The role of iron in cancer.

[James]

Eur J Cancer Prev. 1996 Feb;5(1):19-36.

The role of iron in cancer.

Weinberg ED.

Abstract

Numerous laboratory and clinical investigations over the past few decades have observed that one of the dangers of iron is its ability to favour neoplastic cell growth. The metal is carcinogenic due to its catalytic effect on the formation of hydroxyl radicals, suppression of the activity of host defence cells and promotion of cancer cell multiplication. In both animals and humans, primary neoplasms develop at body sites of excessive iron deposits. The invaded host attempts to withhold iron from the cancer cells via sequestration of the metal in newly formed ferritin. The host also endeavours to withdraw the metal from cancer cells via macrophage synthesis of nitric oxide. Quantitative evaluation of body iron and of iron-withholding proteins has prognostic value in cancer patients. Procedures associated with lowering host iron intake and inducing host cell iron efflux can assist in prevention and management of neoplastic diseases. Pharmaceutical methods for depriving neoplastic cells of iron are being developed in experimental and clinical protocols.

[James]

Biol Trace Elem Res. 1992 Aug;34(2):123-40.

Roles of iron in neoplasia. Promotion, prevention, and therapy.

Weinberg ED.

Abstract

Research and clinical observations during the past six decades have shown that: 1. Iron promotes cancer cell growth; 2. Hosts attempt to withhold or withdraw iron from cancer cells; and 3. Iron is a factor in prevention and in therapy of neoplastic disease. Although normal and neoplastic cells have similar qualitative requirements for iron, the neoplastic cells have more flexibility in acquisition of the metal. Excessive iron levels in animals and humans are associated with enhanced neoplastic cell growth. In invaded hosts, cytokine-activated macrophages increase intracellular ferritin retention of the metal, scavenge iron in areas of tumor growth, and secrete reactive nitrogen intermediates to effect efflux of nonheme iron from tumor cells. Procedures associated with lowering host intake of excess iron can assist in prevention and in management of neoplastic disease. Chemical methods for prevention of iron assimilation by neoplastic cells are being developed in experimental and clinical protocols. The antineoplastic activity of a considerable variety of chemicals, as well as of radiation, is modulated by iron. The present article focuses on recent findings and suggests directions for further cancer-iron research.

[James]

Cancer Sci. 2009 Jan;100(1):9-16. doi: 10.1111/j.1349-7006.2008.01001.x. Epub 2008 Oct 23.

Role of iron in carcinogenesis: cancer as a ferrotoxic disease.

Toyokuni S.

Abstract

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 is carcinogenic in animal experiments. These reports unexpectedly revealed that there are target genes in iron-induced carcinogenesis and that iron-catalyzed oxidative DNA damage is not random in vivo. Several iron transporters and hepcidin, a peptide hormone regulating iron metabolism, were discovered in the past decade. Furthermore, a recent epidemiological study reported that iron reduction by phlebotomy decreased cancer risk in the apparently normal population. These results warrant reconsideration of the role of iron in carcinogenesis and suggest that fine control of body iron stores would be a wise strategy for cancer prevention.

[James]

Curr Med Chem. 2003 Jun;10(12):1035-49.

Iron chelators as anti-neoplastic agents: current developments and promise of the PIH class of chelators.

Lovejoy DB, Richardson DR.

Abstract

The chelator currently used to treat iron (Fe) overload disease, desferrioxamine (DFO), has shown anti-proliferative activity against leukemia and neuroblastoma cells in vitro, in vivo and in clinical trials. Collectively, these studies suggest that Fe-deprivation may be a useful anti-cancer strategy. However, the efficacy of DFO is severely limited due to its poor ability to permeate cell membranes and bind intracellular Fe pools. These limitations have encouraged the development of other Fe chelators that are far more effective than DFO. One group of ligands that have been extensively investigated are those of the pyridoxal isonicotinoyl hydrazone (PIH) class. In this review the marked anti-proliferative effects of the PIH analogs are discussed with reference to their mechanisms of action and structure-activity relationships. In particular, we discuss the activity of a novel group of ligands that are "hybrid" chelators derived from our most effective PIH analogs and thiosemicarbazones. The anti-tumor activity of the PIH analogs and other chelators such as tachpyridine, O-trensox and the desferrithiocin analogs have been well characterized in vitro. However, further studies in animals are critical to evaluate their selective anti-tumor activity and potential as therapeutic agents.