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Gastroenterology Feb 2021Immune checkpoint inhibitors have limited efficacy in many tumors. We investigated mechanisms of tumor resistance to inhibitors of programmed cell death-1 (PDCD1, also...
BACKGROUND & AIMS
Immune checkpoint inhibitors have limited efficacy in many tumors. We investigated mechanisms of tumor resistance to inhibitors of programmed cell death-1 (PDCD1, also called PD-1) in mice with gastric cancer, and the role of its ligand, PD-L1.
METHODS
Gastrin-deficient mice were given N-methyl-N-nitrosourea (MNU) in drinking water along with Helicobacter felis to induce gastric tumor formation; we also performed studies with H/K-ATPase-hIL1B mice, which develop spontaneous gastric tumors at the antral-corpus junction and have parietal cells that constitutively secrete interleukin 1B. Mice were given injections of an antibody against PD-1 or an isotype control before tumors developed, or anti-PD-1 and 5-fluorouracil and oxaliplatin, or an antibody against lymphocyte antigen 6 complex locus G (also called Gr-1), which depletes myeloid-derived suppressor cells [MDSCs]), after tumors developed. We generated knock-in mice that express PD-L1 specifically in the gastric epithelium or myeloid lineage.
RESULTS
When given to gastrin-deficient mice before tumors grew, anti-PD-1 significantly reduced tumor size and increased tumor infiltration by T cells. However, anti-PD-1 alone did not have significant effects on established tumors in these mice. Neither early nor late anti-PD-1 administration reduced tumor growth in the presence of MDSCs in H/K-ATPase-hIL-1β mice. The combination of 5-fluorouracil and oxaliplatin reduced MDSCs, increased numbers of intra-tumor CD8 T cells, and increased the response of tumors to anti-PD-1; however, this resulted in increased tumor expression of PD-L1. Expression of PD-L1 by tumor or immune cells increased gastric tumorigenesis in mice given MNU. Mice with gastric epithelial cells that expressed PD-L1 did not develop spontaneous tumors, but they developed more and larger tumors after administration of MNU and H felis, with accumulation of MDSCs.
CONCLUSIONS
In mouse models of gastric cancer, 5-fluorouracil and oxaliplatin reduce numbers of MDSCs to increase the effects of anti-PD-1, which promotes tumor infiltration by CD8 T cells. However, these chemotherapeutic agents also induce expression of PD-L1 by tumor cells. Expression of PD-L1 by gastric epithelial cells increases tumorigenesis in response to MNU and H felis, and accumulation of MDSCs, which promote tumor progression. The timing and site of PD-L1 expression is therefore important in gastric tumorigenesis and should be considered in design of therapeutic regimens.
Topics: Administration, Oral; Animals; Carcinogenesis; Gastric Mucosa; Gastrins; Helicobacter Infections; Helicobacter felis; Humans; Immune Checkpoint Inhibitors; Methylnitrosourea; Mice; Mice, Knockout; Myeloid-Derived Suppressor Cells; Neoplasms, Experimental; Programmed Cell Death 1 Receptor; Signal Transduction; Stomach Neoplasms; Tumor Microenvironment
PubMed: 33129844
DOI: 10.1053/j.gastro.2020.10.036 -
Molecular and Cellular Biology Jan 1987We developed highly sensitive shuttle vector systems for detection of mutations formed in human cells using autonomously replicating derivatives of Epstein-Barr virus...
We developed highly sensitive shuttle vector systems for detection of mutations formed in human cells using autonomously replicating derivatives of Epstein-Barr virus (EBV). EBV vectors carrying the bacterial lacI gene as the target for mutation were established in human cells and later returned to Escherichia coli for rapid detection and analysis of lacI mutations. The majority of the clonal cell lines created by establishment of the lacI-EBV vector show spontaneous LacI- frequencies of less than 10(-5) and are suitable for studies of induced mutation. The ability to isolate clonal lines represents a major advantage of the EBV vectors over transiently replicating shuttle vectors (such as those derived from simian virus 40) for the study of mutation. The DNA sequence changes were determined for 61 lacI mutations induced by exposure of one of the cell lines to N-nitroso-N-methylurea. A total of 33 of 34 lacI nonsense mutations and 26 of 27 missense mutations involve G X C to A X T transitions. These data provide support for the mutational theory of cancer.
Topics: Cell Line; Genetic Vectors; Herpesvirus 4, Human; Humans; Kidney; Methylnitrosourea; Mutation; Plasmids
PubMed: 3031469
DOI: 10.1128/mcb.7.1.379-387.1987 -
Environmental Health Perspectives Aug 1978Saccharin is carcinogenic for the urinary bladder in rats and mice, and most likely is carcinogenic in human beings. The neoplasms of the urinary bladder are malignant... (Review)
Review
Saccharin is carcinogenic for the urinary bladder in rats and mice, and most likely is carcinogenic in human beings. The neoplasms of the urinary bladder are malignant and invade and metastasize. Male rats are more susceptible to urinary bladder carcinogenesis than female rats. Rats exposed as fetuses develop neoplasms more readily than rats exposed as weanlings. The lesions in the urinary bladder go through the stages of hyperplasia, hyperplastic nodules, and later carcinomas. The male of the human species ingesting saccharin, as for rats, is more susceptible to carcinogenesis of the urinary bladder than the female. Neoplasms of the urinary bladder in rats were not caused by stones, parasites, sodium, or impurities. There is a cocarcinogenic effect between saccharin and methylnitrosurea for the urinary bladder. Even through carcinomas of the urinary bladder are present in rats given the higher doses of saccharin, one was observed in a female rat given 0.5%. Chronic renal disease develops in rats ingesting saccharin. The disease is more advanced at the lower doses than at the higher doses, suggesting that saccharin at the lower doses does not reach the urinary bladder. Early neoplasms are seen in the renal pelvis of rats given the higher doses of saccharin. The risk ratios for urinary bladder carcinomas in human beings increase with both frequency andduration of saccharin usage. Benign and malignant neoplasms at all sites are significantly increased in mice and rats ingesting the higher doses of saccharin. These neoplasms are present in the reproductive and hematopoietic systems, and to a lesser extent in the lungs, vascular system and squamous epithelium. Neoplasms in some organs develop with the lower doses of saccharin. Lymphosarcomas of the lung are significantly increased in rats given 0.01% saccharin. Chronic renal disease in rats given saccharin interferes with the health and life span and consequently with development of neoplasms. Saccharin initiates neoplasms of the skin when its application is followed by croton oil. Epidemiological studies have not been done for neoplasms other than the urinary bladder in human beings.
Topics: Animals; Carcinogens; Diet; Female; Lung Neoplasms; Male; Methylnitrosourea; Mice; Parasitic Diseases; Rats; Saccharin; Sex Factors; Species Specificity; Tosyl Compounds; United States; United States Food and Drug Administration; Urinary Bladder Calculi; Urinary Bladder Neoplasms; Urogenital Neoplasms
PubMed: 363408
DOI: 10.1289/ehp.7825173 -
Journal of Gastroenterology and... Jul 2016Gastric cancer is the third leading cause of cancer-related mortality worldwide. This is in part due to the asymptomatic nature of the disease, which often results in... (Review)
Review
Gastric cancer is the third leading cause of cancer-related mortality worldwide. This is in part due to the asymptomatic nature of the disease, which often results in late-stage diagnosis, at which point there are limited treatment options. Even when treated successfully, gastric cancer patients have a high risk of tumor recurrence and acquired drug resistance. It is vital to gain a better understanding of the molecular mechanisms underlying gastric cancer pathogenesis to facilitate the design of new-targeted therapies that may improve patient survival. A number of chemically and genetically engineered mouse models of gastric cancer have provided significant insight into the contribution of genetic and environmental factors to disease onset and progression. This review outlines the strengths and limitations of current mouse models of gastric cancer and their relevance to the pre-clinical development of new therapeutics.
Topics: Animals; Disease Models, Animal; Gastrins; Helicobacter Infections; Helicobacter felis; Helicobacter pylori; Methylnitrosourea; Mice, Inbred Strains; Mice, Transgenic; Molecular Targeted Therapy; Stomach Neoplasms
PubMed: 26809278
DOI: 10.1111/jgh.13297 -
Asian Pacific Journal of Cancer... Jan 2021Testicular cancer is a public health problem. The goal of this study was to demonstrate the efficacy of quercetin treatment on N-nitroso-N-methyl-urea (MNU)-induced...
BACKGROUND
Testicular cancer is a public health problem. The goal of this study was to demonstrate the efficacy of quercetin treatment on N-nitroso-N-methyl-urea (MNU)-induced testicular carcinogenesis alone or in combination with cisplatin-treatment.
METHODS
In total 70 adult male albino rats were categorized into six groups, control, quercetin-treatment (10 mg/kg body weight), cisplatin-treatment (2 mg/kg. body weight), cisplatin and quercetin-treatment, MNU-treatment, MNU plus quercetin-treatment and MNU plus quercetin and cisplatin-treatment. Treatment with quercetin and/or cisplatin was performed after 2 months of MNU induced testicular carcinogenesis. The studied groups were euthanized and sacrificed and their testes were examined for gene expression, biochemical, histological and immunohistochemically analysis, inflammation and apoptosis of germ cells.
RESULTS
The fertility of the rats subjected to MNU carcinogenesis was impaired following cisplatin and/or quercetin-treatment. Cisplatin-treatment reduced the fertility rate and improved after quercetin-treatment. Quercetin-treatment decreased the sharp increase in RNA expression of BAX and MPO in both cisplatin-toxicated testes and after MNU carcinogenesis induction. In addition, the testicular levels of testosterone and SOD increased in parallel with depletion of MDA, IL-6, AFP and caspase-3 levels in MNU and/or cisplatin-treatment after -quercetin-treatment. The testicular structure of the cisplatin-treated group recovered their dividing germ and sperm differentiation after-quercetin-treatment. While, there was a great appearance of flourishing germ cell of MNU carcinogenesis post quercetin therapy, there was still a lack of sperm differentiation. Conclusion: Quercetin-treatment showed increased cisplatin activity and decreased testicular carcinogenesis due to anti-neoplastic and antioxidant activities.
Topics: Alkylating Agents; Animals; Antineoplastic Agents; Antioxidants; Apoptosis; Biomarkers, Tumor; Carcinogenesis; Cell Proliferation; Cisplatin; Drug Synergism; Drug Therapy, Combination; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Male; Methylnitrosourea; Quercetin; Rats; Rats, Wistar; Testicular Neoplasms
PubMed: 33507682
DOI: 10.31557/APJCP.2021.22.1.75 -
PloS One 2023Carcinogenicity tests predict the tumorigenic potential of various substances in the human body by studying tumor induction in experimental animals. There is a need for...
Carcinogenicity tests predict the tumorigenic potential of various substances in the human body by studying tumor induction in experimental animals. There is a need for studies that explore the use of FVB/N-Trp53em2Hwl/Korl (FVB-Trp53+/-) mice, created by TALEN-mediated gene targeting in Korea, in carcinogenicity tests. This study was performed to determine whether FVB-Trp53+/- mice are a suitable model for short-term carcinogenicity studies. To compare the carcinogenicity at different concentrations, 25, 50, and 75 mg/kg of N-methyl-N-nitrosourea (MNU), a known carcinogen, were administered intraperitoneally to FVB-Trp53+/- and wild-type male mice. After 26 weeks, the survival rate was significantly reduced in FVB-Trp53+/- mice compared to the wild-type mice in the 50 and 75 mg/kg groups. The incidence of thymic malignant lymphoma (TML) in the 50 and 75 mg/kg groups was 54.2 and 59.1% in FVB-Trp53+/- male mice, respectively. TML metastasized to the lungs, spleen, lymph nodes, liver, kidney, and heart in FVB-Trp53+/- male mice. Furthermore, the incidence of primary lung tumors, such as adenomas and adenocarcinomas, was 65.4, 62.5, and 45.4% in the FVB-Trp53+/- mice of the 25, 50, and 75 mg/kg groups, respectively. The main tumor types in FVB-Trp53+/- mice were TML and primary lung tumors, regardless of the dose of MNU administered. These results suggest that systemic tumors may result from malfunctions in the p53 gene and pathway, which is an important factor in the pathogenesis of human cancers. Therefore, FVB-Trp53 heterozygous mice are suitable for short-term carcinogenicity tests using positive carcinogens, and that the best result using MNU, a positive carcinogen, might have a single dose of 50 mg/kg.
Topics: Humans; Mice; Male; Animals; Methylnitrosourea; Carcinogens; Mice, Inbred Strains; Thymus Neoplasms; Lung Neoplasms; Carcinogenicity Tests
PubMed: 36608059
DOI: 10.1371/journal.pone.0280214 -
STAR Protocols Dec 2021N-Methyl-N-nitrosourea, an N-nitroso compound converted from dietary nitrite by , causes somatic mutations in epithelial cells and induces gastric premalignancy. Here,...
N-Methyl-N-nitrosourea, an N-nitroso compound converted from dietary nitrite by , causes somatic mutations in epithelial cells and induces gastric premalignancy. Here, we describe a detailed protocol for induction of gastric tumor and analysis of tumor phenotypes in mice. This model can be widely used for studying the initiation and growth of gastric cancer. For complete details on the use and execution of this protocol, please refer to Li et al. (2021).
Topics: Animals; Male; Methylnitrosourea; Mice; Mice, Inbred C57BL; Neoplasms, Experimental; Stomach; Stomach Neoplasms
PubMed: 34585155
DOI: 10.1016/j.xpro.2021.100814 -
PloS One 2016Ofd1 is a newly identified causative gene for Retinitis pigmentosa (RP), a photoreceptor degenerative disease. This study aimed to examine Ofd1 localization in retina...
Ofd1 is a newly identified causative gene for Retinitis pigmentosa (RP), a photoreceptor degenerative disease. This study aimed to examine Ofd1 localization in retina and further to investigate its function in photoreceptor degeneration models. Ofd1 localization in rat retina was examined using immunofluorescence. N-methyl-N-nitrosourea (MNU)-induced rats and Royal College of Surgeons (RCS) rats were used as photoreceptor degeneration models. The expression pattern of Ofd1, other ciliary associated genes and Wnt signaling pathway genes were examined in rat models. Furthermore, pEGFP-Ofd1-CDS and pSUPER-Ofd1-shRNA were constructed to overexpress and knockdown the expression level in 661W and R28 cells. MNU was also used to induce cell death. Cilia formation was observed using immunocytochemistry (ICC). Reactive oxygen species (ROS) were detected using the 2', 7'-Dichlorofluorescin diacetate (DCFH-DA) assay. Apoptosis genes expression was examined using qRT-PCR, Western blotting and fluorescence-activated cell sorting (FACS). Ofd1 localized to outer segments of rat retina photoreceptors. Ofd1 and other ciliary proteins expression levels increased from the 1st and 4th postnatal weeks and decreased until the 6th week in the RCS rats, while their expression consistently decreased from the 1st and 7th day in the MNU rats. Moreover, Wnt signaling pathway proteins expression was significantly up-regulated in both rat models. Knockdown of Ofd1 expression resulted in a smaller population, shorter length of cell cilia, and lower cell viability. Ofd1 overexpression partially attenuated MNU toxic effects by reducing ROS levels and mitigating apoptosis. To the best of our knowledge, this is the first study demonstrating Ofd1 localization and its function in rat retina and in retinal degeneration rat models. Ofd1 plays a role in controlling photoreceptor cilium length and number. Importantly, it demonstrates a neuroprotective function by protecting the photoreceptor from oxidative stress and apoptosis. These data have expanded our understanding of Ofd1 function beyond cilia, and we concluded that ofd1 neuroprotection could be a potential treatment strategy in retina degeneration models.
Topics: Animals; Antioxidants; Apoptosis; Cell Death; Cell Line; Cell Separation; Cilia; Ciliopathies; Electroretinography; Flow Cytometry; Immunohistochemistry; Methylnitrosourea; Mice; Oxidative Stress; Photoreceptor Cells; Photoreceptor Cells, Vertebrate; Plasmids; Proteins; RNA, Small Interfering; Rats; Reactive Oxygen Species; Retina; Retinal Degeneration; Retinitis Pigmentosa; Signal Transduction; Stem Cells
PubMed: 27196396
DOI: 10.1371/journal.pone.0155860 -
Carcinogenesis Jul 2010Emerging evidence indicates that intrinsic differences and induced changes in aerobic capacity are probably to play a critical role in the development of chronic...
Emerging evidence indicates that intrinsic differences and induced changes in aerobic capacity are probably to play a critical role in the development of chronic diseases like cancer. This study was initiated: (i) to determine how citrate synthase activity, which is routinely used as a marker of aerobic capacity and mitochondrial density in skeletal muscle, was affected by voluntary running on either a motorized activity wheel or a non-motorized free wheel and (ii) to investigate the association between aerobic capacity and the carcinogenic response induced in the mammary gland by intraperitoneal injection of 1-methyl-1-nitrosurea. Overall, wheel running reduced cancer incidence (96 versus 72%, P = 0.0006) and the number of cancers per animal (2.84 versus 1.78, P < 0.0001) and induced citrate synthase activity (276 versus 353 U/mg, P < 0.0001, sedentary control versus wheel running,respectively). Both motorized and free wheel running increased citrate synthase activity (373 +/- 24, 329 +/- 11 and 276 +/- 9 U/mg protein, P < 0.0001) and reduced the average number of cancers per rat (2.84, 1.96 and 1.63, P < 0.01), sedentary control, free wheel and motorized wheel, respectively. However, regression analyses failed to provide evidence of a significant association between citrate synthase activity and either cancer incidence or cancer multiplicity. Citrate synthase activity is a single measure in a complex pathway that determines aerobic capacity. The multifaceted nature of intrinsic and inducible aerobic capacity limits the usefulness of citrate synthase activity alone in elucidating the relationship between aerobic capacity and the carcinogenic response.
Topics: Aerobiosis; Animals; Citrate (si)-Synthase; Female; Logistic Models; Mammary Neoplasms, Experimental; Methylnitrosourea; Muscle, Skeletal; Oxygen Consumption; Physical Conditioning, Animal; Rats; Rats, Sprague-Dawley; Running; Tumor Suppressor Protein p53
PubMed: 20299525
DOI: 10.1093/carcin/bgq063