Chemopreventative effect of an inducible nitric oxide synthase inhibitor, ONO-1714, on inflammation-associated biliary carcinogenesis in hamsters

Unveiling the significance of inducible nitric oxide synthase: Its impact on cancer progression and clinical implications

The intricate role of inducible nitric oxide synthase (iNOS) in cancer pathophysiology has garnered significant attention, highlighting the complex interplay between tumorigenesis, immune response, and cellular metabolism. As an enzyme responsible for producing nitric oxide (NO) in response to inflammatory stimuli. iNOS is implicated in various aspects of cancer development, including DNA damage, angiogenesis, and evasion of apoptosis. This review synthesizes the current findings from both preclinical and clinical studies on iNOS across different cancer types, reflecting the variability depending on cellular context and tumor microenvironment. We explore the molecular mechanisms by which iNOS modulates cancer cell growth, survival, and metastasis, emphasizing its impact on immune surveillance and response to treatment. Additionally, the potential of targeting iNOS as a therapeutic strategy in cancer treatment is examined. By integrating insights from recent advances, this review aims to elucidate the significant role of iNOS in cancer and pave the way for novel diagnostic and therapeutic approaches.

Genetically Engineered Hamster Models of Dyslipidemia and Atherosclerosis

Animal models of human diseases play an extremely important role in biomedical research. Among them, mice are widely used animal models for translational research, especially because of ease of generation of genetically engineered mice. However, because of the great differences in biology between mice and humans, translation of findings to humans remains a major issue. Therefore, the exploration of models with biological and metabolic characteristics closer to those of humans has never stopped.Although pig and nonhuman primates are biologically similar to humans, their genetic engineering is technically difficult, the cost of breeding is high, and the experimental time is long. As a result, the application of these species as model animals, especially genetically engineered model animals, in biomedical research is greatly limited.In terms of lipid metabolism and cardiovascular diseases, hamsters have several characteristics different from rats and mice, but similar to those in humans. The hamster is therefore an ideal animal model for studying lipid metabolism and cardiovascular disease because of its small size and short reproduction period. However, the phenomenon of zygote division, which was unexpectedly blocked during the manipulation of hamster embryos for some unknown reasons, had plagued researchers for decades and no genetically engineered hamsters have therefore been generated as animal models of human diseases for a long time. After solving the problem of in vitro development of hamster zygotes, we successfully prepared enhanced green fluorescent protein (eGFP) transgenic hamsters by microinjection of lentiviral vectors into the zona pellucida space of zygotes. On this basis, we started the development of cardiovascular disease models using the hamster embryo culture system combined with the novel genome editing technique of clustered regularly interspaced short palindromic repeats (CRISPR )/CRISPR associated protein 9 (Cas9). In this chapter, we will introduce some of the genetically engineered hamster models with dyslipidemia and the corresponding characteristics of these models. We hope that the genetically engineered hamster models can be further recognized and complement other genetically engineered animal models such as mice, rats, and rabbits. This will lead to new avenues and pathways for the study of lipid metabolism and its related diseases.

Chemopreventive Strategies for Inflammation-Related Carcinogenesis: Current Status and Future Direction

A sustained and chronically-inflamed environment is characterized by the presence of heterogeneous inflammatory cellular components, including neutrophils, macrophages, lymphocytes and fibroblasts. These infiltrated cells produce growth stimulating mediators (inflammatory cytokines and growth factors), chemotactic factors (chemokines) and genotoxic substances (reactive oxygen species and nitrogen oxide) and induce DNA damage and methylation. Therefore, chronic inflammation serves as an intrinsic niche for carcinogenesis and tumor progression. In this article, we summarize the up-to-date findings regarding definitive/possible causes and mechanisms of inflammation-related carcinogenesis derived from experimental and clinical studies. We also propose 10 strategies, as well as candidate agents for the prevention of inflammation-related carcinogenesis.

Genomic organization and expression of immunoglobulin genes in the Chinese hamster (Cricetulus griseus)

In science, the hamsters are widely used as a model for studying the human diseases because they display many features like humans. The utility of the Chinese hamster as a biology model can be further enhanced by further characterization of the genes encoding components of the immune system. Here, we report the genomic organization and expression of the Chinese hamster immunoglobulin heavy and light chain genes. The Chinese hamster IgH locus contains 268 VH segments (132 potentially functional genes, 12 ORFs and 124 pseudogenes), 4 DH segments, 6 JH segments, four constant region genes (μ, γ, ε and α) and one reverse δ remnant fragment. The Igκ locus contains only a single Cκ gene, 4 Jκ segments and 48 Vκ segments (15 potentially functional genes and 33 pseudogenes), whereas the Igλ locus contains 4 Cλ genes, but only Cλ 3 and Cλ 4 each preceded by a Jλ gene segment. A total of 49 Vλ segments (39 potentially functional genes, 3 ORFs and 7 pseudogenes) were identified. Analysis of junctions of the recombined V(D)J transcripts reveals complex diversity in both expressed H and κ sequences, but the microhomology-directed VJ recombination obviously results in very limited diversity in the Chinese hamster λ gene despite more potential germline-encoded combinatorial diversity. This is the first study to make a comprehensive analysis of the Ig genes in the Chinese hamster, which provides insights into the Ig genes in placental mammals.

Involvement of MMP-9 in peribiliary fibrosis and cholangiocarcinogenesis via Rac1-dependent DNA damage in a hamster model

Peribiliary fibrosis caused by chronic infection with Opisthorchis viverrini (OV) is a risk factor of cholangiocarcinoma (CCA) in northeastern Thailand. Matrix metalloproteinases (MMPs) are enzymes capable of degrading and remodeling the extracellular matrix in the process of fibrosis and carcinogenesis. We examined MMPs expression and their role in fibrogenesis and cholangiocarcinogenesis in hamsters treated with OV and N-nitrosodimethylamine (NDMA). We assessed the time profiles of MMPs, inducible nitric oxide synthase (iNOS), Rac1, α-smooth muscle actin (α-SMA) and DNA lesions (8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine, 8-oxodG) in relation to fibrosis and CCA development. Histopathology revealed OV and NDMA synergistically induced peribiliary fibrosis time-dependently, and CCA occurred at 3 months, whereas OV or NDMA alone induced less fibrosis. Hydroxyproline levels in the liver and plasma were positively associated with the expression of collagen I and α-SMA. MMP-9 expression was significantly increased and correlated with the accumulation of myofibroblast, fibrosis levels and cholangiocarcinogenesis. MMP-9 activity was correlated with iNOS, and immunocolocalization was observed in inflammed tissues, early and invasive CCA. OV and NDMA synergistically induced MMP-9 expression in association to Rac1. In addition, Rac1 was colocalized with iNOS, and 8-nitroguanine, in inflammed tissues and CCA. Formation of 8-nitroguanine and 8-oxodG increased with tumor progression. The results suggest that MMP-9 expression is associated with the accumulation of peribiliary fibrosis in conjunction to the induction of iNOS and Rac1 that may potentiate DNA damage and cholangiocarcinogenesis.

Reduction of periductal fibrosis in liver fluke-infected hamsters after long-term curcumin treatment

Chronic infection with the liver fluke, Opisthorchis viverrini, induces advanced periductal fibrosis and is a relative risk factor for cholangiocarcinoma in Southeastern Asia. We examined the reducing effect of curcumin on hepatobiliary fibrosis using O. viverrini-infected hamsters supplemented with dietary 1% curcumin (w/w) as an animal model. The expression profile of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs), cytokines, and collagens was assessed in relation to liver fibrosis. Histopathological studies revealed that curcumin had no effect on fibrosis at the short-term infection (21 days and 1 month); however, peribiliary fibrosis was significantly reduced after the long-term curcumin treatment for 3 months, compared to the untreated group. Expression of alpha-smooth muscle actin was associated with the reduction of liver fibrosis. A decrease in hepatic hydroxyproline level and mRNA expression of collagen I and III supported the reduction of fibrosis. The expression of TIMP-1, TIMP-2, and tumor necrosis factor-alpha genes was also decreased after curcumin treatment. In contrast, curcumin increased mRNA expression of MMP-13, MMP-7 (at 6 months), interleukin-1 beta, and transforming growth factor beta, implying that increased MMPs activity contributes to extracellular matrix degradation. These results suggest that curcumin reduces periductal fibrosis after long-term treatment by tissue resorption via inhibition of TIMPs expression and enhancement of MMPs expression mediated by cytokines. In conclusion, curcumin may serve as a promising nutraceutical agent exerting antifibrotic effect in O. viverrini-infected patients and contribute to cholangiocarcinoma prevention.