Fig. 5

Combined effects of CXCL12 and CXCL11 on toxin-induced tumor cell death. Tumor cells were pretreated with CXCL12 (100 ng/ml), CXCL11 (100 ng/ml), or a combination of both chemokines for 24 h, and subsequently exposed for another 6 h (A767, A772, MDA-MB-231, DLD-1) or 12 h (A549) to either temozolomide (A767, A772; 100 μM), cisplatin (A549, DLD-1; 20 μM) or doxorubicin (MDA-MB-231, 1 μM) in the continuous presence of chemokines. Apoptotic cells were identified by FITC-labeled Annexin V and quantified by flow cytometry. Fluorescence detected in cultures treated with cytostatics in the absence of chemokines was set to 1. Data show relative changes in apoptotic cell death (+ SD) as determined in 3–6 experiments. CXCL12 and CXCL11 attenuated apoptosis of A772 cells, but stimulated death of the other tumor cells. In case of A549, A767, and MDA-MB-231 cells pro-apoptotic effects did not occur following exposure of the cells to a combination of CXCL12 and CXCL11. # p < 0.05, presence vs. absence of chemokines; § p < 0.05, double treatment vs. single treatment