Fig. 8. Inhibiting MCL-1 overcomes radioresistance of OSCC in vivo.

A–C CAL27R cells were treated with S63845 inhibitor (2 µM), IR (2 Gy) or a S63845/IR combination for 48 h. MTS assay was used to determine the cell viability (A), plate colony formation assay to analyze the colony formation (B) and soft agar assay to assess the anchorage-independent cell growth (C). D, E Xenograft tumors derived from CAL27R cells were treated with vehicle control (0.5% DMSO in Corn oil, 100 µL/every 2 days, i.p.), S63845 (5 mg/kg/ in 100 µL Corn oil every 2 days, i.p), IR (2 Gy/twice per week) or a S63845/IR combination when tumor volume reached 100 mm³. n = 5 mice per group. Tumor growth curves (D) were recorded and tumor sections were subjected to IHC staining of Ki67 (E). Scale bar, 25 μm. F Immunoblotting for c-caspase 3 and c-PARP expression in CAL27R cells treated with vehicle control, S63845, IR or a S63845/IR combination. All data are means ± s.e.m. ***p < 0.001.