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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 -
Ecotoxicology and Environmental Safety Jul 2022N-methyl-N-nitrosourea (MNU) is a prevalent environmental carcinogen, which leads to tumors in various organs in animal models, while the mechanisms involved were still...
N-methyl-N-nitrosourea (MNU) is a prevalent environmental carcinogen, which leads to tumors in various organs in animal models, while the mechanisms involved were still not fully understood. It is well known that anomalous angiogenesis is a key step in tumorigenesis and progression. In this study, we found that MNU induced abnormal angiogenesis which was accompanied by upregulation of rspo1, p53 and vegfaa in zebrafish embryos. Moreover, it revealed that MNU-induced ectopic sprouting of blood vessels was significantly reduced in rspo1-knockdown but not p53-knockdown embryos, indicating that rspo1 was necessary for MNU-induced abnormal angiogenesis. Additionally, pharmaceutical activation or inhibition of Wnt/β-catenin signaling pathway using (2'Z,3'E)- 6-bromoindirubin-3'-oxime or CCT036477 significantly increased or inhibited the pro-angiogenic effect of MNU on developing zebrafish embryos, which was confirmed by the effect of proliferation and migration in MNU-treated bEnd.3 cells. These data together indicated that rspo1/Wnt/β-catenin/vegfaa axis is involved in the modulation of MNU-induced anomalous angiogenesis.
Topics: Animals; Endothelial Cells; Methylnitrosourea; Mice; Neovascularization, Pathologic; Wnt Signaling Pathway; Zebrafish; beta Catenin
PubMed: 35623148
DOI: 10.1016/j.ecoenv.2022.113674 -
The Prostate Aug 2022There is evidence to suggest that green tea soy may have protective effects against prostate cancer, but there are several epidemiologic and clinical studies that did...
BACKGROUND
There is evidence to suggest that green tea soy may have protective effects against prostate cancer, but there are several epidemiologic and clinical studies that did not identify such an effect. We tested the notion of protective effects in a rat model of prostate carcinogenesis that has been predictive of the effects of selenium and vitamin E in randomized clinical trials and a human prostate cancer xenograft model in nude mice and rat prostate tumor cells transplanted in immune-competent syngeneic animals.
METHODS
Prostate cancer was induced in rats with methylnitrosourea and testosterone and tumor incidence was determined. Subcutaneous tumor growth was measured resulting from injected cells isolated from rat prostate cancers grafted in syngeneic animals and from the prostate-specific antigen (PSA)-producing human prostate cancer PC346 xenografted in nude mice. Brewed decaffeinated green tea infusion or caffeinated green tea extract and the same 300 mg/ml concentration of caffeine were provided in drinking water of the rats and nude mice.
RESULTS
Caffeinated green tea extract and caffeine provided in drinking water did not modify the induction of prostate cancer in the rat model compared with control rats. The same drinking water treatments also did not affect the growth and PSA production of PC346 human prostate cancer xenografts in nude mice and the growth of two transplantable rat prostate cancer tumor lines in Wistar Firth rats. Brewed green tea infusion as drinking water did also not affect tumor growth in these xeno- and allograft models.
CONCLUSION
These animal studies with drinking water exposure to green tea and caffeine do not support the idea that green tea is protective against prostate cancer.
Topics: Animals; Caffeine; Carcinogenesis; Disease Models, Animal; Drinking Water; Heterografts; Humans; Male; Mice; Mice, Nude; Plant Extracts; Prostate; Prostate-Specific Antigen; Prostatic Neoplasms; Rats; Rats, Wistar; Tea
PubMed: 35485427
DOI: 10.1002/pros.24364