DOT1L Is a Novel Cancer Stem Cell Target for Triple-Negative Breast Cancer

Discovery of the first-in-class DOT1L PROTAC degrader

DOT1L is the lysine methyltransferase responsible for histone H3 lysine 79 (H3K79) methylation and plays a crucial role in leukemia progression. Furthermore, DOT1L has biological functions that are independent of its methyltransferase activity. Therefore, targeting and degrading DOT1L with PROteolysis TArgeting Chimeras (PROTACs) could represent a promising therapeutic strategy. Here, we report the discovery of the first-in-class DOT1L PROTAC degrader, compound 13 (MS2133), which potently induces DOT1L degradation in a concentration- and time-dependent manner, without affecting DOT1L mRNA expression. The DOT1L degradation induced by 13 requires binding to the E3 ligase von Hippel-Lindau (VHL) and DOT1L and occurs through the ubiquitin-proteasome system. 13 is selective for DOT1L over other methyltransferases and effectively inhibits the growth of mixed lineage leukemia-rearranged (MLL-r) leukemia cells while having no toxicity on normal cells. Overall, 13 is a valuable chemical biology tool for further studying functions of DOT1L and a potential therapeutic for DOT1L-dependent cancers.

Research progress and application status of organoid in breast cancer subtypes

Breast cancer (BC) is a prevalent malignant tumor that poses a significant health risk to women. The complexity of basic BC research and clinical treatment is influenced by multiple factors, including age, fertility, hormone metabolism, molecular subtypes, and tumor grading and staging. Traditional in vitro models often fall short of meeting modern research demands, whereas organoids-an emerging 3D primary culture technology-offer a unique platform that better replicates the tumor microenvironment (TME). Coupled with advances in high-throughput sequencing technologies, organoids have become increasingly valuable in biological and chemical research. Currently, the most widely used organoid model in BC research is the patient-derived organoid (PDO) model, which is generated directly from original tumor tissues. This paper aims to summarize the current status of PDO models across various BC subtypes, highlighting recent advances in genetics, mechanisms of drug resistance, identification of new therapeutic targets, and approaches to personalized treatment. In conclusion, the development of clinical precision medicine urgently requires in vitro models capable of accurately simulating the unique molecular subtypes of patients. This review will examine the challenges and future prospects of organoid models in BC research, offering new insights into the fundamental mechanisms of BC and paving the way for more effective personalized therapies.

Decoding the Epigenome of Breast Cancer

Breast cancer (BC) is the most prevalent malignancy among women, characterized by extensive heterogeneity stemming from molecular and genetic alterations. This review explores the intricate epigenetic landscape of BC, highlighting the significant role of epigenetic modifications-particularly DNA methylation, histone modifications, and the influence of non-coding RNAs-in the initiation, progression, and prognosis of the disease. Epigenetic alterations drive crucial processes, including gene expression regulation, cell differentiation, and tumor microenvironment interactions, contributing to tumorigenesis and metastatic potential. Notably, aberrations in DNA methylation patterns, including global hypomethylation and hypermethylation of CpG islands, have been associated with distinct BC subtypes, with implications for early detection and risk assessment. Furthermore, histone modifications, such as acetylation and methylation, affect cancer cell plasticity and aggressiveness by profoundly influencing chromatin dynamics and gene transcription. Finally, non-coding RNAs contribute by modulating epigenetic machinery and gene expression. Despite advances in our knowledge, clinical application of epigenetic therapies in BC is still challenging, often yielding limited efficacy when used alone. However, combining epi-drugs with established treatments shows promise for enhancing therapeutic outcomes. This review underscores the importance of integrating epigenetic insights into personalized BC treatment strategies, emphasizing the potential of epigenetic biomarkers for improving diagnosis, prognosis, and therapeutic response in affected patients.

DOT1L Mediates Stem Cell Maintenance and Represents a Therapeutic Vulnerability in Cancer

Tumor-initiating cancer stem cells (CSC) pose a challenge in human malignancies as they are largely treatment resistant and can seed local recurrence and metastasis. Epigenetic mechanisms governing cell fate decisions in embryonic and adult stem cells are deregulated in CSCs. This review focuses on the methyltransferase disruptor of telomeric silencing protein 1-like (DOT1L), which methylates histone H3 lysine 79 and is a key epigenetic regulator governing embryonic organogenesis and adult tissue stem cell maintenance. DOT1L is overexpressed in many human malignancies, and dysregulated histone H3 lysine 79 methylation is pathogenic in acute myeloid leukemia and several solid tumors. DOT1L regulates core stem cell genes governing CSC self-renewal, tumorigenesis, and multidrug resistance. Recent work has situated DOT1L as an attractive stem cell target in cancer. These reports showed that DOT1L is overexpressed and its protein activated specifically in malignant stem cells compared with bulk tumor cells, making them vulnerable to DOT1L inhibition in vitro and in vivo. Although early DOT1L inhibitor clinical trials were limited by inadequate drug bioavailability, accumulating preclinical data indicate that DOT1L critically regulates CSC self-renewal and might be more effective when given with other anticancer therapies. The appropriate combinations of DOT1L inhibitors with other agents and the sequence and timing of drug delivery for maximum efficacy warrant further investigation.

FBF1 maintains stem cell-like properties in breast cancer via PI3K/AKT/SOX2 axis

BACKGROUND

Considerable evidence suggests that tumor initiation, malignancy, metastasis and recurrence occur due to emergence of cancer stem cells (CSCs). Fas binding factor 1 (FBF1) is a multifunctional protein that plays essential roles in the regulation of development and cell fate decisions. However, the function in maintaining stem cell-like properties of breast cancer remains elusive.

METHODS

Tissue microarray was used to evaluate FBF1 expression. Cancer stemness assays were performed in FBF1 silencing and overexpressing cells in vitro and in a xenograft model in vivo. RNA sequencing, immunofluorescence and immunoprecipitation assays were performed to explore the underlying mechanism. Clinical expression and significance of FBF1 and stemness-associated factors were explored by analyzing datasets.

RESULTS

We report that FBF1 was highly expressed in breast cancer and significantly correlated with clinical progression. Silencing FBF1 in MDA-MB-231 cells restrained CSCs properties, including side population, sphere formation and migration, whereas ectopic FBF1 expression increased the side population proportion, enhanced the sphere formation ability, and promoted the expression of core stemness genes, such as SOX2, OCT4, KLF4 and NANOG, as well as facilitated metastasis of T47D breast cancer cells. Furthermore, mice bearing FBF1-overexpressed T47D xenografts had higher tumorigenic frequency and stronger metastasis potential. In addition, exploration of the underlying mechanism indicated that FBF1 binds PI3K which then activates PI3K-AKT phosphorylation cascades. Then the activated p-AKT interacts with stemness marker SOX2, elevates SOX2 and OCT4 activity, and finally forms PI3K/AKT/SOX2 axis, which mediates stem cell-like identities. Moreover, PI3K inhibitors abolished FBF1-mediated signaling pathway and diminished breast cancer stemness in vitro and in vivo. In 24 human breast cancer samples, we found a good positive correlation between the expression of FBF1 and p-AKT, as well as between FBF1 and SOX2 as determined by IHC. Clinical data showed that FBF1 expression was positively correlated with the expression of POU5F1 (OCT4), AKT1 and was negatively correlated with PTEN, which is a negative regulator of PI3K/AKT signaling.

CONCLUSION

Collectively, we identified a potential CSCs regulator and suggested a novel mechanism by which FBF1 governs cancer cell stemness. This study thus introduces an effective target for the diagnosis and treatment of breast cancer.

Cellular Epigenetic Targets and Epidrugs in Breast Cancer Therapy: Mechanisms, Challenges, and Future Perspectives

Breast cancer is the most common malignancy affecting women, manifesting as a heterogeneous disease with diverse molecular characteristics and clinical presentations. Recent studies have elucidated the role of epigenetic modifications in the pathogenesis of breast cancer, including drug resistance and efflux characteristics, offering potential new diagnostic and prognostic markers, treatment efficacy predictors, and therapeutic agents. Key modifications include DNA cytosine methylation and the covalent modification of histone proteins. Unlike genetic mutations, reprogramming the epigenetic landscape of the cancer epigenome is a promising targeted therapy for the treatment and reversal of drug resistance. Epidrugs, which target DNA methylation and histone modifications, can provide novel options for the treatment of breast cancer by reversing the acquired resistance to treatment. Currently, the most promising approach involves combination therapies consisting of epidrugs with immune checkpoint inhibitors. This review examines the aberrant epigenetic regulation of breast cancer initiation and progression, focusing on modifications related to estrogen signaling, drug resistance, cancer progression, and the epithelial-mesenchymal transition (EMT). It examines existing epigenetic drugs for treating breast cancer, including agents that modify DNA, inhibitors of histone acetyltransferases, histone deacetylases, histone methyltransferases, and histone demethyltransferases. It also delves into ongoing studies on combining epidrugs with other therapies and addresses the upcoming obstacles in this field.

Bevacizumab increases cisplatin efficacy by inhibiting epithelial-mesenchymal transition via ALDH1 in cervical carcinoma

Cervical carcinoma has the highest incidence among gynaecological cancers in developing countries where the human papillomavirus (HPV) vaccine is not yet widely used. Cancer stem cells (CSCs) are the key factors affecting treatment efficacy and cancer prognosis. Aldehyde dehydrogenase 1 (ALDH1) is a marker of CSCs, and its expression is closely related to chemotherapy resistance in cervical carcinoma. Bevacizumab is the most widely used molecular targeted drug in the management of cervical carcinoma. We designed and performed a series of in vitro and in vivo experiments to investigate the inhibitory effects of these compounds on ALDH1 and the underlying mechanism involved. The results revealed that bevacizumab significantly inhibited epithelial-mesenchymal transition (EMT) in HeLa cervical cancer cells, as indicated by upregulation of E-cadherin and downregulation of N-cadherin and snail. Anoxic pressure was relieved, and tumour vascularization was inhibited in the tumour microenvironment. NOTCH1 plays a critical role in these processes. Through modulating these tumour biological characteristics via ALDH1, bevacizumab increases the sensitivity of cervical carcinoma to cisplatin, suggesting that bevacizumab in combination with standard chemotherapy may represent a new strategy for overcoming drug resistance. Abbreviation: HPV, human papillomavirus; CSCs, cancer stem cells; ALDH1, aldehyde dehydrogenase 1; EMT, epithelial-mesenchymal transition; OD, optical density; qRT-PCR, RNA analysis by quantitative real-time polymerase chain reaction; RIPA, radioimmunoprecipitation assay; SDS-PAGE, sodium dodecyl sulphate-polyacrylamide gel electrophoresis; PVDF, polyvinylidene difluoride; ECL, electrochemiluminescence; NC, negative control; HE, haematoxylin and eosin; IHC, immunohistochemistry; DAB, 3, 3'-diaminobenzidine; IF, immunofluorescence; DAPI, 4,6-diamidino-2-phenylindole; VEGFA, vascular endothelial growth factor A; ROS, oxygen species; DFS, disease-free survival; OS, overall survival; HIF, hypoxia-inducible factor; PDGFs, platelet-derived growth factors; FGFs, fibroblast growth factors; PlGF, placenta growth factor; RTKs, receptor tyrosine kinases.

Cancer epigenetic therapy: recent advances, challenges, and emerging opportunities

Epigenetic dysregulation is an important nexus in the development and maintenance of human cancers. This review provides an overview of how understanding epigenetic dysregulation in cancers has led to insights for novel cancer therapy development. Over the past two decades, significant strides have been made in drug discovery efforts targeting cancer epigenetic mechanisms, leading to successes in clinical development and approval of cancer epigenetic therapeutics. This article will discuss the current therapeutic rationale guiding the discovery and development of epigenetic therapeutics, key learnings from clinical experiences and new opportunities on the horizon.

Bisphenol S exposure promotes stemness of triple-negative breast cancer cells via regulating Gli1-mediated Sonic hedgehog pathway

Bisphenol S (BPS), one of the most common alternatives for bisphenol A (BPA), has been implied to increase the risk of breast cancer. Triple-negative breast cancer (TNBC) is a highly aggressive type of breast cancer with a poor prognosis. However, the association between BPS and TNBC remains unclear. Cancer stem cells (CSCs) have a crucial role in breast cancer initiation, metastasis, and recurrence. Here, we proposed that BPS, equivalent to the human internal exposure and the environmental concentrations, enhanced CSC-like properties by upregulating sphere formation, self-renewal, the percentage of CD44+/CD24- cells, and the expression of CSC markers. Moreover, BPS promoted the migration, invasion, and epithelial-mesenchymal transition (EMT) in TNBC cells. Mechanistically, BPS activated the Sonic Hedgehog (SHH) signaling pathway in TNBC cells. Molecular docking analysis further showed that BPS upregulated SHH signaling pathway via directly binding Gli1 protein. Furthermore, inhibitor of SHH pathway or Gli1 siRNA attenuated the promoting effects of BPS on stemness, invasion, and migration of TNBC cells. In summary, our data firstly provide evidence that environmentally relevant BPS concentration treatment significantly enhanced TNBC malignant phenotype by activating the Sonic Hedgehog/Gli1 signaling pathway, raising high concerns about the potential population biology hazards of BPS.

Epigenetic Modifiers: Exploring the Roles of Histone Methyltransferases and Demethylases in Cancer and Neurodegeneration

Histone methyltransferases (HMTs) and histone demethylases (HDMs) are critical enzymes that regulate chromatin dynamics and gene expression through the addition and removal of methyl groups on histone proteins. HMTs, such as PRC2 and SETD2, are involved in the trimethylation of histone H3 at lysine 27 and lysine 36, influencing gene silencing and activation. Dysregulation of these enzymes often leads to abnormal gene expression and contributes to tumorigenesis. In contrast, HDMs including KDM7A and KDM2A reverse these methylation marks, and their dysfunction can drive disease progression. In cancer, the aberrant activity of specific HMTs and HDMs can lead to the silencing of tumor suppressor genes or the activation of oncogenes, facilitating tumor progression and resistance to therapy. Conversely, in neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), disruptions in histone methylation dynamics are associated with neuronal loss, altered gene expression, and disease progression. We aimed to comprehend the odd activity of HMTs and HDMs and how they contribute to disease pathogenesis, highlighting their potential as therapeutic targets. By advancing our understanding of these epigenetic regulators, this review provides new insights into their roles in cancer and neurodegenerative diseases, offering a foundation for future research.

The PIK3CA gene and its pivotal role in tumor tropism of triple-negative breast cancer

The PIK3CA gene is a linchpin in the intricate molecular network governing triple-negative breast cancer (TNBC) tumor tropism, serving as a focal point for understanding this aggressive disease. Anchored within the PI3K/AKT/mTOR signaling axis, PIK3CA mutations exert substantial influence, driving cellular processes that highlight the unique biology of TNBC. This review meticulously highlights the association between PIK3CA mutations and distinct TNBC subtypes, elucidating the gene's multifaceted contributions to tumor tropism. Molecular dissection reveals how PIK3CA mutations dynamically modulate chemokine responses, growth factor signaling, and extracellular matrix interactions, orchestrating the complex migratory behaviour characteristic of TNBC cells. A detailed exploration of PIK3CA-targeted strategies in the therapeutic arena is presented, outlining the current landscape of clinical trials and precision medicine approaches. As the scientific narrative converges, this review underscores the critical role of PIK3CA in shaping the molecular intricacies of TNBC tumor tropism and illuminates pathways toward tailored interventions, promising a paradigm shift in the clinical management of TNBC.

DOT1L: orchestrating methylation-dependent radiotheRAPy responses via BRCA1

Breast Cancer Type 1 Susceptibility Protein (BRCA)-1 existing in several functionally distinct complexes, promotes DNA repair of DNA double-strand breaks (DSBs). A recent study by Tang and colleagues identifies the lysine methyltransferase Disruptor of Telomeric Silencing 1-Like (DOT1L) involved in modifying Receptor-Associated Protein 80 (RAP80) to promote BRCA1-A complex localization and repair functions at DNA breaks. This study illuminates a potential therapeutic target for cancer radiotherapy.

Nitric oxide facilitates the S-nitrosylation and deubiquitination of Notch1 protein to maintain cancer stem cells in human NSCLC

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality, with tumour heterogeneity, fueled by cancer stem cells (CSCs), intricately linked to treatment resistance. Therefore, it is imperative to advance therapeutic strategies targeting CSCs in NSCLC. In this study, we utilized RNA sequencing to investigate metabolic pathway alterations in NSCLC CSCs and identified a crucial role of nitric oxide (NO) metabolism in governing CSC stemness, primarily through modulation of the Notch1 protein. Mechanistically, NO-induced S-nitrosylation of Notch1 facilitated its interaction with the deubiquitylase UCHL1, leading to increased Notch1 protein stability and enhanced CSC stemness. By inhibiting NO synthesis and downregulating UCHL1 expression, we validated the impact of NO on the Notch signalling pathway and CSC stemness. Importantly, targeting NO effectively reduced CSC populations within patient-derived organoids (PDOs) during radiotherapy. This mechanism presents a promising therapeutic target to surmount radiotherapy resistance in NSCLC treatment.

Discovery of Novel Non-nucleoside DOT1LR231Q Inhibitors with Improved Pharmacokinetic Properties and Anti-lung Cancer Efficacy

Given the considerable potential of DOT1LR231Q inhibitors in lung cancer therapy and the problematic pharmacokinetics of nucleoside inhibitors, our group launched a development program of non-nucleoside DOT1LR231Q inhibitors to improve the pharmacokinetic properties. Herein, two series of non-nucleoside compounds bearing piperidine or 3-(aminomethyl)pyrrolidin-3-ol as "ribose mimics" were designed and evaluated through antiproliferation assay and western blot analysis. The optimal TB22 inhibited the proliferation of H460R231Q cells with an IC50 value of 2.85 μM, about 13-fold more potent than SGC0946. Notably, TB22 demonstrated significant in vivo efficacy (TGI = 60.57%) in H460R231Q cell-derived xenograft models and improved pharmacokinetic properties (t1/2 = 6.06 ± 2.94 h and CL = 55.18 ± 8.56 mL/kg/min). Moreover, a mechanism study validated that TB22 suppressed malignant phenotypes of lung cancer cells harboring R231Q mutation via the MAPK/ERK signaling pathway. This work provides a promising molecule for lung cancer therapy in favor of clinical patients.

Prospects for breast cancer immunotherapy using microRNAs and transposable elements as objects

One of the directions in treatment of chemoresistant breast cancer (BC) may include new methods of activating the immune response against tumor cells. Clinically used checkpoint inhibition using antibodies to PD-1 and PD-L1 works in some patients, but the lack of biomarkers means number of respondents is low. The possibility of combining this method with chemotherapy is limited by an increased risk of toxic liver damage, development of immune-related pneumonitis, and thyroid dysfunction. This article includes introduction into the clinic of new methods of immunotherapy for BC, among which epigenetic activation of retroelements, double-stranded transcripts of which stimulate the interferon response against the tumor, is promising. For this purpose, inhibitors of DNA methyltransferase*, histone deacetylase* and histone methyltransferase* are used (* subtitles in the main text). Their antitumor effect is also mediated by removal of repressive epigenetic marks from tumor suppressor genes. However, numerous studies have proven the role of retroelements in the carcinogenesis of various malignant neoplasms, including BC. Moreover, endogenous retroviruses HERV-K and LINE1 retrotransposons are planned to be used as diagnostic biomarkers for BC. Therefore, a rational approach to using viral mimicry in antitumor therapy of BC may be the simultaneous suppression of specific retrotransposons (drivers for carcinogenesis) using reverse transcriptase inhibitors and silencing of specific transposons involved in carcinogenesis using complementary microRNAs. To determine possible pathways of influence in this direction, 35 specific transposon-derived microRNAs* changes in BC were identified, which can become guides for targeted therapy of BC.

Discovery of first-in-class DOT1L inhibitors against the R231Q gain-of-function mutation in the catalytic domain with therapeutic potential of lung cancer

Recent research certified that DOT1L and its mutations represented by R231Q were potential targets for the treatment of lung cancer. Herein, a series of adenosine-containing derivatives were identified with DOT1LR231Q inhibition through antiproliferation assay and Western blot analysis in the H460R231Q cell. The most promising compound 37 significantly reduced DOT1LR231Q mediated H3K79 methylation and effectively inhibited the proliferation, self-renewal, migration, and invasion of lung cancer cell lines at low micromolar concentrations. The cell permeability and cellular target engagement of 37 were verified by both CETSA and DARTS assays. In the H460R231Q OE cell-derived xenograft (CDX) model, 37 displayed pronounced tumor growth inhibition after intraperitoneal administration at 20 mg/kg dose for 3 weeks (TGI = 54.38%), without obvious toxicities. A pharmacokinetic study revealed that 37 possessed tolerable properties (t 1/2 = 1.93 ± 0.91 h, F = 97.2%) after intraperitoneal administration in rats. Mechanism study confirmed that 37 suppressed malignant phenotypes of lung cancer carrying R231Q gain-of-function mutation via the MAPK/ERK signaling pathway. Moreover, analysis of the binding modes between molecules and DOT1LWT/R231Q proteins put forward the "Induced-fit" allosteric model in favor to the discovery of potent DOT1L candidates.

Exploring the interplay between triple-negative breast cancer stem cells and tumor microenvironment for effective therapeutic strategies

Triple-negative breast cancer (TNBC) is a highly aggressive and metastatic malignancy with poor treatment outcomes. The interaction between the tumor microenvironment (TME) and breast cancer stem cells (BCSCs) plays an important role in the development of TNBC. Owing to their ability of self-renewal and multidirectional differentiation, BCSCs maintain tumor growth, drive metastatic colonization, and facilitate the development of drug resistance. TME is the main factor regulating the phenotype and metastasis of BCSCs. Immune cells, cancer-related fibroblasts (CAFs), cytokines, mesenchymal cells, endothelial cells, and extracellular matrix within the TME form a complex communication network, exert highly selective pressure on the tumor, and provide a conducive environment for the formation of BCSC niches. Tumor growth and metastasis can be controlled by targeting the TME to eliminate BCSC niches or targeting BCSCs to modify the TME. These approaches may improve the treatment outcomes and possess great application potential in clinical settings. In this review, we summarized the relationship between BCSCs and the progression and drug resistance of TNBC, especially focusing on the interaction between BCSCs and TME. In addition, we discussed therapeutic strategies that target the TME to inhibit or eliminate BCSCs, providing valuable insights into the clinical treatment of TNBC.

Modulatory effects of cancer stem cell-derived extracellular vesicles on the tumor immune microenvironment

Cancer stem cells (CSCs), accounting for only a minor cell proportion (< 1%) within tumors, have profound implications in tumor initiation, metastasis, recurrence, and treatment resistance due to their inherent ability of self-renewal, multi-lineage differentiation, and tumor-initiating potential. In recent years, accumulating studies indicate that CSCs and tumor immune microenvironment act reciprocally in driving tumor progression and diminishing the efficacy of cancer therapies. Extracellular vesicles (EVs), pivotal mediators of intercellular communications, build indispensable biological connections between CSCs and immune cells. By transferring bioactive molecules, including proteins, nucleic acids, and lipids, EVs can exert mutual influence on both CSCs and immune cells. This interaction plays a significant role in reshaping the tumor immune microenvironment, creating conditions favorable for the sustenance and propagation of CSCs. Deciphering the intricate interplay between CSCs and immune cells would provide valuable insights into the mechanisms of CSCs being more susceptible to immune escape. This review will highlight the EV-mediated communications between CSCs and each immune cell lineage in the tumor microenvironment and explore potential therapeutic opportunities.

Epigenetic contributions to cancer: Exploring the role of glycation reactions

Advanced Glycation End-products (AGEs), with their prolonged half-life in the human body, are emerging as potent diagnostic indicators. Early intervention studies, focusing on AGE cross-link breakers, have shown encouraging results in heart failure patients, paving the way for disease progression monitoring and therapy effectiveness evaluation. AGEs are the byproducts of a non-enzymatic reaction where sugars interact with proteins, lipids, and nucleic acids. These compounds possess the power to alter numerous biological processes, ranging from disrupting molecular conformation and promoting cross-linking to modifying enzyme activity, reducing clearance, and impairing receptor recognition. The damage inflicted by AGEs through the stimulation of intracellular signaling pathways is associated with the onset of chronic diseases across various organ systems. This review consolidates the characteristics of AGEs and the challenges posed by their expression in diverse physiological and pathological states. Furthermore, it highlights the clinical relevance of AGEs and the latest research breakthroughs aimed at reducing AGE accumulation.

PARP1-DOT1L transcription axis drives acquired resistance to PARP inhibitor in ovarian cancer

BACKGROUND

Poly (ADP-ribose) polymerase inhibitor (PARPi) resistance poses a significant challenge in ovarian carcinoma (OC). While the role of DOT1L in cancer and chemoresistance is acknowledged, its specific role in PARPi resistance remains unclear. This study aims to elucidate the molecular mechanism of DOT1L in PARPi resistance in OC patients.

METHODS

This study analyzed the expression of DOT1L in PARPi-resistant cell lines compared to sensitive ones and correlated it with clinical outcomes in OC patients. Comprehensive in vitro and in vivo functional experiments were conducted using cellular and mouse models. Molecular investigations, including RNA sequencing, chromatin immunoprecipitation (ChIP) and Cleavage Under Targets and Tagmentation (CUT&Tag) assays, were employed to unravel the molecular mechanisms of DOT1L-mediated PARPi resistance.

RESULTS

Our investigation revealed a robust correlation between DOT1L expression and clinical PARPi resistance in non-BRCA mutated OC cells. Upregulated DOT1L expression in PARPi-resistant tissues was associated with diminished survival in OC patients. Mechanistically, we identified that PARP1 directly binds to the DOT1L gene promoter, promoting transcription independently of its enzyme activity. PARP1 trapping induced by PARPi treatment amplified this binding, enhancing DOT1L transcription and contributing to drug resistance. Sequencing analysis revealed that DOT1L plays a crucial role in the transcriptional regulation of PLCG2 and ABCB1 via H3K79me2. This established the PARP1-DOT1L-PLCG2/ABCB1 axis as a key contributor to PARPi resistance. Furthermore, we discovered that combining a DOT1L inhibitor with PARPi demonstrated a synergistic effect in both cell line-derived xenograft mouse models (CDXs) and patient-derived organoids (PDOs).

CONCLUSIONS

Our results demonstrate that DOT1L is an independent prognostic marker for OC patients. The PARP1-DOT1L/H3K79me2-PLCG2/ABCB1 axis is identified as a pivotal contributor to PARPi resistance. Targeted inhibition of DOT1L emerges as a promising therapeutic strategy for enhancing PARPi treatment outcomes in OC patients.

The emerging role of DOT1L in cell proliferation and differentiation: Friend or foe

Cell proliferation and differentiation are the basic physiological activities of cells. Mistakes in these processes may affect cell survival, or cause cell cycle dysregulation, such as tumorigenesis, birth defects and degenerative diseases. In recent years, it has been found that histone methyltransferase DOT1L is the only H3 lysine 79 methyltransferase, which plays an important role in the process of cell fate determination through monomethylation, dimethylation and trimethylation of H3K79. DOT1L has a pro-proliferative effect in leukemia cells; however, loss of heart-specific DOT1L leads to increased proliferation of cardiac tissue. Additionally, DOT1L has carcinogenic or tumor suppressive effects in different neoplasms. At present, some DOT1L inhibitors for the treatment of MLL-driven leukemia have achieved promising results in clinical trials, but completely blocking DOT1L will also bring some side effects. Thus, this uncertainty suggests that DOT1L has a unique function in cell physiology. In this review, we summarize the primary findings of DOT1L in regulating cell proliferation and differentiation. Correlations between DOT1L and cell fate specification might suggest DOT1L as a therapeutic target for diseases.

Cancer epigenetics: from laboratory studies and clinical trials to precision medicine

Epigenetic dysregulation is a common feature of a myriad of human diseases, particularly cancer. Defining the epigenetic defects associated with malignant tumors has become a focus of cancer research resulting in the gradual elucidation of cancer cell epigenetic regulation. In fact, most stages of tumor progression, including tumorigenesis, promotion, progression, and recurrence are accompanied by epigenetic alterations, some of which can be reversed by epigenetic drugs. The main objective of epigenetic therapy in the era of personalized precision medicine is to detect cancer biomarkers to improve risk assessment, diagnosis, and targeted treatment interventions. Rapid technological advancements streamlining the characterization of molecular epigenetic changes associated with cancers have propelled epigenetic drug research and development. This review summarizes the main mechanisms of epigenetic dysregulation and discusses past and present examples of epigenetic inhibitors in cancer diagnosis and treatment, with an emphasis on the development of epigenetic enzyme inhibitors or drugs. In the final part, the prospect of precise diagnosis and treatment is considered based on a better understanding of epigenetic abnormalities in cancer.

Small molecules targeting selected histone methyltransferases (HMTs) for cancer treatment: Current progress and novel strategies

Histone methyltransferases (HMTs) play a critical role in gene post-translational regulation and diverse physiological processes, and are implicated in a plethora of human diseases, especially cancer. Increasing evidences demonstrate that HMTs may serve as a potential therapeutic target for cancer treatment. Thus, the development of HMTs inhibitor have been pursued with steadily increasing interest over the past decade. However, the disadvantages such as insufficient clinical efficacy, moderate selectivity, and propensity for acquired resistance have hindered the development of conventional HMT inhibitors. New technologies and methods are imperative to enhance the anticancer activity of HMT inhibitors. In this review, we first review the structure and biological functions of the several essential HMTs, such as EZH2, G9a, PRMT5, and DOT1L. The internal relationship between these HMTs and cancer is also expounded. Next, we mainly focus on the latest progress in the development of HMT modulators encompassing dual-target inhibitors, targeted protein degraders and covalent inhibitors from perspectives such as rational design, pharmacodynamics, pharmacokinetics, and clinical status. Lastly, we also discuss the challenges and future directions for HMT-based drug discovery for cancer therapy.

Molecular targets, therapeutic agents and multitasking nanoparticles to deal with cancer stem cells: A narrative review

There is increasing evidence that malignant tumors are initiated and maintained by a sub-population of tumor cells that have similar biological properties to normal adult stem cells. This very small population of Cancer Stem Cells (CSC) comprises tumor initiating cells responsible for cancer recurrence, drug resistance and metastasis. Conventional treatments such as chemotherapy, radiotherapy and surgery, in addition to being potentially toxic and non-specific, may paradoxically increase the population, spread and survival of CSCs. Next-generation sequencing and omics technologies are increasing our understanding of the pathways and factors involved in the development of CSCs, and can help to discover new therapeutic targets against CSCs. In addition, recent advances in nanomedicine have provided hope for the development of optimal specific therapies to eradicate CSCs. Moreover, the use of artificial intelligence and nano-informatics can elucidate new drug targets, and help to design drugs and nanoparticles (NPs) to deal with CSCs. In this review, we first summarize the properties of CSCs and describe the signaling pathways and molecular characteristics responsible for the emergence and survival of CSCs. Also, the location of CSCs within the tumor and the effect of host factors on the creation and maintenance of CSCs are discussed. Newly discovered molecular targets involved in cancer stemness and some novel therapeutic compounds to combat CSCs are highlighted. The optimum properties of anti-CSC NPs, including blood circulation and stability, tumor accumulation and penetration, cellular internalization, drug release, endosomal escape, and aptamers designed for specific targeting of CSCs are covered. Finally, some recent smart NPs designed for therapeutic and theranostic purposes to overcome CSCs are discussed.

The evaluation of six genes combined value in glioma diagnosis and prognosis

PURPOSE

Glioma is the most common and fatal type of brain tumour. Owing to its aggressiveness and lethality, early diagnosis and prediction of patient survival are very important. This study aimed to identify key genes and biomarkers for glioma that can guide clinicians in making rapid diagnosis and prognostication.

METHODS

Data mining of The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA), Repository of Molecular Brain Neoplasia Data, and Genotype-Tissue Expression Project brain expression data revealed significantly differentially expressed genes (DEGs), and the risk scores of individual patients were calculated. WGCNA was utilized to screen for genes most related to clinical diagnosis. Prognostic genes associated with glioma were selected via combining the LASSO regression with univariate and multivariate Cox regression and protein-protein interaction network analyses. Then, a nomogram was constructed. And CGGA dataset was utilized to validated. The protein expression levels of the signature were detected using the human protein atlas. Drug response prediction was carried out using the package "pRRophetic".

RESULTS

A six-gene signature (KLF6, CHI3L1, SERPINE1, ANGPT2, TGFBR1, and PTX3) was identified and used to stratify patients into low- and high-risk groups. Survival, ROC curve, and Cox analyses clarified that the six hub genes were a favourable independent prognostic factor for patients with glioma. A nomogram was set up by integrating clinical parameters with risk signatures, showing high precision for predicting 2-, 3-, 4-, 5-years survival. In addition, the expression of most genes was consistent with protein expression. Furthermore, the sensitivity to the top ten drugs in the GDSC database of the high-risk group was significantly higher than the low-risk group.

CONCLUSION

Based on genetic profiles and clinicopathological features, including age, grade, isocitrate dehydrogenase mutation status, we constructed a comprehensive prognostic model for patients with glioma. These signatures can be regarded as biomarkers to predict the prognosis of gliomas, possibly providing more therapeutic strategies for future clinical research.

Epigenetic control of cell signalling in cancer stem cells

The self-renewing cancer stem cells (CSCs) represent one of the distinct cell populations occurring in a tumour that can differentiate into multiple lineages. This group of sparsely abundant cells play a vital role in tumour survival and resistance to different treatments during cancer. The lack of exclusive markers associated with CSCs makes diagnosis and prognosis in cancer patients extremely difficult. This calls for the identification of unique regulators and markers for CSCs. Various signalling pathways like the Wnt/β-catenin pathway, Hedgehog pathway, Notch pathway, and TGFβ/BMP play a major role in the regulation and maintenance of CSCs. Epigenetic regulatory mechanisms add another layer of complexity to control these signalling pathways. In this chapter, we discuss about the role of epigenetic mechanisms in regulating the cellular signalling pathways in CSCs. The epigenetic regulatory mechanisms such as DNA methylation, histone modification and microRNAs can modulate the diverse effectors of signalling pathways and consequently the growth, differentiation and tumorigenicity of CSCs. In the end, we briefly discuss the therapeutic potential of targeting these epigenetic regulators and their target genes in CSCs.

Induction of Aryl Hydrocarbon Receptor-Mediated Cancer Cell-Selective Apoptosis in Triple-Negative Breast Cancer Cells by a High-Affinity Benzimidazoisoquinoline

Triple-negative breast cancer (TNBC) remains a disease with a paucity of targeted treatment opportunities. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is involved in a wide range of physiological processes, including the sensing of xenobiotics, immune function, development, and differentiation. Different small-molecule AhR ligands drive strikingly varied cellular and organismal responses. In certain cancers, AhR activation by select small molecules induces cell cycle arrest or apoptosis via activation of tumor-suppressive transcriptional programs. AhR is expressed in triple-negative breast cancers, presenting a tractable therapeutic opportunity. Here, we identify a novel ligand of the aryl hydrocarbon receptor that potently and selectively induces cell death in triple-negative breast cancer cells and TNBC stem cells via the AhR. Importantly, we found that this compound, Analog 523, exhibits minimal cytotoxicity against multiple normal human primary cells. Analog 523 represents a high-affinity AhR ligand with potential for future clinical translation as an anticancer agent.

Histone modifications in drug-resistant cancers: From a cancer stem cell and immune evasion perspective

The development and immune evasion of cancer stem cells (CSCs) limit the efficacy of currently available anticancer therapies. Recent studies have shown that epigenetic reprogramming regulates the expression of characteristic marker proteins and tumor plasticity associated with cancer cell survival and metastasis in CSCs. CSCs also possess unique mechanisms to evade external attacks by immune cells. Hence, the development of new strategies to restore dysregulated histone modifications to overcome cancer resistance to chemotherapy and immunotherapy has recently attracted attention. Restoring abnormal histone modifications can be an effective anticancer strategy to increase the therapeutic effect of conventional chemotherapeutic and immunotherapeutic drugs by weakening CSCs or by rendering them in a naïve state with increased sensitivity to immune responses. In this review, we summarize recent findings regarding the role of histone modifiers in the development of drug-resistant cancer cells from the perspectives of CSCs and immune evasion. In addition, we discuss attempts to combine currently available histone modification inhibitors with conventional chemotherapy or immunotherapy.

Combination of epidrugs with immune checkpoint inhibitors in cancer immunotherapy: From theory to therapy

Immunotherapy based on immune checkpoint inhibitors (ICIs) has revolutionized treatment strategies in multiple types of cancer. However, the resistance and relapse as associated with the extreme complexity of cancer-immunity interactions remain a major challenge to be resolved. Owing to the epigenome plasticity of cancer and immune cells, a growing body of evidence has been presented indicating that epigenetic treatments have the potential to overcome current limitations of immunotherapy, thus providing a rationalefor the combination of ICIs with epigenetic agents (epidrugs). In this review, we first make an overview about the epigenetic regulations in tumor biology and immunodevelopment. Subsequently, a diverse array of inhibitory agents under investigations targeted epigenetic modulators (Azacitidine, Decitabine, Vorinostat, Romidepsin, Belinostat, Panobinostat, Tazemetostat, Enasidenib and Ivosidenib, etc.) and immune checkpoints (Atezolizmab, Avelumab, Cemiplimab, Durvalumb, Ipilimumab, Nivolumab and Pembrolizmab, etc.) to increase anticancer responses were described and the potential mechanisms were further discussed. Finally, we summarize the findings of clinical trials and provide a perspective for future clinical studies directed at investigating the combination of epidrugs with ICIs as a treatment for cancer.

The Role of Histone Modification in DNA Replication-Coupled Nucleosome Assembly and Cancer

Histone modification regulates replication-coupled nucleosome assembly, DNA damage repair, and gene transcription. Changes or mutations in factors involved in nucleosome assembly are closely related to the development and pathogenesis of cancer and other human diseases and are essential for maintaining genomic stability and epigenetic information transmission. In this review, we discuss the role of different types of histone posttranslational modifications in DNA replication-coupled nucleosome assembly and disease. In recent years, histone modification has been found to affect the deposition of newly synthesized histones and the repair of DNA damage, further affecting the assembly process of DNA replication-coupled nucleosomes. We summarize the role of histone modification in the nucleosome assembly process. At the same time, we review the mechanism of histone modification in cancer development and briefly describe the application of histone modification small molecule inhibitors in cancer therapy.

The Role of Patient-Derived Organoids in Triple-Negative Breast Cancer Drug Screening

Triple-negative breast cancer (TNBC) is one of the most aggressive breast cancer subtypes, with a grave prognosis and few effective treatment options. Organoids represent revolutionary three-dimensional cell culture models, derived from stem or differentiated cells and preserving the capacity to differentiate into the cell types of their tissue of origin. The current review aims at studying the potential of patient-derived TNBC organoids for drug sensitivity testing as well as highlighting the advantages of the organoid technology in terms of drug screening. In order to identify relevant studies, a literature review was conducted using the MEDLINE and LIVIVO databases. The search terms “organoid” and “triple-negative breast cancer” were employed, and we were able to identify 25 studies published between 2018 and 2022. The current manuscript represents the first comprehensive review of the literature focusing on the use of patient-derived organoids for drug sensitivity testing in TNBC. Patient-derived organoids are excellent in vitro study models capable of promoting personalized TNBC therapy by reflecting the treatment responses of the corresponding patients and exhibiting high predictive value in the context of patient survival evaluation.

Dynamic tumor microenvironment, molecular heterogeneity, and distinct immunologic portrait of triple-negative breast cancer: an impact on classification and treatment approaches

Heterogeneity of the tumor microenvironment (TME) and the lack of a definite targetable receptor in triple-negative breast cancer (TNBC) has carved a niche for this cancer as a particularly therapeutically challenging form of breast cancer. However, recent advances in high-throughput genomic analysis have provided new insights into the unique microenvironment and defining characteristics of various subsets of TNBC. This improved understanding has contributed to the development of novel therapeutic strategies including targeted therapies such as PARP inhibitors and CDK inhibitors. Moreover, the recent FDA approval of the immune checkpoint inhibitor against programmed cell death protein 1 (PD-1), pembrolizumab and atezolizumab, holds the promise of improving the quality of life and increasing the overall survival of TNBC patients. This recent approval is one of the many therapeutically novel strategies that are currently being exploited in clinical trials toward eventual contribution to the oncologist's toolbox against TNBC. In this review, we comprehensively discuss TNBC's distinct TME and its immunophenotype. Furthermore, we highlight the histological and molecular classification of this cancer. More importantly, we describe how these characteristics and classifications contribute to the current standards of care and how they steer the development of newer and more targeted therapies toward achieving peak therapeutic goals in the treatment of TNBC.

DOT-1.1 (DOT1L) deficiency in C. elegans leads to small RNA-dependent gene activation

Methylation of histone H3 at lysine 79 (H3K79) is conserved from yeast to humans and is accomplished by Dot1 (disruptor of telomeric silencing-1) methyltransferases. The C. elegans enzyme DOT-1.1 and its interacting partners are similar to the mammalian DOT1L (Dot1-like) complex. The C. elegans DOT-1.1 complex has been functionally connected to RNA interference. Specifically, we have previously shown that embryonic and larval lethality of dot-1.1 mutant worms deficient in H3K79 methylation was suppressed by mutations in the RNAi pathway genes responsible for generation (rde-4) and function (rde-1) of primary small interfering RNAs (siRNAs). This suggests that dot-1.1 mutant lethality is dependent on the enhanced production of some siRNAs. We have also found that this lethality is suppressed by a loss-of-function of CED-3, a conserved apoptotic protease. Here, we describe a comparison of gene expression and primary siRNA production changes between control and dot-1.1 deletion mutant embryos. We found that elevated antisense siRNA production occurred more often at upregulated than downregulated genes. Importantly, gene expression changes were dependent on RDE-4 in both instances. Moreover, the upregulated group, which is potentially activated by ectopic siRNAs, was enriched in protease-coding genes. Our findings are consistent with a model where in the absence of H3K79 methylation there is a small RNA-dependent activation of protease genes, which leads to embryonic and larval lethality. DOT1 enzymes' conservation suggests that the interplay between H3K79 methylation and small RNA pathways may exist in higher organisms.

DOT1 L Regulates Ovarian Cancer Stem Cells by Activating β-catenin Signaling

Cancer stem cells (CSC) represent a population of cancer cells responsible for tumor initiation, chemoresistance, and metastasis. Here, we identified the H3K79 methyltransferase disruptor of telomeric silencing-1-like (DOT1L) as a critical regulator of self-renewal and tumor initiation in ovarian CSCs. DOT1 L was upregulated in ovarian CSCs versus non-CSCs. shRNA-mediated DOT1 L knockdown decreased the aldehyde dehydrogenase (ALDH)+ cell population, impaired the tumor initiation capacity (TIC) of ovarian CSCs, and blocked the expression of stemness-associated genes. Inhibition of DOT1L's methyltransferase activity by the small-molecule inhibitor (DOT1Li) EPZ-5676 also effectively targeted ovarian CSCs. Integrated RNA-sequencing analyses of ovarian cancer cells in which DOT1 L was knocked down versus control cells and of ovarian CSCs versus non-CSCs, identified Wnt signaling as a shared pathway deregulated in both CSCs and in DOT1L-deficient ovarian cancer cells. β-catenin, a key transcription factor regulated by Wnt, was downregulated in ovarian cancer cells in which DOT1 L was knocked down and upregulated in DOT1 L overexpressing ovarian cancer cells. Chromatin immunoprecipitation (ChIP) revealed enrichment of the H3K79Me3 mark at the β-catenin promoter, suggesting that its transcription is regulated by DOT1L. Our results suggest that DOT1 L is critical for the self-renewal and TIC of ovarian CSCs by regulating β-catenin signaling. Targeting DOT1 L in ovarian cancer could be a new strategy to eliminate CSCs.

IMPLICATIONS

This study found that the histone methyltransferase DOT1 L regulates the self-renewal and tumor initiation capacity of ovarian CSCs and suggests DOT1 L as a new cancer target.

Novel insights into histone lysine methyltransferases in cancer therapy: From epigenetic regulation to selective drugs

The reversible and precise temporal and spatial regulation of histone lysine methyltransferases (KMTs) is essential for epigenome homeostasis. The dysregulation of KMTs is associated with tumor initiation, metastasis, chemoresistance, invasiveness, and the immune microenvironment. Therapeutically, their promising effects are being evaluated in diversified preclinical and clinical trials, demonstrating encouraging outcomes in multiple malignancies. In this review, we have updated recent understandings of KMTs' functions and the development of their targeted inhibitors. First, we provide an updated overview of the regulatory roles of several KMT activities in oncogenesis, tumor suppression, and immune regulation. In addition, we summarize the current targeting strategies in different cancer types and multiple ongoing clinical trials of combination therapies with KMT inhibitors. In summary, we endeavor to depict the regulation of KMT-mediated epigenetic landscape and provide potential epigenetic targets in the treatment of cancers.

Targeting inflammatory macrophages rebuilds therapeutic efficacy of DOT1L inhibition in hepatocellular carcinoma

Epigenetic reprogramming is a promising therapeutic strategy for aggressive cancers, but its limitations in vivo remain unclear. Here, we showed, in detailed studies of data regarding 410 patients with human hepatocellular carcinoma (HCC), that increased histone methyltransferase DOT1L triggered epithelial-mesenchymal transition-mediated metastasis and served as a therapeutic target for human HCC. Unexpectedly, although targeting DOT1L in vitro abrogated the invasive potential of hepatoma cells, abrogation of DOT1L signals hardly affected the metastasis of hepatoma in vivo. Macrophages, which constitute the major cellular component of the stroma, abrogated the anti-metastatic effect of DOT1L targeting. Mechanistically, NF-κB signal elicited by macrophage inflammatory response operated via a non-epigenetic machinery to eliminate the therapeutic efficacy of DOT1L targeting. Importantly, therapeutic strategy combining DOT1L-targeted therapy with macrophage depletion or NF-κB inhibition in vivo effectively and successfully elicited cancer regression. Moreover, we found that the densities of macrophages in HCC determined malignant cell DOT1L-associated clinical outcome of the patients. Our results provide insight into the crosstalk between epigenetic reprogramming and cancer microenvironments and suggest that strategies to influence the functional activities of inflammatory cells may benefit epigenetic reprogramming therapy.

Targeting the super elongation complex for oncogenic transcription driven tumor malignancies: Progress in structure, mechanisms and small molecular inhibitor discovery

Oncogenic transcription activation is associated with tumor development and resistance derived from chemotherapy or target therapy. The super elongation complex (SEC) is an important complex regulating gene transcription and expression in metazoans closely related to physiological activities. In normal transcriptional regulation, SEC can trigger promoter escape, limit proteolytic degradation of transcription elongation factors and increase the synthesis of RNA polymerase II (POL II), and regulate many normal human genes to stimulate RNA elongation. Dysregulation of SEC accompanied by multiple transcription factors in cancer promotes rapid transcription of oncogenes and induce cancer development. In this review, we summarized recent progress in understanding the mechanisms of SEC in regulating normal transcription, and importantly its roles in cancer development. We also highlighted the discovery of SEC complex target related inhibitors and their potential applications in cancer treatment.

Chemical biology and pharmacology of histone lysine methylation inhibitors

Histone lysine methylation is a post-translational modification that plays a key role in the epigenetic regulation of a broad spectrum of biological processes. Moreover, the dysregulation of histone lysine methyltransferases (KMTs) has been implicated in the pathogenesis of several diseases particularly cancer. Due to their pathobiological importance, KMTs have garnered immense attention over the last decade as attractive therapeutic targets. These endeavors have culminated in tens of chemical probes that have been used to interrogate many aspects of histone lysine methylation. Besides, over a dozen inhibitors have been advanced to clinical trials, including the EZH2 inhibitor tazemetostat approved for the treatment of follicular lymphoma and advanced epithelioid sarcoma. In this Review, we highlight the chemical biology and pharmacology of KMT inhibitors and targeted protein degraders focusing on the clinical development of EZH1/2, DOT1L, Menin-MLL, and WDR5-MLL inhibitors. We also briefly discuss the pharmacologic targeting of other KMTs.

Histone methyltransferase Dot1L inhibits pancreatic cancer cell apoptosis by promoting NUPR1 expression

Objective

To explore functions of the histone H3 lysine 79 (K79) methyltransferase Dot1L in the development of pancreatic cancer and evaluate the possibility of targeting Dot1L to inhibit pancreatic cancer progression.

Methods

Patient samples were used to detect differences in Dot1L expression between tumor and adjacent tissues and to determine correlations between Dot1L expression in patients with different stages of pancreatic cancer. Lentiviral-mediated knockdown of Dot1L expression and flow cytometry were used to detect apoptosis in pancreatic cancer lacking Dot1L expression; chromatin immunoprecipitation and quantitative PCR were used to detect downstream target genes of Dot1L.

Results

We show that Dot1L is highly expressed in pancreatic cancer, and that its expression is related to pancreatic cancer stage. Knocking down Dot1L significantly promoted apoptosis in pancreatic cancer cells, while overexpressing Dot1L inhibited apoptosis. Mechanistically, Dot1L regulated apoptosis in pancreatic cancer cells by promoting NUPR1 expression. The enriched H3K79 trimethylation in the transcription initiation region of NUPR1 promoted its expression. Overexpressing NUPR1 inhibited the pancreatic cancer cell apoptosis caused by Dot1L knockdown.

Conclusions

Dot1L inhibits pancreatic cancer cell apoptosis by targeting NUPR1; thus, Dot1L is a promising target for pancreatic cancer treatment.