Apoptosis induction by two caged xanthones and/or doxorubicin in cholangiocarcinoma (CCA) cell lines. A, Morphological changes of KKU-M156 cells after treatment with DMSO, isomorellin (0.25 μM) and/or doxorubicin (0.031 μM) for 48 h. The cells were stained with ethidium bromide and acridine orange (EB/AO) (400X). The apoptotic cells with condensed chromatin or fragmented chromatin are indicated with arrows. B, Percentage of apoptotic cells in KKU-M156 cells treated with isomorellin and/or doxorubicin at the indicated concentration for 48 h. C, Morphological changes of KKU-100 cells after treatment with DMSO, forbesione (1 μM) and/or doxorubicin (0.025 μM) for 48 h. The cells were stained with EB/AO. D, Percentage of apoptotic cells in KKU-100 cells treated with forbesione and/or doxorubicin at the indicated concentration for 48 h. Data expressed as the mean ± SE (n = 3). aP < 0.05, bP < 0.01, cP < 0.001 vs. DMSO-treated cells. Comparison between single drug treatment and combined drug treatment is indicated by #P < 0.05, ###P < 0.001.