Synchronous bilateral primary germ cell tumors in patient receiving estrogen therapy

Methyltertiary-Butyl Ether: Studies for Potential Human Health Hazards

When methyl tertiary-butyl ether (MTBE) in gasoline was first introduced to reduce vehicle exhaust emissions and comply with the Clean Air Act, in the United States, a pattern of complaints emerged characterised by seven "key symptoms." Later, carefully controlled volunteer studies did not confirm the existence of the specific key symptoms, although one study of self-reported sensitive (SRS) people did suggest that a threshold at about 11-15% MTBE in gasoline may exist for SRSs in total symptom scores. Neurobehavioral and psychophysiological studies on volunteers, including SRSs, found no adverse responses associated with MTBE at likely exposure levels. MTBE is well and rapidly absorbed following oral and inhalation exposures. Cmax values for MTBE are achieved almost immediately after oral dosing and within 2 h of continuous inhalation. It is rapidly eliminated, either by exhalation as unchanged MTBE or by urinary excretion of its less volatile metabolites. Metabolism is more rapid humans than in rats, for both MTBE and tert-butyl alcohol (TBA), its more persistent primary metabolite. The other primary metabolite, formaldehyde, is detoxified at a rate very much greater than its formation from MTBE. MTBE has no specific effects on reproduction or development, or on genetic material. Neurological effects were observed only at very high concentrations. In carcinogenicity studies of MTBE, TBA, and methanol (included as an endogenous precursor of formaldehyde, without the presence of TBA), some increases in tumor incidence have been observed, but consistency of outcome was lacking and even some degree of replication was observed in only three cases, none of which had human relevance: alpha(2u)-globulin nephropathy-related renal tubule cell adenoma in male rats; Leydig-cell adenoma in male rats, but not in mice, which provide the better model of the human disease; and B-cell-derived lymphoma/leukemia of doubtful pathogenesis that arose mainly in lungs of orally dosed female rats. In addition, hepatocellular adenomas were significantly higher in female CD-1 mice and thyroid follicular-cell adenomas were increased in female B6C3F1 mice treated with TBA, but these results lack any independent confirmation, which would have been possible from a number of other studies.

Estrogen-induced generation of reactive oxygen and nitrogen species, gene damage, and estrogen-dependent cancers

In addition to the direct effect of estrogen on mitochondria and the redox cycling of catechol estrogen, estrogen-induced proinflammatory cytokines, such as interleukin-1 beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha), also generate reactive oxygen and nitrogen species (RO/NS). Different cellular signaling pathways may operate in response to varying levels of estrogen-induced RO/NS, leading to genotoxic damage, cell apoptosis, or cell growth. At high levels of RO/NS, cells receiving genotoxic insults, if not repaired, may engage the apoptotic pathways. There is increasing evidence supporting that estrogen-induced alterations in the genome of cells is produced by oxidative attack. Furthermore, ROS generated by estrogen exposure and/or active metabolites of estrogen in combination with receptor-mediated proliferation of genetically damaged cells may be involved in tumor development. This view is supported by the findings of DNA modifications produced in vitro or in vivo by natural and synthetic estrogens in the target organs of cancer both in experimental models and in humans. Interaction of estrogen-induced oxidants and estrogen metabolites with DNA was shown to generate mutations in genes. Cotreatment with an inhibitor of IL-1beta and TNF-alpha synthesis, pentoxifylline, decreased stilbene estrogen-induced levels of myeloperoxidase (MPO), 8-hydroxydeoxyguanosine formation, and gene mutations, and prevented stilbene estrogen-induced lesions. Stable MCF-7 clones overexpressing IL-1beta resulted in a high level of IL-1beta peptide secretion undergoing cell apoptosis, and an elevated level of p53 protein in response to high oxidative stress when compared to nontransfected cells, whereas MCF-7 clones overexpressing IL-1beta that resulted in a moderate level of IL-1beta secretion stimulated the clonal expansion of MCF-7 and TM3 cells. Estrogen-induced MCF-7 cell growth and cyclin D1 expression were suppressed by antioxidants and mitochondrial blockers. These studies support that in addition to ovarian estrogen-mediated ER signaling, mitogenic signals may also come from estrogen-induced RO/NS. Further validation of this concept that the concentration of the RO/NS within the cellular microenvironment determines its stimulatory or inhibitory growth signals as well as its genotoxic effects regulating the growth of estrogen-dependent tumors may result in novel preventive strategies.

Prostate carcinoma presenting as multiple pulmonary nodules in an asymptomatic patient with a history of testicular nonseminomatous germ cell tumor

Prostate carcinoma presenting initially as multiple pulmonary nodules in an asymptomatic patient without previous prostate carcinoma is unusual. Whether the incidence of prostate carcinoma is significantly increased in patients treated previously for germ cell tumors is unclear. We report such a patient, who responded to combination androgen blockade therapy.