Heterogeneous risk attitudes and waves of infection.

Many countries have experienced multiple waves of infection during the COVID-19 pandemic. We propose a novel but parsimonious extension of the SIR model, a CSIR model, that can endogenously generate waves. In the model, cautious individuals take appropriate prevention measures against the virus and are not exposed to infection risk. Incautious individuals do not take any measures and are susceptible to the risk of infection. Depending on the size of incautious and susceptible population, some cautious people lower their guard and become incautious-thus susceptible to the virus. When the virus spreads sufficiently, the population reaches "temporary" herd immunity and infection subsides thereafter. Yet, the inflow from the cautious to the susceptible eventually expands the susceptible population and leads to the next wave. We also show that the CSIR model is isomorphic to the SIR model with time-varying parameters.

Population-Level Immunity for Transient Suppression of COVID-19 Waves in Japan from April 2021 to September 2022.

Multiple COVID-19 waves have been observed worldwide, with varying numbers of positive cases. Population-level immunity can partly explain a transient suppression of epidemic waves, including immunity acquired after vaccination strategies. In this study, we aimed to estimate population-level immunity in 47 Japanese prefectures during the three waves from April 2021 to September 2022. For each wave, characterized by the predominant variants, namely, Delta, Omicron, and BA.5, the estimated rates of population-level immunity in the 10-64-years age group, wherein the most positive cases were observed, were 20%, 35%, and 45%, respectively. The number of infected cases in the BA.5 wave was inversely associated with the vaccination rates for the second and third injections. We employed machine learning to replicate positive cases in three Japanese prefectures to validate the reliability of our model for population-level immunity. Using interpolation based on machine learning, we estimated the impact of behavioral factors and vaccination on the fifth wave of new positive cases that occurred during the Tokyo 2020 Olympic Games. Our computational results highlighted the critical role of population-level immunity, such as vaccination, in infection suppression. These findings underscore the importance of estimating and monitoring population-level immunity to predict the number of infected cases in future waves. Such estimations that combine numerical derivation and machine learning are of utmost significance for effective management of medical resources, including the vaccination strategy.

Correction to: COVID­19 and output in Japan.

[This corrects the article DOI: 10.1007/s42973-021-00098-4.].

COVID-19 and output in Japan.

We build a tractable SIR-macro-model with time-varying parameters and use it to explore various policy questions such as when to lift the state of emergency (SOE). An earlier departure from the SOE results in smaller output loss and more deaths in the short run. However, if the SOE is lifted too early, the number of new cases will surge and another SOE may need to be issued in the future, possibly resulting in both larger output loss and more deaths. That is, the tradeoff between output and infection that exists in the short run does not necessarily exist in the long run. Our model-based analysis-updated weekly since January 2021, frequently reported by media, and presented to policymakers on many occasions-has played a unique role in the policy response to the COVID-19 crisis in Japan.

[Steroid sulfatase inhibitor].

More than 60 percents of breast cancers occur in post menopausal women and most of their initial stages are hormone dependent. For the treatment of estrogen dependent breast tumors, mainly two treatment tools are available, one is selective estrogen receptor modulator (SERM), and the other is aromatase inhibitor (AI). Although these drugs are clinically valuable, the existence of resistant tumors againt these two treatments is one of the most serious matters. The latest studies clarify that to inhibit the local formation of estrogen is more important than to decrease the estrogen dose in plasma. Steroid sulfatase (STS) is mainly expressed in local breast carcinoma tissues and is one of the most promising targets to inhibit the local formation of estrogens.

Expression level of enzymes related to in situ estrogen synthesis and clinicopathological parameters in breast cancer patients.

In order to evaluate the importance of estrogen production in tumor and surrounding tissues, we measured mRNA expression levels of 5 enzymes participating to estrogen synthesis in situ and 4 breast cancer-related proteins in 27 pairs of tumor and non-malignant tissues. Steroid sulfatase (STS) mRNA was more frequently detected in tumor tissues rather than in their non-malignant counterparts. Estrogen sulfotransferase (EST) was constantly expressed with high level not only in tumor tissues but also in their surrounding non-malignant counterparts. In contrast, mRNA expression levels of aromatase, and 17beta-hydroxysteroid dehydrogenase type I and II were relatively low and detected only in small proportion of the patients. We also measured the mRNA expression levels of the same nine genes in tumor tissues of 197 breast cancer patients, and analyzed relationship between the mRNA expression level and the clinicopathological parameters. The mRNA expression levels of STS, aromatase and erbB2 in tumor tissues increased as breast cancer progressed. The tumoral mRNA expression levels of STS, estrogen receptor beta, and erbB2 in patients with recurrence were higher than those in patients without recurrence. Upregulation of STS expression plays an important role in tumor progression of human breast cancer and is considered to be responsible for estrogen production in tumor and surrounding tissues.

A novel steroidal selective steroid sulfatase inhibitor KW-2581 inhibits sulfated-estrogen dependent growth of breast cancer cells in vitro and in animal models.

We screened a series of 17beta-(N-alkylcarbamoyl)-estra-1,3,5(10)trine-3-O-sulfamate derivatives, and describe here a potent and selective steroid sulfatase (STS) inhibitor with antitumor effects in breast cancer models in vitro and in vivo. In biochemical assays using crude enzymes isolated from recombinant Chinese hamster ovary cells expressing human arylsulfatses (ARSs), one of the best compounds, KW-2581, inhibited STS activity with an IC(50) of 4.0 nM, while > 1000-fold higher concentrations were required to inhibit the other ARSs. The failure to stimulate the growth of MCF-7 human breast cancer cells as well as in uteri in ovariectomized rats indicated the lack of estrogenicity of this compound. In MCF-7 cells transfected with the STS gene, termed MCS-2 cells, KW-2581 inhibited the growth of cells stimulated by estrone sulfate (E1S) but also 5-androstene-3beta, 17beta-diol 3-sulfate (ADIOLS) and dehydroepiandrostenedione 3-sulfate. We found that oral administration of KW-2581 inhibited both E1S- and ADIOLS-stimulated growth of MCS-2 cells in a mouse hollow fiber model. In a nitrosomethylurea-induced rat mammary tumor model, KW-2581 induced regression of E1S-stimulated tumor growth as effectively as tamoxifen or another STS inhibitor, 667 Coumate. Dose-response studies in the same rat model demonstrated that more than 90% inhibition of STS activity in tumors was necessary to induce tumor shrinkage. STS activity in tumors has well correlated with that in leukocytes, suggesting that STS activity in leukocytes could be used as an easily detectable pharmacodynamic marker. These findings demonstrate that KW-2581 is a candidate for development as a therapeutic agent for the treatment of hormone receptors-positive breast cancer.

Inhibition of steroid sulfatase activity and cell proliferation in ZR-75-1 and BT-474 human breast cancer cells by KW-2581 in vitro and in vivo.

In the present study, we found that two hormone receptor-positive human breast cancer cell lines, ZR-75-1 and BT-474, naturally expressed steroid sulfatase (STS) protein and had catalytic activity to produce estrone from estrone sulfate (E1S) with a comparable level to those in human breast cancer tissues. E1S at physiological concentrations stimulated the growth of those cells. A novel steroidal STS inhibitor, KW-2581 inhibited the STS activity of ZR-75-1 cells with an IC(50) of 13 nM, a potency equal to or higher than that of the non-steroidal STS inhibitor, 667 COUMATE. The inhibitory effect of KW-2581 was enhanced by pre-incubation with STS enzyme, suggests being irreversible inhibition. KW-2581 inhibited the E1S-stimulated growth of ZR-75-1 cells with an IC(50) of 0.18 nM, but failed to inhibit the growth stimulated by 17beta-estradiol. Expression of E1S-induced progesterone receptors in ZR-75-1 cells was reduced by treatment of KW-2581 at concentrations as low as 0.1 nM. Oral administration of KW-2581 for 4 weeks caused tumor shrinkage in a mouse xenograft model. Tumor STS activity had been completely (>95%) eliminated by 24 hours after the last administration. These findings suggest that KW-2581 has considerable potential for therapeutic development as a novel anti-hormonal drug for treatment of breast cancer.

New development in intracrinology of breast carcinoma: therapeutic horizons after aromatase inhibitors.

Aromatase inhibitors have become the gold standard of endocrine therapy in postmenopausal patients with estrogen receptor-positive or estrogen-dependent breast carcinoma, replacing tamoxifen. However, it is true that there are some potential problems to be overcome or improved on regarding aromatase inhibitor treatment of breast cancer. This especially includes the presence of the estrogen receptor-positive patients who do not necessarily respond to aromatase inhibitors, may require other modes of endocrine therapy and develop resistance to aromatase inhibitor in their clinical course, and who may also need alternative modes of suppressing intratumoral estrogen signals or other intracellular signal pathways related to tumor progression or development. Intratumoral estrogen production from precursors present in circulation in an 'intracrine' manner is considered to play very important roles in the development and progression of estrogen receptor-positive breast cancer. The great majority of estrone in circulation is present as a sulfated form or estrone sulfate, and steroid sulfatase hydrolyzes circulating estrone sulfate to estrone in various human tissues in situ, which confers potent estrogenic actions. Estrone is subsequently reduced to 17ß-estradiol by 17ß-hydroxysteroid dehydrogenase type 1. Therefore, these two enzymes also play very important roles in intracrinology of estrogen in breast cancer in addition to intratumoral aromatase, and the potential inhibition of these two enzymes could lead to the development of a new mode of endocrine therapy based on intracrinology, which may overcome some of the problems above in aromatase inhibitor therapy. In this review, the potential advantages and pitfalls or problems associated with the inhibition of these two intratumoral enzymes in breast cancer patients will be discussed.

New development in intracrinology of breast carcinoma.

Intratumoral metabolism and synthesis of estrogens as a result of the interactions of various enzymes are considered to play very important roles in the pathogenesis and development of hormone dependent breast carcinoma. Among these enzymes, intratumoral aromatase plays as important role converting serum androgens to estrogens in situ, and serves as a source of estrogen, especially in postmenopausal patients with breast carcinoma. However, other enzymes such as the 17beta-hydroxysteroid dehydrogenase (17beta-HSD) isozymes, estrogen sulfatase (STS) and estrogen sulfotransferase, also play pivotal roles in intratumoral estrogen production. The 17beta-hydroxysteroid dehydrogenase (17beta-HSD) isozymes catalyze the interconversion of estradiol (E2) and estrone (E1), and thereby serve to modulate the tissue levels of bioactive E2 in human breast carcinoma. 17Beta-HSD type 1 catalyzes primarily the reduction of estrone (E1) to estradiol (E2), whereas 17beta-HSD type 2 catalyzes primarily the oxidation of E2 to E1. In human breast disease, 17beta-HSD type 1 is expressed in proliferative disease without atypia, atypical ductal hyperplasia, ductal carcinoma in situ and invasive ductal carcinoma. 17Beta-HSD type 2 has not been detected in any of these breast lesions. In addition, 17beta-HSD type 1 coexpression is significantly correlated with estrogen receptor status in invasive ductal carcinoma cases. These results indicate that breast carcinoma can effectively convert E1, produced as a result of in situ aromatization, to E2, a biologically potent estrogen, which exerts estrogenic actions on tumor cells through estrogen receptor, especially the alpha subtype in carcinoma cells. Therefore, inhibiting intratumoral 17beta-HSD type 1 is also considered to contribute to inhibition of cell proliferation by decreasing intratumoral estradiol. Estrogen sulfotransferase (EST; SULT 1E1 or STE gene) sulfonates estrogens to inactive estrogen sulfates, while steroid sulfatase (STS) hydrolyzes estrone sulfate (E1-S) to estrone. EST immunoreactivity was recently demonstrated to be significantly associated with a decreased risk of recurrence or improved prognosis by both uni- and multivariate analyses. STS immunoreactivity was significantly associated with an increased risk of recurrence by univariate analysis. These findings also suggest that EST and STS plays important roles in regulation of in situ estrogen production, and EST especially is a potent prognostic factor in human breast carcinoma. Therefore, the inhibition of intratumoral STS might also serve as an endocrine therapy in postmenopausal patients. It is also important to note that the status of intratumoral aromatase, 17beta-HSD type 1, EST and STS in human breast cancer tissues is variable and not necessarily correlated with each other, which suggests different potential sources of intratumoral estrogens among individual patients with breast cancer. These findings indicate that there are patients who could benefit more from inhibition of these intratumoral enzymes rather than aromatase inhibition as an endocrine therapy. Therefore, it will become very important to examine the intratumoral levels of 17beta-HSD type 1 and STS in the resected specimens of human breast carcinoma as potential targets of novel endocrine therapy in the near future.

Estrogen inhibits cell proliferation through in situ production in human thymoma.

PURPOSE: We showed previously estrogen receptor (ER) alpha as an independent prognostic marker in human thymoma. Estrogen sulfotransferase (EST), steroid sulfatase (STS), 17beta-hydroxysteroid dehydrogenase (17beta-HSD), and aromatase are considered to play important roles in hormone metabolism of estrogen-dependent tumors. EXPERIMENTAL DESIGN: We examined estrogen production using primary cultures of human thymoma epithelial cells (TEC), intratumoral estradiol (E(2)) concentrations, and status of these enzymes above using immunohistochemistry or semiquantitative reverse transcription-PCR. We then correlated these findings with clinicopathologic variables and/or clinical outcome in 132 patients. RESULTS: E(2) inhibited cell proliferation via ERalpha in TEC, which synthesized estrone and E(2). Intratumoral E(2) concentrations were inversely correlated with EST, positively correlated with STS or 17beta-HSD type 1, and significantly higher in lower-grade or early-stage thymoma. EST status was positively correlated with tumor size, clinical stage, histologic differentiation, and Ki-67 labeling index and significantly associated with adverse clinical outcome and turned out to be a potent independent prognostic factor. STS and/or 17beta-HSD type 1 status was inversely correlated with Ki-67 labeling index and associated with lower histologic grade or early clinical stages. CONCLUSIONS: E(2) inhibits proliferation of TEC through ERalpha, which suggests that E(2) may be effective in treatment of thymoma, especially inoperable tumor, possibly through suppressing its cell proliferation activity. EST status is a potent prognostic factor in thymoma through inactivating estrogens. In situ estrogen synthesis through intracrine mechanism therefore may play important roles in tumorigenesis and/or development of thymoma through regulation of cell proliferation in an intracrine manner.

Urocortin 1, urocortin 3/stresscopin, and corticotropin-releasing factor receptors in human adrenal and its disorders.

CONTEXT: Urocortin 1 (Ucn1) and urocortin 3 (Ucn3)/stresscopin are new members of the corticotropin-releasing factor (CRF) neuropeptide family. Ucn1 binds to both CRF type 1 (CRF1) and type 2 receptors (CRF2), whereas Ucn3 is a specific agonist for CRF2. Recently, direct involvement of the locally synthesized CRF family in adrenocortical function has been proposed. OBJECTIVE, DESIGN, AND SETTING: We examined in situ expression of Ucn and CRF receptors in nonpathological human adrenal gland and its disorders using immunohistochemistry and mRNA in situ hybridization. RESULTS: Ucn immunoreactivity was localized in the cortex and medulla of nonpathological adrenal glands. Ucn1 immunoreactivity was marked in the medulla, whereas Ucn3 was immunostained mostly in the cortex. Both CRF type 1 and CRF2 were expressed in the cortex, particularly in the zonae fasciculata and reticularis but very weakly or undetectably in the medulla. Immunohistochemistry in serial tissue sections with mirror images revealed that both Ucn3 and CRF2 were colocalized in more than 85% of the adrenocortical cells. mRNA in situ hybridization confirmed these findings above. In fetal adrenals, Ucn and CRF receptors were expressed in both fetal and definitive zones of the cortex. Ucn and CRF receptors were all expressed in the tumor cells of pheochromocytomas, adrenocortical adenomas, and carcinomas, but its positivity was less than that in nonpathological adrenal glands, suggesting that Ucn1, Ucn3, and CRF receptors were down-regulated in these adrenal neoplasms. CONCLUSIONS: Ucn1, Ucn3, and CRF receptors are all expressed in human adrenal cortex and medulla and may play important roles in physiological adrenal functions.

Analysis for localization of steroid sulfatase in human tissues.

Human steroid sulfatase (STS) is an enzyme that hydrolyzes several sulfated steroids, such as estrone sulfate, dehydroepiandrosterone sulfate, and cholesterol sulfate, and results in the production of active substances. STS has been demonstrated in human breast cancer tissues and is considered to be involved in intratumoral estrogen production. It is very important to analyze the cellular distribution of STS with accuracy in human tissues in order to obtain a better understanding of the biological significance of STS. Therefore, this chapter describes several morphological approaches used to study the localization of STS, including immunohistochemistry, mRNA in situ hybridization, and laser capture microdissection/reverse transcription-polymerase chain reaction, in human tissues.

Steroid sulfatase and estrogen sulfotransferase in human endometrial carcinoma.

PURPOSE: Intratumoral metabolism and synthesis of estrogens are considered to play important roles in the pathogenesis and/or development of human endometrial carcinoma. Steroid sulfatase hydrolyzes biologically inactive estrogen sulfates to active estrogens, whereas estrogen sulfotransferase sulfonates estrogens to estrogen sulfates. However, the status of steroid sulfatase and/or estrogen sulfotransferase in human endometrial carcinoma has not been examined. EXPERIMENTAL DESIGN: We first examined the expression of steroid sulfatase and estrogen sulfotransferase in 6 normal endometrium and 76 endometrial carcinoma using immunohistochemistry to elucidate the possible involvement of steroid sulfatase and estrogen sulfotransferase. We then evaluated the enzymatic activity and the semiquantitative analysis of mRNA using reverse transcription-PCR in 21 endometrial carcinomas. We correlated these findings with various clinicopathological parameters including the expression of aromatase, 17beta-hydroxysteroid dehydrogenase type 1 and type 2. RESULTS: Steroid sulfatase and estrogen sulfotransferase immunoreactivity was detected in 65 of 76 (86%) and 22 of 76 (29%) cases, respectively. Results of immunoreactivity for steroid sulfatase and estrogen sulfotransferase were significantly correlated with those of enzymatic activity and semiquantitative analysis of mRNA. No significant correlations were detected among the expression of the enzymes involved in intratumoral estrogen metabolism. There was a significant correlation between steroid sulfatase/estrogen sulfotransferase ratio and clinical outcomes of the patients. However, there were no significant differences between steroid sulfatase or estrogen sulfotransferase and estrogen receptor, progesterone receptor, Ki67, histologic grade, or clinical outcomes of the patients. CONCLUSIONS: Results of our study demonstrated that increased steroid sulfatase and decreased estrogen sulfotransferase expression in human endometrial carcinomas may result in increased availability of biologically active estrogens and may be related to estrogen-dependent biological features of carcinoma.

Role of steroid sulfatase in local formation of estrogen in post-menopausal breast cancer patients.

More than two-thirds of breast cancers occur in post-menopausal women, and depend on the estrogens for their proliferation and survival. For the treatment of estrogen-dependent breast cancers, two major treatment options are now available. One is selective estrogen receptor modulator (SERM) such as Tamoxifen and another is aromatase inhibitor such as Anastrozole, Letrozole and Exemestane, which reduce local in situ formation of estrogens. Although these therapies are clinically active for advanced and early breast cancers, de novo and/or acquired resistance to SERM and/or aromatase inhibitors are also clinical problem. Recent studies suggest that local formation of estrogens in the breast tumors is more important than circulating estrogen in plasma for the growth and survival of estrogen-dependent breast cancer in post-menopausal women. The rationale for the importance of local formation of estrogens is based on the following evidences. Estradiol (E2) levels in breast tumors are equivalent to those of pre-menopausal patients, although plasma E2 levels are 50-fold lower after menopause. E2 concentrations in breast tumors of post-menopausal women are 10-40 times higher than serum level. Biosynthesis of estrogens in breast tumors tissues occurs via two major different routes, one is aromatase pathway and another is steroid-sulfatase (STS) pathway. Whereas many studies has been reported about aromatase inhibitor and its clinical trial results in breast cancer patients, limited information are available regarding to other estrogen regulating enzymes including STS, its role in breast tumors and STS inhibitors. STS is the enzyme that hydrolyses estrone 3-sulfate (E1S) and dehydroepiandrosterone-sulfate (DHEA-S) to their active un-sulfoconjugated forms, thereby stimulating the growth and survival of estrogen-dependent breast tumors. It has been well known that E1S level are much higher than E2 level both in plasma and tumor of post-menopausal patients. Recent reports show that more than 80% of breast tumors are stained with anti-STS antibody and the expression of STS is an independent prognostic factor in breast cancer. Taking these findings into consideration, local formation of estrogens could be partially synthesized from large amount of E1S by STS, which exist in breast cancer. On the other hand, aromatase localizes in stroma and adipocyte surrounding breast cancer. Furthermore, since estrogen formation from E1S and DHEA-S (STS pathway) cannot be blocked by aromatase inhibitors, STS is thought to be a new molecular target for the treatment of estrogen-dependent tumor post-SERM and/or aromatase inhibitors. In this symposium, these recent rationale for the importance of STS in post-menopausal breast cancer patients is reviewed as well as STS inhibitor.

Steroid sulfatase and estrogen sulfotransferase in normal human tissue and breast carcinoma.

Steroid sulfatase (STS) hydrolyzes inactive estrone sulfate (E1-S) to estrone (E1), while estrogen sulfotransferase (EST; SULT 1E1 or STE gene) sulfonates estrogens to estrogen sulfates. They are considered to play important roles in the regulation of local estrogenic actions in various human tissues, however, their biological significance remains largely unknown. Therefore, we examined the expression of STS and EST in non-pathologic human tissues and breast carcinomas. STS expression was very weak except for the placenta, while EST expression was markedly detected in various tissues examined. In breast carcinoma tissues, STS and EST immunoreactivity was detected in carcinoma cells in 74 and 44% of cases, respectively, and was significantly associated with their mRNA levels and enzymatic activities. STS immunoreactivity was significantly correlated with the tumor size, and an increased risk of recurrence. EST immunoreactivity was inversely correlated with the tumor size or lymph node status. Moreover, EST immunoreactivity was significantly associated with a decreased risk of recurrence or improved prognosis. Our results suggest that EST is involved in protecting various peripheral tissues from excessive estrogenic effects. In the breast carcinoma, STS and EST are suggested to play important roles in the regulation of in situ estrogen production in the breast carcinomas.

Steroid sulfatase and estrogen sulfotransferase in the atherosclerotic human aorta.

Various epidemiological studies have demonstrated a relatively low incidence of cardiovascular events in premenopausal women and its marked increment after menopause. In addition, estrogens have been postulated to exert direct anti-atherogenic effects via binding to estrogen receptors in vascular smooth muscle cells (VSMCs). However, not all postmenopausal women develop atherosclerosis despite decreased levels of serum estrogen. Therefore, we believe it is important to examine the status of estrogen metabolism in situ in the human cardiovascular system. Estrone sulfate (E1S) is a major circulating plasma estrogen that is converted into the biologically active estrogen, estrone (E1) by steroid sulfatase (STS). E1 is also sulfated and reverted into E1S by estrogen sulfotransferase (EST). These two enzymes have recently been shown to play important roles in the in situ estrogen actions of estrogen-dependent human tissues and various sex steroid-dependent tumors. STS and EST, however, have not been studied in detail in the human vascular system associated with atherosclerotic changes. In the present study, we evaluated the relative abundance of STS- and EST-immunoreactive protein and mRNA expression in human aorta using immunohistochemistry and reverse transcription followed by quantitative polymerase chain reaction in addition to enzyme activity. STS expression levels were found to be significantly higher in the VSMCs obtained from female aortas with mild atherosclerotic changes than in those with severe atherosclerotic changes and in male aortas regardless of atherosclerotic changes. EST expression levels in the VSMCs of these aortas, however, were significantly higher in female aortas with severe atherosclerotic changes and in male aortas than in female aortas with mild atherosclerotic changes. We believe it is important to examine factors regulating the expression and activity of these estrogen-metabolizing enzymes in the human aorta. Various cytokines have been proposed to function as regulators of these enzymes in other tissues. In the present study, we studied the effects of interleukin (IL)-1beta, known to be produced in human atherosclerotic lesions, on the expression of these enzymes using cultured human VSMCs originally obtained from a female patient. IL-1beta markedly inhibited the expression of STS mRNA and enzyme activity, but stimulated the expression of EST mRNA and enzyme activity. In addition, IL-1beta also reduced E2 production from E1S and E1 in VSMCs. Results from the present study seem to suggest that the expression levels of both STS and EST mRNA and activity may be significantly associated with the degree of atherosclerotic changes in the female aorta, which may be related to cytokines produced in situ, such as IL-1beta, in human atherosclerotic lesions.

Estrogen sulfotransferase and steroid sulfatase in human breast carcinoma.

Estrogen sulfotransferase (EST; SULT 1E1 or STE gene) sulfonates estrogens to inactive estrogen sulfates, whereas steroid sulfatase (STS) hydrolyzes estrone sulfate to estrone. Both EST and STS have been suggested to play important roles in regulating the in situ production of estrogens in human breast carcinoma tissues. However, the expression of EST has not been examined in breast carcinoma tissues, and the biological significance of EST and STS remains unknown. Therefore, in this study, we examined the expression of EST and STS in 35 specimens of human breast carcinoma tissues using immunohistochemistry, reverse transcription-PCR (RT-PCR), and enzymatic assay. EST and STS immunoreactivity was also correlated with various clinicopathological parameters, including prognosis to examine the biological significance of these enzymes in 113 breast carcinomas. EST and STS immunoreactivity was detected in carcinoma cells and significantly associated with their mRNA levels (P = 0.0027 and 0.0158, respectively), as measured by RT/real-time PCR, and enzymatic activities (P = 0.0005 and 0.0089, respectively) in 35 breast carcinomas. In breast cancer tissues examined by laser capture microdissection/RT-PCR analyses, the mRNA for EST was localized in both carcinoma and intratumoral stromal cells, whereas that of STS was detected only in carcinoma cells. Of the 113 invasive ductal carcinomas examined in this study, EST and STS immunoreactivity was detected in 50 and 84 cases (44.2 and 74.3%), respectively. In these cases, EST immunoreactivity was inversely correlated with tumor size (P = 0.003) or lymph node status (P = 0.0027). In contrast, STS immunoreactivity was significantly correlated with tumor size (P = 0.0047). Moreover, EST immunoreactivity was significantly associated with a decreased risk of recurrence or improved prognosis by both uni (P = 0.0044, and 0.0026, respectively) and multivariate (P = 0.0429 and 0.0149, respectively) analyses. STS immunoreactivity, however, was significantly associated with an increased risk of recurrence (P = 0.0118) and worsened prognosis (P = 0.0325) by univariate analysis. Results from our present study suggest that immunoreactivities for both EST and STS are associated with their mRNA level and enzymatic activity and that EST immunoreactivity is considered to be a potent prognostic factor in human breast carcinoma.

Systemic distribution of steroid sulfatase and estrogen sulfotransferase in human adult and fetal tissues.

Estrogens play a key role in various target tissues. Enzymes involved in the biosynthesis and metabolism of these sex steroids also regulate estrogenic actions in these tissues. Estrone sulfate (E1S) is a major circulating plasma estrogen that is converted into the biologically active estrogen, estrone (E1), by steroid sulfatase (STS). E1 is also sulfated and reverted into E1S by estrogen sulfotransferase (EST). These two enzymes have recently been shown to play important roles in the in situ estrogen actions of various sex steroid-dependent human tumors. However, the distribution of STS and EST in normal adult and fetal human tissues remains largely unknown. Therefore, in this study, in addition to examining the tissue distribution of both STS and EST mRNA in human adult and fetal tissues using RT followed by quantitative PCR, we studied the activity of these enzymes using (3)H-labeled E1/E1S as substrates in the homogenates of various human adult tissues. We also examined the localization of STS and EST protein in human adult and fetal tissues using immunohistochemistry, and that of EST mRNA in the adult kidney using laser dissection microscopy and PCR. STS mRNA, enzyme activity, and immunoreactivity were either absent or detected at very low levels in all adult and fetal tissues examined in this study. EST mRNA expression, however, was detected in all of the tissues examined, except for adult spleen and pancreas. EST enzyme activities were consistent with those of mRNA expression in the great majority of the tissues examined. Marked EST immunoreactivity was detected in hepatocytes, adrenal gland (adult, zona fasciculate to the reticularis; fetus, fetal zone), and epithelial cells of the gastrointestinal tract, smooth muscle cells of the tunica media in aorta, Leydig cells of the testis, and syncytiotrophoblast of the placenta. Patterns of EST immunolocalization were similar between adult and fetal human tissues, but EST immunoreactivity was detected in the urinary tubules of adult kidney, whereas in the fetal kidney, it was localized in the interstitial cells surrounding the urinary tubules. In the adult kidney, the presence of EST mRNA was also confirmed in the cells of urinary tubules using laser dissection microscopy and RT-PCR. Although the number of human tissues available for examination in this study was limited, our results suggest that between the enzymes involved in estrogen activation or inactivation, EST and not STS is the more widely expressed enzyme in various peripheral tissues in humans. We speculate that EST may play an important role in protecting peripheral tissues from possible excessive estrogenic effects.