BACKGROUND Nivolumab, a programmed death-1 checkpoint inhibitor, demonstrated encouraging overall survival in uncontrolled studies in previously treated patients with advanced renal cell carcinoma. This randomized, open-label, phase 3 study compared nivolumab with everolimus in renal cell carcinoma after prior treatment. METHODS Eight hundred twenty-one patients with advanced clear-cell renal cell carcinoma previously treated with one or two antiangiogenic therapies were randomized (1:1) to receive nivolumab 3 mg/kg intravenously every 2 weeks or everolimus 10-mg tablet orally once daily. Primary end point was overall survival. Secondary end points included objective response rate and safety. RESULTS Median (95% confidence interval [CI]) overall survival was 25.0 months (21.8 to not estimable) with nivolumab and 19.6 months (17.6 to 23.1) with everolimus. The hazard ratio for risk of death with nivolumab versus everolimus was 0.73 (98.5% CI, 0.57 to 0.93; P=0.0018), meeting the predefined criterion for superiority (P≤0.0148). Objective response rate was greater with nivolumab (25%) than everolimus (5%; odds ratio 5.98; 95% CI, 3.68 to 9.72; P<0.001). Median (95% CI) progression-free survival was 4.6 months (3.7 to 5.4) with nivolumab and 4.4 months (3.7 to 5.5) with everolimus (hazard ratio, 0.88; 95% CI, 0.75 to 1.03; P=0.11). Grade 3 or 4 treatment-related adverse events occurred in 19% (nivolumab) and 37% (everolimus) of patients; most common was fatigue (3%) with nivolumab and anemia (8%) with everolimus. CONCLUSIONS Overall survival was longer and fewer grade 3 or 4 adverse events occurred for nivolumab versus everolimus in treatment-experienced patients with advanced renal cell carcinoma. ClinicalTrials.gov Identifier: NCT01668784

Mnk1 and Mnk2 are protein kinases that are directly phosphorylated and activated by extracellular signal-regulated kinase (ERK) or p38 mitogen-activated protein (MAP) kinases and implicated in the regulation of protein synthesis through their phosphorylation of eukaryotic translation initiation factor 4E (eIF4E) at Ser209. To investigate their physiological functions, we generated mice lacking the Mnk1 or Mnk2 gene or both; the resulting KO mice were viable, fertile, and developed normally. In embryonic fibroblasts prepared from Mnk1-Mnk2 DKO mice, eIF4E was not detectably phosphorylated at Ser209, even when the ERK and/or p38 MAP kinases were activated. Analysis of embryonic fibroblasts from single KO mice revealed that Mnk1 is responsible for the inducible phosphorylation of eIF4E in response to MAP kinase activation, whereas Mnk2 mainly contributes to eIF4E's basal, constitutive phosphorylation. Lipopolysaccharide (LPS)-or insulininduced upregulation of eIF4E phosphorylation in the spleen, liver, or skeletal muscle was abolished in Mnk1 ؊/؊ mice, whereas the basal eIF4E phosphorylation levels were decreased in Mnk2 ؊/؊ mice. In Mnk1-Mnk2 DKO mice, no phosphorylated eIF4E was detected in any tissue studied, even after LPS or insulin injection. However, neither general protein synthesis nor cap-dependent translation, as assayed by a bicistronic reporter assay system, was affected in Mnk-deficient embryonic fibroblasts, despite the absence of phosphorylated eIF4E. Thus, Mnk1 and Mnk2 are exclusive eIF4E kinases both in cultured fibroblasts and adult tissues, and they regulate inducible and constitutive eIF4E phosphorylation, respectively. These results strongly suggest that eIF4E phosphorylation at Ser209 is not essential for cell growth during development.Mitogen-activated protein kinases (MAPKs) are activated by various extracellular signals, such as growth factors, stresses, and cytokines, and play crucial roles in the determination of cell fate through proliferation, differentiation, survival, and apoptosis (1,5,24,38) . Three classes of MAPK families, the ERK, Jun N-terminal kinase/stress-activated protein kinase, and p38 MAPK, are differentially activated depending on the signaling context and in turn phosphorylate target proteins, which include transcription factors and protein kinases. These proteins can be common targets for subsets of MAPK proteins or specific targets for individual MAPKs. The direct downstream protein kinases, comprehensively called the MAPKactivated protein kinase (MAPKAPK) family, can be categorized into four subclasses, the Rsk, MK, Mnk, and Msk families. The Rsks (Rsk1, Rsk2, and Rsk3) are activated specifically by ERKs, whereas the MKs (MK2/MAPKAPK2, MK3/ MAPKAPK3/3pK, and MK5/PRAK) are activated mainly by p38 MAPK in vivo. In contrast, the Mnks (Mnk1 and Mnk2) and Msks (Msk1 and Msk2) are targeted in vivo by both the ERK and p38 MAPK pathways, resulting in the activation of Mnks and Msks by a broad spectrum of extracellular stimuli.Mnk1 (MAPK signal-integrating kinase 1/MAPK-int...

Genetically engineered mouse models are powerful tools for studying cancer genes and validating targets for cancer therapy. We previously used a mouse lymphoma model to demonstrate that the translation initiation factor eIF4E is a potent oncogene in vivo. Using the same model, we now show that the oncogenic activity of eIF4E correlates with its ability to activate translation and become phosphorylated on Ser 209. Furthermore, constitutively activated MNK1, an eIF4E Ser 209 kinase, promotes tumorigenesis in a manner similar to eIF4E, and a dominant-negative MNK mutant inhibits the in vivo proliferation of tumor cells driven by mutations that deregulate translation. Phosphorylated eIF4E promotes tumorigenesis primarily by suppressing apoptosis and, accordingly, the anti-apoptotic protein Mcl-1 is one target of both phospho-eIF4E and MNK1 that contributes to tumor formation. Our results provide insight into how eIF4E contributes to tumorigenesis and pinpoint a level of translational control that may be suitable for therapeutic intervention.Supplemental material is available at http://www.genesdev.org.

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Isocitrate dehydrogenase-1 (IDH1) R132 mutations occur in glioma, but their physiological significance is unknown. Here we describe the generation and characterization of brain-specific Idh1 R132H conditional knockin (KI) mice. Idh1 mutation results in hemorrhage and perinatal lethality. Surprisingly, intracellular reactive oxygen species (ROS) are attenuated in Idh1-KI brain cells despite an apparent increase in the NADP + /NADPH ratio. Idh1-KI cells also show high levels of D-2-hydroxyglutarate (D2HG) that are associated with inhibited prolyl-hydroxylation of hypoxia-inducible transcription factor-1a (Hif1a) and up-regulated Hif1a target gene transcription. Intriguingly, D2HG also blocks prolyl-hydroxylation of collagen, causing a defect in collagen protein maturation. An endoplasmic reticulum (ER) stress response induced by the accumulation of immature collagens may account for the embryonic lethality of these mutants. Importantly, D2HG-mediated impairment of collagen maturation also led to basement membrane (BM) aberrations that could play a part in glioma progression. Our study presents strong in vivo evidence that the D2HG produced by the mutant Idh1 enzyme is responsible for the above effects.

The androgen receptor (AR) can be activated in the absence of androgens by interleukin-6 (IL-6) in human prostate cancer cells. The events involved in ligand-independent activation of the AR are unknown, but have been suggested to involve phosphorylation of the AR itself or a receptor-associated protein. Steroid receptor coactivator-1 (SRC-1) has been shown to interact with the human AR and to modulate ligand-dependent AR transactivation and is regulated by phosphorylation by MAPK. To date, no one has examined the role of SRC-1 in ligand-independent activation of the AR by IL-6 or other signaling pathways known to activate the full-length receptor. This study addressed this and has revealed the following. 1) SRC-1 similarly enhanced ligand-independent activation of the AR by IL-6 to the same magnitude as that obtained via ligand-dependent activation. 2) Androgen and IL-6 stimulated the MAPK pathway. 3) MAPK was required for both ligand-dependent and ligand-independent activation of the AR. 4) Phosphorylation of SRC-1 by MAPK was required for optimal ligandindependent activation of the AR by IL-6. 5) Proteinprotein interaction between endogenous AR and SRC-1 was dependent upon treatment of LNCaP cells with IL-6 or R1881. 6) Protein-protein interaction between the AR N-terminal domain and SRC-1 was independent of MAPK. 7) Ligand-independent activation of the AR did not occur by a mechanism of overexpression of either solely wild-type SRC-1 or mutant SRC-1 that mimics its phosphorylated form.

MAP kinase-interacting kinase 1 and 2 (Mnk1 and Mnk2) are proteinserine/threonine kinases that are activated by ERK or p38 and phosphorylate eIF4E, which is involved in cap-dependent translation initiation. However, Mnk1/2 double knockout (Mnk-DKO) mice show normal cell growth and development despite an absence of eIF4E phosphorylation. Here we show that the tumorigenesis occurring in the Lck-Pten mouse model (referred to here as tPten −/− mice) can be suppressed by the loss of Mnk1/2. Phosphorylation of eIF4E was greatly enhanced in lymphomas of parental tPten −/− mice compared with lymphoid tissues of wild-type mice, but was totally absent in lymphomas of tPten −/− ; Mnk-DKO mice. Notably, stable knockdown of Mnk1 in the human glioma cell line U87MG resulted in dramatically decreased tumor formation when these cells were injected into athymic nude mice. Our data demonstrate an oncogenic role for Mnk1/2 in tumor development, and highlight these molecules as potential anticancer drug targets that could be inactivated with minimal side effects.

SUMMARY Mutations in the isocitrate dehydrogenase-1 gene (IDH1) are common drivers of acute myeloid leukemia (AML) but their mechanism is not fully understood. It is thought that IDH1 mutants act by inhibiting TET2 to alter DNA methylation, but there are significant unexplained clinical differences between IDH1- and TET2-mutant diseases. We have discovered that mice expressing endogenous mutant IDH1 have reduced numbers of hematopoietic stem cells (HSC), in contrast to Tet2 knockout (TET2-KO) mice. Mutant IDH1 downregulates the DNA damage (DD) sensor ATM by altering histone methylation, leading to impaired DNA repair, increased sensitivity to DD, and reduced HSC self-renewal, independent of TET2. ATM expression is also decreased in human IDH1-mutated AML. These findings may have implications for treatment of IDH-mutant leukemia.