Effects of 17?-estradiol, progesterone, synthetic progestins, tibolone, and raloxifene on vascular endothelial growth factor and Thrombospondin-1 messengerRNA in breast cancer cells

Network pharmacology and topological analysis on tibolone metabolites and their molecular mechanisms in traumatic brain injury

Traumatic brain injury (TBI) is a pathology of great social impact, affecting millions of people worldwide. Despite the scientific advances to improve the management of TBI in recent years, we still do not have a specific treatment that controls the inflammatory process after mechanical trauma. The discovery and implementation of new treatments is a long and expensive process, making the repurpose of approved drugs for other pathologies a clinical interest. Tibolone is a drug in use for the treatment of symptoms associated with menopause and has been shown to have a broad spectrum of actions by regulating estrogen, androgen and progesterone receptors, whose activation exerts potent anti-inflammatory and antioxidant effects. In the present study, we aimed to investigate the therapeutic potential of the tibolone metabolites 3α-Hydroxytibolone, 3β-Hydroxytibolone, and Δ4-Tibolone as a possible therapy in TBI using network pharmacology and network topology analysis. Our results demonstrate that the estrogenic component mediated by the α and β metabolites can regulate synaptic transmission and cell metabolism, while the Δ metabolite may be involved in modulating the post-TBI inflammatory process. We identified several molecular targets, including KDR, ESR2, AR, NR3C1, PPARD, and PPARA, which are known to play critical roles in the pathogenesis of TBI. Tibolone metabolites were predicted to regulate the expression of key genes involved in oxidative stress, inflammation, and apoptosis. Overall, the repurposing of tibolone as a neuroprotective treatment for TBI holds promise for future clinical trials. However, further studies are needed to confirm its efficacy and safety in TBI patients.

Human versus non-human sex steroid use in hormone replacement therapies part 1: Preclinical data

Prior to 2002, hormone replacement therapy (HRT) was considered to be an important component of postmenopausal healthcare. This was based on a plethora of basic, epidemiological and clinical studies demonstrating the health benefits of supplementation with human sex steroids. However, adverse findings from the Women's Health Initiative (WHI) studies that examined the 2 major forms of HRT in use in the US at that time - Premarin (conjugated equine estrogens; CEE) and Prempro (CEE + medroxyprogesterone acetate; MPA), cast a shadow over the use of any form of HRT. Here we review the biochemical and physiological differences between the non-human WHI study hormones - CEE and MPA, and their respective human counterparts 17β-estradiol (E₂) and progesterone (P₄). Preclinical data from the last 30 years demonstrate clear differences between human and non-human sex steroids on numerous molecular, physiological and functional parameters in brain, heart and reproductive tissue. In contrast to CEE supplementation, which is not always detrimental although certainly not as optimal as E₂ supplementation, MPA is clearly not equivalent to P₄, having detrimental effects on cognitive, cardiac and reproductive function. Moreover, unlike P₄, MPA is clearly antagonistic of the positive effects of E₂ and CEE on tissue function. These data indicate that minor chemical changes to human sex steroids result in physiologically distinct actions that are not optimal for tissue health and functioning.

"UPRegulation" of CD47 by the endoplasmic reticulum stress pathway controls anti-tumor immune responses

We recently demonstrated that targeting the unfolded protein response (UPR) protein GRP78 down-regulates CD47 expression, resulting in increased tumor macrophage infiltration and inhibited resistance to anti-estrogen therapy. We now show new data indicating that anti-estrogen therapy regulates CD47 expression and implicates its ligand, thrombospondin-1, in regulation of tumor macrophage infiltration. Moreover, GRP78 and CD47 co-expression is associated with poor prognosis in breast cancer patients, suggesting the existence of crosstalk between UPR and immunity that regulates therapeutic responses in breast cancer.

Molecular expression of vascular endothelial growth factor, prokineticin receptor-1 and other biomarkers in infiltrating canalicular carcinoma of the breast

Vascular endothelial growth factor (VEGF) is important in the growth and metastasis of cancer cells. In 2001, another angiogenic factor, endocrine gland-derived VEGF (EG-VEGF), was characterized and sequenced. EG-VEGF activity appears to be restricted to endothelial cells derived from endocrine glands. At the molecular level, its expression is regulated by hypoxia and steroid hormones. Although VEGF and EG-VEGF are structurally different, they function in a coordinated fashion. Since the majority of mammary tumors are hormone-dependent, it was hypothesized that EG-VEGF would be expressed in these tumors, and therefore, represent a potential target for anti-angiogenic therapy. The aim of the present study was to assess the expression of VEGF, EG-VEGF and its receptor (prokineticin receptor-1), as well as that of breast cancer resistant protein, estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2, in 50 breast samples of infiltrating canalicular carcinoma (ICC) and their correlation with tumor staging. The samples were analyzed using reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. Both angiogenic growth factors were identified in all samples. However, in 90% of the samples, the expression level of VEGF was significantly higher than that of EG-VEGF (P=0.024). There was no association between the expression of VEGF, EG-VEGF or its receptor with tumor stage. In ICC, the predominant angiogenic factor expressed was VEGF. The expression level of either factor was not correlated with the tumor-node-metastasis stage. Although ICC is derived from endothelial cells, EG-VEGF expression was not the predominant angiogenic/growth factor in ICC.

Does hormone therapy, tibolone or raloxifene modify VEGF expression in cervical epithelial cells?

AIM

Vascular endothelial growth factor (VEGF) seems to be a critical molecule in cervical carcinogenesis. We aimed to investigate the possible associations between hormonal factors and VEGF expression in cervical epithelial cells from postmenopausal women.

METHOD

A total of 105 healthy postmenopausal women (aged 45-68 years old) attending a university menopause clinic were enrolled in this cross-sectional study. Pap smears were derived from current users of 17β-estradiol 1 mg + norethisterone acetate 0.5 mg (n = 28), tibolone 2.5 mg (n = 23), raloxifene HCl 60 mg (n = 21) and women not receiving treatment (n = 33). VEGF immunostaining was evaluated in squamous, glandular and metaplastic cells, using a semiquantitative method (rating scale: 0-3).

RESULTS

Concerning endogenous hormones, higher Δ4-androstenedione levels were associated with more intense VEGF immunostaining in glandular (p = 0.041) and metaplastic cells (p = 0.004). Hormone therapy and raloxifene did not induce any changes in VEGF immunoreactivity in the examined cells. In contrast, tibolone administration was accompanied by diminished VEGF presence in metaplastic cells (p = 0.016 vs. controls).

CONCLUSION

Our findings may in part reflect the molecular processes contributing to the safe profile of hormone therapy, tibolone and raloxifene in cervical carcinogenesis.

The combination of VEGF inhibitors and anti-oestrogen therapies in breast cancer

Despite effective treatments for oestrogen receptor-positive breast cancers, drug resistance is common and remains a significant clinical challenge. Targeting tumour vasculature by blockade of the vascular endothelial growth factor (VEGF) has proved successful in a variety of cancers. Phase III clinical trials of bevacizumab in combination with chemotherapy showed some efficacy in breast cancer. Concomitant targeting of the VEGF and oestrogen signalling pathways has the potential to provide enhanced therapeutic benefit in oestrogen receptor-positive breast cancer, and this strategy is under evaluation in clinical trials. This article summarises the rationale for this approach and clinical studies so far.

Synthetic progestins induce growth and metastasis of BT-474 human breast cancer xenografts in nude mice

OBJECTIVE

Previous studies have shown that sequential exposure to estrogen and progesterone or medroxyprogesterone acetate (MPA) stimulates vascularization and promotes the progression of BT-474 and T47-D human breast cancer cell xenografts in nude mice (Liang et al, Cancer Res 2007, 67:9929). In this follow-up study, the effects of progesterone, MPA, norgestrel (N-EL), and norethindrone (N-ONE) on BT-474 xenograft tumors were compared in the context of several different hormonal environments. N-EL and N-ONE were included in the study because synthetic progestins vary considerably in their biological effects and the effects of these two progestins on the growth of human tumor xenografts are not known.

METHODS

Estradiol-supplemented intact and ovariectomized immunodeficient mice were implanted with BT-474 cells. Progestin pellets were implanted simultaneously with estradiol pellets either 2 days before tumor cell injection (ie, combined) or 5 days after tumor cell injections (ie, sequentially).

RESULTS

Progestins stimulated the growth of BT-474 xenograft tumors independent of exposure timing and protocol, MPA stimulated the growth of BT-474 xenograft tumors in ovariectomized mice, and progestins stimulated vascular endothelial growth factor elaboration and increased tumor vascularity. Progestins also increased lymph node metastasis of BT-474 cells. Therefore, progestins, including N-EL and N-ONE, induce the progression of breast cancer xenografts in nude mice and promote tumor metastasis.

CONCLUSIONS

These observations suggest that women who ingest progestins for hormone therapy or oral contraception could be more at risk for developing breast cancer because of proliferation of existing latent tumor cells. Such risks should be considered in the clinical setting.

Sex steroids and breast cancer metastasis

Sex steroids, particularly estrogen and progesterone, promote normal breast tissue growth and differentiation. Prolonged exposure of estrogen and/or progesterone is considered a risk factor for breast cancer carcinogenesis, and the effects of sex steroids on breast cancer metastasis are controversial. Emerging evidence indicates that sex steroids regulate breast cancer metastatic processes via nongenomic and genomic mechanisms. Through the regulation of actin-binding proteins estrogen and progesterone rapidly provoke actin cytoskeleton reorganization in breast cancer cells, leading to formation of membrane structures facilitating breast cancer cell migration and invasion. In addition, steroid receptors interact and trans-activate receptor tyrosine kinases (including epidermal growth factor receptor and insulin-like growth factor receptor), resulting in growth factor-like effects that promote cancer cell invasive behavior. Moreover, sex steroids regulate the expression of metastasis-associated molecules, such as E-cadherin, matrix metalloproteinases, growth factors, chemokines and their receptors, leading to epithelial-to-mesenchymal-like transition. However, there is also evidence that sex steroids and their receptors protect against breast cancer cell invasiveness through distinct mechanisms. Here, we present an overview of the currently identified actions of sex steroids on breast cancer metastasis and their potential clinical implications.

Effect of raloxifene on vascular endothelial growth factor expression in breast carcinomas of postmenopausal women

OBJECTIVE

This study aimed to evaluate the effect of raloxifene on vascular endothelial growth factor (VEGF) expression in breast carcinomas of postmenopausal women.

MATERIALS AND METHODS

Sixteen postmenopausal patients with operable stage II, oestrogen receptor-positive, infiltrating ductal breast carcinoma were treated with raloxifene at a dose of 60 mg/day, for a period of 28 days prior to definitive surgery. Tumour size varied from 3 to 5 cm (mean 3.7 cm) and mean age of patients was 61.8 years (range 49-72 years). Tumour samples were obtained by incisional biopsy at the time of diagnosis and again at the time of surgery. Immunohistochemical evaluation of VEGF expression was assessed semiquantitatively based on fraction of stained tumour cells and on intensity of staining. McNemar's test of symmetry was used to evaluate agreement between positive or negative classification of VEGF expression prior to and following raloxifene treatment (P < 0.05).

RESULTS

Fourteen of the 16 patients (88%) were classified as positive for VEGF expression prior to raloxifene treatment, while only 5 (31%) were classified as positive following treatment (P < 0.007).

CONCLUSION

Raloxifene significantly reduced VEGF expression in these oestrogen receptor-positive breast carcinomas of postmenopausal women.

Role of prolactin and vasoinhibins in the regulation of vascular function in mammary gland

The formation of new blood vessels has become a major focus of mammary gland research stimulated by the therapeutic opportunities of controlling angiogenesis in breast cancer. Normal growth and involution of the mammary gland are profoundly affected by the expansion and regression of blood vessels, whereas dysregulation of angiogenesis is characteristic of breast cancer growth and metastasis. Prolactin stimulates the growth and differentiation of the mammary gland under normal conditions, but its role in breast cancer is controversial. Its action is complicated by the fact that prolactin itself is angiogenic, but proteases cleave prolactin to generate vasoinhibins, a family of peptides that act on endothelial cells to suppress angiogenesis and vasodilation and to promote apoptosis-mediated vascular regression. This review summarizes our current knowledge about the vascular effects of prolactin and the generation and action of vasoinhibins, and discusses their possible contribution to the regulation of blood vessels in the normal and malignant mammary gland.

Upregulation of protein S by progestins

BACKGROUND

Users of progestin-only contraceptives have raised protein S (PS) levels compared with baseline. This contrasts with the reduction in PS levels observed in users of combined oral contraceptives, which contain both a progestin and an estrogen.

OBJECTIVES

To determine the effect of progesterone and other progestin isoforms on the expression of PS and to describe the mechanism involved.

METHODS

Promoter activity of the PROS1 gene that encodes PS was assessed in vitro using breast and liver carcinoma cell lines grown in the presence of various progestins, with and without the addition of excess progesterone receptors. An electromobility shift assay (EMSA) was also performed to identify the progesterone receptor binding element.

RESULTS

PROS1 transcriptional levels were directly upregulated by 25% by progesterone via a mechanism that was progesterone receptor isoform B (PR-B)-dependent. The process was blocked by the progesterone receptor modulator RU486. Results for the EMSA demonstrated that a probe comprising nucleotides -397 to -417 of the PROS1 promoter bound to ligand-activated PR-B, suggesting that the domain is a progesterone response element (PRE). The type of progestin isoform greatly influenced the level of PROS1 promoter upregulation, with medroxyprogesterone able to stimulate a > 2-fold stronger response compared with progesterone.

CONCLUSIONS

The PROS1 promoter is responsive to progesterone and other progestins via a mechanism involving PR-B interacting with a PRE. The type of progestin is important as some elicit stronger upregulatory effects than others, which may influence the choice of progestin used for hormonal contraception by PS-deficient individuals.