Lessons from Basic Research in Selenium and Cancer Prevention

Ip, Clement

doi:10.1093/jn/128.11.1845

Cited by 627 publications

(515 citation statements)

References 64 publications

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“…1. The main pathway for the assimilation of Se intake was first proposed by Ip 36 and consists of the reduction of the different species to hydrogen selenide (HSe À ). This species plays the role of a central gateway for both utilization and excretion of Se.…”

Section: Absorption and Metabolismmentioning

confidence: 99%

Selenium biochemistry and its role for human health

Roman¹,

Jitaru²,

Barbante³

2014

Metallomics

652

451

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Despite its very low level in humans, selenium plays an important and unique role among the (semi)metal trace essential elements because it is the only one for which incorporation into proteins is genetically encoded, as the constitutive part of the 21st amino acid, selenocysteine. Twenty-five selenoproteins have been identified so far in the human proteome. The biological functions of some of them are still unknown, whereas for others there is evidence for a role in antioxidant defence, redox state regulation and a wide variety of specific metabolic pathways. In relation to these functions, the selenoproteins emerged in recent years as possible biomarkers of several diseases such as diabetes and several forms of cancer. Comprehension of the selenium biochemical pathways under normal physiological conditions is therefore an important requisite to elucidate its preventing/therapeutic effect for human diseases. This review summarizes the most recent findings on the biochemistry of active selenium species in humans, and addresses the latest evidence on the link between selenium intake, selenoproteins functionality and beneficial health effects. Primary emphasis is given to the interpretation of biochemical mechanisms rather than epidemiological/observational data. In this context, the review includes the following sections: (1) brief introduction; (2) general nutritional aspects of selenium; (3) global view of selenium metabolic routes; (4) detailed characterization of all human selenoproteins; (5) detailed discussion of the relation between selenoproteins and a variety of human diseases.

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Section: Absorption and Metabolismmentioning

confidence: 99%

Selenium biochemistry and its role for human health

Roman¹,

Jitaru²,

Barbante³

2014

Metallomics

652

451

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“…Animal experiments on initiation, promotion and proliferation of tumors tended to support a beneficial effect of selenium. In animal experiments, however, individual selenium compounds differed in their efficacy (Ip and Ganther, 1990;Ip, 1998). The protective effect of selenium is not readily explained in terms of prevention of oxidative DNA damage, since, as a rule, higher dosages of selenium than those optimizing peroxide metabolism are required (Combs et al, 1997;Combs and Gray, 1998;Ganther, 1999).…”

Section: Selenium and Tumor Incidencementioning

confidence: 99%

Selenium in Biology: Facts and Medical Perspectives

Köhrl¹,

Brigelius‐Flohé²,

Böck³

et al. 2000

Biological Chemistry

247

143

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Several decades after the discovery of selenium as an essential trace element in vertebrates approximately 20 eukaryotic and more than 15 prokaryotic selenoproteins containing the 21 st proteinogenic amino acid, selenocysteine, have been identified, partially characterized or cloned from several species. Many of these proteins are involved in redox reactions with selenocysteine acting as an essential component of the catalytic cycle. Enzyme activities have been assigned to the glutathione peroxidase family, to the thioredoxin reductases, which were recently identified as selenoproteins, to the iodothyronine deiodinases, which metabolize thyroid hormones, and to the selenophosphate synthetase 2, which is involved in selenoprotein biosynthesis. Prokaryotic selenoproteins catalyze redox reactions and formation of selenoethers in (stress-induced) metabolism and energy production of E. coli, of the clostridial cluster XI and of other prokaryotes. Apart from the specific and complex biosynthesis of selenocysteine, selenium also reversibly binds to proteins, is incorporated into selenomethionine in bacteria, yeast and higher plants, or posttranslationally modifies a catalytically essential cysteine residue of CO dehydrogenase. Expression of individual eukaryotic selenoproteins exhibits high tissue specificity, depends on selenium availability, in some cases is regulated by hormones, and if impaired contributes to several pathological conditions. Disturbance of selenoprotein expression or function is associated with deficiency syndromes (Keshan and Kashin-Beck disease), might contribute to tumorigenesis and atherosclerosis, is altered in several bacterial and viral infections, and leads to infertility in male rodents.

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“…In particular monomethylselenol and its precursorsmethyl-selenocysteine(Se-MeSeCys)andR-glutamylderivatives have been suggested to be the key anticarcinogenic Se species (18)(19)(20). To date, speciation of Se in rice has not been investigated with in situ techniques such as X-ray absorption near edge structure (XANES).…”

Section: Introductionmentioning

confidence: 99%

Selenium Characterization in the Global Rice Supply Chain

Williams

Lombi

Sun

et al. 2009

Environ. Sci. Technol.

195

133

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For up to 1 billion people worldwide, insufficient dietary intake of selenium (Se) is a serious health constraint. Cereals are the dominant Se source for those on low protein diets, as typified by the global malnourished population. With crop Se content constrained largely by underlying geology, regional soil Se variations are often mirrored by their locally grown staples. Despite this, the Se concentrations of much of the world's rice, the mainstay of so many, is poorly characterized, for both total Se content and Se speciation. In this study, 1092 samples of market sourced polished rice were obtained. The sampled rice encompassed dominant rice producing and exporting countries. Rice from the U.S. and India were found to be the most enriched, while mean average levels were lowest in Egyptian rice: ∼32-fold less than their North American equivalents. By weighting country averages by contribution to either global production or export, modeled baseline values for both were produced. Based on a daily rice consumption of 300 g day -1 , around 75% of the grains from the production and export pools would fail to provide 70% of daily recommended Se intakes. Furthermore, Se localization and speciation characterization using X-ray fluorescence (µ-XRF) and X-ray absorption near edge structure (µ-XANES) techniques were investigated in a Se-rich sample. The results revealed that the large majority of Se in the endosperm was present in organic forms.

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Lessons from Basic Research in Selenium and Cancer Prevention

Cited by 627 publications

References 64 publications

Selenium biochemistry and its role for human health

Selenium biochemistry and its role for human health

Selenium in Biology: Facts and Medical Perspectives

Selenium Characterization in the Global Rice Supply Chain

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