CNS neurons in adult mammals do not spontaneously regenerate axons after spinal cord injury. Preconditioning peripheral nerve injury allows the dorsal root ganglia (DRG) sensory axons to regenerate beyond the injury site by promoting expression of regenerationassociated genes. We have previously shown that peripheral nerve injury increases the number of macrophages in the DRGs and that the activated macrophages are critical to the enhancement of intrinsic regeneration capacity. The present study identifies a novel chemokine signal mediated by CCL2 that links regenerating neurons with proregenerative macrophage activation. Neutralization of CCL2 abolished the neurite outgrowth activity of conditioned medium obtained from neuron-macrophage cocultures treated with cAMP. The neuron-macrophage interactions that produced outgrowth-promoting conditioned medium required CCL2 in neurons and CCR2/CCR4 in macrophages. The conditioning effects were abolished in CCL2-deficient mice at 3 and 7 d after sciatic nerve injury, but CCL2 was dispensable for the initial growth response and upregulation of GAP-43 at the 1 d time point. Intraganglionic injection of CCL2 mimicked conditioning injury by mobilizing M2-like macrophages. Finally, overexpression of CCL2 in DRGs promoted sensory axon regeneration in a rat spinal cord injury model without harmful side effects. Our data suggest that CCL2-mediated neuron-macrophage interaction plays a critical role for amplification and maintenance of enhanced regenerative capacity by preconditioning peripheral nerve injury. Manipulation of chemokine signaling mediating neuron-macrophage interactions may represent a novel therapeutic approach to promote axon regeneration after CNS injury.

A major goal of cancer research is the identification of tumor-specific vulnerabilities that can be exploited for the development of therapies that are selectively toxic to the tumor. We show here that the transcriptional coactivators peroxisome proliferatoractivated receptor gamma coactivator 1␤ (PGC1␤) and estrogen-related receptor ␣ (ERR␣) are aberrantly expressed in human colon cell lines and tumors. With kinase suppressor of Ras 1 (KSR1) depletion as a reference standard, we used functional signature ontology (FUSION) analysis to identify the ␥1 subunit of AMP-activated protein kinase (AMPK) as an essential contributor to PGC1␤ expression and colon tumor cell survival. Subsequent analysis revealed that a subunit composition of AMPK (␣2␤2␥1) is preferred for colorectal cancer cell survival, at least in part, by stabilizing the tumor-specific expression of PGC1␤. In contrast, PGC1␤ and ERR␣ are not detectable in nontransformed human colon epithelial cells, and depletion of the AMPK␥1 subunit has no effect on their viability. These data indicate that Ras oncogenesis relies on the aberrant activation of a PGC1␤-dependent transcriptional pathway via a specific AMPK isoform.A third of all human cancers, including a substantial percentage of colorectal, lung, and pancreatic cancers, are driven by activating mutations in Ras genes. Activating K-Ras mutations are present in 35 to 40% of colon tumors and are thought to be both drivers of tumorigenesis and determinants of therapeutic regimens (1). Therapeutic disruption of Ras function has been clinically ineffective to date, but investigation of Ras pleiotropy continues to yield a diversity of downstream effectors with obligate roles in the maintenance and adaptation of Ras-driven tumors to changing environments. The Raf-MEK-extracellular signal-regulated kinase (ERK) signaling pathway is essential for the oncogenic properties of mutated K-Ras (2). However, numerous potent and specific MEK inhibitors have been developed yet have failed to demonstrate single-agent efficacy in cancer treatment (3). As a molecular scaffold of the Raf-MEK-ERK kinase cascade (4, 5), kinase suppressor of Ras 1 (KSR1) is necessary and sufficient for Ras V12 -induced tumorigenesis (4), mouse embryo fibroblast (MEF) transformation (5, 6), and pancreatic cancer growth (7) but dispensable for normal development (4). KSR1 is overexpressed in endometrial carcinoma and is required for both proliferation and anchorage-independent growth of endometrial cancer cells (8). Except for minor defects in hair follicles, KSR1 knockout mice are fertile and develop normally (4).This observation predicts that small molecules targeting KSR1 and functionally related effectors should preferentially target Rasdriven tumors while leaving normal tissue largely unaffected. More generally, this observation demonstrates that tumor cells, while under selective pressure to adapt to inhospitable environments and proliferate without constraint, will adopt strategies that, while advantageous to that singular purpose, create...

FK866 selectively kills gastric cancer cells with an EMT gene expression signature by inhibiting nicotinamide phosphoribosyltransferase in cells with NAPRT deficiency. Loss of NAPRT expression, frequently through promoter hypermethylation, is observed in many gastric tumors of the EMT subtype. FK866 might be used to treat patients with tumors of this subtype.

Modern cancer treatment employs many effective chemotherapeutic agents originally discovered from natural sources. However, a significant challenge currently confronting clinical application is balancing systemic toxicity risk with therapeutic benefit. The cyclic depsipeptide didemnin B has demonstrated impressive anti-cancer activity in preclinical models. Clinical use has been approved but is limited by sparse patient responses combined with toxicity risk and an unclear mechanism of action. From a broad-scale effort to match antineoplastic natural products to their cellular activities, we found that didemnin B selectively induces rapid and wholesale apoptosis through dual inhibition of PPT1 and EEF1A1. Furthermore, empirical discovery of a small panel of exceptional responders to didemnin B allowed generation of a regularized regression model to extract a sparse-feature genetic biomarker capable of predicting sensitivity to didemnin B. This may facilitate patient selection that could enhance and expand therapeutic application of didemnin B against neoplastic disease.

Several studies have sought systematically to identify protein subcellular locations, but an even larger task is to map which of these proteins conditionally relocates in disease (the mislocalizome). Here, we report an integrative computational framework for mapping conditional location and mislocation of proteins on a proteome-wide scale, called a conditional location predictor (CoLP). Using CoLP, we mapped the locations of over 10,000 proteins in normal human brain and in glioma. The prediction showed 0.9 accuracy using 100 location tests of 20 randomly selected proteins. Of the 10,000 proteins, over 150 have a strong likelihood of mislocation under glioma, which is striking considering that few mislocation events have been identified in this disease previously. Using immunofluorescence and Western blotting in both primary cells and tissues, we successfully experimentally confirmed 15 mislocations. The most common type of mislocation occurs between the endoplasmic reticulum and the nucleus; for example, for RNF138, TLX3, and NFRKB. In particular, we found that the gene for the mislocating protein GFRA4 had a nonsynonymous point mutation in exon 2. Moreover, redirection of GFRA4 to its normal location, the plasma membrane, led to marked reductions in phospho-STAT3 and proliferation of glioma cells. This framework has the potential to track changes in protein location in many human diseases.