MNT aids MYC-driven B lymphomagenesis by curbing MYC-induced apoptosis, primarily through suppressing BIM
Induced MNT loss in transplanted Em-Myc lymphomas extends recipient survival, making MNT a novel therapeutic target for MYC-driven tumors
Deregulated over-expression of MYC is implicated in the development and malignant progression of most (~70%) human tumors. MYC drives cell growth and proliferation but also, at high levels, promotes apoptosis. Here, we report that the proliferative capacity of MYC-driven normal and neoplastic B lymphoid cells depends on MNT, a MYC-related transcriptional repressor. Our genetic data establish that MNT synergises with MYC by suppressing MYC-driven apoptosis and that it does so primarily by reducing the level of pro-apoptotic BIM. In Em-Myc mice, which model the MYC/IGH chromosome translocation in Burkitt's lymphoma, homozygous Mnt deletion greatly reduced lymphoma incidence by enhancing apoptosis and markedly decreasing premalignant B lymphoid cell populations. Strikingly, by inducing Mnt deletion within transplanted fully-malignant Em-Myc lymphoma cells, we significantly extended transplant recipient survival. The dependency of lymphomas on MNT for survival suggests that drugs inhibiting MNT could significantly boost therapy of MYC-driven tumors by enhancing intrinsic MYC-driven apoptosis.