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Although the estrogenic properties of numerous chloroorganic pesticides have been widely recognized, population studies do not give clear results indicating the link between the exposure to these compounds and breast cancer development. Because of the weak affinity of these pesticides to estrogen receptors, they probably act by affecting the expression of CYP genes encoding cytochromes P450 engaged in the metabolism of environmental as well as natural estrogens. To examine the possible correlation between environmental estrogen levels in adipose tissue and breast cancer stage, grade, receptor status and onset of the disease, adipose tissue was isolated from 54 breast cancer patients and 23 healthy individuals. Clinical characteristics were obtained from the medical records, while the information concerning exposure to environmental estrogens where obtained from questionnaires. The environmental estrogens were identified and quantified by GC-chromatography. The data was analyzed with the use of Student t-test and Spearman correlation. The levels of most environmental estrogens did not differ between the patients and the controls, except the β -HCH (β -hexachlorocyclohexane) level, which was higher in the patients than in the healthy individuals. Significantly higher levels of DDE (1,1-bis(4-chlorophenyl)-2,2-dichloroethene) and DDT (1,1,1-trichloro-2,2-bis(4-chlorophenol)ethane) (P < 0.05) were observed in the patients with late onset of the disease which was probably due to the time of exposure. Moreover, in the patients exposed to environmental estrogens, significantly higher concentrations of DDD (1,1-bis(4-chlorophenyl)-2,2-dichloroethane) were found (P < 0.05). We also evidenced that estrogen-independent cancer was more frequent in the patients exposed to numerous risk factors in which higher levels of HCB (hexachlorobenzene), γ -HCH (γ -hexachlorocyclohexane), DDD and DDT in adipose tissue were detected. Breast cancer development is probably related to the accumulation of DDT and its derivatives, but the effect appears only in older patients. We postulate that environmental estrogens acting together with other risk factors might influence the progress and exacerbate the prognosis of breast cancer. [ABSTRACT FROM AUTHOR]

Objective. Transforming growth factor β (TGF-β) is a potent inhibitor of 17α-hydroxylase/17,20 lyase activity and CYP17 gene expression. We investigated the mechanism how CYP17 is inhibited by TGF-β in adrenocortical cells. Methods. H295R cells were culture and incubated with TGF-β, transcription inhibitor (DRB), activin receptor-like kinase 5 ALK5 (TβRII) inhibitor (SB431542), mitogen activated kinases inhibitors (PD98059 and SB203580), subsequently using reverse transcription and quantitative PCR (RT-qPCR) we determined CYP17 expression. Results. TGF-β significantly decreased the level of cytochrome P450c17 mRNA and this inhibitory effect of TGF-β on CYP17 expression required activin receptor-like kinase 5 (ALK5) and on-going transcription. Mitogen activated kinases MEK1 and p38 MAPK are not involved it the inhibitory effect of TGF-β on CYP17 expression. Conclusion. We concluded that the TGF-β-dependent decrease of 17α-hydroxylase/17,20 lyase activity in the H295R cells is caused by inhibition of CYP17 transcription and is mediated by the ALK5 receptor. [ABSTRACT FROM AUTHOR]

The orphan nuclear receptor, steroidogenic factor 1 (SF-1), plays a major role in adrenal and gonadal development, as well as in sexual differentiation. It has been demonstrated that the expression of a number of genes regulated by SF-1 is inhibited by the transforming growth factor β (TGF-β). To date, however, the influence of TGF-β on the expression of SF-1 gene has not been reported. A Northern blot analysis with the use of a radiolabeled cDNA probe, and immunodetection with antibodies directed against SF-1, demonstrated that the Sf-1 transcript and the SF-1 protein levels were lowered by TGF-β in Y-1 adrenocortical cells, both in untreated and adenylyl cyclase activator, forskolin-treated cells. An examination of the Sf-1 transcript stability in the presence of actinomycin D revealed no influence of TGF-β on the rate of Sf-1 mRNA decay. Inhibition of Sf-1 expression by TGF-β was abolished by cycloheximide, suggesting that the growth factor inhibitory effect requires ongoing protein synthesis. We conclude that in Y-1 cells TGF-β inhibits the expression of SF-1 gene at a transcriptional level, and we postulate that the inhibitory effect of TGF-β on steroid hormone synthesis in the adrenal cortex could be due to an attenuated transcription of Sf-1 . [ABSTRACT FROM AUTHOR]

The regulation of 11β-hydroxysteroid dehydrogenase type II (11βHSD2) expression at the level of specific mRNA and 11βHSD2 protein was investigated in primary culture of renal epithelial cells of the rat. It has been shown that treatment of the SE cells with adenylyl cyclase activator, forskolin, known to stimulate the protein kinase A (PKA) pathway, resulted in an increase in 11βHSD2 mRNA content in these cells. Semi-quantitative RT-PCR revealed that the effect of forskolin was attenuated by the addition of phorbol ester, tetradecanoyl phorbol acetate (TPA), an activator of the protein kinase C (PKC) pathway, whereas TPA on its own slightly reduced the basal level of 11βHSD2 expression judging from the content of specific mRNA. Measurements of [[SUP35]S]-methionine incorporation into immunoprecipitable 11βHSD2 revealed an increased synthesis of this protein in renal epithelial cells treated with forskolin. Phorbol ester TPA markedly reduced the effect of forskolin on the synthesis of 11βHSD2 and attenuated the basal level of synthesis of this protein. It is concluded that in renal epithelial cells in primary culture, stimulation of PKA pathway results in the induction of 11βHSD2 both at a specific mRNA and effect is markedly reduced by activation of PKC pathway. [ABSTRACT FROM AUTHOR]