Organizing co mmittee

THE CYTOTOXICAL PROPERTIES OF OLEANANE 
ALDEHYDE-Β-ENONE AGAINST DOXORUBICIN-RESISTANT 
CANCER CELLS 
 
Daria V. Eroshenko, Irina A. Tolmacheva, Mikhail A. Nazarov, and Victoria V. 
Grishko 
 
Institute of Technical Chemistry of the Ural Branch of the Russian Academy of 
Sciences, Perm Federal Scientific Centre, Russia, 614013, Perm, Academician 
Koroleva st, 3 
This study was aimed at assessing the proapoptotic potential of previously 
synthesized oleanane aldehyde-β-enone (
OA
) [1] against cancer cell lines, including 
doxorubin-resistant subclones with the P-gp overexpression. 
OA
showed equal toxicity 
to parental HBL-100 and K562 cancer cells (IC
50
0.47–0.53 µM) and their Dox-resistant 
subclones HBL-100/Dox, K562/i-S9 and K562/i-S9_Dox (IC
50
0.45−1.24 µM), as was 
determined by the MTT test [2]. 
OA
overcomes the resistance of overexpressing P-gp 
cancer cells, with 
OA
being neither a direct inhibitor, nor a competitive substrate of P-
gp [2].
The 
OA
proapoptotic effect against HBL-100 and HBL-100/Dox cells was assessed 
by means of double staining with the Annexin V/PI kit and analyzed by flow cytometry 
after 
OA
treatment at IC
50
for 16 h. The 
OA
-treatment led to an increase in the early 
and late apoptotic cell population for HBL-100 cells (23.6% vs 2.51% for untreated 
cells) and HBL-100/Dox cells (8.06% vs 2.53% for untreated cells). In addition, the cell 
cycle analysis of the HBL-100 and HBL-100/Dox cultures after 16 h 
OA
-treatment 
evinced 
OA
to cause a significant increase (up to 9%) in the sub-G0/G1 subpopulation 
with DNA-reduced cells. Fluorescence microscopy revealed the incubation of HBL-100 
and HBL-100/Dox cells with of 
OA
to be accompanied by a significant decrease in 
mitochondrial fluorescence (ΔΨm loss) and ROS generation. The release of cytochrome 
c
from mitochondria to cytosol in the HBL-100 and HBL-100/Dox cells, which was 
more remarkable in HBL-100/Dox cells, was observed after 16 h