Fig. 2. Knockout of INPP4B in A549 cells leads to sensitization to IR irradiation and PARP inhibitor olaparib.
a Under normal culture condition, knockout of INPP4B does not affect cell proliferation. Cell growth rates were measured and calculated from three independent MTT assays. b The cell survival rate was decreased in Crispr-INPP4B cells following IR. The indicated cell lines were seeded into 3.5 cm plates at 3 × 105/plate. After one day of culture, cells were irradiated with 20 Gy of IR, survival cells were counted on day 3 post IR, the average survival rates were normalized to the untreated cells immediately prior to IR irradiation and plotted in b. Data were presented as average survival rates ± SD from 3 independent experiments. *p < 0.05 indicates a significant difference of cell survival between CTL and Crispr-INPP4B cells by one-way ANOVA test. c DNA repair inhibitor PARP enhanced the IR sensitivity of INPP4B knockout cells. The three cell lines used in b were pretreated with 0.5 μM olaprib for 4 h and subjected to 20 Gy of IR. Survival cells were counted on day 3. d Cells on day 3 post IR were trypsin digested and harvested for Annexin V-FITC staining. Cells were analyzed by fluorescence activated cell sorting shown in d, and the average percentage of each group of apoptotic cells from 3 independent IR treatments was plotted in e. **(p < 0.01 by Student’s t test) indicates a significant survival difference between CTL and Crispr-INPP4B cells.