REV1 is implicated in the development of carcinogen-induced lung cancer.

The somatic mutation hypothesis of cancer predicts that reducing the frequency of mutations induced by carcinogens will reduce the incidence of cancer. To examine this, we developed an antimutator strategy based on the manipulation of the level of a protein required for mutagenic bypass of DNA damage induced by the ubiquitous carcinogen benzo[a]pyrene. The expression of this protein, REV1, was reduced in mouse cells using a vector encoding a gene-specific targeting ribozyme. In the latter cells, mutagenesis induced by the activated form of benzo[a]pyrene was reduced by >90%. To examine if REV1 transcripts could be lowered in vivo, the plasmid was complexed with polyethyleneimine, a nonviral cationic polymer, and delivered to the lung via aerosol. The endogenous REV1 transcript in the bronchial epithelium as determined by quantitative real-time PCR in laser capture microdissected cells was reduced by 60%. There was a significant decrease in the multiplicity of carcinogen-induced lung tumors from 6.4 to 3.7 tumors per mouse. Additionally, REV1 inhibition completely abolished tumor formation in 27% of the carcinogen-exposed mice. These data support the central role of the translesion synthesis pathway in the development of lung cancer. Further, the selective modulation of members of this pathway presents novel potential targets for cancer prevention. The somatic mutation hypothesis of cancer predicts that the frequency of cancers will also be reduced.

Mast Cell-Dependent CD8+ T-cell Recruitment Mediates Immune Surveillance of Intestinal Tumors in ApcMin/+ Mice.

The presence of mast cells in some human colorectal cancers is a positive prognostic factor, but the basis for this association is incompletely understood. Here, we found that mice with a heterozygous mutation in the adenomatous polyposis coli gene (ApcMin/+) displayed reduced intestinal tumor burdens and increased survival in a chemokine decoy receptor, ACKR2-null background, which led to discovery of a critical role for mast cells in tumor defense. ACKR2-/-ApcMin/+ tumors showed increased infiltration of mast cells, their survival advantage was lost in mast cell-deficient ACKR2-/-SA-/-ApcMin/+ mice as the tumors grew rapidly, and adoptive transfer of mast cells restored control of tumor growth. Mast cells from ACKR2-/- mice showed elevated CCR2 and CCR5 expression and were also efficient in antigen presentation and activation of CD8+ T cells. Mast cell-derived leukotriene B4 (LTB4) was found to be required for CD8+ T lymphocyte recruitment, as mice lacking the LTB4 receptor (ACKR2-/-BLT1-/-ApcMin/+) were highly susceptible to intestinal tumor-induced mortality. Taken together, these data demonstrate that chemokine-mediated recruitment of mast cells is essential for initiating LTB4/BLT1-regulated CD8+ T-cell homing and generation of effective antitumor immunity against intestinal tumors. We speculate that the pathway reported here underlies the positive prognostic significance of mast cells in selected human tumors. Cancer Immunol Res; 6(3); 332-47. ©2018 AACR.

A phase I clinical trial of hepatic arterial infusion of oxaliplatin and oral capecitabine, with or without intravenous bevacizumab, in patients with advanced cancer and predominant liver involvement.

BACKGROUND: We investigated hepatic arterial infusion (HAI) oxaliplatin combined with capecitabine +/- bevacizumab in advanced cancer with predominant liver involvement. METHODS: Patients received HAI oxaliplatin (140 mg/m2) and escalating doses of capecitabine (500, 750, and 1000 mg/m2), with (Group 1) or without (Group 2) bevacizumab (10 mg/kg IV). A 3 + 3 dose design was used, followed by an expansion phase. RESULTS: From 9/2009 to 2/2014, 61 patients (34 men, 27 women) were enrolled (Group 1 = 44; Group 2 = 17). Patients were treated in Group 2 if they had contraindications to bevacizumab (n = 13) or if there was no opening in Group 1 (n = 4). The median age was 60 years (range, 20-88). The most common cancers were colorectal (22 patients), liver (12), pancreatic (7), breast (4), and biliary tract (4). The median number of prior therapies was 3 (range, 1-12); 32 (53%) patients had received oxaliplatin. The dose-limiting toxicity was Grade 3 diarrhea and occurred in 2 patients receiving 1000 mg/m2 capecitabine. The maximum tolerated dose was HAI oxaliplatin 140 mg/m2, capecitabine 750 mg/m2, and bevacizumab 10 mg/kg. The most common toxicities were nausea/vomiting, anemia, thrombocytopenia, neutropenia, and hypomagnesemia. The rates of partial response and stable disease ≥ 4 months were 22% and 39% (Group 1) and 9% and 0% (Group 2). The respective median time to treatment failure and overall survival were 3 and 6.9 months (Group 1) and 1.5 and 5.9 months (Group 2). CONCLUSION: HAI oxaliplatin combined with capecitabine +/- bevacizumab was well-tolerated and was associated with favorable outcomes in selected patients.

Leukotriene B4-receptor-1 mediated host response shapes gut microbiota and controls colon tumor progression.

Inflammation and infection are key promoters of colon cancer but the molecular interplay between these events is largely unknown. Mice deficient in leukotriene B4 receptor1 (BLT1) are protected in inflammatory disease models of arthritis, asthma and atherosclerosis. In this study, we show that BLT1-/- mice when bred onto a spontaneous tumor (ApcMin/+) model displayed an increase in the rate of intestinal tumor development and mortality. A paradoxical increase in inflammation in the tumors from the BLT1-/-ApcMin/+ mice is coincidental with defective host response to infection. Germ-free BLT1-/-ApcMin/+ mice are free from colon tumors that reappeared upon fecal transplantation. Analysis of microbiota showed defective host response in BLT1-/- ApcMin/+ mice reshapes the gut microbiota to promote colon tumor development. The BLT1-/-MyD88-/- double deficient mice are susceptible to lethal neonatal infections. Broad-spectrum antibiotic treatment eliminated neonatal lethality in BLT1-/-MyD88-/- mice and the BLT1-/-MyD88-/-ApcMin+ mice are protected from colon tumor development. These results identify a novel interplay between the Toll-like receptor mediated microbial sensing mechanisms and BLT1-mediated host response in the control of colon tumor development.

Crystalline silica-induced leukotriene B4-dependent inflammation promotes lung tumour growth.

Chronic exposure to crystalline silica (CS) causes silicosis, an irreversible lung inflammatory disease that may eventually lead to lung cancer. In this study, we demonstrate that in K-ras(LA1) mice, CS exposure markedly enhances the lung tumour burden and genetic deletion of leukotriene B4 receptor-1 (BLT1(-/-)) attenuates this increase. Pulmonary neutrophilic inflammation induced by CS is significantly reduced in BLT1(-/-)K-ras(LA1) mice. CS exposure induces LTB4 production by mast cells and macrophages independent of inflammasome activation. In an air-pouch model, CS-induced neutrophil recruitment is dependent on LTB4 production by mast cells and BLT1 expression on neutrophils. In an implantable lung tumour model, CS exposure results in rapid tumour growth and decreased survival that is attenuated in the absence of BLT1. These results suggest that the LTB4/BLT1 axis sets the pace of CS-induced sterile inflammation that promotes lung cancer progression. This knowledge may facilitate development of immunotherapeutic strategies to fight silicosis and lung cancer.

Mediastinal paraganglioma between the great vessels in an 81-year-old woman.

Nonfunctional paragangliomas are slow-growing, typically benign tumors that arise from the extra-adrenal paraganglion of the autonomic nervous system. They are identified and characterized with the use of computed tomography and other imaging methods; for definitive diagnosis, histopathologic evaluation is crucial. Surgical resection is the treatment of choice, and results of postoperative biochemical testing can reveal recurrence. Because of this lesion's familial association, genetic testing is suggested. We report the case of an 81-year-old woman who presented with neck pain, intermittent palpitations, hypertension, and dyspnea. Contrast-enhanced computed tomography of the chest revealed a multilobular, high-density lesion between the aorta and the pulmonary artery in the superior mediastinum. The patient's 24-hour urinary vanillylmandelic acid levels were not elevated, which suggested a nonfunctional tumor. Mediastinal exploration revealed a large, vascular, irregular, consistently firm mass that adhered to the aortic arch. Upon histopathologic analysis after complete resection, the mass was determined to be a paraganglioma with a low index of mitosis. The patient had postoperative respiratory insufficiency that necessitated tracheostomy, but she recovered well after rehabilitation. In addition to reporting our patient's case, we discuss the nature, diagnosis, and treatment of paragangliomas.

Requirement for leukotriene B4 receptor 1 in allergen-induced airway hyperresponsiveness.

RATIONALE: Leukotriene B4 (LTB4) is a rapidly synthesized, early leukocyte chemoattractant that signals via its cell surface receptor, leukotriene B4 receptor 1 (BLT1), to attract and activate leukocytes during inflammation. A role for the LTB4-BLT1 pathway in allergen-induced airway hyperresponsiveness and inflammation is not well defined. OBJECTIVES: To define the role of the LTB4 receptor (BLT1) in the development of airway inflammation and altered airway function. METHODS: BLT1-deficient (BLT1 -/-) mice and wild-type mice were sensitized to ovalbumin by intraperitoneal injection and then challenged with ovalbumin via the airways. Airway responsiveness to inhaled methacholine, bronchoalveolar lavage fluid cell composition and cytokine levels, and lung inflammation and goblet cell hyperplasia were assessed. RESULTS: Compared with wild-type mice, BLT1 -/- mice developed significantly lower airway responsiveness to inhaled methacholine, lower goblet cell hyperplasia in the airways, and decreased interleukin (IL)-13 production both in vivo, in the bronchoalveolar lavage fluid, and in vitro, after antigen stimulation of lung cells in culture. Intracellular cytokine staining of lung cells revealed that bronchoalveolar lavage IL-13 levels and numbers of IL-13(+)/CD4+ and IL-13(+)/CD8+ T cells were also reduced in BLT1 -/- mice. Reconstitution of sensitized and challenged BLT1 -/- mice with allergen-sensitized BLT1 +/+ T cells fully restored the development of airway hyperresponsiveness. In contrast, transfer of naive T cells failed to do so. CONCLUSION: These data suggest that BLT1 expression on primed T cells is required for the full development of airway hyperresponsiveness, which appears to be associated with IL-13 production in these cells.