Supplementary Figure 1 PARP1 Protein Is Expressed in Phga and DIPG Patient Samples

Supplementary Figure 1 – PARP1 protein is expressed in pHGA and DIPG patient samples

A, Representative immunohistochemical staining for PARP1 in pHGA and DIPG patient samples. Pictures were taken at 10X magnification. Scale bar 100 μm.

Supplementary Figure 2 – Cell viability assay for pediatric brain tumour lines exposed to the indicated concentrations of Veliparib, Olaparib, or Niraparib.

A, MTT cell viability relative absorbance values across multiple cell lines after a 7-day incubation with Veliparib, Olaparib, or Niraparib. Boxes with an asterisk denote that an indicated concentration of PARP inhibitor significantly reduced cell viability relative vehicle treated cells. B, MTT cell viability heat map with numerical values. C, Linear regression analysis between PARP1 protein levels, relative to GAPDH, across all cell lines vs. IC50 values calculated from MTT viability assay on day 7. D, Linear regression analysis between PARP1 activity levels, relative to GAPDH, across all cell lines vs. IC50 values calculated from MTT viability assay on day 7. E, Different exposure of PARP1 Western blot in SJG2, SF188, 462, and 626 cells demonstrating variable PARP1 protein expression. *, **, ***, **** Denotes significance of p<0.05, p<0.01, p<0.001, p<0.0001, respectively. Error bars represent SEM.

Supplementary Figure 3 – Niraparib treatment increases DNA damage and decreases proliferation. A and C, Representative immunofluorescence staining for γH2AX and ki67 in SJG2, SF188, KNS42, and DIPG58 cells after a 24 hour incubation with either DMSO vehicle (V) or 5 μM Niraparib (N). DAPI was used as a nuclear counterstain. B and D, Quantification of γH2AX and ki67 in SJG2, SF188, KNS42, and DIPG58 cells. γH2AX images were taken at 63X magnification, scale bar 12 μm, ki67 images were taken at 25X magnification, scale bar 30 μm. **, ***, **** Denotes significance of p<0.01, p<0.001, p<0.0001, respectively. Error bars represent standard error of the mean.

Supplementary Figure 4 – Niraparib induces growth arrest in SJG2 and SF188 cells. A, B, MTT viability relative absorbance values of SJG2 and SF188 after being treated with an indicated concentration of Niraparib for 72h. C, Western blot for cleaved PARP1 in SJG2 and SF188 after being treated with an indicated concentration of Niraparib for 72h. D, E, Propidium Iodide DNA staining analysis in SJG2, SF188 cells, respectively, after a 72h incubation with an indicated concentration of Niraparib. *, ***, **** Denotes significance of p<0.05, p<0.001, p<0.0001, respectively. Error bars represent SEM.

Supplementary Figure 5 - Low doses of Niraparib reduce the rate of DNA repair and sensitize cells to ionizing radiation A, Several representative time points of SJG2 cells after immunofluorescent staining for γH2AX with DAPI as a counterstain after 1μM Niraparib, 2 Gy gamma radiation, or 2 Gy radiation pre-treated with 1μM Niraparib. Images were taken at indicated time points at 64X magnification.