Diverse underlying proliferation response to growth factors in imatinib-treated Philadelphia chromosome-positive leukemias

Since BCR–ABL plays an essential role in the growth factor-independent proliferation of Philadelphia chromosome (Ph)+ leukemia cells, imatinib treatment of Ph+ leukemia cells inactivates signaling pathways of BCR–ABL, and subsequent addition of growth factors (GFs) could restore the signaling pathways without reactivating BCR–ABL. Here we demonstrated that non-lymphoid Ph+ leukemia cell lines responded to diverse GFs depending on their immunophenotype and gene expression of transcription factors and GF receptors, while lymphoid Ph+ leukemia cell lines restrictively responded to flit3 ligand and interleukin-7, suggesting that GF sensitivity of imatinib-treated Ph+ leukemia cells could be powerful for specifying their distinctive lineage.