Shinya Toyokuni

DNA of cancers such as renal cell carcinoma and mammary invasive ductal carcinoma, is persistently exposed to more oxidative stress than that of adjacent normal tissue. We suggest that the concept of 'persistent oxidative stress in cancer' may open up a new research area, explaining part of the characteristic tumor biology of cancer such as activated transcription factors and proto-oncogenes, genomic instability, chemotherapy-resistance, invasion and metastasis.

The DNA base-modified product 8-hydroxy-2'-deoxyguanosine (8-OHdG) is one of the most commonly used markers for the evaluation of oxidative DNA damage. A monoclonal antibody specific for 8-OHdG (N45.1) was characterized and applied in quantitative immunohistochemistry. N45.1 recognized both the modified base and deoxyribose structure of 8-OHdG and required a concentration two orders higher of 8-hydroxyguanosine as a competitor in the ELISA. In addition, N45.1 did not cross-react with the origina

Iron is abundant universally. During the evolutionary processes, humans have selected iron as a carrier of oxygen inside the body. However, iron works as a double-edged sword, and its excess is a risk for cancer, presumably via generation of reactive oxygen species. Thus far, pathological conditions such as hemochromatosis, chronic viral hepatitis B and C, exposure to asbestos fibers, as well as endometriosis have been recognized as iron overload-associated risks for human cancer. Indeed, iron i

Recent studies have clarified that reactive oxygen species (ROS) are involved in a diversity of biological phenomena including radiation damage, carcinogenesis, ischemia-reperfusion injury, diabetes mellitus and neurodegenerative diseases. The breakthrough of these fruitful accomplishments was the discovery of an enzyme, superoxide dismutase, by McCord and Fridovich in 1968. In the 1970s and 80s, biochemists and radiation biologists were attracted by the role of ROS in its irreversible damage to

An iron chelate, ferric nitrilotriacetate (Fe-NTA), induces proximal tubular necrosis, a consequence of lipid peroxidation, that finally leads to a high incidence of renal adenocarcinoma in rodents. Lipid peroxidation as monitored by formation of thiobarbituric acid-reactive substances and free 4-hydroxy-2-nonenal (HNE) was observed in the kidney homogenates of rats treated with Fe-NTA. Based on the fact that HNE is capable of reacting with cellular proteins, we attempted to detect the localizat

Ratios of urinary 8-hydroxy-2'-deoxyguanosine to urinary creatinine (8-OHdG/creatinine) have been considered as a good biological indicator of DNA oxidation. Urinary 8-OHdG/creatinine levels of lung cancer patients were evaluated by enzyme-linked immunosorbent assay using a monoclonal antibody N45.1 during radiotherapy and chemotherapy. An increase in urinary 8-OHdG/creatinine was found in non-small-cell carcinoma (non-SCC) patients during the course of radiotherapy. SCC patients showed higher l

Monoclonal antibodies directed against proteins modified with the major membrane lipid peroxidation product, 4-hydroxy-2-nonenal, have been established and characterized. The monoclonal antibodies specific for HNE-modified proteins were raised by immunizing mice with a HNE-keyhole limpet hemocyanin conjugate. The resulting five monoclonal antibodies (mAbs HNEJ-1-5) recognized HNE-modified bovine serum albumin (BSA), but not native BSA in Western blot studies. Of the five mAbs, HNEJ-2 exhibited t

Reactive oxygen species (ROS) have been shown to be associated with a wide variety of pathological phenomena such as carcinogenesis, inflammation, radiation and reperfusion injury. Iron, the most abundant transition metal ion in our body, may work as a catalyst for the generation of ROS in pathological conditions. In the past few years, there have been great advances in the understanding of iron metabolism. These include the discoveries of iron transporters and the gene responsible for hereditar

To study the possible involvement of reactive oxygen species (ROS) in the tumor biology of human renal-cell carcinoma (RCC), we analyzed 35 cases of RCC for 2 parameters of oxidative damage: 8-hydroxy-2'-deoxyguanosine (8-OHdG), a mutation-prone DNA-base-modified product, was measured by means of high-performance liquid chromatography (HPLC) with an electrochemical (EC) detector, and 4-hydroxy-2-nonenal (HNE)-modified proteins were measured with a polyclonal antibody against HNE-modified protein

Ferric nitrilotriacetate (Fe-NTA) causes renal proximal tubular necrosis, a consequence of iron ion-mediated free-radical-associated damage, that finally leads to a high incidence of renal adenocarcinoma in male rats and mice. We have investigated the levels of typical hydroxyl radical-induced DNA base modifications in renal chromatin of male Wistar rats treated with a single or repeated administrations of Fe-NTA. Five pyrimidine-derived and 5 purine-derived modified DNA bases were identified an

Hypoxia and acidity provide microenvironment for selection under evolutionary pressure and proliferation in cancer cells. Carbonic anhydrases (CAs) are a superfamily of metalloenzymes present in all life kingdoms, equilibrating the reactions among CO₂, bicarbonate and H⁺. CA9, a membrane-associated α-CA, has been a drug target for various cancers. Whereas iron is essential not only for cancer cells but also for all the lives on earth, little is known on the association amon

Respiratory exposure to asbestos fibers has been associated with diffuse malignant mesothelioma (DMM) in humans. Despite advancements in the molecular analyses of human DMM and the development of animal models, the carcinogenic mechanisms of the disease remain unclear. There are basically three hypotheses regarding the pathogenesis of asbestos-induced DMM, which may be summarized as follows: (1) the "oxidative stress theory" is based on the fact that phagocytic cells that engulf asbestos fibers