UBE2M, a NEDD8-conjugating enzyme, is dysregulated in various human cancers and promotes tumor cell proliferation. However, its role in estrogen receptor-positive (ER+) breast cancer remains unknown. We found that UBE2M expression was significantly higher in ER+ breast cancer tissues than in ER-negative (ER-) breast cancer tissues. Higher expression of UBE2M indicated a poorer prognosis in patients with ER+ breast cancer but not in those with ER- breast cancer. Of interest, a positive feedback loop was observed between UBE2M and ERα. Specifically, ERα enhanced the HIF-1α-mediated transcription of UBE2M. In turn, UBE2M maintained ERα expression by inhibiting its ubiquitination and degradation through UBE2M-CUL3/4A-E6AP-ERα axis. Functionally, silencing of UBE2M suppressed the growth of breast cancer cells by inducing cell cycle arrest and apoptosis and improved their sensitivity to fulvestrant both in vitro and in vivo. Altogether, our findings reveal that the UBE2M-ERα feedback loop drives breast cancer progression and fulvestrant resistance, suggesting UBE2M as a viable target for endocrine therapy of ER+ breast cancer.

Identifying master epigenetic factors controlling proliferation and survival of cancer cells allows to discover new molecular targets exploitable to overcome resistance to current pharmacological regimens. In breast cancer (BC), resistance to endocrine therapy (ET) arises from aberrant Estrogen Receptor alpha (ERα) signaling caused by genetic and epigenetic events still mainly unknown. Targeting key upstream components of the ERα pathway provides a way to interfere with estrogen signaling in cancer cells independently from any other downstream event. By combining computational analysis of genome-wide \'drop-out\' screenings with siRNA-mediated gene knock-down (kd), we identified a set of essential genes in luminal-like, ERα + BC that includes BRPF1, encoding a bromodomain-containing protein belonging to a family of epigenetic readers that act as chromatin remodelers to control gene transcription. To gather mechanistic insights into the role of BRPF1 in BC and ERα signaling, we applied chromatin and transcriptome profiling, gene ablation and targeted pharmacological inhibition coupled to cellular and functional assays. Results indicate that BRPF1 associates with ERα onto BC cell chromatin and its blockade inhibits cell cycle progression, reduces cell proliferation and mediates transcriptome changes through the modulation of chromatin accessibility. This effect is elicited by a widespread inhibition of estrogen signaling, consequent to ERα gene silencing, in antiestrogen (AE) -sensitive and -resistant BC cells and pre-clinical patient-derived models (PDOs). Characterization of the functional interplay of BRPF1 with ERα reveals a new regulator of estrogen-responsive BC cell survival and suggests that this epigenetic factor is a potential new target for treatment of these tumors.

Sex steroids modulate the distribution of mammalian white adipose tissues. Moreover, WAT remodeling requires adipocyte progenitor cells. Nevertheless, the sex-dependent mechanisms regulating adipocyte progenitors remain undetermined. Here, we uncover Cxcr4 acting in a sexually dimorphic manner to affect a pool of proliferating cells leading to restriction of female fat mass. We find that deletion of Cxcr4 in Pparγ-expressing cells results in female, not male, lipodystrophy, which cannot be restored by high-fat diet consumption. Additionally, Cxcr4 deletion is associated with a loss of a pool of proliferating adipocyte progenitors. Cxcr4 loss is accompanied by the upregulation of estrogen receptor alpha in adipose-derived PPARγ-labelled cells related to estradiol hypersensitivity and stalled adipogenesis. Estrogen removal or administration of antiestrogens restores WAT accumulation and dynamics of adipose-derived cells in Cxcr4-deficient mice. These findings implicate Cxcr4 as a female adipogenic rheostat, which may inform strategies to target female adiposity.

BACKGROUND: Estrogen receptors express in nearly 70% of breast cancers (ER-positive). Estrogen receptor alpha plays a fundamental role as a significant factor in breast cancer progression for the early selection of therapeutic approaches. Accordingly, there has been a surge of attention to non-invasive techniques, including circulating Cell-free DNA (ccfDNA) or Cell-Free DNA (cfDNA), to detect and track ESR1 genotype. Therefore, this study aimed to examine the diagnosis accuracy of ESR1 mutation detection by cell-free DNA in breast cancer patientsthrough a systematic review and comprehensive meta-analysis.
METHODS: PubMed, Embase, and Web of Science databases were searched up to 6 April 2022. Diagnostic studies on ESR1 measurement by cfDNA, which was confirmed using the tumour tissue biopsy, have been included in the study. The sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were considered to analyse the data.
RESULTS: Out of 649 papers, 13 papers with 15 cohorts, including 389 participants, entered the meta-analyses. The comprehensive meta-analysis indicated a high sensitivity (75.52, 95% CI 60.19-90.85), specificity (88.20, 95% CI 80.99-95.40), and high accuracy of 88.96 (95% CI 83.23-94.69) for plasma ESR1. We also found a moderate PPV of 56.94 (95% CI 41.70-72.18) but a high NPV of 88.53 (95% CI 82.61-94.44). We also found an NLR of 0.443 (95% CI 0.09-0.79) and PLR of 1.60 (95% CI 1.20-1.99).
CONCLUSIONS: This systematic review and comprehensive meta-analysis reveal that plasma cfDNA testing exhibits high sensitivity and specificity in detecting ESR1 mutations in breast cancer patients. This suggests that the test could be a valuable diagnostic tool. It may serve as a dependable and non-invasive technique for identifying ESR1 mutations in breast cancer patients. However, more extensive research is needed to confirm its prognostic value.

OBJECTIVE: Estrogen receptor-positive (ER+) breast cancer represents about 80% of cases, tamoxifen is the election neoadjuvant chemotherapy. However, a large percentage of patients develop chemoresistance, compromising recovery. Clinical evidence suggests that high plasmatic levels of low-density lipoproteins (LDL) could promote cancer progression. The present study analyzed the effect of LDL on the primary plasmatic active Tamoxifen\'s metabolites resistance acquisition, 4-hydroxytamoxifen (4OH-Tam) and 4-hydroxy-N-desmethyl-tamoxifen (endoxifen), in breast cancer ERα + cells (MCF-7).
METHODS: Two resistant cellular variants, MCF-7Var-H and MCF-7Var-I, were generated by a novel strategy and their phenotype features were evaluated. Phenotypic assessment was performed by MTT assays, cytometry, immunofluorescence microscopy, zymography and protein expression analysis.
RESULTS: MCF-7Var-H, generated only with tamoxifen metabolites, showed a critical down-regulation in hormone receptors, augmented migration capacity, metalloprotease 9 extracellular medium excretion, and a mesenchymal morphology in contrast with native MCF-7, suggesting the transition towards Triple-negative breast cancer (TNBC) phenotype. In contrast, MCF-7Var-I which was generated in a high LDL media, showed only a slight upregulation in ER and other less noticeable metabolic adaptations. Results suggest a potential role of transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in phenotypic differences observed among variants.
CONCLUSIONS: LDL high or low concentrations during Tamoxifen´s metabolites chemoresistance acquisition leads to different cellular mechanisms related to chemoresistance. A novel adaptative cellular response associated with Nrf2 activity could be implicated.

Biological signal transduction networks are central to information processing and regulation of gene expression across all domains of life. Dysregulation is known to cause a wide array of diseases, including cancers. Here I introduce self-consistent signal transduction analysis, which utilizes genome-scale -omics data (specifically transcriptomics and/or proteomics) in order to predict the flow of information through these networks in an individualized manner. I apply the method to the study of endocrine therapy in breast cancer patients, and show that drugs that inhibit estrogen receptor α elicit a wide array of antitumoral effects, and that their most clinically-impactful ones are through the modulation of proliferative signals that control the genes GREB1, HK1, AKT1, MAPK1, AKT2, and NQO1. This method offers researchers a valuable tool in understanding how and why dysregulation occurs, and how perturbations to the network (such as targeted therapies) effect the network itself, and ultimately patient outcomes.

Cancer development and progression are generally associated with gene dysregulation, often resulting from changes in the transcription factor (TF) sequence or expression. Identifying key TFs involved in cancer gene regulation provides a framework for potential new therapeutics. This study presents a large-scale cancer gene TF-DNA interaction network, as well as an extensive promoter clone resource for future studies. Highly connected TFs bind to promoters of genes associated with either good or poor cancer prognosis, suggesting that strategies aimed at shifting gene expression balance between these two prognostic groups may be inherently complex. However, we identified potential for oncogene-targeted therapeutics, with half of the tested oncogenes being potentially repressed by influencing specific activators or bifunctional TFs. Finally, we investigate the role of intrinsically disordered regions within the key cancer-related TF ESR1 in DNA binding and transcriptional activity, and found that these regions can have complex trade-offs in TF function. Altogether, our study broadens our knowledge of the TFs involved in cancer gene regulation and provides a valuable resource for future studies and therapeutics.

Dual-targeting chromatin regulation and DNA damage repair signaling presents a promising avenue for cancer therapy. Applying rational drug design, we synthesized a potent dual-targeting small molecule, SP-1-303. Here, we report SP-1-303 as a class I isoform selective histone deacetylase (HDAC) inhibitor and an activator of the ataxia-telangiectasia mutated protein (ATM). In vitro enzymatic assays demonstrated selective inhibition of HDAC1 and HDAC3. Cellular growth inhibition studies show that SP-1-303 differentially inhibits growth of estrogen receptor positive breast cancer (ER+ BC) cells with effective growth inhibition concentrations (EC50) for MCF-7 and T47D cells ranging from 0.32 to 0.34 μM, compared to 1.2-2.5 μM for triple negative breast cancer cells, and ~12 μM for normal breast epithelial cells. Western analysis reveals that SP-1-303 decreases estrogen receptor alpha (ER-α) expression and increases p53 protein expression, while inducing the phosphorylation of ATM and its substrates, BRCA1 and p53, in a time-dependent manner in ER+ BC cells. Pharmacokinetic evaluation demonstrates an area under the curve (AUC) of 5227.55 ng/ml × h with an elimination half-life of 1.26 h following intravenous administration in a rat model. Collectively, SP-1-303 emerges as a novel second generation class I (HDAC1 and HDAC3) selective HDAC inhibitor, and ATM activator, capable of modulating ER expression, and inhibiting growth of ER+ BC cells. Combined targeting of class I HDACs and ATM by SP-1-303 offers a promising therapeutic approach for treating ER+ breast cancers and supports further preclinical evaluation.

Perimenopause significantly impacts women\'s health globally, often managed with hormone replacement therapy (HRT) despite the associated risks. This study explores a novel alternative exosome therapy, aimed at stimulating estrogen production in ovarian tissues, thus offering a potential non-hormonal treatment for perimenopausal symptoms. Employing ex vivo methodologies, ovarian cortex specimens from perimenopausal women were treated with exosomes derived from human umbilical cord mesenchymal stem cells and cultured under specific conditions (patent number: PCT/US2022/073467). The exosomes were produced under cyclic guanosine monophosphate (cGMP) conditions, ensuring high safety standards. Estrogen levels were quantified using enzyme-linked immunosorbent assay (ELISA), and gene expression changes in estrogen and follicle-stimulating hormone (FSH) receptors were assessed via quantitative polymerase chain reaction (PCR). Immunohistochemistry (IHC) was utilized to evaluate cellular proliferation and apoptotic markers. The results indicated a significant increase in estrogen levels and estrogen receptor-alpha (Erα) expression in treated tissues compared to controls. Additionally, a decrease in apoptotic markers and an increase in cellular proliferation markers were observed. These findings suggest that exosome therapy can effectively enhance estrogen production and modulate receptor sensitivity in perimenopausal ovarian tissues. This approach could serve as a safer alternative to HRT, aligning with the body\'s natural regulatory mechanisms and potentially offering a more effective treatment option for managing perimenopausal symptoms.

Glyphosate, the active ingredient of several broad-spectrum herbicides, is widely used throughout the world, although many adverse effects are known. Among these, it has been recognized as an endocrine disruptor. This work aimed to test the effects and potential endocrine disrupting action of glyphosate on PNT1A human prostate cells, an immortalized non-tumor epithelial cell line, possessing both ERα and ERβ estrogen receptors. The results showed that glyphosate induces cytotoxicity, mitochondrial dysfunction, and rapid activation of ERα and ERβ via nuclear translocation. Molecular analysis indicated a possible involvement of apoptosis in glyphosate-induced cytotoxicology. The apoptotic process could be attributed to alterations in mitochondrial metabolism; therefore, the main parameters of mitochondrial functionality were investigated using the Seahorse analyzer. Impaired mitochondrial function was observed in glyphosate-treated cells, with reductions in ATP production, spare respiratory capacity, and proton leakage, along with increased efficiency of mitochondrial coupling. Finally, the results of immunofluorescence analysis demonstrated that glyphosate acts as an estrogen disruptor determining the nuclear translocation of both ERs. Nuclear translocation occurred independent of dose, faster than the specific hormone, and persisted throughout treatment. In conclusion, the results collected show that in non-tumor prostate cells glyphosate can cause cell death and acts as a xenoestrogen, activating estrogen receptors. The consequent alteration of hormonal functions can have negative effects on the reproductive health of exposed animals, compromising their fertility.