Fig. 3

Melanosphere propagation increases tumor cell sensitivity to SU11274. a Human melanoma cells were seeded into ultra-low attachment plates in serum-free DMEM/F12 medium supplemented with B27, EGF and bFGF. M14, EGFP-A375 and Rel3 could be propagated and formed tight melanospheres. Cell line M4Beu did not form spheroids and did not proliferate under these culture conditions. Scale bar 500 μm. b–d Sensitivity of the adherent versus spheroid cultures to SU11274 was compared. Non-adherent melanoma cells M14, A375 and Rel3 were more sensitive to SU11274 inhibitor in comparison to adherent cells. Relative viability was determined by luminescent ATP-based viability assay after 5-day treatment. Values were calculated from the quadruplicates as means + SD. e Spheroid cultures were initiated from the 5000 cells seeded per well in 6-well plates with or without 1 μM SU11274. Total number of cells per well was counted 7 days later. SU11274-treatment significantly reduced a number of cells in comparison to untreated controls, *p < 0.05