Tan IIA promoted cell apoptosis and PUMA expression. (A and B) CAL27, SCC4, and SCC25 cells were treated with 2 μM Tan IIA combined with Nec-1, z-VAD-fmk, 3-MA, and CQ, respectively. (A) Cell viability was examined by MTS assay. (B) Trypan blue exclusion assay was performed to analyze the live cell population. (C and D) CAL27, SCC4, and SCC25 cells were treated with different concentrations of Tan IIA (0-5 μM) for 24h. The cell lysate was subjected to IB analysis. (E) CAL27, SCC4, and SCC25 cells were treated with 5 μM Tan IIA for indicated times. The cell lysate was subjected to IB analysis. (F-I) CAL27 and SCC4 cells were transfected with siPUMA or siControl for 24 h, followed by 5 μM Tan IIA treatment for 24h. The cell lysate was subjected to IB analysis (F). MTS analysis of cell viability (G). Colony formation ability was measured by soft agar assay (H) and plate colony formation assay (I). ***, p < 0.001.