GALNT1-Mediated Glycosylation and Activation of Sonic Hedgehog Signaling Maintains the Self-Renewal and Tumor-Initiating Capacity of Bladder Cancer Stem Cells.

The existence of bladder cancer stem cells (BCSC) has been suggested to underlie bladder tumor initiation and recurrence. Sonic Hedgehog (SHH) signaling has been implicated in promoting cancer stem cell (CSC) self-renewal and is activated in bladder cancer, but its impact on BCSC maintenance is unclear. In this study, we generated a mAb (BCMab1) against CD44(+) human bladder cancer cells that recognizes aberrantly glycosylated integrin α3β1. The combination of BCMab1 with an anti-CD44 antibody identified a BCMab1(+)CD44(+) cell subpopulation as BCSCs with stem cell-like properties. Gene expression analysis revealed that the hedgehog pathway was activated in the BCMab1(+)CD44(+) subpopulation and was required for BCSC self-renewal. Furthermore, the glycotransferase GALNT1 was highly expressed in BCMab1(+)CD44(+) cells and correlated with clinicopathologic features of bladder cancers. Mechanistically, GALNT1 mediated O-linked glycosylation of SHH to promote its activation, which was essential for the self-renewal maintenance of BCSCs and bladder tumorigenesis. Finally, intravesical instillation of GALNT1 siRNA and the SHH inhibitor cyclopamine exerted potent antitumor activity against bladder tumor growth. Taken together, our findings identify a BCSC subpopulation in human bladder tumors that appears to be responsive to the inhibition of GALNT1 and SHH signaling, and thus highlight a potential strategy for preventing the rapid recurrence typical in patients with bladder cancer.