Bazedoxifene analogs as potential WDHD1 degraders and antitumor agents: Synthesis, evaluation and molecular dynamics simulation studies.

DNA repair is strongly associated with tumor resistance to radiotherapy and chemotherapy. WD repeat and HMG-box DNA binding protein 1 (WDHD1) is a key adaptor for homologous recombination repair of DNA, and its overexpression is relevant to the poor prognosis of many tumor patients. We previously have identified and validated bazedoxifene (BZA), which had 60% inhibitory rate on WDHD1 in MCF7 cells at 10 µM, from the Food and Drug Administration-approved compound library. Here, we initially established the binding model of BZA, synthesized and evaluated eight BZA analogs. Further, we detailed the use of molecular dynamics simulations to provide insights into the basis for activity against WDHD1. This binding mode will be instructive for the development of new WDHD1 degraders.

Benzimidazole compound abrogates SARS-COV-2 receptor-binding domain (RBD)/ACE2 interaction In vitro.

The development of clinically actionable pharmaceuticals against coronavirus disease (COVID-19); an infectious disease caused by the SARS-CoV-2 virus is very important for ending the pandemic. Coronavirus spike glycoprotein (GP)-Receptor Binding Domain (RBD) and its interaction with host receptor angiotensin converting enzyme 2 (ACE2) is one of the most structurally understood but therapeutically untapped aspect of COVID-19 pathogenesis. Binding interface based on previous x-ray structure of RBD/ACE2 were virtually screened to identify fragments with high-binding score from 12,000 chemical building blocks. The hit compound was subjected to fingerprint-based similarity search to identify compounds within the FDA-approved drug library containing the same core scaffold. Identified compounds were then re-docked into of RBD/ACE2. The best ranked compound was validated for RBD/ACE2 inhibition using commercial kit. Molecular dynamics simulation was conducted to provide further insight into the mechanism of inhibition. From the original 12000 chemical building blocks, benzimidazole (BAZ) scaffold was identified. Fingerprint-based similarity search of the FDA-approved drug library for BAZ-containing compounds identified 12 drugs with the benzimidazole-like substructure. When these compounds were re-docked into GP/ACE2 interface, the consensus docking identified bazedoxifene as the hit. In vitro RBD/ACE2 inhibition kinetics showed micromolar IC50 value (1.237 µM) in the presence of bazedoxifene. Molecular dynamics simulation of RBD/ACE2 in the presence BAZ resulted in loss of contact and specific hydrogen-bond interaction required for RBD/ACE2 stability. Taken together, these findings identified benzimidazole scaffold as a building block for developing novel RBD/ACE2 complex inhibitor and provided mechanistic basis for the use of bazedoxifene as a repurposable drug for the treatment of COVID-19 acting at RBD/ACE2 interface.

Repurposing of drugs as STAT3 inhibitors for cancer therapy.

Drug repurposing is a valuable approach in delivering new cancer therapeutics rapidly into the clinic. Existing safety and patient tolerability data for drugs already in clinical use represent an untapped resource in terms of identifying therapeutic agents for off-label protein targets. The multicellular effects of STAT3 mediated by a range of various upstream signaling pathways make it an attractive therapeutic target with utility in a range of diseases including cancer, and has led to the development of a variety of STAT3 inhibitors. Moreover, heightened STAT3 transcriptional activation in tumor cells and within the cells of the tumor microenvironment contribute to disease progression. Consequently, there are many STAT3 inhibitors in preclinical development or under evaluation in clinical trials for their therapeutic efficacy predominantly in inflammatory diseases and cancer. Despite these advances, many challenges remain in ultimately providing STAT3 inhibitors to patients as cancer treatments, highlighting the need not only for a better understanding of the mechanisms associated with STAT3 activation, but also how various pharmaceutical agents suppress STAT3 activity in various cancers. In this review we discuss the importance of STAT3-dependent functions in cancer, review the status of compounds designed as direct-acting STAT3 inhibitors, and describe some of the strategies for repurposing of drugs as STAT3 inhibitors for cancer therapy.

Antiviral efficacy of selective estrogen receptor modulators against SARS-CoV-2 infection in vitro and in vivo reveals bazedoxifene acetate as an entry inhibitor.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the seventh member of the coronavirus family that can infect humans. Recently, more contagious and pathogenic variants of SARS-CoV-2 have been continuously emerging. Clinical candidates with high efficacy and ready availability are still in urgent need. To identify potent anti-SARS-CoV-2 repurposing drugs, we evaluated the antiviral efficacy of 18 selective estrogen receptor modulators (SERMs) against SARS-CoV-2 infection. Six SERMs exhibited excellent anti-SARS-CoV-2 effects in Vero E6 cells and three human cell lines. Clomifene citrate, tamoxifen, toremifene citrate, and bazedoxifene acetate reduced the weight loss of hamsters challenged with SARS-CoV-2, and reduced hamster pulmonary viral load and interleukin-6 expression when assayed at 4 days postinfection. In particular, bazedoxifene acetate was identified to act on the penetration stage of the postattachment step via altering cholesterol distribution and endosome acidification. And, bazedoxifene acetate inhibited pseudoviruses infection of original SARS-CoV-2, Delta variant, Omicron variant, and SARS-CoV. These results offer critical information supporting bazedoxifene acetate as a promising agent against coronaviruses.

Bazedoxifene plus conjugated estrogens improve menopausal symptoms in postmenopausal women: a systematic review and meta-analysis.

Our aim is to evaluate the efficacy of bazedoxifene (BZA) plus conjugated estrogens (CE) on menopausal symptoms in postmenopausal women. A series of databases including PubMed, EMBASE, Medline, Web of science, China national knowledge internet and Wanfang database up to 31 October 2021 were searched, and randomized controlled trials (RCTs) of BZA/CE for menopausal symptoms were included. Seven RCTs involving 5431 patients were included in this study. Compared with placebo group, there were significantly reduce in daily number of hot flushes, daily number of moderate or severe hot flushes, the percentages of parabasal cells and the time to fall sleep when patients treated with BZA/CE. Besides, there were significant improvement in sleep disturbance and total MENQOL. However, no significant improvements in sleep adequacy were observed in the three groups. Furthermore, BZA 20 mg/CE 0.625 mg was more effective than BZA 20 mg/CE 0.45 mg in improving the menopausal symptoms. Therefore, both bazedoxifene 20 mg plus conjugated estrogens 0.45 mg and bazedoxifene 20 mg plus conjugated estrogens 0.625 mg could significantly improve the menopause-related symptoms and MENQOL in postmenopausal women, and the curative effects of BZA 20 mg/CE 0.625 mg were better than that of BZA 20 mg/CE 0.45 mg. These findings need to be further confirmed by more high-quality RCTs.

Bazedoxifene increases the proliferation of human arterial endothelial cells but does not affect the expression of cyclins A, B, and D1 and of p27Kip1.

OBJECTIVE: Endothelial dysfunction and denudation are considered a first step in atherosclerosis. Endothelial proliferation is key for cellular repair. The effect of bazedoxifene on the vascular endothelium has not been explored. We investigated the effect of bazedoxifene on endothelial cell proliferation. METHODS: Primary cultures from human umbilical artery endothelial cells were used in dose-response experiments (0.1, 1.0, and 10.0 EC50 dose) with bazedoxifene, estradiol, raloxifene and a combination of bazedoxifene and estradiol. Proliferation was assessed with the XTT colorimetric cell-proliferation assay. The possible participation of cyclins A, B, D1 and p27Kip1 was analyzed by the measurement of their expression at both the protein and the gene levels. RESULTS: A significant increase of similar size for cell proliferation was obtained with bazedoxifene, estradiol and raloxifene, but no significant change was observed for the association of bazedoxifene and estradiol. The impact was detected at the first 0.1 EC50 dose and was not dose-dependent. Estradiol achieved a significant increase in the protein expression of cyclin A and p27Kip1, but no change was detected for the other compounds at either the gene or protein level. CONCLUSION: Bazedoxifene demonstrated a proliferative effect of similar size to estradiol in cultured human umbilical artery endothelial cells. The molecular mechanisms need further investigation.

Bazedoxifene, a GP130 Inhibitor, Modulates EMT Signaling and Exhibits Antitumor Effects in HPV-Positive Cervical Cancer.

Persistent HPV (Human Papillomavirus) infection is the primary cause of cervical cancer. Despite the development of the HPV vaccine to prevent infections, cervical cancer is still a fatal malignant tumor and metastatic disease, and it is often difficult to treat, so a new treatment strategy is needed. The FDA-approved drug Bazedoxifene is a novel inhibitor of protein-protein interactions between IL-6 and GP130. Multiple ligand simultaneous docking and drug repositioning approaches have demonstrated that an IL-6/GP130 inhibitor can act as a selective estrogen modulator. However, the molecular basis for GP130 activation in cervical cancer remains unclear. In this study, we investigated the anticancer properties of Bazedoxifene in HPV-positive cervical cancer cells. In vitro and in vivo experiments showed that Bazedoxifene inhibited cell invasion, migration, colony formation, and tumor growth in cervical cancer cells. We also confirmed that Bazedoxifene inhibits the GP130/STAT3 pathway and suppresses the EMT (Epithelial-mesenchymal transition) sub-signal. Thus, these data not only suggest a molecular mechanism by which the GP130/STAT3 pathway may promote cancer, but also may provide a basis for cervical cancer replacement therapy.

Bazedoxifene, a Selective Estrogen Receptor Modulator, Promotes Functional Recovery in a Spinal Cord Injury Rat Model.

In research on various central nervous system injuries, bazedoxifene acetate (BZA) has shown two main effects: neuroprotection by suppressing the inflammatory response and remyelination by enhancing oligodendrocyte precursor cell differentiation and oligodendrocyte proliferation. We examined the effects of BZA in a rat spinal cord injury (SCI) model. Anti-inflammatory and anti-apoptotic effects were investigated in RAW 264.7 cells, and blood-spinal cord barrier (BSCB) permeability and angiogenesis were evaluated in a human brain endothelial cell line (hCMEC/D3). In vivo experiments were carried out on female Sprague Dawley rats subjected to moderate static compression SCI. The rats were intraperitoneally injected with either vehicle or BZA (1mg/kg pre-SCI and 3 mg/kg for 7 days post-SCI) daily. BZA decreased the lipopolysaccharide-induced production of proinflammatory cytokines and nitric oxide in RAW 264.7 cells and preserved BSCB disruption in hCMEC/D3 cells. In the rats, BZA reduced caspase-3 activity at 1 day post-injury (dpi) and suppressed phosphorylation of MAPK (p38 and ERK) at dpi 2, hence reducing the expression of IL-6, a proinflammatory cytokine. BZA also led to remyelination at dpi 20. BZA contributed to improvements in locomotor recovery after compressive SCI. This evidence suggests that BZA may have therapeutic potential to promote neuroprotection, remyelination, and functional outcomes following SCI.

Inhibition of Interleukin-6/glycoprotein 130 signalling by Bazedoxifene ameliorates cardiac remodelling in pressure overload mice.

The role of IL-6 signalling in hypertensive heart disease and its sequelae is controversial. Our group demonstrated that Bazedoxifene suppressed IL-6/gp130 signalling in cancer cells but its effect on myocardial pathology induced by pressure overload is still unknown. We explored whether Bazedoxifene could confer benefits in wild-type C57BL/6J mice suffering from transverse aortic constriction (TAC) and the potential mechanisms in H9c2 myoblasts. Mice were randomized into three groups (Sham, TAC, TAC+Bazedoxifene, n = 10). Morphological and histological observations suggested TAC aggravated myocardial remodelling while long-term intake of Bazedoxifene (5 mg/kg, intragastric) attenuated pressure overload-induced pathology. Echocardiographic results indicated Bazedoxifene rescued cardiac function in part. We found Bazedoxifene decreased the mRNA expression of IL-6, MMP2, Col1A1, Col3A1 and periostin in murine hearts after 8-week surgery. By Western blot detection, we found Bazedoxifene exhibited an inhibition of STAT3 activation in mice three hours and 8 weeks after TAC. Acute TAC stress (3 hours) led to down-regulated ratio of LC3-Ⅱ/LC3-Ⅰ, while in mice after long-term (8 weeks) TAC this ratio becomes higher than that in Sham mice. Bazedoxifene inverted the autophagic alteration induced by TAC at both two time-points. In H9c2 myoblasts, Bazedoxifene suppressed the IL-6-induced STAT3 activation. Moreover, IL-6 reduced the ratio of LC3-Ⅱ/LC3-Ⅰ, promoted P62 expression but Bazedoxifene reversed both changes in H9c2 cells. Our data suggested Bazedoxifene inhibited IL-6/gp130 signalling and protected against cardiac remodelling together with function deterioration in TAC mice.

Bazedoxifene improves renal function and increases renal phosphate excretion in patients with postmenopausal osteoporosis.

INTRODUCTION: Because aging is a predictor of renal insufficiency in the general population, renal function is a concern in postmenopausal patients undergoing treatment for osteoporosis. Although high serum phosphate concentration is a predictor of renal insufficiency, the effect of selective estrogen receptor modulator (SERM) on renal function and phosphate homeostasis remains to be established. MATERIALS AND METHODS: We administered 20 mg/day bazedoxifene to 48 postmenopausal osteoporotic women who had been taking alfacalcidol for ≥ 6 months, and assessed lumbar spine bone mineral density (LS-BMD), renal function (by calculating estimated glomerular filtration rate using serum cystatin-C levels [eGFRcys] [range 38.0-98.2 mL/min/1.73 m2]), and phosphate homeostasis. RESULTS: LS-BMD was significantly higher 6 months after the initiation of bazedoxifene administration. eGFRcys had increased by 3 months after initiation and was stable until 12 months. Serum phosphate gradually decreased after initiation, reaching statistical significance at 6 months. The changes in serum phosphate were also significant when the maximum tubular reabsorption rate of phosphate was normalized to glomerular filtration rate (TmP/GFR), indicating that bazedoxifene treatment reduces serum phosphate by increasing the urinary excretion of phosphate. The change in eGFRcys after the initiation of bazedoxifene was significantly negatively correlated with the change in serum phosphate, suggesting that a reduction in serum phosphate improves renal function. CONCLUSION: Bazedoxifene improves renal function, possibly by increasing renal phosphate excretion, in postmenopausal osteoporotic women without severe renal insufficiency.

Bazedoxifene effects on osteoprotegerin, insulin-like growth factor, tumor necrosis factor and bone mineral density.

To observe the clinical effect of estrogenic drugs (Bazedoxifene) on bone targeting in the treatment of osteoporosis and explore its mechanism. METHODS: 112 patients with postmenopausal osteoporosis who received Bazedoxifene drugs in our hospital from January to December 2018 were collected as a study group, and 56 patients treated with calcium alone were collected as a control group. the risk of adverse events such as bone mineral density, osteoprotegerin (OPG), insulin-like growth factor (IGF), tumor necrosis factor (TNF-α), and fracture after treatment were analyzed before and after treatment. RESULTS: There was no significant difference in the mean lumbar positive position (L2-4) and right femoral neck bone density and OPG, IGF, TNF-α level between the two groups before treatment (P>0.05). The total effective rate of clinical treatment in the study group was 88.39%, the control group was 23.21%, the difference between the two groups was statistically significant (P˂0.05). After treatment, the mean lumbar positive position (L2-4) and the right femoral neck bone density and OPG, IGF in the study group were higher than those in the control group, lower than those in the control group (P<0.05). the occurrence of adverse events such as fracture, spinal deformation and fatigue in the study group after 12 months of treatment was significantly lower than that in the control group (P<0.05), but there was no significant difference in the occurrence of hot flashes and venous thromboembolism between the two groups (P>0.05). CONCLUSION: Bazedoxifene is an effective drug for the treatment of postmenopausal osteoporosis. It can not only prevent the rapid loss of bone mass, effectively relieve the symptoms of menopause, but also improve bone density and reduce the risk of fracture.

Bazedoxifene exhibits growth suppressive activity by targeting interleukin-6/glycoprotein 130/signal transducer and activator of transcription 3 signaling in hepatocellular carcinoma.

The interleukin (IL)-6/glycoprotein (GP)130/signal transducer and activator of transcription (STAT)3 pathway is emerging as a target for the treatment of hepatocellular carcinoma. IL-6 binds to IL-6R, forming a binary complex, which further combines with GP130 to transduce extracellular signaling by activating STAT3. Therefore, blocking the interaction between IL-6 and GP130 may inhibit the IL-6/GP130/STAT3 signaling pathway and its biological effects. It has been reported that bazedoxifene acetate (BAZ), a selective estrogen receptor modulator approved by the US Food and Drug Administration, could inhibit IL-6/GP130 protein-protein interactions. Western blot, immunofluorescence staining, wound healing and colony formation assays were used to detect the effect of BAZ on liver cancer cells. Cell viability was evaluated by MTT assay. Apoptosis of cells was determined using the Annexin V-FITC detection kit. Mouse xenograft tumor models were utilized to evaluate the effect of BAZ in vivo. Our data showed that BAZ inhibited STAT3 phosphorylation (P-STAT3) and expression of STAT3 downstream genes, inducing apoptosis in liver cancer cells. BAZ inhibited P-STAT3 induced by IL-6, but not by leukemia inhibitory factor. BAZ inhibited P-STAT1 and P-STAT6 less significantly as elicited by interferon-α, interferon-γ and IL-4. In addition, pretreatment of BAZ impeded the translocation of STAT3 to nuclei induced by IL-6. BAZ inhibited cell viability, wound healing and colony formation in vitro. Furthermore, tumor growth in HEPG2 mouse xenografts were significantly inhibited by daily intragastric gavage of BAZ. Our results suggest that BAZ inhibited the growth of hepatocellular carcinoma in vitro and in vivo, indicating another potential strategy for HCC prevention and therapy.

Bazedoxifene is a novel IL-6/GP130 inhibitor for treating triple-negative breast cancer.

PURPOSE: Triple-negative breast cancer (TNBC) has been ranked as one of the devastating malignancy worldwide. Its disease progression and treatment obstacle is associated with the negligible expression of estrogen receptors (ER-), progesterone receptors (PR-), and HER2 (HER2-). Due to a lack of growth hormone receptors, TNBC is desperately demanding effective therapeutic regimens. A growing body of evidence indicated that glycoprotein 130 kDa (GP130), the pivotal mediator involved in interleukin 6 (IL-6) and signal transducer and activator of transcription 3 (STAT3) signaling pathways, is strongly correlated with tumor progression. Therefore, GP130 could become a novel target for treating TNBC. In our earlier studies, we demonstrated bazedoxifene as being a novel GP130 inhibitor. METHODS: In the current report, anti-tumor effect of bazedoxifene on TNBC was further evaluated in TNBC cell lines SUM159, MDA-MB-231, and MDA-MB-468. We assessed anti-TNBC potency of bazedoxifene by carrying out various analysis encompassing western blot, cell proliferation, cell migration, colony formation, and growth of tumors in the xenograft mice. RESULTS: Our findings demonstrated that bazedoxifene not only decreased the expression of P-STAT3, IL-6/GP130-mediated downstream target genes P-AKT and P-ERK, but also blocked mitogen effects stimulated by IL-6, including cell viability, and overall cell survive, proliferation as well as cell migration. Likewise in laboratory animal model, tumor growth in mice was remarkably suppressed by bazedoxifene via an oral administration route. Combinational treatment of bazedoxifene plus the conventional chemotherapeutic agent, paclitaxel, synergistically impeded cell viability, colony formation, and cell migration far more significantly than the one from single-drug alone. CONCLUSIONS: Taken together, our data suggest that bazedoxifene may be developed as a promising small molecular therapeutic agent for eradicating TNBC intrinsically associated with constitutively active IL-6/GP130/STAT3 signaling cascade.

Bazedoxifene Ameliorates Homocysteine-Induced Apoptosis via NADPH Oxidase-Interleukin 1ß and 6 Pathway in Osteocyte-like Cells.

Homocysteine (Hcy) increases oxidation and inflammation; however, the mechanism of Hcy-induced bone fragility remains unclear. Because selective estrogen modulators (SERMs) have an anti-oxidative effect, SERMs may rescue the Hcy-induced bone fragility. We aimed to examine whether oxidative stress and pro-inflammatory cytokines such as interleukin (IL)-1ß and IL-6 are involved in the Hcy-induced apoptosis of osteocytes and whether bazedoxifene (BZA) inhibits the detrimental effects of Hcy. We used mouse osteocyte-like cell lines MLO-Y4-A2 and Ocy454. Apoptosis was examined by DNA fragmentation ELISA and TUNEL staining, and gene expression was evaluated by real-time PCR. Hcy 5 mM significantly increased expressions of NADPH oxidase (Nox)1, Nox2, IL-1ß, and IL-6 as well as apoptosis in MLO-Y4-A2 cells. Nox inhibitors, diphenyleneiodonium chloride and apocynin, significantly suppressed Hcy-induced IL-1ß and IL-6 expressions. In contrast, an IL-1ß receptor antagonist and an IL-6 receptor monoclonal antibody had no effects on Hcy-induced Nox1 and Nox2 expressions, but significantly rescued Hcy-induced apoptosis. BZA (1 nM-1 µM) and 17ß estradiol 100 nM significantly rescued Hcy-induced apoptosis, while an estrogen receptor blocker ICI 182,780 reversed the effects of BZA and 17ß estradiol. BZA also rescued Hcy-induced apoptosis of Ocy454 cell, and ICI canceled the effect of BZD. Moreover, BZA significantly ameliorated Hcy-induced expressions of Nox1, Nox2, IL-1ß, and IL-6, and ICI canceled the effects of BZA on their expressions. Hcy increases apoptosis through stimulating Nox 1 and Nox 2-IL-1ß and IL-6 expressions in osteocyte-like cells. BZA inhibits the detrimental effects of Hcy on osteocytes via estrogen receptor.

Bazedoxifene protects cerebral autoregulation after traumatic brain injury and attenuates impairments in blood-brain barrier damage: involvement of anti-inflammatory pathways by blocking MAPK signaling.

OBJECTIVE: Traumatic brain injury (TBI) is a significant cause of death and long-term deficits in motor and cognitive functions for which there are currently no effective chemotherapeutic drugs. Bazedoxifene (BZA) is a third-generation selective estrogen receptor modulator (SERM) and has been investigated as a treatment for postmenopausal osteoporosis. It is generally safe and well tolerated, with favorable endometrial and breast safety profiles. Recent findings have shown that SERMs may have therapeutic benefits; however, the role of BZA in the treatment of TBI and its molecular and cellular mechanisms remain poorly understood. The aim of the present study was to examine the neuroprotective effects of BZA on early TBI in rats and to explore the underlying mechanisms of these effects. MATERIALS AND METHODS: TBI was induced using a modified weight-drop method. Neurological deficits were evaluated according to the neurological severity score (NSS). Morris water maze and open-field behavioral tests were used to test cognitive functions. Brain edema was measured by brain water content, and impairments in the blood-brain barrier (BBB) were evaluated by expression analysis of tight junction-associated proteins, such as occludin and zonula occludens-1 (ZO-1). Neuronal injury was assessed by hematoxylin and eosin (H&E) staining. LC-MS/MS analysis was performed to determine the ability of BZA to cross the BBB. RESULTS: Our results indicated that BZA attenuated the impaired cognitive functions and the increased BBB permeability of rats subjected to TBI through activation of inflammatory cascades. In vivo experiments further revealed that BZA provided this neuroprotection by suppressing TBI-induced activation of the MAPK/NF-κB signaling pathway. Thus, mechanically, the anti-inflammatory effects of BZA in TBI may be partially mediated by blocking the MAPK signaling pathway. CONCLUSIONS: These findings suggest that BZA might attenuate neurological deficits and BBB damage to protect against TBI by blocking the MAPK/NF-κB signaling pathway.

Beyond estrogen: advances in tissue selective estrogen complexes and selective estrogen receptor modulators.

Selective estrogen receptor modulators (SERMs) are synthetic non-steroidal agents which have variable estrogen agonist and antagonist activities in different target tissues. Tamoxifen is an anti-estrogen in the breast used for treatment and prevention of breast cancer, with estrogen agonist activity in the uterus. Raloxifene prevents and treats osteoporosis and prevents breast cancer, and can be safely combined with vaginal but not systemic estrogen. The tissue selective estrogen complex combines conjugated equine estrogens (CEE) with the SERM bazedoxifene (BZA). The five Selective Estrogen Menopause and Response to Therapy studies, with up to 2 years of data, demonstrated that CEE/BZA 0.45 mg/BZA 20 mg improved vasomotor symptoms and vulvovaginal atrophy, prevented bone loss, and was neutral on breast tenderness, breast density, with breast cancer incidence similar to placebo. Protection against estrogen-induced endometrial hyperplasia and cancer was found, with similar amenorrhea rates to placebo. Ospemifene is approved to treat dyspareunia, with potential benefits on bone and the breast, while lasofoxifene is being developed to treat resistant estrogen receptor-positive breast cancer in women. Estetrol is an estrogen synthesized exclusively during pregnancy by the human fetal liver and initially considered a weak estrogen, but it appears to have dual weak estrogenic/anti-estrogenic features.

Effects of bazedoxifene/conjugated estrogens on reproductive endocrinology and reproductive tract ultrasonographic appearance in premenopausal women: a preliminary study.

Bazedoxifene (BZA) paired with conjugated estrogens (CE) is the first tissue selective estrogen receptor complex (TSEC) approved by the United States Food and Drug Administration for the treatment of menopausal symptoms. Clinical trials in menopausal women and in premenopausal murine models of endometriosis have demonstrated safety and efficacy, however, the impact of BZA/CE on premenopausal women is not known. Here we report a case series study in premenopausal women assessing effects of BZA/CE on reproductive hormones, and uterine/ovarian ultrasonographic appearance. After one monitoring cycle, five subjects underwent daily administration of BZA/CE (20 mg/0.45 mg) for 12 weeks, and were followed for 4 weeks after treatment. Uterine/ovarian morphology was assessed with ultrasound, and endocrinologic function with ovulation prediction kits and serum assessment of reproductive hormones throughout the menstrual cycle. All subjects demonstrated an LH surge on the medication; interestingly there was a significant decrease in luteinizing hormone level during treatment compared to posttreatment values. BZA/CE was well-tolerated in premenopausal women and did not induce clinically relevant reproductive hormone changes, endometrial alterations, or abnormal ovarian folliculogenesis.

Effect of a tissue selective estrogen complex on breast cancer: Role of unique properties of conjugated equine estrogen.

The Women's Health Initiative studies reported that the menopausal hormone therapy (MHT) regimen containing conjugated equine estrogen (CEE) and medroxyprogesterone acetate increased, whereas CEE alone reduced breast cancer incidence. These observations suggest the possibility that CEE might exert unique actions on breast and also suggest the need to eliminate the progestogen from MHT regimens. A MHT regimen called a tissue selective estrogen complex (TSEC), containing CEE plus bazedoxifene (BZA), to avoid the need for a progestogen, was developed and FDA approved. Our study addressed two questions regarding this TSEC: (i) whether CEE exert effects on breast cancer which differ from those of estradiol (E2 ) and (ii) whether BZA antagonize the effects of E2 and CEE on breast cancer? Two rodent models (NMU and ACI) were used to compare the effect of CEE with E2 on mammary tumor formation, proliferation and apoptosis. In both the NMU and ACI models, E2 significantly increased tumor incidence and multiplicity whereas in striking contrast CEE did not, even though the estrogenic effects of CEE and E2 on uterine weight were identical. Mechanistically E2 blocked whereas CEE stimulated apoptosis (cleaved caspase-3) in ACI animals and only E2 stimulated proliferation (Ki67). BZA exerted highly potent anti-estrogenic effects on tumors by completely blocking palpable tumor formation. These data suggest that the CEE/BZA TSEC may be a safer, breast-antagonistic, MHT agent for women and might have potential to prevent breast cancer while relieving menopausal symptoms.

Down-regulating IL-6/GP130 targets improved the anti-tumor effects of 5-fluorouracil in colon cancer.

Recent studies have confirmed that IL-6/GP130 targets are closely associated with tumor growth, metastasis and drug resistance. 5-Fluorouracil (5-FU) is the most common chemotherapeutic agent for colon cancer but is limited due to chemoresistance and high cytotoxicity. Bazedoxifene (BZA), a third-generation selective estrogen receptor modulator, was discovered by multiple ligand simultaneous docking and drug repositioning approaches to have a novel function as an IL-6/GP130 target inhibitor. Thus, we speculated that in colon cancer, the anti-tumor efficacy of 5-FU might be increased in combination with IL-6/GP130 inhibitors. CCK8 assay and colony formation assay were used to detect the cell proliferation and colony formation. We measured the IC50 value of 5-FU alone and in combination with BZA by cell viability inhibition. Cell migration and invasion ability were tested by scratch migration assays and transwell invasion assays. Flow cytometric analysis for cell apoptosis and cell cycle. Quantitative real-time PCR was used to detect Bad, Bcl-2 and Ki-67 mRNA expression and western blotting (WB) assay analyzed protein expression of Bad/Bcl-2 signaling pathway. Further mechanism study, WB analysis detected the key proteins level in IL-6/GP130 targets and JAK/STAT3, Ras/Raf/MEK/ERK, and PI3K/AKT/mTOR signaling pathway. A colon cancer xenograft model was used to further confirm the efficacy of 5-FU and BZA in vivo. The GP130, P-STAT3, P-AKT, and P-ERK expression levels were detected by immunohistochemistry in the xenograft tumor. BZA markedly potentiates the anti-tumor function of 5-FU in vitro and in vivo. Conversely, 5-FU activation is reduced following exogenous IL-6 treatment in cells. Further mechanistic studies determined that BZA treatment enhanced 5-FU anti-tumor activation by inhibiting the IL-6/GP130 signaling pathway and the phosphorylation status of the downstream effectors AKT, ERK and STAT3. In contrast, IL-6 can attenuate 5-FU function via activating IL-6R/GP130 signaling and the P-AKT, P-ERK and P-STAT3 levels. This study firstly verifies that targeting IL-6/GP130 signaling can increase the anti-tumor function of 5-FU; in addition, this strategy can sensitize cancer cell drug sensitivity, implying that blocking IL-6/GP130 targets can reverse chemoresistance. Therefore, combining 5-FU and IL-6/GP130 target inhibitors may be a promising approach for cancer treatment.

Selective estrogen receptor modulators and the vitamin D analogue eldecalcitol block bone loss in male osteoporosis.

Rapid increases in the number of elderly people have dramatically increased the number of female and male osteoporosis patients. Osteoporosis often causes bone fragility fractures, and males exhibit particularly poor prognosis after these fractures, indicating that control of osteoporosis is crucial to maintain quality of men's lives. However, osteoporosis therapies available for men have lagged behind advances available for women. Here, we show that three selective estrogen receptor modulators (SERMs), namely, raloxifene, bazedoxifene, and tamoxifen, plus the vitamin D analogue ED71, also called eldecalcitol, completely block orchiectomy-induced, testosterone-depleted bone loss in male mice in vivo. Patients treated with hormone deprivation therapy for prostate cancer also exhibit male osteoporosis, and bone management is critical for these patients. Given that androgen replacement therapy is not an option for these patients, our results represent a novel approach potentially useful to control male osteoporosis.