Search

Purpose: Histone deacetylase inhibitors (HDACi) are promising anticancer drugs. Although some HDACi have entered the clinic, the mechanism(s) underlying their tumor selectivity are poorly understood.Experimental Design and Results: Using gene expression analysis, we define a core set of six genes commonly regulated in acute myeloid leukemia (AML) blasts and cell lines. MYC, the most prominently modulated, is preferentially altered in leukemia. Upon HDACi treatment, c-Myc is acetylated at lysine 323 and its expression decreases, leading to TRAIL activation and apoptosis. c-Myc binds to the TRAIL promoter on the proximal GC box through SP1 or MIZ1, impairing TRAIL activation. HDACi exposure triggers TRAIL expression, altering c-Myc-TRAIL binding. These events do not occur in normal cells. Excitingly, this inverse correlation between TRAIL and c-Myc is supported by HDACi treatment ex vivo of AML blasts and primary human breast cancer cells. The predictive value of c-Myc to HDACi responsiveness is confirmed in vivo in AML patients undergoing HDACi-based clinical trials.Conclusions: Collectively, our findings identify a key role for c-Myc in TRAIL deregulation and as a biomarker of the anticancer action of HDACi in AML. The potential improved patient stratification could pave the way toward personalized therapies. Clin Cancer Res; 23(10); 2542–55. ©2016 AACR.

SAHA effects in different cell lines.

Schematic representation of the TRAIL promoter, its analyzed regions and the occupancy of epi-marks analyzed under indicated conditions.

Epigenetic status of the TRAIL promoter region after HDACi exposure.

c-Myc down-regulation modulates DR5 and p21 genes.

SAHA effects in normal cells.

Suppl. Methods

HDACI-specific effects on c-Myc acetylation.

Effects of c-Myc overexpression, p21shRNA and TRAILshRNA (A).

Primer sequence, location and product of amplification size.

HDACi effects in different cell lines.

The shelterin component telomeric repeat-binding factor 2 (TRF2) is an essential regulator of telomere homeostasis and genomic stability. Mutations in the TRF2TRFHdomain physically impair t-loop formation and prevent the recruitment of several factors that promote efficient telomere replication, resulting in a telomeric DNA damage response. Here, we design, synthesize, and biologically test covalent cyclic peptides that irreversibly target the TRF2TRFHdomain. We identify APOD53 as our most promising compound. APOD53 forms a covalent adduct with a reactive cysteine residue present in the TRF2TRFHdomain and induces phenotypes consistent with TRF2TRFHdomain mutants. These include induction of a telomeric DNA damage response in the absence of fusions, increased telomeric replication stress, and impaired recruitment of regulator of telomere elongation helicase 1 (RTEL1) and structure-specific endonuclease subunit (SLX4) to telomeres. We demonstrate that APOD53 impairs cell growth in both a telomerase-positive and an ALT cell line, while sparing the viability of non-cancerous cells. Finally, we find that co-treatment with APOD53 and the G4 stabilizer RHPS4 further exacerbates telomere replication stress.

Chromatin has an extremely flexible structure that allows the fine regulation of gene expression. To orchestrate this process, small chemical modifications are dynamically added or removed on DNA, RNA and histone substrates. Epigenetic modifications govern a plethora of key cellular functions, whose dysregulation contributes to oncogenesis. The interrelationship between (irreversible) genetic mutations and (reversible) epigenetic alterations and how this crosstalk regulates gene expression has long been a major area of interest. Marks modulating the RNA code (epitranscriptome), such as the well-studied N

Metabolism plays a fundamental role in both human physiology and pathology, including pancreatic ductal adenocarcinoma (PDAC) and other tumors. Anabolic and catabolic processes do not only have energetic implications but are tightly associated with other cellular activities, such as DNA duplication, redox reactions, and cell homeostasis. PDAC displays a marked metabolic phenotype and the observed reduction in tumor growth induced by calorie restriction with in vivo models supports the crucial role of metabolism in this cancer type. The aggressiveness of PDAC might, therefore, be reduced by interventions on bioenergetic circuits. In this review, we describe the main metabolic mechanisms involved in PDAC growth and the biological features that may favor its onset and progression within an immunometabolic context. We also discuss the need to bridge the gap between basic research and clinical practice in order to offer alternative therapeutic approaches for PDAC patients in the more immediate future.

96 p.-20 fig.-7 tab., Autophagy is a lysosome dependent cell survival mechanism and is central to the maintenance of organismal homeostasis in both physiological and pathological situations. Targeting autophagy in cancer therapy attracted considerable attention in the past as stress-induced autophagy has been demonstrated to contribute to both drug resistance and malignant progression and recently interest in this area has re-emerged. Unlocking the therapeutic potential of autophagy modulation could be a valuable strategy for designing innovative tools for cancer treatment. Microtubule-targeting agents (MTAs) are some of the most successful anti-cancer drugs used in the clinic to date. Scaling up our efforts to develop new anti-cancer agents, we rationally designed multifunctional agents 5a-l with improved potency and safety that combine tubulin depolymerising efficacy with autophagic flux inhibitory activity. Through a combination of computational, biological, biochemical, pharmacokinetic-safety, metabolic studies and SAR analyses we identified the hits 5i,k. These MTAs were characterised as potent pro-apoptotic agents and also demonstrated autophagy inhibition efficacy. To measure their efficacy at inhibiting autophagy, we investigated their effects on basal and starvation-mediated autophagic flux by quantifying the expression of LC3II/LC3I and p62 proteins in oral squamous cell carcinoma and human leukaemia through western blotting and by immunofluorescence study of LC3 and LAMP1 in a cervical carcinoma cell line. Analogues 5i and 5k, endowed with pro-apoptotic activity on a range of hematological cancer cells (including ex-vivo chronic lymphocytic leukaemia (CLL) cells) and several solid tumor cell lines, also behaved as late-stage autophagy inhibitors by impairing autophagosome-lysosome fusion., This research was funded by the European Union's Horizon 2020 (EU) Research and Innovation Programme under the Marie Sklodowska-Curie grant agreement No.721906-TRACT (TK, SM, MG, NMcC, GO’S, RT, VK, SG, DZ, GC, SB); Tuscany strategic project POR-FSE 2014-2020, ‘Medicina di Precisione e Malattie Rare’(MePreMaRe), (ACE-ESCC) (NR, GC, SB), and by “Epigenetic Hallmarks of Multiple Sclerosis” (acronym Epi-MS) (id:415, Merit Ranking Area ERC LS) in VALERE 2019 Program; V:ALERE 2020 – Progetto competitivo “CIRCE” in risposta al bando D.R. n. 138 del February 17, 2020 Program; Blueprint 282510; EPICHEMBIO CM1406; AIRC-17217; VALERE: Vanvitelli per la Ricerca; Campania Regional Government Technology Platform Lotta alle Patologie Oncologiche: iCURE; Campania Regional Government FASE2: IDEAL. MIUR, Proof of Concept POC01_00043. POR Campania FSE 2014-2020 ASSE III.

Chromatin has an extremely flexible structure that allows the fine regulation of gene expression. To orchestrate this process, small chemical modifications are dynamically added or removed on DNA, RNA, and histone substrates. Epigenetic modifications govern a plethora of key cellular functions, whose dysregulation contributes to oncogenesis. The interrelationship between (irreversible) genetic mutations and (reversible) epigenetic alterations and how this crosstalk regulates gene expression has long been a major area of interest. Marks modulating the RNA code (epitranscriptome), such as the well-studied N6 -methyladenosine (m6 A), are known to influence stability, metabolism, and life cycle of many mRNAs, including cancer-associated transcripts. Together, epigenetic and epitranscriptomic pathways therefore control the entire cellular expression profile and, eventually, cell fate. Recently, previously undescribed crosstalk between these two pathways has started to be unrevealed. For example, m6 A and its effectors cooperate with histone modifications to localize chromatin-modifying complexes to their target regions. Epigenetic marks governing the expression of m6 A factors can also be found at specific genetic loci. m6 A itself can mark noncoding RNAs (including lncRNAs, circRNAs, and miRNAs), influencing their structure, maturation, and function. These interactions affect both cell physiology and pathology. Clear evidence that dysregulation of this network plays a role in cancer has emerged, suggesting a new layer of complexity in the landscape of gene expression. Here, we summarize current knowledge on the interplay between m6 A epitranscriptome and epigenome, focusing on cancer processes. We also discuss strategies to target m6 A machinery for future therapeutic intervention. This article is protected by copyright. All rights reserved.

BackgroundmiRNA-21 is a micro-RNA widely studied for its implications in several biological functions, including apoptosis, inflammation, fibrosis, and metabolism. Interestingly, miRNA-21 is a crucial regulator of developing cardiac diseases, but its role is controversial, and it is necessary to clarify its function in pathophysiological events of diabetic cardiomyopathy. In the present study we clarified the protective role of miRNA-21 at cardiac level and evaluated the involvement of miRNA-21 in high glucose induced-acute and chronic cardiac damage. MethodsHuman ventricular cardiac myoblasts AC16, treated and not with miR-21 inhibitor, were exposed to high glucose (33 mM) for 2 and 7 days, and the expression of fibrosis, inflammation, apoptosis, oxidative stress markers were assessed using western blotting. Further, cardiac energetic metabolism was evaluated by measuring both the expression of glucose transporters and regulators of lipids using western blotting analysis and key mitochondrial function parameters (oxygen consumption rate and proton production rate) using Seahorse technology.ResultsShort-term high glucose treatment induced a significant increase in miR-21 expression (pConclusionIn human cardiomyocytes, the abundance of miR-21 takes part in the first defense mechanism against cardiac insult and its cardioprotective effect depends on the time of exposure to the injury. Moreover, miRNA-21regulates mitochondrial respiration and the ability of cells to select the most appropriate substrate for ATP production in a given environment.

Pin1 catalyzes the cis-trans isomerization of pThr-Pro or pSer-Pro amide bonds of various proteins involved in several physio/pathological processes. In this framework, recent research activity is directed toward the identification of new selective Pin1 inhibitors. Here, we developed a set of peptide-based Pin1 inhibitors. Direct-binding experiments allowed the identification of the peptide-based inhibitor 5 k (methylacetyl-l-alanyl-l-histidyl-l-prolyl-l-phenylalaninate) as a potent ligand of Pin1. Notably, 5 k binds Pin1 with higher affinity than Pin4. The comparative analysis of molecular models of Pin1 and Pin4 with the selected compound gave a rational explanation of the biochemical activity and pinpointed the chemical elements that, if opportunely modified, may further improve inhibitory potency, pharmacological properties, and selectivity of future peptide-based parvulin inhibitors. Since 5 k showed limited cell penetration and no antiproliferative activity, it was conjugated to a polyarginine stretch (R8), known to promote cell penetration of peptides, to obtain the R8-5 k derivative, which displayed antiproliferative effects on cancer cell lines over non-tumor cells. The effect of R8 on cell proliferation was also investigated. This work warrants caution about applying the R8 strategy in the development of cell-penetrating antiproliferative peptides, as it is not inert.

Simple Summary Autophagy is an essential process in cell recycling, and its involvement in cancer has been increasingly recognized in the last few decades. This mechanism acts as a double-edged sword in tumor progression and is known to either block or promote tumorigenesis in a context-specific manner. Its role in determining chemotherapeutic resistance makes it a potential target in cancer treatment. The two autophagic inhibitors hydroxychloroquine and chloroquine are currently used in the clinic but cause several side effects in tumor patients. Since recent studies also show that epigenetic enzymes such as histone deacetylase (HDAC) proteins are able to modulate autophagy, this review focuses on the ability of HDAC6 to actively regulate the autophagic process. We also explore the possibility of using HDAC6 inhibitors as therapeutic agents in adjuvant treatment or in combination with autophagic modulators to trigger this mechanism, thus avoiding the occurrence and effects of chemoresistance. Abstract Autophagy is an essential intracellular catabolic mechanism involved in the degradation and recycling of damaged organelles regulating cellular homeostasis and energy metabolism. Its activation enhances cellular tolerance to various stresses and is known to be involved in drug resistance. In cancer, autophagy has a dual role in either promoting or blocking tumorigenesis, and recent studies indicate that epigenetic regulation is involved in its mechanism of action in this context. Specifically, the ubiquitin-binding histone deacetylase (HDAC) enzyme HDAC6 is known to be an important player in modulating autophagy. Epigenetic modulators, such as HDAC inhibitors, mediate this process in different ways and are already undergoing clinical trials. In this review, we describe current knowledge on the role of epigenetic modifications, particularly HDAC-mediated modifications, in controlling autophagy in cancer. We focus on the controversy surrounding their ability to promote or block tumor progression and explore the impact of HDAC6 inhibitors on autophagy modulation in cancer. In light of the fact that targeted drug therapy for cancer patients is attracting ever increasing interest within the research community and in society at large, we discuss the possibility of using HDAC6 inhibitors as adjuvants and/or in combination with conventional treatments to overcome autophagy-related mechanisms of resistance.

Radiotherapy (RT) is one of the mainstay treatments for prostate cancer (PCa), a highly prevalent neoplasm among males worldwide. About 30% of newly diagnosed PCa patients receive RT with a curative intent. However, biochemical relapse occurs in 20–40% of advanced PCa treated with RT either alone or in combination with adjuvant-hormonal therapy. Epigenetic alterations, frequently associated with molecular variations in PCa, contribute to the acquisition of a radioresistant phenotype. Increased DNA damage repair and cell cycle deregulation decreases radio-response in PCa patients. Moreover, the interplay between epigenome and cell growth pathways is extensively described in published literature. Importantly, as the clinical pattern of PCa ranges from an indolent tumor to an aggressive disease, discovering specific targetable epigenetic molecules able to overcome and predict PCa radioresistance is urgently needed. Currently, histone-deacetylase and DNA-methyltransferase inhibitors are the most studied classes of chromatin-modifying drugs (so-called ‘epidrugs’) within cancer radiosensitization context. Nonetheless, the lack of reliable validation trials is a foremost drawback. This review summarizes the major epigenetically induced changes in radioresistant-like PCa cells and describes recently reported targeted epigenetic therapies in pre-clinical and clinical settings. Supplementary Information The online version contains supplementary material available at 10.1186/s13148-021-01111-8.

We test the validity of a possible schematization of DNA structure and dynamics based on the Chern-Simons theory, that is a topological field theory mostly considered in the context of effective gravity theories. By means of the expectation value of the Wilson Loop, derived from this analogue gravity approach, we find the point-like curvature of genomic strings in KRAS human gene and COVID-19 sequences, correlating this curvature with the genetic mutations. The point-like curvature profile, obtained by means of the Chern-Simons currents, can be used to infer the position of the given mutations within the genetic string. Generally, mutations take place in the highest Chern-Simons current gradient locations and subsequent mutated sequences appear to have a smoother curvature than the initial ones, in agreement with a free energy minimization argument., Comment: 25 Pages. Accepted for publication in European Physicsl Journal Plus

Selenium-containing compounds have emerged as a potentially promising treatment for viral infections and tumor development and dissemination. Selenium per se is often considered as a toxic element with little or no beneficial effects, but considerable advances have been made in the understanding of the complex biology, chemistry and drug delivery of this element, especially when it is included in bioactive molecules. Here, we summarize and critically discuss recent findings in the field of selenium-based applications for the treatment of cancer and viral infections.

A novel technique was demonstrated that overcome important drawbacks to crosslink cells by irradiation with ultrashort UV laser pulses (L-crosslinking). To use this technique coupled to Chromatin ImmunoPrecipitation (ChIP) in a high throughput context, a pre-screening fast method needs to be implemented to set up suitable irradiation conditions of the cell sample for efficient L-crosslinking with no final and long ChIP analysis. Here a fast method is reported where living human cells have been first transfected with a vector coding for Estrogen Receptor {\alpha} (ER{\alpha}), linked to Green Florescent protein (ER{\alpha}-GFP), so that the well-known interaction between the Estrogen Receptor Elements (ERE) region of the cell DNA and the ER{\alpha} protein can be detected by studying the fluorometric response of the irradiated cells. The damage induced to cells by UV irradiation is characterized by looking at DNA integrity, proteins stability and cellular viability. A second novel approach is presented to analyze or re-visit DNA and RNA sequences and their molecular configurations. This approach is based on methods derived from Chern-Simons super-gravity adapted to describe mutations in DNA/RNA strings, as well as interactions between nucleic acids. As a preliminary case we analyze the KRAS human gene sequence and some of its mutations. Interestingly, our model shows how the Chern-Simons current are capable to characterize the mutations within a sequence, in particular giving a quantitative indication of the mutation likelihood., Comment: 33 pages, 5 figures

Epigenetics has achieved a profound impact in the biomedical field, providing new experimental opportunities and innovative therapeutic strategies to face a plethora of diseases. In the rare diseases scenario, Beckwith-Wiedemann syndrome (BWS) is a pediatric pathological condition characterized by a complex molecular basis, showing alterations in the expression of different growth-regulating genes. The molecular origin of BWS is associated with impairments in the genomic imprinting of two domains at the 11p15.5 chromosomal region. The first domain contains three different regions: insulin growth like factor gene (IGF2), H19, and abnormally methylated DMR1 region. The second domain consists of cell proliferation and regulating-genes such as CDKN1C gene encoding for cyclin kinase inhibitor its role is to block cell proliferation. Although most cases are sporadic, about 5–10% of BWS patients have inheritance characteristics. In the 11p15.5 region, some of the patients have maternal chromosomal rearrangements while others have Uniparental Paternal Disomy UPD(11)pat. Defects in DNA methylation cause alteration of genes and the genomic structure equilibrium leading uncontrolled cell proliferation, which is a typical tumorigenesis event. Indeed, in BWS patients an increased childhood tumor predisposition is observed. Here, we summarize the latest knowledge on BWS and focus on the impact of epigenetic alterations to an increased cancer risk development and to metabolic disorders. Moreover, we highlight the correlation between assisted reproductive technologies and this rare disease. We also discuss intriguing aspects of BWS in twinning. Epigenetic therapies in clinical trials have already demonstrated effectiveness in oncological and non-oncological diseases. In this review, we propose a potential “epigenetic-based” approaches may unveil new therapeutic options for BWS patients. Although the complexity of the syndrome is high, patients can be able to lead a normal life but tumor predispositions might impair life expectancy. In this sense epigenetic therapies should have a supporting role in order to guarantee a good prognosis.

Histone Deacetylases (HDACs) are among the most attractive and interesting targets in anticancer drug discovery. The clinical relevance of HDAC inhibitors (HDACIs) is testified by four FDA-approved drugs for cancer treatment. However, one of the main drawbacks of these drugs resides in the lack of selectivity against the different HDAC isoforms, resulting in severe side effects. Thus, the identification of selective HDACIs represents an exciting challenge for medicinal chemists. HDACIs are composed of a cap group, a linker region, and a metal-binding group interacting with the catalytic zinc ion. While the cap group has been extensively investigated, less information is available about the effect of the linker on isoform selectivity. To this aim, in this work, we explored novel linker chemotypes to direct isoform selectivity. A small library of 25 hydroxamic acids with hitherto unexplored linker chemotypes was prepared. In vitro tests demonstrated that, depending on the linker type, some candidates selectively inhibit HDAC1 over HDAC6 isoform or vice versa. Docking calculations were performed to rationalize the effect of the novel linker chemotypes on biologic activity. Moreover, four compounds were able to increase the levels of acetylation of histone H3 or tubulin. These compounds were also assayed in breast cancer MCF7 cells to test their antiproliferative effect. Three compounds showed a significant reduction of cancer proliferation, representing valuable starting points for further optimization.

Epidemiological evidence shows that diabetic patients have an increased cancer risk and a higher mortality rate. Glucose could play a central role in metabolism and growth of many tumor types, and this possible mechanism is supported by the high rate of glucose demand and uptake in cancer. Thus, growing evidence suggests that hyperglycemia contributes to cancer progression but also to its onset. Many mechanisms underlying this association have been hypothesized, such as insulin resistance, hyperinsulinemia, and increased inflammatory processes. Inflammation is a common pathophysiological feature in both diabetic and oncological patients, and inflammation linked to high glucose levels sensitizes microenvironment to tumorigenesis, promoting the development of malignant lesions by altering and sustaining a pathological condition in tissues. Glycemic control is the first goal of antidiabetic therapy, and glucose level reduction has also been associated with favorable outcomes in cancer. Here, we describe key events in carcinogenesis focusing on hyperglycemia as supporter in tumor progression and in particular, related to the role of a specific hypoglycemic drug class, sodium-glucose linked transporters (SGLTs). We also discuss the possible use of SGLT2 inhibitor drugs also as a novel potential cancer therapy. Our meta-analysis showed that SGLT-2 inhibitors were significantly associated with an overall reduced risk of cancer as compared to placebo (RR = 0.35, CI 0.33- 0.37, P = 0. 00) with a particular effectiveness for dapaglifozin and ertuglifozin (RR = 0. 06, CI 0. 06- 0. 07 and RR = 0. 22, CI 0. 18- 0. 26). Network Medicine approaches may advance the possible repurposing of these drugs in patients with concomitant diabetes and cancer.

Two dimensional materials beyond graphene such as MoS2 and WS2 are novel and interesting class of materials whose unique physico-chemical properties can be exploited in applications ranging from leading edge nanoelectronics to the frontiers between biomedicine and biotechnology. To unravel the potential of TMD crystals in biomedicine, control over their production through green and scalable routes in biocompatible solvents is critically important. Furthermore, considering multiple applications of eco-friendly 2D dispersions and their potential impact onto live matter, their toxicity and antimicrobial activity still remain an open issue. Herein, we focus on the current demands of 2D TMDs and produce high-quality, few-layered and defect-free MoS2 nanosheets, exfoliated and dispersed in pure water, stabilized up to three weeks. Hence, we studied the impact of this material on human cells by investigating its interactions with three cell lines: two tumoral, MCF7 (breast cancer) and U937 (leukemia), and one normal, HaCaT (epithelium). We observed novel and intriguing results, exhibiting evident cytotoxic effect induced in the tumor cell lines, absent in the normal cells in the tested conditions. The antibacterial action of MoS2 nanosheets is then investigated against a very dangerous gram negative bacterium, such as two types of Salmonellas: ATCC 14028 and wild-type Salmonella typhimurium. Additionally, concentration and layer-dependent modulation of cytotoxic effect is found both on human cells and Salmonellas.

Histone deacetylase inhibitors (HDACi) are promising anticancer drugs. Although some HDACi have entered the clinic, the mechanism(s) underlying their tumor selectivity are poorly understood. Experimental Design/Results: Using gene expression analysis, we define a core set of 6 genes commonly regulated in acute myeloid leukemia (AML) blasts and cell lines. c-Myc, the most prominently modulated, is preferentially altered in leukemia. Upon HDACi treatment, c-Myc is acetylated at lysine 323 and its expression decreases, leading to TRAIL activation and apoptosis. c-Myc binds to the TRAIL promoter on the proximal GC box through Sp1 or Miz1, impairing TRAIL activation. HDACi exposure triggers TRAIL expression, altering c-Myc-TRAIL binding. These events do not occur in normal cells. Excitingly, this inverse correlation between TRAIL and c-Myc is supported by HDACi treatment ex vivo of AML blasts and primary human breast cancer cells. The predictive value of c-Myc to HDACi responsiveness is confirmed in vivo in AML patients undergoing HDACi-based clinical trials. Purpose: Histone deacetylase inhibitors (HDACi) are promising anticancer drugs. Although some HDACi have entered the clinic, the mechanism(s) underlying their tumor selectivity are poorly understood. Experimental Design and Results: Using gene expression analysis, we define a core set of six genes commonly regulated in acute myeloid leukemia (AML) blasts and cell lines. MYC, the most prominently modulated, is preferentially altered in leukemia. Upon HDACi treatment, c-Myc is acetylated at lysine 323 and its expression decreases, leading to TRAIL activation and apoptosis. c-Myc binds to the TRAIL promoter on the proximal GC box through SP1 or MIZ1, impairing TRAIL activation. HDACi exposure triggers TRAIL expression, altering c-Myc-TRAIL binding. These events do not occur in normal cells. Excitingly, this inverse correlation between TRAIL and c-Myc is supported by HDACi treatment ex vivo of AML blasts and primary human breast cancer cells. The predictive value of c-Myc to HDACi responsiveness is confirmed in vivo in AML patients undergoing HDACi-based clinical trials. Conclusions: Collectively, our findings identify a key role for c-Myc in TRAIL deregulation and as a biomarker of the anticancer action of HDACi in AML. The potential improved patient stratification could pave the way toward personalized therapies.

Simple Summary Despite huge efforts in breast cancer care programs, patient’s survival rates greatly vary. Differences in response to therapy still represent the major challenge for clinicians and biologists. Define new anticancer mechanisms and innovative predictors for resistance could be a valid strategy to permanently defeat breast cancer. Here we propose the epigenetic based reprogramming of breast cancer, which leverages on the crosstalk between miR-181a-5p and Estrogen Receptor α. This simultaneously approach allows to induce miR-181a-5p and reduce the receptor expression, blocking the estrogen-dependent proliferative pathway underlying breast cancer progression. Since the epigenetic approach insists on transcriptional regulation, it is mostly independent of the acquired resistance mechanisms typically induced by prolonged endocrine therapy and therefore can be used as a sensitizer, neoadjuvant, or in combination with the standard in care treatments against breast cancer. Abstract The efficacy and side effects of endocrine therapy in breast cancer (BC) depend largely on estrogen receptor alpha (ERα) expression, the specific drug administered, and treatment scheduling. Although the benefits of endocrine therapy outweigh any adverse effects in the initial stages of BC, later- or advanced-stage tumors acquire resistance to treatments. The mechanisms underlying tumor resistance to therapy are still not well understood, posing a major challenge for BC patient care. Epigenetic regulation and miRNA expression may be involved in the switch from a treatment-sensitive to a treatment-resistant state and could provide a valid therapeutic strategy for ERα negative BC. Here, a hybrid lysine-specific histone demethylase inhibitor, MC3324, displaying selective estrogen receptor down-regulator-like activities in BC, was used to highlight the interplay between epigenetic and ERα signaling. MC3324 anticancer action is mediated by microRNA (miRNA) expression regulation, indicating an innovative function for this molecule. Integrated analysis suggests a crosstalk between estrogen signaling, ERα interactors, miRNAs, and their putative targets. Specifically, miR-181a-5p expression is regulated by MC3324 and has an impact on cellular levels of ERα. A comparison of breast tumor versus healthy mammary tissues confirmed the important role of miR-181a-5p in ERα regulation and points to its putative predictive function in BC therapy.

In breast cancer, Lysine-specific demethylase-1 (LSD1) and other lysine demethylases (KDMs), such as Lysine-specific demethylase 6A also known as Ubiquitously transcribed tetratricopeptide repeat, X chromosome (UTX), are co-expressed and co-localize with estrogen receptors (ERs), suggesting the potential use of hybrid (epi)molecules to target histone methylation and therefore regulate/redirect hormone receptor signaling. Here, we report on the biological activity of a dual-KDM inhibitor (MC3324), obtained by coupling the chemical properties of tranylcypromine, a known LSD1 inhibitor, with the 2OG competitive moiety developed for JmjC inhibition. MC3324 displays unique features not exhibited by the single moieties and well-characterized mono-pharmacological inhibitors. Inhibiting LSD1 and UTX, MC3324 induces significant growth arrest and apoptosis in hormone-responsive breast cancer model accompanied by a robust increase in H3K4me2 and H3K27me3. MC3324 down-regulates ER&alpha, in breast cancer at both transcriptional and non-transcriptional levels, mimicking the action of a selective endocrine receptor disruptor. MC3324 alters the histone methylation of ER&alpha, regulated promoters, thereby affecting the transcription of genes involved in cell surveillance, hormone response, and death. MC3324 reduces cell proliferation in ex vivo breast cancers, as well as in breast models with acquired resistance to endocrine therapies. Similarly, MC3324 displays tumor-selective potential in vivo, in both xenograft mice and chicken embryo models, with no toxicity and good oral efficacy. This epigenetic multi-target approach is effective and may overcome potential mechanism(s) of resistance in breast cancer.