Fig. 2: ATR inhibition selectively suppresses proliferating T-cells in humans and mouse. | Nature Communications

Fig. 2: ATR inhibition selectively suppresses proliferating T-cells in humans and mouse.

From: The ATR inhibitor ceralasertib potentiates cancer checkpoint immunotherapy by regulating the tumor microenvironment

Fig. 2

a The number of CD3+ CD8+ T-cells in MC38 tumors and spleens following treatment with vehicle or ceralasertib for 7 days (N = 9 for tumor and spleen) or 7 days-on/7 days-off (on day 15), (N = 4 for tumor, N = 5 for spleen). The number of cells for each subset was calculated per gram of tissue. Individual values, mean and SEM are shown. P values are shown on graph. NS not significant (p > 0.05). b Anti-proliferative activity of ceralasertib at indicated concentrations against in vitro stimulated/proliferating (CD3/CD28) T-cells from PBMCs isolated from different healthy donors (N = 4). Numbers represent proportion of T-cells in each cell division (P1 = 1 cell division, P2 = 2 cell divisions etc.) compared to non-proliferative cells (P0) after 6 days treatment with ceralasertib using CellTrace Violet (CTV). One way ANOVA test with correction for multiple comparisons between treated and DMSO vehicle control samples. Experiments were repeated once with 4 additional donors with the same results. c Anti-proliferative activity of ceralasertib vs vehicle (DMSO) in naïve CD8+ T-cells (nCD8+), memory CD8+ T-cells (mCD8+) and CD4+ T-cells (tCD4+). Four individual donors were tested. Experiment was repeated once with 4 additional donors with the same results. Individual results, mean and SEM are shown. d Western blot protein expression of DNA damage and cell cycle markers in unstimulated (naïve/resting) or in vitro stimulated/proliferating T-cells following 4 days vehicle (DMSO), ceralasertib, or etoposide treatments at the concentrations indicated. Representative experiment from one donor is shown. Four unique donors were profiled in parallel in one experiment showing the same results. Experiments were repeated once with the same results. e CTV proliferation assay for stimulated/proliferating T-cells after 7 days continuous or intermittent 4 days-on/3-days off ceralasertib exposure. Cells from 3 individual donors were tested. Individual results, mean and SEM are shown. Two-sided unpaired Student’s t-tests are shown as indicated. In (b, e) p values are shown as asterisk to maintain readability *p < 0.05, **p < 0.01, ***p < 0.001. Non-significant p values are not shown. Source data are provided as a Source Data file.

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