TGF-β signaling causes ALL quiescence

Interactions of tumor cells with their niches may cause cancer growth, survival and therapy resistance. Signaling by members of the TGF-β superfamily has mainly been studied in the context of solid tumors and quiescent hematopoietic stem cells. In order to investigate the mechanisms mediating dormancy of residual acute lymphoblastic leukemia (ALL) in the bone marrow niche, we first examined the effect of TGF-β on ALL cell proliferation in vitro. Treatment of cell lines carrying TEL-AML1 and E2A-PBX1 fusions with TGF-β lead to an exit of the cell cycle as evidenced by propidium iodine, BrdU and Ki-67-stainings. I…