Promotion of the Self-renewal Capacity of Human Leukemia Cells by Sonic Hedgehog Protein

Background: Hedgehog (Hh) signaling is involved in cancer cell growth. However, the effects of Rh stimulation on leukemia cells are unknown. Materials and Methods: The effects of recombinant sonic Hedgehog (Shh) protein on the in vitro growth of one B-lymphoma and four myeloid leukemia cell lines were examined. Results: Shh stimulation had no significant effect on the short-term growth of whole cell populations in any of the five cell lines. However, Shh promoted clonogenic cell recovery after suspension culture, suggesting promotion of leukemia stem or progenitor cell amplification in three cell lines. The lack of Hh receptors in one cell line and endogenous Shh expression in another were possible reasons for the lack of effects of Shh in these cases. Conclusion: These results suggest that Shh stimulation promotes the self-renewal capacity of leukemia stem cells in some cell lines. Inhibition of Hh signaling could represent a novel therapeutic approach in leukemia.