Recent advancement of HDAC inhibitors against breast cancer

MHY446 induces apoptosis via reactive oxygen species-mediated endoplasmic reticulum stress in HCT116 human colorectal cancer cells

This study investigated the potential of a newly synthesized histone deacetylase (HDAC) inhibitor, MHY446, in inducing cell death in HCT116 colorectal cancer cells and compared its activity with that of suberoylanilide hydroxamic acid (SAHA), a well-known HDAC inhibitor. The results showed that MHY446 increased the acetylation of histones H3 and H4 and decreased the expression and activity of HDAC proteins in HCT116 cells. Additionally, MHY446 was confirmed to bind more strongly to HDAC1 than HDAC2 and inhibit its activity. In vivo experiments using nude mice revealed that MHY446 was as effective as SAHA in inhibiting HCT116 cell-grafted tumor growth. This study also evaluated the biological effects of MHY446 on cell survival and death pathways. The reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) confirmed that ROS play a role in MHY446-induced cell death by reducing poly(ADP-ribose) polymerase cleavage. MHY446 also induced cell death via endoplasmic reticulum (ER) stress by increasing the expression of ER stress-related proteins. NAC treatment decreased the expression of ER stress-related proteins, indicating that ROS mediate ER stress as an upstream signaling pathway and induce cell death. While MHY446 did not exhibit superior HDAC inhibition efficacy compared to SAHA, it is anticipated to provide innovative insights into the future development of therapeutic agents for human CRC by offering novel chemical structure-activity relationship-related information.

Impact of HDAC6-mediated progesterone receptor expression on the response of breast cancer cells to hormonal therapy

Modulation of estrogen receptor (ER) and progesterone receptor (PR) expression, as well as their emerging functional crosstalk, remains a potential approach for enhancing the response to hormonal therapy in breast cancer. Aberrant epigenetic alterations induced by histone deacetylases (HDACs) were massively implicated in dysregulating the function of hormone receptors in breast cancer. Although much is known about the regulation of ER signaling by HDAC, the precise role of HDAC in modulating the expression of PR and its impact on the outcomes of hormonal therapy is poorly defined. Here, we demonstrate the involvement of HDAC6 in regulating PR expression in breast cancer cells. The correlation between HDAC6 and hormone receptors was investigated in patients' tissues by immunohistochemistry (n = 80) and publicly available data (n = 3260) from breast cancer patients. We explored the effect of modulating the expression of HDAC6 as well as its catalytic inhibition on the level of hormone receptors by a variety of molecular analyses, including Western blot, immunofluorescence, Real-time PCR, RNA-seq analysis and chromatin immunoprecipitation. Based on our in-silico and immunohistochemistry analyses, HDAC6 levels were negatively correlated with PR status in breast cancer tissues. The downregulation of HDAC6 enhanced the expression of PR-B in hormone receptor-positive and triple-negative breast cancer (TNBC) cells. The selective targeting of HDAC6 by tubacin resulted in the enrichment of the H3K9 acetylation mark at the PGR-B gene promoter region and enhanced the expression of PR-B. Additionally, transcriptomic analysis of tubacin-treated cells revealed enhanced activity of acetyltransferase and growth factor signaling pathways, along with the enrichment of transcription factors involved in the transcriptional activity of ER, underscoring the crucial role of HDAC6 in regulating hormone receptors. Notably, the addition of HDAC6 inhibitor potentiated the effects of anti-ER and anti-PR drugs mainly in TNBC cells. Together, these data highlight the role of HDAC6 in regulating PR expression and provide a promising therapeutic approach for boosting breast cancer sensitivity to hormonal therapy.

Discovery, lead identification and exploration of potential oxadiazole derivatives in targeting STAT3 as anti-cancer agents

Oxadiazoles an important heterocyclic scaffold of medicinal importance in the field of drug discovery. In the study, a library of oxadiazole based compounds was selected for screening against STAT-3 as anti-cancer target. STAT3 is a potential target of interest in cancer therapy. A total of 544 screened library of compounds was subjected to molecular docking against STAT-3 (6NJS and 6NQU). The compounds with good dock score and binding interations were further subjected to in-silico ADME analysis followed by toxicity estimation. A total of 141 hits were selected against 6NJS and 50 hits against 6NQU and further screened for kinetic properties and drug likeliness. The compounds were screened on the basis of physico-chemical properties, solubility, gastrointestinal absorption, BBB permeability, synthetic accessibility, Lipinski and other violations. Best compounds obtained after ADME analysis were further subjected for toxicity analysis. Carcinogenecity, mutagenicity, Ames and other important parameters were considered for toxicity based screening. The best leads thus obtained (compound 114 and 40) were further subjected to molecular dynamics against the respective target proteins. MD simulations were run to access the stability of C-114 and C-40 along with the dynamic behaviour of both complexes for about 100 ns and shows good stability with the proteins.

Epigenetic modulations in triple-negative breast cancer: Therapeutic implications for tumor microenvironment

Triple-negative breast cancer (TNBC) is an aggressive subtype lacking estrogen receptors, progesterone receptors and lacks HER2 overexpression. This absence of critical molecular targets poses significant challenges for conventional therapies. Immunotherapy, remarkably immune checkpoint blockade, offers promise for TNBC treatment, but its efficacy remains limited. Epigenetic dysregulation, including altered DNA methylation, histone modifications, and imbalances in regulators such as BET proteins, plays a crucial role in TNBC development and resistance to treatment. Hypermethylation of tumor suppressor gene promoters and the imbalance of histone methyltransferases such as EZH2 and histone deacetylases (HDACs) profoundly influence tumor cell proliferation, survival, and metastasis. In addition, epigenetic alterations critically shape the tumor microenvironment (TME), including immune cell composition, cytokine signaling, and immune checkpoint expression, ultimately contributing to immune evasion. Targeting these epigenetic mechanisms with specific inhibitors such as EZH2 and HDAC inhibitors in combination with immunotherapy represents a compelling strategy to remodel the TME, potentially overcoming immune evasion and enhancing therapeutic outcomes in TNBC. This review aims to comprehensively elucidate the current understanding of epigenetic modulation in TNBC, its influence on the TME, and the potential of combining epigenetic therapies with immunotherapy to overcome the challenges posed by this aggressive breast cancer subtype.

Hypoxia-Inducible Factor-Dependent and Independent Mechanisms Underlying Chemoresistance of Hypoxic Cancer Cells

In hypoxic regions of malignant solid tumors, cancer cells acquire resistance to conventional therapies, such as chemotherapy and radiotherapy, causing poor prognosis in patients with cancer. It is widely recognized that some of the key genes behind this are hypoxia-inducible transcription factors, e.g., hypoxia-inducible factor 1 (HIF-1). Since HIF-1 activity is suppressed by two representative 2-oxoglutarate-dependent dioxygenases (2-OGDDs), PHDs (prolyl-4-hydroxylases), and FIH-1 (factor inhibiting hypoxia-inducible factor 1), the inactivation of 2-OGDD has been associated with cancer therapy resistance by the activation of HIF-1. Recent studies have also revealed the importance of hypoxia-responsive mechanisms independent of HIF-1 and its isoforms (collectively, HIFs). In this article, we collate the accumulated knowledge of HIF-1-dependent and independent mechanisms responsible for resistance of hypoxic cancer cells to anticancer drugs and briefly discuss the interplay between hypoxia responses, like EMT and UPR, and chemoresistance. In addition, we introduce a novel HIF-independent mechanism, which is epigenetically mediated by an acetylated histone reader protein, ATAD2, which we recently clarified.

Emerging therapeutic strategies in cancer therapy by HDAC inhibition as the chemotherapeutic potent and epigenetic regulator

In developing new cancer medications, attention has been focused on novel epigenetic medicines called histone deacetylase (HDAC) inhibitors. Our understanding of cancer behavior is being advanced by research on epigenetics, which also supplies new targets for improving the effectiveness of cancer therapy. Most recently published patents emphasize HDAC selective drugs and multitarget HDAC inhibitors. Though significant progress has been made in emerging HDAC selective antagonists, it is urgently necessary to find new HDAC blockers with novel zinc-binding analogues to avoid the undesirable pharmacological characteristics of hydroxamic acid. HDAC antagonists have lately been explored as a novel approach to treating various diseases, including cancer. The complicated terrain of HDAC inhibitor development is summarized in this article, starting with a discussion of the many HDAC isotypes and their involvement in cancer biology, followed by a discussion of the mechanisms of action of HDAC inhibitors, their current level of development, effect of miRNA, and their combination with immunotherapeutic.

Trifluoromethyl quinoline derivative targets inhibiting HDAC1 for promoting the acetylation of histone in cervical cancer cells

Cervical cancer is the leading cause of death among gynecological malignant tumors, especially due to the poor prognosis of patients with advanced tumors due to recurrence, metastasis, and chemotherapy resistance. Therefore, exploring new antineoplastic drugs with high efficacy and low toxicity may bring new expectations in patients with cervical cancer. Natural products and their derivatives exert an antitumor activity. Therefore, in this work, combined with network pharmacology analysis and experimental validation, we investigated the anti-cervical cancer activity and molecular mechanism of a new trifluoromethyl quinoline (FKL) derivative in vivo and in vitro. FKL117 inhibited the proliferation of cervical cancer cells in a dose and time-dependent manner, induced apoptosis in HeLa cells, arrested the cell cycle in the G2/M phase, and regulated the expression of the apoptotic and cell cycle-related proteins Bcl-2, Bax, cyclin B1, and CDC2. We used online databases to obtain HDAC1 as one of the possible targets of FKL117 and the target binding and binding affinity were modeled by molecular docking. The results showed that FKL117 formed a hydrogen bond with HDAC1 and had good binding ability. We found that FKL117 targeted to inhibit the expression and function of HDAC1 and increased the acetylation of histone H3 and H4, which was also confirmed in vivo. The migration of HMGB1 from the nucleus to the cytoplasm further verified the above results. In conclusion, our study suggested that FKL117 might be used as a novel candidate for targeting the inhibition of HDAC1 against cervical cancer.

Unveiling Epigenetic Vulnerabilities in Triple-Negative Breast Cancer through 3D Organoid Drug Screening

Triple-negative breast cancer (TNBC) poses a therapeutic challenge due to its aggressive nature and lack of targeted therapies. Epigenetic modifications contribute to TNBC tumorigenesis and drug resistance, offering potential therapeutic targets. Recent advancements in three-dimensional (3D) organoid cultures, enabling precise drug screening, hold immense promise for identifying novel compounds targeting TNBC. In this study, we established two patient-derived TNBC organoids and implemented a high-throughput drug screening system using these organoids and two TNBC cell lines. Screening a library of 169 epigenetic compounds, we found that organoid-based systems offer remarkable precision in drug response assessment compared to cell-based models. The top 30 compounds showing the highest drug sensitivity in the initial screening were further assessed in a secondary screen. Four compounds, panobinostat, pacritinib, TAK-901, and JIB-04, targeting histone deacetylase, JAK/STAT, histone demethylases, and aurora kinase pathways, respectively, exhibited potent anti-tumor activity in TNBC organoids, surpassing the effect of paclitaxel. Our study highlights the potential of these novel epigenetic drugs as effective therapeutic agents for TNBC and demonstrates the valuable role of patient-derived organoids in advancing drug discovery.

Identification of UBFD1 as a prognostic biomarker and molecular target among estrogen receptor-positive breast cancer

Estrogen receptor (ER)-positive breast cancer (BRCA) is the most commonly diagnosed molecular subtype of BRCA. It is routinely treated with endocrine therapy; however, some patients relapse after therapy and develop drug resistance, resulting in treatment failure. In the present study, we identified markers of ER-positive BRCA and evaluated their putative function in immune infiltration as well as their clinicopathological significance. The ubiquitin family domain containing 1 (UBFD1) protein was associated with the prognosis of ER-positive BRCA patients. Its expression was higher in ER-positive BRCA tissues compared with adjacent nontumor tissues. Patients with higher UBFD1 expression had a poorer prognosis. UBFD1 is an independent risk factor for ER-positive BRCA patients and its function was primarily associated with hormone activity and inflammation. Taken together, UBFD1 is a potential prognostic biomarker and candidate target of ER-positive BRCA.

Deacetylation of Histones and Non-histone Proteins in Inflammatory Diseases and Cancer Therapeutic Potential of Histone Deacetylase Inhibitors

Epigenetic changes play an important role in the pathophysiology of autoimmune diseases such as allergic asthma, multiple sclerosis, lung diseases, diabetes, cystic fibrosis, atherosclerosis, rheumatoid arthritis, and COVID-19. There are three main classes of epigenetic alterations: post-translational modifications of histone proteins, control by non-coding RNA and DNA methylation. Since histone modifications can directly affect chromatin structure and accessibility, they can regulate gene expression levels. Abnormal expression and activity of histone deacetylases (HDACs) have been reported in immune mediated diseases. Increased acetylated levels of lysine residues have been suggested to be related to the overexpression of inflammatory genes. This review focuses on the effect of HDAC modifications on histone and non-histone proteins in autoimmune diseases. Furthermore, we discuss the potential therapeutic effect of HDAC inhibitors (HDACi) used in these diseases.