Can't kick that oncogene habit

One of the most exciting developments in recent cancer treatment has been the move away from crude cytotoxic agents toward drugs that inhibit specific targets in specific cellular pathways. One assumption of this strategy is that maintenance of human cancers is dependent upon a limited cadre of therapeutically tractable oncogenic lesions. In this issue of Cancer Cell, an intriguing paper from Sharma et al. endorses this approach by showing that evolution appears to be working for us. They show that an innate asymmetry in the dynamics of intracellular signaling biases pathway inhibition in favor of cell death. This bias may significantly potentiate targeted cancer therapies

Nursing some sense out of Myc

Data recently published in BMC Biology provide insights into the normal physiological function of c-myc in the development and regeneration of the mammary gland and indicate a key role in epithelial cell proliferation, elaboration of ductal alveoli, and the biosynthetic capacity and milk production of the mature organ

Bcl-xL gain of function and p19ARF loss of function cooperate oncogenically with Myc in vivo by distinct mechanisms

SummaryOverexpression of Bcl-xL, loss of p19ARF, and loss of p53 all accelerate Myc oncogenesis. All three lesions are implicated in suppressing Myc-induced apoptosis, suggesting that this is a common mechanism by which they synergize with Myc. However, using an acutely switchable model of Myc-induced tumorigenesis, we demonstrate that each lesion cooperates with Myc in vivo by a distinct mechanism. While Bcl-xL blocks Myc-induced apoptosis, inactivation of p19ARF enhances it. However, this increase in apoptosis is matched by increased Myc-induced proliferation. p53 inactivation shares features of both lesions, partially suppressing apoptosis while augmenting proliferation. Bcl-xL and p19ARF loss together synergize to further accelerate Myc oncogenesis. Thus, differing lesions cooperate oncogenically with Myc by discrete mechanisms that can themselves synergize with each other

Myc Cooperates with Ras by Programming Inflammation and Immune Suppression.

The two oncogenes KRas and Myc cooperate to drive tumorigenesis, but the mechanism underlying this remains unclear. In a mouse lung model of KRasG12D-driven adenomas, we find that co-activation of Myc drives the immediate transition to highly proliferative and invasive adenocarcinomas marked by highly inflammatory, angiogenic, and immune-suppressed stroma. We identify epithelial-derived signaling molecules CCL9 and IL-23 as the principal instructing signals for stromal reprogramming. CCL9 mediates recruitment of macrophages, angiogenesis, and PD-L1-dependent expulsion of T and B cells. IL-23 orchestrates exclusion of adaptive T and B cells and innate immune NK cells. Co-blockade of both CCL9 and IL-23 abrogates Myc-induced tumor progression. Subsequent deactivation of Myc in established adenocarcinomas triggers immediate reversal of all stromal changes and tumor regression, which are independent of CD4+CD8+ T cells but substantially dependent on returning NK cells. We show that Myc extensively programs an immune suppressive stroma that is obligatory for tumor progression

Cell Cycle Phase-Specific Surface Expression of Nerve Growth Factor Receptors TrkA and p75NTR

[EN]Expression of the nerve growth factor (NGF) receptors TrkA and p75NTR was found to vary at the surface of PC12 cells in a cell cycle phase-specific manner. This was evidenced by using flow cytometric and microscopic analysis of cell populations labeled with antibodies to the extracellular domains of both receptors. Differential expression of these receptors also was evidenced by biotinylation of surface proteins and Western analysis, using antibodies specific for the extracellular domains of TrkA and p75NTR. TrkA is expressed most strongly at the cell surface in M and early G1 phases, whereas p75NTR is expressed mainly in late G1, S, and G2 phases. This expression reflects the molecular and cellular responses to NGF in specific phases of the cell cycle; in the G1 phase NGF elicits both the anti-mitogenic effect, i.e., inhibition of the G1 to S transition, and the differentiation response whereas a survival effect is provoked elsewhere in the cell cycle. A model is proposed relating these responses to the surface expression of the two receptors. These observations open the way for novel approaches to the investigation of the mechanism of NGF signal transduction

Lipid Remodeling in Hepatocyte Proliferation and Hepatocellular Carcinoma.

BACKGROUND AND AIMS: Hepatocytes undergo profound metabolic rewiring when primed to proliferate during compensatory regeneration and in hepatocellular carcinoma (HCC). However, the metabolic control of these processes is not fully understood. In order to capture the metabolic signature of proliferating hepatocytes, we applied state-of-the-art systems biology approaches to models of liver regeneration, pharmacologically and genetically activated cell proliferation, and HCC. APPROACH AND RESULTS: Integrating metabolomics, lipidomics, and transcriptomics, we link changes in the lipidome of proliferating hepatocytes to altered metabolic pathways including lipogenesis, fatty acid desaturation, and generation of phosphatidylcholine (PC). We confirm this altered lipid signature in human HCC and show a positive correlation of monounsaturated PC with hallmarks of cell proliferation and hepatic carcinogenesis. CONCLUSIONS: Overall, we demonstrate that specific lipid metabolic pathways are coherently altered when hepatocytes switch to proliferation. These represent a source of targets for the development of therapeutic strategies and prognostic biomarkers of HCC.J.L.G., Z.H. and M.V. are funded by the Medical Research Council (MRC grant MC UP A90 1006 & MC PC 13030). J.L.G. and Z.H. are supported by the Imperial Biomedical Research Centre, NIHR. M.A., A.V-P., F.O., Q.M.A. and M.V. are members of the EPoS consortium, which is funded by the Horizon 2020 Framework Program of the European Union under Grant Agreement 634413. F.O. is supported by MRC program grants (MR/K0019494/1 and MR/R023026/1). J.L is supported by MRC PhD studentship and a CRUK program grant (C18342/A23390). M.V. and A.V-P. are supported by MRC MDU and MRC DMC (MC UU 12012/2). Q.M.A. received additional research support from The Liver Research Trust and is a Newcastle NIHR Biomedical Research Centre investigator. M.A., M.V., A.V-P. and J.L.G. received research support from the Evelyn Trust and the NIHR Cambridge Biomedical Research Centre (Gastroenterology Theme)

Myc inhibition is effective against glioma and reveals a role for Myc in proficient mitosis.

Gliomas are the most common primary tumours affecting the adult central nervous system and respond poorly to standard therapy. Myc is causally implicated in most human tumours and the majority of glioblastomas have elevated Myc levels. Using the Myc dominant negative Omomyc, we previously showed that Myc inhibition is a promising strategy for cancer therapy. Here, we preclinically validate Myc inhibition as a therapeutic strategy in mouse and human glioma, using a mouse model of spontaneous multifocal invasive astrocytoma and its derived neuroprogenitors, human glioblastoma cell lines, and patient-derived tumours both in vitro and in orthotopic xenografts. Across all these experimental models we find that Myc inhibition reduces proliferation, increases apoptosis and remarkably, elicits the formation of multinucleated cells that then arrest or die by mitotic catastrophe, revealing a new role for Myc in the proficient division of glioma cells