+ entry (SOCE) through plasma membrane in order to maintain moderately reduced cytosolic Ca2+ concentration and to avoid apoptosis. The endoplasmic reticulum (ER) Ca2+ pool content and the size of SOCE in leukemic wild type (L1210) and resistant to cisplatin (L1210R) cells in control, after treatment with either cisplatin (1 µg/ml) or photoexcited fulleren C60 (10-5 M) alone, or their combination were estimated with the use of Indo-1 AM. The SOCE in resistant to cisplatin L1210R cells was found to be lower than in the wild-type cells. After treatment with cisplatin the decrease of thapsigargin (TG)-sensitive ER Ca2+ pool with no significant increase of SOCE was observed in L1210 cells, while no changes were detected in L1210R cells. Photoexcitation of intracellular accumulated fullerene C60 in the visible range of spectrum (410-700 nm) was accompanied by increase of SOCE not only in sensitive, but in resistant cells as well. In resistant L1210R cells treated with photoexcited C60 essential effect of cisplatin on Ca2+ homeostasis became obvious: the size of SOCE proved to be higher than after treatment with photoexcited C60 alone. The data obtained allow suggesting­ the influence of photoexcited C60 not only on Ca2+-regulating system, but on those involved in controlling cisplatin entry into drug resistant cancer cells.

Keywords

• cium
• cisplatin
• drug resistance
• fullerene C(60)
• leukemic cells
• SOCE