CYTOTOXIC ACTIVITY AND CELL CYCLE DISTURBANCES INDUCED BY

CYTOTOXIC ACTIVITY AND CELL CYCLE DISTURBANCES INDUCED BY
PYRIMIDOBENZIMIDAZOLES DERIVATIVES IN MCF-7 BREAST CANCER CELLS
Staub, RB1; Viau, CM1; Berwig, NA1; Amaral, SS1; Zanatta, N2; Saffi, J1
1
Department of Basic Health Sciences – Laboratory of Genetic Toxicology – UFCSPA, Porto Alegre, RS, Brazil.
2 Center for Heterocyclic Chemistry (NUQUIMHE) - UFSM, Santa Maria, RS, Brazil.
INTRODUCTION
The derivatives of pirimidobenzimidazoles (PBZ), analogous molecules of nitrogen bases present in DNA and RNA, seems
to have potential antitumor activity. In the present study, we report the biologic evaluation and molecular mechanism of a
series of PBZ against the growth of several human cancer cell lines.
RESULTS
PBZ 4, 5 and 9 promotes DNA demage by ROS generation in MCF-7 cells.
PBZ 04, 05 and 09 exerted the highest
cytotoxicity against MCF-7 cells
DCF Fluorescence
(Relative units)
100
***
***
50
***
Μ
1m
09
05
BZ
IC
H
50
2O
2
_P
BZ
_P
50
IC
IC
50
C
_P
B
on
Z0
tr o
4
l
0
After 24h of treatment, PBZs 4, 5 and 9 induce
cell cycle arrest of MCF-7 cells in G1 fase.
0
Μ
1m
09
2O
2
H
_P
50
IC
50
_P
BZ
4
BZ
Z0
B
50
S
2/
M
>4
N
G
>
Su 4N
bG
1
G
1
1
S
M
G
2/
G
1
Su
05
l
tr o
on
C
50
G
S
2/
M
>4
N
G
G
>
Su 4N
bG
1
G
1
1
S
M
2/
G
G
bSu
***
0
0
1
S
2/
M
>4
N
G
1
S
2/
M
>
Su 4N
bG
1
G
1
Su
G
b-
G
G
1
0
*
***
IC
Cell Distribution (%)
***
50
b-
Cell Distribution (%)
***
50
100
***
_P
100
100
Cell Distribution (%)
PBZ 09
γ-H2AX was induced after PBZ 04,
05 and 09 treatment and returned
to the baseline levels of untreated
cells after treatment with NAC.
100
IC
PBZ 05
PBZ 04
Fluorescence Intensity
(ΔΨm arbitrary value)
PBZ 4, 5 and 9 induce significant
mitochondrial depolarization in
MCF-7 cells.
Relaxation of the plasmid was inhibited only by PBZ 9.
MCF-7 cells were induced to late apoptosis and
necrosis after the treatment with PBZs 4, 5 and 9.
CONCLUSION
Total cells (%)
150
100
**
*
Viable Cells
Early Apoptosis
Late Apoptosis
Necrosis
***
*
*
50
09
PB
Z
04
05
PB
Z
tr
on
C
PB
Z
ol
0
PBZ 4 does not generate DNA-strand breaks,
while PBZ 5 and 9 induce signifcant DNA damage.
***
200
***
*
µΜ
09
S
M
M
IC
50
_P
80
BZ
4
BZ
_P
50
IC
50
C
_P
B
on
Z0
tr o
05
l
0
IC
DNA damage score
(abitrary units 0-400)
400
Among the 3 compounds studied,
PBZ 09 seems to present the most
promising
antitumoral
activity,
especially against MCF-7 cells. Our
results demonstrate that PBZ 09
interacts with Topo I enzyme, generates
ROS leading to DNA damage, γ-H2AX
induction, cell cycle arrest and cell
death. Therefore, further studies with
this small molecule are essential for its
safety management in breast cancer
therapy.
FINANCIAL SUPPORT