Inhibition of the HDAC/Suv39/G9a pathway restores the expression of DNA damage-dependent major histocompatibility complex class I-related chain A and B in cancer cells

Small molecule compounds targeting G9a/GLP: Recent advances and perspectives

As an important member of the histone methyltransferase family, G9a/GLP has been shown to be closely related to the occurrence and development of various diseases, such as tumors, fibrosis, and malaria. Selective small molecule inhibitors of G9a/GLP were first reported in 2007, and over the decade since then, more than 40 different types of G9a modulators have been developed. Classification by binding site includes s-adenosylmethionine (SAM)-competitive inhibitors and substrate-competitive inhibitors. According to the mechanism of action, these compounds can be divided into reversible inhibitors, irreversible inhibitors, dual inhibitors, degraders, etc. In this paper, we systematically reviewed the discovery methods, design strategies, structural optimization processes, binding modes, biological activity data, and pharmacokinetic properties of small molecules targeting G9a/GLP. This paper analyzed the challenges and opportunities in the development of small molecule compounds targeting G9a/GLP, aiming to offer valuable insights and perspectives for pharmaceutical researchers.

Detection and Quantification of Polymorphic MICA and MICB Molecules in Immunoassays: Initial Insights

The MICA and MICB molecules, expressed on the cell membrane in response to cellular stress or cancer transformation, pose significant challenges for immunoassays. They exhibit high sequence and structural similarity, alongside considerable allelic polymorphism, with 291 and 53 known protein sequences, respectively. Some researchers treat MICA and MICB as a unified target because of their structural and functional similarities, while others distinguish between them. However, which approach is superior and under what circumstances remains unknown. Moreover, information about assays' reactivity with MICA and MICB allelic variants is often missing. In this study, we developed 10 monoclonal antibodies (mAbs) and two sandwich ELISAs for the detection and quantification of these molecules. We assembled a panel of recombinant proteins representing the diversity of MICA and MICB in the European population and profiled the reactivities of the mAbs and ELISAs. The performance of these sandwich ELISAs was evaluated using samples from prostate cancer patients and pregnant women experiencing premature rupture of membranes. Our study assessed the impact of MICA and MICB polymorphism on their detection and quantification by immunological methods, providing evidence to support differential or non-differential approaches for their detection.

A novel high-risk model identified by epithelial-mesenchymal transition predicts prognosis and radioresistance in rectal cancer

Many studies have shown that tumor cells that survive radiotherapy are more likely to metastasize, but the underlying mechanism remains unclear. Here we aimed to identify epithelial-mesenchymal transition (EMT)-related key genes, which associated with prognosis and radiosensitivity in rectal cancer. First, we obtained differentially expressed genes by analyzing the RNA expression profiles of rectal cancer retrieved from The Cancer Genome Atlas database, EMT-related genes, and radiotherapy-related databases, respectively. Then, Lasso and Cox regression analyses were used to establish an EMT-related prognosis model (EMTPM) based on the identified independent protective factor Fibulin5 (FBLN5) and independent risk gene EHMT2. The high-EMTPM group exhibited significantly poorer prognosis. Then, we evaluated the signature in an external clinical validation cohort. Through in vivo experiments, we further demonstrated that EMTPM effectively distinguishes radioresistant from radiosensitive patients with rectal cancer. Moreover, individuals in the high-EMTPM group showed increased expression of immune checkpoints compared to their counterparts. Finally, pan-cancer analysis of the EMTPM model also indicated its potential for predicting the prognosis of lung squamous cell carcinoma and breast cancer patients undergoing radiotherapy. In summary, we established a novel predictive model for rectal cancer prognosis and radioresistance based on FBLN5 and EHMT2 expressions, and suggested that immune microenvironment may be involved in the process of radioresistance. This predictive model could be used to select management strategies for rectal cancer.

The Roles of H3K9me3 Writers, Readers, and Erasers in Cancer Immunotherapy

The interplay between cancer and the immune system has captivated researchers for a long time. Recent developments in cancer immunotherapy have substantiated this interest with a significant benefit to cancer patients. Tumor and immune cells are regulated via a wide range of molecular mechanisms involving intricate transcriptional and epigenetic networks. Epigenetic processes influence chromatin structure and accessibility, thus governing gene expression, replication, and DNA damage repair. However, aberrations within epigenetic signatures are frequently observed in cancer. One of the key epigenetic marks is the trimethylation of histone 3 at lysine 9 (H3K9me3), confined mainly within constitutive heterochromatin to suppress DNA accessibility. It is deposited at repetitive elements, centromeric and telomeric loci, as well as at the promoters of various genes. Dysregulated H3K9me3 deposition disrupts multiple pathways, including immune signaling. Consequently, altered H3K9me3 dynamics may modify the efficacy of immunotherapy. Indeed, growing evidence highlights the pivotal roles of various proteins mediating H3K9me3 deposition (SETDB1/2, SUV39H1/2), erasure (KDM3, KDM4 families, KDM7B, LSD1) and interpretation (HP1 proteins, KAP1, CHD4, CDYL, UHRF1) in modulating immunotherapy effectiveness. Here, we review the existing literature to synthesize the available information on the influence of these H3K9me3 writers, erasers, and readers on the response to immunotherapy.

Promising and challenging phytochemicals targeting LC3 mediated autophagy signaling in cancer therapy

BACKGROUND

Phytochemicals possess a wide range of anti-tumor properties, including the modulation of autophagy and regulation of programmed cell death. Autophagy is a critical process in cellular homeostasis and its dysregulation is associated with several pathological conditions, such as cancer, neurodegenerative diseases, and diabetes. In cancer, autophagy plays a dual role by either promoting tumor growth or suppressing it, depending on the cellular context. During autophagy, autophagosomes engulf cytoplasmic components such as proteins and organelles. LC3-II (microtubule-associated protein 1 light chain 3-II) is an established marker of autophagosome formation, making it central to autophagy monitoring in mammals.

OBJECTIVE

To explore the regulatory role of phytochemicals in LC3-mediated autophagy and their potential therapeutic impact on cancer. The review emphasizes the involvement of autophagy in tumor promotion and suppression, particularly focusing on autophagy-related signaling pathways like oxidative stress through the NRF2 pathway, and its implications for genomic stability in cancer development.

METHODS

The review focuses on a comprehensive analysis of bioactive compounds including Curcumin, Celastrol, Resveratrol, Kaempferol, Naringenin, Carvacrol, Farnesol, and Piperine. Literature on these compounds was examined to assess their influence on autophagy, LC3 expression, and tumor-related signaling pathways. A systematic literature search was conducted across databases including PubMed, Scopus, and Web of Science from inception to 2023. Studies were selected from prominent databases, focusing on their roles in cancer diagnosis and therapeutic interventions, particularly in relation to LC3-mediated mechanisms.

RESULTS

Phytochemicals have been shown to modulate autophagy through the regulation of LC3-II levels and autophagic flux in cancer cells. The interaction between autophagy and other cellular pathways such as oxidative stress, inflammation, and epigenetic modulation highlights the complex role of autophagy in tumor biology. For instance, Curcumin and Resveratrol have been reported to either induce or inhibit autophagy depending on cancer type, influencing tumor progression and therapeutic responses.

CONCLUSION

Targeting autophagy through LC3 modulation presents a promising strategy for cancer therapy. The dual role of autophagy in tumor suppression and promotion, however, necessitates careful consideration of the context in which autophagy is induced or inhibited. Future research should aim to delineate these context-specific roles and explore how phytochemicals can be optimized for therapeutic efficacy. Novel therapeutic strategies should focus on the use of bioactive compounds to fine-tune autophagy, thereby maximizing tumor suppression and inducing programmed cell death in cancer cells.

Maternal histone methyltransferases antagonistically regulate monoallelic expression in C. elegans

Undefined epigenetic programs act to probabilistically silence individual autosomal alleles, generating unique individuals, even from genetic clones. This sort of random monoallelic expression can explain variation in traits and diseases that differences in genes and environments cannot. Here, we developed the nematode Caenorhabditis elegans to study monoallelic expression in whole tissues, and defined a developmental genetic regulation pathway. We found maternal H3K9 histone methyltransferase (HMT) SET-25/SUV39/G9a works with HPL-2/HP1 and LIN-61/L3MBTL2 to randomly silence alleles in the intestinal progenitor E-cell of 8-cell embryos to cause monoallelic expression. SET-25 was antagonized by another maternal H3K9 HMT, MET-2/SETDB1, which works with LIN-65/ATF7ZIP and ARLE-14/ARL14EP to prevent monoallelic expression. The HMT-catalytic SET domains of both MET-2 and SET-25 were required for regulating monoallelic expression. Our data support a model wherein SET-25 and MET-2 regulate histones during development to generate patterns of somatic monoallelic expression that are persistent but not heritable.

Regulation of DNA damage-induced HLA class I presentation

Immune checkpoint inhibitors (ICI) are cancer therapies that restore anti-tumor immunity; however, only a small percentage of patients have been completely cured by ICI alone. Multiple approaches in combination with other modalities have been used to improve the efficacy of ICI therapy. Among conventional cancer treatments, radiotherapy or DNA damage-based chemotherapy is a promising candidate as a partner of ICI because DNA damage signaling potentially stimulates immune activities turning the tumor's immune environment into hot tumors. Programmed death-ligand 1 (PD-L1) and human leukocyte antigen class I (HLA-I), which are immune ligands, regulate the balance of anti-tumor immunity in the tumor microenvironment. PD-L1 functions as a brake to suppress cytotoxic T cell activity, whereas HLA-I is an immune accelerator that promotes the downstream of the T cell signaling. Accumulating evidence has demonstrated that DNA damage enhances the presentation of HLA-I on the surface of damaged cells. However, it is unclear how signal transduction in DNA-damaged cells upregulates the presentation of HLA-I with antigens. Our recent study uncovered the mechanism underlying DNA damage-induced HLA-I presentation, which requires polypeptide synthesis through a pioneer round of translation. In this review, we summarize the latest overview of how DNA damage stimulates antigen production presented by HLA-I.

A chimeric antigen receptor uniquely recognizing MICA/B stress proteins provides an effective approach to target solid tumors

BACKGROUND

The advent of chimeric antigen receptor (CAR) T cell therapies has transformed the treatment of hematological malignancies; however, broader therapeutic success of CAR T cells has been limited in solid tumors because of their frequently heterogeneous composition. Stress proteins in the MICA and MICB (MICA/B) family are broadly expressed by tumor cells following DNA damage but are rapidly shed to evade immune detection.

METHODS

We have developed a novel CAR targeting the conserved α3 domain of MICA/B (3MICA/B CAR) and incorporated it into a multiplexed-engineered induced pluripotent stem cell (iPSC)-derived natural killer (NK) cell (3MICA/B CAR iNK) that expressed a shedding-resistant form of the CD16 Fc receptor to enable tumor recognition through two major targeting receptors.

FINDINGS

We demonstrated that 3MICA/B CAR mitigates MICA/B shedding and inhibition via soluble MICA/B while simultaneously exhibiting antigen-specific anti-tumor reactivity across an expansive library of human cancer cell lines. Pre-clinical assessment of 3MICA/B CAR iNK cells demonstrated potent antigen-specific in vivo cytolytic activity against both solid and hematological xenograft models, which was further enhanced in combination with tumor-targeted therapeutic antibodies that activate the CD16 Fc receptor.

CONCLUSIONS

Our work demonstrated 3MICA/B CAR iNK cells to be a promising multi-antigen-targeting cancer immunotherapy approach intended for solid tumors.

FUNDING

Funded by Fate Therapeutics and NIH (R01CA238039).

Epigenetic modulation and prostate cancer: Paving the way for NK cell anti-tumor immunity

Immunoepigenetics is a growing field, as there is mounting evidence on the key role played by epigenetic mechanisms in the regulation of tumor immune cell recognition and control of immune cell anti-tumor responses. Moreover, it is increasingly acknowledgeable a tie between epigenetic regulation and prostate cancer (PCa) development and progression. PCa is intrinsically a cold tumor, with scarce immune cell infiltration and low inflammatory tumor microenvironment. However, Natural Killer (NK) cells, main anti-tumor effector immune cells, have been frequently linked to improved PCa prognosis. The role that epigenetic-related mechanisms might have in regulating both NK cell recognition of PCa tumor cells and NK cell functions in PCa is still mainly unknown. Epigenetic modulating drugs have been showing boundless therapeutic potential as anti-tumor agents, however their role in immune cell regulation and recognition is scarce. In this review, we focused on studies addressing modulation of epigenetic mechanisms involved in NK cell-mediated responses, including both the epigenetic modulation of tumor cell NK ligand expression and NK cell receptor expression and function in different tumor models, highlighting studies in PCa. The integrated knowledge from diverse epigenetic modulation mechanisms promoting NK cell-mediated immunity in various tumor models might open doors for the development of novel epigenetic-based therapeutic options for PCa management.

Radiosensitization effect by HDAC inhibition improves NKG2D-dependent natural killer cytotoxicity in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Radiotherapy (RT) controls HCC unsatisfactorily and temporarily. Histone deacetylase inhibitor (HDACi) is a heterogeneous group of epigenetic therapeutics with promising anticancer effects and synergism in combination with RT. HDACi modulates natural killer (NK) cell ligand expression on tumor cells, and leads to immune evasion of cancer cells. Expressions of NK group 2D (NKG2D) ligands on cancer cells determine the cytotoxic effect by interacting with NKG2D receptor on NK cells. However, the role of NKG2D signaling in HCC upon combined RT and HDACi remains unclear.

Method

In vitro co-culture system with NK cells was tested for human and murine HCC cell lines. Pan-HDACi (panobinostat) and specific HDAC4 knockdown (HDAC4-KD) were used for HDAC inhibition. Clonogenic assay and flow cytometry examined HCC cell survival and NKG2D ligand expression, respectively. Syngeneic mouse model was used to validate the radiosensitizing effect in vivo.

Results

Combined RT and HDACi/HDAC4-KD significantly enhanced NK cell-related cytotoxicity and increased NKG2D ligands, MICA/MICB expressions in human and RAE-1/H60 expressions in murine HCC cells. Delayed tumor growth in vivo by the combinational treatment of RT and HDACi/HDAC4-KD was shown with the associated NKG2D ligand expressions. However, NKG2D receptor did not significantly change among tumors.

Conclusion

Radiosensitizing effect with combined RT and HDAC inhibition increased the expression of NKG2D ligands in HCC cells and enhanced their susceptibility to NK cell-mediated cytotoxicity. These findings imply the potential use of combined RT/HDACi and NK cell-directed immunotherapy.

Value of carbon-ion radiotherapy for early stage non-small cell lung cancer

Carbon-ion radiotherapy (CIRT) is an important part of modern radiotherapy. Compared to conventional photon radiotherapy modalities, CIRT brings two major types of advantages to physical and biological aspects respectively. The physical advantages include a substantial dose delivery to the tumoral area and a minimization of dose damage to the surrounding tissue. The biological advantages include an increase in double-strand breaks (DSBs) in DNA structures, an upturn in oxygen enhancement ratio and an improvement of radiosensitivity compared with X-ray radiotherapy. The two advantages of CIRT are that the therapy not only inflicts major cytotoxic lesions on tumor cells, but it also protects the surrounding tissue. According to annual diagnoses, lung cancer is the second most common cancer worldwide, followed by breast cancer. However, lung cancer is the leading cause of cancer death. Patients with stage I non-small cell lung cancer (NSCLC) who are optimally received the treatment of lobectomy. Some patients with comorbidities or combined cardiopulmonary insufficiency have been shown to be unable to tolerate the treatment when combined with surgery. Consequentially, radiotherapy may be the best treatment option for this patient category. Multiple radiotherapy options are available for these cases, such as stereotactic body radiotherapy (SBRT), volumetric modulated arc therapy (VMAT), and intensity-modulated radiotherapy (IMRT). Although these treatments have brought some clinical benefits to some patients, the resulting adverse events (AEs), which include cardiotoxicity and radiation pneumonia, cannot be ignored. The damage and toxicity to normal tissue also limit the increase of tumor dose. Due to the significant physical and biological advantages brought by CIRT, some toxicity induced by radiotherapy may be avoided with CIRT Bragg Peak. CIRT brought clinical benefits to lung cancer patients, especially geriatric patients. This review introduced the clinical efficacy and research results for non-small cell lung cancer (NSCLC) with CIRT.

The Role of HDACs in the Response of Cancer Cells to Cellular Stress and the Potential for Therapeutic Intervention

Throughout the process of carcinogenesis, cancer cells develop intricate networks to adapt to a variety of stressful conditions including DNA damage, nutrient deprivation, and hypoxia. These molecular networks encounter genomic instability and mutations coupled with changes in the gene expression programs due to genetic and epigenetic alterations. Histone deacetylases (HDACs) are important modulators of the epigenetic constitution of cancer cells. It has become increasingly known that HDACs have the capacity to regulate various cellular systems through the deacetylation of histone and bounteous nonhistone proteins that are rooted in complex pathways in cancer cells to evade death pathways and immune surveillance. Elucidation of the signaling pathways involved in the adaptive responses to cellular stress and the role of HDACs may lead to the development of novel therapeutic agents. In this article, we overview the dominant stress types including metabolic, oxidative, genotoxic, and proteotoxic stress imposed on cancer cells in the context of HDACs, which guide stress adaptation responses. Next, we expose a closer view on the therapeutic interventions and clinical trials that involve HDACs inhibitors, in addition to highlighting the impact of using HDAC inhibitors in combination with stress-inducing agents for the management of cancer and to overcome the resistance to current cancer therapy.

Characterizing HDAC Pathway Copy Number Variation in Pan-Cancer

Background: Histone deacetylase (HDAC) plays a crucial role in regulating the expression and activity of a variety of genes associated with tumor progression and immunotherapeutic processes. The aim of this study was to characterize HDAC pathway copy number variation (CNV) in pan-cancer. Methods: A total of 10,678 tumor samples involving 33 types of tumors from The Cancer Genome Atlas (TCGA) were included in the study. Results: HDAC pathway CNV and CNV gain were identified as prognostic risk factors for pan-cancer species. The differences of tumor characteristics including tumor mutational burden, tumor neoantigen burden, high-microsatellite instability, and microsatellite stable between HDAC pathway CNV altered-type group and wild-type group varied among the various cancer species. In some cancer types, HDAC pathway CNV alteration was positively correlated with loss of heterozygosity, CNV burden, ploidy, and homologous recombination defect score markers, while it was significantly negatively correlated with immune score and stroma score. There were significant differences in immune characteristics such as major histocompatibility complex class I (MHC-I), MHC-II, chemokines, cytolytic-activity, and IFN-γ between the two groups. Immune cycle characteristics varied from one cancer type to another. Conclusion: This study reveals a tumor and immune profile of HDAC pathway CNV as well as its unlimited potential in immune prognosis.

Mapping the biogenesis of forward programmed megakaryocytes from induced pluripotent stem cells

Platelet deficiency, known as thrombocytopenia, can cause hemorrhage and is treated with platelet transfusions. We developed a system for the production of platelet precursor cells, megakaryocytes, from pluripotent stem cells. These cultures can be maintained for >100 days, implying culture renewal by megakaryocyte progenitors (MKPs). However, it is unclear whether the MKP state in vitro mirrors the state in vivo, and MKPs cannot be purified using conventional surface markers. We performed single-cell RNA sequencing throughout in vitro differentiation and mapped each state to its equivalent in vivo. This enabled the identification of five surface markers that reproducibly purify MKPs, allowing us insight into their transcriptional and epigenetic profiles. Last, we performed culture optimization, increasing MKP production. Together, this study has mapped parallels between the MKP states in vivo and in vitro and allowed the purification of MKPs, accelerating the progress of in vitro-derived transfusion products toward the clinic.

G9a: An Emerging Epigenetic Target for Melanoma Therapy

Epigenetic regulation is a crucial component of DNA maintenance and cellular identity. As our understanding of the vast array of proteins that contribute to chromatin accessibility has advanced, the role of epigenetic remodelers in disease has become more apparent. G9a is a histone methyltransferase that contributes to immune cell differentiation and function, neuronal development, and has been implicated in diseases, including cancer. In melanoma, recurrent mutations and amplifications of G9a have led to its identification as a therapeutic target. The pathways that are regulated by G9a provide an insight into relevant biomarkers for patient stratification. Future work is aided by the breadth of literature on G9a function during normal differentiation and development, along with similarities to EZH2, another histone methyltransferase that forms a synthetic lethal relationship with members of the SWI/SNF complex in certain cancers. Here, we review the literature on G9a, its role in melanoma, and lessons from EZH2 inhibitor studies.

Epigenetic regulation of autophagy: A key modification in cancer cells and cancer stem cells

Aberrant epigenetic alterations play a decisive role in cancer initiation and propagation via the regulation of key tumor suppressor genes and oncogenes or by modulation of essential signaling pathways. Autophagy is a highly regulated mechanism required for the recycling and degradation of surplus and damaged cytoplasmic constituents in a lysosome dependent manner. In cancer, autophagy has a divergent role. For instance, autophagy elicits tumor promoting functions by facilitating metabolic adaption and plasticity in cancer stem cells (CSCs) and cancer cells. Moreover, autophagy exerts pro-survival mechanisms to these cancerous cells by influencing survival, dormancy, immunosurveillance, invasion, metastasis, and resistance to anti-cancer therapies. In addition, recent studies have demonstrated that various tumor suppressor genes and oncogenes involved in autophagy, are tightly regulated via different epigenetic modifications, such as DNA methylation, histone modifications and non-coding RNAs. The impact of epigenetic regulation of autophagy in cancer cells and CSCs is not well-understood. Therefore, uncovering the complex mechanism of epigenetic regulation of autophagy provides an opportunity to improve and discover novel cancer therapeutics. Subsequently, this would aid in improving clinical outcome for cancer patients. In this review, we provide a comprehensive overview of the existing knowledge available on epigenetic regulation of autophagy and its importance in the maintenance and homeostasis of CSCs and cancer cells.

Modulation of immune responses by DNA damage signaling

An accumulation of evidence indicates the importance of DNA damage signaling in modulating immune responses. Indeed, understanding the mechanism that underlies signal transduction originating from DNA damage is vital to overcoming refractory cancer, particularly when cancer immune therapy is applied in combination with DNA damage-dependent radio/chemotherapy. In addition, immune-associated responses to such signals can aggravate the symptoms of infections, allergies, autoimmune disease, and aging. In this review, we discuss how cells transduce signals, triggered by DNA damage, from their origins to neighboring cells and how this affects immune and inflammatory responses.

Rationale of combination of anti-PD-1/PD-L1 antibody therapy and radiotherapy for cancer treatment

Significant technological advances in radiotherapy have been made in the past few decades. High-precision radiotherapy has recently become popular and is contributing to improvements in the local control of the irradiated target lesions and the reduction of adverse effects. Accordingly, for long-term survival, the importance of systemic cancer control, including at non-irradiated sites, is growing. Toward this challenge, the treatment methods in which anti-PD-1/PD-L1 antibodies that exert systemic effects by restoring anti-tumour immunity are combined with radiotherapy has attracted attention in recent years. Previous studies have reported the activation of anti-tumour immunity by radiotherapy, which simultaneously elevates PD-L1 expression, suggesting a potential for combination therapy. Radiotherapy induces so-called ‘immunogenic cell death’, which involves cell surface translocation of calreticulin and extracellular release of high-mobility group protein box 1 (HMGB-1) and adenosine-5′-triphosphate (ATP). Furthermore, radiotherapy causes immune activation via MHC class I upregulation and cGAS–STING pathway. In contrast, induction of immunosuppressive lymphocytes and the release of immunosuppressive cytokines and chemokines by radiotherapy contribute to immunosuppressive reactions. In this article, we review immune responses induced by radiotherapy as well as previous reports to support the rationale of combination of radiotherapy and anti-PD-1/PD-L1 antibodies. A number of preclinical and clinical studies have shown the efficacy of radiotherapy combined with immune checkpoint inhibition, hence combination therapy is considered to be an important future strategy for cancer treatment.

High glucose promotes pancreatic cancer cells to escape from immune surveillance via AMPK-Bmi1-GATA2-MICA/B pathway

Background

Modulation of cell surface expression of MHC class I chain-related protein A/B (MICA/B) has been proven to be one of the mechanisms by which tumor cells escape from NK cell-mediated killing. Abnormal metabolic condition, such as high glucose, may create a cellular stress milieu to induce immune dysfunction. Hyperglycemia is frequently presented in the majority of pancreatic cancer patients and is associated with poor prognosis. In this study, we aimed to detect the effects of high glucose on NK cell-mediated killing on pancreatic cancer cells through reduction of MICA/B expression.

Methods

The lysis of NK cells on pancreatic cancer cells were compared at different glucose concentrations through lactate dehydrogenase release assay. Then, qPCR, Western Blot, Flow cytometry and Immunofluorescence were used to identify the effect of high glucose on expression of MICA/B, Bmi1, GATA2, phosphorylated AMPK to explore the underlying mechanisms in the process. Moreover, an animal model with diabetes mellitus was established to explore the role of high glucose on NK cell-mediated cytotoxicity on pancreatic cancer in vivo.

Results

In our study, high glucose protects pancreatic cancer from NK cell-mediated killing through suppressing MICA/B expression. Bmi1, a polycomb group (PcG) protein, was found to be up-regulated by high glucose, and mediated the inhibition of MICA/B expression through promoting GATA2 in pancreatic cancer. Moreover, high glucose inhibited AMP-activated protein kinase signaling, leading to high expression of Bmi1.

Conclusion

Our findings identify that high glucose may promote the immune escape of pancreatic cancer cells under hyperglycemic tumor microenvironment. In this process, constitutive activation of AMPK-Bmi1-GATA2 axis could mediate MICA/B inhibition, which may serve as a therapeutic target for further intervention of pancreatic cancer immune evasion.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1209-9) contains supplementary material, which is available to authorized users.

Novel Approaches to Improve the Efficacy of Immuno-Radiotherapy

Radiotherapy (RT) has been applied for decades as a treatment modality in the management of various types of cancer. Ionizing radiation induces tumor cell death, which in turn can either elicit protective anti-tumor immune responses or immunosuppression in the tumor micromilieu that contributes to local tumor recurrence. Immunosuppression is frequently accompanied by the attraction of immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs), M2 tumor-associated macrophages (TAMs), T regulatory cells (Tregs), N2 neutrophils, and by the release of immunosuppressive cytokines (TGF-β, IL-10) and chemokines. Immune checkpoint pathways, particularly of the PD-1/PD-L1 axis, have been determined as key regulators of cancer immune escape. While IFN-dependent upregulation of PD-L1 has been extensively investigated, up-to-date studies indicated the importance of DNA damage signaling in the regulation of PD-L1 expression following RT. DNA damage dependent PD-L1 expression is upregulated by ATM/ATR/Chk1 kinase activities and cGAS/STING-dependent pathway, proving the role of DNA damage signaling in PD-L1 induced expression. Checkpoint blockade immunotherapies (i.e., application of anti-PD-1 and anti-PD-L1 antibodies) combined with RT were shown to significantly improve the objective response rates in therapy of various primary and metastatic malignancies. Further improvements in the therapeutic potential of RT are based on combinations of RT with other immunotherapeutic approaches including vaccines, cytokines and cytokine inducers, and an adoptive immune cell transfer (DCs, NK cells, T cells). In the current review we provide immunological rationale for a combination of RT with various immunotherapies as well as analysis of the emerging preclinical evidences for these therapies.

Ex Vivo Expanded Human Vγ9Vδ2 T-Cells Can Suppress Epithelial Ovarian Cancer Cell Growth

γδ-T-cells have attracted attention because of their potent cytotoxicity towards tumors. Most γδ-T-cells become activated via a major histocompatibility complex (MHC)-independent pathway by the interaction of their receptor, Natural Killer Group 2 Member D (NKG2D) with the tumor-specific NKG2D ligands, including MHC class I-related chain A/B (MICA/B) and UL16-binding proteins (ULBPs), to kill tumor cells. However, despite their potent antitumor effects, the treatment protocols specifically targeting ovarian tumors require further improvements. Ovarian cancer is one of the most lethal and challenging female malignancies worldwide because of delayed diagnoses and resistance to traditional chemotherapy. In this study, we successfully enriched and expanded γδ-T-cells up to ~78% from peripheral blood mononuclear cells (PBMCs) with mostly the Vγ9Vδ2-T-cell subtype in the circulation. We showed that expanded γδ-T-cells alone exerted significant cytotoxic activities towards specific epithelial-type OVCAR3 and HTB75 cells, whereas the combination of γδ-T cells and pamidronate (PAM), a kind of aminobisphosphonates (NBPs), showed significantly enhanced cytotoxic activities towards all types of ovarian cancer cells in vitro. Furthermore, in tumor xenografts of immunodeficient NSG mice, γδ-T-cells not only suppressed tumor growth but also completely eradicated preexisting tumors with an initial size of ~5 mm. Thus, we concluded that γδ-T-cells alone possess dramatic cytotoxic activities towards epithelial ovarian cancers both in vitro and in vivo. These results strongly support the potential of clinical immunotherapeutic application of γδ-T-cells to treat this serious female malignancy.

Targeted cancer cell ablation in mice by an α-particle-emitting astatine-211-labeled antibody against major histocompatibility complex class I chain-related protein A and B

Major histocompatibility complex class I chain-related protein A and B (MICA/B) are ligands of the immune receptor, natural-killer group 2 member D. MICA/B expression is often found in several types of cancer but is restricted in normal tissues. Here, we show that an α-particle emitting astatine-211 (²¹¹At)-labeled antibody targeting MICA/B (²¹¹At-anti MICA/B Ab) efficiently ablates cancer cells in vitro and in vivo. We generated ²¹¹At-anti MICA/B Ab, an anti-MICA/B antibody conjugated with a highly cytotoxic α-particle emitting radionuclide ²¹¹At. ²¹¹At-anti MICA/B Ab binds to human osteosarcoma SaOS2 and U2OS cells that exhibit high levels of MICA/B expression and efficiently kills those cells in vitro. Biodistribution analysis using xenograft mouse models of HCT116 p53^-/- positive for MICA/B expression, showed increased ²¹¹At in the xenografts for up to 22 h after injection as time proceeded. A single dose of ²¹¹At-anti MICA/B Ab (1 MBq) showed significant reduction in the tumor growth rate of HCT116 p53^-/- xenografts compared to ²¹¹At-labeled mouse IgG (1 MBq) at 21 days after injection. No body weight loss and erythrocytopenia was evident in mice that received ²¹¹At-anti MICA/B. Leukocytopenia and thrombocytopenia were observed within a week after ²¹¹At-anti MICA/B injection, but counts of red blood cells and platelets were recovered to control levels at about 3-4 weeks after injection. Taken together, these data strongly demonstrate that targeted α-particle therapy using ²¹¹At-anti-MICA/B Ab emitting highly cytotoxic α-particles is a potential new therapeutic option for several types of cancer.

Kaempferol induces autophagic cell death via IRE1-JNK-CHOP pathway and inhibition of G9a in gastric cancer cells

Kaempferol, a flavonoid, found in traditional medicine, fruits, and vegetables, and an HDAC inhibitor, is a powerful anti-cancer reagent against various cancer cell lines. However, detailed mechanisms involved in the treatment of gastric cancer (GC) using kaempferol are not fully understood. In our study, we investigated the biological activity and molecular mechanism involved in kaempferol-mediated treatment of GC. Kaempferol promoted autophagy and cell death, and increased LC3-I to LC3-II conversion and the downregulation of p62 in GC. Furthermore, our results showed that kaempferol induces autophagic cell death via the activation of the IRE1-JNK-CHOP signaling, indicating ER stress response. Indeed, the inhibition of ER stress suppressed kaempferol-induced autophagy and conferred prolonged cell survival, indicating autophagic cell death. We further showed that kaempferol mediates epigenetic change via the inhibition of G9a (HDAC/G9a axis) and also activates autophagic cell death. Taken together, our findings indicate that kaempferol activates the IRE1-JNK-CHOP signaling from cytosol to nucleus, and G9a inhibition activates autophagic cell death in GC cells.

NKG2D and its ligands in cancer

NKG2D is an activating immune receptor expressed by NK and effector T cells. Induced expression of NKG2D ligand on tumor cell surface during oncogenic insults renders cancer cells susceptible to immune destruction. In advanced human cancers, tumor cells shed NKG2D ligand to produce an immune soluble form as a means of immune evasion. Soluble NKG2D ligands have been associated with poor clinical prognosis in cancer patients. Harnessing NKG2D pathway is considered a viable avenue in cancer immunotherapy over recent years. In this review, we will discuss the progress and perspectives.

Unconventional Approaches to Modulating the Immunogenicity of Tumor Cells

For several years, it has been known that histone deacetylase inhibitors have the potential to alter the immunogenicity of tumor cells exposed to checkpoint inhibitory immunotherapy antibodies. HDAC inhibitors can rapidly reduce expression of PD-L1 and increase expression of MHCA in various tumor types that subsequently facilitate the antitumor actions of checkpoint inhibitors. Recently, we have discovered that drug combinations which cause a rapid and intense autophagosome formation also can modulate the expression of HDAC proteins that control tumor cell immunogenicity via their regulation of PD-L1 and MHCA. These drug combinations, in particular those using the irreversible ERBB1/2/4 inhibitor neratinib, can result in parallel in the internalization of growth factor receptors as well as fellow-traveler proteins such as mutant K-RAS and mutant N-RAS into autophagosomes. The drug-induced autophagosomes contain HDAC proteins/signaling proteins whose expression is subsequently reduced by lysosomal degradation processes. These findings argue that cancer therapies which strongly promote autophagosome formation and autophagic flux may facilitate the subsequent use of additional antitumor modalities using checkpoint inhibitor antibodies.