Figure 3

AT-MSC increased A375 proliferation and decreased apoptosis in response to cellular stress in direct cocultures in vitro. A. Proliferation of EGFP-A375 cells when mixed with increasing numbers of AT-MSC or maintained in AT-MSC conditioned low-serum medium was evaluated by relative fluorescence after 3 days. AT-MSC significantly supported tumor cell proliferation in a dose dependent manner. This effect was significantly higher in comparison to proliferation support mediated by conditioned media from the same number of AT-MSC (*p < 0.05). B. A375 cells alone or mixed with 10% AT-MSC were maintained in 0%, 0.1% or 0.5% serum-containing medium for 48 hrs and relative Caspase-3/7 activation was evaluated by luminescence caspase assay. Caspase-3/7 activity of A375 cells in 0.5% serum-containing medium was set as 100%. AT-MSC significantly decreased caspase-3/7 activation in A375 melanoma cells. C. A375 cells alone or mixed with 10% AT-MSC were treated with doxorubicin (DOX), cisplatin (cisPt) and 5-fluorouracil (5FU) for 16 hrs under serum-deprivation conditions and Caspase 3/7 activation was evaluated by luminescence caspase assay. Results were expressed as mean increase in relative luminescence units (RLU) over background luminescence in DMEM cultured cells. AT-MSC could significantly decrease extent of caspase activation induced by doxorubicin and cisplatin in A375 cells. D. A375 cells alone or mixed with CFDA-SE-AT-MSC were treated with doxorubicin, cisplatin and 5-fluorouracil for 20 hrs. Proportion of apoptotic and necrotic A375 cells was determined by Annexin V and 7-AAD, respectively. AT-MSC decreased proportion of apoptotic and necrotic A375 cells thus reducing the cytotoxicity effect mediated by doxorubicin and cisplatin (*P < 0.05).