ESF1 and MIPEP proteins promote estrogen receptor-positive breast cancer proliferation and are associated with patient prognosis.

BACKGROUND: Estrogen receptor-positive (ER+) breast cancer accounts for two-thirds of all breast cancers, and its early and late recurrences still threaten patients' long-term survival and quality of life. Finding candidate tumor antigens and potential therapeutic targets is critical to addressing these unmet needs. METHOD: The isobaric tags for relative and absolute quantitation (iTRAQ) proteomic analysis was employed to identify the differentially expressed proteins (DEPs) between ER + breast cancer and corresponding adjacent normal tissue. Candidate DEPs were screened by bioinformatic analyses, and their expression was confirmed by immunohistochemical (IHC) staining and western blot. A series of in vitro experiments, including wound healing assay, colony formation, and cell cycle assay, were performed to reveal the functions of selected DEPs. Additionally, their clinical significances were further analyzed. RESULT: A total of 369 DEPs (fold change ≥ 2.0 or ≤ 0.66, P < 0.05) were discovered. Compared with normal tissue, 358 proteins were up-regulated and 11 proteins were down-regulated in ER + breast cancer. GO and KEGG enrichment analysis showed that DEPs were closely associated with RNA regulation and metabolic pathways. STRING analysis found ESF1 and MIPEP were the hub genes in breast cancer, whose increased expressions were verified by the IHC staining and western blot. Knocking down ESF1 and MIPEP inhibited colony formation and increased cell apoptosis. Besides, knocking down ESF1 inhibited wound healing but not MIPEP. In addition, ESF1 and MIPEP expression were negatively associated with patient prognosis. CONCLUSION: The upregulation of ESF1 and MIPEP promoted ER + breast cancer proliferation, which might provide novel targets for the development of new therapies.

Epidemiology of early vs. Late recurrence among women with Early-Stage estrogen Receptor-Positive breast cancer in the pathways study.

BACKGROUND: Relatively little is known about the differences in prognostic factors for early vs late recurrence among women with early-stage estrogen receptor-positive (ER+) breast cancer. METHODS: We analyzed factors related to early (<5 years) vs late (≥5 years) recurrence in 2,992 women with stage I-IIB ER+ breast cancer in the Pathways Study, a prospective cohort of women with breast cancer enrolled between 2006 and 2013, with ascertainment of recurrence and death through December 2021. RESULTS: After a median follow-up of 13.3 years, 341 (13.8%) women had recurrences, including 181 (53.7%) with late recurrence. Higher stage and grade were associated with recurrence regardless of timing, whereas progesterone receptor (PR) negativity was associated with early but not late recurrence. Receipt of endocrine therapy was associated with reduced risk of overall recurrence, but the length of endocrine therapy was not significant in multivariable models. Minoritized racial and ethnic groups, including Asian, Black, and Hispanic women, had higher risk of early but not late recurrence, compared with non-Hispanic White women. The trend of higher risk of early recurrence among these groups remained after adjustment for clinical, demographic, and socioeconomic factors, but was statistically significant only in Asian women. CONCLUSIONS: Our study revealed potentially important distinctions for early vs late recurrence, including the associations with PR-negativity and self-identified race and ethnicity. Possible higher risk of early recurrence among Asian, Black, and Hispanic women provides novel evidence for the existence of disparities in cancer outcomes, even within the breast cancer subtype indicative of generally good prognosis.

Exploring a Novel Approach to Spare Classic Chemotherapy in HER2-Low, ER-Positive Breast Cancer Based on Trastuzumab Deruxtecan Combined with Endocrine Therapy.

BACKGROUND: Breast cancer presents diverse molecular subtypes affecting treatment strategies. Human epidermal growth factor receptor 2 (HER2)-low, hormone receptor-positive (HR+) breast cancer poses a challenge due to limited targeted therapies. Current neoadjuvant treatment primarily utilizes chemotherapy, with conflicting results regarding efficacy in patients with HER2-low breast cancer. Trastuzumab deruxtecan (T-DXd) shows promise in HER2-low metastatic disease, and preliminary evidence suggests synergy with endocrine therapy. OBJECTIVE: This editorial explores the hypothesis that neoadjuvant T-DXd with or without endocrine therapy offers efficacy in the clinical management of HR+/HER2-low breast cancer. METHODS: We propose a phase II study with two treatment arms: T-DXd + letrozole and T-DXd alone. The primary endpoint is the radiological complete response rate. Secondary endpoints include pathological complete response rate, safety, event-free survival, and overall survival. Exploratory analyses will compare the arms to identify potential for optimizing treatment efficacy and minimizing side effects. CONCLUSIONS: This study design allows for initial assessment of T-DXd with or without endocrine therapy in the treatment of HER2-low breast cancer. The findings may pave the way for personalized treatment strategies and inform future research, potentially leading to a chemotherapy-sparing approach.

Beyond the median: Estimating survival times for patients starting endocrine therapy for estrogen receptor-positive, metastatic breast cancer from recent randomized trials.

AIM: To estimate scenarios for survival for patients with estrogen receptor (ER) positive, metastatic breast cancer (MBC) and to help communicate prognosis to patients starting endocrine therapy (ET) METHODS: We searched for randomized trials of ET for ER-positive MBC and extracted the following percentiles (representative survival scenarios) from each overall survival (OS) curve: 90th (worst-case), 75th (lower-typical), 50th (median), 25th (upper-typical), and 10th (best-case). We then assessed the accuracy of estimating these percentiles for each OS curve by multiplying the median OS by four simple multiples: 0.25 (to estimate the 90th percentile), 0.5 (75th), 2 (25th), and 3 (10th). Estimates were deemed accurate if it fell within 0.75-1.33 times the actual value. RESULTS: We identified 25 trials with 10,566 patients. The median OS (interquartile range) was: 61.3 months (53.4-64.8) for first-line ET with cyclin-dependant kinase 4/6 inhibitors (four treatment groups); 42.6 months (40.9-50.4) for first-line ET alone (21 treatment groups) and 29.2 months (24.8-33.4) for subsequent line ET (19 treatment groups). Simple multiples of the median OS accurately estimated the 90th percentile in 80%; 75th percentile in 93%; and 25th percentile in 76% of curves. The 10th percentile was only available for four OS curves and could not be evaluated. CONCLUSION: Simple multiples of the median OS are a helpful and accurate method to assist in estimating and discussing scenarios for survival for MBC patients starting ET. Longer follow-up of trials is required to help clinicians estimate the best-case scenario.

Genomic analysis uncovers that cold-inducible RNA binding protein is associated with estrogen receptor in breast cancer.

BACKGROUND: RNA-binding proteins (RBPs) perform various biological functions in humans and are associated with several diseases, including cancer. Therefore, RBPs have emerged as novel therapeutic targets. Although recent investigations have shown that RBPs have crucial functions in breast cancer (BC), detailed research is underway to determine the RBPs that are closely related to cancers. OBJECTIVE: To provide an insight into estrogen receptor (ER) regulation by cold-inducible RNA binding protein (CIRBP) as a novel therapeutic target. RESULTS: By analyzing the genomic data, we identified a potential RBP in BC. We found that CIRBP is highly correlated with ER function and influences clinical outcomes, such as patient survival and endocrine therapy responsiveness. In addition, CIRBP influences the proliferation of BC cells by directly binding to ER-RNA. CONCLUSION: Our results suggest that CIRBP is a novel upstream regulator of ER and that the interplay between CIRBP and ER may be associated with the clinical relevance of BC.

heredERA Breast Cancer: a phase III, randomized, open-label study evaluating the efficacy and safety of giredestrant plus the fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection in patients with previously untreated HER2-positive, estrogen receptor-positive locally advanced or metastatic breast cancer.

BACKGROUND: HER2-positive, estrogen receptor-positive breast cancer (HER2+, ER+ BC) is a distinct disease subtype associated with inferior response to chemotherapy plus HER2-targeted therapy compared with HER2+, ER-negative BC. Bi-directional crosstalk leads to cooperation of the HER2 and ER pathways that may drive treatment resistance; thus, simultaneous co-targeting may optimize treatment impact and survival outcomes in patients with HER2+, ER+ BC. First-line (1L) treatment for patients with HER2+ metastatic BC (mBC) is pertuzumab, trastuzumab, and taxane chemotherapy. In clinical practice, dual HER2 blockade plus a fixed number of chemotherapy cycles are given as induction therapy to maximize tumor response, with subsequent HER2-targeted maintenance treatment given as a more tolerable regimen for long-term disease control. For patients whose tumors co-express ER, maintenance endocrine therapy (ET) can be added, but uptake varies due to lack of data from randomized clinical trials investigating the superiority of maintenance ET plus dual HER2 blockade versus dual HER2 blockade alone. Giredestrant, a novel oral selective ER antagonist and degrader, shows promising clinical activity and manageable safety across phase I-II trials of patients with ER+, HER2-negative BC, with therapeutic potential in those with HER2 co-expression. METHODS: This phase III, randomized, open-label, two-arm study aims to recruit 812 patients with HER2+, ER+ locally advanced (LA)/mBC into the induction phase (fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection [PH FDC SC] plus a taxane) to enable 730 patients to be randomized 1:1 to the maintenance phase (giredestrant plus PH FDC SC or PH FDC SC [plus optional ET]), stratified by disease site (visceral versus non-visceral), type of LA/metastatic presentation (de novo versus recurrent), best overall response to induction therapy (partial/complete response versus stable disease), and intent to give ET (yes versus no). The primary endpoint is investigator-assessed progression-free survival. Secondary endpoints include overall survival, objective response rate, clinical benefit rate, duration of response, safety, and patient-reported outcomes. DISCUSSION: heredERA BC will address whether giredestrant plus dual HER2 blockade is superior to dual HER2 blockade alone, to inform the use of this combination in clinical practice for maintenance 1L treatment of patients with HER2+, ER+ LA/mBC. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05296798; registered on March 25, 2022. Protocol version 3.0 (November 18, 2022). SPONSOR: F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124 4070, Basel, Switzerland.

Modeling of Mouse Experiments Suggests that Optimal Anti-Hormonal Treatment for Breast Cancer is Diet-Dependent.

Estrogen receptor positive breast cancer is frequently treated with anti-hormonal treatment such as aromatase inhibitors (AI). Interestingly, a high body mass index has been shown to have a negative impact on AI efficacy, most likely due to disturbances in steroid metabolism and adipokine production. Here, we propose a mathematical model based on a system of ordinary differential equations to investigate the effect of high-fat diet on tumor growth. We inform the model with data from mouse experiments, where the animals are fed with high-fat or control (normal) diet. By incorporating AI treatment with drug resistance into the model and by solving optimal control problems we found differential responses for control and high-fat diet. To the best of our knowledge, this is the first attempt to model optimal anti-hormonal treatment for breast cancer in the presence of drug resistance. Our results underline the importance of considering high-fat diet and obesity as factors influencing clinical outcomes during anti-hormonal therapies in breast cancer patients.

Impact of Alcohol Consumption on Breast Cancer Incidence and Mortality: The Women's Health Study.

Background: Alcohol intake is associated with breast cancer (BC) risk, but estimates of greatest public health relevance have not been quantified in large studies with long duration. Materials and Methods: In this prospective cohort study of 39,811 women (median 25 years follow-up), we examined the association between alcohol consumption and BC incidence and mortality with adjusted hazard ratios (HRs), cubic splines, absolute risks, number needed to harm (NNH), and population-attributable fractions. Results: We documented 2,830 cases of BC, including 237 BC deaths. Each additional alcoholic drink/day was associated with a 10% higher rate (HR = 1.10, 95% confidence intervals [CIs]: 1.04-1.16) of total BC in a linear manner (p = 0.0004). The higher rate was apparent for estrogen receptor (ER)+ (HR = 1.12, 95% CI: 1.06-1.18) but not ER- tumors (HR = 0.95, 95% CI: 0.82-1.10), with a statistically significant difference between these associations (p = 0.03). We constructed models comparing BC incidence among 100,000 women followed for 10 years. Compared to a scenario where all women rarely or never consumed alcohol, we expect 63.79 (95% CI: 58.35-69.24) more cases (NNH = 1,567) had all women consumed alcohol at least monthly and 278.66 (95% CI: 268.70-288.62) more cases (NNH = 358) had all women consumed >1 drink/day. Approximately 4.1% of BC cases were attributable to consumption exceeding one drink/month. Conclusion: Alcohol consumption is associated with a linear dose-response increase in BC incidence even within recommended limits of up to one alcoholic drink/day, at least for ER+ tumors. Our estimates of risk differences, attributable fraction, and NNH quantify the burden that alcohol consumption imposes on women in the general population. ClinicalTrials.gov Identifier: NCT00000479.

A Prospective Study of Sentinel Node Biopsy Omission in Women Age ≥ 65 Years with ER+ Breast Cancer.

BACKGROUND: National guidelines recommend omitting SNB in older patients with favorable invasive breast cancer. However, there is a lack of prospective data specifically addressing this issue. This study evaluates recurrence and survival in estrogen receptor-positive/Her2- (ER+) breast cancer patients, aged ≥ 65 years who have breast-conserving surgery (BCS) without SNB. METHODS: This is a prospective, observational study at a single institution where 125 patients aged ≥ 65 years with clinical T1-2N0 ER+ invasive breast cancer undergoing BCS were enrolled. Patients were treated with BCS without SNB. Primary outcome measure was axillary recurrence. Secondary outcome measures include recurrence-free survival (RFS), disease-free survival (DFS), breast cancer-specific survival (BCSS), and overall survival (OS). RESULTS: From January 2016 to July 2022, 125 patients were enrolled with median follow-up of 36.7 months [95% confidence interval (CI) 35.0-38.0]. Median age was 77.0 years (range 65-93). Median tumor size was 1 cm (range 0.1-5.0). Most tumors were ductal (95/124, 77.0%), intermediate grade (60/116, 51.7%), and PR-positive (117/123, 91.7%). Radiation therapy was performed in 37 of 125 (29.6%). Only 60 of 125 (48.0%) who were recommended hormonal therapy were compliant at 2 years. Chemotherapy was administered to six of 125 (4.8%) patients. There were two of 125 (1.6%) axillary recurrences. Estimated 3-years rates of regional RFS, DFS, and OS were 98.2%, 91.2%, and 94.8%, respectively. Univariate Cox regression identified hormonal therapy noncompliance to be significantly associated with recurrence (p = 0.02). CONCLUSIONS: Axillary recurrence rates were extremely low in this cohort. These results provide prospective data to support omission of SNB in this patient population TRIAL REGISTRATION: ClinicalTrials.gov ID NCT02564848.

Oral SERD, a Novel Endocrine Therapy for Estrogen Receptor-Positive Breast Cancer.

Breast cancer is the most common cancer among women worldwide, and estrogen receptor-positive (ER+) breast cancer accounts for a significant proportion of cases. While various treatments are available, endocrine therapies are often the first-line treatment for this type of breast cancer. However, the development of drug resistance poses a significant challenge in managing this disease. ESR1 mutations have been identified as a common mechanism of endocrine therapy resistance in ER+ breast cancer. The first-generation selective estrogen receptor degrader (SERD) fulvestrant has shown some activity against ESR1 mutant tumors. However, due to its poor bioavailability and need for intramuscular injection, it may not be the optimal therapy for patients. Second-generation SERDs were developed to overcome these limitations. These newer drugs have improved oral bioavailability and pharmacokinetics, making them more convenient and effective for patients. Several oral SERDs are now in phase III trials for early and advanced ER+ breast cancer. This review summarizes the background of oral SERD development, the current status, and future perspectives.

Combination of Palbociclib and Endocrine Therapy in Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative Metastatic Breast Cancer With or Without Brain Metastases.

OBJECTIVE: This real-world study aimed to investigate the efficacy and safety of palbociclib plus endocrine therapy in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer in the real world in a Chinese population. METHODS: The clinical data of consecutively enrolled patients from the Cancer Hospital Chinese Academy of Medical Sciences, Shenzhen Center, and the University of Hong Kong - Shenzhen Hospital were collected. Progression-free survival curves were generated using log-rank tests with the Kaplan-Meier method. Univariate and multivariate logistic regression analyses were performed to identify the factors affecting progression-free survival. RESULTS: In total, 118 patients were enrolled, including 6 patients with brain metastases. At the last follow-up date, the median progression-free survival was 16.8 months (95% confidence interval, 11.1-22.5), with the 6-month and 12-month progression-free survival rates of 77.1% and 57.6%, respectively. The disease control rate and the intracranial disease control rate were 82.2% and 50%, respectively. A longer progression-free survival was observed for patients with the following characteristics: treatment-naive; without hepatic metastasis; sensitive to previous endocrine therapy and harboring fewer metastatic sites. The multivariate logistic regression analysis demonstrated that treatment lines and exposure to palliative chemotherapy were independent influencing factors of progression-free survival. CONCLUSIONS: Palbociclib plus endocrine therapy in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer was effective and well-tolerated, even in patients with brain metastases. More benefits were observed in frontline therapy, chemotherapy-naive, and endocrine therapy-sensitive patients with fewer metastatic sites.

FOXK1 promotes hormonally responsive breast carcinogenesis by suppressing apoptosis.

BACKGROUND: Globally, breast cancer constitutes the predominant malignancy in women. Abnormal regulation of epigenetic factors plays a key role in the development of tumors. Anti-apoptosis is a characteristic of tumor cells. Therefore, exploring and identifying relevant epigenetic factors that regulate the apoptosis of tumor cells is the foundation for clarifying the pathogenesis of tumors and achieving precision antitumor therapy. METHOD: This study focused on exploring the epigenetic mechanism of FOXK1 in the development of estrogen receptor-positive (ER+ ) breast cancer. We used overexpressing FLAG-FOXK1 MCF-7 cells to perform silver staining mass spectrometry analysis and conducted Co-IP experiments to verify the interactions. ChIP-seq was conducted on MCF-7 cells to examine FOXK1's binding across the genome and its transcriptional target sites. To validate the ChIP-seq results, qChIP, western blotting, and quantitative polymerase chain reaction (qPCR) were performed. Through TUNEL assay, cell counting assay, colony formation assay, and the mouse xenograft models, the effect of FOXK1 on breast cancer progression was detected. Finally, by analyzing online databases, the correlation between FOXK1 and the survival of breast cancer patients was examined. RESULTS: FOXK1 interacts with the REST/CoREST transcriptional corepression complex to transcriptionally inhibit target genes representing the apoptotic pathway. Abnormally high expression of FOXK1 prevents the apoptosis of ER+ breast cancer cells in vitro and promotes ER+ breast tumor progression in vivo. Furthermore, the expression of FOXK1 is negatively correlated with the survival of ER+ breast cancer patients. CONCLUSION: FOXK1 promotes ER+ breast carcinogenesis through anti-apoptosis and acts as a potential target for ER+ breast cancer treatment.

Estrogen receptor positive breast cancer: contemporary nuances to sequencing therapy.

The treatment landscape of hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer has evolved dramatically in recent years. While the combination of endocrine therapy and a cyclin-dependent kinase 4/6 inhibitor is accepted as standard first-line treatment in most settings without visceral crisis, newer therapies have challenged traditional treatment models where cytotoxic chemotherapy was previously felt to be the only second-line option at time of progression. The incorporation of next-generation sequencing has led to the identification of molecular targets for therapeutic agents, including phosphatidylinositol 3-kinase and ESR1, though similar pathways can be targeted even in the absence of a mutation, such as with use of inhibitors of mammalian target of rapamycin. Current data also supports the use of cyclin-dependent kinase inhibitors beyond progression, even prior to the patient's first introduction to chemotherapy. The abundance of therapeutic options not only delay time to cytotoxic chemotherapy and antibody-drug conjugate initiation, but has resulted in improvement in breast cancer survivorship. Many unanswered questions remain, however, as to the most efficacious way to sequence these novel agents. To assist in this decision-making, we will review the existing data on systemic therapy and propose a treatment paradigm.

Causal pathways linking polycystic ovary syndrome to distinct breast cancer subtypes through mediator factors: a multivariable mendelian randomization analysis.

Polycystic ovary syndrome (PCOS) is an endocrine disorder characterized by ovarian cysts, high androgen levels, and irregular menstruation. The causality between PCOS and breast cancer (BC) has been widely discussed as they share a significant intersection in clinical manifestations. Previous epidemiological studies have not provided consistent conclusions in association between PCOS and BC, while mendelian randomization (MR) analyses have confirmed the causality between PCOS and estrogen receptor-positive breast cancer (ER + BC), but among a series of clinical manifestations resulting from PCOS, which related traits mediate the causal effect remains unknown. In this study, we conducted multivariable mendelian randomization (MVMR) analysis to explore the potential mediator variables in the mechanism linking PCOS to distinct subtypes of BC, and calculated the mediating effects proportion. We analyzed 13 PCOS-related traits and found that age at menopause may mediate PCOS-induced ER + BC (with -4.82% proportion) with a weak protective effect through the repair of DNA double-strand breaks by homologous recombination. This study helps to better comprehend the shared mechanisms contributing to the development of both PCOS and BC, and to screen high-risk populations for BC and take appropriate preventive measures.

Trop-2 Is Highly Expressed in Early Luminal-Like Breast Cancer.

Trop-2, a transmembrane glycoprotein, has been identified in human epithelial cells as a contributor to tumor growth and unfavorable prognosis in breast cancer (BC). Our study aimed to assess the expression of Trop-2 protein via immunohistochemistry (IHC) and correlate it with clinicopathological features in early luminal-like BC. We conducted a cross-sectional study evaluating Trop-2 protein expression in tissue microarrays using IHC. The expression was evaluated by the H-score and the following categorization was used: H-Score 0 to <100 as low, H-Score 100 to 200 as intermediate, and H-Score >200 to 300 as high. The study included 84 patients with a median age of 57, of whom 70% had invasive ductal carcinomas, 75% were classified as T2, and 47.6% had no affected lymph nodes. Trop-2 expression was high in 56% of patients and intermediate in 38%. None of the patients had an H-Score of zero. No correlation was observed between Trop-2 expression and clinicopathological features, including age, histological subtype, grade, Ki67, tumor size, nodal status, lymphovascular invasion, tumor subtype, and pathological staging. We demonstrated that Trop-2 is highly expressed in early luminal-like BC and is not influenced by clinicopathological features.

Meta-analysis of integrated ChIP-seq and transcriptome data revealed genomic regions affected by estrogen receptor alpha in breast cancer.

BACKGROUND: The largest group of patients with breast cancer are estrogen receptor-positive (ER+) type. The estrogen receptor acts as a transcription factor and triggers cell proliferation and differentiation. Hence, investigating ER-DNA interaction genomic regions can help identify genes directly regulated by ER and understand the mechanism of ER action in cancer progression. METHODS: In the present study, we employed a workflow to do a meta-analysis of ChIP-seq data of ER+ cell lines stimulated with 10 nM and 100 nM of E2. All publicly available data sets were re-analyzed with the same platform. Then, the known and unknown batch effects were removed. Finally, the meta-analysis was performed to obtain meta-differentially bound sites in estrogen-treated MCF7 cell lines compared to vehicles (as control). Also, the meta-analysis results were compared with the results of T47D cell lines for more precision. Enrichment analyses were also employed to find the functional importance of common meta-differentially bound sites and associated genes among both cell lines. RESULTS: Remarkably, POU5F1B, ZNF662, ZNF442, KIN, ZNF410, and SGSM2 transcription factors were recognized in the meta-analysis but not in individual studies. Enrichment of the meta-differentially bound sites resulted in the candidacy of pathways not previously reported in breast cancer. PCGF2, HNF1B, and ZBED6 transcription factors were also predicted through the enrichment analysis of associated genes. In addition, comparing the meta-analysis results of both ChIP-seq and RNA-seq data showed that many transcription factors affected by ER were up-regulated. CONCLUSION: The meta-analysis of ChIP-seq data of estrogen-treated MCF7 cell line leads to the identification of new binding sites of ER that have not been previously reported. Also, enrichment of the meta-differentially bound sites and their associated genes revealed new terms and pathways involved in the development of breast cancer which should be examined in future in vitro and in vivo studies.

Regulation of the stem­like properties of estrogen receptor­positive breast cancer cells through NR2E3/NR2C2 signaling.

Cancer stem cells (CSCs) are major drivers of metastasis, drug resistance and recurrence in numerous cancers. However, critical factors that can modulate CSC stemness have not been clearly identified. Nuclear receptor subfamily 2 group E member 3 (nr2e3) expression has been previously reported to be positively associated with drug sensitivity and favorable clinical outcomes in patients with estrogen receptor (ER)+ breast cancer. This suggests that nr2e3 expression may be inversely associated with CSC stemness in this type of tumor cells. The present study aimed to investigate the regulatory roles of NR2E3 in the stem-like properties of ER+ breast cancer cells and to identify the underlying mechanisms. Bioinformatics analysis was performed using the data derived from the Cancer Genome Atlas database. Nr2e3-specific shRNA and nuclear receptor subfamily 2 group C member 2 (nr2c2) overexpressed plasmids were constructed to silence and enhance the expression of nr2e3 and nr2c2, respectively. Transwell and wound healing experiments were conducted to evaluate the migration and invasion ability of MCF7 cells, while colony formation tests were used to evaluate the clonality. Flow cytometry was used to detect the percentage of CD44+CD24-/low cells. Reverse transcription-quantitative PCR and western blotting were performed to detect expression at the mRNA and protein levels. The results showed that compared with normal breast tissues and MCF10A cells, the expression of nr2e3 was increased in ER+ breast tumor tissues and cell lines. Nr2e3 silencing promoted the migration, invasion and colony-forming ability of the ER+ MCF7 cells. It also increased the expression of epithelial-mesenchymal transition markers and stem cell-related transcription factors, in addition to the percentage of CD44+CD24-/low cells. The expression of nr2e3 and nr2c2 was found to be positively correlated. Nr2e3 knockdown decreased the mRNA and protein expression levels of nr2c2, whereas nr2c2 overexpression reversed the elevated CD44+CD24-/low cell ratio and the increased migratory activity caused by nr2e3 silencing. The results of the present study suggest that NR2E3 may serve an important role in modulating the stem-like properties of ER+ breast cancer cells, where NR2E3/NR2C2 signaling may be a therapeutic target in ER+ breast cancer.

The PML1-WDR5 axis regulates H3K4me3 marks and promotes stemness of estrogen receptor-positive breast cancer.

The alternative splicing of PML precursor mRNA gives rise to various PML isoforms, yet their expression profile in breast cancer cells remains uncharted. We discovered that PML1 is the most abundant isoform in all breast cancer subtypes, and its expression is associated with unfavorable prognosis in estrogen receptor-positive (ER+) breast cancers. PML depletion reduces cell proliferation, invasion, and stemness, while heterologous PML1 expression augments these processes and fuels tumor growth and resistance to fulvestrant, an FDA-approved drug for ER + breast cancer, in a mouse model. Moreover, PML1, rather than the well-known tumor suppressor isoform PML4, rescues the proliferation of PML knockdown cells. ChIP-seq analysis reveals significant overlap between PML-, ER-, and Myc-bound promoters, suggesting their coordinated regulation of target gene expression, including genes involved in breast cancer stem cells (BCSCs), such as JAG1, KLF4, YAP1, SNAI1, and MYC. Loss of PML reduces BCSC-related gene expression, and exogenous PML1 expression elevates their expression. Consistently, PML1 restores the association of PML with these promoters in PML-depleted cells. We identified a novel association between PML1 and WDR5, a key component of H3K4 methyltransferase (HMTs) complexes that catalyze H3K4me1 and H3K4me3. ChIP-seq analyses showed that the loss of PML1 reduces H3K4me3 in numerous loci, including BCSC-associated gene promoters. Additionally, PML1, not PML4, re-establishes the H3K4me3 mark on these promoters in PML-depleted cells. Significantly, PML1 is essential for recruiting WDR5, MLL1, and MLL2 to these gene promoters. Inactivating WDR5 by knockdown or inhibitors phenocopies the effects of PML1 loss, reducing BCSC-related gene expression and tumorsphere formation and enhancing fulvestrant's anticancer activity. Our findings challenge the conventional understanding of PML as a tumor suppressor, redefine its role as a promoter of tumor growth in breast cancer and offer new insights into the unique roles of PML isoforms in breast cancer.

Hormone Receptor-Positive / HER2-Negative Early Breast Cancer High-Risk Population: An Algorithm for Optimization Systemic Adjuvant Treatment Based on 2022 Updates.

Prognostic and predictive factors for early and late distant distance recurrence risk in estrogen-receptor positive and HER2-receptor negative early breast cancer are well known, but not all these variables work equally for the prediction. The following are the most widely accepted variables for categorizing risk levels: clinic-pathologic features (tumor size, lymph node involvement, histological grade, age, menopausal status, Ki-67 expression, estrogen, and progesterone expression), primary systemic treatment response (pathologic response and/or Ki-67 downstaging), and gene expression signatures stratification. Treatment guidelines from cancer societies and collaborative groups, online predict-tools, real-world data and experts' opinion recommends different adjuvant strategies (chemotherapy, endocrine therapy, ovarian suppression, olaparib, or abemaciclib) depending on the low (< 10%), intermediate (10%-20%) or high-risk of distance recurrence at least in the first 5 years. Multiple randomized prospective trials were updated in 2022, that evidence allow us to perform a stratification of risk in pre- and postmenopausal women with estrogen-receptor positive and HER2-receptor negative early breast cancer based on a combination of clinic-pathologic features and genomic assays and guide the adjuvant systemic treatment recommendation for those with high risk.

F-box and leucine-rich repeat protein 16 controls tamoxifen sensitivity via regulation of mitochondrial respiration in estrogen receptor-positive breast cancer cells.

Tamoxifen is one of the most effective therapeutic tools for estrogen receptor-positive (ER +) breast cancer. However, the intrinsic insensitivity and resistance to tamoxifen remains a significant hurdle for achieving optimal responses and curative therapy. In this study, we report that F-box and leucine-rich repeat protein 16 (FBXL16) is located in the mitochondria of ER + breast cancer cells. The mitochondrial FBXL16 plays an essential role in sustaining mitochondrial respiration and thereby regulates the sensitivity of ER + breast cancer cells to tamoxifen treatment. Importantly, high FBXL16 expression is significantly correlated with poor overall survival of ER + breast cancer patients. Moreover, mitochondrial inhibition phenocopies FBXL16 depletion in terms of sensitizing the ER + breast cancer cells to tamoxifen treatment. Together, our study demonstrates that FBXL16 acts as a novel regulator of tamoxifen sensitivity. Thus, targeting FBXL16 may serve as a promising approach for improving the therapeutic efficacy of tamoxifen in ER + breast cancer cells.