For a review see
Metal passivity as mechanism of metal carcinogenesis: Chromium, nickel, iron, copper, cobalt, platinum, molybdenum, CORNELIA RICHARDSON-BOEDLER Toxicological & Environmental Chemistry, Jan–Mar 2007; 89(1): 15–70.
There are indications of a relationship between molybdenum deficiency and the development of various tumours. The incidence of oesophageal cancer in areas of South Africa varies depending on location [Davies, 1975; Rose, 1968; Burrell et al., 1966]. The gardens of a group of Bantu women who died of cancer were less fertile and less productive than those of tumour-free women. Severe signs of molybdenum deficiency were noted in plants grown in gardens of the cancer sufferers. It is suggested that the molybdenum deficiency resulted in the plants being more prone to attack by fungi, e.g. Aspergillus flavus, which has been implicated as a cause of liver cancer in animals. The distribution of molybdenum in mouse liver and Sarcoma 180 was determined following the intraperitoneal injection daily for 6 d of various molybdenum compounds [Caruthers and Regelson, 1963]. With Na4SiMol2O40, MoCl5, and MoBr2 there was an accumulation of molybdenum in the liver and the tumour but with (NH4)6Mo7O24.4H2O and Mo3(H2C2O4).2H2O there was no such accumulation. The copper and zinc contents of the liver and the tumour were not affected by any of the molybdenum compounds nor was the growth rate of the tumour. It is possibly relevant that the concentration of xanthine oxidase is relatively low in various tumours and that tumour growth in mice was decreased by treatment with xanthine oxidase concentrates [Bray, 1963].
Davies, I. J. T., Intake (British Medical Journal. Advertiser's Supplement), 1975, 39, 4.
Rose, E. F., Cancer Research, 1968, 28, 2390.
Burrell, R. J. W., Roach, W. A. and Shadwell, A., J. Nat. Cancer Inst., 1966, 36, 201, 211.
Caruthers C.and Regelson, W.,Oncologia, 1963, 16, 101.
Bray, R. C., in The Enzymes, ed. Boyer, P. D., Hardy, L. and Myrback, K., Academic Press, New York, 2nd Edn., 1963, 7, 533.
Two randomised nutrition intervention trials were conducted in Linxian, an area of north central China with some of the world's highest rates of oesophageal and stomach cancer and a population with a chronically low intake of several nutrients. to assess the effects in nearly 30 000 participants of daily supplementation with: retinol and zinc; riboflavin and niacin; vitamin C and molybdenum; and beta-carotene, alpha-tocopherol, and selenium. The second trial provided daily multiple vitamin-mineral supplementation; or placebo in 3318 persons with oesophageal dysplasia, a precursor to oesophageal cancer. After supplements were given for 5.25 y in the general population trial, small but significant reductions in total relative risk [(RR) = 0.91] and cancer (RR = 0.87) mortality were observed in subjects receiving beta-carotene, alpha-tocopherol, and selenium but not the other nutrients. The largest reductions were for cerebrovascular disease mortality, but the effects differed by sex: a significant reduction was observed in men (RR = 0.45) but not women (RR = 0.90).Restoring adequate intake of certain nutrients may help to lower the risk of cancer and other diseases in this high-risk population [Blot et al., 1995].
Blot, W.J., Li, J.Y., Taylor, P.R., Guo, W.D., Dawsey, S.M., Li, B.,. The Linxian Trials - Mortality-Rates By Vitamin-Mineral Intervention Group, American Journal Of Clinical Nutrition,1995, 62, S1424-S1426.
Xanthine dehydrogenase (EC 220.127.116.11) is a molybdenum iron-sulfur, flavin hydroxylase involved in purine catabolism. Xanthine dehydrogenase-induces activation of bioreductive agents including chemotherapeutic agents requiring bioreductive activation for their antineoplastic activities. Xanthine dehydrogenase is potentially important as an enzyme targeted in chemotherapeutic regimens is discussed [Pritsos et al., 1994].
Pritsos, C.A., Gustafson, D.l., Xanthine Dehydrogenase And Its Role In Cancer-Chemotherapy, Oncology Research, 1994, 6, 477-481.
The antitumor active molybdocene dichloride Cp2MoCl2 formed two stable adducts at pD 6 which were tentatively assigned as a Cp2Mo-glutathione chelate involving coordination of the cysteine thiol and glycine carboxylate to the molybdenum centre, and a thiol centred 1:2 Cp2Mo-glutathione complex. The implications for the mechanism of antitumor action of the metallocene dihalides are discussed.
Mokdsi, G. and Harding, M. M., A H-1 NMR study of the interaction of antitumor metallocenes with glutathione, Journal of Inorganic Biochemistry, 2001, 86, 611-616.
Interest in the aqueous, bio-organometallic chemistry of metallocene dihalides has stemmed from the potent antitumor properties of titanocene dichloride, including results from human clinical trials. Key results on the biological chemistry of molybdocene dichloride are reviewed. Under physiological conditions the positively charged monoaquated species Cp2Mo(OH)(OH2)+, in equilibrium with the dipositively charged dimer Cp2Mo(mu-OH)2MoCp2, is present.Studies of the coordination chemistry of Cp2MoCl2 with nucleobases, nucleotides, single-stranded and double-stranded oligonucleotides, and calf-thymus DNA have shown that, while simultaneous phosphate(O) and heterocyclic(N) adducts are formed with nucleotides, negligible interaction with DNA occurs under physiological conditions. Cp2MoCl2 forms strong, non-labile complexes with deprotonated thiols in amino acids. Molybdocene dichloride is able to catalyse the hydrolysis of activated phosphate esters under physiological conditions, but hydrolysis of unactivated phosphodiesters is only significant at pH 4. Limited antitumor activity results, inhibition studies with protein kinase C and topoisomerase II, structure-activity and cell-uptake studies have provided some insight into possible mechanisms of antitumor action.
Waern, J.B. and Harding, M. M., Bioorganometallic chemistry of molybdocene dichloride, Journal of Organometallic Chemistry, 2004, 689, 4655-4668.
The compounds molybdenocene dichloride (Cp2MoCl2) and [Cp2Mo(L)(n)]Cl2 (n = 1, L = 6-mercaptopurine, 6- mercaptopurineribose, 2-amine-6-mercaptopurine and 2-amine-6- mercaptopurineribose and n = 2, L = D-penicillamine) have antitumour properties. Their complexes with calfthymus DNA have been investigated by cyclic voltammetry. (Cp2MoCl2) and [Cp2Mo(L)(n)]Cl2 (n = 1, L = 2-amine-6- mercaptopurine and 2-amine-6-mercaptopurineribose and n = 2, L = D-penicillamine) complexes showed weak DNA bindings (3.2- 10.1%) while the complexes containing the ligands 6- mercaptopurine and 6-mercaptopurineribose showed negligible interactions.
Rodriguez, M.I., Chavez-Gil, T., Colon, Y., Diaz, N., and Melendez, E., Molybdenocene-DNA interaction studies using electrochemical analysis, Journal of Electroanalytical Chemistry, 2005, 576, 315-322.