Estrogen, Estrogen Receptor and Lung Cancer

Hormone receptor expression correlates with EGFR gene mutation in lung cancer in patients with simultaneous primary breast cancer

Background

The coexistence of double primaries of lung cancer (LC) and breast cancer (BC) are not uncommon in women, but there has been limited research conducted of their molecular association. To decipher the internal pathogenesis of LC in patients with concurrent BC and LC, this study explored the clinical factors and relationship between hormone receptor (HR) expression and epidermal growth factor receptor (EGFR) gene mutation.

Methods

The clinicopathological characteristics of 400 female patients clinically diagnosed with double primary LC and BC at Fudan University Shanghai Cancer Center were collected. Pathological discrimination was performed to further confirm the double primaries in patients with available tissues. LC samples were then examined to detect EGFR gene mutation status by PCR-based assays and HR expression by immunohistochemistry (IHC). As a control cohort, the characteristics of 114 consecutive patients with LC only were compared with the double-primary patient group.

Results

A total of 169 patients were pathologically confirmed with simultaneous LC and BC between January 2010 and October 2018. The dominant LC subtype was adenocarcinoma (ADC) (95.1%), and invasive ductal carcinoma (IDC) was the main BC subtype (71.0%). Synchronous and metachronous double primary BC-LC cases accounted for 39.1% and 60.9% of the patients, respectively. The absence of family cancer history was associated with a shorter interval between the two primary cancer diagnoses. Among 64 patients with EGFR mutations, 34.4% had HR-positive LC tissue, compared with 0/24 (0%) of those with EGFR wild-type LC (P<0.001). All of the patients with positive HR expression harbored an activating EGFR mutation (n=22); however, no correlation was observed in the control cohort.

Conclusions

Double primary BC-LC patients have distinctive clinicopathological features compared to those with LC only. The expression of HRs is significantly correlated with EGFR mutation status of LC tissues.

Epidemiology of lung cancer in Northern Greece: An 18-year hospital-based cohort study focused on the differences between smokers and non-smokers

INTRODUCTION

Lung cancer remains a leading cause of cancer incidence, yet, in Greece, country-level registry-based data are limited. We have thus investigated the epidemiology of lung cancer and its trends in the George Papanikolaou Hospital, Northern Greece over 18 years (2000–2018).

METHODS

We analyzed all the cases reported in the Bronchoscopy Unit of the Hospital for the period 2000–2018. In total, 15131 subjects (12300 males and 2831 females) that presented with a mass in the imaging, were submitted to bronchoscopy. Characteristics of patients such as age, sex, smoking history and occupation were collected. Statistical analysis was performed with SPSS 21.0 software package.

RESULTS

Among all subjects, a total of 5628 (37.2%; mean age: 65.85 ± 9.6 years) cases of primary lung cancer were identified with a male to female ratio of 2:1 (41.1% to 20.4%) (p<0.001). Squamous cell lung cancer was the most common type of lung cancer identified in this population (44%) with a higher proportion in males compared to females (p<0.001). Furthermore, adenocarcinoma was mostly observed in female non-smokers compared to males (p<0.001). The majority of lung cancer cases were identified in patients occupied with agriculture and livestock breeding (41.1%). The mean age at lung cancer diagnosis was 66.13 ± 9.19 years for the whole study population. Lung cancer cases observed with a higher mean of 43.93 ± 10.84 years of smoking compared to cancer-free patients with 39.64 ± 13.23 years of smoking (p<0.001).

CONCLUSIONS

Apart from smoking, demographic characteristics including age, sex and occupation appear to have an impact on lung cancer development in this population. Smoking history alone could not predict the development of lung cancer in the studied northern Greek population.

Risk of Osteoporotic Fracture in Patients with Breast Cancer: Meta-Analysis

Background

The fracture risk induced by anti-estrogen therapy in patients with breast cancer remains controversial. The aim of this study was to perform a meta-analysis and systematic review to evaluate the risk of osteoporotic fracture in patients with breast cancer.

Methods

A systematic search was performed to identify studies that included any osteoporotic fracture (hip fracture and vertebral fracture) in patients breast cancer. Main outcome measures were occurrence and risk of osteoporotic fractures including hip and vertebral fractures in patients and controls.

Results

A systematic search yielded a total of 4 studies that included osteoporotic fracture outcomes in patients with breast cancer. Meta-analysis showed a higher risk of osteoporotic fracture in patients with breast cancer. Analysis of these 4 studies involving a total of 127,722 (23,821 cases and 103,901 controls) patients showed that the incidence of osteoporotic fractures was higher in the breast cancer group than in the control group. The pooled estimate of crude relative risk for osteoporotic fracture was 1.35 (95% confidence interval, 1.29-1.42; P<0.001).

Conclusions

Although studies were limited by a small number, results suggested a possible association between anti-estrogen therapy and increased risk of osteoporotic fractures in patients with breast cancer.

Altered expression of 17‑β‑hydroxysteroid dehydrogenase type 2 and its prognostic significance in non‑small cell lung cancer

Numerous studies have reported that oestrogens may contribute to the development of non small cell lung cancer (NSCLC). Although different steroidogenic enzymes have been detected in the lung, the precise mechanism leading to an exaggerated accumulation of active oestrogens in NSCLC remains unexplained. 17 β Hydroxysteroid dehydro genase type 2 (HSD17B2) is an enzyme involved in oestrogen and androgen inactivation by converting 17 β oestradiol into oestrone, and testosterone into 4 androstenedione. Therefore, the enzyme serves an important role in regulation of the intra cellular availability of active sex steroids. This study aimed to determine the expression levels of HSD17B2 in lung cancer (LC) and adjacent histopathologically unchanged tissues obtained from 161 patients with NSCLC, and to analyse the association of HSD17B2 with clinicopathological features. For that purpose, reverse transcription quantitative PCR, western blotting and immunohistochemistry were conducted. The results revealed that the mRNA and protein expression levels of HSD17B2 were significantly decreased in LC tissues compared with matched controls (P<10 ⁶). Conversely, strong cytoplasmic staining of HSD17B2 was detected in the unchanged respiratory epithelium and in glandular cells. Notably, a strong association was detected between reduced HSD17B2 expression and advanced tumour stage, grade and size. Furthermore, it was revealed that HSD17B2 may have potential prognostic significance in NSCLC. A log-rank test revealed the benefit of high HSD17B2 protein expression for the overall survival (OS) of patients (P=0.0017), and multivariate analysis confirmed this finding (hazard ratio=0.21; 95% confidence interval=0.07-0.63; P=0.0043). Stratified analysis in the Kaplan Meier Plotter database indicated that patients with higher HSD17B2 expression presented better OS and post-progression survival. This beneficial effect was particularly evident in patients with adenocarcinoma and during the early stages of NSCLC. Decreased expression of HSD17B2 appears to be a frequent feature in NSCLC. Retrospective analysis suggests that the HSD17B2 mRNA and protein status might be independent prognostic factors in NSCLC and should be further investigated.

Retinoic Acids in the Treatment of Most Lethal Solid Cancers

Although the use of oral administration of pharmacological all-trans retinoic acid (ATRA) concentration in acute promyelocytic leukaemia (APL) patients was approved for over 20 years and used as standard therapy still to date, the same use in solid cancers is still controversial. In the present review the literature about the top five lethal solid cancers (lung, stomach, liver, breast, and colon cancer), as defined by The Global Cancer Observatory of World Health Organization, and retinoic acids (ATRA, 9-cis retinoic acid, and 13-cis retinoic acid, RA) was compared. The action of retinoic acids in inhibiting the cell proliferation was found in several cell pathways and compartments: from membrane and cytoplasmic signaling, to metabolic enzymes, to gene expression. However, in parallel in the most aggressive phenotypes several escape routes have evolved conferring retinoic acids-resistance. The comparison between different solid cancer types pointed out that for some cancer types several information are still lacking. Moreover, even though some pathways and escape routes are the same between the cancer types, sometimes they can differently respond to retinoic acid therapy, so that generalization cannot be made. Further studies on molecular pathways are needed to perform combinatorial trials that allow overcoming retinoic acids resistance.

The Impact of Estrogen in the Tumor Microenvironment

Tumor immune escape is now a hallmark of cancer development, and therapies targeting these pathways have emerged as standard of care. Specifically, immune checkpoint signal blockade offers durable responses and increased overall survival. However, the majority of cancer patients still do not respond to checkpoint blockade immune therapy leading to an unmet need in tumor immunology research. Sex-based differences have been noted in the use of cancer immunotherapy suggesting that sex hormones such as estrogen may play an important role in tumor immune regulation. Estrogen signaling already has a known role in autoimmunity, and the estrogen receptor can be expressed across multiple immune cell populations and effect their regulation. While it has been well established that tumor cells such as ovarian carcinoma, breast carcinoma, and even lung carcinoma can be regulated by estrogen, research into the role of estrogen in the regulation of tumor-associated immune cells is still emerging. In this chapter, we discuss the role of estrogen in the tumor immune microenvironment and the possible immunotherapeutic implications of targeting estrogen in cancer patients.

Expression of female sex hormone receptors and its relation to clinicopathological characteristics and prognosis of lung adenocarcinoma

Background

Adenocarcinoma (ADC) of the lung exhibits different clinicopathological characteristics in men and women. Recent studies have suggested that these differences originate from the expression of female sex hormone receptors in tumor cells. The aim of the present study was to evaluate the immunohistochemical expression of female sex hormone receptors in lung ADC and determine the expression patterns in patients with different clinicopathological characteristics.

Methods

A total of 84 patients with lung ADC who underwent surgical resection and/or core biopsy were recruited for the present study. Immunohistochemical staining was performed for estrogen receptor α (ERα), estrogen receptor β (ERβ), progesterone receptor (PR), epidermal growth factor receptor (EGFR), EGFR E746-A750 del, and EGFR L858R using tissue microarray.

Results

A total of 39 (46.4%) ERα-positive, 71 (84.5%) ERβ-positive, and 46 (54.8%) PR-positive lung ADCs were identified. In addition, there were 81 (96.4%) EGFR-positive, 14 (16.7%) EGFR E746-A750 del–positive, and 34 (40.5%) EGFR L858R–positive cases. The expression of female sex hormone receptors was not significantly different in clinicopathologically different subsets of lung ADC.

Conclusions

Expression of female sex hormone receptors is not associated with the prognosis and clinicopathological characteristics of patients with lung ADC.

The influence of hormone replacement therapy on lung cancer incidence and mortality

OBJECTIVE

Data regarding the effects of hormone replacement therapy (HRT) on non-small cell lung cancer (NSCLC) are mixed. We hypothesized HRT would have a protective benefit with reduced NSCLC incidence among women in a large, prospective cohort.

METHODS

We used data from the multicenter randomized Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (1993-2001). Participants were women aged 50 to 74 years followed prospectively for up to 13 years for cancer screening. The influence of HRT on the primary outcome of NSCLC incidence and secondary outcomes of all-cause and disease-specific mortality were assessed with Kaplan-Meier analysis and Cox proportional hazard models adjusting for covariates.

RESULTS

In the overall cohort of 75,587 women, 1147 women developed NSCLC after a median follow-up of 11.5 years. HRT use was characterized as 49.4% current users, 17.0% former users, and 33.6% never users. Increased age, smoking, comorbidities, and family history were associated with increased risk of NSCLC. On multivariable analysis, current HRT use was associated with reduced risk of NSCLC compared with never users (hazard ratio, 0.80; 95% confidence interval, 0.70-0.93; P = .009). HRT or oral contraception use was not associated with significant differences in all-cause mortality or disease-specific mortality.

CONCLUSIONS

These data represent among the largest prospective cohorts suggesting HRT use may have a protective effect on the development of NSCLC among women; the physiological basis of this effect merits further study; however, the results may influence discussion surrounding HRT use in women.

Clinical characteristics and survival in non-small cell lung cancer patients by smoking history: a population-based cohort study

Introduction: Approximately, 10-15% of lung cancer patients have never smoked. Previous epidemiological studies on non-tobacco associated lung cancer have been hampered by selected data from a small number of hospitals or limited numbers of patients. By use of data from large population-based registers with national coverage, this study aims to compare characteristics and survival of patients with non-small cell lung cancer (NSCLC) with different smoking histories.Methods: Swedish national population-based registers were used to retrieve data on patients diagnosed with primary NSCLC between 2002 and 2016. The Kaplan-Meier method and Cox proportional hazard models were used to estimate overall survival and lung cancer-specific survival by smoking history.Results: In total, 41,262 patients with NSCLC were included. Of those, 4624 (11%) had never smoked. Never-smokers were more often women and older compared to ever smokers (current and former). Adenocarcinoma was proportionally more common in never-smokers (77%) compared to current (52%) and former smokers (57%). Stage IV disease was more common in never-smokers (57%) than in current (48%) and former smokers (48%). Epidermal growth factor receptor mutation was observed more in never-smokers (37%) compared to current (5%) and former smokers (9%). Both lung cancer-specific and overall survival were higher for never-smokers compared to current smokers.Conclusions: The observed differences in characteristics between never-smokers and smokers, and the higher survival in never-smokers compared to smokers from this large population-based study provide further evidence that lung cancer in never-smokers is clinically different to tobacco-associated lung cancer. The findings from this study emphasise the need for an improved understanding of genetics, pathogenesis, mechanisms and progression of non-tobacco associated lung cancer that may help prevent lung cancer or identify individually targeted treatments.

Lung genotoxicity of benzo(a)pyrene in vivo involves reactivation of LINE-1 retrotransposon and early reprogramming of oncogenic regulatory networks

Several lines of evidence have implicated long interspersed nuclear element-1 (LINE-1) retroelement in the onset and progression of lung cancer. Retrotransposition-dependent mechanisms leading to DNA mobilization give rise to insertion mutations and DNA deletions, whereas retrotransposition-independent mechanisms disrupt epithelial programming and differentiation. Previous work by our group established that tobacco carcinogens such as benzo(a)pyrene (BaP) reactivate LINE-1 in bronchial epithelial cells through displacement of nucleosome remodeling and deacetylase (NuRD) corepressor complexes and interference with retinoblastoma-regulated epigenetic signaling. Whether LINE-1 in coordination with other genes within its regulatory network contributes to the in vivo genotoxic response to BaP remains largely unknown. Evidence is presented here that intratracheal instillation of ORFeus^LSL mice with BaP alone or in combination with adenovirus (adeno)-CRE recombinase is genotoxic to the lung and associated with activation of the human LINE-1 transgene present in these mice. LINE-1 reactivation modulated the expression of genes involved in oncogenic signaling, and these responses were most pronounced in female mice compared with males and synergized by adeno-CRE recombinase. This is the first report linking LINE-1 and genes within its oncogenic regulatory network with early sexually dimorphic responses of the lung in vivo.

Sex steroid metabolism and actions in non-small cell lung carcinoma

Despite recent development in targeted therapies, lung cancer still remains the leading cause of cancer death. Therefore, a better understanding of its pathogenesis and progression could contribute to improving the eventual clinical outcome of the patients. Results of recently published several in vitro and clinical studies indicated the possible involvement of sex steroids in both development and progression of non-small cell lung carcinoma (NSCLC). Therefore we summarized the reported clinical relevant information of the sex steroids, their receptors and steroid metabolizing enzymes related to NSCLC in this mini-review. In addition, we also reviewed the potential "endocrine therapy", targeting sex steroid actions and/or metabolism in NSCLC patients.

Role of G Protein-Coupled Estrogen Receptor in Cancer Progression

Cancer is the leading cause of mortality worldwide. In cancer progression, sex hormones and their receptors are thought to be major factors. Many studies have reported the effects of estrogen and estrogen receptors (ERs) in cancer development and progression. Among them, G protein-coupled estrogen receptor (GPER), a G proteincoupled receptor, has been identified as an estrogen membrane receptor unrelated to nuclear ER. The mechanism of GPER, including its biological action, function, and role, has been studied in various cancer types. In this review, we discuss the relation between GPER and estrogen or estrogen agonists/antagonists and cancer progression.

Cytoplasmic ERβ1 expression is associated with survival of patients with Stage IV lung adenocarcinoma and an EGFR mutation at exon 21 L858R subsequent to treatment with EGFR-TKIs

The present study assessed whether estrogen receptor (ER)β1 is associated with the survival of patients with advanced lung adenocarcinoma, with or without mutations of the epidermal growth factor receptor (EGFR) following treatment with EGFR-tyrosine kinase inhibitors (TKIs). Pathologically confirmed stage IV lung adenocarcinomas were assessed for EGFR mutations and ERβ1 expression. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method and the log-rank test. A total of 122 out of the 201 (60.7%) patients had EGFR mutations, 64 (31.8%) of which were EGFR Del19 and 58 mutations (28.9%) were EGFR exon 21 L858R mutation. The presence of EGFR mutations was significantly increased in female patients compared with male patients (P<0.001) and in non-smokers compared with smokers (P<0.001). Patients with EGFR mutations had a significantly improved PFS and OS compared with patients without EGFR mutations treated with EGFR-TKIs. Furthermore, ERβ1 expression was significantly increased in patients with EGFR mutations compared with patients without EGFR mutations (P=0.001). However, the median PFS (P=0.005) and OS (P=0.002) of patients carrying the EGFR exon 21 L858R mutation was significantly decreased in patients with tumors where ERβ1 cytoplasmic expression was high. The multivariate analysis demonstrated that ERβ1 expression was the only independent predictor of PFS (P=0.002) and OS (P=0.003) in patients carrying the EGFR exon 21 L858R mutation. The data demonstrated that ERβ1 expression may predict outcomes of patients with lung adenocarcinoma treated with EGFR-TKI.

Determination and analysis of agonist and antagonist potential of naturally occurring flavonoids for estrogen receptor (ERα) by various parameters and molecular modelling approach

Most estrogen receptor α (ERα) ligands target the ligand binding domain (LBD). Agonist 17β-estradiol (E₂) and tamoxifen (TM, known SERM), bind to the same site within the LBD. However, structures of ligand-bound complexes show that E₂ and TM induce different conformations of helix 12 (H12). During the molecular modelling studies of some naturally occurring flavonoids such as quercetin, luteolin, myricetin, kaempferol, naringin, hesperidin, galangin, baicalein and epicatechin with human ERα (3ERT and 1GWR), we observed that most of the ligands bound to the active site pocket of both 3ERT and 1GWR. The docking scores, interaction analyses, and conformation of H12 provided the data to support for the estrogenic or antiestrogenic potential of these flavonoids to a limited degree. Explicit molecular dynamics for 50 ns was performed to identify the stability and compatibility pattern of protein-ligand complex and RMSD were obtained. Baicalein, epicatechin, and kaempferol with 1GWR complex showed similar RMSD trend with minor deviations in the protein backbone RMSD against 1GWR-E₂ complex that provided clear indications that ligands were stable throughout the explicit molecular simulations in the protein and outcome of naringin-3ERT complex had an upward trend but stable throughout the simulations and all molecular dynamics showed stability with less than overall 1 Å deviation throughout the simulations. To examine their estrogenic or antiestrogenic potential, we studied the effect of the flavonoids on viability, progesterone receptor expression and 3xERE/3XERRE-driven reporter gene expression in ERα positive and estrogen responsive MCF-7 breast cancer cells. Epicatechin, myricetin, and kaempferol showed estrogenic potential at 5 µM concentration.

Heterogeneous tumor features and treatment outcome between males and females with lung cancer (LC): Do gender and sex matter?

Lung cancer (LC) is the leading cause of cancer-related death worldwide, despite a decreasing incidence rate in recent years, especially in men. Most risk factors for LC could be linked to an individual's reproductive system and secondary sex characteristics ('sex-related') and/or to some physical, behavioral and personality traits ('gender-related') peculiar to males rather than females or vice versa. An imbalance of these etiologic factors could explain why some LC features may differ between sexes. For this review, an extended literature data collection was performed, using keywords to identify 'sex/gender' and 'LC'. Differences between genders in LC epidemiology, pathological and molecular characteristics, loco-regional and/or systemic treatments outcome and prognosis were systematically analyzed. The possible predictive role of physio-pathological factors in males and females paves the way for a personalized therapeutic approach, emphasizing the need to include gender as a stratification factor in future clinical trials design.

Hormone Replacement Therapy in Cancer Survivors - Review of the Literature

Rapid advance in oncology leads to increasing survival of oncologic patients. More and more of them live long enough to reach either the natural age of menopause or, as a side effect of their oncotherapy, experience the cessation of gonadal function, leading to premature ovarian insufficiency, with disturbing vasomotor symtoms and long-term negative cardiovascular and skeletal effects. Thus, an ever increasing number of cancer survivors search endocrinologic help in the form of hormone replacement therapy (HRT). The misinterpretation of the WHI (Women's Health Initiative) Study has lead to an irrational fear of female hormone replacement, both by the general population and medical professionals. It has seemed the logical and safe conclusion to many physicians to avoid HRT, supposing that this attitude definitely causes no harm, whereas the decision of prescribing estrogen alone or with progestins might bear oncologic and thromboembolic risks and may even lead to litigation in case of a potentially related complication. However, it was known even before the WHI results that premature menopause and hypogonadism decreases the life expectancy of women by years through its skeletal and cardiovascular effects, and this negative effect correlates with the length of the hypoestrogenaemic period. Therefore, the denial of HRT also needs to be supported by evidence and should be weighed againts the risks of HRT. Yet, the oncologic risk of HRT is extremely difficult to assess. In this work we review the latest evidence from in vitro experiments to clinical studies, regarding HRT in survivors of gynecologic and non-gynecologic cancers. Based on our literature research, we group tumours regarding the oncologic risk of properly chosen female hormone replacement therapy in cancer survivors as follows: ’HRT is advanageous’ (e.g. endometrial cancer type I, cervical adenocarcinoma, haematologic malignancies, local cutaneous malignant melanoma, colorectal cancer, hepatocellular cancer); ’HRT is neutral’ (e.g. BRCA 1/2 mutation carriers without cancer, endometrial cancer type II, uterinal carcinosarcoma and adenosarcoma, certain types of ovarian cancer, cervical, vaginal and vulvar squamous cell carcinoma, prolactinoma, kidney cancer, pancreatic cancer, thyroid cancer); ’HRT is relatively contraindicated’ for various reasons (e.g. leiomyosarcoma, certain types of ovarian tumours, brain tumours, advanced metastatic malignant melanoma, lung cancer, gastric cancer, bladder cancer); ’HRT is diasadvantageous and thus contraindicated’ (e.g. breast cancer, endometrial stroma sarcoma, meningioma, glioma, hormone receptor positive gastric and bladder cancer).

G Protein-Coupled Estrogen Receptor: A Potential Therapeutic Target in Cancer

The G protein-coupled estrogen receptor (GPER) is a seven-transmembrane-domain receptor that mediates non-genomic estrogen related signaling. After ligand activation, GPER triggers multiple downstream pathways that exert diverse biological effects on the regulation of cell growth, migration and programmed cell death in a variety of tissues. A significant correlation between GPER and the progression of multiple cancers has likewise been reported. Therefore, a better understanding of the role GPER plays in cancer biology may lead to the identification of novel therapeutic targets, especially among estrogen-related cancers. Here, we review cell signaling and detail the functions of GPER in malignancies.

Nut and peanut butter consumption and the risk of lung cancer and its subtypes: A prospective cohort study

OBJECTIVES

Nut consumption has been associated with reduced cancer-related mortality, but evidence for a relation between nut intake and lung cancer risk is limited. We investigated the association between total nut, tree nut, peanut, and peanut butter intake and the risk of lung cancer and its subtypes in the Netherlands Cohort Study.

MATERIALS AND METHODS

In 1986, dietary and lifestyle habits of 120,852 participants, aged 55-69 years, were measured with a questionnaire. After 20.3 years of follow-up, 3720 subcohort members and 2861 lung cancer cases were included in multivariable case-cohort analyses.

RESULTS

Total nut intake was not significantly associated with total lung cancer risk in men or women. For small cell carcinoma, a significant inverse association with total nut intake was observed in men after controlling for detailed smoking habits (HR (95%CI) for 10+ g/day vs. nonconsumers: 0.62 (0.43-0.89), p-trend: 0.024). Inverse relations with small cell carcinoma were also found for tree nut and peanut intake in men in continuous analyses (HR (95%CI) per 5 g/day increment: 0.70 (0.53-0.93) and 0.93 (0.88-0.98), respectively). For the other lung cancer subtypes, no significant associations were seen in men. Nut intake was not related to the risk of lung cancer subtypes in women, and no associations were found for peanut butter in both sexes.

CONCLUSION

Increased nut intake might contribute to the prevention of small cell carcinoma in men. No significant associations were found in men for the other subtypes or total lung cancer, in women, or for peanut butter intake.

Pregnenolone as a potential candidate for hormone therapy for female reproductive disorders targeting ERβ

Many steroid hormones such as estrogen (E2) bind to their receptors for the regulation of biological processes. Pregnenolone (P5) is the precursor form of almost all steroid hormones and is often used to treat skin disorders and neurological complications. However, the mechanism and physiological function of P5 in reproductive organs are not well established. In this study, we investigated the effects of P5 on activation and expression of E2 receptor (ER) in the uteri and ovaries. To study the mechanism of P5 directly, Ishikawa cells were transfected with E2 response element (ERE)-luciferase plasmid and isoforms of ER. ERE-luciferase activity induced by P5 was similar to that induced by E2, and P5 showed high activity for ERβ without any relevance to P5-metabolizing hormones such as progesterone (P4) and E2. In an animal study, immature female rats treated with P5 showed upregulation of ERα and downregulation of ERβ in the uteri, which is the main organ expressing ERα. In ERβ-expressing organ ovaries, estrogen receptor 1, estrogen receptor 2, and P4 receptor were all downregulated by P5 and E2. Also, a decrease of ovarian cell proliferation and viability was observed in response to P5 relative to the control, suggesting that P5 may be a candidate for antiproliferative hormone of ovarian cancer. These findings suggest that P5 stimulates ERE promoter by ERβ-mediated signaling in the uteri and ovaries. Activation of ERβ by P5 may help in understanding the mechanism of ER-related female reproductive diseases such as endometriosis and ovarian cancer.

Estrogen Receptor Signaling in Radiotherapy: From Molecular Mechanisms to Clinical Studies

Numerous studies have established a proof of concept that abnormal expression and function of estrogen receptors (ER) are crucial processes in initiation and development of hormone-related cancers and also affect the efficacy of anti-cancer therapy. Radiotherapy has been applied as one of the most common and potent therapeutic strategies, which is synergistic with surgical excision, chemotherapy and targeted therapy for treating malignant tumors. However, the impact of ionizing radiation on ER expression and ER-related signaling in cancer tissue, as well as the interaction between endocrine and irradiation therapy remains largely elusive. This review will discuss recent findings on ER and ER-related signaling, which are relevant for cancer radiotherapy. In addition, we will summarize pre-clinical and clinical studies that evaluate the consequences of anti-estrogen and irradiation therapy in cancer, including emerging studies on head and neck cancer, which might improve the understanding and development of novel therapeutic strategies for estrogen-related cancers.

The Role of the Estrogen Pathway in the Tumor Microenvironment

Estrogen receptors are broadly expressed in many cell types involved in the innate and adaptive immune responses, and differentially regulate the production of cytokines. While both genomic and non-genomic tumor cell promoting mechanisms of estrogen signaling are well characterized in multiple carcinomas including breast, ovarian, and lung, recent investigations have identified a potential immune regulatory role of estrogens in the tumor microenvironment. Tumor immune tolerance is a well-established mediator of oncogenesis, with increasing evidence indicating the importance of the immune response in tumor progression. Immune-based therapies such as antibodies that block checkpoint signals have emerged as exciting therapeutic approaches for cancer treatment, offering durable remissions and prolonged survival. However, only a subset of patients demonstrate clinical response to these agents, prompting efforts to elucidate additional immunosuppressive mechanisms within the tumor microenvironment. Evidence drawn from multiple cancer types, including carcinomas traditionally classified as non-immunogenic, implicate estrogen as a potential mediator of immunosuppression through modulation of protumor responses independent of direct activity on tumor cells. Herein, we review the interplay between estrogen and the tumor microenvironment and the clinical implications of endocrine therapy as a novel treatment strategy within immuno-oncology.