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Srilatha Swami, Aruna V Krishnan, Lihong Peng, Johan Lundqvist, and David Feldman

Calcitriol (1,25-dihydroxyvitamin D3), the hormonally active metabolite of vitamin D, exerts its anti-proliferative activity in breast cancer (BCa) cells by multiple mechanisms including the downregulation of the expression of estrogen receptor α (ER). We analyzed an ∼3.5 kb ER promoter sequence and demonstrated the presence of two potential negative vitamin D response elements (nVDREs), a newly identified putative nVDRE upstream at −2488 to −2473 bp (distal nVDRE) and a previously published sequence (proximal nVDRE) at −94 to −70 bp proximal to the P1 start site. Transactivation analysis using ER promoter deletion constructs and heterologous promoter–reporter constructs revealed that both nVDREs functioned to mediate calcitriol transrepression. In the electrophoretic mobility shift assay, the vitamin D receptor (VDR) showed strong binding to both nVDREs in the presence of calcitriol, and the chromatin immunoprecipitation assay demonstrated the recruitment of the VDR to the distal nVDRE site. Mutations in the 5′ hexameric DNA sequence of the distal nVDRE resulted in the loss of calcitriol-mediated transrepression and the inhibition of protein–DNA complex formation, demonstrating the importance of these nucleotides in VDR DNA binding and transrepression. A putative nuclear factor-Y (NFY) binding site, identified within the distal nVDRE, led to the findings that NFY bound to the distal nVDRE site interfered with the binding of the VDR at the site and reduced calcitriol-mediated transrepression. In conclusion, the ER promoter region contains two negative VDREs that act in concert to bind to the VDR and both nVDREs are required for the maximal inhibition of ER expression by calcitriol. The suppression of ER expression and estrogen-mediated signaling by calcitriol in BCa cells suggests that vitamin D may be useful in the treatment of ER+ BCa.

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R A Janknegt and T A Boon

Abstract

Hormonal therapy alone for metastatic prostate cancer is effective in reducing tumour growth for a limited period of time. Progression of the tumour after an initial good response is due to the development of hormone-resistant cells. It is not known whether hormone-resistant cells develop as a mutation of the original hormone-sensitive cell later on in the progress of the disease or from early on as a separate entity. Chemotherapy has been used as second-line treatment with an average gain of only a few weeks over hormonal palliation. No studies of primary treatment with chemotherapy alone have been done. Some combined hormo-chemotherapy studies have shown some improvement in time to progression but not in survival

We have performed a multicentre randomized study comparing hormonal treatment (orchiectomy) versus hormo-chemotherapy (orchiectomy plus a high dosage of estramustin). This included 419 patients over 2 years: 281 M+ patients and 108 MO N+. The dosage of estramustin (Estracyt) was 840 mg/day (first month) and 560 mg/day thereafter.

The results showed that, in the M+ patients, median time to progression differed by 6 months for the hormo-chemotherapy-treated group (P=0.02). Median time to survival was not different in both groups, but multivariate analysis showed a 3-month difference in the group younger than 70 years in favour of the estramustin-treated group (P=0.0007). In the MO N+ patients, growth was slower. In both groups median time to progression and survival had not been reached after 35 months. Toxicity in the orchiectomy plus estramustin-treated group was low: there were no cardiovascular side-effects. Nausea was a problem during the first 4 weeks.

In our series pain and alkaline phosphatase were the main prognostic factors.

In conclusion, primary hormo-chemotherapy combined with estramustin showed a significant difference in time to progression (quality of life) but a limited survival benefit for a specific age group. In a future study we shall study patients with poor prognostic factors only.

Endocrine-Related Cancer (1996) 3 285-292

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Vera Cappelletti, Luigi Celio, Emilio Bajetta, Arianna Allevi, Raffaella Longarini, Patrizia Miodini, Raffaella Villa, Alessandra Fabbri, Luigi Mariani, Riccardo Giovanazzi, Emanuele Galante, Marco Greco, and Maria Grazia Daidone

It has been proposed that knowledge of estrogen receptor β (ER-β) expression may refine estrogen receptor α (ER-α) predictivity of response to endocrine therapy. We challenged this hypothesis in ERα-positive breast cancers subjected to preoperative antiestrogen treatment. Forty-seven elderly (≥65 years old) women with nonmetastatic, ER-α-positive (by immunohistochemistry) primary breast cancers (> 2 cm in diameter) entered a neoadjuvant hormone therapy protocol (60 mg/day toremifene for 3 months). ER-α and ER-β (ERs) mRNA was determined by semiquantitative RT-PCR, before (on core needle biopsy) and after (on surgical specimens) neoadjuvant treatment. Study end points included: (1) relation between treatment response and ER mRNA expression; and (2) changes in ER expression after treatment. The response was clinically assessed as tumor size change at the end of the preoperative treatment. ER mRNA expression was assessable before and after treatment in 38 and 20 cases respectively. ER-β was co-expressed with ER-α at variable levels and significantly correlated only with progesterone receptor (P = 0.0285). Objective clinical response, including patients with minor change (≥25–<50% tumor shrinkage after treatment), was documented in 68.4% of cases and was independent of ER-β levels or changes. ER-α levels were higher in tumors from patients in complete remission than in those from women achieving partial response or minor change compared with non-responsive patients (median expression values: 801 versus 516 versus 320 arbitrary units) and were consistently down-regulated by preoperative treatment. We conclude that in this elderly patient population with ER-α-positive tumors, ER-β mRNA was neither predictive of response to preoperative toremifene nor provided additional information to the knowledge of ER-α mRNA levels, which, conversely, were directly correlated with likelihood of response.

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S Taucher, M Rudas, M Gnant, K Thomanek, P Dubsky, S Roka, T Bachleitner, D Kandioler, C Wenzel, G Steger, M Mittlböck, and R Jakesz

The objective of this analysis was to determine the accuracy of steroid receptor measurement in large core needle biopsies compared with surgically removed specimens and the influence of preoperative chemotherapy on hormone receptor status. We consecutively performed 722 large core needle biopsies in palpable lesions of the breast. The diagnosis of breast cancer was confirmed upon biopsy in 450 patients; 236 women underwent immediate surgery, and 214 patients received preoperative chemotherapy. We assessed estrogen (ER) and progesterone receptor (PR) in biopsy tissue and surgically removed specimens and calculated accuracy, sensitivity, specificity, the weighted kappa value and Spearman's rank correlation. The modulation of steroid receptor status in preoperatively treated patients was tested by Cochran-Mantel-Haenszel statistics. The accuracy of ER evaluation in the biopsy material of patients without intervening chemotherapy was 91%, sensitivity and specificity were 94% and 80% respectively. Accuracy, sensitivity and specificity were 86% in patients treated preoperatively. In terms of PR assessment, we obtained slightly inferior results: accuracy, sensitivity and specificity were 80%, 73% and 85% respectively in patients without preoperative treatment, and 79%, 48% and 92% respectively in patients undergoing preoperative therapy. Following preoperative chemotherapy, patients showed a significant increase in ER-negative (P=0.02) and PR-negative (P=0.0005) measurements. We have concluded from our results that ER and PR receptor measurement in core needle biopsy is a reliable basis in clinical practice for selecting patients for neoadjuvant endocrine treatment. Preoperative cytotoxic chemotherapy induced a significant extent of variation in the steroid receptor expression of breast cancer cells.

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Sudipan Karmakar, Estrella A Foster, Julia K Blackmore, and Carolyn L Smith

Elevated expression of steroid receptor coactivator-3 (SRC-3), a member of the p160 family of nuclear receptor coactivators, has been implicated in tamoxifen resistance of breast tumors while the involvement of the two other members of this family, SRC-1 and SRC-2, is less well characterized. In this study, using small interfering RNA-based silencing, the role of each SRC coactivator in the growth of the LCC2 estrogen-independent and tamoxifen-resistant breast cancer cell line was evaluated. The loss of SRC-1, SRC-2, or SRC-3 did not significantly alter LCC2 proliferation or cell cycle distribution of 4-hydroxytamoxifen- versus vehicle-treated cells. However, depletion of SRC-2 and SRC-3, but not SRC-1, decreased basal cell proliferation and increased apoptosis. Cell cycle analyses further illustrated the divergent contributions of SRC-2 and SRC-3 with depletion of the former increasing the percentage of cells in the G0G1 and sub-G0G1 phases of cell cycle yet maintaining sensitivity to estradiol and ICI 182 780 antiestrogen, while SRC-3 depletion increased cells in the sub-G0G1 phase and ablated response to estrogen receptor α (ERα) ligands. Surprisingly, the effects of SRC coactivator depletion on ERα transcriptional activity, as measured by luciferase reporter gene, did not correspond to the observed effects on proliferation (e.g. SRC-1 knockdown increases ERα activity). Collectively, these data indicate that SRC control of basal and hormone-regulated proliferations is not solely mediated by ERα, and suggest that targeting growth inhibition by disrupting SRC-2 and SRC-3 function may be an effective approach to inhibit the growth of tamoxifen-resistant breast cancer.

Free access

S E Bulun, K Zeitoun, K Takayama, L Noble, D Michael, E Simpson, A Johns, M Putman, and H Sasano

Estrogen is the most important known factor that stimulates the growth of endometriosis. Estrogen delivery to endometriotic implants was classically viewed to be only via the circulating blood in an endocrine fashion. We recently uncovered an autocrine positive feedback mechanism, which favored the continuous production of estrogen and prostaglandin (PG)E2 in the endometriotic stromal cells. The enzyme, aromatase, is aberrantly expressed in endometriotic stromal cells and catalyzes the conversion of C19 steroids to estrogens, which then stimulate cyclooxygenase-2 to increase the levels of PGE2. PGE2, in turn, is a potent inducer of aromatase activity in endometriotic stromal cells. Aromatase is not expressed in the eutopic endometrium. Aromatase expression in endometriosis and its inhibition in eutopic endometrium are controlled by the competitive binding of a stimulatory transcription factor, steroidogenic factor-1, and an inhibitory factor, chicken ovalbumin upstream promoter-transcription factor to a regulatory element in the aromatase P450 gene promoter. In addition, we find that endometriotic tissue is deficient in 17beta-hydroxysteroid dehydrogenase type 2, which is normally expressed in eutopic endometrial glandular cells and inactivates estradiol-17beta to estrone. This deficiency is another aberration that favors higher levels of estradiol-17beta in endometriotic tissues in comparison with the eutopic endometrium. The clinical relevance of local aromatase expression in endometriosis was exemplified by the successful treatment of an unusually aggressive form of recurrent endometriosis in a postmenopausal woman using an aromatase inhibitor.

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S H Safe

Sir, This paper (Safe & McDougal 1997) briefly summarized a conference presentation (Current Topics in Breast Cancer Research, Cambridge, 1996) which focused primarily on organochlorine estrogens/antiestrogens (the major focus) and not on the research studies by Drs Bradlow, Telang and co-workers. Nevertheless, seven references to their research were included. This group has published several excellent studies on 2- and 16α-hydroxylation of 17β-estradiol (E2) and their possible role in various cancers. Based on results of our previous studies on the induction of CYP1A1 and related activities in MCF-7 cells (e.g. Harris et al. 1989, Chaloupka et al. 1992, Arellano et al. 1993; Moore et al. 1993, 1994, Liu et al. 1994), we reinvestigated the influence of mammary carcinogens and anticarcinogens on metabolism of E2 in this cell line. Ongoing studies in my laboratory showed that the mammary carcinogen benzo-[a]pyrene (BaP) induced CYP1A1 in MCF-7 cells and we
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H Yamashita, M Nishio, Y Ando, Z Zhang, M Hamaguchi, K Mita, S Kobayashi, Y Fujii, and H Iwase

Constitutively activated signal transducers and activators of transcription (Stats), in particular Stat3 and Stat5, have been demonstrated to directly contribute to oncogenesis by stimulating cell proliferation and preventing apoptosis in various cancers. Stat3 is essential in mammary gland epithelial cell apoptosis and involution, whereas Stat5 is well established as a key factor in mammary epithelial cell growth and differentiation. Crosstalk between Stats and estrogen receptor (ER) has been demonstrated by several laboratories and we have focused on the role of Stat5 in ER-positive breast cancer. Using immunohistochemical techniques, we examined the expression of Stat3 and Stat5 in 517 human breast cancer tissues and analyzed their significance for prognosis and prediction of response to endocrine therapy. Stat5 expression was significantly correlated with histological grade (P < 0.0001), ER (P = 0.02), and progesterone receptor (P = 0.026) expression. There was no difference between Stat3 expression and clinicopathological factors. In 346 patients with ER-positive breast cancer, patients with Stat5 positive tumors had significantly increased overall survival (P = 0.0009) in multivariate analysis. There were 70 patients who received endocrine therapy as first-line treatment for metastatic breast cancer at relapse. The patients whose primary breast tumors were Stat5 positive, had significantly better response to endocrine therapy (P = 0.04), and longer survival after relapse (P = 0.0003), than those whose tumors were Stat5 negative. The present study demonstrates for the first time that Stat5 is a predictive factor for endocrine therapy response and a strong prognostic molecular marker in ER-positive breast cancer. Our data suggest that the expression of Stat5 is helpful in selecting patients who may benefit from endocrine therapy.

Free access

N Biglia, E Defabiani, R Ponzone, L Mariani, D Marenco, and P Sismondi

Breast carcinoma is the most frequent tumor in the female population. Many factors can influence the risk of breast cancer; some of them, such as old age and breast cancer 1/2 (BRCA1/BRCA2) gene mutations, are associated with a fourfold increase in risk. A previous diagnosis of atypical ductal or lobular hyperplasia or having a first-degree relative with a carcinoma are factors associated with a two- to fourfold increase in risk. A relative risk between 1 and 2 is associated with longer exposure to endogenous hormones as a result of early menarche, late menopause and obesity, or with recent and prolonged use of hormone replacement therapy (HRT) or with behavioural factors such as high alcohol and fat intake. Is it possible to modify breast cancer risk in postmenopausal women? Risk factors related to lifestyle can be changed, even if it is not clear whether modifying these behavioural factors during the postmenopausal period will influence the overall breast cancer risk. For instance, the influence of exogenous hormones throughout life (both oral contraceptives and HRT) should be evaluated according to the individual risk-benefit ratio. The problem is even more complex for women who carry genetic mutations and for those who have close relatives with breast cancer, who may be candidates for risk reduction strategies. Prophylactic bilateral mastectomy is still controversial, but is frequently offered to or requested by this group of women and may be indicated in BRCA1/BRCA2 carriers. Chemoprevention with tamoxifen and with the new selective estrogen receptor modulators, namely raloxifene, is very promising and deserves a thorough discussion for all high-risk women.

Free access

Takashi Suzuki, Akio Inoue, Yasuhiro Miki, Takuya Moriya, Jun-ichi Akahira, Takanori Ishida, Hisashi Hirakawa, Yuri Yamaguchi, Shin-ichi Hayashi, and Hironobu Sasano

Early growth responsive gene 3 (EGR3) is a zinc-finger transcription factor and plays important roles in cellular growth and differentiation. We recently demonstrated estrogen-mediated induction of EGR3 in breast carcinoma cells. However, EGR3 has not yet been examined in breast carcinoma tissues and its significance remains unknown. Therefore, in this study, we examined biological functions of EGR3 in the breast carcinoma by immunohistochemistry, in vitro study, and nude mouse xenograft model. EGR3 immunoreactivity was detected in carcinoma cells in 99 (52%) out of 190 breast carcinoma tissues and was associated with the mRNA level. EGR3 immunoreactivity was positively associated with lymph node status, distant metastasis into other organs, estrogen receptor α, or EGR3 immunoreactivity in asynchronous recurrent lesions in the same patients, and was negatively correlated with tubule formation. EGR3 immunoreactivity was significantly associated with an increased risk of recurrence and adverse clinical outcome by both uni- and multivariate analyses. Egr3-expressing transformant cell lines derived from MCF-7 Tet-Off cells (Eg-10 and Eg-11) significantly enhanced the migration and invasion properties according to the treatment of doxycyclin, but did not significantly change the cell proliferation. Moreover, Eg-11 cells injected into athymic mice irregularly invaded into the adjacent peritumoral tissues, although Clt-7, which was stably transfected with empty vector as a control, demonstrated a well-circumscribed tumor. Eg-11 cells were significantly associated with invasive components and less tubule formation in the xenograft model. These results suggest that EGR3 plays an important role in estrogen-meditated invasion and is an independent prognostic factor in breast carcinoma.