Fig. 5

Sialyl-glycolipid stage-specific embryonic antigen 4 (SSEA4) expression is regulated by CMP-N-acetylneuraminate-β-galactosamide-α-2,3-sialyltransferase 2 (ST3GAL2). a Small interfering RNA (siRNA)–mediated knockdown of ST3GAL2 and ST3GAL3 significantly reduced the expression of their respective target messenger RNAs (mRNAs), but not the housekeeping gene GAPDH, as measured by quantitative real-time polymerase chain reaction. Each bar represents the expression intensity normalized to the Lipofectamine reagent (Life Technologies, Carlsbad, CA, USA)-only control. b Knockdown of ST3GAL2 significantly reduced the expression of SSEA4, whereas targeting of CD133 or the close paralog ST3GAL3 did not result in a significant change of SSEA4 expression. Knockdown of CD133 expression by the respective siRNA was used as a positive control of direct targeting. Each bar represents the mean fluorescence intensity (MFI) normalized to the Lipofectamine-only control. c Expression of ST3GAL2 mRNA was measured by two Affymetrix® (Affymetrix, Santa Clara, CA, USA) probes, 217650_x_at and 229336_at, in nine tumor models and plotted against the frequency of SSEA4-positive cells as measured by flow cytometry in the respective models, which showed a significant positive correlation. ***p < 0.001; ns = not significant; n = 6