Enhancing HCC Treatment: innovatively combining HDAC2 inhibitor with PD-1/PD-L1 inhibition

UBE4B modulates BET inhibitor sensitivity via KLHL22-JAK2-PIM1 axis in hepatocellular carcinoma

Ubiquitination factor E4B (UBE4B) is crucial to the high mortality rate and poor prognosis associated with hepatocellular carcinoma (HCC). Evidence suggests that aberrant epigenetic modifications significantly contribute to HCC carcinogenesis, making epigenetic mechanisms a promising area for therapeutic intervention. However, the precise role of UBE4B in the epigenetic dysregulation observed in HCC remains elusive. In this study, we silenced UBE4B in HCC cells and exposed them to a panel of epigenetic compounds. Notably, only bromodomain and extraterminal inhibitors (BETis) exhibited resistance to UBE4B silencing, while restoring UBE4B expression partially reversed this resistance. Furthermore, UBE4B deletion led to decreased growth rates and impaired proliferation, resulting in cell cycle arrest and diminished tumorigenicity. However, this deletion did not affect the cell cycle arrest induced by BETi. Interestingly, KLHL22, a ubiquitin substrate of UBE4B, accumulated in UBE4B-deleted cells. Knockdown of KLHL22 restored sensitivity to BETi, accompanied by downregulation of JAK2 and upregulation of its negative regulator, LNK. Additionally, UBE4B deletion resulted in decreased LNK expression, and LNK knockdown increased JAK2 expression and mediated resistance to BETi. Increased JAK2 subsequently targeted PIM1, further reducing the inhibitory effect of BETi. Directly silencing PIM1 in UBE4B-deleted cells restored BETi sensitivity. Overall, our findings provide novel insights into the relationship between UBE4B expression and BETi sensitivity, which is mediated through the KLHL22-JAK2-PIM1 regulatory axis. These findings not only deepen our understanding of the mechanisms underlying HCC progression but also suggest that targeting this axis may present a promising therapeutic strategy for enhancing the treatment outcomes of HCC.

Epigenetic regulators combined with tumour immunotherapy: current status and perspectives

Immunotherapy, particularly immune checkpoint inhibitor therapy, has demonstrated clinical benefits in solid tumours. Despite its satisfactory clinical efficacy, it still faces several issues, such as limited eligibility, low response rates and cytotoxicity. Cancer epigenetics implies that tumour cells exhibit unique phenotypes because of their unique characteristics, thus reprogramming of the epigenome holds promise for cancer therapy. Epigenetic regulation plays an important role in regulating gene expression during tumour development and maintenance. Epigenetic regulators induce cancer cell cycle arrest, apoptosis and differentiation of cancer cells, thereby exerting anti-tumour effects. Recent studies have revealed a significant correlation between epigenetic regulatory factors and immune checkpoint therapy. Epigenetics can modulate various aspects of the tumour immune microenvironment and immune response to enhance the sensitivity of immunotherapy, such as lowering the concentration required and mitigating cytotoxicity. This review primarily discusses DNA methyltransferase inhibitors, histone deacetylase inhibitors, enhancer of zeste homolog 2 inhibitors and lysine-specific demethylase 1 inhibitors, which are associated with transcriptional repression. This repression alters the expression of genes involved in the immune checkpoint, thereby enhancing the effectiveness of immunotherapy. We also discuss the potential and challenges of tumour immunotherapy and highlight its advantages, application challenges and clinical research on integrating epigenetic regulatory factors with tumour immunotherapy.

A novel phosphodiesterase target as a therapeutic approach: inhibiting DEN-induced hepatocellular carcinoma progression

Hepatocellular Carcinoma (HCC) is one of the most common and fatal types of liver cancer worldwide; in this sense, Diethylnitrosamine (DEN) has been established as a potent carcinogen affecting the development and progression of this disease. The present work focused on determining whether phosphodiesterase (PDE) enzymes, especially PDE5, may serve as targets in the therapeutic treatment of DEN-induced HCC. PDE5 inhibitors, widely used as therapeutic drugs for cardiovascular diseases and erectile dysfunction, have recently been found to be promising in preclinical cancer models through the modulation of key signaling pathways implicated in the progression of tumors, such as the cGMP-PKG, JNK, and MAPK pathways. These pathways are very important for cell proliferation, apoptosis and metastasis, and their dysregulation contributes to the aggressive nature of HCC. This study assessed the potential of PDE5 inhibitors to suppress proliferation, induce apoptosis, and alter the tumor microenvironment, thus potentially improving standard chemotherapy and immunotherapy interventions. By inhibiting certain PDE isoforms with these drugs, an anticancer response might occur as part of a complex mechanism that acts on both cancer cells and the microenvironment favorable for tumor growth. A preliminary review indicated that PDE inhibitors may be a promising therapeutic approach for overcoming some of the shortcomings of current treatments, particularly the development of resistance and the toxic effects of these treatments. Additional clinical investigations are necessary to determine the safety profile, appropriate amount of Osage, and long-term efficacy of these agents in the treatment of HCC, particularly in DEN-induced animal models. This study contributes to the expanding body of evidence supporting the use of PDE inhibitors in cancer treatment.

The role of HDAC2 inhibition in cardioprotection against doxorubicin-induced myocardial injury

Introduction

The molecular mechanisms underlying cardioprotection against doxorubicin (DOX)-induced myocardial injury are poorly understood. Histone deacetylase 2 (HDAC2) plays a significant role in oxidative stress, apoptosis, and mitochondrial dysfunction and is implicated in many human diseases, This study investigated the relationship between HDAC2 expression and DOX-induced myocardial injury using the in vivo rat model of DOX-induced cardiotoxicity and in vitro experiments with the H9c2 cardiomyocytes.

Methods

The rat model of DOX-induced myocardial injury was established by administering DOX via intraperitoneal injections. HDAC2 expression was suppressed by administering rats with sodium butyrate (SB) via intraperitoneal injections. Echocardiography measurements were performed at baseline and on day 15 post-treatment. The rats were euthanized on day 15 and cardiac tissues were harvested. The cardiac tissue samples were analyzed by hematoxylin and eosin H&E staining, immunohistochemistry, Masson staining, Sirius Red staining, TUNEL staining, and western blotting to determine the status of HDAC2 expression and myocardial apoptosis. In the vitro experiments, H9c2 cells were treated with DOX. HDAC2 expression was suppressed using sodium butyrate or transfected cells with the shRNA knockdown HDAC2 (shHDAC2). The H9c2 cells from different groups were analyzed by Rt-qPCR, CCK-8 cell viability assay, and western blotting to determine the status of HDAC2 expression and cardiomyocyte apoptosis.

Results

DOX treatment induced cardiac dysfunction in rats. The cardiac tissues of the DOX-treated rats and H9c2 cells showed significantly higher levels of HDAC2 compared to the corresponding controls. However, inhibition of HDAC2 significantly mitigated DOX-induced myocardial injury in rats. This suggested a strong association between HDAC2 expression and DOX-induced myocardial injury. In the H9c2 cells, HDAC2 knockdown by shHDAC2 alleviated DOX-induced apoptosis by enhacing AKT phosphorylation. These findings demonstrated that HDAC2 silencing protected against DOX-induced cardiomyocyte apoptosis by activating the PI3K/AKT signaling pathway.

Conclusion

Suppressing HDAC2 protected against DOX-induced cardiomyocyte apoptosis by activating the PI3K/AKT signaling pathway. Therefore, HDAC2 is a promising therapeutic target for mitigating DOX-induced myocardial injury.

Bidirectional regulation of the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon gene pathway and its impact on hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) ranks as the fourth leading cause of cancer-related deaths in China, and the treatment options are limited. The cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) activates the stimulator of interferon gene (STING) signaling pathway as a crucial immune response pathway in the cytoplasm, which detects cytoplasmic DNA to regulate innate and adaptive immune responses. As a potential therapeutic target, cGAS-STING pathway markedly inhibits tumor cell proliferation and metastasis, with its activation being particularly relevant in HCC. However, prolonged pathway activation may lead to an immunosuppressive tumor microenvironment, which fostering the invasion or metastasis of liver tumor cells.

AIM

To investigate the dual-regulation mechanism of cGAS-STING in HCC.

METHODS

This review was conducted according to the PRISMA guidelines. The study conducted a comprehensive search for articles related to HCC on PubMed and Web of Science databases. Through rigorous screening and meticulous analysis of the retrieved literature, the research aimed to summarize and elucidate the impact of the cGAS-STING pathway on HCC tumors.

RESULTS

All authors collaboratively selected studies for inclusion, extracted data, and the initial search of online databases yielded 1445 studies. After removing duplicates, the remaining 964 records were screened. Ultimately, 55 articles met the inclusion criteria and were included in this review.

CONCLUSION

Acute inflammation can have a few inhibitory effects on cancer, while chronic inflammation generally promotes its progression. Extended cGAS-STING pathway activation will result in a suppressive tumor microenvironment.

Novel dual-targeting inhibitors of NSD2 and HDAC2 for the treatment of liver cancer: structure-based virtual screening, molecular dynamics simulation, and in vitro and in vivo biological activity evaluations

Liver cancer exhibits a high degree of heterogeneity and involves intricate mechanisms. Recent research has revealed the significant role of histone lysine methylation and acetylation in the epigenetic regulation of liver cancer development. In this study, five inhibitors capable of targeting both histone lysine methyltransferase nuclear receptor-binding SET domain 2 (NSD2) and histone deacetylase 2 (HDAC2) were identified using a structure-based virtual screening approach. Notably, DT-NH-1 displayed a potent inhibition of NSD2 (IC50 = 0.08 ± 0.03 μM) and HDAC2 (IC50 = 5.24 ± 0.87 nM). DT-NH-1 also demonstrated a strong anti-proliferative activity against various liver cancer cell lines, particularly HepG2 cells, and exhibited a high level of biological safety. In an experimental xenograft model involving HepG2 cells, DT-NH-1 showed a significant reduction in tumour growth. Consequently, these findings indicate that DT-NH-1 will be a promising lead compound for the treatment of liver cancer with epigenetic dual-target inhibitors.

Discovery of a Novel and Potent Dual-Targeting Inhibitor of ATM and HDAC2 Through Structure-Based Virtual Screening for the Treatment of Testicular Cancer

Purpose

Dual inhibition of ataxia telangiectasia mutated (ATM) and histone deacetylase 2 (HDAC2) may be a potential strategy to improve antitumor efficacy in testicular cancer.

Methods

A combined virtual screening protocol including pharmacophore modeling and molecular docking was used for screening potent dual-target ATM/HDAC2 inhibitors. In order to obtain the optimal lead compound, the dual ATM/HDAC2 inhibitory activity of the screened compounds was further evaluated using enzyme inhibition methods. The binding stability of the optimal compound to the dual targets was verified by molecular dynamics (MD) simulation. MTT assay and in vivo antitumor experiment were performed to validate antitumor efficacy of the optimal compound in testicular cancer.

Results

Here, we successfully discovered six potent dual-target ATM/HDAC2 inhibitors (AMHs 1-6), which exhibited good inhibitory activity against both ATM and HDAC2. Among them, AMH-4 showed strong inhibitory activity against both ATM (IC50 = 1.12 ± 0.03 nM) and HDAC2 (IC50 = 3.04 ± 0.08 nM). MD simulation indicated that AMH-4 binds to ATM and HDAC2 with satisfactory stability. Importantly, AMH-4 had significant antiproliferative activity on human testicular tumor cells, especially NTERA-2 cL.D1 cells, and no inhibitory effect on normal human testicular cells. In vivo experiments exhibited that AMH-4 was more effective than lartesertib and vorinostat in inhibiting the growth of NTERA-2 cL.D1 xenograft tumors with low toxicity.

Conclusion

Overall, these results suggest that AMH-4 is an effective and low toxicity candidate for the treatment of testicular germ cell tumors.

HDAC2 promotes autophagy-associated HCC malignant progression by transcriptionally activating LAPTM4B

Hepatocellular carcinoma (HCC) is a significant global health challenge. The activation of autophagy plays an essential role in promoting the proliferation and survival of cancer cells. However, the upstream regulatory network and mechanisms governing autophagy in HCC remain unclear. This study demonstrated that histone deacetylase 2 (HDAC2) regulates autophagy in HCC. Its expression was elevated in HCC tissues, and high HDAC2 expression was strongly associated with poor prognosis in individuals with HCC. Integrated in vitro and in vivo investigations confirmed that HDAC2 promotes autophagy and autophagy-related malignant progression in HCC. Mechanistically, HDAC2 bound specifically to the lysosome-associated protein transmembrane 4-β (LAPTM4B) promoter at four distinct binding sites, enhancing its transcriptional activation and driving autophagy-related malignant progression in HCC. These findings establish LAPTM4B as a direct target gene of HDAC2. Furthermore, the selective inhibitor of HDAC2 effectively alleviated the malignant development of HCC. In addition, multivariate Cox regression analysis of 105 human HCC samples revealed that HDAC2 expression is an independent predictor of HCC prognosis. This study underscores the crucial role of the HDAC2-LAPTM4B axis in regulating autophagy in the malignant evolution of HCC and highlights the potential of targeting HDAC2 to prevent and halt the malignant progression of HCC.

Discovery of a dual-target DYRK2 and HDAC8 inhibitor for the treatment of hepatocellular carcinoma

Dual-specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2) and histone deacetylase 8 (HDAC8) have been shown to be associated with the development of several cancers. Here, we identified a dual-target DYRK2/HDAC8 inhibitor (DYC-1) through a combined virtual screening protocol. DYC-1 exhibited nanomolar inhibitory activity against both DYRK2 (IC50 = 5.27 ± 0.13 nM) and HDAC8 (IC50 = 8.06 ± 0.47 nM). Molecular dynamics simulations showed that DYC-1 had positive binding stability with DYRK2 and HDAC8. Importantly, the cytotoxicity assay indicated that DYC-1 exhibited superior antiproliferative activity against human liver cancer, especially SK-HEP-1 cells, and had no significant inhibition on normal liver cells. Moreover, DYC-1 showed a strong inhibitory effect on the growth of SK-HEP-1 xenograft tumors with no significant side effects. These data suggest that DYC-1 is a high-efficacy and low-toxic antitumor agent for the treatment of hepatocellular carcinoma.

The Epigenetic Modifiers HDAC2 and HDAC7 Inversely Associate with Cancer Stemness and Immunity in Solid Tumors

Dysregulation of histone deacetylases (HDACs) is closely associated with cancer development and progression. Here, we comprehensively analyzed the association between all HDAC family members and several clinicopathological and molecular traits of solid tumors across 22 distinct tumor types, focusing primarily on cancer stemness and immunity. To this end, we used publicly available TCGA data and several bioinformatic tools (i.e., GEPIA2, TISIDB, GSCA, Enrichr, GSEA). Our analyses revealed that class I and class II HDAC proteins are associated with distinct cancer phenotypes. The transcriptomic profiling indicated that class I HDAC members, including HDAC2, are positively associated with cancer stemness, while class IIA HDAC proteins, represented by HDAC7, show a negative correlation to cancer stem cell-like phenotypes in solid tumors. In contrast to tumors with high amounts of HDAC7 proteins, the transcriptome signatures of HDAC2-overexpressing cancers are significantly enriched with biological terms previously determined as stemness-associated genes. Moreover, high HDAC2-expressing tumors are depleted with immune-related processes, and HDAC2 expression correlates with tumor immunosuppressive microenvironments. On the contrary, HDAC7 upregulation is significantly associated with enhanced immune responses, followed by enriched infiltration of CD4+ and CD8+ T cells. This is the first comprehensive report demonstrating robust and versatile associations between specific HDAC family members, cancer dedifferentiation, and anti-tumor immune statuses in solid tumors.

Cross talk between genetics and biochemistry in the pathogenesis of hepatocellular carcinoma

The liver is a crucial organ in the regulation of metabolism, signaling, and homeostasis. Using recent advanced sequencing technologies, several mutations of genes in major metabolic and signaling pathways have been discovered in the pathogenesis of hepatocellular carcinoma (HCC). These gene signatures alter expression and ultimately affect biochemical pathways by modifying enzyme/protein levels, resulting in numerous clinical outcomes related to HCC. It comes with varying forms of genetic and biochemical alterations, associated with carbohydrate, lipid, nucleic acid, and amino acid metabolism, as well as signaling pathways linked to tumorigenesis. Here, we aim to summarize the main components and mechanisms involved in the progression of HCC with a special focus on the metabolic regulation of key effectors of tumorigenesis, through the crosstalk between genetics and biochemistry. This paper provides an overview of hepatocellular carcinoma, underlying the fundamental effect of gene variations on metabolic and signaling pathways. Since there is still an unmet need for biomarkers and novel therapeutic targets, some of these signature genes or proteins can be used as novel biomarkers for diagnosis, prognosis, and novel potential therapeutic targets for the treatment of HCC.

The extract of an herbal medicine Chebulae fructus inhibits hepatocellular carcinoma by suppressing the Apelin/APJ system

Introduction: Hepatocellular carcinoma (HCC) has been a highly common and pathological disease worldwide, while current therapeutic regimens have limitations. Chebulae Fructus, a common herbal medicine in Asia, has been documented to exert potential therapeutic effects on HCC in ancient medicine clinical practice. However, the molecular mechanism underlying its inhibitory effects on HCC requires further investigation. Methods: In this study, the anti-HCC effect of the aqueous extract of Chebulae Fructus (CFE) on human HCC and its underlying mechanism were evaluated. Assays including CCK8, EdU staining, crystal violet staining, cell clone formation, flow cytometry, wound healing, and transwell were used in vitro. The cell-derived xenograft (CDX) and patient-derived xenograft (PDX) models were used in vivo. Transcriptomics analysis, qRT-PCR, ELISA, IHC staining, and Western blotting were employed to determine the mechanism of action of CFE. Results: The results demonstrate that CFE effectively suppressed the proliferation and activity of HepG2 and PLC/PRF/5 HCC cells. CFE also induced apoptosis, and suppressed the migration and invasion abilities of these cells. Furthermore, CFE exhibited inhibitory effects on tumor growth in both H22 and PLC/PRF/5 mouse models, as well as in an HCC PDX model which is derived from patient tumor samples. Moreover, it was identified that CFE treatment specifically suppressed the Apelin/APJ system in HCC cells and tumor tissues. To investigate the role of the Apelin/APJ system in mediating the effects of CFE treatment, an APJ overexpressed cell model is established. Interestingly, it was found that the overexpression of APJ significantly diminished the inhibitory effects of CFE on HCC in vitro. Discussion: Collectively, this study provides compelling evidence that CFE exerts significant anti-HCC effects in cell and animal models. Moreover, our findings suggest that the Apelin/APJ system may play a vital role in the therapeutic effects of CFE against HCC.

Synergistic Immunoregulation: harnessing CircRNAs and PiRNAs to Amplify PD-1/PD-L1 Inhibition Therapy

The utilization of PD-1/PD-L1 inhibitors marks a significant advancement in cancer therapy. However, the efficacy of monotherapy is still disappointing in a substantial subset of patients, necessitating the exploration of combinational strategies. Emerging from the promising results of the KEYNOTE-942 trial, RNA-based therapies, particularly circRNAs and piRNAs, have distinguished themselves as innovative sensitizers to immune checkpoint inhibitors (ICIs). These non-coding RNAs, notable for their stability and specificity, were once underrecognized but are now known for their crucial roles in regulating PD-L1 expression and bolstering anti-cancer immunity. Our manuscript offers a comprehensive analysis of selected circRNAs and piRNAs, elucidating their immunomodulatory effects and mechanisms, thus underscoring their potential as ICIs enhancers. In conjunction with the recent Nobel Prize-awarded advancements in mRNA vaccine technology, our review highlights the transformative implications of these findings for cancer treatment. We also discuss the prospects of circRNAs and piRNAs in future therapeutic applications and research. This study pioneers the synergistic application of circRNAs and piRNAs as novel sensitizers to augment PD-1/PD-L1 inhibition therapy, demonstrating their unique roles in regulating PD-L1 expression and modulating immune responses. Our findings offer a groundbreaking approach for enhancing the efficacy of cancer immunotherapy, opening new avenues for treatment strategies. This abstract aims to encapsulate the essence of our research and the burgeoning role of these non-coding RNAs in enhancing PD-1/PD-L1 inhibition therapy, encouraging further investigation into this promising field.

Nanoparticle-Mediated Synergistic Chemoimmunotherapy for Cancer Treatment

Until now, there has been a lack of effective strategies for cancer treatment. Immunotherapy has high potential in treating several cancers but its efficacy is limited as a monotherapy. Chemoimmunotherapy (CIT) holds promise to be widely used in cancer treatment. Therefore, identifying their involvement and potential synergy in CIT approaches is decisive. Nano-based drug delivery systems (NDDSs) are ideal delivery systems because they can simultaneously target immune cells and cancer cells, promoting drug accumulation, and reducing the toxicity of the drug. In this review, we first introduce five current immunotherapies, including immune checkpoint blocking (ICB), adoptive cell transfer therapy (ACT), cancer vaccines, oncolytic virus therapy (OVT) and cytokine therapy. Subsequently, the immunomodulatory effects of chemotherapy by inducing immunogenic cell death (ICD), promoting tumor killer cell infiltration, down-regulating immunosuppressive cells, and inhibiting immune checkpoints have been described. Finally, the NDDSs-mediated collaborative drug delivery systems have been introduced in detail, and the development of NDDSs-mediated CIT nanoparticles has been prospected.

PD-L1 Expression in Neoplastic and Immune Cells of Thymic Epithelial Tumors: Correlations with Disease Characteristics and HDAC Expression

BACKGROUND

Programmed death-ligand 1 (PD-L1) expression in neoplastic and immune cells of the tumor microenvironment determines the efficacy of antitumor immunity, while it can be regulated at the epigenetic level by various factors, including HDACs. In this study, we aim to evaluate the expression patterns of PD-L1 in thymic epithelial tumors (TETs), while we attempt the first correlation analysis between PD-L1 and histone deacetylases (HDACs) expression.

METHODS

Immunohistochemistry was used to evaluate the expression of PD-L1 in tumor and immune cells of 91 TETs with SP263 and SP142 antibody clones, as well as the expressions of HDCA1, -2, -3, -4, -5, and -6.

RESULTS

The PD-L1 tumor proportion score (TPS) was higher, while the immune cell score (IC-score) was lower in the more aggressive TET subtypes and in more advanced Masaoka-Koga stages. A positive correlation between PD-L1 and HDAC-3, -4, and -5 cytoplasmic expression was identified.

CONCLUSIONS

Higher PD-L1 expression in neoplastic cells and lower PD-L1 expression in immune cells of TETs characterizes more aggressive and advanced neoplasms. Correlations between PD-L1 and HDAC expression unravel the impact of epigenetic regulation on the expression of immune checkpoint molecules in TETs, with possible future applications in combined therapeutic targeting.