Targeted protein degradation (TPD) represents a revolutionary approach to drug discovery, offering a novel mechanism that outperforms traditional inhibitors. This approach employs small molecule drugs to induce the ubiquitination and subsequent degradation of target protein via the proteasome or lysosomal pathways. Key strategies within TPD include proteolysis targeting chimeras (PROTACs), hydrophobic tag tethering degraders (HyTTDs), and molecular glue degraders (MGDs). PROTACs have been undergone clinical evaluations, MGDs have been used in the clinic, and HyTTDs have shown significant progress in cancer treatment. Each of these strategies presents unique advantages and approaches to target protein degradation. This review summarizes five years of research on PROTACs, HyTTDs, and MGDs, highlighting their design principles, advantages, limitations, and future challenges to provide clear guidance and in-depth insights for advancing drug development.

Chromatin architecture is critical in determining nuclear mechanics. Most studies focus on the mechanical rigidity conferred by chromatin condensation from densely packed heterochromatin, but less is known on how transient chromatin decompaction impinge on nucleus stiffness. Here, we used an array of vertically aligned nanopillars to study nuclear deformability in situ after chromatin decompaction in cells. The nucleus significantly stiffened within 4 h of chromatin decompaction but softened at longer timescales. This acute stiffening of the nucleus was underpinned predominantly by an increase in nucleus volume and nuclear import, and partially by enhanced lamin protein recruitment to the periphery. The coupling between nucleus stiffening and acute chromatin decompaction was observed in low malignancy cancer cell lines (e.g. MCF7, PEO1, A549) but weakened in highly malignant counterparts (e.g. MDA-MB-231, HEYA8, HT1080) due to the capacity to efficiently compact heterochromatin into foci that sustains nucleus deformability required for confined migration. Our work signals how rapid chromatin remodeling is a physiologically relevant pathway to modulate nucleus mechanics and cell migration behavior.

Triple-negative breast cancer (TNBC) is an aggressive subtype characterized by limited targeted therapies and high recurrence rates. While immune checkpoint inhibitors (ICIs) have shown promise, their efficacy as monotherapy is limited. Clinically, ICIs demonstrate significant benefit primarily when combined with chemotherapy, particularly in the neoadjuvant setting for early-stage TNBC, which yields superior outcomes compared to adjuvant therapy. This review elucidates the tumor immunological principles underlying these observations. We discussed how the suppressive tumor microenvironment (TME), progressive T cell exhaustion, and associated epigenetic scarring constrain ICI monotherapy effectiveness. Crucially, we highlight the immunological advantages of the neoadjuvant approach: the presence of the primary tumor provides abundant antigens, and intact tumor-draining lymph nodes (TDLNs) act as critical sites for ICI-mediated priming and expansion of naïve and precursor exhausted T cells. This robust activation within TDLNs enhances systemic anti-tumor immunity and expands the T cell repertoire, a process less effectively achieved in the adjuvant setting after tumor resection. These mechanisms provide a strong rationale for the improved pathological complete response (pCR) rates and event-free survival observed with neoadjuvant chemoimmunotherapy, as demonstrated in trials like KEYNOTE-522. We further explore the implications for adjuvant therapy decisions based on treatment response, the challenges of ICI resistance, the need for predictive biomarkers, management of immune-related adverse events (irAEs), and future therapeutic directions. Understanding the dynamic interplay between chemotherapy, ICIs, T cells, and the TME, particularly the role of TDLNs in the neoadjuvant context, is essential for optimizing immunotherapy strategies and improving outcomes for patients with TNBC.

Tissue-based biomarkers that identify women with increased breast cancer risk are needed for cancer prevention. Enhancer of zeste 2 (EZH2) and fatty acid synthase (FASN) are associated with breast cancer aggressiveness, but their expression in normal breast tissues and association with breast cancer risk factors are unclear. Further, there is a need to characterize healthy breast tissue cohorts for unbiased biomarker evaluation. In this study, we employed the Susan G. Komen healthy volunteer tissue bank to evaluate EZH2 and FASN expression and their relationship to breast cancer risk factors. Normal breast core biopsies from 40 healthy donors with low or high Gail scores (<11 or >20, respectively) and normal or obese body mass index (BMI, <25 kg/m 2 or >30 kg/m 2 , respectively) were stained for H&E, EZH2, and FASN and scored independently and blindly using the Allred method. We analyzed the associations between EZH2 and FASN with Gail score, BMI, menopausal status, hormone replacement therapy (HRT), and family history of breast cancer. None of the donors had BRCA1/2 mutations or developed breast cancer after 5 to 9 years. We found that premenopausal women had significantly higher expression of FASN and that EZH2 was higher with increasing Gail risk scores, compared with postmenopausal women. In postmenopausal women, increased EZH2 expression was associated with >5 years of HRT compared with <1 year or no HRT. No associations were found with BMI. This study provides validation of a healthy breast tissue cohort and initial characterization of EZH2 and FASN and their associations with breast cancer risk factors.

Enhancer of zeste homolog 2 (EZH2) is highly expressed in triple-negative breast cancer (TNBC) and induces massive histone modification via trimethylation at lysine 27 of histone H3 (H3K27me3). The expression level of programmed death ligand 1 (PD-L1) is crucial for determining the indications for immune checkpoint inhibitors in patients with TNBC. This study aimed to clarify the regulatory roles of EZH2 and H3K27me3 in the PD-L1 expression in TNBC cells.

The change in the expression of PD-L1 at mRNA and protein levels was investigated by establishing an EZH2-knockdown MDA-MB-231 cell line using siRNA followed by RT-qPCR and western blotting analyses. Localization of the PD-L1 protein was assessed using immunofluorescence. Chromatin immunoprecipitation (ChIP) assays were performed to investigate the histone methylation status of PD-L1 promoter regions. The correlation among PD-L1, EZH2, and H3K27me3 protein expressions was explored in 57 patients with TNBC through immunohistochemistry.

Knockdown of EZH2 restored the PD-L1 expression and localization of PD-L1 protein in the cellular membrane. ChIP assay revealed that the knockdown of EZH2 diminished H3K27 trimethylation and enhanced H3K4 trimethylation in the promoter region of PD-L1. Immunohistochemical analysis of TNBC specimens reflected an inverse correlation between PD-L1 expression and H3K27me3 nuclear positivity; however, no correlation between H3K27me3 status and EZH2 expression was observed.

The downregulation of EZH2 can potentially enhance the efficacy of immune checkpoint inhibitors in patients with TNBC and may provide a new therapeutic strategy.

Enhancer of zeste homolog 2 (EZH2), an epigenetic regulator that primarily inhibits downstream gene expression by tri-methylating histone H3, which is usually overexpressed in tumors and participates in many processes such as tumor occurrence and development, invasion, migration, drug resistance, and anti-tumor immunity as an oncogene, making it an important biomarker in cancer therapy. Collectively, several transcription factors and RNAs cooperate to facilitate the elevated expression of EZH2 in cancer. Although the significance of blocking EZH2 in cancer for inhibiting cancer progression is widely recognized, the clinical application of EZH2 inhibitors continues to encounter numerous challenges. In this review, drawing upon our comprehensive understanding of the factual underpinnings of EZH2's role in cancer, we aim to clarify the crucial importance of targeting EZH2 in cancer treatment. Furthermore, we summarize the current research landscape surrounding targeted EZH2 inhibitors and offer insights into potential future applications of these inhibitors.

Recognition of methylarginine marks by effector proteins ("readers") is a critical link between arginine methylation and various cellular processes. Recently, we identified methylation of AKT1 at arginine-391 (R391), but the reader for this methylation has yet to be characterized. Here, we show that bromodomain-containing protein 9 (BRD9), a reader of acetylated lysine, unexpectedly recognizes methylated R391 of AKT1 through an aromatic cage in its bromodomain. Disrupting the methylarginine reader function of BRD9 suppresses AKT activation and tumorigenesis. RNA sequencing data show that BRD9 and AKT coregulate a hallmark transcriptional program in part through enhancer of zeste homolog 2 (EZH2)-mediated methylation of histone-3 lysine-27. We also find that inhibitors of BRD9 and EZH2 display synergistic effects on suppression of cell proliferation and tumor growth. Collectively, our study reveals a previously unknown function of BRD9 and a potential therapeutic strategy for cancer treatment by combining BRD9 and EZH2 inhibitors.

Enhancer of zeste homolog 2 (EZH2) catalyzes H3K27me3, an epigenetic modification linked to gene silencing, and its overexpression contributes to the progression of hematological malignancies. This study compares the efficacy of a conventional EZH2 inhibitor with a PROTAC-based EZH2 degrader in human lymphoma cell lines. Furthermore, we investigate the anti-tumor effects of combining EZH2 degrader with anti-PD-1, an immune checkpoint inhibitor, focusing on immune cell interactions and underlying mechanisms.

The cytotoxic effects of the EZH2 degrader and EZH2 inhibitor were evaluated in Burkitt's, B-cell, cutaneous T-cell, and Hodgkin's lymphoma cell lines. Additionally, the combination therapy of the EZH2 degrader and anti-PD-1 was assessed both in vitro and in a hu-PBMC-CDX mouse model.

We evaluated the effects of an EZH2 degrader on seven lymphoma cell lines and observed significant reductions in cell viability compared to EZH2 inhibitor, particularly in Burkitt's lymphoma cell lines. EZH2 degrader treatment reduced EZH2 and c-Myc expression, induced G2/M cell cycle arrest, and increased apoptosis markers, including cleaved caspase-3 and cleaved PARP. Furthermore, Burkitt's lymphoma is a PD-L1 negative tumor; however, treatment with the EZH2 degrader resulted in a slight increase in PD-L1 expression. Combining EZH2 degrader with anti-PD-1 significantly enhanced anti-tumor effects compared to monotherapy. In vivo studies using a humanized lymphoma mouse model demonstrated a synergistic anti-tumor effect of EZH2 degrader and anti-PD-1, which was attributed to apoptosis-related pathways.

These findings aim to provide insights into the therapeutic potential of targeting EZH2 in combination with immune checkpoint inhibitors for improved treatment of lymphomas.

EZH2 forms the PRC2 complex with SUZ12 and EED. As a crucial catalytic subunit of PRC2, EZH2 modifies histone H3K27 via its SET domain, resulting in chromatin condensation and suppressing the transcription of related target genes. EZH2 not only functions in PRC2-dependent transcriptional repression but can also activate gene expression in PRC2-independent circumstances or regulate the activity of downstream genes via its own activating mutations. On the basis of the critical role of EZH2 in cancer, the development of inhibitors targeting EZH2 provides a new strategy for cancer therapy.

The purpose of this review is to summarize the molecular mechanisms of EZH2 inhibitors and emphasize the research progress on EZH2 inhibitors published in the patent literature in recent years. The literature and patent databases of PubMed, Web of Science, SCIFinder, WIPO, USPTO, EPO, and CNIPA were combined to search for more effective EZH2 inhibitors.

Recently, a wide range of structurally diverse EZH2 inhibitors, particularly EZH2 degraders, have been identified. These EZH2 modulators have demonstrated significant potential in treating various diseases, with cancer being a primary focus. The development of small molecules targeting EZH2 with distinct pharmacological effects is poised with numerous opportunities.

Polycomb Repressive Complex 2 (PRC2) is a central regulator of gene expression via the trimethylation of histone H3 on lysine 27. This epigenetic modification plays a crucial role in maintaining cell identity and controlling differentiation, while its dysregulation is closely linked to cancer progression. PRC2 silences tumor suppressor genes, promoting cell proliferation, metastasis, epithelial-mesenchymal transition, and cancer stem cell plasticity. Enhancement of zeste homolog 2 (EZH2) overexpression or gain-of-function mutations have been observed in several cancers, including lymphoma, breast, and prostate cancers, driving aggressive tumor behavior and drug resistance. In addition to EZH2, other PRC2 components, such as embryonic ectoderm development (EED) and suppressor of zeste 12, are essential for complex stability and function. EED, in particular, enhances EZH2 activity and has emerged as a therapeutic target. Inhibitors like MAK683 and EED226 disrupt EED's ability to maintain PRC2 activity, thereby reducing H3K27me3 levels and reactivating tumor suppressor genes. Valemetostat, a dual inhibitor of both EZH2 and EED, has shown promising results in aggressive cancers like diffuse large B-cell lymphoma and small-cell lung cancer, underlining the therapeutic potential of targeting multiple PRC2 components. PRC2's role extends beyond gene repression, as it contributes to metabolic reprogramming in tumors, regulating glycolysis and lipid synthesis to fuel cancer growth. Furthermore, PRC2 is implicated in chemoresistance, particularly by modulating DNA damage response and immune evasion. Tazemetostat, a selective EZH2 inhibitor, has demonstrated significant clinical efficacy in EZH2-mutant cancers, such as non-Hodgkin lymphomas and epithelioid sarcoma. However, the compensatory function of enhancer of zeste homolog 1 (EZH1) in some cancers requires dual inhibition strategies, as seen with agents like UNC1999 and Tulmimetostat, which target both EZH1 and EZH2. Given PRC2's multifaceted role in cancer biology, its inhibition represents a promising avenue for therapeutic intervention. The continued development of PRC2 inhibitors and exploration of their use in combination with standard chemotherapy or immunotherapy has great potential for improving patient outcomes in cancers driven by PRC2 dysregulation.

Gray hair, widely regarded as a hallmark of aging. While gray hair is associated with aging, reversing this trait through gene targeting does not alter the fundamental biological processes of aging. Similarly, certain oncogenes (such as CXCR4, MMP-related genes, etc.) can serve as markers of tumor behavior, such as malignancy or prognosis, but targeting these genes alone may not lead to tumor regression. We pioneered the name of this class of genes as "phenotypic genes". Historically, cancer genetics research has focused on tumor driver genes, while genes influencing cancer phenotypes have been relatively overlooked. This review explores the critical distinction between driver genes and phenotypic genes in cancer, using the MAPK and PI3K/AKT/mTOR pathways as key examples. We also discuss current research techniques for identifying driver and phenotypic genes, such as whole-genome sequencing (WGS), RNA sequencing (RNA-seq), RNA interference (RNAi), CRISPR-Cas9, and other genomic screening methods, alongside the concept of synthetic lethality in driver genes. The development of these technologies will help develop personalized treatment strategies and precision medicine based on the characteristics of relevant genes. By addressing the gap in discussions on phenotypic genes, this review significantly contributes to clarifying the roles of driver and phenotypic genes, aiming at advancing the field of targeted cancer therapy.

Mutations in the tumor suppressor genes BRCA1 and BRCA2 are associated with the triple-negative breast cancer phenotype, particularly aggressive and hard-to-treat tumors lacking estrogen, progesterone, and human epidermal growth factor receptor 2. This research aimed to understand the metabolic and genetic links behind BRCA1 and BRCA2 mutations and investigate their relationship with effective therapies. Using the Cytoscape software, two networks were generated through a bibliographic analysis of articles retrieved from the PubMed-NCBI database. We identified 98 genes deregulated by BRCA mutations, and 24 were modulated by therapies. In particular, BIRC5, SIRT1, MYC, EZH2, and CSN2 are influenced by BRCA1, while BCL2, BAX, and BRIP1 are influenced by BRCA2 mutation. Moreover, the study evaluated the efficacy of several promising therapies, targeting only BRCA1/BRCA2-mutated cells. In this context, CDDO-Imidazolide was shown to increase ROS levels and induce DNA damage. Similarly, resveratrol decreased the expression of the anti-apoptotic gene BIRC5 while it increased SIRT1 both in vitro and in vivo. Other specific drugs were found to induce apoptosis selectively in BRCA-mutated cells or block cell growth when the mutation occurs, i.e., 3-deazaneplanocin A, genistein or daidzein, and PARP inhibitors. Finally, over-representation analysis on the genes highlights ferroptosis and proteoglycan pathways as potential drug targets for more effective treatments.

Triple-negative breast cancer (TNBC) remains a leading cause of cancer associated deaths in women owing to its highly metastatic potential and limited treatment options. Recent studies have shown that expression of proteins associated with epigenetic regulation of gene expression are associated with metastatic relapse, however targeting epigenetic regulatory proteins has not resulted in effective therapies for TNBC in the clinic. The ABL tyrosine kinases promote metastasis of breast cancer cells in mouse models. However, a role of ABL kinases in the regulation of epigenetic processes in solid tumor metastasis remains unexplored. Here we show that inactivation of ABL kinases in bone metastatic TNBC cells led to a significant enrichment in gene signatures associated with the PRC2 protein complex, revealing a functional link between ABL kinases and the PRC2 complex. ABL inactivation promotes EZH2-T487 phosphorylation through the regulation of a FAK-CDK1 signaling axis. We find that phosphorylated EZH2 T487 or a phosphomimic EZH2 T487D mutant exhibit increased binding to non-canonical binding partners of EZH2 including c-MYC and ZMYND8. Notably, we identify a therapeutic vulnerability in TNBC cells whereby combination treatment with ABL allosteric inhibitors and EZH2 inhibitors elicits a synergistic decrease in TNBC cell survival in vitro, and impairs TNBC metastasis, prolonging survival of tumor-bearing mice treated with the combination therapy.

ABL Kinases indirectly impact EZH2 catalytic activity by blocking a signaling cascade that leads to changes in the phosphorylation, protein interactions, and function of the PRC2 catalytic component EZH2 in TNBC.

Background: Medullary thyroid cancer (MTC) is a heterogeneous disease. While the International MTC Grading System (IMTCGS) provides baseline risk stratification, it lacks therapeutic relevance. In several cancers, EZH2 overexpression harbors an adverse prognosis, with several EZH2 inhibitors undergoing investigation. This study validated the IMTCGS and examined the prognostic value of EZH2 and other biomarkers. Methods: Clinical data were collected and MTC specimens were retrospectively reviewed and morphologically assessed. Immunohistochemistry (IHC) of Ki-67 allowed IMTCGS validation. IHC of EZH2, PD-L1 and PSMA was evaluated on a tissue microarray (TMA). Results: Of 64 MTCs, the median tumor size was 28 mm (IQR 15-40). Coagulative necrosis, ≥5 mitoses, and Ki-67 ≥ 5% was seen in nineteen (30%), three (5%) and seven (11%) cases. Median Ki-67 was 0.9% (IQR 0.4-2.1). Forty-three (67%) and twenty-one (33%) were classified as IMTCGS low- and high-risk, respectively. High-risk tumors were associated with lower distant metastasis-free survival (DMFS) (HR 5.651, p = 0.017), locoregional recurrence-free survival (LRFS) (HR 18.323, p < 0.001) and disease-specific survival (DSS) (HR 10.001, p = 0.002), but not with overall survival (OS) (HR 2.109, p = 0.146). EZH2 expression was identified in 39/46 (85%) cases on the TMA. An expression of ≥10% (9/46, 20%) was predictive for DMFS (HR 4.747, p = 0.030), LRFS (HR 4.242, 0.039), DSS (HR 19.736, p < 0.001) and OS (HR 8.386, p = 0.004). PD-L1 and PSMA had no prognostic value. Conclusions: This study validates the prognostic value of the IMTCGS and identifies EZH2 as a novel prognostic biomarker in MTC patients. The therapeutic potential of EZH2 warrants further investigation in larger cohorts.

Polycomb repressive complex 2 (PRC2) is responsible for depositing H3K27me3 and plays essential roles in gene silencing during development and cancer. Meanwhile, the nuclear exosome targeting (NEXT) complex facilitates the degradation of numerous noncoding RNAs in the nucleoplasm. Here we find that the functional deficiency of the NEXT complex leads to an overall decrease in H3K27me3 levels. Specifically, ZCCHC8 depletion results in significant upregulation of nascent long noncoding RNAs (lncRNAs) containing G-quadruplex (G4) and U-Rich motifs (G4/U-Rich lncRNAs). The G4 motif binds to EZH2, blocking the chromatin recruitment of PRC2, while the U-Rich motif is specifically recognized by the NEXT complex for RNA exosome-mediated degradation. In tumor tissues with high ZCCHC8 expression in clear cell renal cell carcinoma (ccRCC) and lung adenocarcinoma (LUAD) patients, the NEXT complex excessively degrades nascent G4/U-Rich lncRNAs. Consequently, PRC2 core subunits are released and recruited to neighboring genomic loci, resulting in increased H3K27me3 levels and downregulation of adjacent genes, including tumor suppressors like SEMA5A and ARID1A. Notably, the EZH2 inhibitor Tazemetostat (EPZ-6438) exhibits greater sensitivity in cells with higher ZCCHC8 expression. Altogether, our findings demonstrate a novel mechanism that the NEXT complex regulates H3K27me3 levels by degrading nascent G4/U-Rich lncRNAs in cancer cells.

Myelomatous bone disease is a complication characterized by lytic bone lesions, reduced bone formation, bone pain, and increased fracture risk. Understanding these underlying mechanisms is crucial for developing effective therapeutic approaches. Here we show the role of enhancer of zeste homolog 2 (EZH2) in bone lesions induced by myeloma cells. Our research reveals that cytokines produced by myeloma-associated adipocytes activate the expression of EZH2 in myeloma cells. Furthermore, we find that EZH2 forms a transcriptional repression complex with transcription factor AP2α. This complex promotes trimethylation at lysine 27 of histone H3 (H3K27me3) in the promoter region of the tumor suppressor gene EMP1, resulting in transcriptional silencing. EMP1 silencing leads to increased myeloma cell proliferation and the concomitant secretion of osteolytic cytokines that contribute to bone destruction. Importantly, EZH2 inhibitors effectively treat myeloma-induced osteolytic lesions. Thus, targeting EZH2 represents a potential therapeutic strategy for preventing and managing myeloma bone disease.

Viral mimicry refers to an active antiviral response triggered by the activation of endogenous retroviruses (ERVs), usually manifested by the formation of double-stranded RNA (dsRNA) and activation of the cellular interferon response, which activates the immune system and produces anti-tumor effects. Epigenetic studies have shown that epigenetic modifications (e.g. DNA methylation, histone modifications, etc.) play a crucial role in tumorigenesis, progression, and treatment resistance. Particularly, alterations in DNA methylation may be closely associated with the suppression of ERVs expression, and treatment by demethylation may restore ERVs activity and thus strengthen the tumor immune response. Therefore, we propose that viral mimicry can induce immune responses in the tumor microenvironment by activating the expression of ERVs, and that epigenetic alterations may play a key regulatory role in this process. In this paper, we review the intersection of viral mimicry, epigenetics and tumor immunotherapy, and explore the possible interactions and synergistic effects among the three, aiming to provide a new theoretical basis and potential strategies for cancer immunotherapy.

Phyllodes tumors (PTs) are rare breast tumors showing overlapping features with fibroadenomas (FAs). Diagnosis on small biopsies is challenging. New diagnostic markers are needed. Here we evaluated immunohistochemical staining of histone 3 trimethyl-lysine-27 (H3K27me3) as a diagnostic and prognostic marker in a series of PTs. Surgically removed PTs at our institution (September 1990 and July 2022) and control FAs. Tissue micro-arrays (4 cores, 2 mm Ø) stained with H3K27me3, and scored with QuPath-derived H-score. Fisher exact test, Mann-Whitney U-test and chi-squared test used for group comparison. ROC analysis applied to define cutoffs. Cox proportional hazards models were used for assessing disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS) in PTs. We included 81 patients with PTs and 44 patients with FAs. QuPath-derived H-scores of stromal H3K27me3 were statically significantly lower in PTs than in FAs (p < 0.001). We identified exploratory cutoffs to discriminate FAs from benign and malignant PTs (AUC = 0.78 and 0.73, respectively). No associations between DFS, OS, or DSS and H3K27me3 expression were found. H3K27me3 expression differs between FAs and PTs, indicating potential as diagnostic marker, but it is not predictive for DFS, OS or DSS in PTs. Further validation is needed.

Cisplatin (CDDP) resistance has been established to significantly impact Bladder Cancer (BCa) therapy. On the other hand, the crucial regulatory involvement of SIRT7 and EZH2 in bladder cancer development is well known. Herein, the collaborative regulatory roles and underlying mechanisms of SIRT7 and EZH2 in CDDP resistance in bladder cancer were explored. Immunohistochemistry (IHC) and Western Blot (WB) analyses were used to assess the expression levels of SIRT7/EZH2 and RND3 in bladder cancer tissues, normal ureteral epithelial cells, and bladder cancer cell lines. Furthermore, the impact of various treatments on of UMUC3 cell proliferation and CDDP sensitivity was assessed using CCK-8 assays, plate cloning assays, and flow cytometry analysis. Additionally, the levels of H3K18ac and H3K27me3 at the promoter region of the RND3 gene, the binding abilities of SIRT7 and EZH2, and the succinylation level of the EZH2 protein were examined using ChIP-qPCR assays, CO-IP assays, and IP assays, respectively. Moreover, in vivo experiments were conducted using a bladder cancer mouse model created by subcutaneously injecting UMUC3 cells into Balb/c nude mice. According to the results, SIRT7 correlated with the sensitivity of bladder cancer cells to both the platinum-based chemotherapy and CDDP. Specifically, SIRT7 could bind to the RND3 promoter, downregulating H3K18ac and RND3, ultimately leading to an increased CDDP sensitivity in UMUC3 cells. Furthermore, EZH2 siRNA could decrease H3K27me3 levels in the RND3 promoter, upregulating RND3. Overall, in the promoter region of the RND3 gene, SIRT7 upregulated H3K27me3 and EZH2 downregulated H3K18ac, leading to a decline in RND3 expression and CDDP sensitivity in bladder cancer cells. Additionally, SIRT7 reduced the succinylation of the EZH2 protein resulting in an EZH2-mediated RND3 downregulation. Therefore, targeting SIRT7 and EZH2 could be a viable approach to enhancing CDDP efficacy in bladder cancer treatment.

Among women, breast cancer is one of the most prevalent cancers. The disease has a complex etiology, with multiple biological pathways contributing to its development. As insulin signaling has mitogenic effects, glucose is a necessary cellular metabolic substrate, and the growth and metastasis of breast cancer are closely related to cellular glucose metabolism. Anti-diabetic medications have drawn increased attention as a potential treatment for breast cancer. Metformin lowers cancer incidence and death rates in patients with type 2 diabetes, according to epidemiologic studies. Preclinical studies conducted in vivo and in vitro offer fascinating new insights into the cellular mechanisms underlying metformin oncostatic action. We present an overview of the mechanisms of anticancer effects of metformin and discuss its potential function as an adjuvant in the treatment of breast cancer.

Among the most significant discoveries from cancer genomics efforts has been the critical role of epigenetic dysregulation in cancer development and progression. Studies across diverse cancer types have revealed frequent mutations in genes encoding epigenetic regulators, alterations in DNA methylation and histone modifications, and a dramatic reorganization of chromatin structure. Epigenetic changes are especially relevant to pediatric cancers, which are often characterized by a low rate of genetic mutations. The inherent reversibility of epigenetic lesions has led to an intense interest in the development of epigenetic targeted therapies. Additionally, the recent appreciation of the interplay between the epigenome and immune regulation has sparked interest in combination therapies and synergistic immunotherapy approaches. Further, the recent appreciation of epigenetic variability as a driving force in cancer evolution has suggested new roles for epigenetic therapies in limiting plasticity and resistance. Here, we review recent progress and emerging directions in the development of epigenetic targeted therapeutics and their promise across the landscape of childhood cancers.

Polycomb repressive complex 2 (PRC2) is known to regulate gene expression and chromatin structure as it methylates H3K27, resulting in gene silencing. Studies have shown that PRC2 has dual functions in oncogenesis that allow it to function as both an oncogene and a tumor suppressor. Because of this, nuanced strategies are necessary to promote or inhibit PRC2 activity therapeutically. Given the therapeutic vulnerabilities and associated risks in oncological applications, a structured literature review on PRC2 was conducted to showcase similar cofactor competitor inhibitors of PRC2. Key inhibitors such as Tazemetostat, GSK126, Valemetostat, and UNC1999 have shown promise for clinical use within various studies. Tazemetostat and GSK126 are both highly selective for wild-type and lymphoma-associated EZH2 mutants. Valemetostat and UNC1999 have shown promise as orally bioavailable and SAM-competitive inhibitors of both EZH1 and EZH2, giving them greater efficacy against potential drug resistance. The development of other PRC2 inhibitors, particularly inhibitors targeting the EED or SUZ12 subunit, is also being explored with the development of drugs like EED 226. This review aims to bridge gaps in the current literature and provide a unified perspective on promising PRC2 inhibitors as therapeutic agents in the treatment of lymphomas and solid tumors.

Enhancer of zeste homolog 2 (EZH2) is a methyltransferase involved in cell cycle regulation, cell differentiation, and cell death and plays a role in modulating the immune response. Although it mainly functions by catalyzing the tri-methylation of H3 histone on K27 (H3K27), to inhibit the transcription of target genes, EZH2 can directly methylate several transcription factors or form complexes with them, regulating their functions. EZH2 expression/activity is often dysregulated in cancer, contributing to carcinogenesis and immune escape, thereby representing an important target in anti-cancer therapy. This review summarizes some of the mechanisms through which EZH2 regulates the expression and function of tumor suppressor genes and oncogenic molecules such as STAT3, mutant p53, and c-Myc and how it modulates the anti-cancer immune response. The influence of posttranslational modifications on EZH2 activity and stability and the possible strategies leading to its inhibition are also reviewed.

Despite remarkable progress in Pediatric Acute Myeloid Leukemia (pAML) treatments, the relapsed disease remains difficult to treat, making it pertinent to identify novel biomarkers of prognostic/therapeutic significance.

Bone marrow samples from 21 pAML patients were analyzed using single cell RNA sequencing, functional assays with ARMH1 knockdown and overexpression were performed in leukemia cell lines to evaluate impact on proliferation and migration, and chemotherapy sensitivity. Mitochondrial function was assessed via Seahorse assay, ARMH1 interacting proteins were studied using co-immunoprecipitation. Bulk RNA-seq was performed on ARMH1knockdown and over expressing cell lines to evaluate the pathways and networks impacted by ARMH1.

Our data shows that ARMH1, a novel cancer-associated gene, is highly expressed in the malignant blast cells of multiple pediatric hematologic malignancies, including AML, T/B-ALL, and T/B-MPAL. Notably, ARMH1 expression is significantly elevated in blast cells of patients who relapsed or have a high-risk cytogenetic profile (MLL) compared to standard-risk (RUNX1, inv (16)). ARMH1 expression is also significantly correlated with the pediatric leukemia stem cell score of 6 genes (LSC6) associated with poor outcomes. Perturbation of ARMH1 (knockdown and overexpression) in leukemia cell lines significantly impacted cell proliferation and migration. The RNA-sequencing analysis on multiple ARMH1 knockdown and overexpressing cell lines established an association with mitochondrial fatty acid synthesis and cell cycle pathways.The investigation of the mitochondrial matrix shows that pharmacological inhibition of a key enzyme in fatty acid synthesis regulation, CPT1A, resulted in ARMH1 downregulation. ARMH1 knockdown also led to a significant reduction in CPT1A and ATP production as well as Oxygen Consumption Rate. Our data indicates that downregulating ARMH1 impacts cell proliferation by reducing key cell cycle regulators such as CDCA7 and EZH2. Further, we also established that ARMH1 is a key physical interactant of EZH2, associated with multiple cancers.

Our findings underscore further evaluation of ARMH1 as a potential candidate for targeted therapies and stratification of aggressive pAML to improve outcomes.

DNA repair dysregulation is a key driver of cancer development. Understanding the molecular mechanisms underlying DNA repair dysregulation in cancer cells is crucial for cancer development and therapies. Here, we report that enhancer of zeste homolog 2 (EZH2) directly methylates poly(adenosine diphosphate-ribose) polymerase-1 (PARP-1), an essential enzyme involved in DNA repair, and regulates its activity. Functionally, EZH2-catalyzed methylation represses PARP1 catalytic activity, down-regulates the recruitment of x-ray repair cross-complementing group-1 to DNA lesions and its associated DNA damage repair; on the other hand, it protects the cells from nicotinamide adenine dinucleotide overconsumption upon DNA damage formation. Meanwhile, EZH2-mediated methylation regulates PARP1 transcriptional and oncogenic activity, at least in part, through impairing PARP1-E2F1 interaction and E2F1 transcription factor activity. EZH2 and PARP1 inhibitors synergistically suppress prostate cancer growth. Collectively, our findings uncover an insight of EZH2 functions in fine-tuning PARP1 activity during DNA damage repair and cancer progression, which provides a rationale for combinational targeting EZH2 and PARP1 in cancer.

The methyltransferase enhancer of zeste homolog 2 (EZH2) regulates gene expression, and aberrant EZH2 expression and signaling can drive fibrosis and cancer. However, it is not clear how chemical and mechanical signals are integrated to regulate EZH2 and gene expression. We show that culture of cells on stiff matrices in concert with transforming growth factor (TGF)-β1 promotes nuclear localization of EZH2 and an increase in the levels of the corresponding histone modification, H3K27me3, thereby regulating gene expression. EZH2 activity and expression are required for TGFβ1- and stiffness-induced increases in H3K27me3 levels as well as for morphological and gene expression changes associated with epithelial-mesenchymal transition (EMT). Inhibition of Rho associated kinase (ROCK) proteins or myosin II signaling attenuates TGFβ1-induced nuclear localization of EZH2 and decreases H3K27me3 levels in cells cultured on stiff substrata, suggesting that cellular contractility, in concert with a major cancer signaling regulator TGFβ1, modulates EZH2 subcellular localization. These findings provide a contractility-dependent mechanism by which matrix stiffness and TGFβ1 together mediate EZH2 signaling to promote EMT.

Sinonasal undifferentiated carcinoma (SNUC) is a rare and highly aggressive malignancy originating in the nasal cavity and paranasal sinuses. Its pathogenesis and immune characteristics remain poorly understood.

This study investigates the molecular aspects of SNUC, focusing on tumorigenesis and immunity.

For this purpose, spatial transcriptome analysis was employed to compare the gene expression profiles of SNUC tumor cells with those of normal epithelial cells, as well as to compare tumor-infiltrating immune cells with immune cells from normal, tumor-free tissue areas. For validation, next-generation sequencing tests and clinical sample studies were conducted.

Spatial transcriptome analysis revealed notable upregulation of EZH2 and the histone family gene such as H3C2 (H3-clustered histone 2) in SNUC tumor cells. Additionally, gene set enrichment analysis identified significant activations in the histone deacetylase (HDAC) signaling pathway, histone acetyltransferase (HAT) pathway, polycomb repressive complex 2 (PRC2), and DNA methylation pathways. A notable decrease was observed in downregulated genes and pathways, including the mucin family of protein genes, the keratin protein gene, and the mucin glycosylation pathway. Next-generation sequencing did not reveal specific genetic mutations within these pathways, although mutations such as IDH2 R172S were noted. Clinical SNUC tissues confirmed increased immunoexpression of EZH2 and PRC2 markers. Analysis of tumor immunity revealed a characteristic immune cell signature, with a notable predominance of naïve B cells, macrophages, CD8 memory T cells, and Tregs in the SNUC microenvironment, alongside the increased expression of LAG3 in tumor-infiltrating immune cells.

Our study suggests epigenetic mechanisms, particularly via EZH2, play a crucial role in SNUC carcinogenesis. Furthermore, distinctive immune cell profiles in SNUC point to potential immune-related characteristics of this malignancy.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and has the highest rate of recurrence1. The predominant standard of care for advanced TNBC is systemic chemotherapy with or without immunotherapy; however, responses are typically short lived1,2. Thus, there is an urgent need to develop more effective treatments. Components of the PI3K pathway represent plausible therapeutic targets; more than 70% of TNBCs have alterations in PIK3CA, AKT1 or PTEN3-6. However, in contrast to hormone-receptor-positive tumours, it is still unclear whether or how triple-negative disease will respond to PI3K pathway inhibitors7. Here we describe a promising AKT-inhibitor-based therapeutic combination for TNBC. Specifically, we show that AKT inhibitors synergize with agents that suppress the histone methyltransferase EZH2 and promote robust tumour regression in multiple TNBC models in vivo. AKT and EZH2 inhibitors exert these effects by first cooperatively driving basal-like TNBC cells into a more differentiated, luminal-like state, which cannot be effectively induced by either agent alone. Once TNBCs are differentiated, these agents kill them by hijacking signals that normally drive mammary gland involution. Using a machine learning approach, we developed a classifier that can be used to predict sensitivity. Together, these findings identify a promising therapeutic strategy for this highly aggressive tumour type and illustrate how deregulated epigenetic enzymes can insulate tumours from oncogenic vulnerabilities. These studies also reveal how developmental tissue-specific cell death pathways may be co-opted for therapeutic benefit.

Inactivating mutations in SMARCB1 confer an oncogenic dependency on EZH2 in atypical teratoid rhabdoid tumors (ATRTs), but the underlying mechanism has not been fully elucidated. We found that the sensitivity of ATRTs to EZH2 inhibition (EZH2i) is associated with the viral mimicry response. Unlike other epigenetic therapies targeting transcriptional repressors, EZH2i-induced viral mimicry is not triggered by cryptic transcription of endogenous retroelements, but rather mediated by increased expression of genes enriched for intronic inverted-repeat Alu (IR-Alu) elements. Interestingly, interferon-stimulated genes (ISGs) are highly enriched for dsRNA-forming intronic IR-Alu elements, suggesting a feedforward loop whereby these activated ISGs may reinforce dsRNA formation and viral mimicry. EZH2i also upregulates the expression of full-length LINE-1s, leading to genomic instability and cGAS/STING signaling in a process dependent on reverse transcriptase activity. Co-depletion of dsRNA sensing and cytoplasmic DNA sensing completely rescues the viral mimicry response to EZH2i in SMARCB1-deficient tumors.

Breast cancer is one of the most common malignant tumors in women worldwide. Similarly, Canine mammary tumors (CMTs) are mostly diagnosed as spontaneous diseases in female dogs. Many studies have suggested that CMTs serve as good models for human breast cancer. However, comparative approaches to histone modifications are still lacking. This study aimed to compare the canine mammary tumor Histone H3 lysine 4 trimethylation (H3K4me3) landscape with that in human breast cancer. Our H3K4me3 ChIP-seq data from CMTs revealed a significant enrichment of H3K4me3 in the ALYREF gene promoter in tumor tissues compared to normal tissues. Furthermore, our study and publicly available RNA-sequencing data revealed that ALYREF expression was elevated in malignant tissues and breast cancer cell lines, and its upregulation was associated with poor prognosis in humans. Depletion of ALYREF resulted in changes in cellular phenotypes, including increased proliferation and colony formation, as well as decreased apoptosis. ALYREF increased cell viability and anchorage-independent growth while decreasing apoptosis by regulating the mRNA expression and protein levels of enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), which promotes hormone receptor-positive breast cancer and CMTs via epigenetic modifications. This suggests that ALYREF may function as a contributing factor to malignant transformation in both CMT and human breast cancer.

The existence of cancer stem cells (CSCs) in pancreatic ductal adenocarcinoma (PDAC) is considered to be the key factor for metastasis and chemoresistance. Thus, novel therapeutic strategies for eradicating CSCs are urgently needed. Here we aimed to explore the role of KLF15 in stemness and the feasibility of using KLF15 to inhibit CSCs and improve chemotherapy sensitivity in PDAC. In this study, we report that KLF15 is negatively associated with poor survival and advanced pathological staging of PDAC. Moreover, tumorous KLF15 suppresses the stemness of PDAC by promoting the degradation of Nanog, and KLF15 directly interacts with Nanog, inhibiting interaction between Nanog with USP21. We also demonstrate that the KLF15/Nanog complex inhibit the stemness in vivo and in PDX cells. Tazemetostat suppresses stemness and sensitizes PDAC cells to gemcitabine by promoting KLF15 expression in PDAC. In summary, the findings of our study confirm the value of KLF15 level in diagnosis and prognosis of PDAC, it is the first time to explore the inhibition role of KLF15 in stemness of PDAC and the regulation mechanism of Nanog, contributing to provide a new therapeutic strategy that using Tazemetostat sensitizes PDAC cells to gemcitabine by promoting KLF15 expression for PDAC.

Metaplastic breast carcinomas (mBrCA) are a highly aggressive subtype of triple-negative breast cancer with histologic evidence of epithelial-to-mesenchymal transition and aberrant differentiation. Inactivation of the tumor suppressor gene cellular communication network factor 6 (CCN6; also known as Wnt1-induced secreted protein 3) is a feature of mBrCAs, and mice with conditional inactivation of Ccn6 in mammary epithelium (Ccn6-KO) develop spindle mBrCAs with epithelial-to-mesenchymal transition. Elucidation of the precise mechanistic details of how CCN6 acts as a tumor suppressor in mBrCA could help identify improved treatment strategies. In this study, we showed that CCN6 interacts with the Wnt receptor FZD8 and coreceptor LRP6 on mBrCA cells to antagonize Wnt-induced activation of β-catenin/TCF-mediated transcription. The histone methyltransferase EZH2 was identified as a β-catenin/TCF transcriptional target in Ccn6-KO mBrCA cells. Inhibiting Wnt/β-catenin/TCF signaling in Ccn6-KO mBrCA cells led to reduced EZH2 expression, decreased histone H3 lysine 27 trimethylation, and deregulation of specific target genes. Pharmacologic inhibition of EZH2 reduced growth and metastasis of Ccn6-KO mBrCA mammary tumors in vivo. Low CCN6 is significantly associated with activated β-catenin and high EZH2 in human spindle mBrCAs compared with other subtypes. Collectively, these findings establish CCN6 as a key negative regulator of a β-catenin/TCF/EZH2 axis and highlight the inhibition of β-catenin or EZH2 as a potential therapeutic approach for patients with spindle mBrCAs.  Significance: CCN6 deficiency drives metaplastic breast carcinoma growth and metastasis by increasing Wnt/β-catenin activation to upregulate EZH2, identifying EZH2 inhibition as a mechanistically guided treatment strategy for this deadly form of breast cancer.

The tumor microenvironment comprises various cell types and experiences dynamic alterations in physical and mechanical properties as cancer progresses. Intratumoral heterogeneity is associated with poor prognosis and poses therapeutic challenges, and recent studies have begun to identify the cellular mechanisms that contribute to phenotypic diversity within tumors. This review will describe epithelial-mesenchymal (E/M) plasticity and its contribution to phenotypic heterogeneity in tumors as well as how epigenetic factors, such as histone modifications, histone modifying enzymes, DNA methylation, and chromatin remodeling, regulate and maintain E/M phenotypes. This review will also report how mechanical properties vary across tumors and regulate epigenetic modifications and E/M plasticity. Finally, it highlights how intratumoral heterogeneity impacts therapeutic efficacy and provides potential therapeutic targets to improve cancer treatments.

Cistrome-wide association studies (CWAS) are pivotal for identifying genetic determinants of diseases by correlating genetically regulated cistrome states with phenotypes. Traditional CWAS typically develops a model based on cistrome and genotype data to associate predicted cistrome states with phenotypes. The random effect cistrome-wide association study (RECWAS), reevaluates the necessity of cistrome state prediction in CWAS. RECWAS utilizes either a linear model or marginal effect for initial feature selection, followed by kernel-based feature aggregation for association testing is introduced. Through simulations and analysis of prostate cancer data, a thorough evaluation of CWAS and RECWAS is conducted. The results suggest that RECWAS offers improved power compared to traditional CWAS, identifying additional genomic regions associated with prostate cancer. CWAS identified 102 significant regions, while RECWAS found 50 additional significant regions compared to CWAS, many of which are validated. Validation encompassed a range of biological evidence, including risk signals from the GWAS catalog, susceptibility genes from the DisGeNET database, and enhancer-domain scores. RECWAS consistently demonstrated improved performance over traditional CWAS in identifying genomic regions associated with prostate cancer. These findings demonstrate the benefits of incorporating kernel methods into CWAS and provide new insights for genetic discovery in complex diseases.

The progress of cancer treatment methods in the last decade has significantly reduced mortality rate among these patients. Nevertheless, cancer is still recognized as one of the main causes of human deaths. One of the main reasons for the high death rate in cancer patients is the late diagnosis in the advanced tumor stages. Therefore, it is necessary to investigate the molecular biology of tumor progressions in order to introduce early diagnostic markers. MicroRNAs (miRNAs) have an important role in regulating cellular processes associated with tumor progression. Due to the high stability of miRNAs in body fluids, they are widely used as non-invasive markers in the early tumor diagnosis. Since, deregulation of miR-98 has been reported in a wide range of cancers, we investigated the molecular mechanisms of miR-98 during tumor progression. It has been reported that miR-98 mainly inhibits the tumor growth by the modulation of transcription factors and signaling pathways. Therefore, miR-98 can be introduced as a tumor marker and therapeutic target among cancer patients.

Emerging studies support that the polycomb repressive complex 2 (PRC2) regulates phenotypic changes of carcinoma cells by modulating their shifts among metastable states within the epithelial and mesenchymal spectrum. This new role of PRC2 in cancer has been recently proposed to stem from the ability of its catalytic subunit EZH2 to bind and modulate the transcription of mesenchymal genes during epithelial-mesenchymal transition (EMT) in lung cancer cells. Here, we asked whether this mechanism is conserved in other types of carcinomas. By combining TGF-β-mediated reversible induction of epithelial to mesenchymal transition and inhibition of EZH2 methyltransferase activity, we demonstrate that EZH2 represses a large set of mesenchymal genes and favours the residence of breast cancer cells towards the more epithelial spectrum during EMT. In agreement, analysis of human patient samples supports that EZH2 is required to efficiently repress mesenchymal genes in breast cancer tumours. Our results indicate that PRC2 operates through similar mechanisms in breast and lung cancer cells. We propose that PRC2-mediated direct transcriptional modulation of the mesenchymal gene expression programme is a conserved molecular mechanism underlying cell dissemination across human carcinomas.