Gynecological diseases such as endometriosis, adenomyosis and uterine fibroids, and gynecological cancers including endometrial cancer and ovarian cancer, affect a large proportion of women. These ...diseases are estrogen dependent, and their progression often depends on local estrogen formation. In peripheral tissues, estrogens can be formed from the inactive precursors dehydroepiandrosterone sulfate and estrone sulfate. Sulfatase and sulfotransferases have pivotal roles in these processes, where sulfatase hydrolyzes estrone sulfate to estrone, and dehydroepiandrosterone sulfate to dehydroepiandrosterone, and sulfotransferases catalyze the reverse reactions. Further activation of estrone to the most potent estrogen, estradiol, is catalyzed by 17-ketosteroid reductases, while estradiol can also be formed from dehydroepiandrosterone by the sequential actions of 3β-hydroxysteroid dehydrogenase-Δ(4)-isomerase, aromatase, and 17-ketosteroid reductase. This review introduces the sulfatase and sulfotransferase enzymes, in terms of their structures and reaction mechanisms, and the regulation and different transcripts of their genes, together with the importance of their currently known single nucleotide polymorphisms. Data on expression of sulfatase and sulfotransferases in gynecological diseases are also reviewed. There are often unchanged mRNA and protein levels in diseased tissue, with higher sulfatase activities in cancerous endometrium, ovarian cancer cell lines, and adenomyosis. This can be indicative of a disturbed balance between the sulfatase and sulfotransferases enzymes, defining the potential for sulfatase as a drug target for treatment of gynecological diseases. Finally, clinical trials with sulfatase inhibitors are discussed, where two inhibitors have already concluded phase II trials, although so far with no convincing clinical outcomes for patients with endometrial cancer and endometriosis.
Family 19 of the P450 super family is responsible for the conversion of C19 androgenic steroids to the corresponding estrogens, a reaction known as aromatization because it involves conversion of the ...Δ4‐3‐one A‐ring of the androgens to the corresponding phenolic A‐ring characteristic of estrogens. The gene encoding human aromatase has been cloned and characterized and shown to be unusual compared to genes encoding other P450 enzymes, because there are numerous untranslated first exons that occur in aromatase transcripts in a tissue‐specific fashion due to differential splicing as a consequence of the use of tissue‐specific promoters. Thus, expression in the ovary uses a proximal promoter that is regulated primarily by cAMP. On the other hand, expression in the placenta uses a distal promoter located at least 40 kb upstream of the start of transcription that is regulated by retinoids. Other promoters are used in brain and adipose tissue. In the latter case, class I cytokines such as IL‐6 and IL‐11, as well as TNF‐α, are important regulatory factors. A common 3‘‐splice junction located upstream of the start of translation is used in all of the splicing events involved in the use of these various promoters. Thus, the coding region of the transcripts, and hence the protein, are identical regardless of the tissue site of expression; what differs in a tissue‐specific fashion is the 5‘‐end of the transcripts. This pattern of expression has great significance both from a phylogenetic and ontogenetic standpoint, as well as for the physiology and pathophysiology of estrogen formation, as will be discussed in thie review.—Simpson, E. R., Michael, M. D., Agarwal, V. R., Hinshelwood, M. M., Bulun, S. E., Zhao, T. Expression of the CYP19 (aromatase) gene: an unusual case of alternative promoter usage. FASEB J. 11, 29‐36 (1997)
To assess the prognostic significance of intratumoral aromatase in endometrioid endometrial cancer, sections from 55 patients with endometrial cancer were evaluated for expression of aromatase using ...immunohistochemistry, and the correlation between aromatase expression and clinicopathologic parameters were analyzed.
Immunohistochemical staining for aromatase was positive for 32 (58%), 20 (36%), and 19 (34%) patients in cancer epithelial cells, stromal cells, and myometrial cells around the flank invasion, respectively. In situ hybridization also detected aromatase mRNA in all three types of cells. RT-PCR analysis revealed that aromatase mRNA was 2.5 +/- 1.0 amol/mug total RNA (mean +/- SE; n = 7) in tumor tissue. Western blot analysis detected the expected aromatase protein size of 58 kDa in cancer tissues more abundantly than in cancer-free endometrium (n = 3). The immunoreactivity in stromal cells correlated positively with advanced surgical stage and poor survival. Survival analysis revealed that the immunoreactivity of stromal cells was a significant prognostic factor, independent of histologic grade, muscular invasion, and lymph node metastasis, but dependent on surgical stage. By contrast, the immunoreactivity of aromatase both in cancer epithelial cells and myometrial cells did not correlate with prognosis.
To the best of our knowledge, this is the first evidence associating intratumoral aromatase expression in stromal cells and poor survival in endometrioid endometrial cancer. This positive linkage indicates that local expression of aromatase plays a role in tumor progression through the formation of in situ estrogens. In situ expression of aromatase may offer a potential target for management of endometrial cancers.
Aromatase, cytochrome P450 19, is a key enzyme in the biosynthesis of estrogens by the human placenta. It is also the major placental enzyme that metabolizes the opiates l-acetylmethadol (LAAM), ...methadone, and buprenorphine (BUP). Methadone and BUP are used in treatment of the opiate addict and are competitive inhibitors of testosterone conversion to estradiol (E2) and 16α-hydroxytestosterone (16-OHT) to estriol (E3) by aromatase. The aim of this investigation is to determine the effect of 20 opiates, which can be administered to pregnant patients for therapeutic indications or abused, on E2 and E3 formation by placental aromatase. Data obtained indicated that the opiates increased, inhibited, or had no effect on aromatase activity. Their effect on E3 formation was more pronounced than that on E2 due to the lower affinity of 16-OHT than testosterone to aromatase. The Ki values for the opiates that inhibited E3 formation were sufentanil, 7±1μM; LAAM, 13±8μM; fentanyl, 25±5μM; oxycodone, 92±22μM; codeine, 218±69μM; (+)-pentazocine, 225±73μM. The agonists morphine, heroin, hydromorphone, oxymorphone, hydrocodone, propoxyphene, meperidine, levorphanol, dextrorphan, and (−)-pentazocine and the antagonists naloxone and naltrexone caused an increase in E3 formation by 124–160% of control but had no effect on E2 formation. Moreover, oxycodone and codeine did not inhibit E2 formation and the IC50 values for fentanyl, sufentanil, and (+)-pentazocine were >1000μM. It is unlikely that the acute administration of the opiates that inhibit estrogen formation would affect maternal and/or neonatal outcome. However, the effects of abusing any of them during the entire pregnancy are unclear at this time.
Methadone and buprenorphine (BUP) are used for treatment of the pregnant opiate addict. CYP19/aromatase is the major placental enzyme responsible for the metabolism of methadone to ...2-ethylidine-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and BUP to norbuprenorphine (norBUP). The aim of this investigation was to determine the effects of methadone and BUP on the activity of placental microsomal aromatase in the conversion of its endogenous substrates testosterone to 17β-estradiol (E
2) and 16α-hydroxytestosterone (16-OHT) to estriol (E
3). The conversion of testosterone and 16-OHT by human placental microsomes exhibited saturation kinetics, and the apparent
K
m values were 0.2
±
1 and 6
±
3
μM, respectively.
V
max values for E
2 and E
3 formation were 70
±
16 and 28
±
10
pmol/mg protein
min, respectively. Also, data obtained revealed that methadone and BUP are competitive inhibitors of testosterone conversion to E
2 and 16-OHT to E
3. The
K
i for methadone inhibition of E
2 and E
3 formation were 393
±
144 and 53
±
28
μM, respectively, and for BUP the
K
i was 36
±
9 and 6
±
1
μM. The higher potency of the two opiates and their metabolites in inhibiting E
3 formation is in agreement with the lower affinity of 16-OHT than testosterone to aromatase. Moreover, the metabolites EDDP and norBUP were weaker inhibitors of aromatase than their parent compounds. The determined inhibition constants of methadone and BUP for E
3 formation by a cDNA-expressed CYP19 preparation were similar to those for placental microsomes. Therefore, data reported here suggest that methadone, BUP, and their metabolites are inhibitors of androgen aromatization in the placental biosynthesis of estrogens.
The oral administration of indole-3-carbinol (IC), present in cabbage and other members of the Cruciferae family, to female rats almost doubled their ability to convert estradiol to catechol ...estrogens in the liver. This was determined by the release of 3H from C-2 of the estrogen and also by isolation of the 14C-labeled catechol derivative after incubation with hepatic microsomal fractions. The yield of 4-hydroxyestradiol was also elevated and these effects were similar to those produced by 3-methylcholanthrene (MC), a well-characterized cytochrome P450 inducer. Further evidence for the involvement of a mixed-function oxidase was provided by a 70% to 80% decrease in the yield of 3H2O and water-soluble radioactivity by SKF-525A (0.1 mM) when added to the microsomal fractions isolated from the livers of control or IC-treated rats. In addition, NADPH could not be replaced by NADH in these experiments. Pretreatment with ethionine prevented the increase in estradiol metabolism brought about by oral administration of IC. Both IC and MC inhibited catechol estrogen formation when added directly to the liver microsomal system, confirming earlier findings that in vivo inducers can act as in vitro inhibitors. However, IC was less inhibitory than MC, supporting the theory that IC is converted to a more active product in the stomach. Thus, IC may be conferring protection against estrogen-dependent neoplasia by increasing the hepatic oxidation of estradiol, thereby lowering the amount of available active estrogen.
Adipose tissue is the major site of estrogen formation in postmenopausal women. We have previously reported (Simpson, E.R., Ackerman, G.E., Smith, M.E. and Mendelson, C.R. (1981) Proc. Natl. Acad. ...Sci. (U.S.A.) 78, 5690-5694; Mendelson, C.R., Cleland, W.H., Smith, M.E. and Simpson, E.R. (1982) Endocrinology 111, 1077-1085) that aromatase activity of human adipose stromal cells in culture is stimulated by glucocorticoids and by dibutyryl cyclic AMP (Bt2-cAMP). In order to establish which physiological factors might stimulate aromatase activity of these cells by activation of adenylate cyclase, we have investigated the roles of adrenocorticotropin (ACTH) and isoproterenol to increase cyclic AMP levels and stimulate the aromatization of androstenedione. In the presence of methylisobutylxanthine (MIX), ACTH stimulated cyclic AMP formation and aromatase activity in a time- and concentration-dependent manner. The concentration of ACTH required for half-maximal stimulation was approximately 10(-8) M. Isoproterenol, in the presence of MIX, stimulated cyclic AMP formation in a time- and concentration-dependent fashion, and also stimulated aromatase activity. These effects of isoproterenol appeared to be mediated by binding of the agonist to a population of beta-adrenergic receptors. On the basis of these and our previous studies, we suggest that ACTH may play an important role in stimulating estrogen formation by human adipose tissue, both directly, and by stimulating the adrenal cortex to produce both substrate, androstenedione, and inducing agent, namely cortisol.
Induction effect of phenobarbital (80mg/kg, daily for 4d), 3-methylcholanthrene (40mg/kg, daily for 4d), and isosafrole (150mg/kg, daily for 4d), on 2-and 4-hydroxylations of estradiol 17-sulfate by ...rat liver microsomes with an NADPH-generating system was investigated. On catechol formation from estradiol 17-sulfate, only phenobarbital caused some increase of the 2-hydroxylase activity in both sexes. While 4-hydroxylase activity was caused effectively by phenobarbital and isosafrole in both sexes, especially, the induction by the former in male rats was over six-fold increase to the control.
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