Ribavirin restores ESR1 gene expression and tamoxifen sensitivity in ESR1 negative breast cancer cell lines

Dulaglutide as a demethylating agent to improve the outcome of breast cancer

Background: Dulaglutide emerged as a promising therapeutic option for diabetes mellitus Type 2 (DM2). Aims: Owing to epigenetic similarities between the pathophysiology of DM2 and breast cancer (BC), we investigated the antitumor effect of dulaglutide. Materials & methods: To investigate the effect of dulaglutide, we analyzed the expression of methylated gene promoter regions in BC (ESR1, CDH1 and ADAM33). Results: Dulaglutide increased the expression of ESR1, CDH1 and ADAM33 up to fourfold in the MDA-MB-231 lineage by demethylating the gene promoter regions. This effect was translated to in vivo antitumoral activity and revealed significant tumor inhibition by combining the half-dose of methotrexate with dulaglutide. Conclusion: This therapy may mitigate the severe side effects commonly associated with chemotherapy.

Regulation of Eukaryotic Translation Initiation Factor 4E as a Potential Anticancer Strategy

Eukaryotic translation initiation factors (eIFs) are highly expressed in cancer cells, especially eIF4E, the central regulatory node driving cancer cell growth and a potential target for anticancer drugs. eIF4E-targeting strategies primarily focus on inhibiting eIF4E synthesis, interfering with eIF4E/eIF4G interactions, and targeting eIF4E phosphorylation and peptide inhibitors. Although some small-molecule inhibitors are in clinical trials, no eIF4E inhibitors are available for clinical use. We provide an overview of the regulatory mechanisms of eIF4E and summarize the progress in developing and discovering eIF4E inhibitor strategies. We propose that interference with eIF4E/eIF4G interactions will provide a new perspective for the design of eIF4E inhibitors and may be a preferred strategy.

Harnessing Epigenetics for Breast Cancer Therapy: The Role of DNA Methylation, Histone Modifications, and MicroRNA

Breast cancer exhibits various epigenetic abnormalities that regulate gene expression and contribute to tumor characteristics. Epigenetic alterations play a significant role in cancer development and progression, and epigenetic-targeting drugs such as DNA methyltransferase inhibitors, histone-modifying enzymes, and mRNA regulators (such as miRNA mimics and antagomiRs) can reverse these alterations. Therefore, these epigenetic-targeting drugs are promising candidates for cancer treatment. However, there is currently no effective epi-drug monotherapy for breast cancer. Combining epigenetic drugs with conventional therapies has yielded positive outcomes and may be a promising strategy for breast cancer therapy. DNA methyltransferase inhibitors, such as azacitidine, and histone deacetylase inhibitors, such as vorinostat, have been used in combination with chemotherapy to treat breast cancer. miRNA regulators, such as miRNA mimics and antagomiRs, can alter the expression of specific genes involved in cancer development. miRNA mimics, such as miR-34, have been used to inhibit tumor growth, while antagomiRs, such as anti-miR-10b, have been used to inhibit metastasis. The development of epi-drugs that target specific epigenetic changes may lead to more effective monotherapy options in the future.

A high-throughput drug screen reveals means to differentiate triple-negative breast cancer

Plasticity delineates cancer subtypes with more or less favourable outcomes. In breast cancer, the subtype triple-negative lacks expression of major differentiation markers, e.g., estrogen receptor α (ERα), and its high cellular plasticity results in greater aggressiveness and poorer prognosis than other subtypes. Whether plasticity itself represents a potential vulnerability of cancer cells is not clear. However, we show here that cancer cell plasticity can be exploited to differentiate triple-negative breast cancer (TNBC). Using a high-throughput imaging-based reporter drug screen with 9 501 compounds, we have identified three polo-like kinase 1 (PLK1) inhibitors as major inducers of ERα protein expression and downstream activity in TNBC cells. PLK1 inhibition upregulates a cell differentiation program characterized by increased DNA damage, mitotic arrest, and ultimately cell death. Furthermore, cells surviving PLK1 inhibition have decreased tumorigenic potential, and targeting PLK1 in already established tumours reduces tumour growth both in cell line- and patient-derived xenograft models. In addition, the upregulation of genes upon PLK1 inhibition correlates with their expression in normal breast tissue and with better overall survival in breast cancer patients. Our results indicate that differentiation therapy based on PLK1 inhibition is a potential alternative strategy to treat TNBC.

Synthesis of ribavirin 1,2,3- and 1,2,4-triazolyl analogs with changes at the amide and cytotoxicity in breast cancer cell lines

We report the synthesis and cytotoxicity in MCF-7 and MDA-MB-231 breast cancer cells of novel 1,2,3- and 1,2,4-triazolyl analogs of ribavirin. We modified ribavirin's carboxamide moiety to test the effects of lipophilic groups. 1-β-D-Ribofuranosyl-1H-1,2,3-triazoles were prepared using Click Chemistry, whereas an unprecedented application of a prior 1,2,4-triazole ring synthesis was used for 1-β-D-ribofuranosyl-1H-1,2,4-triazole analogs. Though cytotoxicity was mediocre and there was no correlation with lipophilicity, we discovered that a structurally similar concentrative nucleoside transporter 2 (CNT2) inhibitor was modestly cytotoxic (MCF-7 IC₅₀ of 42 µM). These syntheses could be used to efficiently investigate variation in the nucleobase.

Berberine Inhibits MDA-MB-231 Cells as an Agonist of G Protein-Coupled Estrogen Receptor 1

G protein-coupled estrogen receptor 1 (GPER1) is a potential therapeutic target for treating triple-negative breast cancers (TNBC). However, modulators for GPER1 that can be used to treat TNBC have not appeared. Berberine (BBR) is a bioactive isoquinoline alkaloid with high oral safety. In recent years, BBR has shown an inhibitory effect on TNBC tumors such as MDA-MB-231, but the molecular target remains unclear, which hinders related clinical research. Our work proved that BBR is a modulator of GPER1 that can inhibit cell viability, migration, and autophagy of MDA-MB-231 cells. The inhibitory effect of BBR on MDA-MB-231 cells has a dependence on estrogen levels. Although BBR promoted the proteasome, which is a major factor in the degradation of GPER1, it could still induce the protein level of GPER1. Correspondingly, the transcription of cellular communication network factor 2 (CCN2) was promoted. BBR could bind to GPER1 directly and change the secondary structure of GPER1, as in the case of 17β-estradiol (E2). In addition, BBR induced not only a high degree of co-localization of GPER1 and microtubule-associated protein 1 light chain 3 (MAP1LC3), but also the accumulation of sequestosome 1 (SQSTM1/p62) by the inhibition of the nuclear translocation of the nuclear factor-kappa B (NF-κB) subunit (RELA/p65), which indicates NF-κB inhibition and anti-cancer effects. This result proved that the promotional effect of BBR on the GPER1/NF-κB pathway was closely related to its inhibitory effect on autophagy, which may serve as a new mechanism by which to explain the inhibitory effect of BBR on MDA-MB-231 cells and expand our understanding of the function of both BBR and GPER1.

A longitudinal sampling study of transcriptomic and epigenetic profiles in patients with thrombocytopenia syndrome

Severe fever with thrombocytopenia syndrome (SFTS) is a novel tick-borne infectious disease caused by a new type of SFTS virus (SFTSV). Here, a longitudinal sampling study is conducted to explore the differences in transcript levels after SFTSV infection, and to characterize the transcriptomic and epigenetic profiles of hospitalized patients. The results reveal significant changes in the mRNA expression of certain genes from onset to recovery. Moreover, m⁶A-seq reveals that certain genes related with immune regulation may be regulated by m⁶A. Besides the routine tests such as platelet counts, serum ALT and AST levels testing, distinct changes in myocardial enzymes, coagulation function, and inflammation are well correlated with the clinical data and sequencing data, suggesting that clinical practitioners should monitor the above indicators to track disease progression and guide personalized treatment. In this study, the transcript changes and RNA modification may lend a fresh perspective to our understanding of the SFTSV and play a significant role in the discovery of drugs for effective treatment of this disease.

The treatment of SARS-CoV2 with antivirals and mitigation of the cytokine storm syndrome: the role of gene expression

In the absence of a vaccine, the treatment of SARS-CoV2 has focused on eliminating the virus with antivirals or mitigating the cytokine storm syndrome (CSS) that leads to the most common cause of death: respiratory failure. Herein we discuss the mechanisms of antiviral treatments for SARS-CoV2 and treatment strategies for the CSS. Antivirals that have shown in vitro activity against SARS-CoV2, or the closely related SARS-CoV1 and MERS-CoV, are compared on the enzymatic level and by potency in cells. For treatment of the CSS, we discuss medications that reduce the effects or expression of cytokines involved in the CSS with an emphasis on those that reduce IL-6 because of its central role in the development of the CSS. We show that some of the medications covered influence the activity or expression of enzymes involved in epigenetic processes and specifically those that add or remove modifications to histones or DNA. Where available, the latest clinical data showing the efficacy of the medications is presented. With respect to their mechanisms, we explain why some medications are successful, why others have failed, and why some untested medications may yet prove useful.

Drug rechanneling: A novel paradigm for cancer treatment

Cancer continues to be one of the leading contributors towards global disease burden. According to NIH, cancer incidence rate per year will increase to 23.6 million by 2030. Even though cancer continues to be a major proportion of the disease burden worldwide, it has the lowest clinical trial success rate amongst other diseases. Hence, there is an unmet need for novel, affordable and effective anti-neoplastic medications. As a result, a growing interest has sparkled amongst researchers towards drug repurposing. Drug repurposing follows the principle of polypharmacology, which states, "any drug with multiple targets or off targets can present several modes of action". Drug repurposing also known as drug rechanneling, or drug repositioning is an economic and reliable approach that identifies new disease treatment of already approved drugs. Repurposing guarantees expedited access of drugs to the patients as these drugs are already FDA approved and their safety and toxicity profile is completely established. Epidemiological studies have identified the decreased occurrence of oncological or non-oncological conditions in patients undergoing treatment with FDA approved drugs. Data from multiple experimental studies and clinical observations have depicted that several non-neoplastic drugs have potential anticancer activity. In this review, we have summarized the potential anti-cancer effects of anti-psychotic, anti-malarial, anti-viral and anti-emetic drugs with a brief overview on their mechanism and pathways in different cancer types. This review highlights promising evidences for the repurposing of drugs in oncology.

Targeting of protein translation as a new treatment paradigm for prostate cancer

PURPOSE OF REVIEW

The current overview will summarize some of the developments in the area of protein translation, including their relation to the therapeutic targeting of prostate cancer.

RECENT FINDINGS

Translational control, mediated by the rate-limiting eukaryotic translation initiation factor 4E (eIF4E), drives selective translation of several oncogenic proteins, thereby contributing to tumor growth, metastasis, and treatment resistance in various cancers, including prostate cancer. As an essential regulatory hub, several oncogenic hyperactive signaling pathways appear to converge on eIF4E to promote tumorigenesis. Several approaches that target the eIF4E-dependent protein translation network are being actively studied, and it is likely that some may ultimately emerge as promising anticancer therapeutics.

SUMMARY

An array of inhibitors has shown promise in targeting specific components of the translational machinery in several preclinical models of prostate cancer. It is hoped that some of these approaches may ultimately have relevance in improving the clinical outcomes of patients with advanced prostate cancer.

Estrogens enhance myoblast differentiation in facioscapulohumeral muscular dystrophy by antagonizing DUX4 activity

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant neuromuscular disorder that is characterized by extreme variability in symptoms, with females being less severely affected than males and presenting a higher proportion of asymptomatic carriers. The sex-related factors involved in the disease are not known. Here, we have utilized myoblasts isolated from FSHD patients (FSHD myoblasts) to investigate the effect of estrogens on muscle properties. Our results demonstrated that estrogens counteract the differentiation impairment of FSHD myoblasts without affecting cell proliferation or survival. Estrogen effects are mediated by estrogen receptor β (ERβ), which reduces chromatin occupancy and transcriptional activity of double homeobox 4 (DUX4), a protein whose aberrant expression has been implicated in FSHD pathogenesis. During myoblast differentiation, we observed that the levels and activity of DUX4 increased progressively and were associated with its enhanced recruitment in the nucleus. ERβ interfered with this recruitment by relocalizing DUX4 in the cytoplasm. This work identifies estrogens as a potential disease modifier that underlie sex-related differences in FSHD by protecting against myoblast differentiation impairments in this disease.

Epigenetic effects of chromatin remodeling agents on organotypic cultures

BACKGROUND

Tumor epigenetic defects are of increasing relevance to clinical practice, because they are 'druggable' targets for cancer therapy using chromatin-remodeling agents (CRAs). New evidences highlight the importance of the microenvironment on the epigenome regulation and the need to use culture models able to preserve tissue morphology, to better understand the action of CRAs. Methods & methods: We studied the epigenetic response induced by culturing and CRAs in a preclinical model, preserving ex vivo the original tissue microenvironment and morphology, assessing different epigenetic signatures. Our overall findings suggest that culturing and CRAs cause heterogeneous effects on the genes methylation; CRAs affect the global DNA methylation and can trigger an active DNA demethylation; the culture induces alterations in the histone deacetylase expression.

CONCLUSION

Despite the limited number of cases, these findings can be considered a proof of concept of the possibility to test CRAs epigenetic effects on ex vivo tissues maintained in their native tissue architecture.

Targeting translation: eIF4E as an emerging anticancer drug target

The translation initiation factor eIF4E mediates a rate-limiting process that drives selective translation of many oncongenic proteins such as cyclin D1, survivin and VEGF, thereby contributing to tumour growth, metastasis and therapy resistance. As an essential regulatory hub in cancer signalling network, many oncogenic signalling pathways appear to converge on eIF4E. Therefore, targeting eIF4E-mediated cap-dependent translation is considered a promising anticancer strategy. This paper reviews the strategies that can be used to target eIF4E, highlighting agents that target eIF4E activity at each distinct level.

Constitutive expression of AhR and BRCA-1 promoter CpG hypermethylation as biomarkers of ERα-negative breast tumorigenesis

Background

Only 5–10 % of breast cancer cases is linked to germline mutations in the BRCA-1 gene and occurs early in life. Conversely, sporadic breast tumors, which represent 90-95 % of breast malignancies, have lower BRCA-1 expression, but not mutated BRCA-1 gene, and tend to occur later in life in combination with other genetic alterations and/or environmental exposures. The latter may include environmental and dietary factors that activate the aromatic hydrocarbon receptor (AhR). Therefore, understanding if changes in expression and/or activation of the AhR are associated with somatic inactivation of the BRCA-1 gene may provide clues for breast cancer therapy.

Methods

We evaluated Brca-1 CpG promoter methylation and expression in mammary tumors induced in Sprague–Dawley rats with the AhR agonist and mammary carcinogen 7,12-dimethyl-benzo(a)anthracene (DMBA). Also, we tested in human estrogen receptor (ER)α-negative sporadic UACC-3199 and ERα-positive MCF-7 breast cancer cells carrying respectively, hyper- and hypomethylated BRCA-1 gene, if the treatment with the AhR antagonist α-naphthoflavone (αNF) modulated BRCA-1 and ERα expression. Finally, we examined the association between expression of AhR and BRCA-1 promoter CpG methylation in human triple-negative (TNBC), luminal-A (LUM-A), LUM-B, and epidermal growth factor receptor-2 (HER-2)-positive breast tumor samples.

Results

Mammary tumors induced with DMBA had reduced BRCA-1 and ERα expression; higher Brca-1 promoter CpG methylation; increased expression of Ahr and its downstream target Cyp1b1; and higher proliferation markers Ccnd1 (cyclin D1) and Cdk4. In human UACC-3199 cells, low BRCA-1 was paralleled by constitutive high AhR expression; the treatment with αNF rescued BRCA-1 and ERα, while enhancing preferential expression of CYP1A1 compared to CYP1B1. Conversely, in MCF-7 cells, αNF antagonized estradiol-dependent activation of BRCA-1 without effects on expression of ERα. TNBC exhibited increased basal AhR and BRCA-1 promoter CpG methylation compared to LUM-A, LUM-B, and HER-2-positive breast tumors.

Conclusions

Constitutive AhR expression coupled to BRCA-1 promoter CpG hypermethylation may be predictive markers of ERα-negative breast tumor development. Regimens based on selected AhR modulators (SAhRMs) may be useful for therapy against ERα-negative tumors, and possibly, TNBC with increased AhR and hypermethylated BRCA-1 gene.

Current and upcoming approaches to exploit the reversibility of epigenetic mutations in breast cancer

DNA methylation and histone modifications are important epigenetic modifications associated with gene (dys)regulation. The epigenetic modifications are balanced by epigenetic enzymes, so-called writers and erasers, such as DNA (de)methylases and histone (de)acetylases. Aberrant epigenetic alterations have been associated with various diseases, including breast cancer. Since aberrant epigenetic modifications are potentially reversible, they might represent targets for breast cancer therapy. Indeed, several drugs have been designed to inhibit epigenetic enzymes (epi-drugs), thereby reversing epigenetic modifications. US Food and Drug Administration approval has been obtained for some epi-drugs for hematological malignancies. However, these drugs have had very modest anti-tumor efficacy in phase I and II clinical trials in breast cancer patients as monotherapy. Therefore, current clinical trials focus on the combination of epi-drugs with other therapies to enhance or restore the sensitivity to such therapies. This approach has yielded some promising results in early phase II trials. The disadvantage of epi-drugs, however, is genome-wide effects, which may cause unwanted upregulation of, for example, pro-metastatic genes. Development of gene-targeted epigenetic modifications (epigenetic editing) in breast cancer can provide a novel approach to prevent such unwanted events. In this context, identification of crucial epigenetic modifications regulating key genes in breast cancer is of critical importance. In this review, we first describe aberrant DNA methylation and histone modifications as two important classes of epigenetic mutations in breast cancer. Then we focus on the preclinical and clinical epigenetic-based therapies currently being explored for breast cancer. Finally, we describe epigenetic editing as a promising new approach for possible applications towards more targeted breast cancer treatment.

Derailed estrogen signaling and breast cancer: an authentic couple

Estrogen or 17β-estradiol, a steroid hormone, plays a critical role in the development of mammary gland via acting through specific receptors. In particular, estrogen receptor-α (ERα) acts as a transcription factor and/or a signal transducer while participating in the development of mammary gland and breast cancer. Accumulating evidence suggests that the transcriptional activity of ERα is altered by the action of nuclear receptor coregulators and might be responsible, at least in part, for the development of breast cancer. In addition, this process is driven by various posttranslational modifications of ERα, implicating active participation of the upstream receptor modifying enzymes in breast cancer progression. Emerging studies suggest that the biological outcome of breast cancer cells is also influenced by the cross talk between microRNA and ERα signaling, as well as by breast cancer stem cells. Thus, multiple regulatory controls of ERα render mammary epithelium at risk for transformation upon deregulation of normal homeostasis. Given the importance that ERα signaling has in breast cancer development, here we will highlight how the activity of ERα is controlled by various regulators in a spatial and temporal manner, impacting the progression of the disease. We will also discuss the possible therapeutic value of ERα modulators as alternative drug targets to retard the progression of breast cancer.