Web-based access to mouse models of human cancers: the Mouse Tumor Biology (MTB) Database

The Mouse Tumor Biology (MTB) Database serves as a curated, integrated resource for information about tumor genetics and pathology in genetically defined strains of mice (i.e., inbred, transgenic and targeted mutation strains). Sources of information for the database include the published scientific literature and direct data submissions by the scientific community. Researchers access MTB using Web-based query forms and can use the database to answer such questions as 'What tumors have been reported in transgenic mice created on a C57BL/6J background?', 'What tumors in mice are associated with mutations in the Trp53 gene?' and 'What pathology images are available for tumors of the mammary gland regardless of genetic background?'. MTB has been available on the Web since 1998 from the Mouse Genome Informatics web site (http://www.informatics.jax.org). We have recently implemented a number of enhancements to MTB including new query options, redesigned query forms and results pages for pathology and genetic data, and the addition of an electronic data submission and annotation tool for pathology data.     

Mouse models of human diseases.

Cancer, poliomyelitis, Alzheimer's and Gaucher disease, a seemingly disparate array of disorders, have become the target of powerful genetic analysis and drug screening protocols, using mouse strains that have been genetically altered to serve as models for understanding the disease and for helping the patient.     

Preclinical models for interrogating drug action in human cancers using Stable Isotope Resolved Metabolomics (SIRM)

Objectives

In this review we compare the advantages and disadvantages of different model biological systems for determining the metabolic functions of cells in complex environments, how they may change in different disease states, and respond to therapeutic interventions.

Introduction

All preclinical drug-testing models have advantages and drawbacks. We compare and contrast established cell, organoid and animal models with ex vivo organ or tissue culture and in vivo human experiments in the context of metabolic readout of drug efficacy. As metabolism reports directly on the biochemical state of cells and tissues, it can be very sensitive to drugs and/or other environmental changes. This is especially so when metabolic activities are probed by stable isotope tracing methods, which can also provide detailed mechanistic information on drug action. We have developed and been applying Stable Isotope-Resolved Metabolomics to examine metabolic reprogramming of human lung cancer cells in monoculture, in mouse xenograft/explant models, and in lung cancer patients in situ (Lane et al. in Omics 15:173–182, 2011; Fan et al. in Metabolomics 7(2):257–269, 2011a, in Pharmacol Ther 133:366–391, 2012a, in Metabolomics 8(3):517–527, b; Xie et al. in Cell Metab 19:795–809, 2014; Ren et al. in Sci Rep 4:5414, 2014; Sellers et al. in J Clin Investig 125(2):687–698, 2015). We are able to determine the influence of the tumor microenvironment using these models. We have now extended the range of models to fresh human tissue slices, similar to those originally described by Warburg (Biochem Z 142:317–333, 1923), which retain the native tissue architecture and heterogeneity with a paired benign versus cancer design under defined cell culture conditions. This platform offers an unprecedented human tissue model for preclinical studies on metabolic reprogramming of human cancer cells in their tissue context, and response to drug treatment (Xie et al. 2014). As the microenvironment of the target human tissue is retained and individual patient’s response to drugs is obtained, this platform promises to transcend current limitations of drug selection for clinical trials or treatments

Conclusions

Development of ex vivo human tissue and animal models with humanized organs including bone marrow and liver show considerable promise for analyzing drug responses that are more relevant to humans. Similarly using stable isotope tracer methods with these improved models in advanced stages of the drug development pipeline, in conjunction with tissue biopsy is expected significantly to reduce the high failure rate of experimental drugs in Phase II and III clinical trials.

     

Mouse models expressing human carcinoembryonic antigen (CEA) as a transgene: evaluation of CEA-based cancer vaccines

In recent years, investigators have carried out several studies designed to evaluate whether human tumor-associated antigens might be exploited as targets for active specific immunotherapy, specifically human cancer vaccines. Not too long ago such an approach would have been met with considerable skepticism because the immune system was believed to be a rigid discriminator between self and non-self which, in turn, protected the host from a variety of pathogens. That viewpoint has been challenged in recent years by a series of studies indicating that antigenic determinants of self have not induced absolute host immune tolerance. Moreover, under specific conditions that evoke danger signals, peptides from self-antigen can be processed by the antigen-presenting cellular machinery, loaded onto the major histocompatibility antigen groove to serve as targets for immune intervention. Those findings provide the rationale to investigate a wide range of tumor-associated antigens, including differentiation antigens, oncogenes, and tumor suppressor genes as possible immune-based targets. One of those tumor-associated antigens is the carcinoembryonic antigen (CEA). Described almost 40 years ago, CEA is a M(r) 180-200,000 oncofetal antigen that is one of the more widely studied human tumor-associated antigens. This review will provide: (i) a brief overview of the CEA gene family, (ii) a summary of early preclinical findings on overcoming immune tolerance to CEA, and (iii) the rationale to develop mouse models which spontaneously develop gastrointestinal tumors and express the CEA transgene. Those models have been used extensively in the study of overcoming host immune tolerance to CEA, a self, tumor-associated antigen, and the experimental findings have served as the rationale for the design of early clinical trials to evaluate CEA-based cancer vaccines.     

Specific cytosol binding proteins for 25(OH)D3 and 1.25(OH)2D3 in human breast cancers

Binding proteins for 1.25 (OH) 2D3 were investigated in thirty breast cancers. Human breast cancer was shown to contain specific, high affinity cytosol binding proteins for 1.25 (OH) 2D3 and 25 (OH) D3. The binding protein for 1.25 (OH) 2D3 sedimented at 3.7 S and the binding protein for 25 (OH) D3 at about 6.0 S on sucrose density gradient analysis containing 0.3 M KCl and 1 mM dithiothreitol in buffer. Kd for 1.25 (OH) 2D3 were from 0.1 x 10(-11) M to 7.1 x 10(-11) M measured by Scatchard plots. Competition binding studies indicated that the relative specificity of the binding protein for 1.25 (OH) 2D3 much greater than 25 (OH) D3 greater than 1 alpha (OH) D3, 24,25 (OH)2D3 greater than D3 much greater than Estradiol-17 beta. 1.25 (OH) 2D3 receptor-positive was detected in twenty-eight out of thirty breast cancers.     

Mouse models of atherosclerosis

Atherosclerosis bears many features of a chronic inflammation that affects the intima of large and medium-sized arteries. In recent years apolipoprotein E-deficient and LDL receptor-deficient mice have been used to examine the effects of various gene products on the development of atherosclerosis. In the present review the effects of genetics, apolipoprotein E, inflammatory gene modifiers, lipoprotein modifications, lipoprotein receptors, vessel wall expression of lipoprotein-metabolizing enzymes, and the atheroprotective role of HDL on atherosclerosis in these mice are discussed. The importance of examining lesions that are more advanced than fatty streaks and careful histologic and immunologic examination of lesion composition is emphasized.     

Mouse models of the laminopathies

The A and B type lamins are nuclear intermediate filament proteins that comprise the bulk of the nuclear lamina, a thin proteinaceous structure underlying the inner nuclear membrane. The A type lamins are encoded by the lamin A gene (LMNA). Mutations in this gene have been linked to at least nine diseases, including the progeroid diseases Hutchinson-Gilford progeria and atypical Werner's syndromes, striated muscle diseases including muscular dystrophies and dilated cardiomyopathies, lipodystrophies affecting adipose tissue deposition, diseases affecting skeletal development, and a peripheral neuropathy. To understand how different diseases arise from different mutations in the same gene, mouse lines carrying some of the same mutations found in the human diseases have been established. We, and others have generated mice with different mutations that result in progeria, muscular dystrophy, and dilated cardiomyopathy. To further our understanding of the functions of the lamins, we also created mice lacking lamin B1, as well as mice expressing only one of the A type lamins. These mouse lines are providing insights into the functions of the lamina and how changes to the lamina affect the mechanical integrity of the nucleus as well as signaling pathways that, when disrupted, may contribute to the disease.     

Mouse models of insulin resistance

The hallmarks of type 2 diabetes are impaired insulin action in peripheral tissues and decreased pancreatic beta-cell function. Classically, the two defects have been viewed as separate entities, with insulin resistance arising primarily from impaired insulin-dependent glucose uptake in skeletal muscle, and beta-cell dysfunction arising from impaired coupling of glucose sensing to insulin secretion. Targeted mutagenesis and transgenesis involving components of the insulin action pathway have changed our understanding of these phenomena. It appears that the role of insulin signaling in the pathogenesis of type 2 diabetes has been overestimated in classic insulin target tissues, such as skeletal muscle, whereas it has been overlooked in liver, pancreatic beta-cells, and brain, which had been thought not to be primary insulin targets. We review recent progress and try to reconcile areas of apparent controversy surrounding insulin signaling in skeletal muscle and pancreatic beta-cells.     

Somatic mutations of CASP3 gene in human cancers

Failure of apoptosis is one of the hallmarks of cancer. As an execution-phase caspase, caspase-3 plays a crucial role during apoptosis. To explore the possibility that the genetic alterations of CASP3, which encodes caspase-3, might be involved in the development of human tumors, we analyzed the entire coding region and all splice sites of human CASP3 gene for the detection of somatic mutations in a series of 944 human tumors, including 165 stomach carcinomas, 95 colon carcinomas, 76 breast carcinomas, 80 hepatocellular carcinomas, 181 non-small cell lung cancers, 45 acute leukemias, 28 multiple myelomas, 12 medulloblastomas, 15 Wilms tumors, 12 renal cell carcinomas, 40 esophagus carcinomas, 33 urinary bladder carcinomas, 33 laryngeal carcinomas, and 129 non-Hodgkin lymphomas. Overall, we detected 14 somatic mutations of the CASP3 gene, including six missense and four silent mutations, two mutations in the introns, one mutation in the 5-untranslated region, and one mutation in the 3-untranslated region. The mutations were observed in four of 98 colon carcinomas (4.1%), four of 181 non-small cell lung cancers (2.2%), two of 129 non-Hodgkin lymphomas (1.6%), two of 165 stomach carcinomas (1.2%), one of 80 hepatocellular carcinomas (1.3%), and one of 28 multiple myelomas (3.6%). This is the first report on CASP3 gene mutations in human tumors; these data indicate that the CASP3 gene is occasionally mutated in human tumors.