Figure 1.

GSI after radiation suppressed proliferation of lung cancer. (A) Comparison of IC₅₀ values in the different treatment schedule in the MTT proliferation assay. Neither concurrent treatment schedule nor radiation after GSI I administration had a significant impact on tumour proliferation compared with GSI I alone (0 Gy). Plated cells were treated with GSI I and radiation simultaneously or radiation at 24 h after GSI I administration (n=5). Treated cells were incubated for 8 days. GSI/R: concurrent treatment schedule. GSI→R: radiation after GSI I administration. (B) Comparison of IC₅₀ in GSI I after radiation. Plated cells were treated with GSI I at varying doses at 24 h after radiation. IC₅₀ was less for combined therapy than for GSI I alone in both HCC2429 and H460 cell lines (n=5). *P<0.05. On the contrary, IC₅₀ was not different between GSI alone and combination in H1395. (C) GSI I after radiation decreased clonogenic survival in HCC2429 and H460, but not in H1395 (n=3). Cells were plated overnight and then exposed to radiation with 0 to 4 Gy as indicated. GSI I at varying doses was added at 24 h after radiation and then cells were incubated for 8 days.