8-nitroguanine and Cell-Transformation--Neoplastic

Chronic inflammation contributes to a substantial part of environmental carcinogenesis. Various infectious diseases and physical, chemical, and immunological factors participate in inflammation-related carcinogenesis. Under inflammatory conditions, reactive oxygen and nitrogen species are generated from inflammatory and epithelial cells, and resulting DNA damage may participate in carcinogenesis. 8-Nitroguanine is a mutagenic DNA lesion formed during chronic inflammation. We performed immunohistochemical analysis, and demonstrated that 8-nitroguanine was formed at the sites of carcinogenesis in animal models and patients with various cancer-prone infectious and inflammatory diseases, caused by parasites, viruses, and asbestos exposure. In asbestos-exposed mice, 8-nitroguanine was formed in bronchial epithelial cells, and it is noteworthy that crocidolite induced significantly more intense 8-nitroguanine formation than chrysotile, inconsistent with their carcinogenic potentials. On the basis of these findings, we have proposed that 8-nitroguanine could be a potential biomarker to evaluate the risk of inflammation-related carcinogenesis.

Topics: Animals; Asbestos; Bacterial Infections; Biomarkers, Tumor; Cell Transformation, Neoplastic; DNA Damage; Guanine; Humans; Inflammation Mediators; Nitric Oxide Synthase Type II; Parasitic Diseases; Virus Diseases

Nitric oxide (NO) and superoxide rapidly react to yield peroxynitrite. Peroxynitrite is a potent oxidant which reacts with proteins, lipids, and DNA. The present paper overviews the various DNA modifications induced by exposure to peroxynitrite or NO and superoxide concurrently, with special reference to the formation of 8-nitroguanine and 8-oxoguanine as well as the induction of DNA single strand breakage. In addition, we review the secondary processes that may follow the process of DNA damage, such as activation of the nuclear enzyme, poly(ADP-ribose) synthetase, apoptosis, and carcinogenesis.

Topics: Animals; Apoptosis; Cell Transformation, Neoplastic; DNA; DNA Damage; Guanine; Humans; Inflammation; Nitrates; Nitric Oxide; Oxidants; Poly(ADP-ribose) Polymerases; Superoxides

Nitrative and oxidative DNA damage plays an important role in inflammation-related carcinogenesis. Chronic inflammation such as parasite infection and primary sclerosing cholangitis can be an etiological factor of cholangiocarcinoma. Using a proteomic approach and double-fluorescent staining, we identified high expression and colocalization of albumin and cytokeratin-19 in liver fluke-associated cholangiocarcinoma tissues, compared with normal livers from cholangiocarcinoma patients and cadaveric donors, respectively. Albumin was detected not only in cells of hyperplastic bile ducts and cholangiocarcinoma, but also in liver stem/progenitor cell origin, such as canal of Hering, ductules, and ductular reactions, suggesting the involvement of stem/progenitor cells in cholangiocarcinoma development. To clarify the involvement of liver stem/progenitor cells in cholangiocarcinoma, we examined several stem/progenitor cell markers (CD133, CD44, OV6, and Oct3/4) in cholangiocarcinoma tissues analyzed by immunohistochemical staining, and measured 8-oxodG levels by using HPLC-ECD as an inflammation-related DNA lesion. In addition, a stem/progenitor cell factor Bmi1, 8-nitroguanine (formed during nitrative DNA damage), DNA damage response (DDR) proteins (phosphorylated ATM and γ-H2AX), and manganese-SOD (Mn-SOD) were analyzed by immunohistochemistry. Stem/progenitor cell markers (CD133, OV6, CD44, and Oct3/4) were positively stained in 56, 38, 47, and 56% of 34 cholangiocarcinoma cases, respectively. Quantitative analysis of 8-oxodG revealed significantly increased levels in CD133- and/or Oct3/4-positive tumor tissues compared to negative tumor tissues, as well as 8-nitroguanine formation detected by immunohistochemistry. In the cases of CD44- and/or OV6-positive tissue, no significant difference was observed. Cholangiocarcinoma patients with CD133- and/or Oct3/4-positive tumor tissues showed significantly lower expression of Mn-SOD and higher DDR protein, γ-H2AX. Moreover, CD133- and/or Oct3/4-positive cholangiocarcinoma patients had significant associations with tumor histology types, tumor stage, and poor prognoses. Our results suggest that CD133 and Oct3/4 in cholangiocarcinoma are associated with increased formation of DNA lesions and the DDR protein, which may be involved in genetic instability and lead to cholangiocarcinoma development with aggressive clinical features.

Topics: 8-Hydroxy-2'-Deoxyguanosine; AC133 Antigen; Albumins; Antigens, CD; Antigens, Differentiation; Bile Duct Neoplasms; Bile Ducts, Intrahepatic; Cell Transformation, Neoplastic; Cholangiocarcinoma; Cholangitis, Sclerosing; Deoxyguanosine; DNA Damage; DNA Repair; Female; Genomic Instability; Glycoproteins; Guanine; Histones; Humans; Hyaluronan Receptors; Inflammation; Keratin-19; Liver; Male; Middle Aged; Octamer Transcription Factor-3; Oxidation-Reduction; Peptides; Polycomb Repressive Complex 1; Prognosis; Stem Cells; Superoxide Dismutase

Ras mutation is important for carcinogenesis. Carcinogenesis consists of multi-step process with mutations in several genes. We investigated the role of DNA damage in carcinogenesis initiated by K-ras mutation, using conditional transgenic mice. Immunohistochemical analysis revealed that mutagenic 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) were apparently formed in adenocarcinoma caused by mutated K-ras. 8-Nitroguanine was co-localized with iNOS, eNOS, NF-κB, IKK, MAPK, MEK, and mutated K-ras, suggesting that oncogenic K-ras causes additional DNA damage via signaling pathway involving these molecules. It is noteworthy that K-ras mutation mediates not only cell over-proliferation but also the accumulation of mutagenic DNA lesions, leading to carcinogenesis.

Topics: Adenocarcinoma; Animals; Cell Proliferation; Cell Transformation, Neoplastic; DNA Damage; Genes, ras; Guanine; Mice; Mutation; Nitric Oxide Synthase Type II; Oxidative Stress

To investigate whether mutant stem cells participate in inflammation-related carcinogenesis, we performed immunohistochemical analysis to examine nitrative and oxidative DNA lesions (8-nitroguanine and 8-oxodG) and a stem cell marker Oct3/4 in bladder tissues obtained from cystitis and bladder cancer patients infected with Schistosomahaematobium (S. haematobium). We also detected the expression of nuclear factor-κB (NF-κB) and inducible nitric oxide synthase (iNOS), which lead to 8-nitroguanine formation. The staining intensity of 8-nitroguanine and 8-oxodG was significantly higher in bladder cancer and cystitis tissues than in normal tissues. iNOS expression was colocalized with NF-κB in 8-nitroguanine-positive tumor cells from bladder cancer patients. Oct3/4 expression was significantly increased in cells from S. haematobium-associated bladder cancer tissues in comparison to normal bladder and cancer tissues without infection. Oct3/4 was also expressed in epithelial cells of cystitis patients. Moreover, 8-nitroguanine was formed in Oct3/4-positive stem cells in S. haematobium-associated cystitis and cancer tissues. In conclusion, inflammation by S.haematobium infection may increase the number of mutant stem cells, in which iNOS-dependent DNA damage occurs via NF-κB activation, leading to tumor development.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Cell Transformation, Neoplastic; Cystitis; Deoxyguanosine; DNA Damage; Guanine; Humans; Neoplastic Stem Cells; NF-kappa B; Nitric Oxide Synthase Type II; Octamer Transcription Factor-3; Schistosoma haematobium; Schistosomiasis haematobia; Urinary Bladder Neoplasms