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Highlights • Neutrophils play important roles throughout the metastatic process. • Tumour progression and invasion are influenced by infiltrating neutrophils. • Signalling from neutrophils can enhance survival of circulating tumour cells. • Neutrophils play a key role in establishing the metastatic niche., The metastasis cascade is complex and comprises several stages including local invasion into surrounding tissue, intravasation and survival of tumour cells in the circulation, and extravasation and colonisation of a distant site. It is increasingly clear that these processes are driven not only by signals within the tumour cells, but are also profoundly influenced by stromal cells and signals in the tumour microenvironment. Amongst the many cell types within the tumour microenvironment, immune cells such as lymphocytes, macrophages and neutrophils play a prominent role in tumour development and progression. Neutrophils, however, have only recently emerged as important players, particularly in metastasis. Here we review the current evidence suggesting a multi-faceted role for neutrophils in the metastatic cascade.

KRAS-mutant colorectal cancers are resistant to therapeutics, presenting a significant problem for ∼40% of cases. Rapalogs, which inhibit mTORC1 and thus protein synthesis, are significantly less potent in KRAS-mutant colorectal cancer. Using Kras-mutant mouse models and mouse- and patient-derived organoids, we demonstrate that KRAS with G12D mutation fundamentally rewires translation to increase both bulk and mRNA-specific translation initiation. This occurs via the MNK/eIF4E pathway culminating in sustained expression of c-MYC. By genetic and small-molecule targeting of this pathway, we acutely sensitize KRASG12D models to rapamycin via suppression of c-MYC. We show that 45% of colorectal cancers have high signaling through mTORC1 and the MNKs, with this signature correlating with a 3.5-year shorter cancer-specific survival in a subset of patients. This work provides a c-MYC–dependent cotargeting strategy with remarkable potency in multiple Kras-mutant mouse models and metastatic human organoids and identifies a patient population that may benefit from its clinical application. Significance: KRAS mutation and elevated c-MYC are widespread in many tumors but remain predominantly untargetable. We find that mutant KRAS modulates translation, culminating in increased expression of c-MYC. We describe an effective strategy targeting mTORC1 and MNK in KRAS-mutant mouse and human models, pathways that are also commonly co-upregulated in colorectal cancer. This article is highlighted in the In This Issue feature, p. 995

The recurring association of specific genetic lesions with particular types of cancer is a fascinating and largely unexplained area of cancer biology. This is particularly true of clear cell renal cell carcinoma (ccRCC) where, although key mutations such as loss of VHL is an almost ubiquitous finding, there remains a conspicuous lack of targetable genetic drivers. In this study, we have identified a previously unknown protumorigenic role for the RUNX genes in this disease setting. Analysis of patient tumor biopsies together with loss-of-function studies in preclinical models established the importance of RUNX1 and RUNX2 in ccRCC. Patients with high RUNX1 (and RUNX2) expression exhibited significantly poorer clinical survival compared with patients with low expression. This was functionally relevant, as deletion of RUNX1 in ccRCC cell lines reduced tumor cell growth and viability in vitro and in vivo. Transcriptional profiling of RUNX1-CRISPR–deleted cells revealed a gene signature dominated by extracellular matrix remodeling, notably affecting STMN3, SERPINH1, and EPHRIN signaling. Finally, RUNX1 deletion in a genetic mouse model of kidney cancer improved overall survival and reduced tumor cell proliferation. In summary, these data attest to the validity of targeting a RUNX1-transcriptional program in ccRCC. Significance: These data reveal a novel unexplored oncogenic role for RUNX genes in kidney cancer and indicate that targeting the effects of RUNX transcriptional activity could be relevant for clinical intervention in ccRCC.

Different thresholds of Wnt signalling are thought to drive stem cell maintenance, regeneration, differentiation and cancer. However, the principle that oncogenic Wnt signalling could be specifically targeted remains controversial. Here we examine the requirement of BCL9/9l, constituents of the Wnt-enhanceosome, for intestinal transformation following loss of the tumour suppressor APC. Although required for Lgr5+ intestinal stem cells and regeneration, Bcl9/9l deletion has no impact upon normal intestinal homeostasis. Loss of BCL9/9l suppressed many features of acute APC loss and subsequent Wnt pathway deregulation in vivo. This resulted in a level of Wnt pathway activation that favoured tumour initiation in the proximal small intestine (SI) and blocked tumour growth in the colon. Furthermore, Bcl9/9l deletion completely abrogated β-catenin driven intestinal and hepatocellular transformation. We speculate these results support the just-right hypothesis of Wnt–driven tumour formation. Importantly, loss of BCL9/9l is particularly effective at blocking colonic tumourigenesis and mutations that most resemble those that occur in human cancer., Whether the Wnt enhanceosome’ components BCL9/9l can affect intestinal homeostasis and tumorigenesis is still unclear. Using conditional Bcl9/9l KO mice, the authors of this study show that the BCL9/9l complex is required for intestinal stem cells to drive tissue regeneration and that loss of BCL9/9l suppresses Wnt-driven transformation.

This case report describes the pathological findings of multiple congenital cardiac defects in a 2-year-old female Shetland pony with clinical signs of chronic respiratory distress. Persistent truncus arteriosus (PTA) type IV, interventricular septal defect, overriding aorta, pulmonary trunk agenesis, pulmonary arteries arising from the descending aorta, and compensatory right ventricular hypertrophy were observed.

Summary CXCR2 has been suggested to have both tumor-promoting and tumor-suppressive properties. Here we show that CXCR2 signaling is upregulated in human pancreatic cancer, predominantly in neutrophil/myeloid-derived suppressor cells, but rarely in tumor cells. Genetic ablation or inhibition of CXCR2 abrogated metastasis, but only inhibition slowed tumorigenesis. Depletion of neutrophils/myeloid-derived suppressor cells also suppressed metastasis suggesting a key role for CXCR2 in establishing and maintaining the metastatic niche. Importantly, loss or inhibition of CXCR2 improved T cell entry, and combined inhibition of CXCR2 and PD1 in mice with established disease significantly extended survival. We show that CXCR2 signaling in the myeloid compartment can promote pancreatic tumorigenesis and is required for pancreatic cancer metastasis, making it an excellent therapeutic target., Graphical Abstract, Highlights • CXCR2 signaling is upregulated in myeloid cells in human pancreatic cancer • Cxcr2 loss reduces metastasis and inhibition prolongs tumor-free survival in mice • Neutrophils/MDSCs play a key role in the establishment of the metastatic niche • CXCR2 inhibition enhances T cell entry and confers sensitivity to anti-PD1 therapy, Steele et al. show that CXCR2 is important in immune modulation of pancreatic cancer and that inhibition of CXCR2 reduces metastasis and improves response to gemcitabine and anti-PD1. Peptide inhibitor, but not germline deletion of Cxcr2, improved survival, revealing differential effects in early and late tumors.

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer-related mortality. Despite significant advances made in the treatment of other cancers, current chemotherapies offer little survival benefit in this disease. Pancreaticoduodenectomy offers patients the possibility of a cure, but most will die of recurrent or metastatic disease. Hence, preventing metastatic disease in these patients would be of significant benefit. Using principal component analysis (PCA), we identified a LOX/hypoxia signature associated with poor patient survival in resectable patients. We found that LOX expression is upregulated in metastatic tumors from Pdx1-Cre Kras G12D/+ Trp53 R172H/+ (KPC) mice and that inhibition of LOX in these mice suppressed metastasis. Mechanistically, LOX inhibition suppressed both migration and invasion of KPC cells. LOX inhibition also synergized with gemcitabine to kill tumors and significantly prolonged tumor-free survival in KPC mice with early-stage tumors. This was associated with stromal alterations, including increased vasculature and decreased fibrillar collagen, and increased infiltration of macrophages and neutrophils into tumors. Therefore, LOX inhibition is able to reverse many of the features that make PDAC inherently refractory to conventional therapies and targeting LOX could improve outcome in surgically resectable disease.

Background: Cerebral ischaemia results in a rapid and profound depletion of adenosine triphosphate (ATP), the energy currency of the cell. This depletion leads to disruption of cellular homeostasis and cell death. Early replenishment of ATP levels might therefore have a neuroprotective effect in the injured brain. We have previously shown that the ATP precursors, D-ribose and adenine (RibAde), restored the reduced ATP levels in rat brain slices to values similar to those measured in the intact rodent brain. The aim of this study was to assess whether RibAde, either alone or in combination with the xanthine oxidase inhibitor allopurinol (RibAdeAll; to further increase the availability of ATP precursors), could improve outcome in an in vivo rodent model of transient cerebral ischaemia. Methods: After 60 min occlusion of the middle cerebral artery, and upon reperfusion, rats were administered saline, RibAde, or RibAdeAll for 6 h. Baseline lesion volume was determined by diffusion-weighted MRI prior to reperfusion and final infarct volume determined by T2-weighted MRI at Day 7. Neurological function was assessed at Days 1, 3 and 7. Results: Ischaemic lesion volume decreased between Days 1 and 7: a 50% reduction was observed for the RibAdeAll group, 38% for the RibAde group and 18% in the animals that received saline. Reductions in lesion size in treatment groups were accompanied by a trend for faster functional recovery. Conclusion: These data support the potential use of ribose, adenine and allopurinol in the treatment of cerebral ischaemic injury, especially since all compounds have been used in man.

A 4-year old spayed male domestic shorthair cat was presented with a history of circling and behavioral changes. Neurologic examination showed mild proprioceptive deficits. The lesion was localized in the forebrain, and magnetic resonance imaging revealed the presence of a large midline intracranial mass extending from the frontal lobe to the tentorial region of the brain. Euthanasia was elected due to poor prognosis. Histopathologic evaluation confirmed the presence of a mass composed by sheets and aggregates of large round/polygonal cells and multinucleate cells associated with deposits of cholesterol clefts, scattered hemorrhages and hemosiderin-laden macrophages. Immunohistochemistry showed that the round/polygonal cells and multinucleate cells were strongly positive for major histocompatibility complex class II antigen, variably positive for CD18, and occasionally positive for S100. Subsets of spindle cells showing variable expression of vimentin, S100, and neuron-specific enolase were also present. The final diagnosis was cholesterol granuloma. Differential diagnosis with meningioma is discussed.

Summary The metastatic process of colorectal cancer (CRC) is not fully understood and effective therapies are lacking. We show that activation of NOTCH1 signaling in the murine intestinal epithelium leads to highly penetrant metastasis (100% metastasis; with >80% liver metastases) in KrasG12D-driven serrated cancer. Transcriptional profiling reveals that epithelial NOTCH1 signaling creates a tumor microenvironment (TME) reminiscent of poorly prognostic human CRC subtypes (CMS4 and CRIS-B), and drives metastasis through transforming growth factor (TGF) β-dependent neutrophil recruitment. Importantly, inhibition of this recruitment with clinically relevant therapeutic agents blocks metastasis. We propose that NOTCH1 signaling is key to CRC progression and should be exploited clinically., Graphical Abstract, Highlights • Epithelial NOTCH1 signaling drives metastasis in serrated CRC • Poor-prognosis CRC subtypes CMS4/CRIS-B are controlled by NOTCH1 • TGF-β-mediated neutrophil infiltration is critical for NOTCH1-driven metastasis • Neutrophil targeting provides therapeutic opportunity in metastatic CRC, In a genetically engineered mouse model, Jackstadt et al. show that NOTCH1 activation drives metastasis in KRASG12D-driven serrated colorectal cancer (CRC) through TGFβ-dependent neutrophil recruitment. Thus, targeting neutrophil recruitment is a potential therapeutic approach in metastatic CRC.

Pancreatitis is a significant clinical problem and the lack of effective therapeutic options means that treatment is often palliative rather than curative. A deeper understanding of the pathogenesis of both acute and chronic pancreatitis is necessary to develop new therapies. Pathological changes in pancreatitis are dependent on innate immune cell recruitment to the site of initial tissue damage, and on the coordination of downstream inflammatory pathways. The chemokine receptor CXCR2 drives neutrophil recruitment during inflammation, and to investigate its role in pancreatic inflammation, we induced acute and chronic pancreatitis in wild‐type and Cxcr2−/− mice. Strikingly, Cxcr2−/− mice were strongly protected from tissue damage in models of acute pancreatitis, and this could be recapitulated by neutrophil depletion or by the specific deletion of Cxcr2 from myeloid cells. The pancreata of Cxcr2−/− mice were also substantially protected from damage during chronic pancreatitis. Neutrophil depletion was less effective in this model, suggesting that CXCR2 on non‐neutrophils contributes to the development of chronic pancreatitis. Importantly, pharmacological inhibition of CXCR2 in wild‐type mice replicated the protection seen in Cxcr2−/− mice in acute and chronic models of pancreatitis. Moreover, acute pancreatic inflammation was reversible by inhibition of CXCR2. Thus, CXCR2 is critically involved in the development of acute and chronic pancreatitis in mice, and its inhibition or loss protects against pancreatic damage. CXCR2 may therefore be a viable therapeutic target in the treatment of pancreatitis. © 2015 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.