In human pancreatic cancer cells the expression of KCNN4 channels is increased compared to non-cancer pancreatic cells and the block of these channels in a human pancreatic cancer cell line MiaPaCa-2 by TRAM-34 stops the increase in cell number during cell culture in vitro (Jäger et al. , 2004, Mol Pharm 68 :630). Therefore, we wanted to know whether this reduction in the increase in cell number is due to an arrest in the cell cycle or due to the induction of apoptosis. To distinguish these two possibilities, cells where cultered in normal FBS containing medium in the absence and presence of 3 and 10 mM TRAM-34. We determined cell numbers every 24 h for 4 days and after 4 days we observed a significant decrease in cell number in the cells treated with TRAM-34 compared to control treated cells. To estimate the amount of apoptosis induced by TRAM-34, we used FACS analysis with FITC-labelled Annexin V. This analysis showed hardly more apoptosis in the cells treated with TRAM-34 compared to untreated cells. We therefore conclude that TRAM-34 arrests MiaPaCa-2 cells in their cell cycle progression rather than induce apoptosis.

Supported by grants from the 4SC AG (Martinsried), the Wilhelm- Sander-Stiftung (2004.046.1) and the Land Baden-Württemberg (1423/74).