Figure 5.

Role of Rad51 knockdown on synergy between olaparib and oncolytic herpes simplex viruses. A) MGG4 or BT74 cells transduced with lentivirus expressing Rad51- or control-shRNA were grown under puromycin selection for seven days prior to immunoblot analysis. β-actin is loading control. B) MGG4 cells transduced with shRNA-control or shRNA-Rad51 were treated with olaparib (Ola; 1 μM), MG18L (0.04 MOI), G47Δ (0.04 MOI), or the combination (O + M, O + G) for six days, and cell viability was measured by MTS assay and represented as mean ± SD. *P < .01; †P < .001; ‡P < .0001 (multiple comparisons test, Tukey) between indicated pairs. MG18L shRNA-control vs shRNA-Rad51 (P = .02) and O + G shRNA-control vs shRNA-Rad51 (P = .02). C) BT74 cells transduced with shRNA-control or shRNA-Rad51 were treated with olaparib (Ola; 10 μM), MG18L (left; M), G47Δ (right; G), or combination (O + M, O + G) at the MOIs indicated for six days, and cell viability was measured by MTS assay and represented as mean ± SD. *P < .05; †P < .001; ‡P < .0001 (multiple comparisons test, Tukey) between indicated pairs. The combination of O + G statistically significantly increased viability with shRNA-Rad51 vs shRNA-control; P = .05, .01, .02 for MOIs of .03, .1, .3, respectively. The combination of O + M statistically significantly increased viability with shRNA-Rad51 vs shRNA-control; P = .02, .0005, .02 for MOIs of 0.1, 0.3, 1, respectively. M (1 MOI, shRNA-control) vs O + M (1 MOI, shRNA-control), P = .01; M (0.1 MOI, shRNA-control) vs M (0.1 MOI, shRNA-Rad51), P = .004; and G (0.03 MOI, shRNA-control) vs G (0.03 MOI, shRNA-Rad51), P = .002. D) Rad51 shRNA abrogates synergy. Interaction of olaparib and MG18L (left) or G47Δ (right) in MGG4 transduced with shRNA-control (shcontrol) or shRNA-Rad51 (shRad51). Combination index < 1, = 1, and > 1 indicates synergistic, additive, and antagonistic interactions, respectively. All statistical tests were two-sided. Ola = olaparib.