Receptor-Interacting Protein Kinase 3 Deficiency Recruits Myeloid-Derived Suppressor Cells to Hepatocellular Carcinoma Through the Chemokine (C-X-C Motif) Ligand 1-Chemokine (C-X-C Motif) Receptor 2 Axis

The important role of myeloid-derived suppressor cells: From hepatitis to liver cancer

Liver homeostasis is coordinated by crosstalk between resident and infiltrating inflammatory cells. Liver disease creates a dynamic inflammatory microenvironment characterized by aberrant metabolism and continuous hepatic regeneration, making it an important risk factor for hepatocellular carcinoma (HCC) as well as liver failure. Recent studies have revealed a critical heterogeneous population of myeloid-derived suppressor cells (MDSCs), which influence liver disease progression and malignancy by dynamically regulating the immune microenvironment. MDSCs play an important role in preventing excessive immune responses in the liver. However, MDSCs are also associated with the promotion of liver injury and liver cancer progression. The plasticity of MDSCs in liver disease is a unique challenge for therapeutic intervention strategies and requires a deeper understanding of the underlying mechanisms. Here, we review the role of MDSCs in the establishment and progression of liver disease and highlight the evidence for MDSCs as a priority target for current and future therapeutic strategies. We explore the fate of MDSCs from hepatitis to liver cancer, providing recent insights into potential targets for clinical intervention.

The immunosuppressive role of MDSCs in HCC: mechanisms and therapeutic opportunities

Hepatocellular carcinoma (HCC) is a prevalent malignancy with a significant global burden. Despite substantial advancements in HCC treatment in recent years, therapeutic efficacy remains constrained by immune evasion mechanisms within the tumor microenvironment (TME). Myeloid-derived suppressor cells (MDSCs), as critical immunosuppressive elements of the TME, have garnered increasing attention for their role in tumor progression. Recent studies emphasize their central involvement in promoting immune evasion, tolerance, and immunosuppression in HCC. This review examines the contributions of MDSCs to HCC pathogenesis, elucidates their underlying mechanisms, and discusses ongoing clinical trials, emphasizing their potential as therapeutic targets for improving clinical outcomes.

Engineering nanozyme immunomodulator with magnetic targeting effect for cascade-enzyodynamic and ultrasound-reinforced metallo-immunotherapy in prostate carcinoma

Conventional immunotherapy exhibits low response rates due to the immunosuppressive tumor microenvironment (TME). To overcome this limitation, this study introduces ZFPG nanoparticles (ZFPG NPs) with ZnFe2O4@Pt cores and glucose oxidase (GOx) shells. The ZFPG NPs possess five-enzyme activities, good sonosensitivity, and remarkable magnetic targeting properties, which facilitate sono-metallo-immunotherapy for prostate cancer treatment in male mice. Specifically, the magnetic targeting ability effectively improves their accumulation in tumors while still showing enrichment in the liver and kidneys. The multienzyme cascade catalysis and sonosensitivity of these NPs effectively deplete glutathione and glucose, and enhance the generation and utilization of H2O2, thereby inducing multiple ROS bursts. Furthermore, these comprehensive effects up-regulate the HMOX1 to promote the Fe2+ and lipid peroxides accumulation, thereby inducing immunogenic ferroptosis. This strategy facilitates anti-tumor immunity by ameliorating the immunosuppressive TME and inhibiting lung metastatic progression. This joint warfare strategy offers a powerful solution to address conventional immunotherapy limitations.

HDAC1-3 inhibition triggers NEDD4-mediated CCR2 downregulation and attenuates immunosuppression in myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) play a critical role in cancer progression and resistance, thus representing promising targets for immunotherapy. Despite the established role of histone deacetylases (HDACs) in epigenetic regulation of cell fate and function, their specific impact on MDSCs remains elusive. We sought to investigate the effects and underlying mechanisms of HDAC on MDSCs using various HDAC inhibitors. Our results indicate that HDAC1-3 inhibitors reduce CCR2 expression, a chemokine receptor that mediates the migration of monocytic (M-)MDSCs to tumors and attenuated the immunosuppressive activity of MDSCs. In an orthotropic hepatocellular carcinoma (HCC) murine model, HDAC1-3 inhibitors reduced the infiltration of M-MDSCs, increased the number of natural killer cells in tumors, and suppressed tumor growth. Our results also suggest that HDAC1-3 inhibitors potentiate the antitumor effects of anti-programmed cell death protein 1 antibodies. ATAC-seq and RNA-seq analyses revealed 115 genes epigenetically upregulated by HDAC1-3 inhibitors, primarily linked to transcriptional regulation and ubiquitination. We further elucidated that HDAC1-3 inhibitors facilitate CCR2 protein degradation through ubiquitination-mediated by NEDD4 E3 ligase. Our findings reveal a novel mechanism of action of HDAC1-3 inhibitors in MDSCs and suggest a potential synergistic immunotherapy strategy for clinical benefit in HCC.

DDX17-Mediated Upregulation of CXCL8 Promotes Hepatocellular Carcinoma Progression via Co-activating β-catenin/NF-κB Complex

Hepatocellular carcinoma (HCC) is a well-known inflammation-related cancer, that accounts for fifth most prevalent neoplasm and the third major driver of cancer associated fatality globally. Accumulating evidence has elucidated that C-X-C motif chemokine ligands (CXCLs) are aberrantly upregulated in HCC and are involved in inflammation-induced hepatocarcinogenesis and metastasis. Herein, we identified a novel function of DEAD-box RNA helicase 17 (DDX17) as an oncogenic factor via transactivating CXCL8 in HCC. Unlike the adjacent nontumor tissues, DDX17 was highly expressed in tumor tissues compared in two independent cohorts and that it acts as an independent prognostic indicator for patients who have HCC. Mechanistically, DDX17 interacts with β-catenin and NF-κB, and promotes their nuclear translocation to promote the transcription of the inflammatory gene CXCL8, thus promoting HCC proliferation and invasion in vitro and in vivo. More interestingly, stimulation with recombinant human CXCL8 augmented the interaction of NF-κB with DDX17/β-catenin and enhanced its autocrine activation by promoting the phosphorylation of IκBα. Furthermore, blocking the association of the DDX17/β-catenin/NF-κB complex with a CXCR1/2 inhibitor markedly abrogated DDX17-mediated HCC proliferation and metastasis. Overall, this study provided new insights into DDX17-mediated pro-inflammatory chemokine activation, which unveiled the association between DDX17 and β-catenin/ NF-κB complex in transactivating the expression of CXCL8. The usage of CXCR1/2 inhibitor to block DDX17-induced CXCL8 signaling activation might be a potential therapeutic approach for HCC treatment.

Bioinformatics and experimental verification to explore the potential mechanism of ginsenoside Rg3 suppresses hepatocellular carcinoma progression

Ginsenoside Rg3 is an extract from ginseng and has the activities of antitumor in a variety of carcinomas, making it a promising monomer of Chinese herbal medicine for tumor treatment. This study aimed to investigate the targets and mechanisms of action of Rg3 in hepatocellular carcinoma (HCC). The molecular structure of Rg3 was obtained, and 100 potential targets were identified using the SwissTargetPrediction database. Univariate Cox regression analysis on the TCGA-LIHC cohort identified 25 genes as candidate targets of Rg3 with significant prognostic relevance. Consensus clustering divided the TCGA-LIHC cohort into two subtypes: C1 and C2. The C2 subtype exhibited worse overall survival, and significant differences in the expression patterns of the 25 candidate genes were observed between the subtypes. Clinical characteristics also differed significantly between the C1 and C2 subtypes. Mutation analysis showed a higher mutation rate and specific gene mutations in the C2 subtype. Increased immune cell infiltration, including macrophages, Th1 cells, and Th17 cells, was observed in the C2 subtype. Here, an orthotopic murine HCC model was established using Hepa1-6 (murine liver carcinoma cells) in immunocompetent C57BL/6 mice. Rg3 was administered via intraperitoneal injection. Tumor volumes were measured using calipers, and the volume was calculated using the formula: width^2 × length × 0.5. This method, while traditional, has been validated and provides consistent and reliable data for assessing tumor progression and treatment efficacy. The function of Rg3on tumor growth and angiogenesis was evaluated in vitro and in vivo. Especially the role of Rg3 in regulating the myeloid-derived suppressor cells (MDSCs) recruitment and Kupffer cells function were investigated. In the present study we found that Rg3 administration suppressed tumor growth and angiogenesis in vivo. In the liver tissues of HCC-bearing mice, Kupffer cells expressed more co-inhibitory molecule CD274 and less co-stimulatory molecules CD86 and MHCII, whereas Rg3 treatment induced the restoration of Kupffer cells function. Rg3 also increased the efficiency of Kupffer cells as antigen-presenting cells. Furthermore, an increased MDSCs proportion in tumor tissues and surrounding parenchyma was detected in HCC-bearing livers, and this enhancement was blocked after Rg3 administration. In vitro, co-culture of Kupffer cells with MDSCs resulted in decreased CD86 expression and increased CD274 expression in Kupffer cells. Kupffer cells also produced decreased IL-6 and IL-18 level and upregulated IL-10 level after co-culture with MDSCs. This study provides insights into the potential targets and mechanisms of Rg3 in HCC and lays a foundation for personalized treatment strategies.

Activation of NOD1 on tumor-associated macrophages augments CD8+ T cell-mediated antitumor immunity in hepatocellular carcinoma

The efficacy of immunotherapy targeting the PD-1/PD-L1 pathway in hepatocellular carcinoma (HCC) is limited. NOD-like receptors (NLRs) comprise a highly evolutionarily conserved family of cytosolic bacterial sensors, yet their impact on antitumor immunity against HCC remains unclear. In this study, we uncovered that NOD1, a well-studied member of NLR family, exhibits predominant expression in tumor-associated macrophages (TAMs) and correlates positively with improved prognosis and responses to anti-PD-1 treatments in patients with HCC. Activation of NOD1 in vivo augments antitumor immunity and enhances the effectiveness of anti-PD-1 therapy. Mechanistically, NOD1 activation resulted in diminished expression of perilipin 5, thereby hindering fatty acid oxidation and inducing free fatty acid accumulation in TAMs. This metabolic alteration promoted membrane localization of the costimulatory molecule OX40L in a lipid modification-dependent manner, thereby activating CD8+ T cells. These findings unveil a previously unrecognized role for NOD1 in fortifying antitumor T cell immunity in HCC, potentially advancing cancer immunotherapy.

New perspectives on chemokines in hepatocellular carcinoma therapy: a critical pathway for natural products regulation of the tumor microenvironment

Hepatocellular carcinoma (HCC) is one of the most common primary neoplasms of the liver and one of the most common solid tumors in the world. Its global incidence is increasing and it has become the third leading cause of cancer-related deaths. There is growing evidence that chemokines play an important role in the tumor microenvironment, regulating the migration and localization of immune cells in tissues and are critical for the function of the immune system. This review comprehensively analyses the expression and activity of chemokines in the TME of HCC and describes their interrelationship with hepatocarcinogenesis and progression. Special attention is given to the role of chemokine-chemokine receptors in the regulation of immune cell accumulation in the TME. Therapeutic strategies targeting tumor-promoting chemokines or the induction/release of beneficial chemokines are reviewed, highlighting the potential value of natural products in modulating chemokines and their receptors in the treatment of HCC. The in-depth discussion in this paper provides a theoretical basis for the treatment of HCC. It is an important reference for new drug development and clinical research.

Immunosuppressive tumor microenvironment in the progression, metastasis, and therapy of hepatocellular carcinoma: from bench to bedside

Hepatocellular carcinoma (HCC) is a highly heterogeneous malignancy with high incidence, recurrence, and metastasis rates. The emergence of immunotherapy has improved the treatment of advanced HCC, but problems such as drug resistance and immune-related adverse events still exist in clinical practice. The immunosuppressive tumor microenvironment (TME) of HCC restricts the efficacy of immunotherapy and is essential for HCC progression and metastasis. Therefore, it is necessary to elucidate the mechanisms behind immunosuppressive TME to develop and apply immunotherapy. This review systematically summarizes the pathogenesis of HCC, the formation of the highly heterogeneous TME, and the mechanisms by which the immunosuppressive TME accelerates HCC progression and metastasis. We also review the status of HCC immunotherapy and further discuss the existing challenges and potential therapeutic strategies targeting immunosuppressive TME. We hope to inspire optimizing and innovating immunotherapeutic strategies by comprehensively understanding the structure and function of immunosuppressive TME in HCC.

Targeting myeloid-derived suppressor cells promotes antiparasitic T-cell immunity and enhances the efficacy of PD-1 blockade (15 words)

Immune exhaustion corresponds to a loss of effector function of T cells that associates with cancer or chronic infection. Here, our objective was to decipher the mechanisms involved in the immune suppression of myeloid-derived suppressor cells (MDSCs) and to explore the potential to target these cells for immunotherapy to enhance checkpoint blockade efficacy in a chronic parasite infection. We demonstrated that programmed cell-death-1 (PD-1) expression was significantly upregulated and associated with T-cell dysfunction in advanced alveolar echinococcosis (AE) patients and in Echinococcus multilocularis-infected mice. PD-1 blockade ex vivo failed to reverse AE patients' peripheral blood T-cell dysfunction. PD-1/PD-L1 blockade or PD-1 deficiency had no significant effects on metacestode in mouse model. This was due to the inhibitory capacities of immunosuppressive granulocytic MDSCs (G-MDSCs), especially in the liver surrounding the parasite pseudotumor. MDSCs suppressed T-cell function in vitro in an indoleamine 2, 3 dioxygenase 1 (IDO1)-dependent manner. Although depleting MDSCs alone restored T-cell effector functions and led to some limitation of disease progression in E. multilocularis-infected mice, combination with PD-1 blockade was better to induce antiparasitic efficacy. Our findings provide preclinical evidence in support of targeting MDSC or combining such an approach with checkpoint blockade in patients with advanced AE. (200 words).

TGF-β1-Induced SOX18 Elevation Promotes Hepatocellular Carcinoma Progression and Metastasis Through Transcriptionally Upregulating PD-L1 and CXCL12

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is characterized by an immune-suppressive microenvironment, which contributes to tumor progression, metastasis, and immunotherapy resistance. Identification of HCC-intrinsic factors regulating the immunosuppressive microenvironment is urgently needed. Here, we aimed to elucidate the role of SYR-Related High-Mobility Group Box 18 (SOX18) in inducing immunosuppression and to validate novel combination strategies for SOX18-mediated HCC progression and metastasis.

METHODS

The role of SOX18 in HCC was investigated in orthotopic allografts and diethylinitrosamine/carbon tetrachloride-induced spontaneous models by using murine cell lines, adeno-associated virus 8, and hepatocyte-specific knockin and knockout mice. The immune cellular composition in the HCC microenvironment was evaluated by flow cytometry and immunofluorescence.

RESULTS

SOX18 overexpression promoted the infiltration of tumor-associated macrophages (TAMs) and regulatory T cells (Tregs) while diminishing cytotoxic T cells to facilitate HCC progression and metastasis in cell-derived allografts and chemically induced HCC models. Mechanistically, transforming growth factor-beta 1 (TGF-β1) upregulated SOX18 expression by activating the Smad2/3 complex. SOX18 transactivated chemokine (C-X-C motif) ligand 12 (CXCL12) and programmed death ligand 1 (PD-L1) to induce the immunosuppressive microenvironment. CXCL12 knockdown significantly attenuated SOX18-induced TAMs and Tregs accumulation and HCC dissemination. Antagonism of chemokine receptor 4 (CXCR4), the cognate receptor of CXCL12, or selective knockout of CXCR4 in TAMs or Tregs likewise abolished SOX18-mediated effects. TGFβR1 inhibitor Vactosertib or CXCR4 inhibitor AMD3100 in combination with anti-PD-L1 dramatically inhibited SOX18-mediated HCC progression and metastasis.

CONCLUSIONS

SOX18 promoted the accumulation of immunosuppressive TAMs and Tregs in the microenvironment by transactivating CXCL12 and PD-L1. CXCR4 inhibitor or TGFβR1 inhibitor in synergy with anti-PD-L1 represented a promising combination strategy to suppress HCC progression and metastasis.

Myeloid-derived suppressor cells in cancer: therapeutic targets to overcome tumor immune evasion

Paradoxically, tumor development and progression can be inhibited and promoted by the immune system. After three stages of immune editing, namely, elimination, homeostasis and escape, tumor cells are no longer restricted by immune surveillance and thus develop into clinical tumors. The mechanisms of immune escape include abnormalities in antitumor-associated immune cells, selection for immune resistance to tumor cells, impaired transport of T cells, and the formation of an immunosuppressive tumor microenvironment. A population of distinct immature myeloid cells, myeloid-derived suppressor cells (MDSCs), mediate immune escape primarily by exerting immunosuppressive effects and participating in the constitution of an immunosuppressive microtumor environment. Clinical trials have found that the levels of MDSCs in the peripheral blood of cancer patients are strongly correlated with tumor stage, metastasis and prognosis. Moreover, animal experiments have confirmed that elimination of MDSCs inhibits tumor growth and metastasis to some extent. Therefore, MDSCs may become the target of immunotherapy for many cancers, and eliminating MDSCs can help improve the response rate to cancer treatment and patient survival. However, a clear definition of MDSCs and the specific mechanism involved in immune escape are lacking. In this paper, we review the role of the MDSCs population in tumor development and the mechanisms involved in immune escape in different tumor contexts. In addition, we discuss the use of these cells as targets for tumor immunotherapy. This review not only contributes to a systematic and comprehensive understanding of the essential role of MDSCs in immune system reactions against tumors but also provides information to guide the development of cancer therapies targeting MDSCs.

Galectin-1 Mediates Chronic STING Activation in Tumors to Promote Metastasis through MDSC Recruitment

The immune system plays a crucial role in the regulation of metastasis. Tumor cells systemically change immune functions to facilitate metastatic progression. Through this study, we deciphered how tumoral galectin-1 (Gal1) expression shapes the systemic immune environment to promote metastasis in head and neck cancer (HNC). In multiple preclinical models of HNC and lung cancer in immunogenic mice, Gal1 fostered the establishment of a premetastatic niche through polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC), which altered the local microenvironment to support metastatic spread. RNA sequencing of MDSCs from premetastatic lungs in these models demonstrated the role of PMN-MDSCs in collagen and extracellular matrix remodeling in the premetastatic compartment. Gal1 promoted MDSC accumulation in the premetastatic niche through the NF-κB signaling axis, triggering enhanced CXCL2-mediated MDSC migration. Mechanistically, Gal1 sustained NF-κB activation in tumor cells by enhancing stimulator of interferon gene (STING) protein stability, leading to prolonged inflammation-driven MDSC expansion. These findings suggest an unexpected protumoral role of STING activation in metastatic progression and establish Gal1 as an endogenous-positive regulator of STING in advanced-stage cancers.

SIGNIFICANCE

Galectin-1 increases STING stability in cancer cells that activates NF-κB signaling and CXCL2 expression to promote MDSC trafficking, which stimulates the generation of a premetastatic niche and facilitates metastatic progression.

Modulation of Myeloid-Derived Suppressor Cells in the Tumor Microenvironment by Natural Products

During carcinogenesis, the microenvironment plays a fundamental role in tumor progression and resistance. This tumor microenvironment (TME) is characterized by being highly immunosuppressive in most cases, which makes it an important target for the development of new therapies. One of the most important groups of cells that orchestrate immunosuppression in TME is myeloid-derived suppressor cells (MDSCs), which have multiple mechanisms to suppress the immune response mediated by T lymphocytes and thus protect the tumor. In this review, we will discuss the importance of modulating MDSCs as a therapeutic target and how the use of natural products, due to their multiple mechanisms of action, can be a key alternative for modulating these cells and thus improve response to therapy in cancer patients.

The Clinical Significance and Role of CXCL1 Chemokine in Gastrointestinal Cancers

One area of cancer research is the interaction between cancer cells and immune cells, in which chemokines play a vital role. Despite this, a comprehensive summary of the involvement of C-X-C motif ligand 1 (CXCL1) chemokine (also known as growth-regulated gene-α (GRO-α), melanoma growth-stimulatory activity (MGSA)) in cancer processes is lacking. To address this gap, this review provides a detailed analysis of CXCL1's role in gastrointestinal cancers, including head and neck cancer, esophageal cancer, gastric cancer, liver cancer (hepatocellular carcinoma (HCC)), cholangiocarcinoma, pancreatic cancer (pancreatic ductal adenocarcinoma), and colorectal cancer (colon cancer and rectal cancer). This paper presents the impact of CXCL1 on various molecular cancer processes, such as cancer cell proliferation, migration, and invasion, lymph node metastasis, angiogenesis, recruitment to the tumor microenvironment, and its effect on immune system cells, such as tumor-associated neutrophils (TAN), regulatory T (T_reg) cells, myeloid-derived suppressor cells (MDSCs), and macrophages. Furthermore, this review discusses the association of CXCL1 with clinical aspects of gastrointestinal cancers, including its correlation with tumor size, cancer grade, tumor-node-metastasis (TNM) stage, and patient prognosis. This paper concludes by exploring CXCL1's potential as a therapeutic target in anticancer therapy.

Periplocin inhibits hepatocellular carcinoma progression and reduces the recruitment of MDSCs through AKT/NF-κB pathway

AIMS

We aimed to evaluate the effect of periplocin on inhibiting hepatocellular carcinoma (HCC) and further determine its mechanisms.

MAIN METHODS

Cytotoxic activity of periplocin against HCC cells was tested by CCK-8 and colony formation assays. The antitumor effects of periplocin were evaluated in human HCC SK-HEP-1 xenograft and murine HCC Hepa 1-6 allograft mouse models. Flow cytometry was used to measure cell cycle distribution, apopotosis, and the number of myeloid-derived suppressor cells (MDSCs). Hoechst 33258 dye was applied to observe the nuclear morphology. Network pharmacology was performed to predict possible signaling pathways. Drug affinity responsive target stability assay (DARTS) was used to evaluate AKT binding of periplocin. Western blotting, immunohistochemistry, and immunofluorescence were used to examine the protein expression levels.

KEY FINDING

Periplocin inhibited cell viability with IC₅₀ values from 50 nM to 300 nM in human HCC cells. Periplocin disrupted cell cycle distribution and promoted cell apoptosis. Moreover, AKT was predicted as the target of periplocin by network pharmacology, which was confirmed by that AKT/NF-κB signaling was inhibited in periplocin-treated HCC cells. Periplocin also inhibited the expression of CXCL1 and CXCL3, leading to decreased accumulation of MDSCs in HCC tumors.

SIGNIFICANCE

These findings reveal the function of periplocin in inhibiting HCC progression by G₂/M arrest, apoptosis and suppression of MDSCs accumulation through blockade of the AKT/NF-κB pathway. Our study further suggests that periplocin has the potential to be developed as an effective therapeutic agent for HCC.

Oxaliplatin-Resistant Hepatocellular Carcinoma Drives Immune Evasion Through PD-L1 Up-Regulation and PMN-Singular Recruitment

BACKGROUND & AIMS

Previously, we showed the inhibitor of differentiation or DNA binding 1 (ID1)/Myc signaling is highly expressed in oxaliplatin-resistant hepatocellular carcinoma (HCC). This study sought to investigate the role of ID1/Myc signaling on immune evasion in oxaliplatin-resistant HCC.

METHODS

The oxaliplatin (OXA)-resistant HCC cell lines (Hepa 1-6-OXA, 97H-OXA, and 3B-OXA) were established and their oxaliplatin tolerance was confirmed in vitro and in vivo. The relationship between ID1/Myc and programmed death-ligand 1 (PD-L1) up-regulation and polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) accumulation was explored. The underlying mechanism in which ID1/Myc signaling regulated PD-L1 expression and PMN-MDSC accumulation was investigated in vitro and vivo.

RESULTS

Increased ID1/Myc expression was identified in oxaliplatin-resistant HCC and correlated with PD-L1 up-regulation and PMN-MDSC accumulation. The knockdown of Myc sensitized oxaliplatin-resistant HCC cells to oxaliplatin and resulted in a decrease of PMN-MDSCs and an increase of interferon-γ⁺ CD8⁺ T cells in a tumor microenvironment. Polymerase chain reaction array, enzyme-linked immunosorbent assay, and MDSC Transwell migration assay indicated that oxaliplatin-resistant HCC cells recruited PMN-MDSCs through chemokine (C-C motif) ligand 5 (CCL5). The dual luciferase reporter assay and chromatin immunoprecipitation assay indicated that Myc could directly increase the transcriptions of PD-L1 and CCL5. Furthermore, anti-PD-L1 antibody combined with CCL5 blockade showed significant antitumor effects in oxaliplatin-resistant HCC.

CONCLUSIONS

ID1/Myc signaling drives immune evasion in oxaliplatin-resistant HCC via PD-L1 up-regulation and PMN-MDSC recruitment. Blocking the ID1/Myc-induced immune tolerance represents a promising treatment target to conquer chemoresistance in HCC.

Biophysical heterogeneity of myeloid-derived microenvironment to regulate resistance to cancer immunotherapy

Despite the advances in immunotherapy for cancer treatment, patients still obtain limited benefits, mostly owing to unrestrained tumour self-expansion and immune evasion that exploits immunoregulatory mechanisms. Traditionally, myeloid cells have a dominantly immunosuppressive role. However, the complicated populations of the myeloid cells and their multilateral interactions with tumour/stromal/lymphoid cells and physical abnormalities in the tumour microenvironment (TME) determine their heterogeneous functions in tumour development and immune response. Tumour-associated myeloid cells (TAMCs) include monocytes, tumour-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), dendritic cells (DCs), and granulocytes. Single-cell profiling revealed heterogeneous TAMCs composition, sub-types, and transcriptomic signatures across 15 human cancer types. We systematically reviewed the biophysical heterogeneity of TAMC composition and pro/anti-tumoral and immuno-suppressive/stimulating properties of myeloid-derived microenvironments. We also summarised comprehensive clinical strategies to overcome resistance to immunotherapy from three dimensions: targeting TAMCs, reversing physical abnormalities, utilising nanomedicines, and finally, put forward futuristic perspectives for scientific and clinical research.

Targeted blocking of CCR2 and CXCR2 improves the efficacy of transarterial chemoembolization of hepatocarcinoma

Background

Transarterial chemoembolization (TACE) has been shown to prolong survival in patients with unresectable hepatocellular carcinoma (HCC); however, the long-term survival remains dismal. Targeting macrophage and neutrophil infiltration is a promising strategy. The CCL2/CCR2 and CXCLs/CXCR2 axes are required for recruitment of macrophages and neutrophils, respectively, in HCC. We investigated the feasibility of CCL2/CCR2 and CXCLs/CXCR2 as therapeutic targets in combination with TACE for treating HCC.

Methods

Expression of CCL2/CCR2 and CXCLs/CXCR2 was analyzed in the primary rat HCC model and one HCC cohort. The relationship between expression levels, neutrophil and macrophage infiltration, hepatocarcinogenesis progression in the rat model, and survival of HCC patients was assessed. The anti-tumor effects of blocking the CCL2/CCR2 and CXCLs/CXCR2 axes by CCR2 and CXCR2 antagonists in combination with TACE were evaluated in HCC rats. The numbers of macrophages, neutrophils, and hepatic progenitor cells were further determined to explore the underlying mechanisms.

Results

High macrophage and neutrophil infiltration and CXCL8 expression were associated with poor prognosis in the TCGA liver cancer dataset. High expression of CCL2/CCR2 and CXCL8/CXCR2 in clinical HCC specimens was associated with reduced survival. Expression of CCL2/CCR2 and CXCL1/CXCR2 was correlated with hepatocarcinogenesis progression in the primary rat HCC model. Blockade of CCL2/CCR2 and CXCLs/CXCR2 enhanced the anti-tumor effect of TACE treatment in this model. Blocking the CCL2/CCR2 and CXCLs/CXCR2 axes with CCR2 and CXCR2 antagonists in TACE-treated rats reduced macrophage and neutrophil infiltration and hepatic progenitor cell activation and thus overcame TACE resistance in HCC.

Conclusions

The results demonstrate the translational potential of immunotherapy targeting the CCL2/CCR2 and CXCLs/CXCR2 axes in combination with TACE therapy for the treatment of HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02771-z.

Overcoming the therapeutic resistance of hepatomas by targeting the tumor microenvironment

Hepatocellular carcinoma (HCC) accounts for the majority of primary liver cancers and is the third leading cause of cancer-related mortality worldwide. Multifactorial drug resistance is regarded as the major cause of treatment failure in HCC. Accumulating evidence shows that the constituents of the tumor microenvironment (TME), including cancer-associated fibroblasts, tumor vasculature, immune cells, physical factors, cytokines, and exosomes may explain the therapeutic resistance mechanisms in HCC. In recent years, anti-angiogenic drugs and immune checkpoint inhibitors have shown satisfactory results in HCC patients. However, due to enhanced communication between the tumor and TME, the effect of heterogeneity of the microenvironment on therapeutic resistance is particularly complicated, which suggests a more challenging research direction. In addition, it has been reported that the three-dimensional (3D) organoid model derived from patient biopsies is more intuitive to fully understand the role of the TME in acquired resistance. Therefore, in this review, we have focused not only on the mechanisms and targets of therapeutic resistance related to the contents of the TME in HCC but also provide a comprehensive description of 3D models and how they contribute to the exploration of HCC therapies.

Up-Frameshift Suppressor 3 as a prognostic biomarker and correlated with immune infiltrates: A pan-cancer analysis

BACKGROUND

The mRNA expression of protein Up-Frameshift Suppressor 3 Homolog B (UPF3B) differ in different tumors. However, the clinical relevance of UPF3B in cancer patients, such as with prognosis, tumor stage, and levels of tumor-infiltrating immune cells remain unclear.

METHODS

We performed bioinformatics analysis of UPF3B with The Cancer Genome Atlas (TCGA) database (https://xenabrowser.net) and TIMER2.0 (Tumor Immune Estimation Resource 2.0, http://timer.comp-genomics.org/). UPF3B expression in 33 cancers versus counterpart normal tissues was analyzed using TCGA pan-cancer data. The influence of UPF3B in long-term prognosis was evaluated using Kaplan-Meier method, and the associations between UPF3B transcription levels and immune-related gene expression, immune cell infiltration, tumor microenvironment (TME) score are analyzed by spearman correlation analysis. Enrichment analysis of UPF3B was conducted using the R package "clusterProfiler."

RESULTS

The transcriptional level of UPF3B was dysregulated in the human pan-cancer dataset. A significant correlation was found between the expression of UPF3B and the pathological stage of Esophageal Carcinoma (ESCA), Kidney Chromophobe (KIHC), Liver Hepatocellular Carcinoma (LIHC), and Skin Cutaneous Melanoma (SKCM). Multiple cancer types with high transcriptional levels of UPF3B were associated with a significantly worse prognosis. The functions of expressed UPF3B gene are primarily related to ubiquitin mediated proteolysis, cell cycle, and mRNA surveillance pathway. Our results also show that immune cells infiltration and immunosuppressive markers such as CTLA-4, PD-1 and PD-L1 significantly correlate with UPF3B expression.

CONCLUSIONS

In the present study, we synthetically explored the expression status and prognostic significance of UPF3B, and the relationship with clinic characters and immune microenvironment across cancers. Our results may provide novel insights for UPF3B as an immunotherapeutic target and valuable prognostic biomarker in various malignant tumor.

The immunosuppressive tumor microenvironment in hepatocellular carcinoma-current situation and outlook

Hepatocellular carcinoma (HCC) is one of the most severe malignant tumors that threaten human health, and its incidence is still on the rise recently. In spite of the current emerging treatment strategies, the overall prognosis of liver cancer remains worrying. Currently, immunotherapy has become a new research-active spot. The emergence of immune checkpoints and targeted immune cell therapy can significantly improve the prognosis of HCC. To a large extent, the effect of this immunotherapy depends on the tumor immune microenvironment (TME), an intricate system in which cancer cells and other non-cancer cells display various interactions. Understanding the immunosuppressive situation of these cells, along with the malignant behavior of cancer cells, can assist us to design new therapeutic approaches against tumors. Therefore, it is necessary to clarify the TME of HCC for further improvement of clinical treatment. This review discussed the functions of several immunosuppressive cells and exosomes in the latest research progress of HCC, including cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs) and tumor-associated neutrophils (TANs) interacted actively to facilitate tumor progression. It further describes the treatment methods targeting them and the potential that needs to be explored in the future.

Overcoming resistance to immune checkpoint inhibitors in hepatocellular carcinoma: Challenges and opportunities

Hepatocellular carcinoma is one of the leading causes of cancer mortality globally, and its incidence is increasing. Immune checkpoint therapy has revolutionized the treatment of hepatocellular carcinoma over the past few years. However, only a limited proportion of patients with hepatocellular carcinoma respond to immunotherapy. Despite the significant breakthroughs, the molecular mechanisms that drive immune responses and evasion are largely unresolved. Predicting tumor response and resistance to immune checkpoint inhibitors is a significant challenge. In this review, we focus on the current research progress of immune checkpoint inhibitors in hepatocellular carcinoma. Importantly, this review highlights the underlying mechanisms of resistance to immune checkpoint inhibitors and summarizes potential strategies to overcome the resistance to immune checkpoint inhibitors in hepatocellular carcinoma.

Pharmacological modulation of myeloid-derived suppressor cells to dampen inflammation

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous cell population with potent suppressive and regulative properties. MDSCs’ strong immunosuppressive potential creates new possibilities to treat chronic inflammation and autoimmune diseases or induce tolerance towards transplantation. Here, we summarize and critically discuss different pharmacological approaches which modulate the generation, activation, and recruitment of MDSCs in vitro and in vivo, and their potential role in future immunosuppressive therapy.

The tumor microenvironment of hepatocellular carcinoma and its targeting strategy by CAR-T cell immunotherapy

Hepatocellular carcinoma (HCC) is the major subtype of liver cancer, which ranks sixth in cancer incidence and third in mortality. Although great strides have been made in novel therapy for HCC, such as immunotherapy, the prognosis remains less than satisfactory. Increasing evidence demonstrates that the tumor immune microenvironment (TME) exerts a significant role in the evolution of HCC and has a non-negligible impact on the efficacy of HCC treatment. In the past two decades, the success in hematological malignancies made by chimeric antigen receptor-modified T (CAR-T) cell therapy leveraging it holds great promise for cancer treatment. However, in the face of a hostile TME in solid tumors like HCC, the efficacy of CAR-T cells will be greatly compromised. Here, we provide an overview of TME features in HCC, discuss recent advances and challenges of CAR-T immunotherapy in HCC.

Neutrophils as potential therapeutic targets in hepatocellular carcinoma

The success of atezolizumab plus bevacizumab treatment contributed to a shift in systemic therapies for hepatocellular carcinoma (HCC) towards combinations that include cancer immunotherapeutic agents. Thus far, the principal focus of cancer immunotherapy has been on interrupting immune checkpoints that suppress antitumour lymphocytes. As well as lymphocytes, the HCC environment includes numerous other immune cell types, among which neutrophils are emerging as an important contributor to the pathogenesis of HCC. A growing body of evidence supports neutrophils as key mediators of the immunosuppressive environment in which some cancers develop, as well as drivers of tumour progression. If neutrophils have a similar role in HCC, approaches that target or manipulate neutrophils might have therapeutic benefits, potentially including sensitization of tumours to conventional immunotherapy. Several neutrophil-directed therapies for patients with HCC (and other cancers) are now entering clinical trials. This Review outlines the evidence in support of neutrophils as drivers of HCC and details their mechanistic roles in development, progression and metastasis, highlighting the reasons that neutrophils are well worth investigating despite the challenges associated with studying them. Neutrophil-modulating anticancer therapies entering clinical trials are also summarized.

HOXA7 promotes the metastasis of KRAS mutant colorectal cancer by regulating myeloid-derived suppressor cells

Background

KRAS mutation accounts for 30–50% of human colorectal cancer (CRC) cases. Due to the scarcity of effective treatment options, KRAS mutant CRC is difficult to treat in the clinic. Metastasis is still the major cause of the high mortality associated with KRAS mutant CRC, but the exact mechanism remains unclear. Here, we report a unique function of Homeobox 7 (HOXA7) in driving KRAS mutant CRC metastasis and explore therapeutic strategies for subpopulations of patients with this disease.

Methods

The expression of HOXA7 in a human CRC cohort was measured by immunohistochemistry. The function of HOXA7 in KRAS mutant CRC metastasis was analyzed with the cecum orthotopic model.

Results

Elevated HOXA7 expression was positively correlated with lymph node metastasis, distant metastasis, poor tumor differentiation, high TNM stage, and poor prognosis in CRC patients. Furthermore, HOXA7 was an independent prognostic marker in KRAS mutant CRC patients (P < 0.001) but not in KRAS wild-type CRC patients (P = 0.575). Overexpression of HOXA7 improved the ability of KRAS mutant CT26 cells to metastasize and simultaneously promoted the infiltration of myeloid-derived suppressor cells (MDSCs). When MDSC infiltration was blocked by a CXCR2 inhibitor, the metastasis rate of CT26 cells was markedly suppressed. The combination of the CXCR2 inhibitor SB265610 and programmed death-ligand 1 antibody (anti-PD-L1) could largely inhibit the metastasis of KRAS mutant CRC.

Conclusions

HOXA7 overexpression upregulated CXCL1 expression, which promoted MDSC infiltration. Interruption of this loop might provide a promising treatment strategy for HOXA7-mediated KRAS mutant CRC metastasis.

Tumor-intrinsic and immune modulatory roles of receptor-interacting protein kinases

Receptor-interacting protein kinase 1 (RIPK1) and RIPK3 are signaling adaptors that critically regulate cell death and inflammation. Tumors have adapted to subvert RIPK-dependent cell death, suggesting that these processes have key roles in tumor regulation. Moreover, RIPK-driven cancer cell death might bolster durable antitumor immunity. By contrast, there are examples in which RIPKs induce inflammation and aid tumor progression. Furthermore, the RIPKs can exert their effects on tumor growth through regulating the activity of immune effectors in the tumor microenvironment, thus highlighting the context-dependent roles of RIPKs. Here, we review recent advances in the regulation of RIPK activity in tumors and immune cells and how these processes coordinate with each other to control tumorigenesis.

RIP3 blockade prevents immune-mediated hepatitis through a myeloid-derived suppressor cell dependent mechanism

Autoimmune hepatitis (AIH) is an immune-mediated chronic inflammatory liver disease, and its pathogenesis is not fully understood. Our previous study discovered that receptor interacting protein kinase 3 (RIP3) is correlated with serum transaminase levels in AIH patients. However, its role and underlying mechanism in AIH are poorly understood. Here, we detected the increased expression and activation of RIP3 in livers of patients and animal models with AIH. The inhibition of RIP3 kinase by GSK872 prevented concanavalin A (ConA)-induced immune-mediated hepatitis (IMH) by reduced hepatic proinflammatory cytokines and immune cells including Th17 cells and macrophages. Further experiments revealed that RIP3 inhibition resulted in an increase in CD11b⁺Gr1⁺ myeloid-derived suppressor cells (MDSCs) with immunoregulatory properties in the liver, spleen, and peripheral blood. Moreover, the depletion of Gr-1⁺ MDSCs abrogated the protective effect and immune suppression function of GSK872 in ConA-induced IMH. Altogether, our data demonstrate that RIP3 blockade prevents ConA-induced IMH through promoting MDSCs infiltration. Inhibition of RIP3 kinase may be a novel therapeutic avenue for AIH treatment.

Cancer-cell-intrinsic mechanisms regulate MDSCs through cytokine networks

Immunotherapy has shifted the paradigm of cancer treatment. However, the majority of cancer patients display de novo or acquired resistance to immunotherapy. One of the main mechanisms of immunotherapy resistance is the immunosuppressive microenvironment dominated by the myeloid-derived suppressor cells (MDSCs). Emerging evidence demonstrates that genetic or epigenetic aberrations in cancer cells shape the accumulation and activation of MDSCs. Understanding this genotype-immunophenotype relationship is critical to the rational design of combination immunotherapy. Here, we review the mechanisms of how molecular changes in cancer cells induce recruitment and reprogram the function of tumor-infiltrating myeloid cells, particularly MDSCs. Tumor-infiltrating MDSCs elicit various pro-tumor functions to promote tumor cell fitness, immune evasion, angiogenesis, tissue remodeling, and metastasis. Through understanding the genotype-immunophenotype relationship between neoplastic cells and MDSCs, new approaches can be developed to tailor current immunotherapy strategies to improve cancer patient outcomes.

Lactate: The Mediator of Metabolism and Immunosuppression

The Warburg effect, one of the hallmarks of tumors, produces large amounts of lactate and generates an acidic tumor microenvironment via using glucose for glycolysis. As a metabolite, lactate not only serves as a substrate to provide energy for supporting cell growth and development but also acts as an important signal molecule to affect the biochemical functions of intracellular proteins and regulate the biological functions of different kinds of cells. Notably, histone lysine lactylation (Kla) is identified as a novel post-modification and carcinogenic signal, which provides the promising and potential therapeutic targets for tumors. Therefore, the metabolism and functional mechanism of lactate are becoming one of the hot fields in tumor research. Here, we review the production of lactate and its regulation on immunosuppressive cells, as well as the important role of Kla in hepatocellular carcinoma. Lactate and Kla supplement the knowledge gap in oncology and pave the way for exploring the mechanism of oncogenesis and therapeutic targets. Research is still needed in this field.

Roles of the CXCL8-CXCR1/2 Axis in the Tumor Microenvironment and Immunotherapy

In humans, Interleukin-8 (IL-8 or CXCL8) is a granulocytic chemokine with multiple roles within the tumor microenvironment (TME), such as recruiting immunosuppressive cells to the tumor, increasing tumor angiogenesis, and promoting epithelial-to-mesenchymal transition (EMT). All of these effects of CXCL8 on individual cell types can result in cascading alterations to the TME. The changes in the TME components such as the cancer-associated fibroblasts (CAFs), the immune cells, the extracellular matrix, the blood vessels, or the lymphatic vessels further influence tumor progression and therapeutic resistance. Emerging roles of the microbiome in tumorigenesis or tumor progression revealed the intricate interactions between inflammatory response, dysbiosis, metabolites, CXCL8, immune cells, and the TME. Studies have shown that CXCL8 directly contributes to TME remodeling, cancer plasticity, and the development of resistance to both chemotherapy and immunotherapy. Further, clinical data demonstrate that CXCL8 could be an easily measurable prognostic biomarker in patients receiving immune checkpoint inhibitors. The blockade of the CXCL8-CXCR1/2 axis alone or in combination with other immunotherapy will be a promising strategy to improve antitumor efficacy. Herein, we review recent advances focusing on identifying the mechanisms between TME components and the CXCL8-CXCR1/2 axis for novel immunotherapy strategies.

Targeting Immune Cells in the Tumor Microenvironment of HCC: New Opportunities and Challenges

Immune associated cells in the microenvironment have a significant impact on the development and progression of hepatocellular carcinoma (HCC) and have received more and more attention. Different types of immune-associated cells play different roles, including promoting/inhibiting HCC and several different types that are controversial. It is well known that immune escape of HCC has become a difficult problem in tumor therapy. Therefore, in recent years, a large number of studies have focused on the immune microenvironment of HCC, explored many mechanisms worth identifying tumor immunosuppression, and developed a variety of immunotherapy methods as targets, laying the foundation for the final victory in the fight against HCC. This paper reviews recent studies on the immune microenvironment of HCC that are more reliable and important, and provides a more comprehensive view of the investigation of the immune microenvironment of HCC and the development of more immunotherapeutic approaches based on the relevant summaries of different immune cells.

Landscape of Myeloid-derived Suppressor Cell in Tumor Immunotherapy

Myeloid-derived suppressor cells (MDSC) are a group of immature cells that produced by emergency myelopoiesis. Emerging evidences have identified the vital role of MDSC in cancer microenvironment, in which MDSC exerts both immunological and non-immunological activities to assist the progression of cancer. Advances in pre-clinical research have provided us the understanding of MDSC in cancer context from the perspective of molecular mechanism. In clinical scenario, MDSC and its subsets have been discovered to exist in peripheral blood and tumor site of patients from various types of cancers. In this review, we highlight the clinical value of MDSC in predicting prognosis of cancer patients and the responses of immunotherapies, therefore to propose the MDSC-inhibiting strategy in the scenario of cancer immunotherapies. Phenotypes and biological functions of MDSC in cancer microenvironment are comprehensively summarized to provide potential targets of MDSC-inhibiting strategy from the aspect of molecular mechanisms.

Therapeutic Values of Myeloid-Derived Suppressor Cells in Hepatocellular Carcinoma: Facts and Hopes

Simple Summary

Myeloid-derived suppressor cells restrict the effectiveness of immune-checkpoint inhibitors for a subset of patients mainly through thwarting T cell infiltration into tumor sites. Treatments targeting MDSCs have shown potent inhibitory effects on multiple tumors, including hepatocellular carcinoma. In this review, we summarize the pathological mechanisms of MDSCs and their clinical significance as prognostic and predictive biomarkers for HCC patients, and we provide the latest progress of MDSCs-targeting treatment in HCC.

Abstract

One of the major challenges in hepatocellular carcinoma (HCC) treatment is drug resistance and low responsiveness to systemic therapies, partly due to insufficient T cell infiltration. Myeloid-derived suppressor cells (MDSCs) are immature marrow-derived cell populations with heterogeneity and immunosuppression characteristics and are essential components of the suppressive tumor immune microenvironment (TIME). Increasing evidence has demonstrated that MDSCs are indispensable contributing factors to HCC development in a T cell-dependent or non-dependent manner. Clinically, the frequency of MDSCs is firmly linked to HCC clinical outcomes and the effectiveness of immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs). Furthermore, MDSCs can also be used as prognostic and predictive biomarkers for patients with HCC. Therefore, treatments reprograming MDSCs may offer potential therapeutic opportunities in HCC. Here, we recapitulated the dynamic relevance of MDSCs in the initiation and development of HCC and paid special attention to the effect of MDSCs on T cells infiltration in HCC. Finally, we pointed out the potential therapeutic effect of targeting MDSCs alone or in combination, hoping to provide new insights into HCC treatment.

Neutrophil-to-Apolipoprotein A1 Ratio Predicted Overall Survival in Hepatocellular Carcinoma Receiving Transarterial Chemoembolization

PURPOSE

The purpose of this study was to investigate the predictive capability of neutrophil-to-apolipoprotein A1 ratio (NAR) for predicting overall survival (OS) among patients with hepatocellular carcinoma (HCC) receiving transarterial chemoembolization (TACE).

PATIENTS AND METHODS

We investigated the clinical features of 554 patients with HCC receiving TACE and assessed NAR's predictive value for OS with 222 patients (the discovery cohort) and 332 patients (the validation cohort). The association of NAR with circulation lectin-type oxidized low-density lipoprotein receptor-1-positive (LOX-1+ ) polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) was illustrated.

RESULTS

Multivariate Cox regression revealed that lymphocyte count; Tumor, Node, Metastasis (TNM) stage; and NAR were independent prognostic factors in the discovery cohort. The validation cohort confirmed the independent prognostic value of TNM stage and NAR. Patients with low NAR (<2.7) displayed significantly increased OS in the discovery cohort (59.8 months vs. 21 months), the validation group (38.0 months vs. 23.6 months), and the total cohort (44.1 months vs. 22.0 months). A Cox proportional hazards model was used to combine Cancer of the Liver Italian Program (CLIP) score with discretized NAR. C-index illustrated that NAR-integrated CLIP score was the best model compared with NAR and CLIP score. Furthermore, NAR-CLIP presented superior predictive capacity for 10-, 20-, 30-, 40-, 50-, and 60-month survival compared with CLIP score by survival receiver-operator characteristic analysis in the discovery cohort, validation cohort, and total cohort. NAR was significantly associated with LOX-1+ PMN-MDSCs by linear regression.

CONCLUSION

This study identified NAR as an independent predictor for OS among patients with HCC receiving TACE. NAR reflected circulation LOX-1+ PMN-MDSC level.

IMPLICATIONS FOR PRACTICE

The present study identified neutrophil-to-apolipoprotein A1 ratio (NAR) as an independent predictor for overall survival among patients with hepatocellular carcinoma receiving transarterial chemoembolization. NAR reflected circulation level of lectin-type oxidized low-density lipoprotein receptor-1-positive polymorphonuclear myeloid-derived suppressor cells.

Myeloid-Derived Suppressor Cells: Implications in the Resistance of Malignant Tumors to T Cell-Based Immunotherapy

T lymphocytes function as major players in antigen-mediated cytotoxicity and have become powerful tools for exploiting the immune system in tumor elimination. Several types of T cell-based immunotherapies have been prescribed to cancer patients with durable immunological response. Such strategies include immune checkpoint inhibitors, adoptive T cell therapy, cancer vaccines, oncolytic virus, and modulatory cytokines. However, the majority of cancer patients still failed to take the advantage of these kinds of treatments. Currently, extensive attempts are being made to uncover the potential mechanism of immunotherapy resistance, and myeloid-derived suppressor cells (MDSCs) have been identified as one of vital interpretable factors. Here, we discuss the immunosuppressive mechanism of MDSCs and their contributions to failures of T cell-based immunotherapy. Additionally, we summarize combination therapies to ameliorate the efficacy of T cell-based immunotherapy.

SLC7A2 deficiency promotes hepatocellular carcinoma progression by enhancing recruitment of myeloid-derived suppressors cells

The main reason for poor prognosis in hepatocellular carcinoma (HCC) patients is high metastasis and recurrence. Cancer progression depends on a tumor-supportive microenvironment. Therefore, illustrating the mechanisms of tumor immunity in underlying HCC metastasis is essential. Here, we report a novel role of solute carrier family 7 member 2 (SLC7A2), a member of the solute carrier family, in HCC metastasis. The reduction of SLC7A2 was an independent and significant risk factor for the survival of HCC patients. Upregulation of SLC7A2 decreased HCC invasion and metastasis, whereas downregulation of SLC7A2 promoted HCC invasion and metastasis. We further found that deficient SLC7A2 medicated the upregulation of CXCL1 through PI3K/Akt/NF-kκB pathway to recruit myeloid-derived suppressor cells (MDSCs), exerting tumor immunosuppressive effect. Moreover, we found that G9a-mediated di-methylation of H3K9 (H3K9me2) silenced the expression of SLC7A2 to suppress HCC metastasis and immune escape. In conclusion, G9a-mediated silencing of SLC7A2 exerts unexpected functions in cancer metastasis by fostering a tumor-supportive microenvironment through CXCL1 secretion and MDSCs recruitment. Thus, SLC7A2 may provide new mechanistic insight into the cancer-promoting property of MDSCs.

Reduced CXCL1 production by endogenous IL-37 expressing dendritic cells does not affect T cell activation

The dendritic cell (DC)-derived cytokine profile contributes to naive T cell differentiation, thereby directing the immune response. IL-37 is a cytokine with anti-inflammatory characteristics that has been demonstrated to induce tolerogenic properties in DC. In this study we aimed to evaluate the influence of IL-37 on DC–T cell interaction, with a special focus on the role of the chemokine CXCL1. DC were cultured from bone marrow of human IL-37 transgenic (hIL-37Tg) or WT mice. The phenotype of unstimulated and LPS-stimulated DC was analyzed (co-stimulatory molecules and MHCII by flow cytometry, cytokine profile by RT-PCR and ELISA), and T cell stimulatory capacity was assessed in mixed lymphocyte reaction. The role of CXCL1 in T cell activation was analyzed in T cell stimulation assays with anti-CD3 or allogeneic DC. The expression of the co-stimulatory molecules CD40, CD80 and CD86, and of MHCII in LPS-stimulated DC was not affected by endogenous expression of IL-37, whereas LPS-stimulated hIL-37Tg DC produced less CXCL1 compared to LPS-stimulated WT DC. T cell stimulatory capacity of LPS-matured hIL-37Tg DC was comparable to that of WT DC. Recombinant mouse CXCL1 did not increase T cell proliferation either alone or in combination with anti-CD3 or allogeneic DC, nor did CXCL1 affect the T cell production of interferon-γ and IL-17. Endogenous IL-37 expression does not affect mouse DC phenotype or subsequent T cell stimulatory capacity, despite a reduced CXCL1 production. In addition, we did not observe an effect of CXCL1 in T cell proliferation or differentiation.

Receptor-interacting protein in malignant digestive neoplasms

A deep and comprehensive understanding of factors that contribute to cancer initiation, progression, and evolution is of essential importance. Among them, the serine/threonine and tyrosine kinase-like kinases, also known as receptor interacting proteins (RIPs) or receptor interacting protein kinases (RIPKs), is emerging as important tumor-related proteins due to its complex regulation of cell survival, apoptosis, and necrosis. In this review, we mainly review the relevance of RIP to various malignant digestive neoplasms, including esophageal cancer, gastric cancer, colorectal cancer, hepatocellular carcinoma, gallbladder cancer, cholangiocarcinoma, and pancreatic cancer. Consecutive research on RIPs and its relationship with malignant digestive neoplasms is required, as it ultimately conduces to the etiology and treatment of cancer.

GDC-0326 Enhances the Effects of 5-Fu in Colorectal Cancer Cells by Inducing Necroptotic Death

AIM

Chemoresistance to 5-fluorouracil (5-Fu) is common in colorectal cancer (CRC). Programmed necrosis (necroptosis) is an alternative form of programmed cell death regulated by receptor-interacting protein kinase (RIPK) 1 and 3, assumed as a novel target of cancer therapy. In this study, we aimed to explore whether a novel small molecular agent GDC-0326 could facilitate the effect of 5-Fu through necroptosis.

MAIN METHODS

Cell Counting Kit-8 (CCK-8) assay and colony formation were performed to confirm the function of GDC-0326 in CRC cells. Western blot and immunofluorescence were conducted to measure the altered expressions of RIPK1/RIPK3 induced by GDC-0326. Subcutaneous tumor models were used to evaluate the chemotherapeutic effects and concomitant side effects of GDC-0326 in vivo.

KEY FINDINGS

We found that GDC-0326 effectively suppressed the growth of CRC cells in a dose-dependent manner. The induction of necroptosis by GDC-0326 was correlated with the modulation of RIPK1 and RIPK3. Necrostatin-1 and GSK-872, inhibitors of RIPK1 and RIPK3, respectively, could rescue the cell death induced by GDC-0326. In addition, in vitro and in vivo studies showed that 5-Fu plus GDC-0326 evinced a better antitumor efficacy by suppressing tumor growth and increasing tumor necrosis with no increased toxicity.

SIGNIFICANCE

This study demonstrates that GDC-0326 plus 5-Fu has augmented antitumor efficacy and acceptable safety, which might be a promising therapeutic strategy for CRC patients in the future.

Homeobox B5 promotes metastasis and poor prognosis in Hepatocellular Carcinoma, via FGFR4 and CXCL1 upregulation

Background: Since metastasis remains the main reason for HCC-associated death, a better understanding of molecular mechanism underlying HCC metastasis is urgently needed. Here, we elucidated the role of Homeobox B5 (HOXB5), a member of the HOX transcriptional factor family, in promoting HCC metastasis.

Method: The expression of HOXB5 and its functional targets fibroblast growth factor receptor 4 (FGFR4) and C-X-C motif chemokine ligand 1 (CXCL1) were detected by immunohistochemistry. Luciferase reporter and chromatin immunoprecipitation assays were performed to measure the transcriptional regulation of target genes by HOXB5. The effects of FGFR4 and CXCL1 on HOXB5-mediated metastasis were analyzed by an orthotopic metastasis model.

Results: Elevated expression of HOXB5 had a positive correlation with poor tumour differentiation, higher TNM stage, and indicated unfavorable prognosis. Overexpression of HOXB5 promoted HCC metastasis through transactivating FGFR4 and CXCL1 expression, whereas knockdown of FGFR4 and CXCL1 decreased HOXB5-enhanced HCC metastasis. Moreover, HOXB5 overexpression in HCC cells promoted myeloid derived suppressor cells (MDSCs) infiltration through CXCL1/CXCR2 axis. Either depletion of MDSCs by anti-Gr1 or blocking CXCL1-CXCR2 axis by CXCR2 inhibitor impaired HOXB5-mediated HCC metastasis. In addition, fibroblast growth factor 19 (FGF19) contributed to the HOXB5 upregulation through PI3K/AKT/HIF1α pathway. Overexpression of FGF15 (an analog of FGF19 in mouse) promoted HCC metastasis, whereas knockdown of HOXB5 significantly inhibited FGF15-enhanced HCC metastasis in immunocompetent mice. HOXB5 expression was positively associated with CXCL1 expression and intratumoral MDSCs accumulation in human HCC tissues. Patients who co-expressed HOXB5/CXCL1 or HOXB5/CD11b exhibited the worst prognosis. Furthermore, the combination of FGFR4 inhibitor BLU-554 and CXCR2 inhibitor SB265610 dramatically decreased HOXB5-mediated HCC metastasis.

Conclusion: HOXB5 was a potential prognostic biomarker in HCC patients and targeting this loop may provide a promising treatment strategy for the inhibition of HOXB5-mediated HCC metastasis.

Innate immune cells and their interaction with T cells in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor and is associated with necroinflammation driven by various immune cells, such as dendritic cells, macrophages and natural killer cells. Innate immune cells can directly affect HCC or regulate the T-cell responses that mediate HCC. In addition, innate immune cells and T cells are not isolated, which means the interaction between them is important in the HCC microenvironment. Considering the current unsatisfactory efficacy of immunotherapy in patients with HCC, understanding the relationship between innate immune cells and T cells is necessary. In the present review the roles and clinical value of innate immune cells that have been widely reported to be involved in HCC, including dendritic cells, macrophages (including kupffer cells), neutrophils, eosinophils, basophils and innate lymphoid cells and the crosstalk between the innate and adaptive immune responses in the antitumor process have been discussed. The present review will facilitate researchers in understanding the importance of innate immune cells in HCC and lead to innovative immunotherapy approaches for the treatment of HCC.

KIAA1522 Promotes the Progression of Hepatocellular Carcinoma via the Activation of the Wnt/β-Catenin Signaling Pathway

Purpose

KIAA1522 was previously identified to play a crucial role in cancer development and progression. However, its functions and underlying mechanisms in hepatocellular carcinoma (HCC) remain elusive.

Materials and Methods

To elucidate the role of KIAA1522 in HCC, its expression was assessed using The Cancer Genome Atlas and GEPIA databases. Next, these results were validated by quantitative reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemistry of HCC tissues and cell lines. Flow cytometry, CCK-8, EDU, colony formation, Transwell invasion, and wound healing assays were performed to explore the function of KIAA1522 in HCC in vivo and in vitro. Finally, gene set enrichment analysis was used to identify the pathways involved.

Results

Our results demonstrated that KIAA1522 was highly expressed in HCC tissues and cell lines. Furthermore, KIAA1522 overexpression was associated with unfavorable clinicopathological characteristics. Survival analyses revealed that KIAA1522 overexpression predicted lower recurrence-free and overall survival rates in patients with HCC. Functional studies suggested that KIAA1522 facilitated HCC proliferation, migration, and invasion both in vitro and in vivo. Moreover, KIAA1522 up-regulated the Wnt/β-catenin signaling pathway, as confirmed by TOP-flash/FOP-flash luciferase reporter assays and Western blotting.

Conclusion

In conclusion, we highlighted the oncogenic role of KIAA1522 in HCC and determined its potential as a therapeutic target for HCC.

Overexpression of COL24A1 in Hepatocellular Carcinoma Predicts Poor Prognosis: A Study Based on Multiple Databases, Clinical Samples and Cell Lines

Purpose

Hepatocellular carcinoma (HCC) ranks as the second leading cause of cancer-related deaths worldwide and its incidence tends to increase globally. Current biomarkers can hardly reflect diagnostic significance and therapeutic efficiency accurately. The role of collagen 24A1 (COL24A1) in HCC, as a member of the collagen family, remains unclear and needs to be proved.

Methods

HCC-associated RNA sequencing datasets were obtained from The Cancer Genome Atlas (TCGA), International Cancer Genome Consortium (ICGC) and Oncomine databases. R language was used to screen and analyze the differential expression genes (DEGs). Gene Ontology (GO) pathway analyses of DEGs were carried out using g:profiler. Then, the STRING database and cytoscape software were applied to estimate the correlations between DEGs. GEPIA and HCCDB database were used to verify and analyze these results. Finally, qPCR and immunohistochemistry staining on clinical samples and HCC cell lines were conducted to further verify the above results.

Results

The expression of COL24A1 in HCC tissues was significantly higher than that in normal hepatic (NH) tissues. The analysis of TCGA and Oncomine database samples proved that COL24A1 expression was connected with tumor grade, tumor stage and pathologic stage. Meanwhile, the overall survival (OS) curve also validated that high expression of COL24A1 indicated poor prognosis. And the above results have been verified in our clinical samples and HCC cell lines. Furthermore, there is a significant increase of the expression of COL24A1 in various tumors. COL24A1, together with other interactive proteins, has a significant effect on the prognosis of HCC.

Conclusion

Overall, COL24A1 may be an oncogene in the development of HCC. Also, the overexpression of COL24A1 in HCC may help diagnose HCC and evaluate prognosis.

Increased Expression of Myeloid-Derived Suppressor Cells in Patients with HBV-Related Hepatocellular Carcinoma

METHODS

The percentages of MDSCs, IFN-γ-producing CD4 and CD8 T cells in the peripheral blood of HCC patients, chronic hepatitis B (CHB) patients, and healthy controls (HC) were determined by flow cytometry. The serum concentrations of IL-10 and TNF-α were determined by ELISA. The association of the percentages of MDSCs with tumor burden, liver function parameters, systemic inflammation-related indexes, and IFN-γ-producing T cells was assessed.

RESULTS

The percentages of MDSCs and PMN-MDSCs were significantly higher in HCC patients than those in CHB patients and HC. The level of MDSCs was correlated with indirect bilirubin and prealbumin, as well as systemic inflammation response index, monocyte/lymphocyte ratio, and monocyte counts. The frequency of IFN-γ-producing CD8 T cells of HCC patients was lower than that of HC. However, there was no relationship between MDSCs and IFN-γ-producing CD8 T cells. The level of IL-10 in HCC patients was significantly higher than that in CHB patients.

CONCLUSION

MDSCs seem to play an important role in the process leading from chronic HBV infection to HCC. Early inhibiting these cells could affect tumor progression.

A signature of 33 immune-related gene pairs predicts clinical outcome in hepatocellular carcinoma

Objective

Hepatocellular carcinoma (HCC) has become the second most common tumor type that contributes to cancer‐related death worldwide. The study aimed to establish a robust immune‐related gene pair (IRGP) signature for predicting the prognosis of HCC patients.

Methods

Two RNA‐seq datasets (The Cancer Genome Atlas Program and International Cancer Genome Consortium) and one microarray dataset (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE14520) were included in this study. We used a series of immune‐related genes from the ImmPort database to construct gene pairs. Lasso penalized Cox proportional hazards regression was employed to develop the best prognostic signature. We assigned patients into two groups with low immune risk and high immune risk. Then, the prognostic ability of the signature was evaluated by a log‐rank test and a Cox proportional hazards regression model.

Results

After 1000 iterations, the 33‐immune gene pair model obtained the highest frequency. As a result, we chose the 33 immune gene pairs to establish the immune‐related prognostic signature. As we expected, the immune‐related signature accurately predicted the prognosis of HCC patients, and high‐risk groups showed poor prognosis in the training datasets and testing datasets as well as in the validation datasets. Furthermore, the immune‐related gene pair (IRGP) signature also showed higher predictive accuracy than three existing prognostic signatures.

Conclusion

Our prognostic signature, which reflects the link between the immune microenvironment and HCC patient outcome, is promising for prognosis prediction in HCC.

Cobalt Chloride Induced Apoptosis by Inhibiting GPC3 Expression via the HIF-1α/c-Myc Axis in HepG2 Cells

Purpose

To investigate the role of glypican-3 (GPC3) in cobalt chloride (CoCl₂)-induced cell apoptosis in hepatocellular carcinoma.

Methods

HepG2 cells were treated with CoCl₂ in the absence or presence of GPC3 plasmid transfection. Cell viability and apoptosis were assessed by MTT assay and flow cytometry, respectively. The expression of GPC3, hypoxia-inducible factor 1α (HIF-1α), c-myc, sp1, poly-ADP-ribose polymerase (PARP) and caspase-3 was determined by real-time PCR, Western blotting, and immunofluorescence after the cells were treated with different concentrations of CoCl₂ or siRNA targeting HIF-1α.

Results

CoCl₂ significantly inhibited the proliferation of HepG2 cells and induced apoptosis. Additionally, the expression of GPC3 mRNA and protein was decreased, and overexpression of GPC3 attenuated the tumour inhibiting effects. Further studies showed that CoCl₂ increased the expression of HIF-1α while reducing the expression of sp1 and c-myc; knockdown of HIF-1α elevated the expression of GPC3, sp1, and c-myc.

Conclusion

CoCl₂ inhibited the growth of HepG2 cells through downregulation of GPC3 expression via the HIF-1α/c-myc axis.

Mouse Models for Immunotherapy in Hepatocellular Carcinoma

Liver cancer is one of the dominant causes of cancer-related mortality, and the survival rate of liver cancer is among the lowest for all cancers. Immunotherapy for hepatocellular carcinoma (HCC) has yielded some encouraging results, but the percentage of patients responding to single-agent therapies remains low. Therefore, potential directions for improved immunotherapies include identifying new immune targets and checkpoints and customizing treatment procedures for individual patients. The development of combination therapies for HCC is also crucial and urgent and, thus, further studies are required. Mice have been utilized in immunotherapy research due to several advantages, for example, being low in cost, having high success rates for inducing tumor growth, and so on. Moreover, immune-competent mice are used in immunotherapy research to clarify the role that the immune system plays in cancer growth. In this review paper, the advantages and disadvantages of mouse models for immunotherapy, the equipment that are used for monitoring HCC, and the cell strains used for inducing HCC are reviewed.

C-X-C chemokine receptor 2 correlates with unfavorable prognosis and facilitates malignant cell activities via activating JAK2/STAT3 pathway in non-small cell lung cancer

This study aimed to investigate the correlation of C-X-C chemokine receptor 2 (CXCR2) with clinicopathological characteristics and survival in non-small cell lung cancer (NSCLC) patients and further explore its effect on proliferation, apoptosis, invasion, stemness, chemosensitivity as well as JAK2/STAT3 pathway in NSCLC cells. The expression of CXCR2 in tumor tissues and adjacent tissues from 340 NSCLC patients received surgery was detected by immunohistochemistry. CXCR2 overexpression and knockdown were constructed through plasmid transfection and the effect of CXCR2 dysregulation on cell proliferation, apoptosis, invasion, stemness, chemosensitivity as well as its regulatory effect on JAK2/STAT signaling pathway was assessed in NCI-H1437 cells and NCI-H1299 cells. CXCR2 expression was higher in tumor tissues than that in paired adjacent tissues, and it was correlated with poor pathological differentiation, greater tumor size, lymph node metastasis, higher TNM stage and poor survival in NSCLC patients. In vitro, CXCR2 expression was increased in human NSCLC cell lines compared with human normal lung bronchus epithelial cells. CXCR2 promoted cell proliferation and invasion, while suppressed cell apoptosis in NCI-H1437/NCI-H1299 cells. Additionally, CXCR2 increased CD133⁺ cell rate and cell sphere-forming ability, while reduced chemosensitivity to cisplatin and gemcitabine in NCI-H1437/NCI-H1299 cells. Besides, CXCR2 activated the JAK2/STAT3 signaling pathway in NCI-H1437/NCI-H1299 cells. In conclusion, the clinical implication and the molecular function of CXCR2 discovered in our study reveal the potential of CXCR2 as a future target for disease monitoring and treatment of NSCLC.