Progesterone downregulation of miR-141 contributes to expansion of stem-like breast cancer cells through maintenance of progesterone receptor and Stat5a. Oncogene. 2015;34:3676-3687. [PMID: 25241899 DOI: 10.1038/onc.2014.298]

Site specific O-GlcNAcylation of progesterone receptor (PR) supports PR attenuation of interferon stimulated genes (ISGs) and tumor growth in breast cancer

Hormone receptor (HR) positive breast cancer, defined by expression of estrogen (ER) and/or progesterone (PR) receptor expression, is the most commonly diagnosed type of breast cancer. PR alters the transcriptional landscape to support tumor growth in concert with or independent of ER. Thus, understanding the mechanisms regulating PR function are critical to developing new strategies to treat HR+ breast cancer. O-GlcNAc is a post-translational modification responsible for nutrient sensing that modulates protein function. Although PR is heavily post-translationally modified, through phosphorylation and O-GlcNAcylation, specific sites of O-GlcNAcylation on PR and how they regulate PR action, have not been investigated. Using established PR-expressing breast cancer cell lines, we mapped several sites of O-GlcNAcylation on PR. RNA-sequencing after PR O-GlcNAc site mutagenesis revealed site-specific O-GlcNAcylation of PR is critical for ligand-independent suppression of interferon signaling, a regulatory function of PR in breast cancer. Furthermore, O-GlcNAcylation of PR enhances PR-driven tumor growth in vivo. We have delineated one contributing mechanism to PR function in breast cancer that impacts tumor growth, and provided additional insight into the mechanism through which PR attenuates interferon signaling.

Progesterone Receptor Signaling Promotes Cancer Associated Fibroblast Mediated Tumorigenicity in ER+ Breast Cancer

Breast cancer progression involves intricate interactions between cancer cells and the tumor microenvironment (TME). This study elucidates the critical role of progesterone receptor (PR) signaling in mediating the protumorigenic effects of cancer-associated fibroblasts (CAFs) on estrogen receptor-positive (ER+) luminal breast cancer cells. We demonstrate that CAFs produce physiologically relevant levels of estrogen and progesterone, which significantly contribute to breast cancer tumorigenicity. Specifically, CAF conditioned media (CM) promoted PR-dependent anchorage-independent growth, tumorsphere formation/stem cell expansion, and CD44 upregulation. CAF cells formed co-clusters more frequently with PR+ breast cancer cells relative to PR-null models. While both PR isoforms mediated these actions, PR-A was a dominant driver of tumorsphere formation/stemness, while PR-B induced robust CD44 expression and CAF/tumor cell co-cluster formation. CD44 knockdown impaired CAF/tumor cell co-clustering. Fibroblast growth factor 2 (FGF2), also secreted by CAFs, phosphorylated PR (Ser294) in a MAPK-dependent manner and activated PR to enhance CD44 expression and breast cancer tumorigenicity. The FGF receptor (FGFR) inhibitor PD173074 diminished CAF- and FGF2-dependent PR activation, tumorsphere formation, and co-clustering. In summary, this study reveals a novel mechanism through which stromal CAFs orchestrate elevated PR signaling in ER+ luminal breast cancer via secretion of both progesterone and FGF2, a potent activator of ERK1/2. Understanding tumor cell/TME interactions provides insights into potential therapeutic strategies aimed at disrupting PR- and/or FGF2/FGFR-dependent signaling pathways to prevent early metastasis in patients with ER+ breast cancer.

Dynamic interplay of nuclear receptors in tumor cell plasticity and drug resistance: Shifting gears in malignant transformations and applications in cancer therapeutics

Recent advances have brought forth the complex interplay between tumor cell plasticity and its consequential impact on drug resistance and tumor recurrence, both of which are critical determinants of neoplastic progression and therapeutic efficacy. Various forms of tumor cell plasticity, instrumental in facilitating neoplastic cells to develop drug resistance, include epithelial-mesenchymal transition (EMT) alternatively termed epithelial-mesenchymal plasticity, the acquisition of cancer stem cell (CSC) attributes, and transdifferentiation into diverse cell lineages. Nuclear receptors (NRs) are a superfamily of transcription factors (TFs) that play an essential role in regulating a multitude of cellular processes, including cell proliferation, differentiation, and apoptosis. NRs have been implicated to play a critical role in modulating gene expression associated with tumor cell plasticity and drug resistance. This review aims to provide a comprehensive overview of the current understanding of how NRs regulate these key aspects of cancer biology. We discuss the diverse mechanisms through which NRs influence tumor cell plasticity, including EMT, stemness, and metastasis. Further, we explore the intricate relationship between NRs and drug resistance, highlighting the impact of NR signaling on chemotherapy, radiotherapy and targeted therapies. We also discuss the emerging therapeutic strategies targeting NRs to overcome tumor cell plasticity and drug resistance. This review also provides valuable insights into the current clinical trials that involve agonists or antagonists of NRs modulating various aspects of tumor cell plasticity, thereby delineating the potential of NRs as therapeutic targets for improved cancer treatment outcomes.

Screening and validation of novel serum panel of microRNA in stratification of prostate cancer

Background

Owing to the heterogeneous nature of prostate cancer (PCa) and errors in the characterization of the disease, researchers have been trying to unveil molecular biomarkers like microRNA (miRNA) as diagnostic markers. The purpose of our study is to demonstrate the precision of a panel of miRNAs as biomarkers with diagnostic potential for risk stratification.

Materials and methods

The present study demonstrates the comparative expression profiles of miRNA-141,-1290,-100, and -335 in both tissue and serum, including Benign Prostate Hyperplasia (BPH) and PCa, with healthy volunteers. Firstly, we demonstrate the expression of all miRNAs in the discovery cohort, including metastasis and benign tissue, and later validate their non-invasive diagnostic potential in BPH and PCa with healthy volunteers. MiRNA was isolated from tissue and serum to be quantified by RT-PCR and analyzed for biomarker potential by receiver operating characteristic (ROC) curve analysis, followed by targetome analysis of each miRNA.

Results

Among the non-invasive miRNA assessed, it was seen that miRNA 141 (P = 0.0003) and miRNA 1290 (P < 0.0001) are oncogenic with significantly higher expression, while miRNA 100 (P = 0.0002) and miRNA 335 are tumor suppressor, in PCa as compared to controls. While for BPH, miRNA 141 (P = 0.003) and miRNA 335 (P = 0.0002) were found to be significantly oncogenic and tumor suppressors, respectively. The analysis of the ROC curve of panel miRNAs (miRNA-141,-1290, and -100) portrayed a significant area under the curve with greater sensitivity and specificity. Moreover, in-silico prediction of their respective targetomes represents their extensive involvement in PCa progression and various other cascades that aid in PCa networks.

Conclusions

To the best of our knowledge, we are going to report for the first time this panel of miRNA that can be used to accurately and efficiently diagnose BPH and PCa patients from healthy males.

Identification of potential microRNA diagnostic panels and uncovering regulatory mechanisms in breast cancer pathogenesis

Early diagnosis of breast cancer (BC), as the most common cancer among women, increases the survival rate and effectiveness of treatment. MicroRNAs (miRNAs) control various cell behaviors, and their dysregulation is widely involved in pathophysiological processes such as BC development and progress. In this study, we aimed to identify potential miRNA biomarkers for early diagnosis of BC. We also proposed a consensus-based strategy to analyze the miRNA expression data to gain a deeper insight into the regulatory roles of miRNAs in BC initiation. Two microarray datasets (GSE106817 and GSE113486) were analyzed to explore the differentially expressed miRNAs (DEMs) in serum of BC patients and healthy controls. Utilizing multiple bioinformatics tools, six serum-based miRNA biomarkers (miR-92a-3p, miR-23b-3p, miR-191-5p, miR-141-3p, miR-590-5p and miR-190a-5p) were identified for BC diagnosis. We applied our consensus and integration approach to construct a comprehensive BC-specific miRNA-TF co-regulatory network. Using different combination of these miRNA biomarkers, two novel diagnostic models, consisting of miR-92a-3p, miR-23b-3p, miR-191-5p (model 1) and miR-92a-3p, miR-23b-3p, miR-141-3p, and miR-590-5p (model 2), were obtained from bioinformatics analysis. Validation analysis was carried out for the considered models on two microarray datasets (GSE73002 and GSE41922). The model based on similar network topology features, comprising miR-92a-3p, miR-23b-3p and miR-191-5p was the most promising model in the diagnosis of BC patients from healthy controls with 0.89 sensitivity, 0.96 specificity and area under the curve (AUC) of 0.98. These findings elucidate the regulatory mechanisms underlying BC and represent novel biomarkers for early BC diagnosis.

Giredestrant reverses progesterone hypersensitivity driven by estrogen receptor mutations in breast cancer

ESR1 (estrogen receptor 1) hotspot mutations are major contributors to therapeutic resistance in estrogen receptor-positive (ER⁺) breast cancer. Such mutations confer estrogen independence to ERα, providing a selective advantage in the presence of estrogen-depleting aromatase inhibitors. In addition, ESR1 mutations reduce the potency of tamoxifen and fulvestrant, therapies that bind ERα directly. These limitations, together with additional liabilities, inspired the development of the next generation of ERα-targeted therapeutics, of which giredestrant is a high-potential candidate. Here, we generated Esr1 mutant-expressing mammary gland models and leveraged patient-derived xenografts (PDXs) to investigate the biological properties of the ESR1 mutations and their sensitivity to giredestrant in vivo. In the mouse mammary gland, Esr1 mutations promote hypersensitivity to progesterone, triggering pregnancy-like tissue remodeling and profoundly elevated proliferation. These effects were driven by an altered progesterone transcriptional response and underpinned by gained sites of ERα-PR (progesterone receptor) cobinding at the promoter regions of pro-proliferation genes. PDX experiments showed that the mutant ERα-PR proliferative program is also relevant in human cancer cells. Giredestrant suppressed the mutant ERα-PR proliferation in the mammary gland more so than the standard-of-care agents, tamoxifen and fulvestrant. Giredestrant was also efficacious against the progesterone-stimulated growth of ESR1 mutant PDX models. In addition, giredestrant demonstrated activity against a molecularly characterized ESR1 mutant tumor from a patient enrolled in a phase 1 clinical trial. Together, these data suggest that mutant ERα can collaborate with PR to drive protumorigenic proliferation but remain sensitive to inhibition by giredestrant.

High Levels of Progesterone Receptor B in MCF-7 Cells Enable Radical Anti-Tumoral and Anti-Estrogenic Effect of Progestin

The widely reported conflicting effects of progestin on breast cancer suggest that the progesterone receptor (PR) has dual functions depending on the cellular context. Cell models that enable PR to fully express anti-tumoral properties are valuable for the understanding of molecular determinant(s) of the anti-tumoral property. This study evaluated whether the expression of high levels of PR in MCF-7 cells enabled a strong anti-tumoral response to progestin. MCF-7 cells were engineered to overexpress PRB by stable transfection. A single dose of Promegestone (R5020) induced an irreversible cell growth arrest and senescence-associated secretory phenotype in MCF-7 cells with PRB overexpression (MCF-7PRB cells) but had no effect on MCF-7 cells with PRA overexpression. The growth-arresting effect was associated with downregulations of cyclin A2 and B1, CDK2, and CDK4 despite an initial upregulation of cyclin A2 and B1. R5020 also induced an evident activation of Nuclear Factor κB (NF-κB) and upregulation of interleukins IL-1α, IL-1β, and IL-8. Although R5020 caused a significant increase of CD24+CD44+ cell population, R5020-treated MCF-7PRB cells were unable to form tumorspheres and underwent massive apoptosis, which is paradoxically associated with marked downregulations of the pro-apoptotic proteins BID, BAX, PARP, and Caspases 7 and 8, as well as diminution of anti-apoptotic protein BCL-2. Importantly, R5020-activated PRB abolished the effect of estrogen. This intense anti-estrogenic effect was mediated by marked downregulation of ERα and pioneer factor FOXA1, leading to diminished chromatin-associated ERα and FOXA1 and estrogen-induced target gene expression. In conclusion, high levels of agonist-activated PRB in breast cancer cells can be strongly anti-tumoral and anti-estrogenic despite the initial unproductive cell cycle acceleration. Repression of ERα and FOXA1 expression is a major mechanism for the strong anti-estrogenic effect.

Endocrine regulation of cancer stem cell compartments in breast tumors

Cancer cells within breast tumors exist within a hierarchy in which only a small and rare subset of cells is able to regenerate growths with the heterogeneity of the original tumor. These highly malignant cancer cells, which behave like stem cells for new cancers and are called "cancer stem cells" or CSCs, have also been shown to possess increased resistance to therapeutics, and represent the root cause underlying therapy failures, persistence of residual disease, and relapse. As >90% of cancer deaths are due to refractory tumors, identification of critical molecular drivers of the CSC-state would reveal vulnerabilities that can be leveraged in designing therapeutics that eradicate advanced disease and improve patient survival outcomes. An expanding and complex body of work has now described the exquisite susceptibility of CSC pools to the regulatory influences of local and systemic hormones. Indeed, breast CSCs express a plethora of hormonal receptors, which funnel hormonal influences over every aspect of breast neoplasia - be it tumor onset, growth, survival, invasion, metastasis, or therapy resistance - via directly impacting CSC behavior. This article is intended to shed light on this active area of investigation by attempting to provide a systematic and comprehensive overview of the available evidence directly linking hormones to breast CSC biology.

Progesterone Receptors Promote Quiescence and Ovarian Cancer Cell Phenotypes via DREAM in p53-Mutant Fallopian Tube Models

CONTEXT

The ability of ovarian steroids to modify ovarian cancer (OC) risk remains controversial. Progesterone is considered to be protective; recent studies indicate no effect or enhanced OC risk. Knowledge of progesterone receptor (PR) signaling during altered physiology that typifies OC development is limited.

OBJECTIVE

This study defines PR-driven oncogenic signaling mechanisms in p53-mutant human fallopian tube epithelia (hFTE), a precursor of the most aggressive OC subtype.

METHODS

PR expression in clinical samples of serous tubal intraepithelial carcinoma (STIC) lesions and high-grade serous OC (HGSC) tumors was analyzed. Novel PR-A and PR-B isoform-expressing hFTE models were characterized for gene expression and cell cycle progression, emboli formation, and invasion. PR regulation of the DREAM quiescence complex and DYRK1 kinases was established.

RESULTS

STICs and HGSC express abundant activated phospho-PR. Progestin promoted reversible hFTE cell cycle arrest, spheroid formation, and invasion. RNAseq/biochemical studies revealed potent ligand-independent/-dependent PR actions, progestin-induced regulation of the DREAM quiescence complex, and cell cycle target genes through enhanced complex formation and chromatin recruitment. Disruption of DREAM/DYRK1s by pharmacological inhibition, HPV E6/E7 expression, or DYRK1A/B depletion blocked progestin-induced cell arrest and attenuated PR-driven gene expression and associated OC phenotypes.

CONCLUSION

Activated PRs support quiescence and pro-survival/pro-dissemination cell behaviors that may contribute to early HGSC progression. Our data support an alternative perspective on the tenet that progesterone always confers protection against OC. STICs can reside undetected for decades prior to invasive disease; our studies reveal clinical opportunities to prevent the ultimate development of HGSC by targeting PRs, DREAM, and/or DYRKs.

Expression analysis of progesterone‑regulated miRNAs in cells derived from human glioblastoma

Glioblastomas (GBMs) are the most frequent and malignant type of brain tumor. It has been reported that progesterone (P4) regulates the progression of GBMs by modifying the expression of genes that promote cell proliferation, migration and invasion; however, it is not fully understood how these processes are regulated. It is possible that P4 mediates some of these effects through changes in the microRNA (miRNA) expression profile in GBM cells. The present study investigated the effects of P4 on miRNAs expression profile in U-251MG cells derived from a human GBM. U-251MG cells were treated for 6 h with P4, RU486 (an antagonist of the intracellular progesterone receptor), the combined treatment (P4+RU486) and cyclodextrin (vehicle) and then a miRNA microarray analysis conducted. The expression analysis revealed a set of 190 miRNAs with differential expression in the treatments of P4, RU486 and P4+RU486 in respect to the vehicle and P4 in respect to P4+RU486, of which only 16 were exclusively regulated by P4. The possible mRNA targets of the miRNAs regulated by P4 could participate in the regulation of proliferation, cell cycle progression and cell migration of GBMs. The present study provided insight for understanding epigenetic modifications regulated by sex hormones involved in GBM progression, and for identifying potential therapeutic strategies for these brain tumors.

Long non-coding RNA NEAT1 transported by extracellular vesicles contributes to breast cancer development by sponging microRNA-141-3p and regulating KLF12

Objective

Breast cancer (BC) remains a public-health issue on a global scale. Long non-coding RNAs (lncRNAs) play functional roles in BC. This study focuses on effects of NEAT1 on BC cell invasion, migration and chemotherapy resistance via microRNA (miR)-141-3p and KLF12.

Methods

After extraction and identification of serum extracellular vesicles (EVs), NEAT1 expression in EVs was detected and its association with clinical characteristics of BC patients was analyzed. Besides, the gain-of function was performed to investigate the roles of NEAT1 and miR-141-3p in BC, and levels of NEAT1, miR-141-3p, KLF12 and MDR1 after EV treatment were detected by RT-qPCR and Western blot analysis. Furthermore, the in vitro findings were confirmed via lung metastases in nude mice.

Results

NEAT1 expression in serum EVs was high and related to lymph node metastasis, progesterone receptor, estrogen receptor and Ki-67 in BC patients. After EV treatment, NEAT1 and KLF12 levels were increased, miR-141-3p expression was decreased, the abilities of proliferation, invasion, migration and in vivo metastasis were enhanced, and the sensitivity of cells to cisplatin, paclitaxel and 5-fluorouracil was decreased. After NEAT1 interference, NEAT1 and KLF12 levels in BC cells treated with EVs were decreased, miR-141-3p expression was increased, cell proliferation, invasion, migration and in vivo metastasis were decreased, and drug resistance sensitivity was increased. NEAT1 can bind to miR-141-3p and upregulates KLF12 expression.

Conclusions

EVs inhibit the regulation of KLF12 by miR-141-3p by transporting NEAT1 to BC cells, thus promoting BC cell invasion, migration, and chemotherapy resistance.

MicroRNA Regulation of Breast Cancer Stemness

Recent advances in our understanding of breast cancer have demonstrated that cancer stem-like cells (CSCs, also known as tumor-initiating cell (TICs)) are central for progression and recurrence. CSCs are a small subpopulation of cells present in breast tumors that contribute to growth, metastasis, therapy resistance, and recurrence, leading to poor clinical outcome. Data have shown that cancer cells can gain characteristics of CSCs, or stemness, through alterations in key signaling pathways. The dysregulation of miRNA expression and signaling have been well-documented in cancer, and recent studies have shown that miRNAs are associated with breast cancer initiation, progression, and recurrence through regulating CSC characteristics. More specifically, miRNAs directly target central signaling nodes within pathways that can drive the formation, maintenance, and even inhibition of the CSC population. This review aims to summarize these research findings specifically in the context of breast cancer. This review also discusses miRNAs as biomarkers and promising clinical therapeutics, and presents a comprehensive summary of currently validated targets involved in CSC-specific signaling pathways in breast cancer.

LncRNAs and microRNAs as Essential Regulators of Stemness in Breast Cancer Stem Cells

Breast cancer is an aggressive disease with a high incidence in women worldwide. Two decades ago, a controversial hypothesis was proposed that cancer arises from a subpopulation of “tumor initiating cells” or “cancer stem cells-like” (CSC). Today, CSC are defined as small subset of somatic cancer cells within a tumor with self-renewal properties driven by the aberrant expression of genes involved in the maintenance of a stemness-like phenotype. The understanding of the underlying cellular and molecular mechanisms involved in the maintenance of CSC subpopulation are fundamental in the development and persistence of breast cancer. Nowadays, the hypothesis suggests that genetic and epigenetic alterations give rise to breast cancer stem cells (bCSC), which are responsible for self-renewal, tumor growth, chemoresistance, poor prognosis and low survival in patients. However, the prominence of bCSC, as well as the molecular mechanisms that regulates and promotes the malignant phenotypes, are still poorly understood. The role of non-coding RNAs (ncRNAs), such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) acting as oncogenes or tumor suppressor genes has been recently highlighted by a plethora of studies in breast cancer. These ncRNAs positively or negatively impact on different signaling pathways that govern the cancer hallmarks associated with bCSC, making them attractive targets for therapy. In this review, we present a current summary of the studies on the pivotal roles of lncRNAs and microRNAs in the regulation of genes associated to stemness of bCSC.

Nanosized Drug Delivery Systems for Breast Cancer Stem Cell Targeting

Breast cancer stem cells (BCSCs), also known as breast cancer initiating cells, are reported to be responsible for the initiation, progression, therapeutic resistance, and relapse of breast cancer. Conventional therapeutic agents mainly kill the bulk of breast tumor cells and fail to eliminate BCSCs, even enhancing the fraction of BCSCs in breast tumors sometimes. Therefore, it is essential to develop specific and effective methods of eliminating BCSCs that will enhance the efficacy of killing breast tumor cells and thereby, increase the survival rates and quality of life of breast cancer patients. Despite the availability of an increasing number of anti-BCSC agents, their clinical translations are hindered by many issues, such as instability, low bioavailability, and off-target effects. Nanosized drug delivery systems (NDDSs) have the potential to overcome the drawbacks of anti-BCSC agents by providing site-specific delivery and enhancing of the stability and bioavailability of the delivered agents. In this review, we first briefly introduce the strategies and agents used against BCSCs and then highlight the mechanism of action and therapeutic efficacy of several state-of-the-art NDDSs that can be used to treat breast cancer by eliminating BCSCs.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

Comprehensive Analysis of ESRRA in Endometrial Cancer

BACKGROUND

Estrogen-related receptor alpha (ESRRA) was reported to play an important role in multiple biological processes of neoplastic diseases. The roles of ESRRA in endometrial cancer have not been fully investigated yet.

METHODS

Expression data and clinicopathological data of patients with uteri corpus endometrial carcinoma (UCEC) were obtained from The Cancer Genome Atlas (TCGA). Comprehensive bioinformatics analysis was performed, including receiver operating characteristics (ROC) curve analysis, Kaplan-Meier survival analysis, gene ontology (GO) enrichment analysis, and Gene Set Enrichment Analysis (GSEA). Immunohistochemistry was used to detect the protein expression level of ESRRA and CCK-8 assay was performed to evaluate the effect of ESRRA on the proliferation ability.

RESULTS

A total of 552 UCEC tissues and 35 normal tissues were obtained from the TCGA database. The mRNA and protein expression level of ESRRA was highly elevated in UCEC compared with normal tissues, and was closely associated with poor prognosis. ROC analysis indicated a very high diagnostic value of ESRRA for patients with UCEC. GO and GSEA functional analysis showed that ESRRA might be mainly involved in cellular metabolism processes, in turn, tumorigenesis and progression of UCEC. Knockdown of ESRRA inhibited the proliferation of UCEC cells in vitro. Further immune cell infiltration demonstrated that ESRRA enhanced the infiltration level of neutrophil cell and reduced that of T cell (CD4+ naïve), NK cell, and cancer associated fibroblast (CAF). The alteration of immune microenvironment will greatly help in developing immune checkpoint therapy for UCEC.

CONCLUSIONS

Our study comprehensively analyzed the expression level, clinical value, and possible mechanisms of action of ESRRA in UCEC. These findings showed that ESRRA might be a potential diagnostic and therapeutic target.

Potential Diagnostic and Prognostic Utility of miR-141, miR-181b1, and miR-23b in Breast Cancer

miRNAs, a group of short noncoding RNAs, are key regulators of fundamental cellular processes and signaling pathways. Dysregulation of miRNA expression with known oncogenic or tumor suppressor functions has been associated with neoplastic transformation. Numerous studies have reported dysregulation of miRNA-141, miR-181b1, and miR-23b in a wide range of malignancies, including breast cancer. To the best of our knowledge, no previous study had demonstrated the expression of miR-141-3p, miR-181b1-5p, and miR-23b-3p in different histological grades and molecular subtypes of breast cancer. Here, we identified differential expression of these three miRNAs in breast cancer tissues compared with benign breast fibroadenomas. In addition, high expression levels of miR-141-3p and miR-181b1-5p are strongly associated with aggressive breast carcinomas. We also confirmed the clinical potential of using the three miRNAs individually or combined as diagnostic and prognostic markers in breast cancer. Using bioinformatics analyses, we identified 23 hub genes of these three miRNAs which are involved in key signaling pathways in breast cancer. Furthermore, the KM plotter online database analysis demonstrates the association between elevated expression of miR-141 and miR-181b and shorter overall survival of breast cancer patients. Together, our data suggest an oncogenic role of the studied miRNAs and highlight their molecular roles and potential clinical applications in breast cancer.

Involvement of the Estrogen and Progesterone Axis in Cancer Stemness: Elucidating Molecular Mechanisms and Clinical Significance

Estrogen and progesterone regulate the growth and development of human tissues, including the reproductive system and breasts, through estrogen and progesterone receptors, respectively. These receptors are also important indicators for the clinical prognosis of breast cancer and various reproductive cancers. Many studies have reported that cancer stem cells (CSCs) play a key role in tumor initiation, progression, metastasis, and recurrence. Although the role of estrogen and progesterone in human organs and various cancers has been studied, the molecular mechanisms underlying the action of these hormones on CSCs remain unclear. Therefore, further elucidation of the effects of estrogen and progesterone on CSCs should provide a new direction for developing pertinent therapies. In this review, we summarize the current knowledge on the estrogen and progesterone axis involved in cancer stemness and discuss potential therapeutic strategies to inhibit CSCs by targeting relevant pathways.

microRNA Expression Profile in Single Hormone Receptor-Positive Breast Cancers is Mainly Dependent on HER2 Status-A Pilot Study

Estrogen (ER) and progesterone (PgR) receptors and HER2 are crucial in the assessment of breast cancer specimens due to their prognostic and predictive significance. Single hormone receptor-positive breast cancers are less common and their clinical course is less favorable than ER(+)/PgR(+) tumors. Their molecular features, especially microRNA (miRNA) profiles, have not been investigated to date. Tumor specimens from 36 chemonaive breast cancer patients with known ER and PgR status (18 ER(+)/PgR(−) and 18 ER(−)/PgR(+) cases) were enrolled to the study. The expression of 829 miRNAs was evaluated with nCounter Human v3 miRNA expression Assay (NanoString). miRNAs differentiating between ER/PgR/HER2 phenotypes were selected based on fold change (FC) calculated for the mean normalized counts of each probe in compared groups. The differences were estimated with Student’s t-test or Two-Way ANOVA (considering also the HER2 status). The results were validated using The Cancer Genome Atlas (TCGA) dataset. Following quality control of raw data, fourcases were excluded due to low sample quality, leaving 14 ER(+)/PgR(−) and 18 ER(−)/PgR(+) cases. After correction for multiple comparisons, we did not find miRNA signature differentiating between ER(−)/PgR(+) and ER(+)/PgR(−) breast cancers. However, a trend for differing expression (p-value ≤ 0.05; FDR > 0.2; ANOVA) in eight miRNAs was observed. The ER(+)/PgR(−) group demonstrated elevated levels of four miRNAs—miR-30a-5p, miR-29c-3p, miR-141-3p and miR-423-5p—while the ER(−)/PgR(+) tumors were enriched in another four miRNAs—miR-514b-5p, miR-424-5p, miR-495-3p, and miR-92a-3p. For one of the miRNAs—miR-29c-3p—the association with the ER(+)/PgR(−) phenotype was confirmed in the TCGA cohort (p-value = 0.024; t-test). HER2 amplification/overexpression in the NanoString cohort was related to significant differences observed in 33 miRNA expression levels (FDR ≤ 0.2; ANOVA). The association with HER2 status was confirmed in the TCGA cohort for four miRNAs (miR-1180-3p, miR-223-3p, miR-30d-5p, and miR-195-5p). The main differences in miRNA expression amongst single hormone receptor-positive tumors were identified according to their HER2 status. However, ER(+)/PgR(−) cases tended to express higher levels of miRNAs associated with ER-positivity (miR-30a-5p, miR-29c-3p, miR-141-3p), whereas ER(−)/PgR(+) cancers showed elevated levels of miRNAs characteristic for double- and triple-negative tumors (miR-92a-3p, miR-424-5p). Further studies are necessary to comprehensively analyze miRNA signatures characteristic of ER(−)/PgR(+) and ER(+)/PgR(−) tumors.

90 YEARS OF PROGESTERONE: Progesterone and progesterone receptors in breast cancer: past, present, future

Progesterone and progesterone receptors (PR) have a storied albeit controversial history in breast cancers. As endocrine therapies for breast cancer progressed through the twentieth century from oophorectomy to antiestrogens, it was recognized in the 1970s that the presence of estrogen receptors (ER) alone could not efficiently predict treatment responses. PR, an estrogen regulated protein, became the first prognostic and predictive marker of response to endocrine therapies. It remains today as the gold standard for predicting the existence of functional, targetable ER in breast malignancies. PRs were subsequently identified as highly structured transcription factors that regulate diverse physiological processes in breast cancer cells. In the early 2000s, the somewhat surprising finding that prolonged use of synthetic progestin-containing menopausal hormone therapies was associated with increased breast cancer incidence raised new questions about the role of PR in 'tumorigenesis'. Most recently, PR have been linked to expansion of cancer stem cells that are postulated to be the principal cells reactivated in occult or dormant disease. Other studies establish PR as dominant modulators of ER activity. Together, these findings mark PR as bona fide targets for progestin or antiprogestin therapies, yet their diverse actions have confounded that use. Here we summarize the early history of PR in breast cancer; debunk the theory that progesterone causes cancer; discuss recent discoveries that PR regulate cell heterogeneity; attempt to unify theories describing PR as either good or bad actors in tumors; and discuss emerging areas of research that may help explain this enigmatic hormone and receptor.

circGNB1 Facilitates Triple-Negative Breast Cancer Progression by Regulating miR-141-5p-IGF1R Axis

As an intriguing class of RNA, circular RNAs (circRNAs) are vital mediators of various diseases including cancers. However, the biological role and underlying mechanism of the majority of circRNAs are still ambiguous in the progression of triple-negative breast cancer (TNBC). In this study, we characterized and further investigated hsa_circ_0009362 (circGNB1) by reanalyzing the circRNA microarray profiling in our previous study. Validating by qRT-PCR, circGNB1 was overexpressed in TNBC cell lines and high expression of circGNB1 was associated with worse clinical features and survival outcomes. The expression of circGNB1 was positively correlated with tumor size and clinical stage, and high expression of circGNB1 was an independent risk factor for TNBC patients. Cell proliferation, colony formation, wound-healing and mouse xenograft assays were carried out to investigate the functions of circGNB1. Both in vitro and in vivo assays revealed that knockdown of circGNB1 significantly suppressed cell proliferation, migration and tumor growth. Subsequently, we performed luciferase reporter assays and RNA immunoprecipitation assays to elucidate the underlying molecular mechanism of circGNB1. The results showed that circGNB1 sponges miR-141-5p and facilitates TNBC progression by upregulating IGF1R. Altogether, our study demonstrated the pivotal role of circGNB1-miR-141-5p-IGF1R axis in TNBC growth and metastasis though the mechanism of competing endogenous RNAs. Therefore, circGNB1 may have the potential to be a therapeutic target and novel prognostic biomarker for TNBC.

Regulatory Mechanism of MicroRNA Expression in Cancer

Altered gene expression is the primary molecular mechanism responsible for the pathological processes of human diseases, including cancer. MicroRNAs (miRNAs) are virtually involved at the post-transcriptional level and bind to 3' UTR of their target messenger RNA (mRNA) to suppress expression. Dysfunction of miRNAs disturbs expression of oncogenic or tumor-suppressive target genes, which is implicated in cancer pathogenesis. As such, a large number of miRNAs have been found to be downregulated or upregulated in human cancers and to function as oncomiRs or oncosuppressor miRs. Notably, the molecular mechanism underlying the dysregulation of miRNA expression in cancer has been recently uncovered. The genetic deletion or amplification and epigenetic methylation of miRNA genomic loci and the transcription factor-mediated regulation of primary miRNA often alter the landscape of miRNA expression in cancer. Dysregulation of the multiple processing steps in mature miRNA biogenesis can also cause alterations in miRNA expression in cancer. Detailed knowledge of the regulatory mechanism of miRNAs in cancer is essential for understanding its physiological role and the implications of cancer-associated dysfunction and dysregulation. In this review, we elucidate how miRNA expression is deregulated in cancer, paying particular attention to the cancer-associated transcriptional and post-transcriptional factors that execute miRNA programs.

MicroRNA-141-5p Acts as a Tumor Suppressor via Targeting RAB32 in Chronic Myeloid Leukemia

MicroRNA-141-5p (miR-141-5p), an important member of the miR-200 family, has been reported to be involved in cellular proliferation, migration, invasion, and drug resistance in different kinds of human malignant tumors. However, the role and function of miR-141-5p in chronic myeloid leukemia (CML) are unclear. In this current study, we found that the level of miR-141-5p was significantly decreased in peripheral blood cells from CML patients compared with normal blood cells and human leukemic cell line (K562 cells) compared with normal CD34⁺ cells, but was remarkably elevated in patients after treatment with nilotinib or imatinib. Suppression of miR-141-5p promoted K562 cell proliferation and migration in vitro. As expected, overexpression of miR-141-5p weakened K562 cell proliferation, migration, and promoted cell apoptosis. A xenograft model in nude mice showed that overexpression of miR-141-5p markedly suppressed tumor growth in vivo. Mechanistic studies suggested that RAB32 was the potential target of miR-141-5p, and silencing of RAB32 suppressed the proliferation and migration of K562 cells and promoted cell apoptosis. Taken together, our study demonstrates that miR-141-5p plays an important role in the activation of K562 cells in vitro and may act as a tumor suppressor via targeting RAB32 in the development of CML.

Influence of MicroRNA-141 on Inhibition of the Proliferation of Bone Marrow Mesenchymal Stem Cells in Steroid-Induced Osteonecrosis via SOX11

Objective

To investigate whether miR‐141 and the sex determination region of Y chromosome box 11 (SOX11) play roles in steroid‐induced avascular necrosis of the femoral head (SANFH), and to explore whether miR‐141 could target SOX11 to influence the proliferation of bone marrow mesenchymal stem cells (BMSC).

Methods

Bone marrow mesenchymal stem cells (BMSC) were isolated and cultured from 4‐week‐old Sprague Dawley rats. A flow cytometry assay was performed to identify BMSC. BMSC were divided into two groups: a control group and a dexamethasone (DEX) group. BMSC were transfected by miR‐141 mimic, miR‐141 inhibitor, and SOX11. Real‐time polymerase chain reaction (PCR) assay was performed to investigate the mRNA expression of miR‐141 and SOX11. The results were used to determine the effect of transfection and to verify the expression in each group and the association between miR‐141 and SOX11. Luciferase reporter assay revealed the targeted binding site between miR‐141 and the 3′‐untranslated region of SOX11 mRNA. MTT assays were performed to investigate the proliferation of BMSC in the miR‐141 mimic, miR‐141 inhibitor, and SOX11 groups.

Result

The results of the flow cytometry assay suggested that cells were positive for CD29 and CD90 while negative for CD45. This meant that the isolated and cultured cells were not hematopoietic stem cells. In addition, cell transfection was successful based on the expression of miR‐141 and SOX11. According to the results of real‐time PCR assay, the mRNA expression of miR‐141 in SANFH was upregulated (4.117 ± 0.042 vs 1 ± 0.027, P < 0.001), while SOX11 was downregulated (0.611 ± 0.055 vs 1 ± 0.027, P < 0.001) compared with the control group. Based on the results of the luciferase experiment, MiR‐141 could directly target the expression of SOX11. Inhibition of miR‐141 could upregulate the expression of SOX11 (2.623 ± 0.220 vs 1 ± 0.095, P < 0.001) according to the results of a real‐time PCR assay. MiR‐141 inhibited the proliferation of BMSC (0.618 ± 0.092 vs 1.004 ± 0.082, P < 0.001), while suppression of miR‐141 increased the proliferation of BMSC (0.960 ± 0.095 vs 0.742 ± 0.091, P < 0.001). Furthermore, according to the results of the MTT assay, SOX11 promoted the proliferation of BMSC (1.064 ± 0.093 vs 0.747 ± 0.090, P < 0.001).

Conclusion

MiR‐141 inhibited the proliferation of BMSC in SANFH by targeting SOX11. Inhibition of miR‐141 upregulated the expression of SOX11 and promoted the proliferation of BMSC. MiR‐141 and SOX11 could be new targets for investigating the mechanism of SANFH.

Multifunctional Nanodelivery Platform for Maximizing Nucleic Acids Combination Therapy

The silencing of an oncogene with a small interfering RNA (siRNA) is a promising way for cancer therapy. Its efficacy can be further enhanced by integrating with other therapeutics; however, transporting siRNA and other active ingredients to the same location at the same time is challenging. Here, we report a novel multifunctional nanodelivery platform by sequentially layering several functional ingredients, such as siRNAs, microRNAs, peptides, and targeting ligands, onto a core through charge-charge interaction. The prepared nanovectors effectively and programmably delivered multiple active components to maximize therapeutic combination with minimal off-targeting effects.

miR-520b Promotes Breast Cancer Stemness Through Hippo/YAP Signaling Pathway

Introduction

The breast cancer stem cells contribute to the initiation, progression, recurrence, metastasis as well as resistance of breast cancer. However, the mechanisms underlying the maintenance of breast cancer stemness have not been fully understood.

Materials and methods

TCGA and GEO data were used for measuring miR-520b expression in breast cancer tissues. Kaplan-meier analysis was used for determining the relationship between miR-520b expression level and the prognosis of patients. Genetic manipulation was performed by lentivirus system and miR-520b inhibitor was used for knockdown of miR-520b. qRT-PCR and Western blot were employed to determine the mRNA and protein levels, respectively. The stemness and EMT (Epithelial to mesenchymal transition) were assessed by sphere-formation and transwell assay as well as the expression of the related markers. The target genes of miR-520b were identified using the online database starBase V3.0.

Results

miR-520b is upregulated in cancer tissues of breast cancer patients and predicts poor prognosis. Upregulation of miR-520b was found in breast cancer stem cells. Ectopic expression of miR-520b promotes the stemness of the breast cancer cells, conversely, depletion of miR-520b attenuates the stemness of these cells. miR-520b positively regulates Hippo/YAP signaling pathway and overexpression of LAST2 abolished the effect of miR-520b on the stemness of breast cancer cells.

Conclusion

miR-520b promotes the stemness of breast cancer patients by activating Hippo/YAP signaling via targeting LATS2.

Breast Cancer Stem Cells and Sex Steroid Hormones

Breast cancer stem cells (BCSCs) are a small population of tumor-initiating cells that express stem cell-associated markers. In recent years, their properties and mechanisms of regulation have become the focus of intense research due to their intrinsic resistance to conventional cancer therapies. This review describes breast cancer stem cell origin, signaling pathways involved in self-renewal, such as Wnt, Notch and Hedgehog, biomarkers linked to stemness, and the role of sex steroid hormones in BCSC regulation.

Molecular mechanisms underlying progesterone receptor action in breast cancer: Insights into cell proliferation and stem cell regulation

The ovarian steroid hormone progesterone and its nuclear receptor, the Progesterone Receptor (PR), play an essential role in the regulation of cell proliferation and differentiation in the mammary gland. In addition, experimental and clinical evidence demonstrate their critical role in controlling mammary gland tumorigenesis and breast cancer development. When bound to its ligand, the main action of PR is as a transcription factor, which regulates the expression of target genes networks. PR also activates signal transduction pathways through a rapid or non-genomic mechanism in breast cancer cells, an event that is fully integrated with its genomic effects. This review summarizes the molecular mechanisms of the ligand-activated PR actions that drive epithelial cell proliferation and the regulation of the stem cell population in the normal breast and in breast cancer.

Breast cancer stem cells: The role of sex steroid receptors

Breast cancer (BC) is the most common cancer among women, and current available therapies often have high success rates. Nevertheless, BC might acquire drug resistance and sometimes relapse. Current knowledge about the most aggressive forms of BC points to the role of specific cells with stem properties located within BC, the so-called “BC stem cells” (BCSCs). The role of BCSCs in cancer formation, growth, invasiveness, therapy resistance and tumor recurrence is becoming increasingly clear. The growth and metastatic properties of BCSCs are regulated by different pathways, which are only partially known. Sex steroid receptors (SSRs), which are involved in BC etiology and progression, promote BCSC proliferation, dedifferentiation and migration. However, in the literature, there is incomplete information about their roles. Particularly, there are contrasting conclusions about the expression and role of the classical BC hormonal biomarkers, such as estrogen receptor alpha (ERα), together with scant, albeit promising information concerning ER beta (ERβ) and androgen receptor (AR) properties that control different transduction pathways in BCSCs. In this review, we will discuss the role that SRs expressed in BCSCs play to BC progression and recurrence and how these findings have opened new therapeutic possibilities.

Detection of Putative Stem-cell Markers in Invasive Ductal Carcinoma of the Breast by Immunohistochemistry: Does It Improve Prognostic/Predictive Assessments?

Introduction:

Experimental evidences from the last 2 decades supports the existence of a special type of neoplastic cell with stem-like features [cancer stem cell (CSC)] and their role in the pathophysiology and therapeutic resistance of breast cancer. However, their clinical value in human breast cancer has not been fully determined.

Materials and Methods:

An immunohistochemistry panel of 10 putative CSC markers (CD34, C-KIT, CD10, SOX-2, OCT 3/4, p63, CD24, CD44, CD133, and ESA/EPCAM) was applied to 74 cases of breast cancer, followed in a Regional Cancer Center of Minas Gerais State, Brazil, from 2004 to 2006. Possible associations between CSC markers and classic variables of clinicopathologic relevance were investigated.

Results:

The most frequently positive CSC markers were CD44, CD24, CD133, and ESA (the others were present in <15% of the cases). Two CSC profiles were defined: CD24⁻/CD44⁺ (CSC-1) and CD133⁺/ESA⁺ (CSC-2). CSC-1 was significantly associated to patients older than 40 years, tumors of <2.0 cm in diameter, early clinical stages (P<0.05), and increased death risk of 4 times (P=0.03; 95% confidence interval, 1.09-14.41). CSC-2 was related to increased relapse risk of 3.75 times (P=0.04; 95% confidence interval, 1.02-13.69).

Conclusion:

The detection of the most frequently positive CSC markers by immunohistochemistry is of clinicopathologic and prognostic relevance.

Proteomics contribution to the elucidation of the steroid hormone receptors functions

Steroid hormones have far-ranging biological impacts and more are continuously being uncovered. Over the last decades, proteomics approaches have become key to better understand biological processes. Due to multiple technical breakthroughs allowing for the concurrent identification and/or quantification of thousands of analytes using mass spectrometers, researchers employing proteomics tools today can now obtain truly holistic views of multiple facets of the human proteome. Here, we review how the field of proteomics has contributed to discoveries about steroid hormones, their receptors and their impact on human pathologies. In particular, the involvement of steroid receptors in cancer initiation, development, metastasis and treatment will be highlighted. Techniques at the forefront of the proteomics field will also be discussed to present how they can contribute to a better understanding of steroid hormone receptors.

LncRNA XIST enhanced TGF-β2 expression by targeting miR-141-3p to promote pancreatic cancer cells invasion

The level of expression of long non-coding RNA (LncRNA) X-inactive specific transcript (XIST) is up-regulated in pancreatic cancer (PC). However, the role of XIST in PC and the underlying mechanism are still unknown. The present study aimed to elucidate how XIST participates in PC and its potential target, miR-141-3p. We detected the XIST expression in PC tissues and cells by qRT-PCR. Cell proliferation was measured using a CCK8 kit, and the migration and invasion of cells was measured by Transwell assay. Silencing XIST and miR-141-3p was performed with transfection by Lipofectamine kit. Binding assay was conducted by luciferase reporter assay. Protein expression was examined by Western blot. These results indicate that (i) XIST is highly expressed in tumor tissues while miR-141-3p is down-regulated. (ii) Silencing XIST inhibits the pancreatic cell proliferation, migration and invasion. (iii) MiR-141-3p inhibitor alleviates the inhibitory effect by siXIST in PC cell lines. (iv) MiR-141-3p directly interacts with XIST and also negatively regulates transforming growth factor-β 2 (TGF-β2) expression. (v) Overexpression of XIST attenuates the inhibition of TGF-β2 expression by miR-141-3p. The conclusion, is that XIST could promote proliferation, migration and invasion of PC cells via miR-141-5p/TGF-β2 axis.

Screening and identification of novel specific markers of breast cancer stem cells

Breast cancer is the leading cause of death among women worldwide. Until recent years, triple negative breast cancer could be divided into 6 types according to different biomarkers with the development of sequence and microarray technology. However, these results rarely have therapeutic impact and still lack validation with the string criteria of clinical studies. Therefore, the present study aimed to screen novel markers of breast cancer stem cells and to verify the specificity in vitro and in vivo. In the present study, screening for phages specifically binding to breast cancer stem cells was performed, positive phage DNAs were extracted, and polypeptides were synthesized and labeled with FITC. The specificity of the polypeptides was identified in vitro and in vivo. Breast cancer stem cells were cultured and identified by flow cytometry. A phage random-peptide library was amplified and screened by culturing with breast cancer cells and breast cancer stem cells. The positive phage was identified by ELISA, and positive phage DNA was extracted. The DNA pellet was isolated and sent for external sequencing with the primer −96 gIII. Based on the sequencing results, a polypeptide was synthesized and labeled with FITC. The specificity to breast cancer stem cells was identified in vivo and vitro. Following three rounds of screening, the phage was enriched ~200-fold. Immunofluorescence demonstrated that two randomly selected phage clones, B8 and A3, had specific affinity to breast cancer stem cells. The results of the present study indicated that phage polypeptides that specifically bind to breast cancer stem cells were successfully screened through stem cell enrichment and phage display technology, which may be beneficial for targeted therapy and further study of breast cancer stem cells.

Molecular Predictors for Advanced Papillary Thyroid Carcinoma Recurrence

Despite its indolent course, one-third of the papillary thyroid carcinoma (PTC) cases relapses, which directly impact on the quality of patients' lives. The molecular predictors of recurrence of PTC are poorly defined. We aimed at evaluating the long-term (10-20 years) prognostic value of aggressiveness markers in advanced PTC. To this end, immunohistochemistry for BRAF^V600E, Estrogen receptor α, Progesterone receptor, Ki-67, and E-cadherin were performed in 53 primary advanced PTC from an up to 20 years follow-up patients from a well-characterized Brazilian cohort. Categorical data were summarized using frequencies and groups were compared using Chi-squared and Fisher's exact tests. The expressions of the aggressiveness markers were associated with clinical-pathological data using the single-covariate logistic regression analysis. The Kaplan-Meier method with the Log-rank and Peto tests was used to estimate the probability of PTC-free survival. Persistence and recurrence (active disease) were associated with age (≥55 years), tumor size (>2 cm), extrathyroidal extension, local aggressiveness, macroscopic lymph node metastasis, and TNM stage at initial treatment. The BRAF^V600E mutation status was associated with extrathyroidal extension, local aggressiveness, and inversely associated with distant metastasis at initial treatment. All progesterone receptor-positive patients had active disease and displayed a shorter time of PTC-free survival than the negative ones using the Kaplan-Meir analysis (p = 0.001, Log Rank; p = 0.005, Peto). Loss of E-cadherin expression was associated with an increase in the probability of active disease (OR = 3.75). BRAF^V600E could be useful as a biomarker of local aggressiveness, while PR positive and E-cadherin loss of expression could predict the recurrence of advanced PTC.

MicroRNA Dysregulation and Steroid Hormone Receptor Expression in Uterine Tissues of Rats with Endometriosis during the Implantation Window

Background:

Estrogen receptor (ER) and progesterone receptor (PR) are involved in endometriosis, but the involvement of microRNAs (miRNAs) is unknown. The aim of the study was to explore the correlation between miRNA and ER/PR in uterine tissues of rats with endometriosis during the implantation window.

Methods:

Twenty female Sprague-Dawley rats were randomized in three groups: endometriosis (n = 7), fat tissue control (n = 6), and normal (n = 7) groups. The female rats were mated and sacrificed on day 5 (implantation). Uterine tissues were obtained for hematoxylin-eosin staining, immunohistochemistry, and miRNA expression. Reverse transcription polymerase chain reaction (RT-PCR) was used to validate the expression of rno-miR-29c-3p, rno-miR-34c-5p, rno-miR-141-5p, rno-miR-24-1-5p, and rno-miR-490-5p.

Results:

The 475 miRNAs were found to differentially express between the endometriosis and normal control groups, with 127 being upregulated and 348 being downregulated. Expression of five miRNAs (rno-miR-29c-3p, rno-miR-34c-5p, rno-miR-141-5p, rno-miR-24-1-5p, and rno-miR-490-5p) were validated by RT-PCR and found to be differentially expressed among the three groups. Expression of ER and PR proteins (immunohistochemistry) in the glandular epithelium and endometrial stroma was significantly different among the three groups (all P < 0.05). Five miRNAs were involved in pathways probably taking part in implantation and fertility.

Conclusions:

The results suggested that miRNAs, ER, and PR could play important roles in the embryo implantation period of rats with endometriosis. These miRNAs might play a role in endometrial receptivity in endometriosis.

Carcinoma-associated fibroblasts promote the stemness and chemoresistance of colorectal cancer by transferring exosomal lncRNA H19

Long non-coding RNAs (lncRNAs) are involved in the pathology of various tumors, including colorectal cancer (CRC). The crosstalk between carcinoma- associated fibroblasts (CAFs) and cancer cells in the tumor microenvironment promotes tumor development and confers chemoresistance. In this study, we further investigated the underlying tumor-promoting roles of CAFs and the molecular mediators involved in these processes.

Methods: The AOM/DSS-induced colitis-associated cancer (CAC) mouse model was established, and RNA sequencing was performed. Small interfering RNA (siRNA) sequences were used to knock down H19. Cell apoptosis was measured by flow cytometry. SW480 cells with H19 stably knocked down were used to establish a xenograft model. The indicated protein levels in xenograft tumor tissues were confirmed by immunohistochemistry assay, and cell apoptosis was analyzed by TUNEL apoptosis assay. RNA-FISH and immunofluorescence assays were performed to assess the expression of H19 in tumor stroma and cancer nests. The AldeRed ALDH detection assay was performed to detect intracellular aldehyde dehydrogenase (ALDH) enzyme activity. Isolated exosomes were identified by transmission electron microscopy, nanoparticle tracking and Western blotting.

Results: H19 was highly expressed in the tumor tissues of CAC mice compared with the expression in normal colon tissues. The up-regulation of H19 was also confirmed in CRC patient samples at different tumor node metastasis (TNM) stages. Moreover, H19 was associated with the stemness of colorectal cancer stem cells (CSCs) in CRC specimens. H19 promoted the stemness of CSCs and increased the frequency of tumor-initiating cells. RNA-FISH showed higher expression of H19 in tumor stroma than in cancer nests. Of note, H19 was enriched in CAF-derived conditioned medium and exosomes, which in turn promoted the stemness of CSCs and the chemoresistance of CRC cells in vitro and in vivo. Furthermore, H19 activated the β-catenin pathway via acting as a competing endogenous RNA sponge for miR-141 in CRC, while miR-141 significantly inhibited the stemness of CRC cells.

Conclusion: CAFs promote the stemness and chemoresistance of CRC by transferring exosomal H19. H19 activated the β-catenin pathway via acting as a competing endogenous RNA sponge for miR-141, while miR-141 inhibited the stemness of CRC cells. Our findings indicate that H19 expressed by CAFs of the colorectal tumor stroma contributes to tumor development and chemoresistance.

Cancer epigenetics: Moving forward

Defects in chromatin modifiers and remodelers have been described both for hematological and solid malignancies, corroborating and strengthening the role of epigenetic aberrations in the etiology of cancer. Furthermore, epigenetic marks-DNA methylation, histone modifications, chromatin remodeling, and microRNA-can be considered potential markers of cancer development and progression. Here, we review whether altered epigenetic landscapes are merely a consequence of chromatin modifier/remodeler aberrations or a hallmark of cancer etiology. We critically evaluate current knowledge on causal epigenetic aberrations and examine to what extent the prioritization of (epi)genetic deregulations can be assessed in cancer as some type of genetic lesion characterizing solid cancer progression. We also discuss the multiple challenges in developing compounds targeting epigenetic enzymes (named epidrugs) for epigenetic-based therapies. The implementation of acquired knowledge of epigenetic biomarkers for patient stratification, together with the development of next-generation epidrugs and predictive models, will take our understanding and use of cancer epigenetics in diagnosis, prognosis, and treatment of cancer patients to a new level.

Nonredundant, Highly Connected MicroRNAs Control Functionality in Breast Cancer Networks

Alterations to transcriptional regulation are an important factor in breast cancer. Noncoding RNA, such as microRNA (miR), have very influential roles in the transcriptional regulation of genes. Transcriptional regulation can be successfully modeled and analyzed using complex network theory. Particularly, interactions between two distinct classes of biological elements, such as miR and genes, can be approached through the bipartite network formalism. Based on bipartite network properties, it is possible to identify highly influential miRs in the network, such as those that have a large number of connections indicating regulation of a large set of genes. Some miRs in a network are nonredundant, which indicates that they are solely responsible of the regulation of a particular set of genes, which in turn may be associated to a particular biological process. We hypothesize that highly influential, nonredundant miRs, which we call Commodore miRs (Cdre-miRs), have an important role on the control of biological functions through transcriptional networks. In this work, we analyze the regulation of gene expression by miRs in healthy and cancerous breast tissue using bipartite miR-gene networks inferred from the Cancer Genome Atlas (TCGA) expression data. We observe differences in the degree, clustering coefficient and redundancy distributions for miRs and genes in the network, indicating differences in the way that these elements interact with each other. Furthermore, we identify a small set of five Cdre-miRs in the breast cancer network: miR-190b, miR-let7i, miR-292-b, miR-511, and miR-141. The neighborhood of genes controlled by each of these miRs is involved in particular biological functions such as dynein structure-associated processes, immune response, angiogenesis, cytokine activity, and cell motility. We propose that these Cdre-miRs are important control elements of biological functions deregulated in breast cancer.

The Role of Steroid Hormones in Breast and Effects on Cancer Stem Cells

Purpose of Review

This review will discuss how the steroid hormones, estrogen and progesterone, as well as treatments that target steroid receptors, can regulate cancer stem cell (CSC) activity. The CSC theory proposes a hierarchical organization in tumors where at its apex lies a subpopulation of cancer cells endowed with self-renewal and differentiation capacity.

Recent Findings

In breast cancer (BC), CSCs have been suggested to play a key role in tumor maintenance, disease progression, and the formation of metastases. In preclinical models of BC, only a few CSCs are required sustain tumor re-growth, especially after conventional anti-endocrine treatments. CSCs include therapy-resistant clones that survive standard of care treatments like chemotherapy, irradiation, and hormonal therapy.

Summary

The relevance of hormones for both normal mammary gland and BC development is well described, but it was only recently that the activities of hormones on CSCs have been investigated, opening new directions for future BC treatments and CSCs.

Breast cancer stem cells-from origins to targeted therapy

Breast cancer is marked as one of the leading causes of malignancy-related morbidities worldwide. In spite of aggressive interventions, the inevitability of relapse and metastasis severely impede survival rates. Mounting evidence highlight the insidious role of cancer stem cells (CSCs), a small but significant subpopulation of undifferentiated cells that drive tumour progression, spread and resistance to conventional therapy. The nature and significance of breast CSCs remains poorly understood, and even disputed by many researchers. This review discusses the origins, biomarkers, signalling pathways, regulatory mechanisms, and targeted therapy of breast CSCs.

Cross talk between progesterone receptors and retinoic acid receptors in regulation of cytokeratin 5-positive breast cancer cells

Half of estrogen receptor-positive breast cancers contain a subpopulation of cytokeratin 5 (CK5)-expressing cells that are therapy resistant and exhibit increased cancer stem cell (CSC) properties. We and others have demonstrated that progesterone (P4) increases CK5+ breast cancer cells. We previously discovered that retinoids block P4 induction of CK5+ cells. Here we investigated the mechanisms by which progesterone receptors (PR) and retinoic acid receptors (RAR) regulate CK5 expression and breast CSC activity. After P4 treatment, sorted CK5+ compared to CK5- cells were more tumorigenic in vivo. In vitro, P4-treated breast cancer cells formed larger mammospheres and silencing of CK5 using small hairpin RNA abolished this P4-dependent increase in mammosphere size. Retinoic acid (RA) treatment blocked the P4 increase in CK5+ cells and prevented the P4 increase in mammosphere size. Dual small interfering RNA (siRNA) silencing of RARα and RARγ reversed RA blockade of P4-induced CK5. Using promoter deletion analysis, we identified a region 1.1 kb upstream of the CK5 transcriptional start site that is necessary for P4 activation and contains a putative progesterone response element (PRE). We confirmed by chromatin immunoprecipitation that P4 recruits PR to the CK5 promoter near the -1.1 kb essential PRE, and also to a proximal region near -130 bp that contains PRE half-sites and a RA response element (RARE). RA induced loss of PR binding only at the proximal site. Interestingly, RARα was recruited to the -1.1 kb PRE and the -130 bp PRE/RARE regions with P4, but not RA alone or RA plus P4. Treatment of breast cancer xenografts in vivo with the retinoid fenretinide reduced the accumulation of CK5+ cells during estrogen depletion. This reduction, together with the inhibition of CK5+ cell expansion through RAR/PR cross talk, may explain the efficacy of retinoids in prevention of some breast cancer recurrences.

Genome-wide miRNA response to anacardic acid in breast cancer cells

MicroRNAs are biomarkers and potential therapeutic targets for breast cancer. Anacardic acid (AnAc) is a dietary phenolic lipid that inhibits both MCF-7 estrogen receptor α (ERα) positive and MDA-MB-231 triple negative breast cancer (TNBC) cell proliferation with IC50s of 13.5 and 35 μM, respectively. To identify potential mediators of AnAc action in breast cancer, we profiled the genome-wide microRNA transcriptome (microRNAome) in these two cell lines altered by the AnAc 24:1n5 congener. Whole genome expression profiling (RNA-seq) and subsequent network analysis in MetaCore Gene Ontology (GO) algorithm was used to characterize the biological pathways altered by AnAc. In MCF-7 cells, 69 AnAc-responsive miRNAs were identified, e.g., increased let-7a and reduced miR-584. Fewer, i.e., 37 AnAc-responsive miRNAs were identified in MDA-MB-231 cells, e.g., decreased miR-23b and increased miR-1257. Only two miRNAs were increased by AnAc in both cell lines: miR-612 and miR-20b; however, opposite miRNA arm preference was noted: miR-20b-3p and miR-20b-5p were upregulated in MCF-7 and MDA-MB-231, respectively. miR-20b-5p target EFNB2 transcript levels were reduced by AnAc in MDA-MB-231 cells. AnAc reduced miR-378g that targets VIM (vimentin) and VIM mRNA transcript expression was increased in AnAc-treated MCF-7 cells, suggesting a reciprocal relationship. The top three enriched GO terms for AnAc-treated MCF-7 cells were B cell receptor signaling pathway and ribosomal large subunit biogenesis and S-adenosylmethionine metabolic process for AnAc-treated MDA-MB-231 cells. The pathways modulated by these AnAc-regulated miRNAs suggest that key nodal molecules, e.g., Cyclin D1, MYC, c-FOS, PPARγ, and SIN3, are targets of AnAc activity.

MicroRNAs, a subpopulation of regulators, are involved in breast cancer progression through regulating breast cancer stem cells

Cancer stem cells (CSCs; also known as tumor-initiating cells) are essential effectors of tumor progression due to their self-renewal capacity, differentiation potential, tumorigenic ability and resistance to chemotherapy, all of which contribute to cancer relapse, metastasis and a poor prognosis. Breast cancer stem cells (BCSCs) have been identified to be involved in the processes of BC initiation, growth and recurrence. MicroRNAs (miRNAs) are a class of non-coding small RNAs of 19-23 nucleotides in length that regulate gene expression at the post-transcriptional level through various mechanisms, and serve critical roles in cancer progression. miRNAs have been demonstrated to elicit effects on BCSCs characteristics via the targeting of oncogenes or tumor suppressor genes. The present study focused on the effect of miRNAs on BCSC, including BCSC formation, self-renewal and differentiation, by which miRNAs may inhibit BCSC invasion and metastasis, modulate clonogenicity and tumorigenicity of BCSCs as well as regulate chemotherapy resistance to BC. Through an improved understanding of the association between BCSCs and miRNAs, a novel and safer therapeutic target for BC may be identified.

Identification of aminosulfonylarylisoxazole as microRNA-31 regulators

The discovery of small-molecule regulators of microRNAs remains challenging, but a few have been reported. Herein, we describe small-molecule inhibitors of miR-31, a tumor-associated microRNA (miRNA), identified by high-throughput screening using a cell-based reporter assay. Aminosulfonylarylisoxazole compounds exhibited higher specificity for miR-31 than for six other miRNAs, i.e., miR-15a, miR-16, miR-21, miR-92a-1, miR-146a, and miR-155, and increased the expression of miR-31 target genes. The down-regulation of mature miR-31 was observed, while its precursor form increased following treatment with the compounds. Thus, the compounds may target the processing of pre-miR-31 into mature miR-31 and thereby inhibit the production of mature miR-31.

Breast Cancer Suppression by Progesterone Receptors Is Mediated by Their Modulation of Estrogen Receptors and RNA Polymerase III

Greater than 50% of estrogen receptor (ER)-positive breast cancers coexpress the progesterone receptor (PR), which can directly and globally modify ER action to attenuate tumor growth. However, whether this attenuation is mediated only through PR-ER interaction remains unknown. To address this question, we assessed tumor growth in ER/PR-positive patient-derived xenograft models of breast cancer, where both natural and synthetic progestins were found to antagonize the mitogenic effects of estrogens. Probing the genome-wide mechanisms by which this occurs, we documented that chronic progestin treatment blunted ER-mediated gene expression up to 2-fold at the level of mRNA transcripts. Unexpectedly, <25% of all ER DNA binding events were affected by the same treatment. The PR cistrome displayed a bimodal distribution. In one group, >50% of PR binding sites were co-occupied by ER, with a propensity for both receptors to coordinately gain or lose binding in the presence of progesterone. In the second group, PR but not ER was associated with a large fraction of RNA polymerase III-transcribed tRNA genes, independent of hormone treatment. Notably, we discovered that PR physically associated with the Pol III holoenzyme. Select pre-tRNAs and mature tRNAs with PR and POLR3A colocalized at their promoters were relatively decreased in estrogen + progestin-treated tumors. Our results illuminate how PR may indirectly impede ER action by reducing the bioavailability of translational molecules needed for tumor growth. Cancer Res; 77(18); 4934-46. ©2017 AACR.

A novel double-negative feedback loop between miR-489 and the HER2-SHP2-MAPK signaling axis regulates breast cancer cell proliferation and tumor growth

Human epidermal growth factor receptor 2 (HER2 or ErBb2) is a receptor tyrosine kinase overexpressed in 20-30% of breast cancers and associated with poor prognosis and outcome. Dysregulation of several microRNAs (miRNAs) plays a key role in breast cancer progression and metastasis. In this study, we screened and identified miRNAs dysregualted in HER2-positive breast cancer cells. Our molecular study demonstrated that miR-489 was specifically downregulated by the HER2-downstream signaling, especially through the MAPK pathway. Restoration or overexpression of miR-489 in HER2-positive breast cancer cells significantly inhibited cell growth in vitro and decreased the tumorigenecity and tumor growth in xenograft mice. Mechanistically, we found that overexpression of miR-489 led to the decreased levels of HER2 and SHP2 and thus attenuated HER2-downstream signaling. Furthermore, we for the first time demonstrated that HER2 is a direct target of miR-489 and therefore HER2-SHP2-MAPK and miR-489 signaling pathways form a mutually inhibitory loop. Using quantitative real-time PCR analysis and Fluorescent in situ hybridization technique (FISH), we found that miR-489 was expressed at significantly lower level in tumor tissues compared to the adjacent normal tissues. Downregulation of miR-489 in breast cancers was associated with aggressive tumor phenotypes. Overall, our results define a double-negative feedback loop involving miR-489 and the HER2-SHP2-MAPK signaling axis that can regulate breast cancer cell proliferation and tumor progression and might have therapeutic relevance for HER2-positive breast cancer.