Page 109 - 2019_12-Haematologica-web

FLT3-ITD leukemia, DOCK2 and DNA damage response
whether these cells are more sensitive to treatment with DDR inhibitors. CHK1 and WEE1 are activated in response to DNA damage and replication stress, and arrest cells in the S and G2 phases of the cell cycle. Both CHK1 and WEE1 are overexpressed in more than 50% of myeloid leukemias and are important determinants of ara-
A
C sensitivity in AML cells.42 RAD51 is one of the key fac- tors in the homology-directed DNA repair pathway and has been shown to play important roles in DNA repair in FLT3-ITD leukemic cells.43,44 MV4;11 cells with DOCK2 KD showed an increase in the percentage of apoptotic cells after treatment with the CHK1 inhibitor MK8776,
B
C
Figure 3. Exogenous expression of FLT3-ITD led to increased DNA repair activity in TF-1 cells. (A) TF-1 cells expressing FLT3-ITD exhibited increased Rac1 activity and reac- tive oxygen species (ROS) levels compared to parental TF-1 cells. (B) Quantitative reverse transcriptase polymerase chain reaction assays revealed increased expression of CHK1, WEE1, MSH2, MSH6, MLH1, and RAD51 in TF-1 cells expressing FLT3-ITD, but not in cells expressing wildtype (WT) FLT3. The levels of the transcripts were nor- malized based on that of GAPDH. To better visualize the differences in expression, the relative levels of FLT3 compared to that of TF-1-WT cells are shown, while for other genes, the relative levels of transcripts compared to those of TF-1-ITD-B cells are exhibited. (C) MTT assays revealed increased survival of FLT3-ITD-expressing TF-1 cells in the presence of ara-C (48 h). *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001. C: cells expressing control short hairpin (sh)RNA; KD: knockdown cells expressing shRNA against DOCK2.
haematologica | 2019; 104(12)
2423