Oliveira, Mariana L.Akkapeddi, PadmaRibeiro, DanielMelão, AliceBarata, João T.2022-04-122022-04-122019Adv Biol Regul. 2019 Jan;71:88-962212-4926http://hdl.handle.net/10451/52303© 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/)Interleukin 7 (IL-7) and its receptor (IL-7R, a heterodimer of IL-7Rα and γc) are essential for normal lymphoid development. In their absence, severe combined immunodeficiency occurs. By contrast, excessive IL-7/IL-7R-mediated signaling can drive lymphoid leukemia development, disease acceleration and resistance to chemotherapy. IL-7 and IL-7R activate three main pathways: STAT5, PI3K/Akt/mTOR and MEK/Erk, ultimately leading to the promotion of leukemia cell viability, cell cycle progression and growth. However, the contribution of each of these pathways towards particular functional outcomes is still not completely known and appears to differ between normal and malignant states. For example, IL-7 upregulates Bcl-2 in a PI3K/Akt/mTOR-dependent and STAT5-independent manner in T-ALL cells. This is a 'symmetric image' of what apparently happens in normal lymphoid cells, where PI3K/Akt/mTOR does not impact on Bcl-2 and regulates proliferation rather than survival. In this review, we provide an updated summary of the knowledge on IL-7/IL-7R-mediated signaling in the context of cancer, focusing mainly on T-cell acute lymphoblastic leukemia, where this axis has been more extensively studied.engB-cell acute lymphoblastic leukemiaIL-7RInterleukin 7JAK/STAT pathwayPI3K/Akt/mTOR pathwayT-ALLT-cell acute lymphoblastic leukemiajournal article10.1016/j.jbior.2018.09.0122212-4934