Epigenetic Therapy Ties MYC Depletion to Reversing Immune Evasion and Treating Lung Cancer

Bifunctional HDAC and DNMT inhibitor induces viral mimicry activates the innate immune response in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a unique breast cancer subtype characterized by a lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. Since TNBC lacks ER, PR, and HER2, there are currently no drugs that specifically target TNBC. Therefore, the development of new drugs or effective treatment strategies to target TNBC has become an urgent clinical need. Research has shown that the application of histone deacetylase (HDAC) inhibitors and DNA methyltransferase (DNMT) inhibitors leads to genomic and epigenomic instability. This, in turn, triggers the activation of pattern recognition receptors (PRRs) and subsequently activates downstream interferon (IFN) signalling pathways. In this study, the bifunctional HDAC and DNMT inhibitor J208 exhibited antitumour activity in TNBC cell lines. J208 effectively induced apoptosis and cell cycle arrest at the G0/G1 phase, inhibiting cell migration and invasion in TNBC. Moreover, this bifunctional inhibitor induced the expression of endogenous retroviruses (ERVs) and elicited a viral mimicry response, which increased the intracellular levels of double-stranded RNA (dsRNA) to activate the innate immune signalling pathway in TNBC. In summary, we demonstrated that the bifunctional inhibitor J208, which is designed to inhibit HDAC and DNMT, has potent anticancer effects, providing a new research basis for reactivating antitumour immunity by triggering innate immune signalling and offering a promising strategy for TNBC treatment.

Triune Nanomodulator Enables Exhausted Cytotoxic T Lymphocyte Rejuvenation for Cancer Epigenetic Immunotherapy

Oncogene activation and epigenome dysregulation drive tumor initiation and progression, contributing to tumor immune evasion and compromising the clinical response to immunotherapy. Epigenetic immunotherapy represents a promising paradigm in conquering cancer immunosuppression, whereas few relevant drug combination and delivery strategies emerge in the clinic. This study presents a well-designed triune nanomodulator, termed ROCA, which demonstrates robust capabilities in tumor epigenetic modulation and immune microenvironment reprogramming for cancer epigenetic immunotherapy. The nanomodulator is engineered from a nanoscale framework with epigenetic modulation and cascaded catalytic activity, which self-assembles into a nanoaggregate with tumor targeting polypeptide decoration that enables loading of the immunogenic cell death (ICD)-inducing agent. The nanomodulator releases active factors specifically triggered in the tumor microenvironment, represses oncogene expression, and initiates the type 1 T helper (TH1) cell chemokine axis by reversing DNA hypermethylation. This process, together with ICD induction, fundamentally reprograms the tumor microenvironment and significantly enhances the rejuvenation of exhausted cytotoxic T lymphocytes (CTLs, CD8+ T cells), which synergizes with the anti-PD-L1 immune checkpoint blockade and results in a boosted antitumor immune response. Furthermore, this strategy establishes long-term immune memory and effectively prevents orthotopic colon cancer relapse. Therefore, the nanomodulator holds promise as a standalone epigenetic immunotherapy agent or as part of a combination therapy with immune checkpoint inhibitors in preclinical cancer models, broadening the array of combinatorial strategies in cancer immunotherapy.

KiSS-1 Modulation by Epigenetic Agents Improves the Cisplatin Sensitivity of Lung Cancer Cells

Epigenetic alterations my play a role in the aggressive behavior of Non-Small Cell Lung Cancer (NSCLC). Treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA, vorinostat) has been reported to interfere with the proliferative and invasive potential of NSCLC cells. In addition, the DNA methyltransferase inhibitor azacytidine (AZA, vidaza) can modulate the levels of the metastasis suppressor KiSS-1. Thus, since cisplatin is still clinically available for NSCLC therapy, the aim of this study was to evaluate drug combinations between cisplatin and SAHA as well as AZA using cisplatin-sensitive H460 and -resistant H460/Pt NSCLC cells in relation to KiSS-1 modulation. An analysis of drug interaction according to the Combination-Index values indicated a more marked synergistic effect when the exposure to SAHA or AZA preceded cisplatin treatment with respect to a simultaneous schedule. A modulation of proteins involved in apoptosis (p53, Bax) was found in both sensitive and resistant cells, and compared to the treatment with epigenetic agents alone, the combination of cisplatin and SAHA or AZA increased apoptosis induction. The epigenetic treatments, both as single agents and in combination, increased the release of KiSS-1. Finally, the exposure of cisplatin-sensitive and -resistant cells to the kisspeptin KP10 enhanced cisplatin induced cell death. The efficacy of the combination of SAHA and cisplatin was tested in vivo after subcutaneous inoculum of parental and resistant cells in immunodeficient mice. A significant tumor volume inhibition was found when mice bearing advanced tumors were treated with the combination of SAHA and cisplatin according to the best schedule identified in cellular studies. These results, together with the available literature, support that epigenetic drugs are amenable for the combination treatment of NSCLC, including patients bearing cisplatin-resistant tumors.

When DNA damage responses meet tumor immunity: From mechanism to therapeutic opportunity

DNA damage is a prevalent phenomenon in the context of cancer progression. Evidence suggests that DNA damage responses (DDR) are pivotal in overcoming tumor immune evasion. Alternatively, traditional radiotherapy and chemotherapy operate by inducing DNA damage, consequently stimulating the immune system to target tumors. The intricate interplay between signaling pathways involved in DDR and immune activation underscores the significance of considering both factors in developing improved immunotherapies. By delving deeper into the mechanisms underlying immune activation brought on by DNA damage, it becomes possible to identify novel treatment approaches that boost the anticancer immune response while minimizing undesirable side effects. This review explores the mechanisms behind DNA damage-induced antitumor immune responses, the importance of DNA damage in antitumor immunity, and potential therapeutic approaches for cancer immunotherapy targeting DDR. Additionally, we discuss the challenges of combination therapy and strategies for integrating DNA damage-targeting therapies with current cancer immunotherapy. In summary, this review highlights the critical role of DNA damage in tumor immunology, underscoring the potential of DDR inhibitors as promising therapeutic modalities for cancer treatment.

Subtype-selective prenylated isoflavonoids disrupt regulatory drivers of MYCN-amplified cancers

Transcription factors have proven difficult to target with small molecules because they lack pockets necessary for potent binding. Disruption of protein expression can suppress targets and enable therapeutic intervention. To this end, we developed a drug discovery workflow that incorporates cell-line-selective screening and high-throughput expression profiling followed by regulatory network analysis to identify compounds that suppress regulatory drivers of disease. Applying this approach to neuroblastoma (NBL), we screened bioactive molecules in cell lines representing its MYC-dependent (MYCNA) and mesenchymal (MES) subtypes to identify selective compounds, followed by PLATESeq profiling of treated cells. This revealed compounds that disrupt a sub-network of MYCNA-specific regulatory proteins, resulting in MYCN degradation in vivo. The top hit was isopomiferin, a prenylated isoflavonoid that inhibited casein kinase 2 (CK2) in cells. Isopomiferin and its structural analogs inhibited MYC and MYCN in NBL and lung cancer cells, highlighting the general MYC-inhibiting potential of this unique scaffold.

Comparative analysis of microbial composition and functional characteristics in dental plaque and saliva of oral cancer patients

BACKGROUND

The oral cavity is home to various ecological niches, each with its own unique microbial composition. Understanding the microbial communities and gene composition in different ecological niches within the oral cavity of oral cancer (OC) patients is crucial for determining how these microbial populations contribute to disease progression.

METHODS

In this study, saliva and dental plaque samples were collected from patients with OC. Metagenomic sequencing was employed to analyze the microbial community classification and functional composition of the different sample groups.

RESULTS

The results of the study revealed significant differences in both the function and classification of microbial communities between saliva and dental plaque samples. The diversity of microbial species in saliva was found to be higher compared to  that in plaque samples. Notably, Actinobacteria were enriched in the dental plaque of OC patients. Furthermore, the study identified several inter-group differential marker species, including Prevotella intermedia, Haemophilus parahaemolyticus, Actinomyces radius, Corynebacterium matruchitii, and Veillonella atypica. Additionally, 1,353 differential genes were annotated into 23 functional pathways. Interestingly, a significant correlation was observed between differentially labeled species and Herpes simplex virus 1 (HSV-1) infection, which may be related to the occurrence and development of cancer.

CONCLUSIONS

Significant differences in the microbial and genetic composition of saliva and dental plaque samples were observed in OC patients. Furthermore, pathogenic bacteria associated with oral diseases were predominantly enriched in saliva. The identification of inter-group differential biomarkers and pathways provide insights into the relationship between oral microbiota and the occurrence and development of OC.

PARP inhibitor plus radiotherapy reshape the immune suppressive microenvironment and potentiate the efficacy of immune checkpoint inhibitors in tumors with IDH1 mutation

Isocitrate dehydrogenase 1 mutant (IDH1mut) tumors respond poorly to immunotherapy, but are more sensitive to chemoradiotherapy and poly (ADP-ribose) polymerase inhibition (PARPi). Accordingly, some efforts have aimed to capitalize on the IDH1 mutation rather than reverse it. Moreover, radiotherapy (RT) and PARPi can stimulate antitumor immunity, raising the possibility of reversing the immunosuppression caused by IDH1 mutation while killing the tumor. To assess this possibility, we treated IDH1mut tumors and cells with RT + PARPi. RT + PARPi showed enhanced efficacy over either modality alone both in vitro and in vivo. RT + PARPi induced more DNA damage and activated the cGAS-STING pathway more. IFNβ, CXCL10, and CCL5 were also more highly expressed at both the mRNA and protein levels. In two different tumor models, RT + PARPi increased infiltration and cytolytic function of CD8+ T cells, with one model also showing increased CD8+T cell proliferation. RT+PARPi also increased PD-L1 expression and enhanced checkpoint inhibition. Knocking out cGAS reversed the increased CD8+ T cell infiltration and the antitumor effect of RT+PARPi. We conclude that RT + PARPi reshapes the IDH1mut tumor immunosuppressive microenvironment, thereby augmenting checkpoint inhibition.

MYC Oncogene: A Druggable Target for Treating Cancers with Natural Products

Various diseases, including cancers, age-associated disorders, and acute liver failure, have been linked to the oncogene, MYC. Animal testing and clinical trials have shown that sustained tumor volume reduction can be achieved when MYC is inactivated, and different combinations of therapeutic agents including MYC inhibitors are currently being developed. In this review, we first provide a summary of the multiple biological functions of the MYC oncoprotein in cancer treatment, highlighting that the equilibrium points of the MYC/MAX, MIZ1/MYC/MAX, and MAD (MNT)/MAX complexes have further potential in cancer treatment that could be used to restrain MYC oncogene expression and its functions in tumorigenesis. We also discuss the multifunctional capacity of MYC in various cellular cancer processes, including its influences on immune response, metabolism, cell cycle, apoptosis, autophagy, pyroptosis, metastasis, angiogenesis, multidrug resistance, and intestinal flora. Moreover, we summarize the MYC therapy patent landscape and emphasize the potential of MYC as a druggable target, using herbal medicine modulators. Finally, we describe pending challenges and future perspectives in biomedical research, involving the development of therapeutic approaches to modulate MYC or its targeted genes. Patients with cancers driven by MYC signaling may benefit from therapies targeting these pathways, which could delay cancerous growth and recover antitumor immune responses.

Select EZH2 inhibitors enhance viral mimicry effects of DNMT inhibition through a mechanism involving NFAT:AP-1 signaling

DNA methyltransferase inhibitor (DNMTi) efficacy in solid tumors is limited. Colon cancer cells exposed to DNMTi accumulate lysine-27 trimethylation on histone H3 (H3K27me3). We propose this Enhancer of Zeste Homolog 2 (EZH2)-dependent repressive modification limits DNMTi efficacy. Here, we show that low-dose DNMTi treatment sensitizes colon cancer cells to select EZH2 inhibitors (EZH2is). Integrative epigenomic analysis reveals that DNMTi-induced H3K27me3 accumulates at genomic regions poised with EZH2. Notably, combined EZH2i and DNMTi alters the epigenomic landscape to transcriptionally up-regulate the calcium-induced nuclear factor of activated T cells (NFAT):activating protein 1 (AP-1) signaling pathway. Blocking this pathway limits transcriptional activating effects of these drugs, including transposable element and innate immune response gene expression involved in viral defense. Analysis of primary human colon cancer specimens reveals positive correlations between DNMTi-, innate immune response-, and calcium signaling-associated transcription profiles. Collectively, we show that compensatory EZH2 activity limits DNMTi efficacy in colon cancer and link NFAT:AP-1 signaling to epigenetic therapy-induced viral mimicry.

Dual inhibitors of DNMT and HDAC induce viral mimicry to induce antitumour immunity in breast cancer

The existing conventional treatments for breast cancer, including immune checkpoint blockade, exhibit limited effects in some cancers, particularly triple-negative breast cancer. Epigenetic alterations, specifically DNMT and HDAC alterations, are implicated in breast cancer pathogenesis. We demonstrated that DNMTs and HDACs are overexpressed and positively correlated in breast cancer. The combination of DNMT and HDAC inhibitors has shown synergistic antitumour effects, and our previously designed dual DNMT and HDAC inhibitor (termed DNMT/HDACi) 15a potently inhibits breast cancer cell proliferation, migration, and invasion and induces apoptosis in vitro and in vivo. Mechanistically, 15a induces a viral mimicry response by promoting the expression of endogenous retroviral elements in breast cancer cells, thus increasing the intracellular level of double-stranded RNA to activate the RIG-I-MAVS pathway. This in turn promotes the production of interferons and chemokines and augments the expression of interferon-stimulated genes and PD-L1. The combination of 15a and an anti-PD-L1 antibody had an additive effect in vivo. These findings indicate that this DNMT/HDACi has immunomodulatory functions and enhances the effectiveness of immune checkpoint blockade therapy. A novel dual DNMT and HDAC inhibitor induces viral mimicry, which induces the accumulation of dsRNA to activate tumoral IFN signalling and cytokine production to enhance the immune response in breast cancer.

Transcription of endogenous retroviruses in senescent cells contributes to the accumulation of double-stranded RNAs that trigger an anti-viral response that reinforces senescence

An important epigenetic switch marks the onset and maintenance of senescence. This allows transcription of the genetic programs that arrest the cell cycle and alter the microenvironment. Transcription of endogenous retroviruses (ERVs) is also a consequence of this epigenetic switch. In this manuscript, we have identified a group of ERVs that are epigenetically silenced in proliferating cells but are upregulated during replicative senescence or during various forms of oncogene-induced senescence, by RAS and Akt, or after HDAC4 depletion. In a HDAC4 model of senescence, removal of the repressive histone mark H3K27me3 is the plausible mechanism that allows the transcription of intergenic ERVs during senescence. We have shown that ERVs contribute to the accumulation of dsRNAs in senescence, which can initiate the antiviral response via the IFIH1-MAVS signaling pathway and thus contribute to the maintenance of senescence. This pathway, and MAVS in particular, plays an active role in shaping the microenvironment and maintaining growth arrest, two essential features of the senescence program.

Histone Deacetylase Inhibitors Directly Modulate T Cell Gene Expression and Signaling and Promote Development of Effector-Exhausted T Cells in Murine Tumors

Epigenetic regulation plays a crucial role in the development and progression of cancer, including the regulation of antitumor immunity. The reversible nature of epigenetic modifications offers potential therapeutic avenues for cancer treatment. In particular, histone deacetylase (HDAC) inhibitors (HDACis) have been shown to promote antitumor T cell immunity by regulating myeloid cell types, enhancing tumor Ag presentation, and increasing expression of chemokines. HDACis are currently being evaluated to determine whether they can increase the response rate of immune checkpoint inhibitors in cancer patients. Although the potential direct effect of HDACis on T cells likely impacts antitumor immunity, little is known about how HDAC inhibition alters the transcriptomic profile of T cells. In this article, we show that two clinical-stage HDACis profoundly impact gene expression and signaling networks in CD8+ and CD4+ T cells. Specifically, HDACis promoted T cell effector function by enhancing expression of TNF-α and IFN-γ and increasing CD8+ T cell cytotoxicity. Consistently, in a murine tumor model, HDACis led to enrichment of CD8+ T cell subsets with high expression of effector molecules (Prf1, Ifng, Gzmk, and Grmb) but also molecules associated with T cell exhaustion (Tox, Pdcd1, Lag3, and Havcr2). HDACis further generated a tumor microenvironment dominated by myeloid cells with immune suppressive signatures. These results indicate that HDACis directly and favorably augment T cell effector function but also increase their exhaustion signal in the tumor microenvironment, which may add a layer of complexity for achieving clinical benefit in combination with immune checkpoint inhibitors.

Targeting MYC at the intersection between cancer metabolism and oncoimmunology

MYC activation is a known hallmark of cancer as it governs the gene targets involved in various facets of cancer progression. Of interest, MYC governs oncometabolism through the interactions with its partners and cofactors, as well as cancer immunity via its gene targets. Recent investigations have taken interest in characterizing these interactions through multi-Omic approaches, to better understand the vastness of the MYC network. Of the several gene targets of MYC involved in either oncometabolism or oncoimmunology, few of them overlap in function. Prominent interactions have been observed with MYC and HIF-1α, in promoting glucose and glutamine metabolism and activation of antigen presentation on regulatory T cells, and its subsequent metabolic reprogramming. This review explores existing knowledge of the role of MYC in oncometabolism and oncoimmunology. It also unravels how MYC governs transcription and influences cellular metabolism to facilitate the induction of pro- or anti-tumoral immunity. Moreover, considering the significant roles MYC holds in cancer development, the present study discusses effective direct or indirect therapeutic strategies to combat MYC-driven cancer progression.

Preclinical pediatric brain tumor models for immunotherapy: Hurdles and a way forward

Brain tumors are the most common solid tumor in children and the leading cause of cancer-related deaths. Over the last few years, improvements have been made in the diagnosis and treatment of children with Central Nervous System tumors. Unfortunately, for many patients with high-grade tumors, the overall prognosis remains poor. Lower survival rates are partly attributed to the lack of efficacious therapies. The advent and success of immune checkpoint inhibitors (ICIs) in adults have sparked interest in investigating the utility of these therapies alone or in combination with other drug treatments in pediatric patients. However, to achieve improved clinical outcomes, the establishment and selection of relevant and robust preclinical pediatric high-grade brain tumor models is imperative. Here, we review the information that influenced our model selection as we embarked on an international collaborative study to test ICIs in combination with epigenetic modifying agents to enhance adaptive immunity to treat pediatric brain tumors. We also share challenges that we faced and potential solutions.

Nuclear to cytoplasmic transport is a druggable dependency in MYC-driven hepatocellular carcinoma

The MYC oncogene is often dysregulated in human cancer, including hepatocellular carcinoma (HCC). MYC is considered undruggable to date. Here, we comprehensively identify genes essential for survival of MYChigh but not MYClow cells by a CRISPR/Cas9 genome-wide screen in a MYC-conditional HCC model. Our screen uncovers novel MYC synthetic lethal (MYC-SL) interactions and identifies most MYC-SL genes described previously. In particular, the screen reveals nucleocytoplasmic transport to be a MYC-SL interaction. We show that the majority of MYC-SL nucleocytoplasmic transport genes are upregulated in MYChigh murine HCC and are associated with poor survival in HCC patients. Inhibiting Exportin-1 (XPO1) in vivo induces marked tumor regression in an autochthonous MYC-transgenic HCC model and inhibits tumor growth in HCC patient-derived xenografts. XPO1 expression is associated with poor prognosis only in HCC patients with high MYC activity. We infer that MYC may generally regulate and require altered expression of nucleocytoplasmic transport genes for tumorigenesis.

Towards targeting transposable elements for cancer therapy

Transposable elements (TEs) represent almost half of the human genome. Historically deemed 'junk DNA', recent technological advancements have stimulated a wave of research into the functional impact of TEs on gene-regulatory networks in evolution and development, as well as in diseases including cancer. The genetic and epigenetic evolution of cancer involves the exploitation of TEs, whereby TEs contribute directly to cancer-specific gene activities. This Review provides a perspective on the role of TEs in cancer as being a 'double-edged sword', both promoting cancer evolution and representing a vulnerability that could be exploited in cancer therapy. We discuss how TEs affect transcriptome regulation and other cellular processes in cancer. We highlight the potential of TEs as therapeutic targets for cancer. We also summarize technical hurdles in the characterization of TEs with genomic assays. Last, we outline open questions and exciting future research avenues.

HSF1 Inhibits Antitumor Immune Activity in Breast Cancer by Suppressing CCL5 to Block CD8+ T-cell Recruitment

Heat shock factor 1 (HSF1) is a stress-responsive transcription factor that promotes cancer cell malignancy. To provide a better understanding of the biological processes regulated by HSF1, here we developed an HSF1 activity signature (HAS) and found that it was negatively associated with antitumor immune cells in breast tumors. Knockdown of HSF1 decreased breast tumor size and caused an influx of several antitumor immune cells, most notably CD8+ T cells. Depletion of CD8+ T cells rescued the reduction in growth of HSF1-deficient tumors, suggesting HSF1 prevents CD8+ T-cell influx to avoid immune-mediated tumor killing. HSF1 suppressed expression of CCL5, a chemokine for CD8+ T cells, and upregulation of CCL5 upon HSF1 loss significantly contributed to the recruitment of CD8+ T cells. These findings indicate that HSF1 suppresses antitumor immune activity by reducing CCL5 to limit CD8+ T-cell homing to breast tumors and prevent immune-mediated destruction, which has implications for the lack of success of immune modulatory therapies in breast cancer.

SIGNIFICANCE

The stress-responsive transcription factor HSF1 reduces CD8+ T-cell infiltration in breast tumors to prevent immune-mediated killing, indicating that cellular stress responses affect tumor-immune interactions and that targeting HSF1 could improve immunotherapies.

Dual inhibitors of HDAC and other epigenetic regulators: A novel strategy for cancer treatment

A significant advancement in the field of epigenetic drug discovery has been evidenced in recent years. Epigenetic alterations are hereditary, nevertheless reversible variations to DNA or histone adaptations that regulate gene function individualistically of the fundamental sequence. The design and synthesis of various drugs targeting epigenetic regulators open a new door for epigenetic-targeted therapies to parade worthwhile therapeutic potential for haematological and solid malignancies. Several ongoing clinical trials on dual targeting strategy are being conducted comprising HDAC inhibitory component and an epigenetic regulating agent. In this perspective, the review discusses the pharmacological aspects of HDAC and other epigenetic regulating factors as dual inhibitors as an emerging alternative approach for combination therapies.

Novel dual inhibitors of PARP and HDAC induce intratumoral STING-mediated antitumor immunity in triple-negative breast cancer

PARP inhibitors and HDAC inhibitors have been approved for the clinical treatment of malignancies, but acquired resistance of or limited effects on solid tumors with a single agent remain as challenges. Bioinformatics analyses and a combination of experiments had demonstrated the synergistic effects of PARP and HDAC inhibitors in triple-negative breast cancer. A series of novel dual PARP and HDAC inhibitors were rationally designed and synthesized, and these molecules exhibited high enzyme inhibition activity with excellent antitumor effects in vitro and in vivo. Mechanistically, dual PARP and HDAC inhibitors induced BRCAness to restore synthetic lethality and promoted cytosolic DNA accumulation, which further activates the cGAS-STING pathway and produces proinflammatory chemokines through type I IFN-mediated JAK-STAT pathway. Moreover, these inhibitors promoted neoantigen generation, upregulated antigen presentation genes and PD-L1, and enhanced antitumor immunity when combined with immune checkpoint blockade therapy. These results indicated that novel dual PARP and HDAC inhibitors have antitumor immunomodulatory functions in triple-negative breast cancer. Novel dual PARP and HDAC inhibitors induce BRCAness to restore synthetic lethality, activating tumoral IFN signaling via the cGAS-STING pathway and inducing cytokine production, promoting neoantigen generation and presentation to enhance the immune response.

DNA methylation landscapes in DIPG reveal methylome variability that can be modified pharmacologically

Background

Diffuse intrinsic pontine glioma (DIPG) is a uniformly lethal brainstem tumor of childhood, driven by histone H3 K27M mutation and resultant epigenetic dysregulation. Epigenomic analyses of DIPG have shown global loss of repressive chromatin marks accompanied by DNA hypomethylation. However, studies providing a static view of the epigenome do not adequately capture the regulatory underpinnings of DIPG cellular heterogeneity and plasticity.

Methods

To address this, we performed whole-genome bisulfite sequencing on a large panel of primary DIPG specimens and applied a novel framework for analysis of DNA methylation variability, permitting the derivation of comprehensive genome-wide DNA methylation potential energy landscapes that capture intrinsic epigenetic variation.

Results

We show that DIPG has a markedly disordered epigenome with increasingly stochastic DNA methylation at genes regulating pluripotency and developmental identity, potentially enabling cells to sample diverse transcriptional programs and differentiation states. The DIPG epigenetic landscape was responsive to treatment with the hypomethylating agent decitabine, which produced genome-wide demethylation and reduced the stochasticity of DNA methylation at active enhancers and bivalent promoters. Decitabine treatment elicited changes in gene expression, including upregulation of immune signaling such as the interferon response, STING, and MHC class I expression, and sensitized cells to the effects of histone deacetylase inhibition.

Conclusions

This study provides a resource for understanding the epigenetic instability that underlies DIPG heterogeneity. It suggests the application of epigenetic therapies to constrain the range of epigenetic states available to DIPG cells, as well as the use of decitabine in priming for immune-based therapies.

Targeting the epigenome to reinvigorate T cells for cancer immunotherapy

Cancer immunotherapy using immune-checkpoint inhibitors (ICIs) has revolutionized the field of cancer treatment; however, ICI efficacy is constrained by progressive dysfunction of CD8+ tumor-infiltrating lymphocytes (TILs), which is termed T cell exhaustion. This process is driven by diverse extrinsic factors across heterogeneous tumor immune microenvironment (TIME). Simultaneously, tumorigenesis entails robust reshaping of the epigenetic landscape, potentially instigating T cell exhaustion. In this review, we summarize the epigenetic mechanisms governing tumor microenvironmental cues leading to T cell exhaustion, and discuss therapeutic potential of targeting epigenetic regulators for immunotherapies. Finally, we outline conceptual and technical advances in developing potential treatment paradigms involving immunostimulatory agents and epigenetic therapies.

Epigenome-Driven Strategies for Personalized Cancer Immunotherapy

Fighting cancer remains one of the greatest challenges for science in the 21st century. Advances in immunotherapy against different types of cancer have greatly contributed to the treatment, remission, and cure of patients. In this context, knowledge of epigenetic phenomena, their relationship with tumor cells and how the immune system can be epigenetically modulated represent some of the greatest advances in the development of anticancer therapies. Epigenetics is a rapidly growing field that studies how environmental factors can affect gene expression without altering DNA sequence. Epigenomic changes include DNA methylation, histone modifications, and non-coding RNA regulation, which impact cellular function. Epigenetics has shown promise in developing cancer therapies, such as immunotherapy, which aims to stimulate the immune system to attack cancer cells. For example, PD-1 and PD-L1 are biomarkers that regulate the immune response to cancer cells and recent studies have shown that epigenetic modifications can affect their expression, potentially influencing the efficacy of immunotherapy. New therapies targeting epigenetic modifications, such as histone deacetylases and DNA methyltransferases, are being developed for cancer treatment, and some have shown promise in preclinical studies and clinical trials. With growing understanding of epigenetic regulation, we can expect more personalized and effective cancer immunotherapies in the future. This review highlights key advances in the use of epigenetic and epigenomic tools and modern immuno-oncology strategies to treat several types of tumors.

Exploring Therapeutic Avenues in Lung Cancer: The Epigenetic Perspective

Lung cancer, primarily non-small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC), is distinguished by its high prevalence and marked mortality rates. Traditional therapeutic approaches, encompassing chemotherapy, radiation, and targeted therapies, frequently show limited efficacy due to acquired resistance and notable side effects. The objective of this review is to introduce a fresh perspective on the therapeutic strategies for lung cancer, emphasizing interventions targeting the epigenetic alterations often seen in this malignancy. This review presents the most recent advancements in the field, focusing on both past and current clinical trials related to the modulation of methylation patterns using diverse molecular agents. Furthermore, an in-depth analysis of the challenges and advantages of these methylation-modifying drugs will be provided, assessing their efficacy as individual treatments and their potential for synergy when integrated with prevailing therapeutic regimens.

Molecular Characteristics and Therapeutic Vulnerabilities of Claudin-low Breast Cancers Derived from Cell Line Models

BACKGROUND/AIM

Breast cancers constitute heterogeneous tumor groups and their categorization in subtypes based on the expression of the estrogen (ER), progesterone (PR) and HER2 receptors has advanced therapeutics. Claudin-low breast cancer has been proposed as an additional subtype which is mostly ER, PR and HER2 negative, but its identification has not led to corresponding specific treatments yet.

MATERIALS AND METHODS

Breast cancer cell lines from the Cancer Cell Line Encyclopedia (CCLE) were assessed for mRNA suppression of claudins and mRNA expression of ER and ERBB2 (the gene encoding HER2). The set of identified claudin-low cell lines were compared with representative ER-/ERBB2- cell lines for associated molecular alterations, gene dependencies through CRISPR and microRNA arrays and in vitro drug sensitivities using the Genomics of Drug Sensitivity in Cancer (GDSC) project.

RESULTS

Claudin-low cell lines display up-regulation of mRNA expression of epithelial to mesenchymal transition (EMT) regulators. Methylation sensitive genes are down-regulated in claudin-low lines compared with other cell lines, without associated up-regulation of DNA methyltransferases. Dependency screen microarrays reveal dependencies of claudin-low cell lines on components of the cytoskeleton but no consistent dependencies in known oncogenes or tumor suppressors. Potential drug sensitivities revealed in the drug screens included sensitivities to WNT pathway modulators, tyrosine kinase cascade inhibitors and BET inhibitors. On the other hand, claudin-low cell lines showed resistance to deacetylase inhibitors.

CONCLUSION

Claudin-low cell line models duplicate features of claudin-low breast cancers and may serve as guides for identification of drugs worth exploring for further development.

The increasing instance of negative emotion reduce the performance of emotion recognition

Introduction

Emotion recognition plays a crucial role in affective computing. Recent studies have demonstrated that the fuzzy boundaries among negative emotions make recognition difficult. However, to the best of our knowledge, no formal study has been conducted thus far to explore the effects of increased negative emotion categories on emotion recognition.

Methods

A dataset of three sessions containing consistent non-negative emotions and increased types of negative emotions was designed and built which consisted the electroencephalogram (EEG) and the electrocardiogram (ECG) recording of 45 participants.

Results

The results revealed that as negative emotion categories increased, the recognition rates decreased by more than 9%. Further analysis depicted that the discriminative features gradually reduced with an increase in the negative emotion types, particularly in the θ, α, and β frequency bands.

Discussion

This study provided new insight into the balance of emotion-inducing stimuli materials.

HDACi-dependent Microenvironmental Normalization Overcomes Tumor Burden-induced T-cell Exhaustion

PURPOSE

T-cell exhaustion limits immunotherapy for the treatment of solid tumors. Although immune checkpoint blockade and adoptive T-cell therapy (ACT) can mediate tumor regression, their potency is often determined by tumor burden. Here, we identified tumor burden-related pathway changes that are conducive to T-cell exhaustion. We then determined whether microenvironmental reprogramming via epigenetic modulation could reverse T-cell exhaustion and improve immunotherapeutic responsiveness.

EXPERIMENTAL DESIGN

We developed a murine syngeneic tumor model wherein an increased burden ablated therapeutic responsiveness to ACT, which corresponded with systemic induction of T-cell exhaustion. Transcriptome analysis of these large tumors allowed us to characterize changes to immunosuppressive pathway expression during class I histone deacetylase inhibitor MS-275 treatment. We then measured the therapeutic impact of MS-275 during ACT and assessed T-cell exhaustion by transcriptome/phenotypic analysis.

RESULTS

ACT durably regressed small tumors but failed to control large tumors, which were associated with systemic T-cell exhaustion and ablation of T-cell responses. Large tumors were defined by an immunosuppressive pathway signature. MS-275 reversed this pathway signature and promoted durable regression of large tumors during ACT. Prototypical exhaustion marker Tim-3 was selectively upregulated in transferred T cells despite displaying a reduced exhaustion signature. Instead, we observed enhanced activation-dependent signaling correlating with enrichment of the IL2-STAT5 signaling axis. Activated CD8+ T-cell responses were predominantly skewed toward terminal effector cell-like CD44+ Tim-3hi TCF1- CD127- KLRG1+ differentiation.

CONCLUSIONS

Tumor burden-induced pathway changes can be reversed through epigenetic reprogramming, enabling the conversion from T-cell exhaustion to effector lineage differentiation.

Unraveling MYC's Role in Orchestrating Tumor Intrinsic and Tumor Microenvironment Interactions Driving Tumorigenesis and Drug Resistance

The transcription factor MYC plays a pivotal role in regulating various cellular processes and has been implicated in tumorigenesis across multiple cancer types. MYC has emerged as a master regulator governing tumor intrinsic and tumor microenvironment interactions, supporting tumor progression and driving drug resistance. This review paper aims to provide an overview and discussion of the intricate mechanisms through which MYC influences tumorigenesis and therapeutic resistance in cancer. We delve into the signaling pathways and molecular networks orchestrated by MYC in the context of tumor intrinsic characteristics, such as proliferation, replication stress and DNA repair. Furthermore, we explore the impact of MYC on the tumor microenvironment, including immune evasion, angiogenesis and cancer-associated fibroblast remodeling. Understanding MYC's multifaceted role in driving drug resistance and tumor progression is crucial for developing targeted therapies and combination treatments that may effectively combat this devastating disease. Through an analysis of the current literature, this review's goal is to shed light on the complexities of MYC-driven oncogenesis and its potential as a promising therapeutic target.

Unleashing the efficacy of immune checkpoint inhibitors for advanced hepatocellular carcinoma: factors, strategies, and ongoing trials

Hepatocellular carcinoma (HCC) is a prevalent primary liver cancer, representing approximately 85% of cases. The diagnosis is often made in the middle and late stages, necessitating systemic treatment as the primary therapeutic option. Despite sorafenib being the established standard of care for advanced HCC in the past decade, the efficacy of systemic therapy remains unsatisfactory, highlighting the need for novel treatment modalities. Recent breakthroughs in immunotherapy have shown promise in HCC treatment, particularly with immune checkpoint inhibitors (ICIs). However, the response rate to ICIs is currently limited to approximately 15%-20% of HCC patients. Recently, ICIs demonstrated greater efficacy in "hot" tumors, highlighting the urgency to devise more effective approaches to transform "cold" tumors into "hot" tumors, thereby enhancing the therapeutic potential of ICIs. This review presented an updated summary of the factors influencing the effectiveness of immunotherapy in HCC treatment, identified potential combination therapies that may improve patient response rates to ICIs, and offered an overview of ongoing clinical trials focusing on ICI-based combination therapy.

Short-chain fatty acids in diseases

Short-chain fatty acids (SCFAs) are the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract. The absorption of SCFAs is mediated by substrate transporters, such as monocarboxylate transporter 1 and sodium-coupled monocarboxylate transporter 1, which promote cellular metabolism. An increasing number of studies have implicated metabolites produced by microorganisms as crucial executors of diet-based microbial influence on the host. SCFAs are important fuels for intestinal epithelial cells (IECs) and represent a major carbon flux from the diet, that is decomposed by the gut microbiota. SCFAs play a vital role in multiple molecular biological processes, such as promoting the secretion of glucagon-like peptide-1 by IECs to inhibit the elevation of blood glucose, increasing the expression of G protein-coupled receptors such as GPR41 and GPR43, and inhibiting histone deacetylases, which participate in the regulation of the proliferation, differentiation, and function of IECs. SCFAs affect intestinal motility, barrier function, and host metabolism. Furthermore, SCFAs play important regulatory roles in local, intermediate, and peripheral metabolisms. Acetate, propionate, and butyrate are the major SCFAs, they are involved in the regulation of immunity, apoptosis, inflammation, and lipid metabolism. Herein, we review the diverse functional roles of this major class of bacterial metabolites and reflect on their ability to affect intestine, metabolic, and other diseases. Video Abstract.

Exploring the regulatory role of lncRNA in cancer immunity

Imbalanced immune homeostasis in cancer microenvironment is a hallmark of cancer. Increasing evidence demonstrated that long non-coding RNAs (lncRNAs) have emerged as key regulatory molecules in directly blocking the cancer immunity cycle, apart from activating negative regulatory pathways for restraining tumor immunity. lncRNAs reshape the tumor microenvironment via the recruitment and activation of innate and adaptive lymphoid cells. In this review, we summarized the versatile mechanisms of lncRNAs implicated in cancer immunity cycle, including the inhibition of antitumor T cell activation, blockade of effector T cell recruitment, disruption of T cell homing, recruitment of immunosuppressive cells, and inducing an imbalance between antitumor effector cells (cytotoxic T lymphocytes, M1 macrophages, and T helper type 1 cells) versus immunosuppressive cells (M2 macrophages, T helper type 2 cells, myeloid derived suppressor cells, and regulatory T cells) that infiltrate in the tumor. As such, we would highlight the potential of lncRNAs as novel targets for immunotherapy.

The Transcriptional and Epigenetic Landscape of Cancer Cell Lineage Plasticity

Lineage plasticity, a process whereby cells change their phenotype to take on a different molecular and/or histologic identity, is a key driver of cancer progression and therapy resistance. Although underlying genetic changes within the tumor can enhance lineage plasticity, it is predominantly a dynamic process controlled by transcriptional and epigenetic dysregulation. This review explores the transcriptional and epigenetic regulators of lineage plasticity and their interplay with other features of malignancy, such as dysregulated metabolism, the tumor microenvironment, and immune evasion. We also discuss strategies for the detection and treatment of highly plastic tumors.

SIGNIFICANCE

Lineage plasticity is a hallmark of cancer and a critical facilitator of other oncogenic features such as metastasis, therapy resistance, dysregulated metabolism, and immune evasion. It is essential that the molecular mechanisms of lineage plasticity are elucidated to enable the development of strategies to effectively target this phenomenon. In this review, we describe key transcriptional and epigenetic regulators of cancer cell plasticity, in the process highlighting therapeutic approaches that may be harnessed for patient benefit.

A T Cell-Engaging Tumor Organoid Platform for Pancreatic Cancer Immunotherapy

Pancreatic ductal adenocarcinoma (PDA) is a clinically challenging disease with limited treatment options. Despite a small percentage of cases with defective mismatch DNA repair (dMMR), PDA is included in the most immune-resistant cancer types that are poorly responsive to immune checkpoint blockade (ICB) therapy. To facilitate drug discovery combating this immunosuppressive tumor type, a high-throughput drug screen platform is established with the newly developed T cell-incorporated pancreatic tumor organoid model. Tumor-specific T cells are included in the pancreatic tumor organoids by two-step cell packaging, fully recapitulating immune infiltration in the immunosuppressive tumor microenvironment (TME). The organoids are generated with key components in the original tumor, including epithelial, vascular endothelial, fibroblast and macrophage cells, and then packaged with T cells into their outside layer mimicking a physical barrier and enabling T cell infiltration and cytotoxicity studies. In the PDA organoid-based screen, epigenetic inhibitors ITF2357 and I-BET151 are identified, which in combination with anti-PD-1 based therapy show considerably greater anti-tumor effect. The combinatorial treatment turns the TME from immunosuppressive to immunoactive, up-regulates the MHC-I antigen processing and presentation, and enhances the effector T cell activity. The standardized PDA organoid model has shown great promise to accelerate drug discovery for the immunosuppressive cancer.

Heterogeneity of the tumor immune microenvironment and clinical interventions

The tumor immune microenvironment (TIME) is broadly composed of various immune cells, and its heterogeneity is characterized by both immune cells and stromal cells. During the course of tumor formation and progression and anti-tumor treatment, the composition of the TIME becomes heterogeneous. Such immunological heterogeneity is not only present between populations but also exists on temporal and spatial scales. Owing to the existence of TIME, clinical outcomes can differ when a similar treatment strategy is provided to patients. Therefore, a comprehensive assessment of TIME heterogeneity is essential for developing precise and effective therapies. Facilitated by advanced technologies, it is possible to understand the complexity and diversity of the TIME and its influence on therapy responses. In this review, we discuss the potential reasons for TIME heterogeneity and the current approaches used to explore it. We also summarize clinical intervention strategies based on associated mechanisms or targets to control immunological heterogeneity.

SMYD3 represses tumor-intrinsic interferon response in HPV-negative squamous cell carcinoma of the head and neck

Cancers often display immune escape, but the mechanisms are incompletely understood. Herein, we identify SMYD3 as a mediator of immune escape in human papilloma virus (HPV)-negative head and neck squamous cell carcinoma (HNSCC), an aggressive disease with poor response to immunotherapy with pembrolizumab. SMYD3 depletion induces upregulation of multiple type I interferon (IFN) response and antigen presentation machinery genes in HNSCC cells. Mechanistically, SMYD3 binds to and regulates the transcription of UHRF1, encoding for a reader of H3K9me3, which binds to H3K9me3-enriched promoters of key immune-related genes, recruits DNMT1, and silences their expression. SMYD3 further maintains the repression of immune-related genes through intragenic deposition of H4K20me3. In vivo, Smyd3 depletion induces influx of CD8+ T cells and increases sensitivity to anti-programmed death 1 (PD-1) therapy. SMYD3 overexpression is associated with decreased CD8 T cell infiltration and poor response to neoadjuvant pembrolizumab. These data support combining SMYD3 depletion strategies with checkpoint blockade to overcome anti-PD-1 resistance in HPV-negative HNSCC.

Derivation of CD8+ T cell infiltration potentiators in non-small-cell lung cancer through tumor microenvironment analysis

Non-small-cell lung cancer remains a deadly form of human cancer even in the era of immunotherapy with existing immunotherapy strategies currently only benefiting a minority of patients. Therefore, the derivation of treatment options, which might extend the promise of immunotherapy to more patients, remains of paramount importance. Here, we define using TCGA lung squamous and lung adenocarcinoma RNAseq datasets a significant correlation between epigenetic therapy actionable interferon genes with both predicted tumor immune score generally, and CD8A specifically. IHC validation using primary sample tissue microarrays confirmed a pronounced positive association between CD8⁺ T cell tumor infiltration and the interferon-associated targets, CCL5 and MDA5. We next extended these findings to the assessment of clinical trial biopsies from patients with advanced non-small-cell lung cancer treated with epigenetic therapy with and without concurrent immunotherapy. These analyses revealed treatment-associated increases in both CD8⁺ T cell intratumoral infiltration and microenvironment CCL5 staining intensity.

Redefining Precision Management of r/r Large B-Cell Lymphoma: Novel Antibodies Take on CART and BMT in the Quest for Future Treatment Strategies

The treatment paradigms for patients with relapsed large B-cell lymphoma are expanding. Chimeric antigen receptor technology (CAR-T) has revolutionized the management of these patients. Novel bispecific antibodies and antibody-drug conjugates, used as chemotherapy-free single agents or in combination with other novel therapeutics, have been quickly introduced into the real-world setting. With such a paradigm shift, patients have an improved chance of better outcomes with unpredictable complete remission rates. Additionally, the excellent tolerance of new antibodies targeting B-cell lymphomas is another motivation to broaden its use in relapsed and refractory patients. With the increasing number of approved therapy approaches, future research needs to focus on optimizing the sequence and developing new combination strategies for these antibodies, both among themselves and with other agents. Clinical, pathological, and genetic risk profiling can assist in identifying which patients are most likely to benefit from these costly therapeutic options. However, new combinations may lead to new side effects, which we must learn to deal with. This review provides a comprehensive overview of the current state of research on several innovative antibodies for the precision management of large B-cell lymphoma. It explores various treatment strategies, such as CAR-T vs. ASCT, naked antibodies, antibody-drug conjugates, bispecific antibodies, and bispecific T-cell engagers, as well as discussing the challenges and future perspectives of novel treatment strategies. We also delve into resistance mechanisms and factors that may affect decision making. Moreover, each section provides a detailed analysis of the available literature and ongoing clinical trials.

MYC regulates CSF1 expression via microRNA 17/20a to modulate tumor-associated macrophages in osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor of childhood. Approximately 20%-30% of OSs carry amplification of chromosome 8q24, which harbors the oncogene c-MYC and correlates with a poor prognosis. To understand the mechanisms that underlie the ability of MYC to alter both the tumor and its surrounding tumor microenvironment (TME), we generated and molecularly characterized an osteoblast-specific Cre-Lox-Stop-Lox-c-MycT58A p53fl/+ knockin genetically engineered mouse model (GEMM). Phenotypically, the Myc-knockin GEMM had rapid tumor development with a high incidence of metastasis. MYC-dependent gene signatures in our murine model demonstrated significant homology to the human hyperactivated MYC OS. We established that hyperactivation of MYC led to an immune-depleted TME in OS demonstrated by the reduced number of leukocytes, particularly macrophages. MYC hyperactivation led to the downregulation of macrophage colony-stimulating factor 1, through increased microRNA 17/20a expression, causing a reduction of macrophage population in the TME of OS. Furthermore, we developed cell lines from the GEMM tumors, including a degradation tag-MYC model system, which validated our MYC-dependent findings both in vitro and in vivo. Our studies utilized innovative and clinically relevant models to identify a potentially novel molecular mechanism through which MYC regulates the profile and function of the OS immune landscape.

MYC Induces Immunotherapy and IFNγ Resistance Through Downregulation of JAK2

Immunotherapy has revolutionized the treatment of advanced melanoma. Because the pathways mediating resistance to immunotherapy are largely unknown, we conducted transcriptome profiling of preimmunotherapy tumor biopsies from patients with melanoma that received PD-1 blockade or adoptive cell therapy with tumor-infiltrating lymphocytes. We identified two melanoma-intrinsic, mutually exclusive gene programs, which were controlled by IFNγ and MYC, and the association with immunotherapy outcome. MYC-overexpressing melanoma cells exhibited lower IFNγ responsiveness, which was linked with JAK2 downregulation. Luciferase activity assays, under the control of JAK2 promoter, demonstrated reduced activity in MYC-overexpressing cells, which was partly reversible upon mutagenesis of a MYC E-box binding site in the JAK2 promoter. Moreover, silencing of MYC or its cofactor MAX with siRNA increased JAK2 expression and IFNγ responsiveness of melanomas, while concomitantly enhancing the effector functions of T cells coincubated with MYC-overexpressing cells. Thus, we propose that MYC plays a pivotal role in immunotherapy resistance through downregulation of JAK2.

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.

Metabolic reprogramming and epigenetic modifications in cancer: from the impacts and mechanisms to the treatment potential

Metabolic reprogramming and epigenetic modifications are hallmarks of cancer cells. In cancer cells, metabolic pathway activity varies during tumorigenesis and cancer progression, indicating regulated metabolic plasticity. Metabolic changes are often closely related to epigenetic changes, such as alterations in the expression or activity of epigenetically modified enzymes, which may exert a direct or an indirect influence on cellular metabolism. Therefore, exploring the mechanisms underlying epigenetic modifications regulating the reprogramming of tumor cell metabolism is important for further understanding tumor pathogenesis. Here, we mainly focus on the latest studies on epigenetic modifications related to cancer cell metabolism regulations, including changes in glucose, lipid and amino acid metabolism in the cancer context, and then emphasize the mechanisms related to tumor cell epigenetic modifications. Specifically, we discuss the role played by DNA methylation, chromatin remodeling, noncoding RNAs and histone lactylation in tumor growth and progression. Finally, we summarize the prospects of potential cancer therapeutic strategies based on metabolic reprogramming and epigenetic changes in tumor cells.

New insights and options into the mechanisms and effects of combined targeted therapy and immunotherapy in prostate cancer

Chronic inflammation is believed to drive prostate carcinogenesis by producing reactive oxygen species or reactive nitrogen species to induce DNA damage. This effect might subsequently cause epigenetic and genomic alterations, leading to malignant transformation. Although established therapeutic advances have extended overall survival, tumors in patients with advanced prostate cancer are prone to metastasis, transformation into metastatic castration-resistant prostate cancer, and therapeutic resistance. The tumor microenvironment (TME) of prostate cancer is involved in carcinogenesis, invasion and drug resistance. A plethora of preclinical studies have focused on immune-based therapies. Understanding the intricate TME system in prostate cancer may hold much promise for developing novel therapies, designing combinational therapeutic strategies, and further overcoming resistance to established treatments to improve the lives of prostate cancer patients. In this review, we discuss nonimmune components and various immune cells within the TME and their putative roles during prostate cancer initiation, progression, and metastasis. We also outline the updated fundamental research focusing on therapeutic advances of targeted therapy as well as combinational options for prostate cancer.

Targeting tumor endothelial cells with methyltransferase inhibitors: Mechanisms of action and the potential of combination therapy

Tumor endothelial cells (TECs) reside in the inner lining of blood vessels and represent a promising target for targeted cancer therapy. DNA methylation is a chemical process that involves the transfer of a methyl group to a specific base in the DNA strand, catalyzed by DNA methyltransferase (DNMT). DNMT inhibitors (DNMTis) can inhibit the activity of DNMTs, thereby preventing the transfer of methyl groups from s-adenosyl methionine (SAM) to cytosine. Currently, the most viable therapy for TECs is the development of DNMTis to release cancer suppressor genes from their repressed state. In this review, we first outline the characteristics of TECs and describe the development of tumor blood vessels and TECs. Abnormal DNA methylation is closely linked to tumor initiation, progression, and cell carcinogenesis, as evidenced by numerous studies. Therefore, we summarize the role of DNA methylation and DNA methyltransferase and the therapeutic potential of four types of DNMTi in targeting TECs. Finally, we discuss the accomplishments, challenges, and opportunities associated with combination therapy with DNMTis for TECs.

Mechanisms of CD8+ T cell exclusion and dysfunction in cancer resistance to anti-PD-(L)1

CD8⁺ T cells are the front-line defensive cells against cancer. Reduced infiltration and effector function of CD8⁺ T cells occurs in cancer and is contributed to defective immunity and immunotherapy resistance. Exclusion and exhaustion of CD8⁺ T cells are the two key factors associated with reduced durability of immune checkpoint inhibitor (ICI) therapy. Initially activated T cells upon exposure to chronic antigen stimulation or immunosuppressive tumor microenvironment (TME) acquire a hyporesponsive state that progressively lose their effector function. Thus, a key strategy in cancer immunotherapy is to look for factors contributed to defective CD8⁺ T cell infiltration and function. Targeting such factors can define a promising supplementary approach in patients receiving anti-programmed death-1 receptor (PD-1)/anti-programmed death-ligand 1 (PD-L1) therapy. Recently, bispecific antibodies are developed against PD-(L)1 and a dominant factor within TME, representing higher safety profile and exerting more desired outcomes. The focus of this review is to discuss about promoters of deficient infiltration and effector function of CD8⁺ T cells and their addressing in cancer ICI therapy.

Intrinsic suppression of type I interferon production underlies the therapeutic efficacy of IL-15-producing natural killer cells in B-cell acute lymphoblastic leukemia

BACKGROUND

Type I interferons (IFN-Is), secreted by hematopoietic cells, drive immune surveillance of solid tumors. However, the mechanisms of suppression of IFN-I-driven immune responses in hematopoietic malignancies including B-cell acute lymphoblastic leukemia (B-ALL) are unknown.

METHODS

Using high-dimensional cytometry, we delineate the defects in IFN-I production and IFN-I-driven immune responses in high-grade primary human and mouse B-ALLs. We develop natural killer (NK) cells as therapies to counter the intrinsic suppression of IFN-I production in B-ALL.

RESULTS

We find that high expression of IFN-I signaling genes predicts favorable clinical outcome in patients with B-ALL, underscoring the importance of the IFN-I pathway in this malignancy. We show that human and mouse B-ALL microenvironments harbor an intrinsic defect in paracrine (plasmacytoid dendritic cell) and/or autocrine (B-cell) IFN-I production and IFN-I-driven immune responses. Reduced IFN-I production is sufficient for suppressing the immune system and promoting leukemia development in mice prone to MYC-driven B-ALL. Among anti-leukemia immune subsets, suppression of IFN-I production most markedly lowers the transcription of IL-15 and reduces NK-cell number and effector maturation in B-ALL microenvironments. Adoptive transfer of healthy NK cells significantly prolongs survival of overt ALL-bearing transgenic mice. Administration of IFN-Is to B-ALL-prone mice reduces leukemia progression and increases the frequencies of total NK and NK-cell effectors in circulation. Ex vivo treatment of malignant and non-malignant immune cells in primary mouse B-ALL microenvironments with IFN-Is fully restores proximal IFN-I signaling and partially restores IL-15 production. In B-ALL patients, the suppression of IL-15 is the most severe in difficult-to-treat subtypes with MYC overexpression. MYC overexpression promotes sensitivity of B-ALL to NK cell-mediated killing. To counter the suppressed IFN-I-induced IL-15 production in MYC^high human B-ALL, we CRISPRa-engineered a novel human NK-cell line that secretes IL-15. CRISPRa IL-15-secreting human NK cells kill high-grade human B-ALL in vitro and block leukemia progression in vivo more effectively than NK cells that do not produce IL-15.

CONCLUSION

We find that restoration of the intrinsically suppressed IFN-I production in B-ALL underlies the therapeutic efficacy of IL-15-producing NK cells and that such NK cells represent an attractive therapeutic solution for the problem of drugging MYC in high-grade B-ALL.

HDAC inhibitor HPTA initiates anti-tumor response by CXCL9/10-recruited CXCR3+CD4+T cells against PAHs carcinogenicity

Polycyclic aromatic hydrocarbons (PAHs) exposure in food is closely associated with the occurrence and development of breast cancer, which may attribute to altered immunotoxicity and immune regulation. Currently, cancer immunotherapy aims to promote tumor-specific T cell responses, especially CD4⁺T helper cells (Th) for anti-tumor immunity. The histone deacetylase inhibitors (HDACis) are found to exert an anti-tumor effect by reshaping the tumor immune microenvironment, but the immune regulatory mechanism of HDACis in PAHs-induced breast tumor remains elusive. Here, using established breast cancer models induced by 7,12-dimethylbenz[a]anthracene (DMBA), a potent carcinogenic agent of PAH, the novel HDACi, 2-hexyl-4-pentylene acid (HPTA) exhibited anti-tumor effect by activating T lymphocytes immune function. HPTA recruited CXCR3⁺CD4⁺T cells into chemokines CXCL9/10-enriched tumor sites, the increased secretion of CXCL9/10 was regulated by the NF-κB-mediated pathway. Furthermore, HPTA promoted Th1 differentiation and assisted cytotoxic CD8⁺T cells in the elimination of breast cancer cells. These findings support the proposition of HPTA as a potential therapeutic in the treatment of PAHs-induced carcinogenicity.

MYC activation impairs cell-intrinsic IFNγ signaling and confers resistance to anti-PD1/PD-L1 therapy in lung cancer

Elucidating the adaptive mechanisms that prevent host immune response in cancer will help predict efficacy of anti-programmed death-1 (PD1)/L1 therapies. Here, we study the cell-intrinsic response of lung cancer (LC) to interferon-γ (IFNγ), a cytokine that promotes immunoresponse and modulates programmed death-ligand 1 (PD-L1) levels. We report complete refractoriness to IFNγ in a subset of LCs as a result of JAK2 or IFNGR1 inactivation. A submaximal response affects another subset that shows constitutive low levels of IFNγ-stimulated genes (IγSGs) coupled with decreased H3K27ac (histone 3 acetylation at lysine 27) deposition and promoter hypermethylation and reduced IFN regulatory factor 1 (IRF1) recruitment to the DNA on IFNγ stimulation. Most of these are neuroendocrine small cell LCs (SCLCs) with oncogenic MYC/MYCL1/MYCN. The oncogenic activation of MYC in SCLC cells downregulates JAK2 and impairs IγSGs stimulation by IFNγ. MYC amplification tends to associate with a worse response to anti-PD1/L1 therapies. Hence alterations affecting the JAK/STAT pathway and MYC activation prevent stimulation by IFNγ and may predict anti-PD1/L1 efficacy in LC.

Intratumour Fusobacterium nucleatum and immune response to oesophageal cancer

BACKGROUND

Experimental evidence suggests a role of intratumour Fusobacterium nucleatum in the aggressive behaviour of gastrointestinal cancer through downregulating anti-tumour immunity. We investigated the relationship between intratumour F. nucleatum and immune response to oesophageal cancer.

METHODS

Utilising an unbiased database of 300 resected oesophageal cancers, we measured F. nucleatum DNA in tumour tissue using a quantitative polymerase chain reaction assay, and evaluated the relationship between the abundance of F. nucleatum and the densities of T cells (CD8 + , FOXP3 + and PDCD1 + ), as well as lymphocytic reaction patterns (follicle lymphocytic reaction, peritumoural lymphocytic reaction, stromal lymphocytic reaction and tumour-infiltrating lymphocytes) in oesophageal carcinoma tissue.

RESULTS

F. nucleatum was significantly and inversely associated only with the peritumoural lymphocytic reaction (P = 0.0002). Compared with the F. nucleatum-absent group, the F. nucleatum-high group showed a much lower level of the peritumoural lymphocytic reaction (univariable odds ratio, 0.33; 95% confidence interval, 0.16-0.65; P = 0.0004). A multivariable model yielded a similar finding (multivariable odds ratio, 0.34; 95% confidence interval 0.16-0.69; P = 0.002).

CONCLUSIONS

Intratumour F. nucleatum is associated with a diminished peritumoural lymphocytic reaction, providing a platform for further investigations on the potential interactive roles between intratumour F. nucleatum and host immunity.

Epigenetic state determines the in vivo efficacy of STING agonist therapy

While STING-activating agents have shown limited efficacy in early-phase clinical trials, multiple lines of evidence suggest the importance of tumor cell-intrinsic STING function in mediating antitumor immune responses. Although STING signaling is impaired in human melanoma, its restoration through epigenetic reprogramming can augment its antigenicity and T cell recognition. In this study, we show that reversal of methylation silencing of STING in murine melanoma cell lines using a clinically available DNA methylation inhibitor can improve agonist-induced STING activation and type-I IFN induction, which, in tumor-bearing mice, can induce tumor regression through a CD8⁺ T cell-dependent immune response. These findings not only provide mechanistic insight into how STING signaling dysfunction in tumor cells can contribute to impaired responses to STING agonist therapy, but also suggest that pharmacological restoration of STING signaling through epigenetic reprogramming might improve the therapeutic efficacy of STING agonists.

Guadecitabine increases response to combined anti-CTLA-4 and anti-PD-1 treatment in mouse melanoma in vivo by controlling T-cells, myeloid derived suppressor and NK cells

BACKGROUND

The combination of Programmed Cell Death 1 (PD-1) and Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) blockade has dramatically improved the overall survival rate for malignant melanoma. Immune checkpoint blockers (ICBs) limit the tumor's immune escape yet only for approximately a third of all tumors and, in most cases, for a limited amount of time. Several approaches to overcome resistance to ICBs are being investigated among which the addition of epigenetic drugs that are expected to act on both immune and tumor cells. Guadecitabine, a dinucleotide prodrug of a decitabine linked via phosphodiester bond to a guanosine, showed promising results in the phase-1 clinical trial, NIBIT-M4 (NCT02608437).

METHODS

We used the syngeneic B16F10 murine melanoma model to study the effects of immune checkpoint blocking antibodies against CTLA-4 and PD-1 in combination, with and without the addition of Guadecitabine. We comprehensively characterized the tumor's and the host's responses under different treatments by flow cytometry, multiplex immunofluorescence and methylation analysis.

RESULTS

In combination with ICBs, Guadecitabine significantly reduced subcutaneous tumor growth as well as metastases formation compared to ICBs and Guadecitabine treatment. In particular, Guadecitabine greatly enhanced the efficacy of combined ICBs by increasing effector memory CD8+ T cells, inducing effector NK cells in the spleen and reducing tumor infiltrating regulatory T cells and myeloid derived suppressor cells (MDSC), in the tumor microenvironment (TME). Guadecitabine in association with ICBs increased serum levels of IFN-γ and IFN-γ-induced chemokines with anti-angiogenic activity. Guadecitabine led to a general DNA-demethylation, in particular of sites of intermediate methylation levels.

CONCLUSIONS

These results indicate Guadecitabine as a promising epigenetic drug to be added to ICBs therapy.

HDAC3 is critical in tumor development and therapeutic resistance in Kras-mutant non-small cell lung cancer

HDAC3 is one of the main targets of histone deacetylase (HDAC) inhibitors in clinical development as cancer therapies, yet the in vivo role of HDAC3 in solid tumors is unknown. We identified a critical role for HDAC3 in Kras-mutant lung cancer. Using genetically engineered mouse models (GEMMs), we found that HDAC3 is required for lung tumor growth in vivo. HDAC3 was found to direct and enhance the transcription effects of the lung cancer lineage transcription factor NKX2-1 to mediate expression of a common set of target genes. We identified FGFR1 as a critical previously unidentified target of HDAC3. Leveraging this, we identified that an HDAC3-dependent transcriptional cassette becomes hyperactivated as Kras/LKB1-mutant cells develop resistance to the MEK inhibitor trametinib, and this can be reversed by treatment with the HDAC1/HDAC3 inhibitor entinostat. We found that the combination of entinostat plus trametinib treatment elicits therapeutic benefit in the Kras/LKB1 GEMM.