EZH2 regulates expression of FOXC1 by mediating H3K27me3 in breast cancers

Dual-target EZH2 inhibitor: latest advances in medicinal chemistry

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, plays a crucial role in tumor progression by regulating gene expression. EZH2 inhibitors have emerged as promising anti-tumor agents due to their potential in cancer treatment strategies. However, single-target inhibitors often face limitations such as drug resistance and side effects. Dual-target inhibitors, exemplified by EZH1/2 inhibitor HH-2853(28), offer enhanced efficacy and reduced adverse effects. This review highlights recent advancements in dual inhibitors targeting EZH2 and other proteins like BRD4, PARP1, and EHMT2, emphasizing rational design, structure-activity relationships, and safety profiles, suggesting their potential in clinical applications.

Research progress on the regulatory mechanisms of FOXC1 expression in cancers and its role in drug resistance

The Forkhead box C1 (FOXC1) transcription factor is an important member of the FOX family. After initially being identified in triple-negative breast cancer (TNBC) with significant oncogenic function, FOXC1 was subsequently demonstrated to be involved in the development of more than 16 types of cancers. In recent years, increasing studies have focused on the deregulatory mechanisms of FOXC1 expression and revealed that FOXC1 expression was regulated at multiple levels including transcriptional regulation, post-transcription regulation and post-translational modification. Moreover, dysregulation of FOXC1 is also implicated in drug resistance in various types of cancer, especially in breast cancer, which further emphasizes the translational and clinical significance of FOXC1 as a therapeutic target in cancer treatment. This review summarizes recent findings on mechanisms of FOXC1 dysregulation in cancers and its role in chemoresistance, which will help to better understand the oncogenic role of FOXC1, overcome FOXC1-mediated drug resistance and develop targeted therapy for FOXC1 in cancers.

Dual target PARP1/EZH2 inhibitors inducing excessive autophagy and producing synthetic lethality for triple-negative breast cancer therapy

Currently available PARP inhibitors are mainly used for the treatment of BRCA-mutated triple-negative breast cancer (TNBC), with a narrow application range of approximately 15% of patients. Recent studies have shown that EZH2 inhibitors have an obvious effect on breast cancer xenograft models and can promote the sensitivity of ovarian cancer cells to PARP inhibitors. Here, a series of new dual-target PARP1/EZH2 inhibitors for wild-BRCA type TNBC were designed and synthesized. SAR studies helped us identify compound 12e, encoded KWLX-12e, with good inhibitory activity against PARP1 (IC50 = 6.89 nM) and EZH2 (IC50 = 27.34 nM). Meanwhile, KWLX-12e showed an optimal cytotoxicity against MDA-MB-231 cells (IC50 = 2.84 μM) and BT-549 cells (IC50 = 0.91 μM), with no toxicity on normal breast cell lines. KWLX-12e also exhibited good antitumor activity with the TGI value of 75.94%, more effective than Niraparib plus GSK126 (TGI = 57.24%). Mechanistic studies showed that KWLX-12e achieved synthetic lethality indirectly by inhibiting EZH2 to increase the sensitivity to PARP1, and induced cell death by regulating excessive autophagy. KWLX-12e is expected to be a potential candidate for the treatment of TNBC.

Demethylase FTO inhibits the occurrence and development of triple-negative breast cancer by blocking m 6A-dependent miR-17-5p maturation-induced ZBTB4 depletion

Triple-negative breast cancer (TNBC) is a subtype of breast cancer, and its mechanisms of occurrence and development remain unclear. In this study, we aim to investigate the role and molecular mechanisms of the demethylase FTO (fat mass and obesity-associated protein) in TNBC. Through analysis of public databases, we identify that FTO may regulate the maturation of miR-17-5p and subsequently influence the expression of zinc finger and BTB domain-containing protein 4 (ZBTB4), thereby affecting the occurrence and progression of TNBC. We screen for relevant miRNAs and mRNAs from the GEO and TCGA databases and find that the FTO gene may play a crucial role in TNBC. In vitro cell experiments demonstrate that overexpression of FTO can suppress the proliferation, migration, and invasion ability of TNBC cells and can regulate the maturation of miR-17-5p through an m 6A-dependent mechanism. Furthermore, we establish a xenograft nude mouse model and collect clinical samples to further confirm the role and impact of the FTO/miR-17-5p/ZBTB4 regulatory axis in TNBC. Our findings unveil the potential role of FTO and its underlying molecular mechanisms in TNBC, providing new perspectives and strategies for the research and treatment of TNBC.

MicroRNA let-7c-5p Alleviates in Hepatocellular Carcinoma by Targeting Enhancer of Zeste Homolog 2: A Study Intersecting Bioinformatic Analysis and Validated Experiments

Enhancer of zeste homolog 2 (EZH2)gene has a prognostic role in hepatocellular carcinoma (HCC). This study aimed to identify the role of microRNAs (miRNAs) let-7c-5p by targeting EZH2 in HCC. We downloaded gene and miRNA RNA-seq data from The Cancer Genome Atlas (TCGA) database. Differences in EZH2 expression between different groups were analyzed and the association of EZH2 expression with HCC prognosis was detected using Cox regression analysis. The miRNA-EZH2-pathway network was constructed. Dual-luciferase reporter assay was performed to detect the hsa-let-7c-5p-EZH2. Cell proliferation, migration, invasion, and apoptosis were detected by CCK-8, Wound healing, Transwell, and Flow cytometry, respectively. RT-qPCR and Western blot were used to detect the expression of let-7c-5p and EZH2. EZH2 was upregulated in HCC tumors (P < 0.0001). Cox regression analysis showed that TCGA HCC patients with high EZH2 expression levels showed a short survival time [hazard ratio (HR) = 1.677, 95% confidence interval (CI) 1.316-2.137; P < 0.0001]. Seven miRNAs were negatively correlated with EZH2 expression and were significantly downregulated in HCC tumor samples (P < 0.0001), in which hsa-let-7c-5p was associated with prognosis in HCC (HR = 0.849 95% CI 0.739-0.975; P = 0.021). We identified 14 immune cells that showed significant differences in EZH2 high- and low-expression groups. Additionally, let-7c-5p inhibited HCC cell proliferation, migration, and invasion and reversed the promoted effects of EZH2 on HCC cell malignant characteristics. hsa-let-7c-5p-EZH2 significantly suppressed HCC malignant characteristics, which can be used for HCC prognosis.

SND1, a novel co-activator of HIF1α, promotes tumor initiation in PyMT-induced breast tumor

The multifunctional protein staphylococcal nuclease domain-containing protein 1 (SND1) is conserved and has been implicated in several aspects of tumor development, such as proliferation, epithelial-mesenchymal transition, and immune evasion. Despite this, the precise role of SND1 in the initiation and metastasis of mammary gland tumors remains largely unexplored. In this study, we utilized a mouse model of breast tumors induced by polyomavirus middle T antigen (PyMT) to demonstrate that the knockout of SND1 significantly delayed the onset of primary mammary tumor formation induced by PyMT. Histological staining and cytometric analysis were conducted to confirm the reduction of tumor-initiating cells and lung metastasis following depletion of SND1. Additionally, our findings demonstrate that enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), a crucial epigenetic modifier implicated in PyMT-induced breast tumors, serves as an essential mediator of SND1-promoted primary mammary tumor formation. Mechanistic investigations revealed that SND1 functions as a transcriptional co-activator of hypoxia-inducible factor 1 subunit alpha (HIF1α), thereby regulating the downstream target gene EZH2 and promoting tumorigenesis. Overall, this study provides novel insights into the role of SND1 as a co-activator of HIF1α in the acceleration of PyMT-induced spontaneous breast tumor formation through the promotion of EZH2 transcription. The findings provide novel insights into the relationship between SND1 and the formation of tumor-initiating cells.

Simultaneous Delivery of Doxorubicin and EZH2-Targeting siRNA by Vortex Magnetic Nanorods Synergistically Improved Anti-Tumor Efficacy in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), one of the most aggressive types of breast cancer, currently lacks a targeted therapy and has a high clinical recurrence rate. The present study reports an engineered magnetic nanodrug based on Fe3 O4 vortex nanorods coated with a macrophage membrane loaded with doxorubicin (DOX) and Enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) siRNA. This novel nanodrug displays excellent tissue penetration and preferential tumor accumulation. More importantly, it significantly increases tumor suppression compared to chemotherapy, suggesting the synergistic activity of the combination of doxorubicin and EZH2-inhibition. Importantly, owing to tumor-targeted delivery, nanomedicine shows an excellent safety profile after systemic delivery, unlike conventional chemotherapy. In summary, chemotherapy and gene therapy are combined into a novel magnetic nanodrug carrying doxorubicin and EZH2 siRNA, which shows promising clinical application potential in TNBC therapy.

EZH1/2 as targets for cancer therapy

The enhancer of zeste homolog 2 (EZH2) and its highly related homolog EZH1 are considered to be epigenetic silencing factors, and they play key roles in the growth and differentiation of cells as the core components of polycomb repressive complex 2 (PRC2). EZH1 and EZH2 are known to have a role in human malignancies, and alterations in these two genes have been implicated in transformation of human malignancies. Inhibition of EZH1/2 has been shown to result in tumor regression in humans and has been studied and evaluated in the preclinical setting and in multiple clinical trials at various levels. Our work thus contributes to the understanding of the relationship between regulatory molecules associated with EZH1/2 proteins and tumor progression, and may provide new insights for mechanism-based EZH1/2-targeted therapy in tumors.

The role of FOXC1/FOXCUT/DANCR axis in triple negative breast cancer: a bioinformatics and experimental approach

BACKGROUND

Triple-negative breast cancer (TNBC) is the most challenging subtype of breast cancer and does not benefit from the existing targeted therapies. In the present study, we used bioinformatics and experimental approaches to assess the genes that are somehow involved in the epithelial-mesenchymal transition (EMT) pathway which may explain the invasive features of TNBC.

METHOD AND RESULTS

We analyzed five GEO datasets consisting of 657 breast tumors by GEO2R online software to achieve common differentially expressed genes (DEGs) between TNBC and non-TNBC tumors. The expression of the selected coding and non-coding genes was validated in 100 breast tumors, including fifty TNBC and fifty non-TNBC samples, using quantitative Real-Time PCR (qRT-PCR). The bioinformatics approach resulted in a final DEG list consisting of ten upregulated and seventeen downregulated genes (logFC ≥|1| and P < 0.05). Co-expression network construction indicated the FOXC1 transcription factor as a central hub node. Considering the notable role of FOXC1 in EMT, the expression levels of FOXC1-related lncRNAs, lnc-FOXCUT and lnc-DANCR, were also evaluated in the studied tumors. The results of qRT-PCR confirmed notable upregulation of FOXC1, lnc-FOXCUT, and lnc-DANCR in TNBC tissues compared to non-TNBC samples (P < 0.0001, P = 0.0005, and P = 0.0008, respectively). Moreover, ROC curve analysis revealed the potential biomarker role of FOXC1 in TNBC samples.

CONCLUSION

Present study suggested that the deregulation of FOXC1/lnc-FOXCUT/lnc-DANCR axis may contribute to the aggressive features of triple-negative breast tumors. Therefore, this axis may be considered as a new probable therapeutic target in the treatment of TNBC.

DZNep promotes mouse bone defect healing via enhancing both osteogenesis and osteoclastogenesis

Background

Enhancer of zeste homolog 2 (EZH2) is a novel oncogene that can specifically trimethylate the histone H3 lysine 27 (H3K27me3) to transcriptionally inhibit the expression of downstream tumor-suppressing genes. As a small molecular inhibitor of EZH2, 3-Deazaneplanocin (DZNep) has been widely studied due to the role of tumor suppression. With the roles of epigenetic regulation of bone cells emerged in past decades, the property and molecular mechanism of DZNep on enhancing osteogenesis had been reported and attracted a great deal of attention recently. This study aims to elucidate the role of DZNep on EZH2-H3K27me3 axis and downstream factors during both osteoclasts and osteoblasts formation and the therapeutic possibility of DZNep on bone defect healing.

Methods

Bone marrow-derived macrophages (BMMs) cells were cultured, and their responsiveness to DZNep was evaluated by cell counting kit-8, TRAP staining assay, bone resorption assay, podosome actin belt. Bone marrow-derived mesenchymal stem cells (BMSC) were cultured and their responsiveness to DZNep was evaluated by cell counting kit-8, ALP and AR staining assay. The expression of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), Wnt signaling pathway was determined by qPCR and western blotting. Mouse bone defect models were created, rescued by DZNep injection, and the effectiveness was evaluated by X-ray and micro-CT and histological staining.

Results

Consistent with the previous study that DZNep enhances osteogenesis via Wnt family member 1(Wnt1), Wnt6, and Wnt10a, our results showed that DZNep also promotes osteoblasts differentiation and mineralization through the EZH2-H3K27me3-Wnt4 axis. Furthermore, we identified that DZNep promoted the receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast formation via facilitating the phosphorylation of IKKα/β, IκB, and subsequently NF-κB nuclear translocation, which credit to the EZH2-H3K27me3-Foxc1 axis. More importantly, the enhanced osteogenesis and osteoclastogenesis result in accelerated mice bone defect healing in vivo.

Conclusion

DZNep targeting EZH2-H3K27me3 axis facilitated the healing of mice bone defect via simultaneously enhancing osteoclastic bone resorption and promoting osteoblastic bone formation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02670-6.

EZH2 as a new therapeutic target in brain tumors: Molecular landscape, therapeutic targeting and future prospects

Brain tumors are responsible for high mortality and morbidity worldwide. The brain tumor treatment depends on identification of molecular pathways involved in progression and malignancy. Enhancer of zeste homolog 2 (EZH2) has obtained much attention in recent years in field of cancer therapy due to its aberrant expression and capacity in modulating expression of genes by binding to their promoter and affecting methylation status. The present review focuses on EZH2 signaling in brain tumors including glioma, glioblastoma, astrocytoma, ependymomas, medulloblastoma and brain rhabdoid tumors. EZH2 signaling mainly participates in increasing proliferation and invasion of cancer cells. However, in medulloblastoma, EZH2 demonstrates tumor-suppressor activity. Furthermore, EZH2 can regulate response of brain tumors to chemotherapy and radiotherapy. Various molecular pathways can function as upstream mediators of EZH2 in brain tumors including lncRNAs and miRNAs. Owing to its enzymatic activity, EZH2 can bind to promoter of target genes to induce methylation and affects their expression. EZH2 can be considered as an independent prognostic factor in brain tumors that its upregulation provides undesirable prognosis. Both anti-tumor agents and gene therapies such as siRNA have been developed for targeting EZH2 in cancer therapy.

Therapeutically Targeting Cancers That Overexpress FOXC1: A Transcriptional Driver of Cell Plasticity, Partial EMT, and Cancer Metastasis

Metastasis accounts for more than 90% of cancer related mortality, thus the most pressing need in the field of oncology today is the ability to accurately predict future onset of metastatic disease, ideally at the time of initial diagnosis. As opposed to current practice, what would be desirable is that prognostic, biomarker-based detection of metastatic propensity and heightened risk of cancer recurrence be performed long before overt metastasis has set in. Without such timely information it will be impossible to formulate a rational therapeutic treatment plan to favorably alter the trajectory of disease progression. In order to help inform rational selection of targeted therapeutics, any recurrence/metastasis risk prediction strategy must occur with the paired identification of novel prognostic biomarkers and their underlying molecular regulatory mechanisms that help drive cancer recurrence/metastasis (i.e. recurrence biomarkers). Traditional clinical factors alone (such as TNM staging criteria) are no longer adequately prognostic for this purpose in the current molecular era. FOXC1 is a pivotal transcription factor that has been functionally implicated to drive cancer metastasis and has been demonstrated to be an independent predictor of heightened metastatic risk, at the time of initial diagnosis. In this review, we present our viewpoints on the master regulatory role that FOXC1 plays in mediating cancer stem cell traits that include cellular plasticity, partial EMT, treatment resistance, cancer invasion and cancer migration during cancer progression and metastasis. We also highlight potential therapeutic strategies to target cancers that are, or have evolved to become, “transcriptionally addicted” to FOXC1. The potential role of FOXC1 expression status in predicting the efficacy of these identified therapeutic approaches merits evaluation in clinical trials.

Combination of AZD3463 and DZNep Prevents Bone Metastasis of Breast Cancer by Suppressing Akt Signaling

Osteolysis resulting from osteoclast overactivation is one of the severe complications of breast cancer metastasis to the bone. Previous studies reported that the anti-cancer agent DZNep induces cancer cell apoptosis by activating Akt signaling. However, the effect of DZNep on breast cancer bone metastasis is unknown. We previously found that DZNep enhances osteoclast differentiation by activating Akt. Therefore, we explored the use of the anti-cancer agent AZD3463 (an Akt inhibitor) along with DZNep, as AZD3463 can act as an anti-cancer agent and can also potentially ameliorate bone erosion. We evaluated osteoclast and breast cancer cell phenotypes and Akt signaling in vitro by treating cells with DZNep and AZD3463. Furthermore, we developed a breast cancer bone metastasis animal model in mouse tibiae to further determine their combined effects in vivo. Treatment of osteoclast precursor cells with DZNep alone increased osteoclast differentiation, bone resorption, and expression of osteoclast-specific genes. These effects were ameliorated by AZD3463. The combination of DZNep and AZD3463 inhibited breast cancer cell proliferation, colony formation, migration, and invasion. Finally, intraperitoneal injection of DZNep and AZD3463 ameliorated tumor progression and protected against bone loss. In summary, DZNep combined with AZD3463 prevented skeletal complications and inhibited breast cancer progression by suppressing Akt signaling.