WDR5 inhibition halts metastasis dissemination by repressing the mesenchymal phenotype of breast cancer cells

The PML1-WDR5 axis regulates H3K4me3 marks and promotes stemness of estrogen receptor-positive breast cancer

The alternative splicing of PML precursor mRNA gives rise to various PML isoforms, yet their expression profile in breast cancer cells remains uncharted. We discovered that PML1 is the most abundant isoform in all breast cancer subtypes, and its expression is associated with unfavorable prognosis in estrogen receptor-positive (ER+) breast cancers. PML depletion reduces cell proliferation, invasion, and stemness, while heterologous PML1 expression augments these processes and fuels tumor growth and resistance to fulvestrant, an FDA-approved drug for ER+ breast cancer, in a mouse model. Moreover, PML1, rather than the well-known tumor suppressor isoform PML4, rescues the proliferation of PML knockdown cells. ChIP-seq analysis reveals significant overlap between PML-, ER-, and Myc-bound promoters, suggesting their coordinated regulation of target gene expression, including genes involved in breast cancer stem cells (BCSCs), such as JAG1, KLF4, YAP1, SNAI1, and MYC. Loss of PML reduces BCSC-related gene expression, and exogenous PML1 expression elevates their expression. Consistently, PML1 restores the association of PML with these promoters in PML-depleted cells. We identified a novel association between PML1 and WDR5, a key component of H3K4 methyltransferase (HMTs) complexes that catalyze H3K4me1 and H3K4me3. ChIP-seq analyses showed that the loss of PML1 reduces H3K4me3 in numerous loci, including BCSC-associated gene promoters. Additionally, PML1, not PML4, re-establishes the H3K4me3 mark on these promoters in PML-depleted cells. Significantly, PML1 is essential for recruiting WDR5, MLL1, and MLL2 to these gene promoters. Inactivating WDR5 by knockdown or inhibitors phenocopies the effects of PML1 loss, reducing BCSC-related gene expression and tumorsphere formation and enhancing fulvestrant's anticancer activity. Our findings challenge the conventional understanding of PML as a tumor suppressor, redefine its role as a promoter of tumor growth in breast cancer, and offer new insights into the unique roles of PML isoforms in breast cancer.

Exploring promising natural compounds for breast cancer treatment: in silico molecular docking targeting WDR5-MYC protein interaction

Cancer is an aberrant differentiation of normal cells, characterized by uncontrolled growth and the potential to acquire invasive and aggressive properties that ultimately lead to metastasis. In the realm of scientific exploration, a multitude of pathways has been investigated and targeted by researchers, among which one specific pathway is recognized as WDR5-MYC. Continuous investigations and research show that WDR5-MYC is a therapeutic target protein. Hence, the discovery of naturally occurring compounds with anticancer properties has been suggested as a rapid and efficient alternative for the development of anticancerous therapeutics. A virtual screening approach was used to identify the most potent compounds from the NP-lib database at the MTiOpenScreen webserver against WDR5-MYC. This process yielded a total of 304 identified compounds. Subsequently, after screening, four potent compounds, namely Estrone (ZINC000003869899), Ethyl-1,2-benzanthracene (ZINC000003157052), Strychnine (ZINC000000119434) and 7H-DIBENZO [C, G] CARBAZOLE (ZINC000001562130), along with a cocrystallized 5-[4-(trifluoromethyl) phenyl]-1H-tetrazole inhibitor (QBP) as a reference ligand, were considered for stringent molecular docking. Thus, each compound exhibited significant docking energy between -8.2 and -7.7 kcal/mol and molecular contacts with essential residue Asn225, Lys250, Ser267 and Lys272 in the active pocket of WDR5-MYC against the QBP inhibitor (the native ligand QBP serves as a reference in the comparative analysis of docked complexes). The results support the potent compounds for drug-likeness and strong binding affinity with WDR5-MYC protein. Further, the stability of the selected compounds was predicted by molecular dynamics simulation (100 ns) contributed by intermolecular hydrogen bonds and hydrophobic interactions. This demonstrates the potential of the selected compounds to be used against breast cancer treatment.Communicated by Ramaswamy H. Sarma.

WD Repeat Domain 5 Inhibitors for Cancer Therapy: Not What You Think

WDR5 is a conserved nuclear protein that scaffolds the assembly of epigenetic regulatory complexes and moonlights in functions ranging from recruiting MYC oncoproteins to chromatin to facilitating the integrity of mitosis. It is also a high-value target for anti-cancer therapies, with small molecule WDR5 inhibitors and degraders undergoing extensive preclinical assessment. WDR5 inhibitors were originally conceived as epigenetic modulators, proposed to inhibit cancer cells by reversing oncogenic patterns of histone H3 lysine 4 methylation-a notion that persists to this day. This premise, however, does not withstand contemporary inspection and establishes expectations for the mechanisms and utility of WDR5 inhibitors that can likely never be met. Here, we highlight salient misconceptions regarding WDR5 inhibitors as epigenetic modulators and provide a unified model for their action as a ribosome-directed anti-cancer therapy that helps focus understanding of when and how the tumor-inhibiting properties of these agents can best be understood and exploited.

The PML1-WDR5 axis regulates H3K4me3 marks and promotes stemness of estrogen receptor-positive breast cancer

The alternative splicing of PML precursor mRNA gives rise to various PML isoforms, yet their expression profile in breast cancer cells remains uncharted. We discovered that PML1 is the most abundant isoform in all breast cancer subtypes, and its expression is associated with unfavorable prognosis in estrogen receptor-positive (ER+) breast cancers. PML depletion reduces cell proliferation, invasion, and stemness, while heterologous PML1 expression augments these processes and fuels tumor growth and resistance to fulvestrant, an FDA-approved drug for ER + breast cancer, in a mouse model. Moreover, PML1, rather than the well-known tumor suppressor isoform PML4, rescues the proliferation of PML knockdown cells. ChIP-seq analysis reveals significant overlap between PML-, ER-, and Myc-bound promoters, suggesting their coordinated regulation of target gene expression, including genes involved in breast cancer stem cells (BCSCs), such as JAG1, KLF4, YAP1, SNAI1, and MYC. Loss of PML reduces BCSC-related gene expression, and exogenous PML1 expression elevates their expression. Consistently, PML1 restores the association of PML with these promoters in PML-depleted cells. We identified a novel association between PML1 and WDR5, a key component of H3K4 methyltransferase (HMTs) complexes that catalyze H3K4me1 and H3K4me3. ChIP-seq analyses showed that the loss of PML1 reduces H3K4me3 in numerous loci, including BCSC-associated gene promoters. Additionally, PML1, not PML4, re-establishes the H3K4me3 mark on these promoters in PML-depleted cells. Significantly, PML1 is essential for recruiting WDR5, MLL1, and MLL2 to these gene promoters. Inactivating WDR5 by knockdown or inhibitors phenocopies the effects of PML1 loss, reducing BCSC-related gene expression and tumorsphere formation and enhancing fulvestrant's anticancer activity. Our findings challenge the conventional understanding of PML as a tumor suppressor, redefine its role as a promoter of tumor growth in breast cancer and offer new insights into the unique roles of PML isoforms in breast cancer.

3D environment controls H3K4 methylation and the mechanical response of the nucleus in acute lymphoblastic leukemia cells

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, and the infiltration of leukemic cells is critical for disease progression and relapse. Nuclear deformability plays a critical role in cancer cell invasion through confined spaces; however, the direct impact of epigenetic changes on the nuclear deformability of leukemic cells remains unclear. Here, we characterized how 3D collagen matrix conditions induced H3K4 methylation in ALL cell lines and clinical samples. We used specific shRNA and chemical inhibitors to target WDR5 (a core subunit involved in H3K4 methylation) and determined that targeting WDR5 reduced the H3K4 methylation induced by the 3D environment and the invasiveness of ALL cells in vitro and in vivo. Intriguingly, targeting WDR5 did not reduce the adhesion or the chemotactic response of leukemia cells, suggesting a different mechanism by which H3K4 methylation might govern ALL cell invasiveness. Finally, we conducted biochemical, and biophysical experiments to determine that 3D environments promoted the alteration of the chromatin, the morphology, and the mechanical behavior of the nucleus in ALL cells. Collectively, our data suggest that 3D environments control an upregulation of H3K4 methylation in ALL cells, and targeting WDR5 might serve as a promising therapeutic target against ALL invasiveness in vivo.

ASH2L, a COMPASS core subunit, is involved in the cell invasion and migration of triple-negative breast cancer cells through the epigenetic control of histone H3 lysine 4 methylation

ASH2L (Absent-Small-Homeotic-2-Like protein) is a core subunit of the COMPASS (COMplex of Proteins ASsociated with Set1) complex, the most notable writer of the methylation of histone H3 lysine 4 (H3K4). The COMPASS complex regulates active promoters or enhancers for gene expression, and its dysfunction is associated with aberrant development and disease. Here, we demonstrated that ASH2L mediated the cell invasion and migration activity of triple-negative breast cancer cells through the interaction with the COMPASS components and the target genomic regions. Transcriptome analysis indicated a potential correlation between ASH2L and the genes involved in inflammatory/immune responses. Among them, we found that the intrinsic expression of IL1B (interleukin 1 beta), an essential proinflammatory gene, was directly regulated by ASH2L. These results revealed a novel role of ASH2L on the maintenance of breast cancer malignancy possibly through H3K4 methylation of the target inflammatory/immune responsive genes.

Detection of Increased Expression of Claudin-1 in Triple-Negative Breast Cancer: Analysis and Clinical-Pathological Correlation

Background Triple-negative breast cancer (TNBC) is a highly aggressive disease that lacks therapeutic targets and prognostic biomarkers. Claudin-1 is a well-described tight junction protein with prognostic value in many human cancers. Aims The need for the discovery of biomarkers of TNBC disease was a major reason for this study. Claudin-1 is a tight junction protein that has shown promising results in the prognosis and management of cancer in general. In the breast, claudin-1 expression and significance have shown variable results, especially in TNBC patients. Our study assessed expression of claudin-1 in a group of TNBC patients, and correlated this expression with clinical-pathological parameters, and with the expression of β-catenin. Materials and methods Tissues from a group of 52 TNBC patients were retrieved from the archives of the community hospital. All related information including demographical, pathologic and clinical data were retrieved. Immunohistochemistry assays of a rabbit polyclonal antibody anti-human claudin-1 were applied using the avidin-biotin peroxidase methodology. Results A statistically significant majority of TNBC cases positively expressed claudin-1 (81%, χ2=13.705; p<0.001). Most TNBC cases had grade 2 β-catenin expression (77.5%; p<0.001), and positive expression for claudin-1 correlated with that of β-catenin (χ2= 23.757; p<0.001). Claudin-1 and β-catenin expressions within tumour cells shared several features including absent or weakness of membranous expression, and redistribution of both proteins to the cytoplasm of tumour cells, and in some cases to the nuclei of these cells. Claudin-1 expression also correlates with adverse survival outcomes, where only four of 20 claudin-1-positive patients who received neo-adjuvant chemotherapy (NAC) achieved pathological complete response (pCR). Conclusions The above presents a complex role of claudin-1 in TNBC patients. In this study, claudin-1 expression was associated with poor prognostic features including invasion, metastases and adverse clinical outcomes. Claudin-1 expression in TNBC correlated with the expression of β-catenin, an important oncogene and a major contributor to the epithelial mesenchymal transition (EMT) phenomenon. Overall, the above results may serve as an impetus for further mechanistic studies to assess the exact role of claudin-1 in TNBC and its possible use in the management of this subset of breast cancer.

PROTACs in Epigenetic Cancer Therapy: Current Status and Future Opportunities

The epigenetic regulation of gene functions has been proven to be strongly associated with the development and progression of cancer. Reprogramming the cancer epigenome landscape is one of the most promising target therapies in both treatments and in reversing drug resistance. Proteolytic targeted chimeras (PROTACs) are an emerging therapeutic modality for selective degradation via the native ubiquitin-proteasome system. Rapid advances in PROTACs have facilitated the exploration of targeting epigenetic proteins, a lot of PROTAC degraders have already been designed in the field of epigenetic cancer therapy, and PROTACs targeting epigenetic proteins can better exploit target druggability and improve the mechanistic understanding of the epigenetic regulation of cancer. Thus, this review focuses on the progress made in the development of PROTAC degraders and PROTAC drugs targeting epigenetics in cancer and discusses challenges and future opportunities for the field.

Structure-based discovery of potent WD repeat domain 5 inhibitors that demonstrate efficacy and safety in preclinical animal models

WD repeat domain 5 (WDR5) is a core scaffolding component of many multiprotein complexes that perform a variety of critical chromatin-centric processes in the nucleus. WDR5 is a component of the mixed lineage leukemia MLL/SET complex and localizes MYC to chromatin at tumor-critical target genes. As a part of these complexes, WDR5 plays a role in sustaining oncogenesis in a variety of human cancers that are often associated with poor prognoses. Thus, WDR5 has been recognized as an attractive therapeutic target for treating both solid and hematological tumors. Previously, small-molecule inhibitors of the WDR5-interaction (WIN) site and WDR5 degraders have demonstrated robust in vitro cellular efficacy in cancer cell lines and established the therapeutic potential of WDR5. However, these agents have not demonstrated significant in vivo efficacy at pharmacologically relevant doses by oral administration in animal disease models. We have discovered WDR5 WIN-site inhibitors that feature bicyclic heteroaryl P7 units through structure-based design and address the limitations of our previous series of small-molecule inhibitors. Importantly, our lead compounds exhibit enhanced on-target potency, excellent oral pharmacokinetic (PK) profiles, and potent dose-dependent in vivo efficacy in a mouse MV4:11 subcutaneous xenograft model by oral dosing. Furthermore, these in vivo probes show excellent tolerability under a repeated high-dose regimen in rodents to demonstrate the safety of the WDR5 WIN-site inhibition mechanism. Collectively, our results provide strong support for WDR5 WIN-site inhibitors to be utilized as potential anticancer therapeutics.

RhoC in association with TET2/WDR5 regulates cancer stem cells by epigenetically modifying the expression of pluripotency genes

Emerging evidence illustrates that RhoC has divergent roles in cervical cancer progression where it controls epithelial to mesenchymal transition (EMT), migration, angiogenesis, invasion, tumor growth, and radiation response. Cancer stem cells (CSCs) are the primary cause of recurrence and metastasis and exhibit all of the above phenotypes. It, therefore, becomes imperative to understand if RhoC regulates CSCs in cervical cancer. In this study, cell lines and clinical specimen-based findings demonstrate that RhoC regulates tumor phenotypes such as clonogenicity and anoikis resistance. Accordingly, inhibition of RhoC abrogated these phenotypes. RNA-seq analysis revealed that RhoC over-expression resulted in up-regulation of 27% of the transcriptome. Further, the Infinium MethylationEPIC array showed that RhoC over-expressing cells had a demethylated genome. Studies divulged that RhoC via TET2 signaling regulated the demethylation of the genome. Further investigations comprising ChIP-seq, reporter assays, and mass spectrometry revealed that RhoC associates with WDR5 in the nucleus and regulates the expression of pluripotency genes such as Nanog. Interestingly, clinical specimen-based investigations revealed the existence of a subset of tumor cells marked by RhoC+/Nanog+ expression. Finally, combinatorial inhibition (in vitro) of RhoC and its partners (WDR5 and TET2) resulted in increased sensitization of clinical specimen-derived cells to radiation. These findings collectively reveal a novel role for nuclear RhoC in the epigenetic regulation of Nanog and identify RhoC as a regulator of CSCs. The study nominates RhoC and associated signaling pathways as therapeutic targets.

Histone modification and histone modification-targeted anti-cancer drugs in breast cancer: Fundamentals and beyond

Dysregulated epigenetic enzymes and resultant abnormal epigenetic modifications (EMs) have been suggested to be closely related to tumor occurrence and progression. Histone modifications (HMs) can assist in maintaining genome stability, DNA repair, transcription, and chromatin modulation within breast cancer (BC) cells. In addition, HMs are reversible, dynamic processes involving the associations of different enzymes with molecular compounds. Abnormal HMs (e.g. histone methylation and histone acetylation) have been identified to be tightly related to BC occurrence and development, even though their underlying mechanisms remain largely unclear. EMs are reversible, and as a result, epigenetic enzymes have aroused wide attention as anti-tumor therapeutic targets. At present, treatments to restore aberrant EMs within BC cells have entered preclinical or clinical trials. In addition, no existing studies have comprehensively analyzed aberrant HMs within BC cells; in addition, HM-targeting BC treatments remain to be further investigated. Histone and non-histone protein methylation is becoming an attractive anti-tumor epigenetic therapeutic target; such methylation-related enzyme inhibitors are under development at present. Consequently, the present work focuses on summarizing relevant studies on HMs related to BC and the possible mechanisms associated with abnormal HMs. Additionally, we also aim to analyze existing therapeutic agents together with those drugs approved and tested through pre-clinical and clinical trials, to assess their roles in HMs. Moreover, epi-drugs that target HMT inhibitors and HDAC inhibitors should be tested in preclinical and clinical studies for the treatment of BC. Epi-drugs that target histone methylation (HMT inhibitors) and histone acetylation (HDAC inhibitors) have now entered clinical trials or are approved by the US Food and Drug Administration (FDA). Therefore, the review covers the difficulties in applying HM-targeting treatments in clinics and proposes feasible approaches for overcoming such difficulties and promoting their use in treating BC cases.

Human WDR5 promotes breast cancer growth and metastasis via KMT2-independent translation regulation

Metastatic breast cancer remains a major cause of cancer-related deaths in women, and there are few effective therapies against this advanced disease. Emerging evidence suggests that key steps of tumor progression and metastasis are controlled by reversible epigenetic mechanisms. Using an in vivo genetic screen, we identified WDR5 as an actionable epigenetic regulator that is required for metastatic progression in models of triple-negative breast cancer. We found that knockdown of WDR5 in breast cancer cells independently impaired their tumorigenic as well as metastatic capabilities. Mechanistically, WDR5 promotes cell growth by increasing ribosomal gene expression and translation efficiency in a KMT2-independent manner. Consistently, pharmacological inhibition or degradation of WDR5 impedes cellular translation rate and the clonogenic ability of breast cancer cells. Furthermore, a combination of WDR5 targeting with mTOR inhibitors leads to potent suppression of translation and proliferation of breast cancer cells. These results reveal novel therapeutic strategies to treat metastatic breast cancer.

WIN site inhibition disrupts a subset of WDR5 function

WDR5 nucleates the assembly of histone-modifying complexes and acts outside this context in a range of chromatin-centric processes. WDR5 is also a prominent target for pharmacological inhibition in cancer. Small-molecule degraders of WDR5 have been described, but most drug discovery efforts center on blocking the WIN site of WDR5, an arginine binding cavity that engages MLL/SET enzymes that deposit histone H3 lysine 4 methylation (H3K4me). Therapeutic application of WIN site inhibitors is complicated by the disparate functions of WDR5, but is generally guided by two assumptions-that WIN site inhibitors disable all functions of WDR5, and that changes in H3K4me drive the transcriptional response of cancer cells to WIN site blockade. Here, we test these assumptions by comparing the impact of WIN site inhibition versus WDR5 degradation on H3K4me and transcriptional processes. We show that WIN site inhibition disables only a specific subset of WDR5 activity, and that H3K4me changes induced by WDR5 depletion do not explain accompanying transcriptional responses. These data recast WIN site inhibitors as selective loss-of-function agents, contradict H3K4me as a relevant mechanism of action for WDR5 inhibitors, and indicate distinct clinical applications of WIN site inhibitors and WDR5 degraders.

The roles of epigenetics in cancer progression and metastasis

Cancer metastasis remains a major clinical challenge for cancer treatment. It is therefore crucial to understand how cancer cells establish and maintain their metastatic traits. However, metastasis-specific genetic mutations have not been identified in most exome or genome sequencing studies. Emerging evidence suggests that key steps of metastasis are controlled by reversible epigenetic mechanisms, which can be targeted to prevent and treat the metastatic disease. A variety of epigenetic mechanisms were identified to regulate metastasis, including the well-studied DNA methylation and histone modifications. In the past few years, large scale chromatin structure alterations including reprogramming of the enhancers and chromatin accessibility to the transcription factors were shown to be potential driving force of cancer metastasis. To dissect the molecular mechanisms and functional output of these epigenetic changes, it is critical to use advanced techniques and alternative animal models for interdisciplinary and translational research on this topic. Here we summarize our current understanding of epigenetic aberrations in cancer progression and metastasis, and their implications in developing new effective metastasis-specific therapies.

The subtype-specific molecular function of SPDEF in breast cancer and insights into prognostic significance

Breast cancer (BC) is a molecular diverse disease which becomes the most common malignancy among women worldwide. There are four BC subtypes (Luminal A, Luminal B, HER2‐enriched and Basal‐like) robustly established following gene expression pattern‐based characterization, behave significant differences in terms of their incidence, risk factors, prognosis and therapeutic sensitivity. Thus, there is an urgent need to provide mechanism research, treatment strategies and/or prognosis evaluation based on the patient stratification of BC subtypes. The prostate‐derived ETS factor SPDEF was first identified as an activator of prostate specific antigen, and then, the involvements in many aspects of BC have been proposed. However, the subtype‐specific molecular function of SPDEF in BC and insights into prognostic significance have not been clearly elucidated. This study demonstrated for the first time that SPDEF may play a diversity role in the expression levels, clinicopathologic importance, biological function and prognostic evaluation in BC via bioinformatics and experimental evidence, which mainly depends on different BC subtyping. In summary, our findings would help to better understand the possible mechanisms of various BC subtypes and to find possible candidate genes for prognostic and therapeutic usage.

Structural insights into the recognition of histone H3Q5 serotonylation by WDR5

Serotonylation of histone H3Q5 (H3Q5ser) is a recently identified posttranslational modification of histones that acts as a permissive marker for gene activation in synergy with H3K4me3 during neuronal cell differentiation. However, any proteins that specifically recognize H3Q5ser remain unknown. Here, we found that WDR5 interacts with the N-terminal tail of histone H3 and functions as a "reader" for H3Q5ser. Crystal structures of WDR5 in complex with H3Q5ser and H3K4me3Q5ser peptides revealed that the serotonyl group is accommodated in a shallow surface pocket of WDR5. Experiments in neuroblastoma cells demonstrate that H3K4me3 modification is hampered upon disruption of WDR5-H3Q5ser interaction. WDR5 colocalizes with H3Q5ser in the promoter regions of cancer-promoting genes in neuroblastoma cells, where it promotes gene transcription to induce cell proliferation. Thus, beyond revealing a previously unknown mechanism through which WDR5 reads H3Q5ser to activate transcription, our study suggests that this WDR5-H3Q5ser-mediated epigenetic regulation apparently promotes tumorigenesis.

Cancer drug resistance induced by EMT: novel therapeutic strategies

Over the last decade, important clinical benefits have been achieved in cancer patients by using drug-targeting strategies. Nevertheless, drug resistance is still a major problem in most cancer therapies. Epithelial-mesenchymal plasticity (EMP) and tumour microenvironment have been described as limiting factors for effective treatment in many cancer types. Moreover, epithelial-to-mesenchymal transition (EMT) has also been associated with therapy resistance in many different preclinical models, although limited evidence has been obtained from clinical studies and clinical samples. In this review, we particularly deepen into the mechanisms of which intermediate epithelial/mesenchymal (E/M) states and its interconnection to microenvironment influence therapy resistance. We also describe how the use of bioinformatics and pharmacogenomics will help to figure out the biological impact of the EMT on drug resistance and to develop novel pharmacological approaches in the future.

WDR5 facilitates EMT and metastasis of CCA by increasing HIF-1α accumulation in Myc-dependent and independent pathways

Cholangiocarcinoma (CCA) is a highly aggressive malignancy with extremely poor prognoses. The oncogenic role and prognostic value of c-Myc in CCA is not well elucidated. WD repeat domain 5 (WDR5) is a critical regulatory factor directly interacting with c-Myc to regulate c-Myc recruitment at chromosomal locations, but the interaction of WDR5 and c-Myc in CCA was uncovered. In our study, we detected WDR5 and c-Myc expression in all CCA types, including intrahepatic (iCCA), perihilar (pCCA), and distal (dCCA) CCA, and evaluated their prognostic significance. Consequently, we demonstrated that WDR5 was significantly correlated with poor prognosis of CCA and that WDR5 and c-Myc co-expression was a more sensitive prognostic factor. With in vitro and in vivo experiments and bioinformatics, we showed that WDR5 interacted with the Myc box IIIb (MBIIIb) motif of c-Myc and facilitated Myc-induced HIF1A transcription, thereby promoting the epithelial-mesenchymal transition (EMT), invasion, and metastasis of CCA. Moreover, WDR5 enhanced hypoxia-inducible factor 1 subunit α (HIF-1α) accumulation by binding with histone deacetylase 2 (HDAC2) and increasing histone 3 lysine 4 acetylation (H3K4ac) deacetylation of the prolyl hydroxylase domain protein 2 (PHD2) promoter, resulting in the attenuation of chromatin opening and PHD2 expression, and eventually leading to HIF-1α stabilization and accumulation. In conclusion, WDR5 facilitated EMT and metastasis of CCA by increasing HIF-1α accumulation in a Myc-dependent pathway to promote HIF-1α transcription and a Myc-independent pathway to stabilize HIF-1α.

Impact of WIN site inhibitor on the WDR5 interactome

The chromatin-associated protein WDR5 is a promising pharmacological target in cancer, with most drug discovery efforts directed against an arginine-binding cavity in WDR5 called the WIN site. Despite a clear expectation that WIN site inhibitors will alter the repertoire of WDR5 interaction partners, their impact on the WDR5 interactome remains unknown. Here, we use quantitative proteomics to delineate how the WDR5 interactome is changed by WIN site inhibition. We show that the WIN site inhibitor alters the interaction of WDR5 with dozens of proteins, including those linked to phosphatidylinositol 3-kinase (PI3K) signaling. As proof of concept, we demonstrate that the master kinase PDPK1 is a bona fide high-affinity WIN site binding protein that engages WDR5 to modulate transcription of genes expressed in the G2 phase of the cell cycle. This dataset expands our understanding of WDR5 and serves as a resource for deciphering the action of WIN site inhibitors.

Targeting methyltransferase PRMT5 retards the carcinogenesis and metastasis of HNSCC via epigenetically inhibiting Twist1 transcription

Protein arginine methyltransferase 5 (PRMT5) is an important type II arginine methyltransferase that can play roles in cancers in a highly tissue-specific manner, but its role in the carcinogenesis and metastasis of head and neck squamous cell carcinoma (HNSCC) remains unclear. Here, we detected PRMT5 expression in HNSCC tissues and performed series of in vivo and in vitro assays to investigate the function and mechanism of PRMT5 in HNSCC. We found that PRMT5 was overexpressed in dysplastic and cancer tissues, and associated with lymph node metastasis and worse patient survival. PRMT5 knockdown repressed the malignant phenotype of HNSCC cells in vitro and in vivo. PRMT5 specific inhibitor blocked the formation of precancerous lesion and HNSCC in 4NQO-induced tongue carcinogenesis model, prevented lymph node metastasis in tongue orthotopic xenograft model and inhibited cancer development in subcutaneous xenograft model and Patient-Derived tumor Xenograft (PDX) model. Mechanistically, PRMT5-catalyzed H3R2me2s promotes the enrichment of H3K4me3 in the Twist1 promoter region by recruiting WDR5, and subsequently activates the transcription of Twist1. The rescue experiments indicated that overexpressed Twist1 abrogated the inhibition of cell invasion induced by PRMT5 inhibitor. In summary, this study elucidates that PRMT5 inhibition could reduce H3K4me3-mediated Twist1 transcription and retard the carcinogenesis and metastasis of HNSCC.

ZNF281-miR-543 Feedback Loop Regulates Transforming Growth Factor-β-Induced Breast Cancer Metastasis

Breast cancer is the most common malignancy, and metastasis is the main cause of cancer-associated mortality in women worldwide. Transforming growth factor-β (TGF-β) signaling, an inducer of epithelial-to-mesenchymal transition (EMT), plays an important role in breast cancer metastasis. Abnormal expression of miR-543 is associated with tumorigenesis and progression of various human cancers; however, the knowledge about the role of miR-543 in breast cancer metastasis is still unknown. In this study, we demonstrated that miR-543 inhibits the EMT-like phenotype and TGF-β-induced breast cancer metastasis both in vitro and in vivo by targeting ZNF281. ZNF281 transactivates the EMT-related transcription factor ZEB1 and Snail. Furthermore, both ZEB1 and Snail can transcriptionally suppress miR-543 expression. Taken together, our data uncover the ZNF281-miR-543 feedback loop and provide a mechanism to extend the understanding of TGF-β network complexity.

FBXW4 Is Highly Expressed and Associated With Poor Survival in Acute Myeloid Leukemia

The F-box and WD repeat domain-containing (FBXW) proteins play an important role in ubiquitin proteasome by inducing protein degradation. Ten FBXW proteins have been identified in humans. The functions of FBXW proteins, like FBXW7, have been well-established in many human cancers. However, little is known about their transcriptional expression profiles and relationship with prognosis in acute myeloid leukemia (AML). Here we investigated the roles of FBXW proteins in AML by analyzing their mRNA expression profiles and association with clinical features using data from EMBL-EBI, the Cancer Cell Line Encyclopedia, Gene Expression Profiling Interactive Analysis, and cBioPortal databases. Our results showed that the mRNA level of FBXW proteins were highly detected by microarray in 14 AML cell lines, although there were no obvious differences. The expression of FBXW4 was significantly higher in AML patients compared with that in normal controls (P < 0.01). Patients whose age was ≥60 years old had a higher FBXW4 expression when compared with those who were <60 years old (P < 0.05). Cytogenetic favorable-risk group patients had a much lower FBXW4 expression than the intermediate- and poor-risk group patients (P < 0.0001). Moreover, patients with high FBXW4 expression exhibited significantly shorter event-free survival (EFS) and overall survival (OS) than those with low FBXW4 expression (median EFS: 5.3 vs. 10.0 months, P = 0.025; median OS: 8.1 vs. 19.0 months, P= 0.015). A multivariate analysis indicated that high FBXW4 expression was an independent risk factor for poor EFS in AML patients who received intensive chemotherapy followed by allo-SCT. In summary, our data suggested that FBXW4 is aberrantly expressed in AML and high FBXW4 expression might be a poor prognostic biomarker; future functional and mechanistic studies will further illuminate the roles of FBXW4 in AML.