Reversible epigenetic alterations regulate class I HLA loss in prostate cancer

Prostate cancer epigenetics - from pathophysiology to clinical application

Prostate cancer is a multifactorial disease influenced by various molecular features. Over the past decades, epigenetics, which is the study of changes in gene expression without altering the DNA sequence, has been recognized as a major driver of this disease. In the past 50 years, advancements in technological tools to characterize the epigenome have highlighted crucial roles of epigenetic mechanisms throughout the entire spectrum of prostate cancer, from initiation to progression, including localized disease, metastatic dissemination, castration resistance and neuroendocrine transdifferentiation. Substantial advances in the understanding of epigenetic mechanisms in the pathophysiology of prostate cancer have been carried out, but translating preclinical achievements into clinical practice remains challenging. Ongoing research and biomarker-oriented clinical trials are expected to increase the likelihood of successfully integrating epigenetics into prostate cancer clinical management.

Mechanisms of Low MHC I Expression and Strategies for Targeting MHC I with Small Molecules in Cancer Immunotherapy

Major histocompatibility complex (MHC) class I load antigens and present them on the cell surface, which transduces the tumor-associated antigens to CD8+ T cells, activating the acquired immune system. However, many tumors downregulate MHC I expression to evade immune surveillance. The low expression of MHC I not only reduce recognition by- and cytotoxicity of CD8+ T cells, but also seriously weakens the anti-tumor effect of immunotherapy by restoring CD8+ T cells, such as immune checkpoint inhibitors (ICIs). Accumulated evidence suggested that restoring MHC I expression is an effective strategy for enhancing tumor immunotherapy. This review focuses on mechanisms underlying MHC I downregulation include gene deletion and mutation, transcriptional inhibition, reduced mRNA stability, increased protein degradation, and disruption of endocytic trafficking. We also provide a comprehensive review of small molecules that restore or upregulate MHC I expression, as well as clinical trials involving the combination of ICIs and these small molecule drugs.

Chromatin accessibility: biological functions, molecular mechanisms and therapeutic application

The dynamic regulation of chromatin accessibility is one of the prominent characteristics of eukaryotic genome. The inaccessible regions are mainly located in heterochromatin, which is multilevel compressed and access restricted. The remaining accessible loci are generally located in the euchromatin, which have less nucleosome occupancy and higher regulatory activity. The opening of chromatin is the most important prerequisite for DNA transcription, replication, and damage repair, which is regulated by genetic, epigenetic, environmental, and other factors, playing a vital role in multiple biological progresses. Currently, based on the susceptibility difference of occupied or free DNA to enzymatic cleavage, solubility, methylation, and transposition, there are many methods to detect chromatin accessibility both in bulk and single-cell level. Through combining with high-throughput sequencing, the genome-wide chromatin accessibility landscape of many tissues and cells types also have been constructed. The chromatin accessibility feature is distinct in different tissues and biological states. Research on the regulation network of chromatin accessibility is crucial for uncovering the secret of various biological processes. In this review, we comprehensively introduced the major functions and mechanisms of chromatin accessibility variation in different physiological and pathological processes, meanwhile, the targeted therapies based on chromatin dynamics regulation are also summarized.

Regional and intratumoral adoptive T-cell therapy

Adoptive T-cell therapies (ACTs) including tumor-infiltrating lymphocytes and engineered T cells (transgenic T-cell receptor and chimeric antigen receptor T cells), have made an important impact in the field of cancer treatment over the past years. Most of these therapies are typically administered systemically in approaches that facilitate the elimination of hematologic malignancies. Therapeutical efficacy against solid tumors, however, with the exception of tumor-infiltrating lymphocytes against melanoma, remains limited due to several barriers preventing lymphocyte access to the tumor bed. Building upon the experience of regional administration in other immunotherapies, the regional administration of adoptive cell therapies is being assessed to overcome this challenge, granting a first round of access of the transferred T cells to the tumor niche and thereby ensuring their activation and expansion. Intralesional and intracavitary routes of delivery have been tested with promising antitumor objective responses in preclinical and clinical studies. Additionally, several strategies are being developed to further improve T-cell activity after reinfusing them back to the patient such as combinations with other immunotherapy agents or direct engineering of the transferred T cells, achieving long-term immune memory. Clinical trials testing different regional adoptive T-cell therapies are ongoing but some issues related to methodology of administration and correct selection of the target antigen to avoid on-target/off-tumor side-effects need to be further evaluated and improved. Herein, we discuss the current preclinical and clinical landscape of intratumoral and locoregional delivery of adoptive T-cell therapies.

The Immune Microenvironment in Prostate Cancer: A Comprehensive Review

BACKGROUND

Prostate cancer (PCa) is a malignancy with significant immunosuppressive properties and limited immune activation. This immunosuppression is linked to reduced cytotoxic T cell activity, impaired antigen presentation, and elevated levels of immunosuppressive cytokines and immune checkpoint molecules. Studies demonstrate that cytotoxic CD8+ T cell infiltration correlates with improved survival, while increased regulatory T cells (Tregs) and tumor-associated macrophages (TAMs) are associated with worse outcomes and therapeutic resistance. Th1 cells are beneficial, whereas Th17 cells, producing interleukin-17 (IL-17), contribute to tumor progression. Tumor-associated neutrophils (TANs) and immune checkpoint molecules, such as PD-1/PD-L1 and T cell immunoglobulin-3 (TIM-3) are also linked to advanced stages of PCa. Chemotherapy holds promise in converting the "cold" tumor microenvironment (TME) to a "hot" one by depleting immunosuppressive cells and enhancing tumor immunogenicity.

SUMMARY

This comprehensive review examines the immune microenvironment in PCa, focusing on the intricate interactions between immune and tumor cells in the TME. It highlights how TAMs, Tregs, cytotoxic T cells, and other immune cell types contribute to tumor progression or suppression and how PCa's low immunogenicity complicates immunotherapy.

KEY MESSAGES

The infiltration of cytotoxic CD8+ T cells and Th1 cells correlates with better outcomes, while elevated T regs and TAMs promote tumor growth, metastasis, and resistance. TANs and natural killer (NK) cells exhibit dual roles, with higher NK cell levels linked to better prognoses. Immune checkpoint molecules like PD-1, PD-L1, and TIM-3 are associated with advanced disease. Chemotherapy can improve tumor immunogenicity by depleting T regs and myeloid-derived suppressor cells, offering therapeutic promise.

MHC Hammer reveals genetic and non-genetic HLA disruption in cancer evolution

Disruption of the class I human leukocyte antigen (HLA) molecules has important implications for immune evasion and tumor evolution. We developed major histocompatibility complex loss of heterozygosity (LOH), allele-specific mutation and measurement of expression and repression (MHC Hammer). We identified extensive variability in HLA allelic expression and pervasive HLA alternative splicing in normal lung and breast tissue. In lung TRACERx and lung and breast TCGA cohorts, 61% of lung adenocarcinoma (LUAD), 76% of lung squamous cell carcinoma (LUSC) and 35% of estrogen receptor-positive (ER+) cancers harbored class I HLA transcriptional repression, while HLA tumor-enriched alternative splicing occurred in 31%, 11% and 15% of LUAD, LUSC and ER+ cancers. Consistent with the importance of HLA dysfunction in tumor evolution, in LUADs, HLA LOH was associated with metastasis and LUAD primary tumor regions seeding a metastasis had a lower effective neoantigen burden than non-seeding regions. These data highlight the extent and importance of HLA transcriptomic disruption, including repression and alternative splicing in cancer evolution.

Left out in the cold: Moving beyond hormonal therapy for the treatment of immunologically cold prostate cancer with CAR T cell immunotherapies

Prostate cancer is primarily hormone-dependent, and medical treatments have focused on inhibiting androgen biosynthesis or signaling through various approaches. Despite significant advances with the introduction of androgen receptor signalling inhibitors (ARSIs), patients continue to progress to castration-resistant prostate cancer (CRPC), highlighting the need for targeted therapies that extend beyond hormonal blockade. Chimeric Antigen Receptor (CAR) T cells and other engineered immune cells represent a new generation of adoptive cellular therapies. While these therapies have significantly enhanced outcomes for patients with hematological malignancies, ongoing research is exploring the broader use of CAR T therapy in solid tumors, including advanced prostate cancer. In general, CAR T cell therapies are less effective against solid cancers with the immunosuppressive tumor microenvironment hindering T cell infiltration, activation and cytotoxicity following antigen recognition. In addition, inherent tumor heterogeneity exists in patients with advanced prostate cancer that may prevent durable therapeutic responses using single-target agents. These barriers must be overcome to inform clinical trial design and improve treatment efficacy. In this review, we discuss the innovative and rationally designed strategies under investigation to improve the clinical translation of cellular immunotherapy in prostate cancer and maximise therapeutic outcomes for these patients.

Epigenetic silencing of ZIC4 unveils a potential tumor suppressor role in pediatric choroid plexus carcinoma

Zic family member ZIC4 is a transcription factor that has been shown to be silenced in several cancers. However, understanding the regulation and function of ZIC4 in pediatric choroid plexus tumors (CPTs) remained limited. This study employed data mining and bioinformatics analysis to investigate the DNA methylation status of ZIC4 in CPTs and its correlation with patient survival. Our results unveiled ZIC4 methylation as a segregating factor, dividing CPT cohorts into two clusters, with hyper-methylation linked to adverse prognosis. Hyper-methylation of ZIC4 was confirmed in a choroid plexus carcinoma-derived cell line (CCHE-45) by bisulfite sequencing. Furthermore, our study demonstrated that demethylating agent and a histone methyltransferase inhibitor could reverse ZIC4 silencing. RNA sequencing and proteomic analysis showed that ZIC4 over-expression influenced genes and proteins involved in immune response, antigen processing and presentation, endoplasmic reticulum stress, and metabolism. Functionally, re-expressing ZIC4 negatively impacted cell proliferation and migration. Ultimately, these findings underscore ZIC4 hyper-methylation as a prognostic marker in CPTs and shed light on potential mechanisms underlying its tumor suppressor role in CPC. This insight paves the way for novel therapeutic targets in treating aggressive CPTs.

Clinically Relevant Humanized Mouse Models of Metastatic Prostate Cancer Facilitate Therapeutic Evaluation

There is tremendous need for improved prostate cancer models. Anatomically and developmentally, the mouse prostate differs from the human prostate and does not form tumors spontaneously. Genetically engineered mouse models lack the heterogeneity of human cancer and rarely establish metastatic growth. Human xenografts are an alternative but must rely on an immunocompromised host. Therefore, we generated prostate cancer murine xenograft models with an intact human immune system (huNOG and huNOG-EXL mice) to test whether humanizing tumor-immune interactions would improve modeling of metastatic prostate cancer and the impact of androgen receptor-targeted and immunotherapies. These mice maintain multiple human immune cell lineages, including functional human T-cells and myeloid cells. Implications: To the best of our knowledge, results illustrate the first model of human prostate cancer that has an intact human immune system, metastasizes to clinically relevant locations, responds appropriately to standard-of-care hormonal therapies, and can model both an immunosuppressive and checkpoint-inhibition responsive immune microenvironment.

Immunological hide-and-seek: epigenetically reprogrammed cancer cells and the dynamics of CD8+ T cells

Cancer remains a global health burden, shaped by both genetic mutations and epigenetic dysregulation. Epigenetic alteration plays a pivotal role in tumorigenesis, immune response modulation, and the emergence of treatment resistance. This review emphasizes the intricate interplay between epigenetically reprogrammed cancer cells and the tumor microenvironment (TME), a relationship central to the immunoediting concept, which encompasses elimination, equilibrium, and escape phases. This review highlights the significance of CD8+ T cells as potent anticancer agents and discusses the mechanisms by which tumor cells evade immune surveillance and evolve resistance to immunotherapy. Such evasion entails the regulation of inhibitory molecules, antigen presentation machinery, and cytokine milieu. Furthermore, this review explores the complex dynamics culminating in CD8+ T cell dysfunction within the TME. In summary, this work offers insights into the indispensable role of epigenetic mechanisms in bolstering cancer cell survival amidst immunological challenges within the TME.

βA3/A1-crystallin is an epigenetic regulator of histone deacetylase 3 (HDAC3) in the retinal pigmented epithelial (RPE) cells

The retinal pigmented epithelial (RPE) cells maintain retinal homeostasis, and alterations in their function contribute to non-exudative age-related macular degeneration (AMD) 1,2 . Here, we explore the intricate relationship between RPE cells, epigenetic modifications, and the development of AMD. Importantly, the study reveals a substantial decrease in histone deacetylase 3 (HDAC3) activity and elevated histone acetylation in the RPE of human AMD donor eyes. To investigate epigenetic mechanisms in AMD development, we used a mouse model with RPE-specific Cryba1 knockout 3-5 , revealing that the loss of βA3/A1-crystallin selectively reduces HDAC3 activity, resulting in increased histone acetylation. βA3/A1-crystallin activates HDAC3 by facilitating its interaction with the casein kinase II (CK2) and phosphorylating HDAC3, as well as by regulating intracellular InsP6 (phytic acid) levels, required for activating HDAC3. These findings highlight a novel function of βA3/A1-crystallin as an epigenetic regulator of HDAC3 in the RPE cells and provide insights into potential therapeutic strategies in non-exudative AMD.

Assessment of cancer cell-expressed HLA class I molecules and their immunopathological implications

Immunotherapy using immune checkpoint inhibitors (ICIs) has shown superior efficacy compared with conventional chemotherapy in certain cancer types, establishing immunotherapy as the fourth standard treatment alongside surgical intervention, chemotherapy, and radiotherapy. In cancer immunotherapy employing ICIs, CD8-positive cytotoxic T lymphocytes are recognized as the primary effector cells. For effective clinical outcomes, it is essential that the targeted cancer cells express HLA class I molecules to present antigenic peptides derived from the tumor. However, cancer cells utilize various mechanisms to downregulate or lose HLA class I molecules from their surface, resulting in evasion from immune surveillance. Correlations between prognosis and the integrity of HLA class I molecules expressed by cancer cells have been consistently found across different types of cancer. This paper provides an overview of the regulatory mechanisms of HLA class I molecules and their role in cancer immunotherapy, with a particular emphasis on the significance of utilizing pathological tissues to evaluate HLA class I molecules expressed in cancer cells.

Moving toward improved immune checkpoint immunotherapy for advanced prostate cancer

Human prostate cancer is a heterogenous malignancy that responds poorly to immunotherapy targeting immune checkpoints. The immunosuppressive tumor microenvironment that is typical of human prostate cancer has been the main obstacle to these treatments. The effectiveness of these therapies is also hindered by acquired resistance, leading to slow progress in prostate cancer immunotherapy. Results from the highly anticipated late-stage clinical trials of PD-1/PD-L1 immune checkpoint blockade in patients with advanced prostate cancer have highlighted some of the obstacles to immunotherapy. Despite the setbacks, there is much that has been learned about the mechanisms that drive resistance, and new strategies are being developed and tested. Here, we review the status of immune checkpoint blockade and the immunosuppressive tumor microenvironment and discuss factors contributing to innate and adaptive resistance to immune checkpoint blockade within the context of prostate cancer. We then examine current strategies aiming to overcome these challenges as well as prospects.

Epigenetic therapy: Research progress of decitabine in the treatment of solid tumors

Decitabine's early successful therapeutic outcomes in hematologic malignancies have led to regulatory approvals from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for addressing myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). These approvals have sparked keen interest in exploring the potential of decitabine for treating solid tumors. Continuous preclinical and clinical trials have proved that low doses of decitabine also bring benefits in treating solid tumors, and various proposed mechanisms attempt to explain the potential efficacy. It is important to note that the application of decitabine in solid tumors is still considered investigational. This article reviews the application mechanism and current status of decitabine in the treatment of solid tumors.

Divergent immune microenvironments in two tumor nodules from a patient with mismatch repair-deficient prostate cancer

Patients with prostate cancer (PC) generally do not respond favorably to immune checkpoint inhibitors, which may be due to a low abundance of tumor-infiltrating lymphocytes even when mutational load is high. Here, we identified a patient who presented with high-grade primary prostate cancer with two adjacent tumor nodules. While both nodules were mismatch repair-deficient (MMRd), exhibited pathogenic MSH2 and MSH6 alterations, had a high tumor mutational burden (TMB), and demonstrated high microsatellite instability (MSI), they had markedly distinct immune phenotypes. The first displayed a dense infiltrate of lymphocytes ("hot nodule"), while the second displayed significantly fewer infiltrating lymphocytes ("cold nodule"). Whole-exome DNA analysis found that both nodules shared many identical mutations, indicating that they were derived from a single clone. However, the cold nodule appeared to be sub-clonal relative to the hot nodule, suggesting divergent evolution of the cold nodule from the hot nodule. Whole-transcriptome RNA analysis found that the cold nodule demonstrated lower expression of genes related to antigen presentation (HLA) and, paradoxically, classical tumor immune tolerance markers such as PD-L1 (CD274) and CTLA-4. Immune cell deconvolution suggested that the hot nodule was enriched not only in CD8+ and CD4 + T lymphocytes, but also in M1 macrophages, activated NK cells, and γδ T cells compared to the cold nodule. This case highlights that MMRd/TMB-high PC can evolve to minimize an anti-tumor immune response, and nominates downregulation of antigen presentation machinery (HLA loss) as a potential mechanism of adaptive immune evasion in PC.

FASN Gene Methylation is Associated with Fatty Acid Synthase Expression and Clinical-genomic Features of Prostate Cancer

Fatty acid synthase (FASN) catalyzes the synthesis of long-chain saturated fatty acids and is overexpressed during prostatic tumorigenesis, where it is the therapeutic target in several ongoing trials. However, the mechanism of FASN upregulation in prostate cancer remains unclear. Here, we examine FASN gene CpG methylation pattern by InfiniumEPIC profiling and whole-genome bisulfite sequencing across multiple racially diverse primary and metastatic prostate cancer cohorts, comparing with FASN protein expression as measured by digitally quantified IHC assay and reverse phase protein array analysis or FASN gene expression. We demonstrate that the FASN gene body is hypomethylated and overexpressed in primary prostate tumors compared with benign tissue, and FASN gene methylation is significantly inversely correlated with FASN protein or gene expression in both primary and metastatic prostate cancer. Primary prostate tumors with ERG gene rearrangement have increased FASN expression and we find evidence of FASN hypomethylation in this context. FASN expression is also significantly increased in prostate tumors from carriers of the germline HOXB13 G84E mutation compared with matched controls, consistent with a report that HOXB13 may contribute to epigenetic regulation of FASN in vitro. However, in contrast to previous studies, we find no significant association of FASN expression or methylation with self-identified race in models that include ERG status across two independent primary tumor cohorts. Taken together, these data support a potential epigenetic mechanism for FASN regulation in the prostate which may be relevant for selecting patients responsive to FASN inhibitors.

SIGNIFICANCE

Here, we leverage multiple independent primary and metastatic prostate cancer cohorts to demonstrate that FASN gene body methylation is highly inversely correlated with FASN gene and protein expression. This finding may shed light on epigenetic mechanisms of FASN regulation in prostate cancer and provides a potentially useful biomarker for selecting patients in future trials of FASN inhibitors.

AMG 509 (Xaluritamig), an Anti-STEAP1 XmAb 2+1 T-cell Redirecting Immune Therapy with Avidity-Dependent Activity against Prostate Cancer

The tumor-associated antigen STEAP1 is a potential therapeutic target that is expressed in most prostate tumors and at increased levels in metastatic castration-resistant prostate cancer (mCRPC). We developed a STEAP1-targeted XmAb 2+1 T-cell engager (TCE) molecule, AMG 509 (also designated xaluritamig), that is designed to redirect T cells to kill prostate cancer cells that express STEAP1. AMG 509 mediates potent T cell-dependent cytotoxicity of prostate cancer cell lines in vitro and promotes tumor regression in xenograft and syngeneic mouse models of prostate cancer in vivo. The avidity-driven activity of AMG 509 enables selectivity for tumor cells with high STEAP1 expression compared with normal cells. AMG 509 is the first STEAP1 TCE to advance to clinical testing, and we report a case study of a patient with mCRPC who achieved an objective response on AMG 509 treatment.

SIGNIFICANCE

Immunotherapy in prostate cancer has met with limited success due to the immunosuppressive microenvironment and lack of tumor-specific targets. AMG 509 provides a targeted immunotherapy approach to engage a patient's T cells to kill STEAP1-expressing tumor cells and represents a new treatment option for mCRPC and potentially more broadly for prostate cancer. See related commentary by Hage Chehade et al., p. 20. See related article by Kelly et al., p. 76. This article is featured in Selected Articles from This Issue, p. 5.

Targeting MHC-I molecules for cancer: function, mechanism, and therapeutic prospects

The molecules of Major histocompatibility class I (MHC-I) load peptides and present them on the cell surface, which provided the immune system with the signal to detect and eliminate the infected or cancerous cells. In the context of cancer, owing to the crucial immune-regulatory roles played by MHC-I molecules, the abnormal modulation of MHC-I expression and function could be hijacked by tumor cells to escape the immune surveillance and attack, thereby promoting tumoral progression and impairing the efficacy of cancer immunotherapy. Here we reviewed and discussed the recent studies and discoveries related to the MHC-I molecules and their multidirectional functions in the development of cancer, mainly focusing on the interactions between MHC-I and the multiple participators in the tumor microenvironment and highlighting the significance of targeting MHC-I for optimizing the efficacy of cancer immunotherapy and a deeper understanding of the dynamic nature and functioning mechanism of MHC-I in cancer.

Clinically relevant humanized mouse models of metastatic prostate cancer to evaluate cancer therapies

There is tremendous need for improved prostate cancer (PCa) models. The mouse prostate does not spontaneously form tumors and is anatomically and developmentally different from the human prostate. Engineered mouse models lack the heterogeneity of human cancer and rarely establish metastatic growth. Human xenografts represent an alternative but rely on an immunocompromised host. Accordingly, we generated PCa murine xenograft models with an intact human immune system (huNOG and huNOG-EXL mice) to test whether humanizing tumor-immune interactions would improve modeling of metastatic PCa and the impact of hormonal and immunotherapies. These mice maintain multiple human cell lineages, including functional human T-cells and myeloid cells. In 22Rv1 xenografts, subcutaneous tumor size was not significantly altered across conditions; however, metastasis to secondary sites differed in castrate huNOG vs background-matched immunocompromised mice treated with enzalutamide (enza). VCaP xenograft tumors showed decreases in growth with enza and anti-Programed-Death-1 treatments in huNOG mice, and no effect was seen with treatment in NOG mice. Enza responses in huNOG and NOG mice were distinct and associated with increased T-cells within tumors of enza treated huNOG mice, and increased T-cell activation. In huNOG-EXL mice, which support human myeloid development, there was a strong population of immunosuppressive regulatory T-cells and Myeloid-Derived-Suppressor-Cells (MDSCs), and enza treatment showed no difference in metastasis. Results illustrate, to our knowledge, the first model of human PCa that metastasizes to clinically relevant locations, has an intact human immune system, responds appropriately to standard-of-care hormonal therapies, and can model both an immunosuppressive and checkpoint-inhibition responsive immune microenvironment.

Tumor acidity-activatable macromolecule autophagy inhibitor and immune checkpoint blockade for robust treatment of prostate cancer

Immune checkpoint blockade (ICB) antibody such as anti-PD-L1 (aPD-L1) activates cytotoxic T cells (CTLs) to combat cancer, but they showed poor efficacy in prostate cancer (PCa). Lysosome-dependent autophagy is utilized by cancer cells to degrade their MHC-I and to lower their vulnerability to TNF-α and CTLs. Lysosomal pH-sensitive polymeric nanoparticle as a drug delivery carrier may also be a novel autophagy inhibitor to boost immunotherapy, but such an important effect has not been investigated. Herein, we developed a unique tumor acidity-activatable macromolecular nanodrug (called P-PDL1-CP) with the poly(2-diisopropylaminoethyl methacrylate) (PDPA) core and the conjugations of both aPD-L1 and long-chain polyethylene glycol (PEG) coating. The PDPA core was demonstrated to disturb lysosome to block the autophagic flux, thus elevating the cancer cell's MHC-I expression and vulnerability to the TNF-α and CTLs. Long-chain PEG facilitated a good tumor accumulation of P-PDL1-CP nanodrug. Furthermore, P-PDL1-CP nanodrug inhibited tumor autophagy, which synergized with aPD-L1 to promote the tumor-infiltrating CTLs and DCs maturation, to elevate intratumoral TNF-α and IFN-γ levels, and to elicit an anti-tumor immune memory effect in mice for PCa growth inhibition with low side effects. This study verified the synergistic anti-PCa treatment between autophagy inhibition and PD-L1 blockade and meantime broadened the application of pH-sensitive macromolecular nanodrug. STATEMENT OF SIGNIFICANCE: A macromolecular nanodrug, comprising the PDPA core and the surface conjugation of both aPD-L1 antibodies and long-chain PEG coating via a tumor acidity-labile α-carboxy-dimethylmaleic anhydride amine bond, was developed. Tumoral acidity triggered the release of aPD-L1 for immunotherapy. Meantime, the charge switch of the remanent nanodrug enhanced the cancer cell uptake of PDPA, which disturbed the lysosomes to inhibit autophagy. This advanced nanodrug promoted the tumor-infiltrating CTLs and DCs maturation, elevated the intratumoral TNF-α and IFN-γ levels, and elicited the robust anti-tumor immune memory effect. This study demonstrated that the pH-sensitive PDPA macromolecule could serve as a carrier for the aPD-L1 delivery and as an efficient autophagy inhibitor to boost the immunotherapy of prostate cancer.

Prognostic and Clinical Significance of Human Leukocyte Antigen Class I Expression in Breast Cancer: A Meta-Analysis

BACKGROUND

The value of human leukocyte antigen (HLA; also known as major histocompatibility complex) class I expression for the prediction of breast cancer survival outcomes remains unclear. We conducted a meta-analysis to explore the prognostic significance of this expression.

MATERIALS AND METHODS

We searched electronic databases to identify reports on associations of HLA class I protein or mRNA expression with survival outcomes and clinicopathological factors in the breast cancer context. Pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were used to conduct a quantitative meta-analysis.

RESULTS

The sample comprised eight studies involving 3590 patients. Only the classical HLA class Ia (HLA-ABC) molecules studies were included in this meta-analysis. Elevated HLA class I protein expression was found to be significantly related to better disease-free survival (DFS) (HR 0.58, 95% CI 0.35-0.95, P = 0.03), particularly among patients with triple-negative breast cancer (TNBC) (HR 0.31, 95% CI 0.18-0.52, P < 0.001), but not to overall survival. It was also associated with estrogen receptor (ER) negativity (OR 1.71, 95% CI 1.24-2.35, P = 0.001), progesterone receptor (PR) negativity (OR 1.49, 95% CI 1.22-1.81, P < 0.001), human epidermal growth factor receptor 2 (HER2) positivity (OR 1.51, 95% CI 1.18-1.94, P = 0.001), TNBC (OR 1.68, 95% CI 1.15-2.45, P < 0.01), high Ki-67 indices (OR 2.06, 95% CI 1.62-2.61, P < 0.001), and high nuclear grades (OR 2.67, 95% CI 2.17-3.29, P < 0.001).

CONCLUSION

This meta-analysis demonstrated that enhanced HLA class I protein expression is significantly associated with the better DFS of patients with breast cancer, especially TNBC, as well as with ER and PR negativity, HER2 positivity, TNBC, and high Ki-67 indices and nuclear grades. The immune target HLA class I may serve as a prognostic indicator for breast cancer.

"HLA-C: evolution, epigenetics, and pathological implications in the major histocompatibility complex"

HLA-C, a gene located within the major histocompatibility complex, has emerged as a prominent target in biomedical research due to its involvement in various diseases, including cancer and autoimmune disorders; even though its recent addition to the MHC, the interaction between HLA-C and KIR is crucial for immune responses, particularly in viral infections. This review provides an overview of the structure, origin, function, and pathological implications of HLA-C in the major histocompatibility complex. In the last decade, we systematically reviewed original publications from Pubmed, ScienceDirect, Scopus, and Google Scholar. Our findings reveal that genetic variations in HLA-C can determine susceptibility or resistance to certain diseases. However, the first four exons of HLA-C are particularly susceptible to epigenetic modifications, which can lead to gene silencing and alterations in immune function. These alterations can manifest in diseases such as alopecia areata and psoriasis and can also impact susceptibility to cancer and the effectiveness of cancer treatments. By comprehending the intricate interplay between genetic and epigenetic factors that regulate HLA-C expression, researchers may develop novel strategies for preventing and treating diseases associated with HLA-C dysregulation.

Epigenetic regulation and therapeutic targets in the tumor microenvironment

The tumor microenvironment (TME) is crucial to neoplastic processes, fostering proliferation, angiogenesis and metastasis. Epigenetic regulations, primarily including DNA and RNA methylation, histone modification and non-coding RNA, have been generally recognized as an essential feature of tumor malignancy, exceedingly contributing to the dysregulation of the core gene expression in neoplastic cells, bringing about the evasion of immunosurveillance by influencing the immune cells in TME. Recently, compelling evidence have highlighted that clinical therapeutic approaches based on epigenetic machinery modulate carcinogenesis through targeting TME components, including normalizing cells' phenotype, suppressing cells' neovascularization and repressing the immunosuppressive components in TME. Therefore, TME components have been nominated as a promising target for epigenetic drugs in clinical cancer management. This review focuses on the mechanisms of epigenetic modifications occurring to the pivotal TME components including the stroma, immune and myeloid cells in various tumors reported in the last five years, concludes the tight correlation between TME reprogramming and tumor progression and immunosuppression, summarizes the current advances in cancer clinical treatments and potential therapeutic targets with reference to epigenetic drugs. Finally, we summarize some of the restrictions in the field of cancer research at the moment, further discuss several interesting epigenetic gene targets with potential strategies to boost antitumor immunity.

Immune checkpoint therapy-current perspectives and future directions

Immune checkpoint therapy (ICT) has dramatically altered clinical outcomes for cancer patients and conferred durable clinical benefits, including cure in a subset of patients. Varying response rates across tumor types and the need for predictive biomarkers to optimize patient selection to maximize efficacy and minimize toxicities prompted efforts to unravel immune and non-immune factors regulating the responses to ICT. This review highlights the biology of anti-tumor immunity underlying response and resistance to ICT, discusses efforts to address the current challenges with ICT, and outlines strategies to guide the development of subsequent clinical trials and combinatorial efforts with ICT.

Epigenetics regulation of prostate cancer: Biomarker and therapeutic potential

Prostate cancer (CaP) is the second leading cause of cancer death and displays a broad range of clinical behavior from relatively indolent to aggressive metastatic disease. The etiology of most cases of CaP is not understood completely, which makes it imperative to search for the molecular basis of CaP and markers for early diagnosis. Epigenetic modifications, including changes in DNA methylation patterns, histone modifications, miRNAs, and lncRNAs are key drivers of prostate tumorigenesis. These epigenetic defects might be due to deregulated expression of the epigenetic machinery, affecting the expression of several important genes like GSTP1, RASSF1, CDKN2, RARRES1, IGFBP3, RARB, TMPRSS2-ERG, ITGB4, AOX1, HHEX, WT1, HSPE, PLAU, FOXA1, ASC, GPX3, EZH2, LSD1, etc. In this review, we highlighted the most important epigenetic gene alterations and their variations as a diagnostic marker and target for therapeutic intervention of CaP in the future. Characterization of epigenetic changes involved in CaP is obscure and adequate validation studies are still required to corroborate the present results that would be the impending future of transforming basic research settings into clinical practice.