Erb-041, an estrogen receptor-β agonist, inhibits skin photocarcinogenesis in SKH-1 hairless mice by downregulating the WNT signaling pathway

Synergistic Anti-Cancer Effects of ERB-041 and Genistein through Estrogen Receptor Suppression-Mediated PI3K/AKT Pathway Downregulation in Canine Mammary Gland Tumor Cells

Canine-mammary-gland tumors (CMTs) are prevalent in female dogs, with approximately 50% of them being malignant and often presenting as inoperable owing to their size or metastasis. Owing to poor outcomes, effective alternatives to conventional chemotherapy for humans are necessary. Two estrogen receptors, estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which act in opposition to each other, are involved, and CMT growth involves ERα through the phosphoinositide 3-kinases (PI3K)/AKT pathway. In this study, we aimed to identify the synergistic anti-cancer effects of ERB-041, an ERβ agonist, and genistein, an isoflavonoid from soybeans known to have ERβ-specific pseudo-estrogenic actions, on CMT-U27 and CF41.Mg CMT cell lines. ERB-041 and genistein synergistically inhibited cell proliferation and increased the number of annexin V-positive cells in both cell lines. Furthermore, we observed a synergistic increase in the Bax/Bcl-2 ratio and cleaved caspase-3 expression. Additionally, cell-cycle arrest occurred through the synergistic regulation of cyclin D1 and cyclin-dependent kinase 4 (CDK4). We also found a synergistic decrease in the expression of ERα, and the expression of proteins involved in the PI3K/AKT pathway, including p-PI3K, phosphatase and tensin homolog (PTEN), AKT, and mechanistic target of rapamycin (mTOR). In conclusion, ERB-041 and genistein exhibited a synergistic anticancer effect on CMTs, suggesting that cotreatment with ERB-041 and genistein is a promising treatment for CMTs.

Nutraceutical strategies for alleviation of UVB phototoxicity

Ultraviolet B exposure to keratinocytes promotes carcinogenesis by inducing pyrimidine dimer lesions in DNA, suppressing the nucleotide excision repair mechanism required to fix them, inhibiting the apoptosis required for the elimination of initiated cells, and driving cellular proliferation. Certain nutraceuticals - most prominently spirulina, soy isoflavones, long-chain omega-3 fatty acids, the green tea catechin epigallocatechin gallate (EGCG) and Polypodium leucotomos extract - have been shown to oppose photocarcinogenesis, as well as sunburn and photoaging, in UVB-exposed hairless mice. It is proposed that spirulina provides protection in this regard via phycocyanobilin-mediated inhibition of Nox1-dependent NADPH oxidase; that soy isoflavones do so by opposing NF-κB transcriptional activity via oestrogen receptor-beta; that the benefit of eicosapentaenoic acid reflects decreased production of prostaglandin E2; and that EGCG counters UVB-mediated phototoxicity via inhibition of the epidermal growth factor receptor. The prospects for practical nutraceutical down-regulation of photocarcinogenesis, sunburn, and photoaging appear favourable.

Conformationally Defined Rexinoids for the Prevention of Inflammation and Nonmelanoma Skin Cancers

Compound 1 is a potent rexinoid that is highly effective in cancer chemoprevention but elevates serum triglycerides. In an effort to separate the lipid toxicity from the anticancer activity of 1, we synthesized four new analogs of rexinoid 1, of which three rexinoids did not elevate serum triglycerides. Rexinoids 3 and 4 are twice as potent as rexinoid 1 in binding to Retinoid X receptor (RXR). All-trans retinoic acid (ATRA) plays a key role in maintaining skin homeostasis, and rexinoids 3-6 are highly effective in upregulating the genes responsible for the biosynthesis of ATRA. Inflammation plays a key role in skin cancer, and rexinoids 3 and 4 are highly effective in diminishing LPS-induced inflammation. Rexinoids 3 and 4 are highly effective in preventing UVB-induced nonmelanoma skin cancer (NMSC) without displaying any overt toxicities. Biophysical studies of rexinoids 3 and 5 bound to hRXRα-ligand binding domain (LBD) reveal important conformational and dynamical differences in the ligand binding domain.

CYP11A1‑derived vitamin D hydroxyderivatives as candidates for therapy of basal and squamous cell carcinomas

Hydroxyderivatives of vitamin D3, including classical 1,25(OH)2D3 and novel CYP11A1‑derived hydroxyderivatives, exert their biological activity by acting as agonists on the vitamin D receptor (VDR) and inverse agonists on retinoid‑related orphan receptors (ROR)α and γ. The anticancer activities of CYP11A1‑derived hydroxyderivatives were tested using cell biology, tumor biology and molecular biology methods in human A431 and SCC13 squamous (SCC)‑ and murine ASZ001 basal (BCC)‑cell carcinomas, in comparison with classical 1,25(OH)2D3. Vitamin D3‑hydroxyderivatives with or without a C1α(OH) inhibited cell proliferation in a dose‑dependent manner. While all the compounds tested had similar effects on spheroid formation by A431 and SCC13 cells, those with a C1α(OH) group were more potent in inhibiting colony and spheroid formation in the BCC line. Potent anti‑tumorigenic activity against the BCC line was exerted by 1,25(OH)2D3, 1,20(OH)2D3, 1,20,23(OH)3D3, 1,20,24(OH)3D3, 1,20,25(OH)3D3 and 1,20,26(OH)3D3, with smaller effects seen for 25(OH)D3, 20(OH)D3 and 20,23(OH)2D3. 1,25(OH)2D3, 1,20(OH)2D3 and 20(OH)D3 inhibited the expression of GLI1 and β‑catenin in ASZ001 cells. In A431 cells, these compounds also decreased the expression of GLI1 and stimulated involucrin expression. VDR, RORγ, RORα and CYP27B1 were detected in A431, SCC13 and ASZ001 lines, however, with different expression patterns. Immunohistochemistry performed on human skin with SCC and BCC showed nuclear expression of all three of these receptors, as well as megalin (transmembrane receptor for vitamin D‑binding protein), the level of which was dependent on the type of cancer and antigen tested in comparison with normal epidermis. Classical and CYP11A1‑derived vitamin D3‑derivatives exhibited anticancer‑activities on skin cancer cell lines and inhibited GLI1 and β‑catenin signaling in a manner that was dependent on the position of hydroxyl groups. The observed expression of VDR, RORγ, RORα and megalin in human SCC and BCC suggested that they might provide targets for endogenously produced or exogenously applied vitamin D hydroxyderivatives and provide excellent candidates for anti‑cancer therapy.

Update on Melasma-Part I: Pathogenesis

Melasma is a multifactorial dyschromia that results from exposure to external factors (such as solar radiation) and hormonal factors (such as sex hormones and pregnancy), as well as skin inflammation (such as contact dermatitis and esthetic procedures), in genetically predisposed individuals. Beyond hyperfunctional melanocytes, skin with melasma exhibits a series of structural and functional alterations in the epidermis, basement membrane, and upper dermis that interact to elicit and sustain a focal hypermelanogenic phenotype. Evolution in the knowledge of the genetic basis of melasma and the cutaneous response to solar radiation, as well as the roles of endocrine factors, antioxidant system, endothelium proliferation, fibroblast senescence, mast cell degranulation, autophagy deficits of the melanocyte, and the paracrine regulation of melanogenesis, will lead to the development of new treatments and preventive strategies. This review presents current knowledge on these aspects of the pathogenesis of melasma and discusses the effects of specific treatments and future research on these issues.

Sex Steroid Receptors in Polycystic Ovary Syndrome and Endometriosis: Insights from Laboratory Studies to Clinical Trials

Polycystic ovary syndrome (PCOS) and endometriosis are reproductive disorders that may cause infertility. The pathology of both diseases has been suggested to be associated with sex steroid hormone receptors, including oestrogen receptors (ER), progesterone receptors (PRs) and androgen receptors (ARs). Therefore, with this review, we aim to provide an update on the available knowledge of these receptors and how their interactions contribute to the pathogenesis of PCOS and endometriosis. One of the main PCOS-related medical conditions is abnormal folliculogenesis, which is associated with the downregulation of ER and AR expression in the ovaries. In addition, metabolic disorders in PCOS are caused by dysregulation of sex steroid hormone receptor expression. Furthermore, endometriosis is related to the upregulation of ER and the downregulation of PR expression. These receptors may serve as therapeutic targets for the treatment of PCOS-related disorders and endometriosis, considering their pathophysiological roles. Receptor agonists may be applied to increase the expression of a specific receptor and treat endometriosis or metabolic disorders. In contrast, receptor antagonist functions to reduce receptor expression and can be used to treat endometriosis and induce ovulation. Understanding PCOS and the pathological roles of endometriosis sex steroid receptors is crucial for developing potential therapeutic strategies to treat infertility in both conditions. Therefore, research should be continued to fill the knowledge gap regarding the subject.

Keratinocyte Carcinoma and Photoprevention: The Protective Actions of Repurposed Pharmaceuticals, Phytochemicals and Vitamins

Simple Summary

Keratinocyte carcinoma is the most common type of cancer. Sun exposure and ultraviolet radiation are significant contributors to the development of carcinogenesis, mediated by DNA damage, increased oxidative stress, inflammation, immunosuppression and dysregulated signal transduction. Photoprevention involves using different compounds to delay or prevent ultraviolet radiation-induced skin cancer. In this review, we look at new avenues for systemic photoprevention that are based on pharmaceuticals, plant-derived phytochemicals and vitamins. We also investigate the mechanisms underlying these strategies for preventing the onset of carcinogenesis.

Abstract

Ultraviolet radiation (UVR) arising from sun exposure represents a major risk factor in the development of keratinocyte carcinomas (KCs). UVR exposure induces dysregulated signal transduction, oxidative stress, inflammation, immunosuppression and DNA damage, all of which promote the induction and development of photocarcinogenesis. Because the incidence of KCs is increasing, better prevention strategies are necessary. In the concept of photoprevention, protective compounds are administered either topically or systemically to prevent the effects of UVR and the development of skin cancer. In this review, we provide descriptions of the pathways underlying photocarcinogenesis and an overview of selected photoprotective compounds, such as repurposed pharmaceuticals, plant-derived phytochemicals and vitamins. We discuss the protective potential of these compounds and their effects in pre-clinical and human trials, summarising the mechanisms of action involved in preventing photocarcinogenesis.

Inhibitory activity of acteoside in melanoma via regulation of the ERβ-Ras/Raf1-STAT3 pathway

BACKGROUND

Melanoma is an aggressive cancer with a rapidly increasing incidence rate worldwide. Acteoside has been shown to have antitumor effects in multiple human cancers; however, the underlying function and mechanisms of acteoside in melanoma remain unclear.

PURPOSE

This study explored the inhibitory effect of acteoside on melanoma and the possible mechanisms.

METHODS

Acteoside (15 mg/kg, 30 mg/kg) was administered to mice daily for 21 days. ICI182,780 (0.5 mg/kg) was intraperitoneally injected 30 min before acteoside administration three times a week to evaluate whether the effects elicited by acteoside were mediated via the estrogen receptor. Tumor growth and metabolism, cardiac function, ROS and apoptosis levels in the spleen, serum inflammatory factors, and immune cells in the spleen were monitored. STAT3, p-STAT3, CD31, and survivin levels in tumor tissues were measured via immunofluorescence. Ras, Raf1, STAT3, p-STAT3, Bcl-2, Bax, cleaved caspase-3, and cleaved caspase-9 levels in tumor tissues were determined via Western Blotting.

RESULTS

The results showed that acteoside inhibited melanoma growth, alleviated inflammation levels in mice, attenuated ROS and apoptosis levels in the spleen, downregulated the levels of CD31, survivin, Ras, Raf1, p-STAT3, and Bcl-2, and upregulated the levels of ERβ, Bax, cleaved caspase-3, and cleaved caspase-9. Moreover, the effect of acteoside was blocked by ICI182,780.

CONCLUSION

Acteoside may promote the apoptosis of tumor cells by regulating the ERβ-Ras/Raf1-STAT3 signaling axis, thus inhibiting the occurrence and development of melanoma.

Genome-wide estrogen receptor β chromatin binding in human colon cancer cells reveals its tumor suppressor activity

Colorectal cancer (CRC) is the third leading cause of cancer death in the western world. In women, menopausal hormone therapy has been shown to reduce CRC incidence by 20%. Studies demonstrate that estrogen activating estrogen receptor beta (ERβ) protects against CRC. ERβ is a nuclear receptor that regulates gene expression through interactions with the chromatin. This molecular mechanism is, however, not well characterized in colon. Here, we present for the first time, the cistrome of ERβ in different colon cancer cell lines. We use cell lines engineered to express ERβ, optimize and validate an ERβ antibody for chromatin-immunoprecipitation (ChIP), and perform ChIP-Seq. We identify key binding motifs, including ERE, AP-1, and TCF sites, and we determine enrichment of binding to cis-regulatory chromatin sites of genes involved in tumor development, cell migration, cell adhesion, apoptosis, and Wnt signaling pathways. We compare the corresponding cistromes of colon and breast cancer and find that they are conserved for about a third of genes, including GREB1, but that ERβ tethering to TCF and KLF family motifs is characteristic for colon. We exemplify upregulation of putative CRC tumor suppressor gene CST5 where ERβ in colon cells binds to cis-regulatory regions nearby (-351 bp) the transcriptional start site. Our work provides a foundation for understanding the mechanism of action of ERβ in CRC prevention.

Silibinin treatment protects human skin cells from UVB injury through upregulation of estrogen receptors

Ultraviolet B (UVB) from the sunlight is a major environmental cause for human skin damages, inducing cell death, inflammation, senescence and even carcinogenesis. The natural flavonoid silibinin, clinically used as liver protectant, has protective effects against UVB-caused skin injury in vivo and in vitro. Silibinin is often classified as a phytoestrogen, because it modulates the activation of estrogen receptors (ERs). However, whether silibinin's estrogenic effect contributes to the skin protection against UVB injury remains to be elucidated. The issue was explored in this study by using the human foreskin dermal fibroblasts (HFF) and human non-malignant immortalized keratinocytes (HaCaT). In HFF, pre-treatment with silibinin rescued UVB-irradiated cells from apoptosis. Interestingly, silibinin increased the whole cellular and nuclear levels of ERα and ERβ in UVB-irradiated cells. Activation of ERs by treatment with estradiol elevated the cell survival and reduced apoptosis in UVB-treated cells. ERα agonist increased cell survival, while its antagonist decreased it. ERβ agonist also increased cell survival, but the antagonist had no effect on cell survival. Transfection of the cells with the small interfering RNAs (si-RNAs) to ERα or ERβ diminished the protective effect of silibinin on UVB-irradiated cells. In UVB-treated HaCaT cells, both ERα and ERβ were increased by silibinin treatment. Inhibition of activation and expression of ERα or ERβ by specific antagonists and si-RNAs, respectively, reduced cell survival in UVB-treated HaCaT cells regardless of silibinin treatment. Taken together, it is summarized that silibinin up-regulates both ERα and ERβ pathways in UVB-treated dermal HFF cells and epidermal HaCaT cells, leading to protection of skin from UVB-damage.

5'-Cap‒Dependent Translation as a Potent Therapeutic Target for Lethal Human Squamous Cell Carcinoma

Skin squamous cell carcinomas (SCCs) are a major cause of death in patients who have undergone or will undergo organ transplantation. Moreover, these neoplasms cause significant disease and economic burden and diminish patients' life quality. However, no effective treatment or intervention strategies are available. In this study, we investigated the pathologic role of 5'-cap translation, which is regulated by the formation of a ternary initiation factor complex involving eIF4E, eIF4G, and eIF4A1. We detected increased expression of phosphorylated eIF4E, eIF4G, and eIF4A1 in human and murine skin SCCs. The increase in these ternary initiation factor complex proteins was associated with enhanced eIF4E translation targets cyclin D1 and c-Myc. Conversely, small interfering RNA-mediated depletion of eIF4E in human SCC cells (A431 and SCC-13) reduced eIF4G and proteins that regulate the cell cycle and proliferation. Notably, inhibition of Raf/MAPK/extracellular signal-regulated kinase signaling decreased eIF4E and phosphorylated eIF4E accumulation and significantly diminished cell-cycle gene expression and tumor volume of A431-derived xenograft tumors. Furthermore, disrupting the eIF4E with an allosteric inhibitor of eIF4E and eIF4G binding, 4EGI-1, decreased the eIF4E/eIF4G expression and reduced the proliferation. Finally, combined inhibition of the Raf/MAPK/extracellular signal-regulated kinase axis and eIF4E impaired 5'-cap‒dependent translation and abrogated tumor cell proliferation. These data demonstrate that 5'-cap‒dependent translation is a potential therapeutic target for abrogating lethal skin SCCs in patients who have undergone or will undergo organ transplantation.

Tumour-suppressive effect of oestrogen receptor β in colorectal cancer patients, colon cancer cells, and a zebrafish model

Oestrogen receptor β (ERβ) has been suggested to have anti-proliferative and anti-tumour effects in breast and prostate cancer cells, but other studies have indicated its tumour-promoting effects. Understanding the complex effects of this receptor in different contexts requires further study. We reported that high ERβ expression is independently associated with improved prognosis in female colorectal cancer (CRC) patients. Herein, we investigated the possible anti-tumour effect of ERβ and its selective agonist. CRC patients with high ERβ expression had significantly higher levels of membrane-associated β-catenin, cysteinyl leukotriene receptor 2 (CysLT₂ R), and 15-hydroxyprostaglandin dehydrogenase (15-PGDH), which have anti-tumour effects, but lower levels of nuclear β-catenin, cysteinyl leukotriene receptor 1 (CysLT₁ R), and cyclooxygenase-2 (COX-2), which have tumour-promoting effects. These interesting findings were further supported by two different publicly available CRC mRNA datasets that showed a significant positive correlation between ERβ expression and 15-PGDH and CysLT₂ R expression and a negative correlation between ERβ expression and β-catenin, CysLT₁ R, and COX-2 expression. We next evaluated ERβ expression in three different colon cancer mouse models; ERβ expression was negatively correlated with tumourigenesis. Furthermore, treatment with the ERβ-agonist ERB-041 reduced CysLT₁ R, active β-catenin, and COX-2 levels but increased phospho-β-catenin, CysLT₂ R, and 15-PGDH levels in HCT-116, Caco-2, and SW-480 colon cancer cells compared to vehicle-treated cells. Interestingly, ERB-041-treated cells showed significantly decreased migration, survival, and colonosphere formation and increased apoptotic activity, as indicated by increased CASPASE-3 and apoptotic blebs. Finally, patients with low ERβ expression had significantly more distant metastasis at the time of diagnosis than patients with high ERβ expression. Therefore, we studied the effects of ERB-041-treated colon cancer cells in a zebrafish xenograft model. We found significantly less distant metastasis of ERB-041-treated cells compared to vehicle-treated cells. These results further support ERβ's anti-tumour role in CRC and the possible use of its agonist in CRC patients. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Topical delivery of nordihydroguaretic acid for attenuating cutaneous damage caused by arsenicals

This study evaluated the topical delivery of nordihydroguaretic acid (NDGA), a molecule that can potentially alleviate cutaneous damage caused by exposure to arsenic warfare chemicals. N-acetylcysteine (NAC 0.2% w/v) was added as an antioxidant, preventing the oxidation of NDGA to toxic quinones. A 24 h study was performed to arrive at a minimum concentration of NDGA needed to deliver maximum drug. A solution of 3% w/v delivered the maximum amount of drug at the end of 24 h (37.45 ± 4.32 μg). Short duration studies were carried out to determine the time needed to saturate skin with NDGA. There was no significant difference in the skin concentrations for 24 h and 8 h (14.89 ± 2.36 μg), due to skin saturation. However, there was significant difference in the amount of drug delivered to the epidermis (12.29 ± 1.87 μg) and dermis (2.54 ± 0.56 μg) at the end of 8 h. Solution of NDGA was applied on UV treated skin to assess changes in drug delivery. In vivo studies revealed that 3% NDGA was non-toxic for topical administration.

Endometriosis and pain in the adolescent- striking early to limit suffering: A narrative review

Endometriosis, a condition in which uterine tissue grows outside the uterus, is a debilitating disease, affecting millions of women and costing the United States approximately $78 billion annually in pain- related disability. It is also the leading cause of chronic pelvic pain (CPP), which is often unresponsive to existing treatments. Adolescent women with the disease are at particular risk as there are often significant diagnostic delays, which in turn can exacerbate pain. Research and treatment guidelines for adolescents with endometriosis are largely based on studies for adult women due to the limited number of studies focusing on adolescents. The current paper critically reviews the literature as it pertains to endometriosis pathophysiology, mechanisms contributing to CPP, and treatment implications and recommendations with a focus on gaps related to adolescents.

Silencing of estrogen receptor β promotes the invasion and migration of osteosarcoma cells through activating Wnt signaling pathway

Purpose

This study aimed to evaluate the specific roles of estrogen receptor β (ERβ) on the invasion and migration of osteosarcoma (OS) cells and explore the regulatory mechanisms relating with Wnt signaling pathway.

Methods

The expression of ERβ was detected in human OS tissues by quantitative real-time PCR and immunohistochemistry. U2-OS cells were transfected with siRNA-ERβ (si-ERβ) to downregulate ERβ and treated with FH535 to inhibit Wnt signaling. The migration and invasion ability was detected by scratch and transwell assay, respectively. The expression of β-catenin, MMP-7, and MMP-9 was detected by Western blot. Subcutaneous tumor-bearing model was established by injection of U2-OS cells into mice, and the tumor volumes were measured. Orthotopic transplantation model was established by transplantation of tumor tissues into the liver of mice, and the metastatic tumors were counted.

Results

ERβ was downregulated in human OS tissues and U2-OS cells. The transfection of si-ERβ significantly increased the scratch healing rate; the number of invasion cells; and the expression of β-catenin, MMP-7, and MMP-9 in U2-OS cells. The injection of si-ERβ-transfected U2-OS cells into mice significantly increased the subcutaneous tumor volume; the expression of β-catenin, MMP-7, and MMP-9; and the number of metastatic tumors in liver tissues. The promoting effects of si-ERβ on the invasion and migration of U2-OS cells were significantly reversed by FH535 in vitro and in vivo.

Conclusion

Silencing of ERβ promotes the invasion and migration of OS cells via activating Wnt signaling pathway.

Estrogen receptor subtype agonist activation in human cutaneous squamous cell carcinoma cells modulates expression of CD55 and Cyclin D1

Clinical studies indicate gender bias in cutaneous squamous cell carcinoma (cSCC) incidence with worse prognosis observed in males than in females, suggesting estrogen-mediated protection. In contrast, recent clinical population studies show risk of cSCC by use of oral contraceptives, thus raising controversy. However, animal studies indicate a protective role of estrogen and estrogen receptor (ER)s in cSCC. Currently we have a poor understanding of ERs that are expressed in human cSCC cells and their possible role in malignant transformation. The focus of current study was to determine ER subtype specific expression on cSCC A431 cells and investigate if ER agonist based activation modulates tumor markers CD55 and Cyclin D1 in the cells. ERα, ERβ and G protein-coupled receptor (GPR30) subtype expression at mRNA and protein level was determined in human cSCC A431 cells by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting, respectively. The localization of ER subtypes was determined by confocal microscopy. ER subtype agonist based activation on A431 cells was performed to investigate their role in modulating mRNA and protein expression of tumor markers CD55 and Cyclin D1. A431 cells differentially expressed all three ER subtypes- ERα, ERβ and GPR30 with GPR30 expression being the highest. Confocal studies confirmed that all three ER subtypes were expressed in the cytoplasm and ERα and ERβ lacked nuclear expression. Agonist based activation of both ERα and GPR30 significantly upregulated Cyclin D1 and CD55 expression. Blocking of GPR30 led to significantly downregulation of both Cyclin D1 and CD55 expression. In contrast to ERα and GPR30, ERβ activation significantly downregulated CD55 expression. Taken together, here we demonstrate for the first time that all three ERs- ERα, ERβ and GPR30 are expressed in human A431 cSCC cells and further ER agonist based activation modulates the expression of tumor markers CD55 and Cyclin D1.

The involvement of estrogen receptors α and β in the in vitro effects of 17β-estradiol on secretory profile of peritoneal macrophages from naturally menopausal female and middle-aged male rats

The systemic and extra- gonadal levels of 17β-estradiol (E2) change during aging, and affect the expression of estrogen receptors (ERs) in the immune cells of both females and males. The age-related cessation of ovarian function in females, as well as the tissue-specific expression of enzyme aromatase (estrogen synthase which significantly rises with the advancing age) in both males and females, both determine the concentration of E2 to which immune cells may be exposed. The present study was set up to investigate the direct influence of E2 in vitro on the secretory profile of peritoneal macrophages from young and naturally menopausal female rats, and from young and middle-aged male rats. The involvement of receptor(s) responsible for mediating the effects of E2 in vitro was examined by use of antagonists specific for ERα or ERβ. Whereas in macrophages from young female rats E2 treatment diminished interleukin (IL)-1β secretion, it increased it in young males, and the middle-aged females. The in vitro E2 treatment increased tumor necrosis factor (TNF)-α release by macrophages from young rats of both sexes, while it increased macrophage IL-6 release independently of both sex and age. At the same time, E2 decreased hydrogen peroxide (H₂O₂) production in macrophages from females, and increased it in male rats of both ages, whereas it diminished nitric oxide (NO) release in all experimental groups. Inspite of the sex- and age-specific effects of E2 on macrophage urea release, E2 did not affect the NO/urea ratio in macrophages from female rats, and diminished it in macrophages from both young and middle-aged male rats. Independently of the sex and age, E2 stimulated the release of inflammatory cytokines predominantly via macrophage ERα, and inhibited the IL-1β release in young females via ERβ. In contrast, E2 increased macrophage H₂O₂ and urea production by activating ERβ, but diminished their release via ERα. Our study may contribute to better understanding of the complex role(s) that E2 may play in innate immunity during aging, and that are dependent of sex.

Estrogen receptor modulators genistein, daidzein and ERB-041 inhibit cell migration, invasion, proliferation and sphere formation via modulation of FAK and PI3K/AKT signaling in ovarian cancer

Background

Ovarian cancer is the most lethal gynaecological malignancy. Chemotherapy is the main stay of treatment for metastatic disease, with modest response rates but significant side effects. Therefore, there is a need for alternative therapies that can control the disease while offering good quality of life. Ovarian cancer cells express both estrogen receptor subtypes (ERα and ERβ). There is growing evidence that ERβ is anti-oncogenic. Genistein and daidzein are phytoestrogens found in soybeans and they display higher affinity to bind ERβ. ERB-041 is a potent selective ERβ agonist. In this study, we aimed to investigate the effects of genistein, daidzein and ERB-041 on ovarian cancer.

Methods

Ovarian cancer cell lines were treated with genistein, daidzein and ERB-041 in pharmacological doses. Cell migration, invasion, proliferation, cell cycle arrest, apoptosis and sphere formation were assessed by Transwell migration and invasion assays, XTT assay, focus formation, flow cytometry and sphere formation assay, respectively. Immunoblotting analysis was performed to determine the downstream signaling pathways.

Results

We found that genistein, daidzein and ERB-041 significantly inhibited ovarian cancer cell migration, invasion, proliferation, as well as induced cell cycle arrest and apoptosis. Significantly inhibitory effect on the size and number of sphere formed in genistein, daidzein and ERB-041 treated cells was also demonstrated. Moreover, genistein, daidzein and ERB-041 treatment reduced p-FAK, p-PI3K, p-AKT, p-GSK3β, p21 or cyclin D1 expression in ovarian cancer cells.

Conclusion

Genistein, daidzein and ERB-041 decreased ovarian cancer cell migration, invasion, proliferation and sphere formation, and induced cell cycle arrest and apoptosis with altered FAK and PI3K/AKT/GSK signaling and p21/cyclin D1 expression, suggesting their roles on ovarian cancer cell metastasis, tumorigenesis and stem-like properties and their potential as alternative therapies for ovarian cancer patients.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0559-2) contains supplementary material, which is available to authorized users.

Tea polyphenols for the prevention of UVB-induced skin cancer

Skin cancer is the most common type of cancer with increasing incidence rate and public health burden. Solar ultraviolet (UV) radiation causes an array of damaging cellular and molecular events that eventually lead to the development of skin cancer. Despite increased awareness about sun protection, the exposure rate remains high with less than 15% of men and 30% of women using sunscreen on a regular basis. Therefore, there is an imperative need for the development of novel preventive approaches. Skin cancer chemoprevention using phytochemicals either as dietary supplements or by topical applications has gained considerable attention due to their low toxicity, availability, and anticarcinogenic properties. Tea, the second most commonly consumed beverage in the world, is a rich source of promising phytochemicals known as polyphenols. In this review, we discuss the findings of various in vitro, in vivo and human studies signifying the chemopreventive effects of tea polyphenols against UVB-induced skin cancer. This is accomplished by exploring the role of tea polyphenols in DNA repair, inflammation, oxidative stress, signaling pathways, and epigenetics. Finally, this review discusses a variety of innovative delivery methods that enhance the photochemopreventive effects of tea polyphenols against skin cancer.

Naproxen Inhibits UVB-induced Basal Cell and Squamous Cell Carcinoma Development in Ptch1+/- /SKH-1 Hairless Mice

Naproxen possesses anti-proliferative and pro-apoptotic effects besides its known anti-inflammatory functions. Here, we demonstrate the anticancer effects of naproxen against UVB-induced basal cell carcinoma (BCCs) and squamous cell carcinoma (SCCs) in a highly susceptible murine model of UVB carcinogenesis. Naproxen significantly inhibited UVB-induced BCCs and SCCs in this model. Tumor number and volume were significantly decreased (P < 0.005 and P < 0.05, respectively). Inhibition in UVB-induced SCCs and BCCs was 77% and 86%, respectively, which was associated with reduced PCNA and cyclin D1 and increased apoptosis. As expected, inflammation-related iNOS, COX-2 and nuclear NFκBp65 were also diminished by naproxen treatment. Residual tumors excised from naproxen-treated animal were less invasive and showed reduced expression of epithelial-mesenchymal transition (EMT) markers N-cadherin, Vimentin, Snail and Twist with increased expression of E-cadherin. In BCC and SCC cells, naproxen-induced apoptosis and activated unfolded protein response (UPR) signaling with increased expression of ATF4, p-eIF2α and CHOP. Employing iRNA-based approaches, we found that naproxen-induced apoptosis was regulated by CHOP as sensitivity of these cutaneous neoplastic cells for apoptosis was significantly diminished by ablating CHOP. In summary, these data show that naproxen is a potent inhibitor of UVB-induced skin carcinogenesis. ER stress pathway protein CHOP may play an important role in inducing apoptosis in cancer cells.

Effects of Estrogen Receptor β Stimulation in a Rat Model of Non-Bacterial Prostatic Inflammation

BACKGROUND

There is increasing evidence showing that chronic non-bacterial prostatic inflammation is involved in the pathogenesis of benign prostatic hyperplasia (BPH) and male lower urinary tract symptoms (LUTS). It has also been reported that estrogen receptor β (ERβ) could have an immunoprotective role in prostatic tissue. Therefore, we investigated the effect of ERβ-activation on not only prostatic inflammation, but also bladder overactive conditions in a rat model with nonbacterial prostatic inflammation.

METHODS

Male Sprague-Dawley rats (8 weeks, n = 15) were divided into three groups: sham-saline group (n = 5), formalin-vehicle group (n = 5), and formalin-treatment group (n = 5). The sham-saline group had sham operation and 50 μl normal saline injected into each ventral lobe of the prostate. The formalin-vehicle group had 50 μl 5% formalin injection into bilateral ventral lobes of the prostate. The formalin-treatment group was treated with 3α-Adiol (a selective ERβ agonist precursor) at a dose of 3 mg/kg daily from 2 days before induction of prostatic inflammation, whereas formalin-vehicle rats received vehicle (olive oil). In each group, conscious cystometry was performed on day 28 after intraprostatic formalin injection or sham treatment. After cystometry, the bladder and prostate were harvested for evaluation of mRNA expression and histological analysis.

RESULTS

In cystometric investigation, the mean number of non-voiding contractions was significantly greater and voiding intervals were significantly shorter in formalin-vehicle rats than those in sham-saline rats (P < 0.05). In RT-qPCR analysis, mRNA expression of NGF, P2X2, and TRPA1 receptors was significantly increased in the bladder mucosa, and mRNA expression of TNF-α, iNOS and COX2 in the ventral lobes of prostate was significantly increased in formalin-vehicle rats compared with sham-saline rats (P < 0.05). In addition, relative mRNA expression ratio of ERβ to ERα (ERβ/ERα) in the ventral lobes of prostate was significantly decreased in formalin-vehicle rats compared with sham-saline rats (P < 0.05). These changes were ameliorated by 3α-Adiol administration in formalin-treatment rats.

CONCLUSIONS

These results indicate that ERβ activation by 3α-Adiol administration, which normalized the ERβ/ERα expression ratio in the prostate, can improve not only prostatic inflammation, but also bladder overactivity. Therefore, ERβ agonists might be useful for treating irritative bladder symptoms in patients with symptomatic BPH associated with prostatic inflammation. Prostate 77:803-811, 2017. © 2017 Wiley Periodicals, Inc.

Body mass index and risk of non-melanoma skin cancer: cumulative evidence from prospective studies

Prospective epidemiologic studies that investigated the association between body mass index (BMI) and non-melanoma skin cancer (NMSC) yielded inconsistent findings. A dose-response meta-analysis was conducted to quantitatively summarize the evidence. PubMed and Embase databases were searched for relevant studies. Study-specific relative risk (RR) and 95% confidence interval (CI) for an increase in BMI of 5 kg/m² was computed with the generalized least squares trend estimation, and these risk estimates were combined with the random-effects model. Nine publications were included in the final analyses, consisting of 18 independent cohorts with 22 risk estimates (971,795 participants and 50,561 NMSC cases). Results of the dose-response analyses showed a nonlinear inverse relationship between BMI and NMSC (RR = 0.88, 95% CI: 0.85–0.91, I² = 71.2%, P-nonlinearity <0.001), which persisted when limiting to the studies with adjustment for important potential confounders including sun exposure and sensitivity factors. The risk estimates were very similar for squamous cell carcinoma and basal cell carcinoma. Sex appeared a source of heterogeneity (P-difference = 0.06), with a weaker, but still significant inverse association in men than in women. This dose-response meta-analysis suggests a nonlinear inverse association between BMI and NMSC.

Retinoid X Receptor Agonists Upregulate Genes Responsible for the Biosynthesis of All-Trans-Retinoic Acid in Human Epidermis

UAB30 is an RXR selective agonist that has been shown to have potential cancer chemopreventive properties. Due to high efficacy and low toxicity, it is currently being evaluated in human Phase I clinical trials by the National Cancer Institute. While UAB30 shows promise as a low toxicity chemopreventive drug, the mechanism of its action is not well understood. In this study, we investigated the effects of UAB30 on gene expression in human organotypic skin raft cultures and mouse epidermis. The results of this study indicate that treatment with UAB30 results in upregulation of genes responsible for the uptake and metabolism of all-trans-retinol to all-trans-retinoic acid (ATRA), the natural agonist of RAR nuclear receptors. Consistent with the increased expression of these genes, the steady-state levels of ATRA are elevated in human skin rafts. In ultraviolet B (UVB) irradiated mouse skin, the expression of ATRA target genes is found to be reduced. A reduced expression of ATRA sensitive genes is also observed in epidermis of mouse models of UVB-induced squamous cell carcinoma and basal cell carcinomas. However, treatment of mouse skin with UAB30 prior to UVB irradiation prevents the UVB-induced decrease in expression of some of the ATRA-responsive genes. Considering its positive effects on ATRA signaling in the epidermis and its low toxicity, UAB30 could be used as a chemoprophylactic agent in the treatment of non-melanoma skin cancer, particularly in organ transplant recipients and other high risk populations.

Epithelial turnover in duodenal familial adenomatous polyposis: A possible role for estrogen receptors?

AIM: To investigate estrogen receptors expression in duodenal familial adenomatous polyposis (FAP) and any relationship with epithelial proliferation/apoptosis markers.

METHODS: Twenty-two patients affected by FAP undergoing duodenal resection for malignancies were recruited. Controls were 15 healthy subjects undergoing endoscopy for dyspeptic symptoms. ER-α, ER-α, Ki-67, TUNEL and caspase 3 expression (labeling index: percentage of positive cells) were evaluated by immunohistochemistry or immunofluorescence and examined by light or confocal microscopy. Samples were assigned to four groups: normal tissue, low (LGD) and high-grade dysplasia (HGD), adenocarcinoma (AC). One-way analysis of variance, corrected by Bonferroni’s test, and Pearson’s correlation test were applied for statistical analysis.

RESULTS: ER-beta showed a progressive decline: normal tissue (23.5 ± 4.9), LGD (21.1 ± 4.8), HGD (9.3 ± 3.5), AC (7.1 ± 3.1). The normal tissue of FAP subjects expressed ER-beta like the controls (23.9 ± 6.2). Conversely, ER-α showed a progressive increase from normal tissue (24.8 ± 5.6) to AC (52.0 ± 8.2); the expression in normal tissue was similar to controls (22.5 ± 5.3). Ki67 demonstrated a statistically significant progressive increase at each disease stage up to AC. TUNEL did not reveal differences between controls and normal tissue of FAP subjects, but progressive decreases were observed in LGD, through HGD to AC. Pearson’s correlation test showed a direct relationship between ER-β and TUNEL LI (r = 0.8088, P < 0.0001). Conversely, ER-α was inversely correlated with TUNEL LI (r = - 0.7257, P < 0.0001). The co-expression of ER-β and caspase 3 declined progressively from normal to neoplastic tissue.

CONCLUSION: This study confirmed that ER-β is strongly decreased in duodenal FAP carcinomas, declining in a multiple step fashion, thereby suggesting a putative anti-carcinogenic effect. ER-α showed the opposite trend. ER-β/caspase 3 co-expression suggests this hormone’s possible involvement in apoptosis. Hormonal influences in FAP duodenal tumorigenesis, and modulation of these as a possible chemoprevention strategy, may be a promising approach.

The PARsylation activity of tankyrase in adipose tissue modulates systemic glucose metabolism in mice

AIMS/HYPOTHESIS

Tankyrase (TNKS) is a ubiquitously expressed molecular scaffold that is implicated in diverse processes. The catalytic activity of TNKS modifies substrate proteins through poly-ADP-ribosylation (PARsylation) and is responsive to cellular energetic state. Global deficiency of the TNKS protein in mice accelerates glucose utilisation and raises plasma adiponectin levels. The aim of this study was to investigate whether the PARsylation activity of TNKS in adipocytes plays a role in systemic glucose homeostasis.

METHODS

To inhibit TNKS-mediated PARsylation, we fed mice with a diet containing the TNKS-specific inhibitor G007-LK. To genetically inactivate TNKS catalysis in adipocytes while preserving its function as a molecular scaffold, we used an adipocyte-selective Cre transgene to delete TNKS exons that encoded the catalytic domain at the C-terminus. Tissue-specific insulin sensitivity in mice was investigated using hyperinsulinaemic-euglycaemic clamps. To model adipose-liver crosstalk ex vivo, we applied adipocyte-conditioned media to hepatocytes and assessed the effect on gluconeogenesis.

RESULTS

The TNKS inhibitor G007-LK improved glucose tolerance and insulin sensitivity and promptly increased plasma adiponectin levels. In female mice, but not in male mice, adipocyte-selective genetic inactivation of TNKS catalysis improved hepatic insulin sensitivity and post-transcriptionally increased plasma adiponectin levels. Both pharmacological and genetic TNKS inhibition in female mouse-derived adipocytes induced a change in secreted factors to decrease gluconeogenesis in primary hepatocytes.

CONCLUSIONS/INTERPRETATION

Systemic glucose homeostasis is regulated by the PARsylation activity of TNKS in adipocytes. This regulation is mediated in part by adipocyte-secreted factors that modulate hepatic glucose production. Pharmacological TNKS inhibition could potentially be used to improve glucose tolerance.

Development and Characterization of a Novel in vitro Progression Model for UVB-Induced Skin Carcinogenesis

Epidemiological studies suggest ultraviolet B (UVB) component (290–320 nm) of sun light is the most prevalent etiologic factor for skin carcinogenesis- a disease accounting for more than two million new cases each year in the USA alone. Development of UVB-induced skin carcinoma is a multistep and complex process. The molecular events that occur during UVB-induced skin carcinogenesis are poorly understood largely due to the lack of an appropriate cellular model system. Therefore, to make a progress in this area, we have developed an in vitro model for UVB-induced skin cancer using immortalized human epidermal keratinocyte (HaCaT) cells through repetitive exposure to UVB radiation. We demonstrate that UVB-transformed HaCaT cells gain enhanced proliferation rate, apoptosis-resistance, and colony- and sphere-forming abilities in a progressive manner. Moreover, these cells exhibit increased aggressiveness with enhanced migration and invasive potential and mesenchymal phenotypes. Furthermore, these derived cells are able to form aggressive squamous cell carcinoma upon inoculation into the nude mice, while parental HaCaT cells remain non-tumorigenic. Together, these novel, UVB-transformed progression model cell lines can be very helpful in gaining valuable mechanistic insight into UVB-induced skin carcinogenesis, identification of novel molecular targets of diagnostic and therapeutic significance, and in vitro screening for novel preventive and therapeutic agents.

Estrogen Receptor β Agonists Differentially Affect the Growth of Human Melanoma Cell Lines

Background

Cutaneous melanoma is an aggressive malignancy; its incidence is increasing worldwide and its prognosis remains poor. Clinical observations indicate that estrogen receptor β (ERβ) is expressed in melanoma tissues and its expression decreases with tumor progression, suggesting its tumor suppressive function. These experiments were performed to investigate the effects of ERβ activation on melanoma cell growth.

Methods and Results

Protein expression was analyzed by Western blot and immunofluorescence assays. Cell proliferation was assessed by counting the cells by hemocytometer. ERβ transcriptional activity was evaluated by gene reporter assay. Global DNA methylation was analyzed by restriction enzyme assay and ERβ isoforms were identified by qRT-PCR. We demonstrated that ERβ is expressed in a panel of human melanoma cell lines (BLM, WM115, A375, WM1552). In BLM (NRAS-mutant) cells, ERβ agonists significantly and specifically inhibited cell proliferation. ERβ activation triggered its cytoplasmic-to-nuclear translocation and transcriptional activity. Moreover, the antiproliferative activity of ERβ agonists was associated with an altered expression of G1-S transition-related proteins. In these cells, global DNA was found to be hypomethylated when compared to normal melanocytes; this DNA hypomethylation status was reverted by ERβ activation. ERβ agonists also decreased the proliferation of WM115 (BRAF V600D-mutant) cells, while they failed to reduce the growth of A375 and WM1552 (BRAF V600E-mutant) cells. Finally, we could observe that ERβ isoforms are expressed at different levels in the various cell lines. Specific oncogenic mutations or differential expression of receptor isoforms might be responsible for the different responses of cell lines to ERβ agonists.

Conclusions

Our results demonstrate that ERβ is expressed in melanoma cell lines and that ERβ agonists differentially regulate the proliferation of these cells. These data confirm the notion that melanoma is a heterogeneous tumor and that genetic profiling is mandatory for the development of effective personalized therapeutic approaches for melanoma patients.

Regulation of DNA Damage Response by Estrogen Receptor β-Mediated Inhibition of Breast Cancer Associated Gene 2

Accumulating evidence suggests that ubiquitin E3 ligases are involved in cancer development as their mutations correlate with genomic instability and genetic susceptibility to cancer. Despite significant findings of cancer-driving mutations in the BRCA1 gene, estrogen receptor (ER)-positive breast cancers progress upon treatment with DNA damaging-cytotoxic therapies. In order to understand the underlying mechanism by which ER-positive breast cancer cells develop resistance to DNA damaging agents, we employed an estrogen receptor agonist, Erb-041, to increase the activity of ERβ and negatively regulate the expression and function of the estrogen receptor α (ERα) in MCF-7 breast cancer cells. Upon Erb-041-mediated ERα down-regulation, the transcription of an ERα downstream effector, BCA2 (Breast Cancer Associated gene 2), correspondingly decreased. The ubiquitination of chromatin-bound BCA2 was induced by ultraviolet C (UVC) irradiation but suppressed by Erb-041 pretreatment, resulting in a blunted DNA damage response. Upon BCA2 silencing, DNA double-stranded breaks increased with Rad51 up-regulation and ataxia telangiectasia mutated (ATM) activation. Mechanistically, UV-induced BCA2 ubiquitination and chromatin binding were found to promote DNA damage response and repair via the interaction of BCA2 with ATM, γH2AX and Rad51. Taken together, this study suggests that Erb-041 potentiates BCA2 dissociation from chromatin and co-localization with Rad51, resulting in inhibition of homologous recombination repair.

Estrogen receptor β selective agonists reduce invasiveness of triple-negative breast cancer cells

Metastasis to bone is a frequent problem of advanced breast cancer. Particularly breast cancers, which do not express estrogen receptor α (ERα) and progesterone receptor (PR) and which have no overexpression of human epidermal growth factor receptor 2 (HER2), so-called triple-negative breast cancers (TNBCs), are considered as very aggressive and have a poor prognosis. Recently we have shown that breast cancer cell invasion was dramatically increased when co-cultured with MG63 osteoblast-like cells. Using this model we have now analyzed whether estrogen receptor β (ERβ) plays a role in TNBC cell invasion in vitro. ERα and ERβ protein expression was analyzed using western blot analysis. Invasion was quantified by assessment of TNBC cell migration rate through an artificial basement membrane in a modified Boyden chamber during co-culture with MG63 osteoblast-like cells. The effects of ERβ agonist treatment on CXC motif chemokine receptor 4 (CXCR4) protein expression during co-culture with MG64 cells was quantified using western blot analysis. Proliferation was measured using alamarBlue assay. TNBC cell lines HCC1806 and HCC1937 showed no ERα but high ERβ protein expression. Cell invasion of HCC1806 and HCC1937 TNBC cells was significantly increased when co-cultured with MG63 osteoblast-like cells. Treatment with ERβ selective estrogen agonists liquiritigenin and ERB-041 reduced the ability to invade a reconstituted basement membrane and to migrate in response to the cellular stimulus. During co-culture CXCR4 protein expression of TNBC cell lines HCC1806 and HCC1937 was significantly increased. Treatment with liquiritigenin resulted in a significant decrease of CXCR4 protein expression. Both ERβ agonists showed no effect on TNBC cell proliferation. Our findings suggest that ERβ plays a major role in TNBC invasion. Bone-directed invasion can be inhibited by ERβ agonists.

Estrogen receptors alpha (ERα) and beta (ERβ): subtype-selective ligands and clinical potential

Estrogen receptors alpha (ERα) and beta (ERβ) are nuclear transcription factors that are involved in the regulation of many complex physiological processes in humans. Modulation of these receptors by prospective therapeutic agents is currently being considered for prevention and treatment of a wide variety of pathological conditions, such as, cancer, metabolic and cardiovascular diseases, neurodegeneration, inflammation, and osteoporosis. This review provides an overview and update of compounds that have been recently reported as modulators of ERs, with a particular focus on their potential clinical applications.

Korean Red Ginseng inhibits apoptosis in neuroblastoma cells via estrogen receptor β-mediated phosphatidylinositol-3 kinase/Akt signaling

Background

Ginseng has been shown to exert antistress effects both in vitro and in vivo. However, the effects of ginseng on stress in brain cells are not well understood. This study investigated how Korean Red Ginseng (KRG) controls hydrogen peroxide-induced apoptosis via regulation of phosphatidylinositol-3 kinase (PI3K)/Akt and estrogen receptor (ER)-β signaling.

Methods

Human neuroblastoma SK-N-SH cells were pretreated with KRG and subsequently exposed to H₂O₂. The ability of KRG to inhibit oxidative stress-induced apoptosis was assessed in MTT cytotoxicity assays. Apoptotic protein expression was examined by Western blot analysis. The roles of ER-β, PI3K, and p-Akt signaling in KRG regulation of apoptosis were studied using small interfering RNAs and/or target antagonists.

Results

Pretreating SK-N-SH cells with KRG decreased expression of the proapoptotic proteins p-p53 and caspase-3, but increased expression of the antiapoptotic protein BCL2. KRG pretreatment was also associated with increased ER-β, PI3K, and p-Akt expression. Conversely, ER-β inhibition with small interfering RNA or inhibitor treatment increased p-p53 and caspase-3 levels, but decreased BCL2, PI3K, and p-Akt expression. Moreover, inhibition of PI3K/Akt signaling diminished p-p53 and caspase-3 levels, but increased BCL2 expression.

Conclusion

Collectively, the data indicate that KRG represses oxidative stress-induced apoptosis by enhancing PI3K/Akt signaling via upregulation of ER-β expression.

The therapeutic potential of targeting the epithelial-mesenchymal transition in cancer

INTRODUCTION

The process of epithelial-to-mesenchymal transition (EMT) has long been advocated as a process during tumor progression and the acquisition of metastatic potential of human cancers. EMT has also been linked with resistance to cancer therapies.

AREAS COVERED

Basic research has provided evidence connecting EMT to increased invasion, angiogenesis and metastasis of cancer cells. A number of signaling pathways such as notch, wnt, hedgehog and PI3K-AKT, and various other individual factors therein, have been intricately connected to the onset of EMT. Here, we provide latest updates on the evidences that further highlight an association between various signaling pathways and EMT, with a focus on therapeutic targets that may have the potential to reverse EMT.

EXPERT OPINION

Our understanding of EMT and its underlying causes is rapidly evolving and a number of putative targets have been identified. It is crucial, now than ever before, to design novel translational and clinical studies for the benefit of advanced stage cancer patients with metastatic disease.

Targeting estrogen receptor-β for the prevention of nonmelanoma skin cancer

The potential for targeting estrogen receptor (ER)-β in various cancer models has been gaining considerable attention in recent years. In this issue of the journal, Chaudhary and colleagues demonstrate markedly decreased ultraviolet B (UVB)-induced skin cancer in a mouse model using a highly specific ER-β agonist, ERB-041. The mechanisms that underlie this strong inhibitory effect are mediated by inhibition of proinflammatory signaling and epithelial-mesenchymal transition (EMT). The changes in EMT were due in part to modulation of WNT/β-catenin signaling. Collectively, the results from these studies provide important new insights into the mechanisms by which the ER-β agonist ERB-041 inhibits UVB-induced skin cancer and opens the door for future studies that could examine combinatorial approaches for UVB-dependent skin cancer chemoprevention.