XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Posters
40.
MCL-1 as a rEGULaTOr of aPOPTOSIS IN CML CELL LINE aND
PErIPHEral BLOOD MONONUCLEar CELLS
Barbora Brodská, Petra Otevřelová and Aleš Holoubek
Institute of Hematology and Blood Transfusion, U Nemocnice 1,
128 20 Prague 2, Czech Republic
Mcl-1 is a Bcl-2 family protein which can act as an apical molecule in apoptosis control,
promoting cell survival by interfering at an early stage in a cascade of events leading to
release of cytochrome c from mitochondria. Mcl-1 has a short half life and is a highly
regulated protein. We investigated changes in the expression of this protein during
combined treatment with demethylating agent decitabine (DAC) and histone deacetylase
inhibitor SAHA (Vorinostat). These drugs represent epigenetic forces regulating
gene and protein expression in cells, affecting cell cycle and cell death. In our experiments,
DAC alone causes substantial increase of p21WAF1 expression, higher levels of
proteins p53 and Puma were also detected, but the viability of the cells, as measured
by MTT test, decreased only minimally, and we did not detect any remarkable apoptotic
effect. While in CML-T1 cells we observed a slight decrease in Mcl-1 expression and
PARP fragmentation, none of these effects have been found in lymphocytes. Addition
of SAHA simultaneously with DAC supressed DAC-induced p21WAF1 up-regulation and
substantial down-regulation of Mcl-1 protein expression together with mitochondrial
membrane (MM) depolarization and PARP fragmentation was also detected. The extent
of MM depolarization and the cell viability decrease observed in both CML-T1 cells and
PBMC after DAC+SAHA treatment implies that this combination has a synergistic effect
on apoptosis and Mcl-1 seems to play a crucial role in this process.
Acknowledgement: This work was supported by the grants IGA NS 9637-4 and IGA
MZOUHKT2005 from the MHCR.
158 XXII. Biochemistry Congress, Martin