Fanconi syndrome

An extensive body of evidence has demonstrated the sensitivity of Fanconi anemia (FA) cells to redox-active xenobiotics, such as mitomycin C, diepoxybutane, cisplatin, and 8-methoxypsoralen plus ultraviolet irradiation, with toxicity mechanisms that are consistent with a deficiency of FA cells in coping with oxidative stress. A recent study has reported on excess sensitivity of FA complementation A group cells to chromium VI [Cr(VI)] toxicity, by postulating that a deficiency in Cr-DNA cross-link removal by FA cells and formation of Cr(VI)-associated cross-links may be the mechanism of Cr(VI)-induced cytotoxicity. However, the report failed to demonstrate any enhanced Cr uptake or, especially, any increase in Cr-DNA adducts. Thus, well-established findings on Cr(VI)-induced oxidative stress may explain excess sensitivity of FA cells to Cr(VI) in terms of its inability to cope with the Cr(VI)-induced prooxidant state. Key words: chromium, cisplatin, diepoxybutane, DNA adducts, Fanconi anemia, 8-hydroxy-2'-deoxyguanosine, 8-methoxypsoralen, mitomycin C, oxidative stress. Environ Health Perspect 111:1699-1703 (2003). doi:10.1289/ehp.6229 available via http://dx.doi.org/[Online 12 June 2003]

**********

A number of organic and inorganic xenobiotics exert their toxicity via a sequence of mechanisms that relate to redox-related biotransformation (Bagchi et al. 2002; Balamurugan et al. 2002; Dusre et al. 1990; Ercal et al. 2001; Penketh et al. 2001; Quievryn et al. 2001; Sawamura et al. 1996; Seaton et al. 1995). These mechanisms include a number of distinct events that may result in direct oxidative damage, such as the formation of reactive oxygen species (ROS), the occurrence of redox couples {e.g., chromium [Cr(VI)/Cr(III)]}, and the formation of reactive intermediates of the native molecule (Dusre et al. 1990; Ercal et al. 2001; Gutteridge et al. 1984; Pagano 2002; Stohs and Bagchi 1995). As a possible alternative, the action mechanisms of some xenobiotics may interfere with some essential antioxidant systems, for example, the glutathione (GSH) system, thus resulting in a redox imbalance (Spano et al. 1998; Vlachodimitropoulos et al. 1997).

In many instances, a combination of effects may occur, for example, related to a) ROS activity, b) modulation of redox-related activities and/or of thiol antioxidants, and/or c) the specific action of xenobiotic end product(s) (e.g., cross-linking with biopolymers) (Pagano 2002). The mechanistic features for any class of agents imply the extent to which these events may prevail, also depending on the individual structure analogs being considered, as well as other factors related to extra--and intracellular environment, for example, ambient oxygen levels, the endogenous redox-related activities, pH and other ionic balance, and the co-presence of other bioactive agents (hormones or other xenobiotics).

A set of xenobiotics has been reported to exert enhanced toxicity to cells from patients with Fanconi anemia (FA), a cancer-prone genetic disease (Ahmad et al. 2002; Alter 1996; Auerbach et al. 1998). The excess sensitivity of FA cells is used in FA diagnosis and is commonly attributed to the inability of FA cells to repair DNA cross-links induced by these agents. This subject has direct implications in disease definition, because the axiom of "cross-linker sensitivity" is related to the widespread opinion that FA is a DNA repair deficiency syndrome. In this commentary we review the published evidence for the involvement of several (and distinct) redox-related mechanisms in the toxicities of all the xenobiotics that have been reported to trigger enhanced sensitivity in FA cells, and we discuss the role for cross-link formation and removal.

Xenobiotics Involved in Defining FA Phenotype

Mitomycin C. Since the report by Iyer and Szybalski (1964), the requirement for redox biotransformation of mitomycin C (MMC) has been well recognized in pharmacology, because MMC must be activated by a series of redox reactions leading to semiquinone derivatives coupled with ROS formation (Dusre et al. 1990; Gutteridge et al. 1984; Penketh et al. 2001; Pritsos and Sartorelli 1986). Well-established mechanistic information has shown that MMC-associated toxicity is dependent on oxygen levels (Clarke et al. 1997; Korkina et al. 2000) and is removed by low-molecular-weight antioxidants (Raj and Heddle 1980) and by thioredoxin (Trx) overexpression (Ruppitsch et al. 1998). Recent reports demonstrate that a) MMC exposure results in an increase in oxidative DNA damage (Pagano et al. 2001); b) FA cells fail to accumulate higher MMC adduct levels in DNA than control cells (Rutherford et al. 1999; Will et al. 1998); and c) the ratio of MMC biadducts to monoadducts (reflective of a DNA repair defect) shows no difference in FA cells compared with normal cells (Rutherford et al. 1999). In a previous study, Clarke et al. (1997) had shown that MMC-induced apoptosis in FA complementation group C (FA-C) cells occurred under normoxic conditions (associated with redox-cycling mechanisms), whereas MMC was ineffective in causing apoptosis under hypoxic conditions (with prevailing cross-link formation).

Diepoxybutane. Diepoxybutane (DEB) toxicity may be indirectly associated with redox mechanisms because its epoxide structure implies susceptibility to GSH scavenging (Bartok and Ling 1980). Similar to MMC, DEB-associated toxicity correlates with oxygen levels (Korkina et al. 2000) and oxidative DNA damage (Pagano et al. 2001), whereas DEB-induced cytotoxicity and DNA damage are decreased by Trx overexpression (Ruppitsch et al. 1998). DEB toxicity is modulated by GSH, and in turn, DEB results in GSH depletion (Korkina et al. 2000; Spano et al. 1998; Vlachodimitropoulos et al. 1997). Thus, a major feature of DEB-induced toxicity may be related to an imbalance in GSH levels resulting in a cellular prooxidant state.

Cisplatin. After the early report by Poll et al. (1982) showing excess sensitivity of FA cells to platinum compounds, cisplatin (CDDP)--associated toxicity has been regarded as an example of cross-linkers exerting enhanced toxicity to FA cells (Auerbach et al. 1998). Further studies, however, have provided mechanistic evidence for CDDP biotransformation leading to oxidative stress along with a cascade of redox-associated events. It has been recognized that oxidative pathways participate in the characteristic nephrotoxicity of CDDP, including induction of heme oxygenase-1 (Schaaf et al. 2002), and CDDP-induced cytotoxicity and ROS formation are effectively counteracted by antioxidants such as alpha-tocopherol, vitamin C, and N-acetylcysteine (NAC) (De Martinis and Bianchi 2001; Schaaf et al. 2002). Treatment of myeloma cells with NAC completely blocked CDDP-dependent intracellular GSH oxidation, ROS generation, poly(ADP-ribose) polymerase cleavage, and apoptosis (Godbout et al. 2002). Bauman et al. (1991) reported a protective role of metallothionein, a scavenger of hydroxyl radicals, against a number of oxidative stress-associated xenobiotics, including CDDP.

Waisfisz et al. (2002) have demonstrated that [p21.sup.waf1/Cip1] an oxidative stress regulatory gene (Esposito et al. 1998), is overexpressed in lymphoblastoid FA cells and is very sensitive to CDDP. [p21.sup.waf1/Cip1] is known to be a key regulator of G1 cell-cycle arrest and has been recently linked to G2 cell-cycle regulation (Taylor and Stark 2001). This observation fits well with the previously observed up-regulation of apoptotic regulatory p53 protein and cyclin B proteins, inactivation of CDC2 kinase, and cell-cycle arrest, which follows exposure to low doses of cross-linking agents in FA cells (Kruyt et al. 1996, 1997; Kupfer and D'Andrea 1996). Also p53, cyclin B, and CDC2 kinase are known to be involved in oxidative stress pathways (Barnouin et al. 2002; Chen et al. 2002; Chuang et al. 2002).

Hence, the literature provides cellular and molecular evidence for a direct involvement of redox pathways in CDDP-associated toxicity mechanisms.

8-Methoxypsoralen and ultraviolet A. Early studies pointed to the excess sensitivity of FA cells to 8-methoxypsoralen (8-MOP) plus ultraviolet A (UVA) irradiation (PUVA), and the results were construed as due to inability to cope with 8-MOP cross-link formation (Moustacchi and Diatloff-Zito 1985). The combination of PUVA, however, is associated with production of ROS that react subsequently with DNA, lipids, and proteins and cause a decrease in cellular antioxidative capacity (Reinheckel et al. 1999). Both UVA irradiation and PUVA treatment induced significant changes in the distribution of arachidonic acid and increased the liberation of arachidonic acid from membrane phospholipids, with a significant increase in the formation of thiobarbituric acid-reactive material. The activities of the antioxidant enzymes catalase and superoxide dismutase were also significantly decreased by UVA (Punnonen et al. 1991). PUVA-associated toxicity has been shown to cause GSH depletion (d'Ischia et al. 1989), which in turn involves an oxidative stress condition.

Chromium (VI). In a recent article, Vilcheck et al. (2002) reported on excess sensitivity of FA complementation A group (FA-A) cells to Cr(VI)-induced toxicity and apoptosis. Cell growth and apoptosis were measured by phosphatidylserine translocation and caspase-3 activation. Both the induction of apoptosis and of clonogenicity showed significantly increased sensitivity to Cr(VI) in FA-A cells versus control fibroblasts. However, no increase in Cr(VI) uptake or in Cr-DNA adducts was detected in FA-A cells versus control cells.

Vilcheck et al. (2002) relied on the assumptions that FA phenotype and Cr-associated toxicity should be based on a) excess sensitivity to DNA cross-linking agents, suggesting "a general defect in the repair of DNA cross-links" and b) the ultimate events in Cr-associated toxicity, namely, the formation of DNA lesions, such as DNA-Cr-DNA inter-strand cross-links (Bridgewater et al. 1998; Mattagajasingh and Misra 1999; O'Brien et al. 2001; Singh et al. 1998). However, this study provides support to the body of evidence relating oxidative stress both to FA phenotype and to Cr toxicity:

An extensive body of literature has provided evidence for the role of multiple redox-related events in Cr-associated toxicity, as summarized in Table 1. These events include both direct and indirect mechanisms related to oxidative stress, for example, Cr-induced depletion of GSH and other thiol-based antioxidants (Nguyen-nhu and Knoops 2002; O'Brien et al. 2001; Quievryn et al. 2001); protective effects of catalase, melatonin, or NAC (Cabrer et al. 2001; Izzotti et al. 1998; Shi et al. 1999); ROS formation (Bagchi et al. 2001; Hassoun and Stohs 1995; Izzotti et al. 1998; Tsou et al. 1996); nitric oxide production (Hassoun and Stohs 1995); and lipid peroxidation (Bagchi et al. 1995, 1997). The eventual formation of Cr adducts to DNA, or to proteins and DNA, may be viewed as an ultimate step in a set of redox-dependent mechanisms (Blasiak and Kowalik 2000; Hodges et al. 2001).

As shown in Tables 2 and 3, the xenobiotics commonly used in FA diagnosis (MMC, DEB), or otherwise associated with excess sensitivity in FA cells (CDDP, PUVA), display distinct mechanisms of toxicity that, however, involve redox-dependent actions interrelated with ROS formation and/or oxygen levels, and/or modulation of antioxidant levels, and/or antioxidant enzyme activities.

These mechanistic features, conversely, may suggest a redox imbalance in FA cells, as far as they display a prooxidant state making them unable to cope with prooxidant xenobiotics.

Prooxidant State in FA Phenotype

FA is a genetic disorder associated with bone marrow failure, chromosomal instability, and poor prognosis (Alter 1996; Auerbach et al. 1998). FA shows a progression to aplastic anemia, excess risk of malignancy (mainly nonlymphocytic leukemia), a set of typical malformations, and altered skin pigmentation. A total of eight complementation groups have been identified, and six genes (FANCA, FANCC, FANCD2, FANCE, FANGF, FANCG) have been cloned so far (Tamary et al. 2002). Diagnosis is performed by excess FA cell sensitivity to either DEB or MMC that induces high rates of chromosomal breaks (Auerbach and Wolman 1976). A line of molecular evidence has related at least two FA gene-encoded proteins with redox pathways. The protein encoded by the Fanconi gene C (FANCC) has been shown to associate with redox-related activities, namely, NADPH cytochrome P450 reductase (Kruyt et al. 1998) and glutathione S-transferase (Cumming et al. 2001). A recent study has provided evidence that the FANCG protein interacts with cytochrome P450 2E1 protein, an activity also known to be involved in redox biotransformation of xenobiotics (Futaki et al. 2002). Previous indirect evidence for an abnormal regulation of xenobiotic biotransformation in FA cells was provided by Joenje and Oostra (1986), who reported excess sensitivity of FA cells to cyclophosphamide without S-9 metabolic activation (Madle 1981). This finding suggested that FA cells, unlike non-FA cells, were endowed with a complete set of phase 1 activities for cyclophosphamide biotransformation.

The relationship of the FA phenotype with a prooxidant state was first suggested by Nordenson (1977). A consistent body of evidence has been accumulated since then, both related to phenotypic redox abnormalities and related to the involvement of FA proteins in redox pathways (Ahmad et al. 2002; Bogliolo et al. 2002; Pagano et al. 1998; Pagano and Korkina 2000; Pagano and Youssoufian 2003), as summarized in Table 4. FA cells are characterized by a) excess oxidative DNA damage [8-hydroxy-2'-deoxyguanosine (8-OHdG)] in hydrogen peroxide-exposed FA cells (Takeuchi and Morimoto 1993), and in freshly drawn white blood cells from FA patients (Degan et al. 1995); b) increased oxygen sensitivity (Joenje et al. 1981) and sensitivity to free iron (Poot et al. 1996); c) correction of chromosomal abnormalities by either antioxidant enzymes or by low-molecular-weight antioxidants (Dallapiccola et al. 1985; Nordenson 1977; Raj and Heddle 1980); d) excess plasma levels of clastogenic factor (Emerit et al. 1995) and of tumor necrosis factor-[alpha] (TNF-[alpha]; Dufour et al. 2003; Schulz and Shahidi 1993); e) involvement of redox-active cytokines, such as TNF-[alpha] and interferon-[gamma] (Dufour et al. 2003; Pearl-Yafe et al. 2003), and of inducible nitric oxide synthase (Hadjur and Jirik 2003); and d) an involvement of Trx, which corrects MMC and DEB sensitivity in FA cells (Ruppitsch et al. 1998) and occurs in lower-than-normal levels in FA fibroblasts (Kontou et al. 2002). Together, a well-established body of evidence on FA cellular phenotype, along with the roles for some FA proteins in redox pathways (Bogliolo et al. 2002; Pagano and Youssoufian 2003), combine to support a central role for oxidative stress both in FA cellular phenotype and in FA protein functions.

Conclusions and Suggestions

Well-established literature points to the involvement of redox-dependent mechanisms in the toxicity of MMC, DEB, CDDP, PUVA, and Cr(VI). The formation of DNA or protein-DNA cross-links may be viewed as the outcome of redox reactions coupled with ROS formation, antioxidant (e.g., GSH) depletion, and a multifaceted modulation of redox-related activities.

When these xenobiotics interact with FA cells, which are in turn characterized by a multiple prooxidant state, one should expect a more pronounced toxicity compared with control cells, due to FA cell deficiency in withstanding oxidative stress. At the same time, the failure to detect excess adduct formation after Cr(VI) (Vilcheck et al. 2002) or MMC (Rutherford et al. 1999) exposure does not support a deficiency in removing damaged DNA bases (i.e., in DNA repair).

In the same prospect, the use of FA cells may be envisioned in forthcoming studies designed to investigate the action mechanisms of redox-related environmental agents or pharmaceutical drugs.

REFERENCES

Ahmad SI, Hanaoka F, Kirk SH. 2002. Molecular biology of Fanconi anaemia--an old problem, a new insight. BioEssays 24:439-448.

Alter BP. 1996. Fanconi's anemia and malignancies. Am J Hematol 53:99-110.

Auerbach AD, Buchwald M, Joenje H. 1998. Fanconi anemia. In: The Genetic Basis of Human Cancer (Vogelstein B, Kinzier KW, eds). New York:Mcgraw-Hill, 317-322.

Auerbach AD, Wolman SR. 1976. Susceptibility of Fanconi's anaemia fibroblasts to chromosome damage by carcinogens. Nature 261:494-496.

Bagchi D, Bagchi M, Stohs SJ. 2001. Chromium (VI)-induced oxidative stress, apoptotic cell death and modulation of p53 tumor suppressor gene. Mol Cell Biochem 222:149-158.

Bagchi D, Balmoori J, Bagchi M, Ye X, Williams CB, Stohs SJ. 2002. Comparative effects of TCDD, endrin, naphthalene and chromium (VI) on oxidative stress and tissue damage in the liver and brain tissues of mice. Toxicology 175:73-82.

Bagchi O, Hassoun EA, Bagchi M, Stohs SJ. 1995. Chromium-induced excretion of urinary lipid metabolites, DNA damage, nitric oxide production, and generation of reactive oxygen species in Sprague-Dawley rats. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 110:177-187.

Bagchi D, Vuchetich P J, Bagchi M, Hassoun EA, Tran MX, Tang L, et al. 1997. Induction of oxidative stress by chronic administration of sodium dichromate [chromium VI] and cadmium chloride [cadmium II] to rats. Free Radic Biol Med 22:471-478.

Balamurugan K, Rajaram R, Ramasami T, Narayanan S. 2002. Chromium(III)-induced apoptosis of lymphocytes: death decision by ROS and Src-family tyrosine kinases. Free Radic Biol Med 33:1622-1640.

Barnouin K, Dubuisson ML, Child ES, Fernandez de Mattos S, Glassford J, Medema RH, et al. 2002. [H.sub.2][O.sub.2] induces a transient multi-phase cell cycle arrest in mouse fibroblasts through modulating cyclin D and p21Cip1 expression. J Biol Chem 277:13761-13770.

Bartok M, Lang KL. 1980. Oxiranes. In: The Chemistry of Ethers, Crown Ethers, Hydroxyl Groups and Their Sulphur Analogues (Patai S, ed). The Chemistry of Functional Groups Series, Supplement E, Part 2. Chichester, UK:John Wiley and Sons, 609-673.

Bauman JW, Liu J, Liu YP, Klaassen CD. 1991. Increase in metallothionein produced by chemicals that induce oxidative stress. Toxicol Appl Pharmacol 110:347-354.

Blasiak J, Kowalik J. 2000. A comparison of the in vitro genotoxicity of tri- and hexavalent chromium. Mutat Res 469:135-145.

Bogliolo M, Cabre 0, Callen E, Castillo V, Creus A, Marcos R, et al. 2002. The Fanconi anaemia genome stability and tumour suppressor network. Mutagenesis 17:529-538.

Bridgewater LC, Manning FC, Patierno SR. 1998. Arrest of replication by mammalian DNA polymerases alpha and beta caused by chromium-DNA lesions. Mol Carcinog 23:201-206.

Cabrer J, Burkhardt S, Tan DX, Manchester LC, Karbownik M, Reiter RJ. 2001. Autoxidation and toxicant-induced oxidation of lipid and DNA in monkey liver: reduction of molecular damage by melatonin. Pharmacol Toxicol 89:225-230.

Chen QM, Merrett JB, Dilley T, Purdom S. 2002. Down regulation of p53 with HPV E6 delays and modifies cell death in oxidant response of human diploid fibroblasts: an apoptosis-like cell death associated with mitosis. Oncogene 21:5313-5324.

Chuang YY, Chen Y, Gadisetti, Chandramouli GVR, Cook JA, Coffin D, et al. 2002. Gene expression after treatment with hydrogen peroxide, menadione, or t-butyl hydroperoxide in breast cancer cells. Cancer Res 62:6246-6254.

Clarke AA, Philpott NJ, Gordon-Smith EC, Rutherford TR. 1997. The sensitivity of Fanconi anaemia group C cells to apoptosis induced by mitomycin C is due to oxygen radical generation, not DNA crosslinking. Br J Haematol 96:240-247.

Cumming RC, Lightfoot J, Beard K, Youssoufian H, O'Brien P J, Buchwald M. 2001. Fanconi anemia group C protein prevents apoptosis in hematopoietic cells through redox regulation of GSTP1. Nature Med 7:814-820.

Dallapiccola B, Porfirio B, Mokini V, Alimena G, Isacchi G, Gandini E. 1985. Effect of oxidants and antioxidants on chromosomal breakage in Fanconi anemia lymphocytes. Hum Genet 69:62-65.

Degan P, Bonassi S, De Caterina M, Korkina LG, Pinto L, Scopacasa F, et al. 1995. In vivo accumulation of 8-hydroxy-2'-deoxyguanosine in DNA correlates with release of reactive oxygen species in Fanconi's anaemia families. Carcinogenesis 16:735-742.

De Martinis BS, Bianchi MD. 2001. Effect of vitamin C supplementation against cisplatin-induced toxicity and oxidative DNA damage in rats. Pharmacol Res 44:317-320.

d'lschia M, Napolitano A, Prota G. 1989. Psoralens sensitize glutathione photooxidation in vitro. Biochim Biophys Acta 993:143-147.

Dufour C, Corcione A, Svahn J, Haupt R, Poggi V, Nandor Bekassy A, et al. 2003. TNF-[alpha] and IFN-[gamma] are over expressed in the bone marrow of Fanconi anemia patients and TNF-[alpha] suppresses erythropoiesis in vitro. Blood 101 doi:10.1182/ blood-2003-01-0114 [Online 15 May 2003].

Dusre L, Rajagopalan S, Eliot HM, Covey JM, Sinha BK. 1990. DNA interstrand crosslink and free radical formation in a human multidrug resistant cell line from mitomycin C and its analogues. Cancer Res 50:648-652.

Emerit I, Levy A, Pagano G, Pinto L, Calzone R, Zatterale A. 1995. Transferable clastogenic activity in plasma from patients with FA. Hum Genet 96:14-20.

Ercal N, Gurer-0rhan H, Aykin-Burns N. 2001. Toxic metals and oxidative stress part I: mechanisms involved in metal-induced oxidative damage. Curr Top Med Chem 1:529-539.

Esposito F, Cuccovillo F, Russo L, Casella F, Russo T, Cimino F. 1998. A new [p21.sup.waf1/cip1] isoform is an early event of cell response to oxidative stress. Cell Death Differ 5:940-945.

Futaki M, Igarashi T, Watanabe S, Kajigaya S, Tatsuguchi A, Wang J, et al. 2002. The FANCG Fanconi anemia protein interacts with CYP2E1: possible role in protection against oxidative DNA damage. Carcinogenesis 23:67-72.

Godbout JP, Pesavento J, Hartman ME, Manson SR, Freund GG. 2002. Methylglyoxal enhances cisplatin-induced cytotoxicity by activating protein kinase C[delta]. J Biol Chem 277:2554-2561.

Gutteridge JMC, Quinlan GJ, Wilkins S. 1984. Mitomycin C-induced deoxyribose degradation inhibited by superoxide dismutase. A reaction involving iron, hydroxyl and semiquinone radicals. FEBS Lett 167:37-41.

Hadjur S, Jirik FR. 2003. Increased sensitivity of Fancc-deficient hematopoietic cells to nitric oxide and evidence that this species mediates growth inhibition by cytokines. Blood 101:3877-3884.

Hassoun EA, Stohs SJ. 1995. Chromium-induced production of reactive oxygen species, DNA single-strand breaks, nitric oxide production, and lactate dehydrogenase leakage in J774A.1 cell cultures. J Biochem Toxicol 10:315-321.

Hodges N J, Adam B, Lee A J, Cross H J, Chipman JK. 2001. Induction of DNA-strand breaks in human peripheral blood lymphocytes and A549 lung cells by sodium dichromate: association with 8-oxo-2-deoxyguanosine formation and inter-individual variability. Mutagenesis 16:467-474.

Iyer VN, Szybalski W. 1964. Mitomycins and porphyromycin: chemical mechanism of activation and crosslinking of DNA. Science 145:55-58.

Izzotti A, Bagnasco M, Camoirano A, Orlando M, De Flora S. 1998. DNA fragmentation, DNA-protein crosslinks, postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine. Mutat Res 400:233-244.

Joenje H, Arwert F, Eriksson AW, de Koning H, Oostra AB. 1981. Oxygen-dependence of chromosomal aberrations in Fanconi's anaemia. Nature 290:142-143.

Joenje H, Oostra AB. 1986. Clastogenicity of cyclophosphamide in Fanconi's anemia lymphocytes without exogenous metabolic activation. Cancer Genet Cytogenet 22:339-345.

Kontou M, Adelfalk C, Ramirez MH, Ruppitsch W, Hirsch-Kauffmann M, Schweiger M. 2002. 0verexpressed thioredoxin compensates Fanconi anemia related chromosomal instability. Oncogene 21:2406-2412.

Korkina LG, Deeva IB, laccarino M, De Biase A, 0ral R, Warnau M, et al. 2000. Redox-dependent toxicity of diepoxybutane and mitomycin C in sea urchin embryogenesis. Carcinogenesis 21:213-220.

Kruyt FA, Dijkmans LM, Arwert F, Joenje H. 1997. Involvement of the Fanconi's anemia protein FAC in a pathway that signals to the cyclin B/cdc2 kinase. Cancer Res 57:2244-2251.

Kruyt FA, Dijkmans LM, van den Berg TK, Joenje H. 1996. Fanconi anemia genes act to suppress a cross-linker-inducible p53-independent apoptosis pathway in lymphoblastoid cells lines. Blood 87:938-948.

Kruyt FA, Hoshino T, Liu JM, Joseph P, Jaiswal AK, Youssoufian H. 1998. Abnormal microsomal detoxification implicated in Fanconi anemia group C by interaction of the FAC protein with NADPH cytochrome P450 reductase. Blood 92:3050-3056.

Kupfer GM, D'Andrea AD. 1996. The effect of the Fanconi anemia polypeptide, FAC, upon p53 induction and G2 checkpoint regulation. Blood 88:1019-1025.

Madle S. 1981. Evaluation of experimental parameters in an S9/human leukocyte SCE test with cyclophosphamide. Mutat Res 85:347-356.

Mattagajasingh SN, Misra HP. 1999. Analysis of EDTA-chelatable proteins from DNA-protein crosslinks induced by a carcinogenic chromium(VI) in cultured intact human cells. Mol Cell Biochem 199:149-162.

Moustacchi E, Diatloff-Zito C. 1985. DNA semi-conservative synthesis in normal and Fanconi anemia fibroblasts following treatment with 8-methoxypsoralen and near ultraviolet light or with X-rays. Hum Genet 70:236-242.

Nguyen-nhu NT, Knoops B. 2002. Alkyl hydroperoxide reductase 1 protects Saccharomyces cerevisiae against metal ion toxicity and glutathione depletion. Toxicol Lett 135:219-228.

Nordenson I. 1977. Effect of superoxide dismutase and catalase on spontaneously occuring chromosome breaks in patients with Fanconi's anemia. Hereditas 86:147-150.

O'Brien T, Xu J, Patierno SR. 2001. Effects of glutathione on chromium-induced DNA crosslinking and DNA polymerase arrest. Mol Cell Biochem 222:173-182.

Pagano G. 2002. Redox-modulated xenobiotic action and ROS formation: a mirror or a window? Hum Exp Toxicol 21:77-81. Pagano G, Degan P, De Biase A, laccarino M, Warnau M. 2001. Diepoxybutane and mitomycin C toxicity is associated with the induction of oxidative DNA damage in sea urchin embryos. Hum Exp Toxicol 20:651-655.

Pagano G, Korkina LG. 2000. Prospects for nutritional interventions in the clinical management of Fanconi anemia. Cancer Causes Control 11:881-889.

Pagano G, Korkina LG, Brunk UT, Chessa L, Degan P, Del Principe D, et al. 1998. Congenital disorders sharing oxidative stress and cancer proneness as phenotypic hallmarks: prospects for joint research in pharmacology. Med Hypotheses 51:253-266.

Pagano G, Youssoufian H. 2003. Fanconi anaemia proteins: major roles in cell protection against oxidative damage. Bioessays 25:589-595.

Pearl-Yale M, Halperin D, Halevy A, Kalir H, Bielorai B, Fabian I. 2003. An oxidative mechanism of interferon induced priming of the Fas pathway in Fanconi anemia cells. Biochem Pharmacol 65:833-842.

Penketh PG, Hodnick WF, Belcourt MF, Shyam K, Sherman DH, Sartorelli AC. 2001. Inhibition of DNA crosslinking by mitomycin C by peroxidase-mediated oxidation of mitomycin C hydroquinone. J Biol Chem 276:34445-34452.

Poll EH, Arwert F, Joenje H, Eriksson AW. 1982. Cytogenetic toxicity of antitumor platinum compounds in Fanconi's anemia. Hum Genet 61:228-230. Poot M, Gross O, Epe B, Pflaum M, Hoehn H. 1996. Cell cycle defect in connection with oxygen and iron sensitivity in Fanconi anemia lymphoblastoid cells. Exp Cell Res 222: 262-268.

Pritsos CA, Sartorelli AC. 1986. Generation of reactive oxygen radicals through bioactivation of mitomycin antibiotics. Cancer Res 46:3528-3532.

Punnonen K, Jansen CT, Puntala A, Ahotupa M. 1991. Effects of in vitro UVA irradiation and PUVA treatment on membrane fatty acids and activities of antioxidant enzymes in human keratinocytes. J Invest Dermatol 96:255-259.

Quievryn G, Goulart M, Messer J, Zhitkovich A. 2001. Reduction of Cr (VI) by cysteine: significance in human lymphocytes and formation of DNA damage in reactions with variable reduction rates. Mol Cell Biochem 222:107-118.

Raj AS, Heddle JA. 1980. The effect of superoxide dismutase, catalase and L-cysteine on spontaneous and mitomycin C induced chromosomal breakage in Fanconi's anemia and normal fibroblasts as measured by the micronucleus method. Mutat Res 78:59-66.

Reinheckel T, Bohne M, Halangk W, Augustin W, Gollnick H. 1999. Evaluation of UVA-mediated oxidative damage to proteins and lipids in extracorporeal photoimmunotherapy. Photochem Photobiol 69:566-570.

Ruppitsch W, Meisslitzer C, Hirsch-Kauffmann M, Schweiger M. 1998. 0verexpression of thioredoxin in Fanconi anemia fibroblasts prevents the cytotoxic and ONA damaging effect of mitomycin C and diepoxybutane. FEBS Lett 422:99-102.

Rutherford TR, Clarke AA, Hewer A, Jenner DH, Phillips DH, Gordon-Smith EC, et al. 1999. DNA adduct formation, oxidative damage and apoptosis in Fanconi anemia cells [Abstract]. In: Proceedings of the 11th Annual International Fanconi Anemia Scientific Symposium, 1-2 December 1999, New Orleans, LA. Eugene, OR:FARF, Abstract 68.

Sawamura AO, Aoyama T, Tamakoshi K, Mizuno K, Suganuma N, Kikkawa F, et al. 1996. Transfection of human cytochrome P-450 reductase cDNA and its effect on the sensitivity to toxins. 0ncology 53:406-411.

Schaaf GJ, Maas RF, de Groene EM, Fink-Gremmels J. 2002. Management of oxidative stress by heme oxygenase-1 in cisplatin-induced toxicity in renal tubular cells. Free Radic Res 36:835-843.

Schulz JC, Shahidi NT. 1993. Tumor necrosis factor-[alpha] overproduction in Fanconi's anemia. Am J Hematol 42:196-201.

Seaton MJ, Follansbee MH, Bond JA. 1995. Oxidation of 1,2-epoxy-3-butene to 1,2:3,4-diepoxybutane by cDNA-expressed human cytochromes P450 2E1 and 3A4 and human, mouse and rat liver microsomes. Carcinogenesis 16:2287-2293.

Shi X, Dong Z, Huang C, Ma W, Liu K, Ye J, et al. 1999. The role of hydroxyl radical as a messenger in the activation of nuclear transcription factor NF-kappaB. Mol Cell Biochem 194:63-70.

Singh J, Bridgewater LC, Patierno SR. 1998. Differential sensitivity of chromium-mediated DNA interstrand crosslinks and DNA-protein crosslinks to disruption by alkali and EDTA. Toxicol Sci 45:72-76.

Spano M, Cordelli E, Leter G, Pacchierotti F. 1998. Diepoxybutane cytotoxicity on mouse germ cells is enhanced by in vivo glutathione depletion: a flow cytometric approach. Mutat Res 397:37-43.

Stohs SJ, Bagchi D. 1995. Oxidative mechanisms in the toxicity of metal ions. Free Radic Biol Med 18:321-336.

Takeuchi T, Morimoto K. 1993. Increased formation of 8-hydroxy-deoxyguanosine, an oxidative DNA damage, in lymphoblasts from Fanconi's anemia patients due to possible catalase deficiency. Carcinogenesis 14:1115-1120.

Tamary H, Bar-Yam R, Zemach M, Dgany O, Shalmon L, Yaniv I. 2002. The molecular biology of Fanconi anemia. Isr Med Assoc J 4:819-823.

Taylor WR, Stark GR. 2001. Regulation of the G2/M transition by p53, 0ncogene 20:1803-1815.

Travacio M, Polo JM, Llesuy S. 2000. Chromium (VI) induces oxidative stress in the mouse brain. Toxicology 150:137-146.

Tsou TC, Chen CL, Liu TY, Yang JL. 1996. Induction of 8-hydroxy-deoxyguanosine in DNA by chromium(III) plus hydrogen peroxide and its prevention by scavengers. Carcinogenesis 17:103-108.

Vilcheck SK, 0'Brien T J, Pritchard DE, Ha L, Ceryak S, Fornsaglio JL, et al. 2002. Fanconi anemia complementation group A cells are hypersensitive to chromium(VI)-induced toxicity. Environ Health Perspect 110(suppl 5):773-777.

Vlachodimitropoulos D, Norppa H, Autio K, Catalan J, Hirvonen A, Tasa B, et al. 1997. GSTT1-dependent induction of centromere-negative and -positive micronuclei by 1,2,3,4-diepoxybutane in cultured human lymphocytes. Mutagenesis 12:397-403.

Waisfisz Q, Miyazato A, de Winter J, Liu JM, Joenje H. 2002. Analysis of baseline and cisplatin-inducible gene expression in Fanconi anemia cells using oligonucleotide-based microarrays. BMC Blood Disord 2:5. Available: http:// www.biomedcentral.com/1471-2326/2/5/[accessed 14 August 2003].

Will O, Schindler D, Boiteux S, Epe B. 1998. Fanconi's anaemia cells have normal steady-state levels and repair of oxidative DNA base modifications sensitive to Fpg protein. Mutat Res 409:65-72.

Giovanni Pagano, (1) Paola Manini, (2) and Debasis Bagchi (3)

(1) Italian National Cancer Institute, Pediatric Oncology Research Center, Mercogliano, Italy; (2) Department of Organic Chemistry and Biochemistry, Federico II Naples University, Naples, Italy; (3) Department of Pharmacy Sciences, Creighton University School of Pharmacy and Health Professions, Omaha, Nebraska, USA

Address correspondence to G. Pagano, Istituto Nazionale Tumori, Centro Ricerche in Oncologia Pediatrica, via Ammiraglio Bianco, I-83013 Mercogliano (AV), Italy. Telephone: 39-335-6910060. Fax: 39-081-3031141. E-mail: gbpagano@ tin.it

We thank F. Panzeri for skillful assistance.

G.P. participated in this study through the European Research on Oxidative Stress (EUROS) Project; the study was supported by the European Commission DGXII (contract BMH4-CT98-3107) and by the Italian Association for Fanconi Anemia Research.

The authors declare they have no conflict of interest.

Received 22 January 2003; accepted 12 June 2003.

COPYRIGHT 2003 National Institute of Environmental Health Sciences
COPYRIGHT 2004 Gale Group