Abstract
Background
WEE1 is a key tyrosine kinase involved in the cell cycle regulation with
potent anticancer effects in various cancer types including colorectal
cancer. Recent studies have focused on the potential of combinational
inhibition of Ataxia Telangiectasia and Rad-3-related protein (ATR) and WEE1
in increasing apoptosis in cancer cells. Therefore, this study investigates
the effects of inhibiting WEE1, by employing AZD1775, on colorectal cancer
cellsʼ susceptibility to VE-822-induced DNA damage and apoptosis.
Methods
SW-480 and HT-29 cells were treated with AZD1775 and VE-822, alone and in
combination. MTT assay was used to assess cell proliferation and viability.
The mRNA levels of ATR, checkpoint kinase 1 (CHK1), WEE1, ribonucleotide
reductase (RR) catalytic subunit M1 (RRM1) and RRM2 were measured by
qRT-PCR. Cellular γ-(H2A histone family member X) H2AX levels were measured
by Western blot. Analyses were conducted using ELISA to assess
8-Oxo-2ʼ-deoxyguanosine (8-oxo-dG) levels. Lactate dehydrogenase (LDH) and
ELISA death assays were used to assess apoptosis.
Results
The SW-480 and HT-29 cells have low proliferation rate when treated with
VE-822 and AZD1775. The IC50 value for VE-822 was 1.3 μM and 1.6 μM in SW480
and HT-29, respectively. Also, this value for AZD1775 in SW480 was 140 nM
and in HT-29 was 185 nM. The expression levels of ATR, CHK1, WEE1, RRM1, and
RRM2 were significantly downregulated in both cell lines treated with
combination of VE-822 and AZD1775 (P<0.05). DNA damage markers, including
γ-H2AX and 8-oxo-dG were upregulated in these cells. Simultaneous treatment
with VE-822 and AZD177 increased apoptosis capacity of both cell lines.
Conclusion
The inhibition of WEE1 via AZD1775 potentiated the anticancer effects of ATR
inhibitor, VE-822, in combating colorectal cancer via targeting DNA
damage.
Keywords
apoptosis - cancer - anticancer drugs