Estrogen regulated proteases and antiproteases in ovarian and breast cancer cells

Sex differences in airway disease: estrogen and airway surface liquid dynamics

Biological sex differences exist for many airway diseases in which females have either worse or better health outcomes. Inflammatory airway diseases such as cystic fibrosis (CF) and asthma display a clear male advantage in post-puberty while a female benefit is observed in asthma during the pre-puberty years. The influence of menstrual cycle stage and pregnancy on the frequency and severity of pulmonary exacerbations in CF and asthma point to a role for sex steroid hormones, particularly estrogen, in underpinning biological sex differences in these diseases. There are many ways by which estrogen may aggravate asthma and CF involving disturbances in airway surface liquid (ASL) dynamics, inappropriate hyper-immune and allergenic responses, as well as exacerbation of pathogen virulence. The deleterious effect of estrogen on pulmonary function in CF and asthma contrasts with the female advantage observed in airway diseases characterised by pulmonary edema such as pneumonia, acute respiratory distress syndrome (ARDS) and COVID-19. Airway surface liquid hypersecretion and alveolar flooding are hallmarks of ARDS and COVID-19, and contribute to the morbidity and mortality of severe forms of these diseases. ASL dynamics encompasses the intrinsic features of the thin lining of fluid covering the airway epithelium which regulate mucociliary clearance (ciliary beat, ASL height, volume, pH, viscosity, mucins, and channel activating proteases) in addition to innate defence mechanisms (pathogen virulence, cytokines, defensins, specialised pro-resolution lipid mediators, and metabolism). Estrogen regulation of ASL dynamics contributing to biological sex differences in CF, asthma and COVID-19 is a major focus of this review.

Endometriosis-Associated Macrophages: Origin, Phenotype, and Function

Endometriosis is a complex, heterogeneous, chronic inflammatory condition impacting ~176 million women worldwide. It is associated with chronic pelvic pain, infertility, and fatigue, and has a substantial impact on health-related quality of life. Endometriosis is defined by the growth of endometrial-like tissue outside the uterus, typically on the lining of the pelvic cavity and ovaries (known as "lesions"). Macrophages are complex cells at the center of this enigmatic condition; they are critical for the growth, development, vascularization, and innervation of lesions as well as generation of pain symptoms. In health, tissue-resident macrophages are seeded during early embryonic life are vital for development and homeostasis of tissues. In the adult, under inflammatory challenge, monocytes are recruited from the blood and differentiate into macrophages in tissues where they fulfill functions, such as fighting infection and repairing wounds. The interplay between tissue-resident and recruited macrophages is now at the forefront of macrophage research due to their differential roles in inflammatory disorders. In some cancers, tumor-associated macrophages (TAMs) are comprised of tissue-resident macrophages and recruited inflammatory monocytes that differentiate into macrophages within the tumor. These macrophages of different origins play differential roles in disease progression. Herein, we review the complexities of macrophage dynamics in health and disease and explore the paradigm that under disease-modified conditions, macrophages that normally maintain homeostasis become modified such that they promote disease. We also interrogate the evidence to support the existence of multiple phenotypic populations and origins of macrophages in endometriosis and how this could be exploited for therapy.

The estrogen-macrophage interplay in the homeostasis of the female reproductive tract

BACKGROUND

Estrogens are known to orchestrate reproductive events and to regulate the immune system during infections and following tissue damage. Recent findings suggest that, in the absence of any danger signal, estrogens trigger the physiological expansion and functional specialization of macrophages, which are immune cells that populate the female reproductive tract (FRT) and are increasingly being recognized to participate in tissue homeostasis beyond their immune activity against infections. Although estrogens are the only female gonadal hormones that directly target macrophages, a comprehensive view of this endocrine-immune communication and its involvement in the FRT is still missing.

OBJECTIVE AND RATIONALE

Recent accomplishments encourage a revision of the literature on the ability of macrophages to respond to estrogens and induce tissue-specific functions required for reproductive events, with the aim to envision macrophages as key players in FRT homeostasis and mediators of the regenerative and trophic actions of estrogens.

SEARCH METHODS

We conducted a systematic search using PubMed and Ovid for human, animal (rodents) and cellular studies published until 2018 on estrogen action in macrophages and the activity of these cells in the FRT.

OUTCOMES

Our search identified the remarkable ability of macrophages to activate biochemical processes in response to estrogens in cell culture experiments. The distribution at specific locations, interaction with selected cells and acquisition of distinct phenotypes of macrophages in the FRT, as well as the cyclic renewal of these properties at each ovarian cycle, demonstrate the involvement of these cells in the homeostasis of reproductive events. Moreover, current evidence suggests an association between estrogen-macrophage signaling and the generation of a tolerant and regenerative environment in the FRT, although a causative link is still missing.

WIDER IMPLICATIONS

Dysregulation of the functions and estrogen responsiveness of FRT macrophages may be involved in infertility and estrogen- and macrophage-dependent gynecological diseases, such as ovarian cancer and endometriosis. Thus, more research is needed on the physiology and pharmacological control of this endocrine-immune interplay.

PBOV1 correlates with progression of ovarian cancer and inhibits proliferation of ovarian cancer cells

Prostate and breast cancer overexpressed 1 (PBOV1) is significantly upregulated in prostate, breast and bladder cancer, while its expression status in ovarian cancer and its clinical significance are unclear. We examined the expression levels of PBOV1 mRNA and protein in ovarian cancer cell lines and primary tissues using real-time PCR and western blotting. Immunohistochemistry was employed to analyze PBOV1 expression in 17 normal ovaries, 13 cystadenoma tissues, 14 borderline tumor tissues, and 165 clinicopathologically characterized ovarian cancers. There was negative PBOV1 expression in the 17 normal ovarian epithelial tissues. Compared to the normal ovarian epithelial cells, PBOV1 mRNA and protein were overexpressed in ovarian cancer cell lines. There was high PBOV1 protein expression in the ovarian cancer tissues from 59 of the 165 (35.8%) patients; PBOV1 expression was weak in 106 (64.2%) patients. Notably, there were significant negative associations between high PBOV1 expression and ascending histological grade, late pT/pN/pM, and International Federation of Gynecology and Obstetrics (FIGO) stage (P<0.05). Patients with high PBOV1 expression had longer overall survival; patients with low PBOV1 expression had shorter survival. Multivariate analysis revealed that PBOV1 upregulation is an independent prognostic indicator for ovarian cancer and might serve as a tumor-suppressor gene. Furthermore, PBOV1 overexpression inhibited ovarian cancer cell proliferation and tumorigenesis in vitro and in a tumor transplantation nude mouse model. In conclusion, our results suggest that PBOV1 may play an important role in suppressing ovarian cancer proliferation and carcinogenesis. PBOV1 may be a novel and useful prognostic marker and potential target for treating human ovarian cancer.

MAPK Activation Predicts Poor Outcome and the MEK Inhibitor, Selumetinib, Reverses Antiestrogen Resistance in ER-Positive High-Grade Serous Ovarian Cancer

PURPOSE

Although 67% of high-grade serous ovarian cancers (HGSOC) express the estrogen receptor (ER), most fail antiestrogen therapy. Because MAPK activation is frequent in ovarian cancer, we investigated if estrogen regulates MAPK and if MEK inhibition (MEKi) reverses antiestrogen resistance.

EXPERIMENTAL DESIGN

Effects of MEKi (selumetinib), antiestrogen (fulvestrant), or both were assayed in ER-positive HGSOC in vitro and in xenografts. Response biomarkers were investigated by gene expression microarray and reverse phase protein array (RPPA). Genes differentially expressed in two independent primary HGSOC datasets with high versus low pMAPK by RPPA were used to generate a "MAPK-activated gene signature." Gene signature components that were reversed by MEKi were then identified.

RESULTS

High intratumor pMAPK independently predicts decreased survival (HR, 1.7; CI > 95%,1.3-2.2; P = 0.0009) in 408 HGSOC from The Cancer Genome Atlas. A differentially expressed "MAPK-activated" gene subset was also prognostic. "MAPK-activated genes" in HGSOC differ from those in breast cancer. Combined MEK and ER blockade showed greater antitumor effects in xenografts than monotherapy. Gene set enrichment analysis and RPPA showed that dual therapy downregulated DNA replication and cell-cycle drivers, and upregulated lysosomal gene sets. Selumetinib reversed expression of a subset of "MAPK-activated genes" in vitro and/or in xenografts. Three of these genes were prognostic for poor survival (P = 0.000265) and warrant testing as a signature predictive of MEKi response.

CONCLUSIONS

High pMAPK is independently prognostic and may underlie antiestrogen failure. Data support further evaluation of fulvestrant and selumetinib in ER-positive HGSOC. The MAPK-activated HGSOC signature may help identify MEK inhibitor responsive tumors.

Effects of oestrogen on long noncoding RNA expression in oestrogen receptor alpha-positive ovarian cancer cells

Although oestrogen (E2) signalling has long been implicated in epithelial ovarian cancer (EOC) progression, the underlying mechanisms remain unknown. Long noncoding RNAs (lncRNAs) play a major role in cancer progression; therefore, our aim was to explore whether any lncRNA is regulated by E2 and plays some potential roles in the hormonal regulation of EOC progression. Here, we reported that E2 significantly dysregulated 115 lncRNAs (fold change ≥1.5, P<0.05) in E2 receptor (ER) alpha (ERα)-positive EOC SKOV3 cells compared with E2-untreated controls based on the microarray analysis. E2 regulation of the expression of 58 lncRNAs was bioinformatics predicted to be ERα-mediated; this was confirmed for two candidates. Both TC0101441 and TC0101686 were dysregulated by E2 in another ERα-positive PEO1 cells but not in ERα-negative A2780 cells. Additionally, the modulation of TC0101441 and TC0101686 expression by E2 was abrogated by the ER inhibitor ICI 182, 780 and short hairpin RNAs targeting ERα (ERα-shRNA). Further study of the two lncRNA expression indicated that ERα-positive EOC tissues had lower expression of TC0101686 and higher expression of TC0101441 compared to ERα-negative tissues. Particularly, elevated TC0101441 expression was correlated with lymph node metastasis, showing a metastatic potential. Results of in vitro assays further confirmed the pro-metastatic effect of TC0101441 and revealed that knockdown of TC0101441 also impaired E2-induced EOC cell migration/invasion by at least partly, regulating MMP2 and MMP3. Together, our findings demonstrate, for the first time, that E2 modulates lncRNA expression in ERα-positive EOC cells and that this regulation is sometimes ERα-mediated. Furthermore, our findings reveal that TC0101441contributes to E2-induced EOC cell migration/invasion. These results may shed a new insight into estrogenic effect on EOC progression by providing a perspective of lncRNA.

Expression and clinical significance of estrogen-regulated long non-coding RNAs in estrogen receptor α-positive ovarian cancer progression

Estrogen (E2) has long been implicated in epithelial ovarian cancer (EOC) progression. The effects of E2 on cancer progression can be mediated by numerous target genes, including coding RNAs and, more recently, non-coding RNAs (ncRNAs). Among the ncRNAs, long ncRNAs (lncRNAs) have emerged as new regulators in cancer progression; therefore, our aim was to determine whether the expression of any lncRNAs is regulated by E2 and, if so, whether a subset of these lncRNAs have some clinical significance in EOC progression. A microarray was performed to identify E2-regulated lncRNAs in E2 receptor (ER) α-positive EOC cells. Bioinformatics analyses of lncRNAs were conducted, focusing on gene ontology and pathway analyses. Quantitative real-time polymerase chain reactions were performed to confirm the expression of certain lncRNAs in ERα-positive EOC tissues. The correlation between certain lncRNA expression and clinicopathological factors as well as prognosis in ERα-positive EOC patients was then analyzed. We showed that 115 lncRNAs exhibited significant changes in E2-treated SKOV3 cells compared with untreated controls. Most of these lncRNAs were predicated to have potential to contribute to cancer progression. Notably, three candidates (TC0100223, TC0101686 and TC0101441) were aberrantly expressed in ERα-positive compared to ERα-negative EOC tissues, showing correlations with some malignant cancer phenotypes such as advanced FIGO stage and/or high histological grade. Furthermore, multivariate analysis indicated that TC0101441 was an independent prognostic factor for overall survival. Taken together, these results indicate for the first time that E2 can modulate lncRNA expression in ERα-positive EOC cells and that certain lncRNAs are correlated with advanced cancer progression and suggestive of a prognostic indicator in ERα-positive EOC patients. Knowledge of these E2-regulated lncRNAs could aid in the future understanding of the estrogenic effect on EOC progression and may assist in the clinical design of new target therapies based on a perspective of lncRNA.

New insights on the role of hormonal therapy in ovarian cancer

Ovarian cancer (OVCA) is the most lethal gynecological malignancy. It is often diagnosed in advanced stages and despite therapy, 70% relapse within 2years with incurable disease. Regimens with clinical benefit and minimal toxicity are urgently needed. More effective hormonal therapies would be appealing in this setting. Estrogens (E2) are implicated in the etiology of OVCA. Estrogens drive proliferation and anti-estrogens inhibit ovarian cancer growth in vitro and in vivo. Despite estrogen receptor (ER) expression in 67% of OVCAs, small anti-estrogen therapy trials have been disappointing and the benefit of hormonal therapy has not been systematically studied in large well-designed trials. OVCAs often manifest de novo anti-estrogen resistance and those that initially respond invariably develop resistance. Estrogens stimulate ovarian cancer progression by transcriptional activation and cross talk between liganded ER and mitogenic pathways, both of which drive cell cycle progression. Estrogen deprivation and estrogen receptor (ER) blockade cause cell cycle arrest in susceptible OVCAs by increasing the cell cycle inhibitor, p27. This review summarizes and discusses scientific and epidemiological evidence supporting estrogen's role in ovarian carcinogenesis, provides an overview of clinical trials of ER blockade and aromatase inhibitors in OVCA and reviews potential causes of antiestrogen resistance. Anti-estrogen resistance was recently shown to be reversed by dual ER and Src signaling blockade. Blocking cross-talk between ER and constitutively activated kinase pathways may improve anti-estrogen therapeutic efficacy in OVCA, as has been demonstrated in other cancers. Novel strategies to improve benefit from anti-estrogens by combining them with targeted therapies are reviewed.

Hormone response in ovarian cancer: time to reconsider as a clinical target?

Ovarian cancer is the sixth most common cancer worldwide among women in developed countries and the most lethal of all gynecologic malignancies. There is a critical need for the introduction of targeted therapies to improve outcome. Epidemiological evidence suggests a critical role for steroid hormones in ovarian tumorigenesis. There is also increasing evidence from in vitro studies that estrogen, progestin, and androgen regulate proliferation and invasion of epithelial ovarian cancer cells. Limited clinical trials have shown modest response rates; however, they have consistently identified a small subset of patients that respond very well to endocrine therapy with few side effects. We propose that it is timely to perform additional well-designed trials that should include biomarkers of response.

Requirement for stromal estrogen receptor alpha in cervical neoplasia

The major etiological factor for cervical cancer is the high-risk human papillomavirus (HPV), which encodes E6 and E7 oncogenes. However, HPV is not sufficient, and estrogen has been proposed as an etiological cofactor for the disease. Its requirement has been demonstrated in mouse models for HPV-associated cervical cancer (e.g., K14E7 transgenic mice). Although germline knockout of estrogen receptor alpha (ERα) renders mice resistant to cervical cancer, the cell-type-specific requirement for ERα is not known. In this study, we demonstrate that temporal deletion of stromal ERα induced complete regression of cervical dysplasia in K14E7 mice. Our results strongly support the hypothesis that stromal ERα is necessary for HPV-induced cervical carcinogenesis and implicate paracrine mechanisms involving ERα signaling in the development of estrogen-dependent cervical cancers. This is the first evidence to support the importance of stromal ERα in estrogen-dependent neoplastic disease of the female reproductive tract.

Hormone response in ovarian cancer: time to reconsider as a clinical target?

Ovarian cancer is the sixth most common cancer worldwide among women in developed countries and the most lethal of all gynecologic malignancies. There is a critical need for the introduction of targeted therapies to improve outcome. Epidemiological evidence suggests a critical role for steroid hormones in ovarian tumorigenesis. There is also increasing evidence from in vitro studies that estrogen, progestin, and androgen regulate proliferation and invasion of epithelial ovarian cancer cells. Limited clinical trials have shown modest response rates; however, they have consistently identified a small subset of patients that respond very well to endocrine therapy with few side effects. We propose that it is timely to perform additional well-designed trials that should include biomarkers of response.

Oestrogen receptor α mediates 17β-estradiol enhancement of ovarian cancer cell motility through up-regulation of survivin expression

OBJECTIVE

To determine the role of oestrogen receptor α (ERα) in the regulation of survivin expression by 17β-estradiol (E(2)) in ovarian cancer cells and to evaluate the mechanism of E(2) action on ovarian cancer cell migration.

METHODS

We performed RT-PCR and Western blot analysis to assess the expression of ERα in the ovarian cancer cell lines NIH:OVCAR-3 and SKOV-3. Full-length ERα cDNA was reintroduced into SKOV-3 cells through stable transfection. After treatment with E(2), with or without pre-incubation of anti-oestrogen compound ICI 182780, RT-PCR and Western blot analysis were performed to detect survivin expression at the mRNA and protein levels. RNA interference (RNAi) was used to inhibit the expression of survivin in SKOV-3 cells. Wound healing-induced migration and Matrigel invasion experiments were performed to determine the motility of ovarian cancer cells. RT-PCR and gelatin zymography were used to detect the expression and activity of MMP-9 in SKOV-3 cells.

RESULTS

A stably transfected clone with over-expression of ERα, SKOV-α, was isolated. Exogenous or endogenous expression of ERα in SKOV-3 or NIH:OVCAR-3 cells resulted in a significant up-regulation of survivin in the presence of E(2). Pre-treatment with ICI 182780 attenuated the up-regulation of survivin by E(2). Previous data from our laboratory showed that E(2) enhanced the motility of ovarian cancer cells. RNAi strongly inhibited survivin expression in SKOV-3 cells. Knock-down of survivin expression reduced the migration and invasion of SKOV-3 cells, which correlated with down-regulation of MMP9 mRNA expression and activity.

CONCLUSIONS

ERα may be responsible for the up-regulation of survivin after E(2) treatment in ovarian cancer cells. The mechanism of oestrogen-promoted ovarian cancer metastasis may due to the up-regulation of survivin conducted through the ERα signalling pathway.

N-terminal prolactin-derived fragments, vasoinhibins, are proapoptoptic and antiproliferative in the anterior pituitary

The anterior pituitary is under a constant cell turnover modulated by gonadal steroids. In the rat, an increase in the rate of apoptosis occurs at proestrus whereas a peak of proliferation takes place at estrus. At proestrus, concomitant with the maximum rate of apoptosis, a peak in circulating levels of prolactin is observed. Prolactin can be cleaved to different N-terminal fragments, vasoinhibins, which are proapoptotic and antiproliferative factors for endothelial cells. It was reported that a 16 kDa vasoinhibin is produced in the rat anterior pituitary by cathepsin D. In the present study we investigated the anterior pituitary production of N-terminal prolactin-derived fragments along the estrous cycle and the involvement of estrogens in this process. In addition, we studied the effects of a recombinant vasoinhibin, 16 kDa prolactin, on anterior pituitary apoptosis and proliferation. We observed by Western Blot that N-terminal prolactin-derived fragments production in the anterior pituitary was higher at proestrus with respect to diestrus and that the content and release of these prolactin forms from anterior pituitary cells in culture were increased by estradiol. A recombinant preparation of 16 kDa prolactin induced apoptosis (determined by TUNEL assay and flow cytometry) of cultured anterior pituitary cells and lactotropes from ovariectomized rats only in the presence of estradiol, as previously reported for other proapoptotic factors in the anterior pituitary. In addition, 16 kDa prolactin decreased forskolin-induced proliferation (evaluated by BrdU incorporation) of rat total anterior pituitary cells and lactotropes in culture and decreased the proportion of cells in S-phase of the cell cycle (determined by flow cytometry). In conclusion, our study indicates that the anterior pituitary production of 16 kDa prolactin is variable along the estrous cycle and increased by estrogens. The antiproliferative and estradiol-dependent proapoptotic actions of this vasoinhibin may be involved in the control of anterior pituitary cell renewal.

Acid treatment of melanoma cells selects for invasive phenotypes

Solid tumors become acidic due to hypoxia and upregulated glycolysis. We have hypothesized that this acidosis leads to more aggressive invasive behavior during carcinogenesis (Nature Reviews Cancer 4:891-899, 2004). Previous work on this subject has shown mixed results. While some have observed an induction of metastasis and invasion with acid treatments, others have not. To investigate this, human melanoma cells were acclimated to low pH growth conditions. Significant cell mortality occurred during acclimation, suggesting that acidosis selected for resistant phenotypes. Cells maintained under acidic conditions exhibited a greater range of motility, a reduced capacity to form flank tumors in SCID mice and did not invade more rapidly in vitro, compared to non-selected control cells. However, re-acclimation of these selected cells to physiological pH gave rise to stable populations with significantly higher in vitro invasion. These re-acclimated cells maintained higher invasion and higher motility for multiple generations. Transcriptomic analyses of these three phenotypes revealed significant differences, including upregulation of relevant pathways important for tissue remodeling, cell cycle control and proliferation. These results reinforce the hypothesis that acidosis promotes selection of stable, more invasive phenotypes, rather than inductive changes, which would be reversible.

A Significant Correlation between Nuclear CXCR4 Expression and Axillary Lymph Node Metastasis in Hormonal Receptor Negative Breast Cancer

BACKGROUND AND OBJECTIVES

In breast cancer, the expression pattern of CXCR4 may be correlated with the degree of axillary lymph node involvement. The aim of this study was to evaluate the contributing factors that contribute to the correlation between CXCR4 expression and axillary lymph node metastasis in breast cancer.

METHODS

Between August 1997 and August 2002, sections of paraffin-embedded tissue were obtained from 107 patients who received optimal treatment for breast cancer. The expression of CXCR4 was evaluated by immunohistochemical staining.

RESULTS

A significant correlation was found in the expression of nuclear CXCR4 and lymph node metastasis (P = 0.03). We found a significant correlation between a high nuclear expression of CXCR4 and axillary lymphatic metastasis in estrogen and progesterone receptor negative breast cancer (P = 0.01 and P = 0.01). There was a significant correlation between the high expression of nuclear CXCR4 and axillary lymphatic metastasis in comparisons between positive estrogen and/or progesterone receptor expression and negative expression (P = 0.02).

CONCLUSIONS

Our results showed that high expression of nuclear CXCR4 was significantly correlated with lymph node metastasis in breast cancer. The high expression of nuclear CXCR4 in hormone receptor negative breast cancer was associated with a high possibility of lymph node metastasis.

A novel dual-target steroid sulfatase inhibitor and antiestrogen: SR 16157, a promising agent for the therapy of breast cancer

Endocrine therapy is the ideal treatment choice for estrogen receptor alpha (ERalpha)-positive breast cancer patients. Principal used therapies target either the ERalpha e.g. by selective ERalpha modulators (SERMs) such as tamoxifen or target estrogen biosynthesis with aromatase inhibitors. Steroid sulfatase (STS) plays a crucial role in formation of compounds with estrogenic properties, converting inactive sulfate-conjugated steroids to active non-conjugated forms. Steroid sulfates are considered as a reservoir for active steroids due to their prolonged half-life and increased concentration in plasma. STS is present in several tissues including the breast, and the STS the mRNA level and enzyme activity is significantly increased in ERalpha-positive breast tumors. Inhibition of STS is therefore a new approach for decreasing estrogenic steroids that stimulate breast cancer. The novel dual-acting compound SR 16157 is designed as a sulfamate-containing STS inhibitor that releases a tissue-selective SERM SR 16137. Use of a dual-target STS inhibitor and SERM represents a new strategy in the treatment of hormone-dependent breast cancer. In this study, we tested the potential of SR 16157 and SR 16137 on STS activity, cell growth and ERalpha function in MCF-7 breast cancer cells. We confirmed that the dual-target compound SR 16157 exerts STS inhibition and antiestrogenic effects. SR 16157 was a highly effective growth inhibitor, being 10 times more potent than the antiestrogens SR 16137 and tamoxifen. Relative to tamoxifen, SR 16137 displays profoundly improved ERalpha binding affinity and antiestrogenic effects on expression of estrogen-regulated genes. Thus, the dual-target SR 16157 is possibly a promising new treatment alternative, superior to tamoxifen.

The reinforcement of invasion in epithelial ovarian cancer cells by 17β-Estradiol is associated with up-regulation of Snail

OBJECTIVE

The transcription factor Snail, which is implicated in the triggering of epithelial-mesenchymal transitions (EMT), plays an important role in adhesion, invasion and metastasis of tumor cells. In the present study, we assessed 17beta-Estradiol (E2)'s effect on Snail, E-cadherin and MMP-2 expression of epithelial ovarian cancer cell line ES-2 and SKOV3. Then we induced Snail gene silencing by RNA interference to explore the effect of E2 on E-cadherin and MMP-2 expression when Snail gene expression was blocked.

METHODS

Treated by 10(-8) M E2, Snail, E-cadherin and MMP-2 mRNA expression of the cells was measured by RT-PCR; Snail, MMP-2 protein expression was detected by IHC; and MMP-2 activity was determined by Zymography. E-cadherin protein level was measured by Western blot. We constructed the small interfering dsRNA expression vector (pRNAT-U6.1/Neo-Snail) targeting Snail gene, as well as a negative control vector (pRNAT-U6.1/Neo-Neg). Then the cells were transiently transfected with the vectors. Western blot and zymography were conducted to determine E-cadherin protein level and matrix metalloproteinase activity of the cells transfected with pRNAT-U6.1/Neo-Snail or pRNAT-U6.1/Neo-Neg after treated with E2 for 24 h.

RESULTS

The expression of ER alpha mRNA and protein was negative in ES-2 cells and positive in SKOV3 cells, and ER beta expression was positive in both cell lines. 10(-8) mol/l E2 elevated expression of Snail and MMP-2 mRNA and protein in both ES-2 and SKOV3 cells, and reduced expression of E-cadherin mRNA and protein in SKOV3 cells. While in the RNAi group transfected with the small interfering dsRNA expression vector (pRNAT-U6.1/Neo-Snail) targeting Snail gene, E2 treatment did not have a significant effect on MMP-2 activity or E-cadherin protein in ES-2 and SKOV3 cells.

CONCLUSIONS

17beta-Estradiol increased Snail expression in both ER alpha-negative ES-2 cells and ER alpha-positive SKOV3 cells independent of the existence of ER alpha. The increase of MMP-2 expression in ES-2 and SKOV3 cells and decrease of E-cadherin expression in SKOV3 cells induced by E2 were associated with up-regulation of Snail.

Endocrine signaling in ovarian surface epithelium and cancer

Ovarian cancer is the sixth most common cancer and the fifth leading cause of cancer-related death among women in developed countries. Greater than 85% of human ovarian cancer arises within the ovarian surface epithelium (OSE), with the remainder derived from granulosa cells or, rarely, stroma or germ cells. The pathophysiology of ovarian cancer is the least understood among all major human malignancies because of a poor understanding of the aetiological factors and mechanisms of ovarian cancer progression. There is increasing evidence suggesting that several key reproductive hormones, such as GnRH, gonadotrophins and sex steroids, regulate the growth of normal OSE and ovarian cancer cells. The objective of this review was to highlight the effects of these endocrine factors on ovarian cancer cell growth and to summarize the signalling mechanisms involved in normal human OSE and its neoplastic counterparts.

Breast cancer biomarkers

Substantial progress has been made over the past three decades in our understanding of the epidemiology, clinical course and basic biology of breast cancer. This chapter considers the existing ancillary tests and emerging molecular markers in breast cancer prognosis assessment and the prediction of response of breast cancer to treatment of the disease.

Lysosomes and autophagy in cell death control

Lysosomal hydrolases participate in the digestion of endocytosed and autophagocytosed material inside the lysosomal/autolysosomal compartment in acute cell death when released into the cytosol and in cancer progression following their release into the extracellular space. Lysosomal alterations are common in cancer cells. The increased expression and altered trafficking of lysosomal enzymes participates in tissue invasion, angiogenesis and sensitization to the lysosomal death pathway. But lysosomal heat-shock protein 70 locally prevents lysosomal-membrane permeabilization. Similarly, alterations in the autophagic compartment are linked to carcinogenesis and resistance to chemotherapy. Targeting these pathways might constitute a novel approach to cancer therapy.

Sex steroid regulation of angiogenesis in breast tissue

Angiogenesis is essential for normal function in the female reproductive tract and a prerequisite for growth and metastasis of solid tumors. Several factors, both inducers and inhibitors, play essential roles in the regulation of the angiogenic process. Exposure to sex steroids increases the risk of breast cancer but the mechanisms are poorly understood and the importance of angiogenesis in breast carcinogenesis is undefined. In the female reproductive tract ovarian hormones tightly regulate angiogenesis. The breast is also a target organ for sex steroids but very little is known about sex steroid effects on angiogenesis in normal breast tissue and breast cancer. In this review several regulators of angiogenesis, and their relation to sex steroids, in breast tissue are discussed. Increased knowledge in this area is of utmost importance for future therapeutic treatment options and for breast cancer prevention.

Sensitization to the Lysosomal Cell Death Pathway upon Immortalization and Transformation

Tumorigenesis is associated with several changes that alter the cellular susceptibility to programmed cell death. Here, we show that immortalization and transformation sensitize cells in particular to the cysteine cathepsin-mediated lysosomal death pathway. Spontaneous immortalization increased the susceptibility of wild-type murine embryonic fibroblasts (MEFs) to tumor necrosis factor (TNF)-mediated cytotoxicity >1000-fold, whereas immortalized MEFs deficient for lysosomal cysteine protease cathepsin B (CathB) retained the resistant phenotype of primary cells. This effect was specific for cysteine cathepsins, because also lack of cathepsin L (a lysosomal cysteine protease), but not that of cathepsin D (a lysosomal aspartyl protease) or caspase-3 (the major executioner protease in classic apoptosis) inhibited the immortalization-associated sensitization of MEFs to TNF. Oncogene-driven transformation of immortalized MEFs was associated with a dramatic increase in cathepsin expression and additional sensitization to the cysteine cathepsin-mediated death pathway. Importantly, exogenous expression of CathB partially reversed the resistant phenotype of immortalized CathB-deficient MEFs, and the inhibition of CathB activity by pharmacological inhibitors or RNA interference attenuated TNF-induced cytotoxicity in immortalized and transformed wild-type cells. Thus, tumorigenesis-associated changes in lysosomes may counteract cancer progression and enhance therapeutic responses by sensitizing cells to programmed cell death.

Estrogens and epithelial ovarian cancer

OBJECTIVE

Molecular mechanisms involved in ovarian carcinogenesis are still unclear, but there is growing evidence that estrogens promote tumor progression in an epithelial ovarian cancer (EOC) subgroup.

METHODS

We reviewed current knowledge on the effects of estrogens in ovarian carcinogenesis and new potential research focuses concerning hormonal therapy of EOC.

RESULTS

Experimentally, estrogen stimulates the growth of ovarian tumor cell lines expressing estrogen receptors (ER). We and other authors have demonstrated differential expression of ERalpha or beta during ovarian carcinogenesis, with overexpression of ERalpha as compared to ERbeta in cancer. This differential expression in ER suggests that estrogen-induced proteins may act as ovarian tumor-promoting agents. Among these proteins, c-myc, fibulin-1, cathepsin-D, or several kallikreins may play a role, since high expression levels have been found in EOC. Consistently, recent prospective epidemiological studies have indicated that estrogen replacement therapy in postmenopausal women may increase ovarian cancer incidence and mortality.

CONCLUSION

Questions on the estrogen-sensitivity and potential benefits of new hormone therapies in an EOC subgroup should be readdressed in the light of recent experimental and clinical data.

Expression profiling of breast cancer cells by differential peptide display

Expression profiling of RNAs or proteins has become a promising means to investigate the heterogeneity of histopathologically defined classes of cancer. Peptides, representing degradation as well as processing products of proteins offer an even closer insight into cell physiology. Peptides are related to the turnover of cellular proteins and are capable to reflect disease-related changes in homoeostasis of the human body. Furthermore, peptides derived from tumor cells are potentially useful markers in the early detection of cancer. In this study, we introduced a method called differential peptide display (DPD) for separating, detecting, and identifying native peptides derived from whole cell extracts. This method is a highly standardized procedure, combining the power of reversed-phase chromatography with mass spectrometry. This technology is suitable to analyze cell lines, various tissue types and human body fluids. Peptide-based profiling of normal human mammary epithelial cells (HMEC) and the breast cancer cell line MCF-7 revealed complex peptide patterns comprising of up to 2300 peptides. Most of these peptides were common to both cell lines whereas about 8% differed in their abundance. Several of the differentially expressed peptides were identified as fragments of known proteins such as intermediate filament proteins, thymosins or Cathepsin D. Comparing cell lines with native tumors, overlapping peptide patterns were found between HMEC and a phylloides tumor (CP) on the one hand and MCF-7 cells and tissue from a invasive ductal carcinoma (DC) on the other hand.