Inhibition of estrogen-stimulated growth of uterine leiomyomas by selective estrogen receptor modulators

Current and Emerging Treatment Options for Uterine Fibroids

Uterine fibroids are the most common benign neoplasm of the female reproductive tract in reproductive age women. Their prevalence is age dependent and can be detected in up to 80% of women by the age of 50 years. Patients affected by uterine fibroids may experience a significant physical, emotional, social, and financial toll as well as losses in their quality of life. Unfortunately, curative hysterectomy abolishes future pregnancy potential, while uterine-sparing surgical and radiologic alternatives are variously associated with reduced long-term reproductive function and/or high tumor recurrence rates. Recently, pharmacological treatment against uterine fibroids have been widely considered by patients to limit uterine fibroid-associated symptoms such as heavy menstrual bleeding. This hormonal therapy seemed effective through blocking the stimulatory effects of gonadal steroid hormones on uterine fibroid growth. However, they are contraindicated in women actively pursuing pregnancy and otherwise effective only during use, which is limited because of long-term safety and other concerns. Accordingly, there is an urgent unmet need for safe, durable, and fertility-compatible non-surgical treatment options for uterine fibroids. In this review article, we cover the current pharmacological treatments for uterine fibroids including their comparable efficacy and side effects as well as emerging safe natural compounds with promising anti-uterine fibroid effects.

Effect of the Aqueous Extract of Ganoderma lucidum on the Haematology, Oestradiol, Cholesterol and Protein Levels of Wistar Rats Fed with Monosodium Glutamate

Monosodium glutamate (MSG) at high concentration has been reported to alter the physiological and biochemical states of animals and humans. Ganoderma lucidum (G. lucidum) is a polypore mushroom reported to possess many medicinal attributes such as anticholesterolemia and the control of hormonal disorders. The present study investigated the effect of water extract of G. lucidum in the changes of haematology, oestradiol, cholesterol and protein levels of Wistar rats induced by MSG. Haematological analysis was determined from plasma, while oestrogen, serum total protein and cholesterol levels were determined from the serum of the rats. Results showed that MSG significantly raised the level of oestrogen (62.5 ± 0.28 pg/mL) in the rats which was significantly reduced in the rats fed with MSG for 30 days before treating them with the extracts of G. lucidum (30.85 ± 12.94 pg/mL–44.15 ± 0.92 pg/mL) and in rats fed concurrently with MSG and G. lucidum. The cholesterol level was significantly reduced in the rats treated with MSG and G. lucidum (200 mg/kg) concurrently compared to rats fed with MSG alone. The white blood cell (WBC) and red blood cell (RBC) levels were within normal in rats fed with both MSG and G. lucidum as in the control group while the rats fed with MSG only had low WBC, neutrophil (NEU) and RBC. This could imply that G. lucidum ameliorates the effect of MSG on serum oestrogen, serum cholesterol, WBCs, NEU, platelets and lymphocytes.

Role of DNA damage and repair mechanisms in uterine fibroid/leiomyomas: a review

There has been a significant annual increase in the number of cases of uterine leiomyomas or fibroids (UF) among women of all races and ages across the world. A fortune is usually spent by the healthcare sector for fibroid-related treatments and management. Molecular studies have established the higher mutational heterogeneity in UF as compared to normal myometrial cells. The contribution of DNA damage and defects in repair responses further increases the mutational burden on the cells. This in turn leads to genetic instability, associated with cancer risk and other adverse reproductive health outcomes. Such and many more growing bodies of literature have highlighted the genetic/molecular, biochemical and clinical aspects of UF; none the less there appear to be a lacuna bridging the bench to bed gap in addressing and preventing this disease. Presented here is an exhaustive review of not only the molecular mechanisms underlying the predisposition to the disease but also possible strategies to effectively diagnose, prevent, manage, and treat this disease.

Hormone therapy in menopausal women with fibroids: is it safe?

Menopause is an important transition in the life of women. It has been estimated that by the year 2030, worldwide 1.2 billion women will be menopausal. The most bothersome symptoms of menopause are believed to be due to declines in estrogen levels in postmenopausal women. Thus, hormone therapy is an effective treatment option for menopausal women, although prolonged use of hormone therapy is associated with a slightly increased risk of breast cancer, thromboembolism, and stroke. A literature search for studies evaluating the effects of hormone therapy in menopausal women with asymptomatic fibroids demonstrated variable effects of hormone therapy on the volume and size of the fibroids. Some studies have demonstrated an increase in size of pre-existing asymptomatic fibroids and formation of new fibroids with higher doses of progestogen in combination therapy. The finding of low resistance index in uterine arteries of women with asymptomatic fibroids is associated with an increased risk of fibroid growth, and thus making the measurement of pulsatility index of uterine arteries a possible screening tool before initiating hormone therapy in menopausal women with fibroids. Although the effect of hormone treatment is variable and statistically insignificant in many cases, the newer selective estrogen receptor modulators having tissue-specific estrogen agonistic and antagonistic actions such as raloxifene have a favorable clinical profile and may be better alternatives in women with asymptomatic fibroids.

Endocrine-disrupting chemicals and uterine fibroids

Uterine fibroids are the most frequent gynecologic tumor, affecting 70% to 80% of women over their lifetime. Although these tumors are benign, they can cause significant morbidity and may require invasive treatments such as myomectomy and hysterectomy. Many risk factors for these tumors have been identified, including environmental exposures to endocrine-disrupting chemicals (EDCs) such as genistein and diethylstilbestrol. Uterine development may be a particularly sensitive window to environmental exposures, as some perinatal EDC exposures have been shown to increase tumorigenesis in both rodent models and human epidemiologic studies. The mechanisms by which EDC exposures may increase tumorigenesis are still being elucidated, but epigenetic reprogramming of the developing uterus is an emerging hypothesis. Given the remarkably high incidence of uterine fibroids and their significant impact on women's health, understanding more about how prenatal exposures to EDCs (and other environmental agents) may increase fibroid risk could be key to developing prevention and treatment strategies in the future.

Identification of a Sensitive Period for Developmental Programming That Increases Risk for Uterine Leiomyoma in Eker Rats

Epidemiological and experimental animal studies have shown that exposure to xenoestrogens during reproductive tract development reprograms target tissues, leading to increased disease risk later in adult life. To understand what defines the critical risk period for this effect, termed developmental programming, the authors assess the sensitivity of the female reproductive tract to developmental programming during various stages of neonatal development. Eker rats, which are predisposed to develop uterine leiomyoma because of a germ-line defect in the tuberous sclerosis complex 2 (Tsc-2) tumor suppressor gene, were exposed to the xenoestrogen diethylstilbestrol (DES) on either postnatal days 3 to 5, 10 to 12, or 17 to 19, 3 important periods of reproductive tract development and differentiation. Developmental programming was observed in both carrier (Tsc-2(Ek/+)) and wild-type (Tsc-2(+/+)) rats exposed to DES at days 3 to 5 and days 10 to 12 but not in rats exposed at days 17 to 19. Developmental programming resulted in increased tumor suppressor gene penetrance in Tsc-2(Ek/+) females relative to vehicle controls. In contrast, DES exposure at days 17 to 19 did not significantly increase the incidence of uterine leiomyoma in carrier females, indicating that the window of susceptibility had closed by this time. Gene expression analysis to determine what defined the susceptible (days 3-5 and days 10-12) versus resistant (days 17-19) periods revealed that in adult myometrium, expression of the estrogen-responsive genes calbindin D(9)K and progesterone receptor had been reprogrammed in females exposed to DES at days 3 to 5 and days 10 to 12 but not in those exposed at days 17 to 19. Reprogramming in response to DES exposure resulted in a hyperresponsiveness to ovarian hormones and could be prevented by ovariectomy prior to sexual maturity. Furthermore, in the neonatal uterus, DES was equally effective at inducing transcription of estrogen-responsive genes during both sensitive and resistant periods, indicating that resistance to developmental programming was not due to an inability of the estrogen receptor to transactivate gene expression. Interestingly, the resistant period coincided with the time at which reproductive tract tissues are exposed to endogenous estrogen, suggesting that target tissues are most vulnerable to developmental programming during the period in which they would normally be maintained in an estrogen-naïve state.

Proceedings from the Third National Institutes of Health International Congress on Advances in Uterine Leiomyoma Research: comprehensive review, conference summary and future recommendations

BACKGROUND Uterine fibroids are the most common gynecologic tumors in women of reproductive age yet the etiology and pathogenesis of these lesions remain poorly understood. Age, African ancestry, nulliparity and obesity have been identified as predisposing factors for uterine fibroids. Symptomatic tumors can cause excessive uterine bleeding, bladder dysfunction and pelvic pain, as well as associated reproductive disorders such as infertility, miscarriage and other adverse pregnancy outcomes. Currently, there are limited noninvasive therapies for fibroids and no early intervention or prevention strategies are readily available. This review summarizes the advances in basic, applied and translational uterine fibroid research, in addition to current and proposed approaches to clinical management as presented at the 'Advances in Uterine Leiomyoma Research: 3rd NIH International Congress'. Congress recommendations and a review of the fibroid literature are also reported. METHODS This review is a report of meeting proceedings, the resulting recommendations and a literature review of the subject. RESULTS The research data presented highlights the complexity of uterine fibroids and the convergence of ethnicity, race, genetics, epigenetics and environmental factors, including lifestyle and possible socioeconomic parameters on disease manifestation. The data presented suggest it is likely that the majority of women with uterine fibroids will have normal pregnancy outcomes; however, additional research is warranted. As an alternative to surgery, an effective long-term medical treatment for uterine fibroids should reduce heavy uterine bleeding and fibroid/uterine volume without excessive side effects. This goal has not been achieved and current treatments reduce symptoms only temporarily; however, a multi-disciplined approach to understanding the molecular origins and pathogenesis of uterine fibroids, as presented in this report, makes our quest for identifying novel targets for noninvasive, possibly nonsystemic and effective long-term treatment very promising. CONCLUSIONS The Congress facilitated the exchange of scientific information among members of the uterine leiomyoma research and health-care communities. While advances in research have deepened our knowledge of the pathobiology of fibroids, their etiology still remains incompletely understood. Further needs exist for determination of risk factors and initiation of preventive measures for fibroids, in addition to continued development of new medical and minimally invasive options for treatment.

Uterine-specific loss of Tsc2 leads to myometrial tumors in both the uterus and lungs

Lymphangioleiomyomatosis (LAM) is a rare disease characterized by proliferation of abnormal smooth-muscle cells in the lungs, leading to functional loss and sometimes lung transplantation. Although the origin of LAM cells is unknown, several features of LAM provide clues. First, LAM cells contain inactivating mutations in genes encoding Tsc1 or Tsc2, proteins that limit mTORC1 activity. Second, LAM tumors recur after lung transplantation, suggesting a metastatic pathogenesis. Third, LAM is found almost exclusively in women. Finally, LAM shares features with uterine leiomyomas, benign tumors of myometrial cells. From these observations, we proposed that LAM cells might originate from uterine leiomyomas containing Tsc mutations. To test our hypothesis, and to develop mouse models for leiomyoma and LAM, we targeted Tsc2 deletion primarily in uterine cells. In fact, nearly 100% of uteri from uterine-specific Tsc2 knockout mice developed myometrial proliferation and uterine leiomyomas by 12 and 24 weeks, respectively. Myometrial proliferation and mTORC1/S6 activity were abrogated by the mTORC1 inhibitor rapamycin or by elimination of sex steroid production through ovariectomy or aromatase inhibition. In ovariectomized Tsc2 null mice, mTORC1/S6 activity and myometrial growth were restored by estrogen but not progesterone. Thus, even without Tsc2, estrogen appears to be required for myometrial mTORC1/S6 signaling and proliferation. Finally, we found Tsc2 null myometrial tumors in lungs of older Tsc2 uterine-specific knockout females, suggesting that lung LAM-like myometrial lesions may indeed originate from the uterus. This mouse model may improve our understanding of LAM and leiomyomas and might lead to novel therapeutic strategies for both diseases.

Histone deacetylase 6 regulates estrogen receptor alpha in uterine leiomyoma

Histone deacetylase 6 (HDAC) 6 is a regulatory factor in the endocrine traffic network that controls growth factor receptor stability. Histone deacetylase 6 expression and its pathogenic role in the uterine leiomyoma have not been studied. Here, we demonstrated that there was a consistent pattern of increasing HDAC6 and estrogen receptor (ER) α expression in leiomyoma samples. For all individual cases, expression of HDAC6 in the normal myometrium or leiomyoma positively correlated with ERα expression. The spearman's rho (ρ) was .53 (P = .008) between HDAC6 and ERα in normal myometrium and, more significantly, the spearman rho was .80 (P < .001) between HDAC6 and ERα in leiomyoma. In ELT-3 leiomyoma cells, silencing HDAC6 expression substantially reduced ERα expression, lowered estrogen response, and inhibited ELT-3 cell growth. Our results, taken together, are the first to provide experimental evidence suggesting that HDAC6 may be an essential molecular therapeutic target in controlling leiomyoma growth.

Human uterine smooth muscle and leiomyoma cells differ in their rapid 17beta-estradiol signaling: implications for proliferation

Uterine leiomyomas, benign uterine smooth muscle tumors that affect 30% of reproductive-aged women, are a significant health concern. The initiation event for these tumors is unclear, but 17beta-estradiol (E2) is an established promoter of leiomyoma growth. E2 not only alters transcription of E2-regulated genes but also can rapidly activate signaling pathways. The aim of our study is to investigate the role of rapid E2-activated cytoplasmic signaling events in the promotion of leiomyomas. Western blot analysis revealed that E2 rapidly increases levels of phosphorylated protein kinase C alpha (PKC alpha) in both immortalized uterine smooth muscle (UtSM) and leiomyoma (UtLM) cell lines, but increases levels of phosphorylated ERK1/2 only in UtLM cells. Our studies demonstrate a paradoxical effect of molecular and pharmacological inhibition of PKC alpha on ERK1/2 activation and cellular proliferation in UtLM and UtSM cells. PKC alpha inhibition decreases levels of phosphorylated ERK1/2 and proliferation in UtLM cells but raises these levels in UtSM cells. cAMP-PKA signaling is rapidly activated only in UtSM cells with E2 and inhibits ERK1/2 activation and proliferation. We therefore propose a model whereby E2's rapid activation of PKC alpha and cAMP-PKA signaling plays a central role in the maintenance of a low proliferative index in normal uterine smooth muscle via its inhibition of the MAPK cascade and these pathways are altered in leiomyomas to promote MAPK activation and proliferation. These studies demonstrate that rapid E2-signaling pathways contribute to the promotion of leiomyomas.

Concentration-dependent effects of a selective estrogen receptor modulator raloxifene on proliferation and apoptosis in human uterine leiomyoma cells cultured in vitro

BACKGROUND

This study was conducted to elucidate the effects of raloxifene on proliferation and apoptosis in cultured human uterine leiomyoma cells.

METHODS

The monolayer cultures were treated with graded concentrations (10(-9), 10(-8) and 10(-7) M) of raloxifene and 10(-7) M 17beta-estradiol (E(2)). Cell viability, percentage of proliferating cell nuclear antigen (PCNA)-positive cells, percentage of terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labelling (TUNEL)-positive cells and the expression of PCNA and Bcl-2 proteins were assessed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxylphenyl)-2-(4-sulphophenyl)-2H-tetraz olium assay, immunocytochemistry, TUNEL assay and western blot analysis, respectively.

RESULTS

Compared with untreated cultures, the number of viable cultured cells, percentage of PCNA-positive cells and PCNA protein expression were significantly decreased by treatment with 10(-9) M raloxifene, but increased by treatment with either 10(-8) M or 10(-7) M raloxifene. In contrast, the percentage of TUNEL-positive cells was significantly increased and Bcl-2 protein expression was significantly decreased by treatment with 10(-9) M raloxifene, whereas they were not affected by treatment with either 10(-8) or 10(-7) M raloxifene.

CONCLUSIONS

In cultured leiomyoma cells, low concentration (10(-9) M) of raloxifene may inhibit the growth of leiomyoma cells, whereas high concentrations (10(-8) M, 10(-7) M) of raloxifene may promote their growth.

A comparative study of the effect of raloxifene and gosereline on uterine leiomyoma volume changes and estrogen receptor, progesterone receptor, bcl-2 and p53 expression immunohistochemically in premenopausal women

OBJECTIVE

To compare the mechanism of action of raloxifene and gosereline induced shrinkage of leiomyomas via estrogen receptor, progesterone receptor, bcl-2 and p53 expression immunohistochemically.

STUDY DESIGN

Thirty-two premenopausal women affected by uterine leiomyomas were randomized into two equal groups. Group A was treated with gosereline (3.6 mg subcutaneous injection monthly) and group B was treated with raloxifene (60 mg daily per os) for 3 months before undergoing surgery. At entry and at the end of the treatment the leiomyoma volume was measured ultrasonografically and the volume change was calculated. Immunohistochemical detection of estrogen receptor (ER), progesterone receptor (PR), bcl-2 and p53 were performed on leiomyoma tissue samples from group A, group B and the matched-control group. H-scores for ER, PR, bcl-2 and p53 were calculated. The mean volume changes of leiomyomas and immunohistochemical H-score differences of ER, PR, bcl-2 and p53 were compared between groups.

RESULTS

The leiomyoma volume decreased significantly after treatment in gosereline group from baseline of 65 cm(3) to 35 cm(3), and in raloxifene group from 68 cm(3) to 50 cm(3), p<0.05. The difference between the before and after treatment leiomyoma volumes between the two treatments was not statistically significant. H-score of ER expression was significantly lower in gosereline group compared to control group (54.4 versus 113.2, p = 0.001), whereas H-score of PR expression was significantly lower with both gosereline and raloxifene groups compared to control group (64.8 for gosereline versus 94.6 for control, 73.6 for raloxifene versus 94.6 for control, p = 0.001). The bcl-2 expression was higher in both gosereline and raloxifene groups compared to control group (173.7 for gosereline versus 94.7 for control, 179.7 for raloxifene versus 94.7 for control, p = 0.001). The p53 expression was only lower with gosereline than the control group (169.4 versus 205.6, p = 0.001), whereas there was no significant change between the raloxifene group and the control group (201.9 versus 205.6) (p>0.05).

CONCLUSION

Raloxifene was as effective as gosereline in reducing leiomyoma volumes. Decreased PR expression may be a mechanism for tumor growth reduction in raloxifene treatment. In both treatment modalities, the mechanism of shrinkage of leiomyomas could not be increased apoptosis mediated by bcl-2 and p53 expression and should be investigated by further studies.

Ethnic distribution of estrogen receptor-alpha polymorphism is associated with a higher prevalence of uterine leiomyomas in black Americans

OBJECTIVE

To investigate whether polymorphisms in the estrogen receptor alpha (ERalpha) gene are associated with an increased risk of uterine leiomyomas (ULMs).

DESIGN

Genomic DNA was isolated from normal myometrium samples collected at the time of the hysterectomy.

SETTING

Volunteers in an academic research environment.

PATIENT(S)

One hundred ninety-eight women with surgically confirmed ULMs and 229 matched controls with nonfibroid uteri.

INTERVENTION(S)

Hysterectomy samples were collected from volunteers.

MAIN OUTCOME MEASURE(S)

The two PvuII and XbaI intronic polymorphisms in the ERalpha gene using polymerase chain reaction and restriction fragment length polymorphism.

RESULT(S)

The ERalpha PP genotype was associated with a significantly increased risk of ULM in black and white women, but not in Hispanic women. Women with the ERalpha PP genotype were 6.42 times (confidence limits 2.04-20.16) more likely to have ULMs than other genotypes. The ERalpha PP genotype was also significantly associated with larger tumor burden (>400 g). The overall prevalence of the PP genotype was significantly higher in black women (35%) than white (13%) or Hispanic (16%) women. Myometrial cell lines expressing the PP genotype exhibited enhanced proliferative response to estrogen in vitro compared with their pp counterparts.

CONCLUSION(S)

The ERalpha PP genotype is a genetic risk factor for ULM development among surgically treated women. The higher prevalence of this genotype in blacks might explain the increased occurrence of this tumor among black women.

Steroid Hormones and Leiomyomas

The sex steroid hormones play an important role in myoma maintenance and growth as evidenced by clinical, molecular, biological, and pharmacological models. It is hoped that the next phase of research will elucidate better the mechanisms through which these hormones modulate myoma growth and how they interact with the as yet unidentified other factors that play a role in myoma development and growth.

The effects of the selective estrogen receptor modulators, methyl-piperidino-pyrazole (MPP), and raloxifene in normal and cancerous endometrial cell lines and in the murine uterus

Since estrogens have vital functions in the uterus but might also contribute to endometrial cancer, we sought to determine the in vitro effects of methyl-piperidino-pyrazole (MPP), raloxifene, and beta-estradiol on Ishikawa and RL-95 endometrial cancer, and ovine luminal endometrial (oLE) cell lines and the in vivo effects of these compounds in the rodent uterus. MPP and raloxifene (1 nM) induced significant apoptosis in the endometrial cancer and oLE cell lines compared to beta-estradiol treated and control cells (P <or= 0.0001-0.001). To determine the in vivo uterine effects of these compounds, ovariectomized wild-type (WT) and estrogen receptor-beta knockout (ERbetaKO) mice were treated with 25, 50, 100, or 150 microg of each compound. Although raloxifene caused no significant increase in uterine weight, the presumptive ERalpha antagonist, MPP (25-150 microg) increased uterine weight, and cell proliferation significantly relative to vehicle control in WT and ERbetaKO mice (P <or= 0.001). However, MPP did not increase uterine wet weight as effectively as beta-estradiol (P <or= 0.0001), and administration of either 50 microg of MPP or raloxifene effectively reversed the positive effects of 50 and 100 microg beta-estradiol. Unexpectedly, in view of the in vitro studies, MPP and raloxifene treatment of ovariectomized mice did not induce apoptosis of the luminal epithelial cells but rather these compounds induced apoptosis of the underlying uterine stromal cells. These results demonstrate that MPP and raloxifene can exert apparently contrasting in vitro versus in vivo effects, and that they have mixed agonist/antagonist action on murine uterine ERalpha in vivo.

Antiproliferative and proapoptotic effects of raloxifene on uterine leiomyomas in postmenopausal women

OBJECTIVE

To study the cell effects of raloxifene on uterine and leiomyoma tissue in postmenopausal women.

DESIGN

Prospective, randomized, double-blind, placebo-controlled study.

SETTING

Department of Obstetrics and Gynecology, University "Magna Graecia" of Catanzaro, Italy.

PATIENT(S)

Forty postmenopausal women affected by uterine leiomyomas and selected for hysterectomy.

INTERVENTION(S)

Treatment for three cycles of 28 days with raloxifene at a dose of 180 mg/day orally (raloxifene group) or placebo tablets (3 tablets/day orally) (placebo group).

MAIN OUTCOME MEASURE(S)

Uterine and leiomyoma dimensions were measured in each subject at entry and before surgery. On leiomyomas and homologous myometrium the proliferating cell nuclear antigen (PCNA)-positive cells/total cells (PCNA/TC) and the Bcl-2-positive cells/Bax-positive cells (Bcl-2/Bax) ratios (%), as proliferation and apoptotic indexes, respectively, were measured.

RESULT(S)

After treatment, uterine and leiomyoma sizes were significantly changed in comparison with baseline and the placebo group. PCNA/TC and Bcl-2/Bax ratios were significantly higher in leiomyomas than in homologous myometrium. A significant difference was detected in PCNA/TC between the myometrium of the raloxifene and control groups, whereas no difference was observed in the Bcl-2/Bax ratio. A significant difference in PCNA/TC and Bcl-2/Bax ratios was detected in leiomyoma tissue between the raloxifene group and controls.

CONCLUSION(S)

In postmenopausal women, raloxifene administration reduces uterine leiomyomas by exerting a cell antiproliferative and proapoptotic action.

Gene therapy of uterine leiomyomas: adenovirus-mediated expression of dominant negative estrogen receptor inhibits tumor growth in nude mice

BACKGROUND

Leiomyomas (fibroids) are common estrogen-dependent uterine tumors with no effective medicinal treatment; hysterectomy is the mainstay of management.

STUDY DESIGN

This study was undertaken to investigate a potential therapy for leiomyoma; we used a mutated dominant-negative estrogen receptor gene delivered via an adenoviral vector (Ad-ER-DN).

RESULTS

Ad-ER-DN transduction, in both human and rat leiomyoma cell lines, induced an increase in both caspase-3 levels and BAX/Bcl-2 ratio with evident apoptosis in the TdT-mediated dUTP nick-end labeling assay. In nude mice, rat leiomyoma cells ex vivo transduced with Ad-ER-DN supported significantly smaller tumors compared with Ad-LacZ-treated cells 5 weeks after implantation. In mice treated by direct intratumor injection into preexisting lesions, Ad-ER-DN caused immediate overall arrest of tumor growth. The Ad-ER-DN-treated tumors demonstrated severely inhibited cell proliferation (BrdU index) and a marked increase in the number of apoptotic cells (TdT-mediated dUTP nick-end labeling index).

CONCLUSION

Dominant-negative estrogen receptor gene therapy may provide a nonsurgical treatment option for women with symptomatic uterine fibroids who want to preserve their uteri.

Contribution of phospholipase D in endothelin-1-mediated extracellular signal-regulated kinase activation and proliferation in rat uterine leiomyoma cells

Endothelin (ET)-1 is a mitogenic factor in numerous cell types, including rat myometrial cells. In the present study, we investigated the potential role of ET-1 in the proliferation of tumoral uterine smooth muscle cells (ELT-3 cells). We found that ET-1 exerted a more potent mitogenic effect in ELT-3 cells than in normal myometrial cells, as indicated by the increase in [3H]thymidine incorporation, cell number, and bromodeoxyuridine incorporation. The ET-1 was more efficient than platelet-derived growth factor and epidermal growth factor to stimulate proliferation. The ET-1-mediated cell proliferation was inhibited in the presence of U0126, a specific inhibitor of (mitogen-activated protein kinase ERK kinase), indicating that extracellular signal-regulated kinase (ERK) activation is involved. Additionally, ET-1 induced the activation of phospholipase (PL) D, leading to the synthesis of phosphatidic acid (PA). The ET-1-induced activation of PLD was twofold higher in ELT-3 cells compared to that in normal cells. The two cell types expressed mRNA for PLD1a and PLD2, whereas PLD1b was expressed only in ELT-3 cells. The exposure of cells to butan-1-ol reduced ET-1-mediated production of PA by PLD and partially inhibited ERK activation and DNA synthesis. Addition of exogenous PLD or PA in the medium reproduced the effect of ET-1 on ERK activation and cell proliferation. Collectively, these data indicate that ET-1 is a potent mitogenic factor in ELT-3 cells via a signaling pathway involving a PLD-dependent activation of ERK. This highlights the potential role of ET-1 in the development of uterine leiomyoma, and it reinforces the role of PLD in tumor growth.

Raloxifene prevents the growth of uterine leiomyomas in premenopausal women

OBJECTIVE

To evaluate the effects of raloxifene administration on uterine leiomyoma size in premenopausal women.

DESIGN

Prospective, randomized, open-label, controlled clinical trial.

SETTING

Tertiary care unit, University of Vienna, Austria.

PATIENT(S)

Twenty-five premenopausal women with uterine leiomyomas.

INTERVENTION(S)

Three months of treatment with raloxifene (180 mg/d) or no treatment.

MAIN OUTCOME MEASURE(S)

Baseline to end point percent change difference in leiomyoma volume between the therapy and control groups.

RESULT(S)

Raloxifene treatment prevented the progression of uterine leiomyomas. Compared with no medical intervention, raloxifene resulted in a decrease of myoma volume. Raloxifene was clinically well tolerated. No significant differences were detected in symptoms related to leiomyomas and hormonal status.

CONCLUSION(S)

In premenopausal women, high-dose raloxifene is well tolerated and inhibits the growth of leiomyomas.

Tissue microarray immunohistochemical expression of estrogen, progesterone, and androgen receptors in uterine leiomyomata and leiomyosarcoma

BACKGROUND

Benign uterine leiomyomata (LMA) are hormonally responsive neoplasms. To the authors' knowledge, little is known regarding the hormonal expression patterns of leiomyosarcomas (LMSs) of the uterus. The objective of the current study was to assess the immunohistochemical (IHC) patterns of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR) expression in LMA and LMS of the uterus using a tissue microarray. The authors also sought to assess the prognostic value of ER, PR, and AR expression in LMS.

METHODS

Between January 1991 and March 2001, 25 patients were identified with primary uterine LMS for whom tissue was available. A tissue microarray was created with 3 representative cores from each of the LMS cases, as well as from 19 cases with benign uterine LMA. IHC staining was scored as follows: negative (0-1) and positive (2-3). Outcome analyses were performed for LMS only. First recurrence was determined from the time of the initial diagnosis. Survival was determined from the time of the initial diagnosis to last follow-up.

RESULTS

ER, PR, and AR positivity in LMA compared with LMS was as follows: ER, 78% versus 40% (P = 0.03); PR, 88% versus 38% (P = 0.001); and AR, 32% versus 40% (P = 0.75). There was no difference noted with regard to IHC expression based on stage of LMS. The median overall survival for patients with LMS was 23.5 months (95% confidence interval, 19.5, NR). When adjusted for stage, PR and AR were found to be predictive of a lower risk of recurrence (P = 0.01 and P = 0.035, respectively). ER, PR, and AR were not found to be associated with overall survival after adjustment for stage. Tumor stage was found to be associated with survival (P = 0.005).

CONCLUSIONS

The rate of ER and PR expression was found to be significantly less in uterine LMS compared with LMA. ER, PR, and AR expression was observed in approximately 30-40% of uterine LMS cases. In the current series, PR and AR expression appeared to be associated with disease-free survival but were not found to correlate with overall survival.

Uterine leiomyoma in the Eker rat: A unique model for important diseases of women

Eker rats carry a defect in the Tsc-2 tumor suppressor gene and female Eker rats develop uterine leiomyoma with a high frequency. The presentation, response to hormones and molecular alterations in these mesenchymal smooth muscle tumors, closely resembles their cognate human disease. Female rats and tumor-derived cell lines from Eker rat leiomyomas (ELT lines) have been developed as an in vivo/in vitro model system for preclinical studies to identify novel therapeutic agents for this disease and for studying disease pathogenesis. In addition to serving as a model for uterine leiomyoma, Eker rats have proven valuable for studying lymphangioleiomyomatosis, a related proliferative smooth muscle disease of women.

Etiology and pathogenesis of uterine leiomyomas: a review

Uterine leiomyomas, or fibroids, represent a major public health problem. It is believed that these tumors develop in the majority of American women and become symptomatic in one-third of these women. They are the most frequent indication for hysterectomy in the United States. Although the initiator or initiators of fibroids are unknown, several predisposing factors have been identified, including age (late reproductive years), African-American ethnicity, nulliparity, and obesity. Nonrandom cytogenetic abnormalities have been found in about 40% of tumors examined. Estrogen and progesterone are recognized as promoters of tumor growth, and the potential role of environmental estrogens has only recently been explored. Growth factors with mitogenic activity, such as transforming growth factor- (subscript)3(/subscript), basic fibroblast growth factor, epidermal growth factor, and insulin-like growth factor-I, are elevated in fibroids and may be the effectors of estrogen and progesterone promotion. These data offer clues to the etiology and pathogenesis of this common condition, which we have analyzed and summarized in this review.

A randomized, placebo-controlled, dose-ranging trial comparing fulvestrant with goserelin in premenopausal patients with uterine fibroids awaiting hysterectomy

OBJECTIVE

To compare the use of a new antiestrogen fulvestrant with goserelin in reducing uterine fibroid growth before hysterectomy.

DESIGN

An international, multicenter, randomized, placebo-controlled study.

SETTING

Departments of obstetrics and gynecology.

PATIENT(S)

Premenopausal women (n = 307) diagnosed with uterine fibroids requiring hysterectomy.

INTERVENTION(S)

Over a 12-week period, patients received fulvestrant (50 mg, 125 mg, or 250 mg) as an i.m. injection, goserelin (3.6 mg) as a s.c. injection, or an injection-matched placebo once every 4 weeks. Patients underwent a hysterectomy at week 13.

MAIN OUTCOME MEASURES

Efficacy endpoints included changes in fibroid growth, endometrial thickness, and uterine volume. The excretion of urinary markers of bone resorption was also examined.

RESULT(S)

Goserelin significantly reduced fibroid growth and endometrial thickness compared with placebos. Fulvestrant did not significantly alter fibroid volume or endometrial thickness or change endpoints such as endometrial histology or vaginal bleeding. Fulvestrant was associated with fewer postmenopause-related adverse events than goserelin. Goserelin, but not fulvestrant, significantly increased markers of bone resorption.

CONCLUSION(S)

At doses equivalent to those used for the treatment of breast cancer in postmenopausal women, fulvestrant did not significantly inhibit fibroid growth and, of particular note, did not lead to bone resorption.

Myometrial effects of selective estrogen receptor modulators on estradiol-responsive gene expression are gene and cell-specific

We examined in vivo effects of selective estrogen receptor modulators (SERMs) 4-OH-tamoxifen (Tam), GW 5638 (GW) and EM-800 (EM) on myometrial gene expression. The uteri of ovariectomized ewes were infused with 10(-7)M of one SERM via indwelling catheters for 24h preceding hysterectomy. Half of the ewes in each SERM group received an intramuscular injection of 50 microg 17beta-estradiol (E2) 18 h prior to hysterectomy. Northern blot analysis and in situ hybridization demonstrated that E2 increased estrogen receptor (ER), progesterone receptor (PR) and cyclophilin (CYC) gene expression in the cells of both inner layer of myometrium (IM) and outer layer of myometrium (OM) as well as glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene expression in OM. Tam also increased ER mRNA levels in OM. EM appeared to increase ER gene expression, but antagonized E2's up-regulation of PR and CYC gene expression in both IM and OM. Tam and GW also antagonized E2 up-regulation of PR gene expression in OM but not IM. No SERM affected GAPDH gene expression with or without E2. Immunohistochemistry indicated that E2 increased nuclear ER and PR protein levels in both IM and OM. EM was unique in up-regulating ER protein levels, opposite to its effects in endometrial cells. All SERMs tested antagonized this increase in PR immunostaining preferentially in OM compared to the IM layer. These results illustrate gene and cell layer-specific effects of SERMs in sheep myometrium.

Transdominant suppression of estrogen receptor signaling by progesterone receptor ligands in uterine leiomyoma cells

Uterine leiomyomas develop in reproductive-age women with high frequency and are dependent on the production of ovarian hormones. While it is generally accepted that these tumors are estrogen (E(2))-responsive, the role of progesterone (P(4)) in modulating tumor growth is less clear. In the present study, an in vivo/in vitro rat model was used to characterize progesterone receptor (PR) isoform expression in uterine leiomyoma and investigate PR signaling using progestins and antiprogestins in the leiomyoma-derived cell line ELT-3. PR-A was the predominant isoform expressed in normal myometrium, leiomyomas and ELT3 cells. In the normal myometrium, PR-A and PR-B levels varied during the estrous cycle with low ratios of PR-A relative to PR-B (PR-A/PR-B) coinciding with times of cell proliferation. Although PR ligands had no effect on basal levels of uterine leiomyoma cell proliferation in vitro, both progestins and antiprogestins inhibited E(2)-stimulated cell proliferation. In addition, E(2)-stimulated transactivation of an estrogen-response-element reporter gene as well as E(2)-induced upregulation of the PR were also inhibited by PR ligands. These data indicate that PR ligands can transdominantly suppress estrogen receptor signaling and stimulation of uterine leiomyoma cell growth.

Protective effect of pregnancy for development of uterine leiomyoma

Many factors that can modulate the risk of developing uterine leiomyoma have been identified, including parity. Epidemiological data on decreased risk of developing this disease has been subject to different interpretations regarding whether pregnancy per se is protective or, as leiomyomas are a major cause of infertility, women that develop these tumors are less fertile and thus have lower pregnancy rates. We have utilized an animal model genetically predisposed to uterine leiomyoma to investigate the potential protective effect of pregnancy on the risk of developing this disease. Female Eker rats that carry a mutation in the tuberous sclerosis 2 (Tsc-2) tumor suppressor gene develop uterine leiomyoma with a frequency of 65% when nulliparous. These animals were bred with intact or vasectomized males and tumor incidence determined after a single pregnancy (to confirm fertility) or multiple pregnancies over the lifetime of the animals. Females with multiple litters displayed a dramatic shift in tumor incidence and presentation. Tumor incidence decreased from 71% in single litter females to 10% in females that had multiple litters (average: five litters/animal). Interestingly, females bred with vasectomized males also exhibited a reduced tumor incidence of 41%, suggesting that the hormonal changes associated with early stages of pregnancy that occur in pseudopregnant females may have contributed to the protective effect of pregnancy.

Cardiovascular effects of raloxifene hydrochloride

Raloxifene hydrochloride binds to the estrogen receptor and shows tissue-selective effects; thus, it belongs to a class of drugs recently described as selective estrogen receptor modulators (SERMs). Tissue selectivity of raloxifene may be achieved through several mechanisms: the ligand structure, interaction of the ligand with different receptor subtypes in various tissues, and intracellular events after ligand binding. Raloxifene has estrogen-agonist effects on bone and lipids and estrogen antagonist effects on the breast and uterus. In addition to its well established effects on osteoporosis, recent preclinical and clinical findings suggest that raloxifene also possesses beneficial effects on the cardiovascular system. These findings indicated that raloxifene may have cardioprotective properties without an increased risk of cancer or other side effects. Raloxifene has been shown to reduce total and low-density lipoprotein cholesterol concentrations in plasma, an effect similar to that produced by estrogens. Unlike estrogens, however, raloxifene does not increase high-density lipoprotein cholesterol and triglyceride levels in plasma. Endothelium is thought to play an important role in the genesis of atherosclerosis. Several lines of evidence suggest that an intervention with endothelial function might influence the progression of coronary disease and the incidence of cardiovascular events. Raloxifene increases the nitric oxide/endothelin-1 ratio, and improves endothelium-dependent vasomotion in post-menopausal women to the same extent as estrogens. Furthermore, in two randomized trials on post-menopausal women raloxifene reduced homocysteine levels, another independent risk factor for the development of cardiovascular disease. Although estrogens remain the drugs of choice in the hormonal therapy of most postmenopausal women, raloxifene may represent and alternative in women who are at risk of coronary artery disease.

Effects of raloxifene treatment on uterine leiomyomas in postmenopausal women

OBJECTIVE

To evaluate the effects of raloxifene administration on uterine and uterine leiomyoma sizes in postmenopausal women.

DESIGN

Prospective randomized, double-blind, placebo-controlled clinical trial.

SETTING

Department of Gynecology, Obstetrics, and Pathophysiology of Human Reproduction, University of Naples "Federico II", Italy.

PATIENT(S)

Seventy spontaneous postmenopausal women affected by uterine leiomyomas.

INTERVENTION(S)

Twelve cycles (of 28 days each) of treatment with raloxifene (60 mg daily per os) or placebo.

MAIN OUTCOME MEASURE(S)

At entry and at every 3 cycles, uterine and uterine leiomyoma dimensions were measured by means of transvaginal ultrasound. The difference between uterine and leiomyoma volumes (Delta size) was calculated in all subjects. The characteristics of uterine bleeding and the side effects of the treatments were assessed using a daily diary.

RESULT(S)

After 6, 9, and 12 cycles of therapy, in subjects treated with raloxifene, the mean uterine and uterine leiomyoma size were significantly decreased, and the mean Delta size significantly increased in comparison with basal values and the placebo group. No significant differences in uterine bleeding were detected between the two groups.

CONCLUSION(S)

In postmenopausal women raloxifene appears to act selectively on uterine leiomyomas, reducing their size.

The role of tamoxifen in the treatment of symptomatic uterine leiomyomata -- a pilot study

OBJECTIVES

To determine the efficacy of tamoxifen in patients with leiomyomata complaining of abdominal pains and vaginal bleeding.

STUDY DESIGN

Prospective, randomized, double blind study. A total of 10 patients received for 6 months 20 mg tamoxifen daily, and 10 women received placebo. All patients underwent serial pelvic and ultrasound exams and endometrial sampling was performed prior to initiation of treatment. After 5 years, the patients were interviewed again.

RESULTS

Uterine size was not affected by the use of tamoxifen. Patients reported a blood loss decrease of 40--50% at the end of the study (P=0.0001). In the control group a slight increase in blood loss was reported. Hemoglobin levels remained unchanged in both groups. In the study group patients reported after 4 months of treatment a substantial decrease in the intensity of pain (P=0.018). Seven patients in the study group and one patient in the control group developed ovarian cysts.

CONCLUSIONS

Treatment with tamoxifen added only marginal benefit while causing unacceptable side effects. Tamoxifen does not seem to be a useful adjunct in the treatment of symptomatic uterine leiomyomata and its use for this indication should be discouraged.

Selective estrogen receptor modulators: the ideal estrogen replacement?(2)(2)

The ultimate estrogen for replacement therapy should exert beneficial actions upon the skeletal, cardiovascular, and central nervous systems while displaying minimal side effects in the uterus and breast. Selective estrogen receptor modulators (SERMs), such as tamoxifen and raloxifene, have recently been studied to achieve these aims. Not only are these agents potentially effective in reducing a patient's risk of breast carcinoma but they have also been shown to increase bone mineral density and prevent osteoporosis. Displaying favorable effects on lipid metabolism, SERMs also may be protective against coronary heart disease and myocardial infarction. Tamoxifen's adverse side effects on the uterus have not been noted with raloxifene, because the latter behaves as an estrogen antagonist in the endometrium. Ongoing studies, such as the Study of Tamoxifen and Raloxifene and the Raloxifene Use for the Heart trials, may help to further determine whether SERMs are the ideal estrogen for the postmenopausal female patient.

Uterine leiomyomas: mechanisms of tumorigenesis

Uterine leiomyomas, also called fibroids, are the most common reproductive tract neoplasm and the leading indication for hysterectomy in premenopausal women. The discovery and development of medicinal therapies for uterine leiomyoma have been hampered by a lack of understanding regarding the etiology and molecular mechanisms underlying the development of these lesions. Although the estrogen responsiveness of uterine leiomyoma is well established, the impact of environmental estrogens and their contribution to the development of these tumors is currently unknown. The Eker rat model of uterine leiomyoma has proven useful for addressing these issues and understanding the pathophysiology of this disease. The Eker rat is the only animal model that develops spontaneous uterine leiomyomas, and these tumors share many characteristics with those found in humans. The availability of tumor-derived cell lines from these rats has made this a valuable in vitro/in vivo model system for experimental studies to investigate molecular mechanisms of disease and to design interventional and preventative strategies for this clinically relevant tumor.

Selective estrogen receptor modulators in reproductive medicine and biology

Estrogen replacement therapy has significant potential benefits for postmenopausal women, such as improvement of menopausal symptoms and protection from osteoporosis, but it may also increase a woman's risk of breast cancer. Also, some women do not take hormone replacement therapy because of such undesirable side effects as breast tenderness and uterine bleeding. Therefore, there is much interest in the development of compounds that provide the benefits of estrogen replacement therapy without the risks and side effects. The selective estrogen receptor modulators make up one class of compounds with both estrogen agonist and antagonist activity. This review discusses the clinical indications, risks, benefits, and mechanisms of action of selective estrogen receptor modulators and related compounds.

[Effect of selective estrogen receptor modulators on estrogen-sensitive tissues]

Selective estrogen receptor modulators (SERMs) act exclusively through estrogen receptors and possess tissue-specific agonistic or antagonistic properties. The effects of all referred SERMs in bone and cardiovascular system are estrogenic, namely they inhibit postmenopausal bone loss and favorably influence plasma lipoproteins and some coagulation factors. The aim of this paper is to review the effects of SERMs on estrogen-dependent breast tissues and on the endometrium. There are two types of SERMs in clinical use, based on their chemical structure: the triphenylethylenes and the benzothiophenes. The prototype of the SERMs with triphenylethylene structure is tamoxifen. Tamoxifen, like all other SERMs, is an estrogen antagonist in the breast and is widely used for adjuvant treatment of breast cancer. A recent study suggests that tamoxifen also may prevent breast cancer in patients at risk. Because of the partial estrogenic activity of tamoxifen in the endometrium, its clinical use is associated with uterine hypertrophy and an increased risk of endometrial cancer. Other triphenylethylene SERMs, droloxifene, toremifene, and idoxifene, also show efficacy in the treatment of breast cancer, in a manner similar to tamoxifen. A better toxicology profile and a decreased endometrial estrogen agonism may be advantages of the new triphenylethylene SERMs. Raloxifene is a SERM with a chemical structure different from triphenylethylenes. Raloxifene, a benzothiophene, possesses an estrogen-antagonistic effect in the breast similar to triphenylethylenes. Clinical studies on postmenopausal osteoporotic women on raloxifene as compared with placebo show a significant decrease in the rate of newly diagnosed breast cancers. In clinical studies, in contrast to tamoxifen, no stimulatory effect in the endometrium could be observed with raloxifene.

Caprine genital leiomyosarcoma

An aged Saanen doe was euthanized following repeated severe hemorrhage from the vulva. Necropsy examination revealed mural thickening of tubular genitalia with firm, protruding intralumenal masses containing blood-filled cavitations, and effacement of normal cervical architecture. Histologically, uterine and cervical masses comprised a variably dense population of mildly pleomorphic spindle cells forming interlacing streams supported by variably dense collagenous stroma. Immunoperoxidase staining of neoplastic cells was positive for muscle-specific actin, supporting the diagnosis of low-grade leiomyosarcoma. Months later, the doe's twin was likewise euthanized due to persistent bleeding from the vulva associated with a large vulvar mass having histopathologic features similar to those of the previous case. The clinical, gross, and histologic findings are similar to five cases of caprine genital leiomyosarcoma identified in retrospectively analyzed case material. Analysis of caprine tumor accessions over 20 years demonstrated a significantly higher incidence of genital leiomyosarcoma within the Saanen breed.

Modern antioestrogens and the coming revolution in women's health care

This review will focus on antioestrogens and selective oestrogen receptor modulators (SERMS). The more traditional SERMS, clomiphene citrate and tamoxifen, will be reviewed along with such modern drugs as raloxifene and faslodex, with emphasis upon their actions on breast, uterus, bone and lipids. The future potential of these medications, in the management of oestrogen-dependent gynaecological conditions such as endometriosis, dysfunctional uterine bleeding, fibroids and breast cancer will be discussed.

Hormone replacement therapy in women treated for gynaecological malignancy

Can we prescribe hormone replacement therapy (HRT) safely for women, with postmenopausal complaints who were treated for a gynaecological malignancy? Only three retrospective studies have investigated this issue in endometrial cancer patients. No recurrences or deaths occurred in these treated groups. However, the physician introduced bias through the selection of favourable groups. At present, combined estrogen and progestogen therapy is probably not contra-indicated in endometrial cancer stage I and probably also not in stage II, although so far there is only circumstantial evidence. Squamous cell cancers of the cervix, vulva, and vagina are unlikely to be influenced by HRT. In the only study available of women with ovarian cancer, < or = 50 years, estrogen replacement therapy did not have a negative influence on (disease-free) survival. According to the data currently available, no evidence exists that HRT adversely influences survival and overall survival after treatment for ovarian cancer. In general, adenocarcinomas of the cervix and leiomyosarcomas of the uterus may be managed such as the adenocarcinomas of the uterus. During the last 25 years, HRT has been shown to substantially reduce the risk of cardiovascular diseases, osteoporotic fractures and colon carcinoma. On the other hand there is a significant increase of the risk in breast cancer with prolonged use of > 5 years. Re-evaluation of the current view that HRT should no be given to women treated for a gynaecological malignancy is strongly warranted after evaluating the advantages and the disadvantages of HRT use in each individual patient. Long-term HRT in women treated for a gynaecological cancer must be based on the medical history of the individual patient (and her family).

Selective estrogen receptor modulators: Women's panacea for the next millennium?

The purpose of this review is to assimilate relevant experimental and clinical information available on selective estrogen receptor modulators with respect to their potential use as agents to improve women's health in the postmenopausal years. In addition, the mechanisms of action of these drugs are outlined. Selective estrogen receptor modulators represent an exciting group of antiestrogens that possess agonist action on bone, lipids, and lipoproteins and antagonistic action in the endometrium and breast. Thus in theory these drugs may preserve bone density and reduce the risk of osteoporotic fracture and coronary heart disease at the same time that they lower the incidences of breast and endometrial neoplasms. Short-term data with the use of raloxifene suggest that bone is preserved and lipid profiles are less atherogenic. Long-term studies are needed to determine whether raloxifene or other selective estrogen receptor modulators are associated with any decrease in the risk of breast or endometrial cancer.

Other medical management of uterine fibroids

Several medicines are emerging with the potential to treat symptomatic uterine fibroids. Anti-progesterone compounds seem particularly promising. These drugs have been widely used for nearly 20 years and are known to be safe; medical politics have prevented their proper investigation for uterine fibroids. In particular, the value of mifepristone, 50 mg per day for 3 months, seems particularly promising. Further investigation is clearly warranted for this medicine. Several anti-oestrogen compounds have recently become available and may also be useful for the medical treatment of symptomatic uterine fibroids. This includes the possibility of the use of selective oestrogen receptor modulators as well as the prospect of the use of pure anti-oestrogens. On a longer time frame, inhibitors of angiogenesis may be useful. These medicines would act upon the blood supply to uterine fibroids. Physicians also have an obligation to investigate scientifically any promising naturopathic treatment that appears to have possible activity for symptomatic fibroids.

The selective estrogen receptor modulator, raloxifene: an overview of nonclinical pharmacology and reproductive and developmental testing

Raloxifene is a nonsteroidal, selective estrogen receptor modulator being developed by Eli Lilly and Company as a therapeutic agent for postmenopausal osteoporosis. In the ovariectomized (OVX) rat, raloxifene prevents the loss of bone at the distal metaphysis of the femur, proximal tibia, and vertebrae; reduces cancellous bone resorption; and reduces serum cholesterol, but does not cause any significant changes in stromal eosinophilia or uterine epithelium. In estrogen-stimulated OVX rats, raloxifene prevents the morning lowering of serum luteinizing hormone levels, produces a reduction in afternoon serum prolactin levels, antagonizes pituitary weight increase, and antagonizes stimulation of mammary gland development. Raloxifene also has been shown to exhibit antiestrogenic activity in several in vivo and in vitro mammary tumor models. Raloxifene treatment results in regression of endometriosis in both a surgically prepared, rat uterine explant model and in Rhesus macaques diagnosed with spontaneous endometriosis before exposure. Also, uterine leiomyomas in estrogen-stimulated OVX guinea pigs regress after the onset of raloxifene treatment. Raloxifene antagonizes testosterone-induced increases in prostate weight of castrated rats, but does not bind to androgen receptors or affect prostatic 5-alpha-reductase or testicular steroid 17-alpha-hydroxylase activity. A series of preclinical toxicology studies was designed to characterize reproductive and developmental outcomes following various schedules of raloxifene treatment in rats or rabbits. Studies of female reproduction and developmental outcome were conducted primarily at pharmacologic doses (0.1, 1, or 10 mg/kg/d); male reproductive studies used higher doses (10, 30, or 100 mg/kg/d). In this series of studies, male reproductive end points were not affected, whereas embryo implantation, fetal rabbit morphology, and several aspects of offspring development were disrupted by the lowest dose of maternal raloxifene treatment, a profile consistent with estrogen antagonist activity.