The local liver ablation with pulsed electric field stimulate systemic immune reaction against hepatocellular carcinoma (HCC) with time-dependent cytokine profile

Present and future of metal nanoparticles in tumor ablation therapy

Cancer is an important factor affecting the quality of human life as well as causing death. Tumor ablation therapy is a minimally invasive local treatment modality with unique advantages in treating tumors that are difficult to remove surgically. However, due to its physical and chemical characteristics and the limitation of equipment technology, ablation therapy cannot completely kill all tumor tissues and cells at one time; moreover, it inevitably damages some normal tissues in the surrounding area during the ablation process. Therefore, this technology cannot be the first-line treatment for tumors at present. Metal nanoparticles themselves have good thermal and electrical conductivity and unique optical and magnetic properties. The combination of metal nanoparticles with tumor ablation technology, on the one hand, can enhance the killing and inhibiting effect of ablation technology on tumors by expanding the ablation range; on the other hand, the ablation technology changes the physicochemical microenvironment such as temperature, electric field, optics, oxygen content and pH in tumor tissues. It helps to stimulate the degree of local drug release of nanoparticles and increase the local content of anti-tumor drugs, thus forming a synergistic therapeutic effect with tumor ablation. Recent studies have found that some specific ablation methods will stimulate the body's immune response while physically killing tumor tissues, generating a large number of immune cells to cause secondary killing of tumor tissues and cells, and with the assistance of metal nanoparticles loaded with immune drugs, the effect of this anti-tumor immunotherapy can be further enhanced. Therefore, the combination of metal nanoparticles and ablative therapy has broad research potential. This review covers common metallic nanoparticles used for ablative therapy and discusses in detail their characteristics, mechanisms of action, potential challenges, and prospects in the field of ablation.

Friend or Foe? Locoregional Therapies and Immunotherapies in the Current Hepatocellular Treatment Landscape

Over the last several decades, a number of new treatment options for patients with hepatocellular carcinoma (HCC) have been developed. While treatment decisions for some patients remain clear cut, a large numbers of patients have multiple treatment options, and it can be hard for multidisciplinary teams to come to unanimous decisions on which treatment strategy or sequence of treatments is best. This article reviews the available data with regard to two treatment strategies, immunotherapies and locoregional therapies, with a focus on the potential of locoregional therapies to be combined with checkpoint inhibitors to improve outcomes in patients with locally advanced HCC. In this review, the available data on the immunomodulatory effects of locoregional therapies is discussed along with available clinical data on outcomes when the two strategies are combined.

Dynamic Changes of Cytokine Profiles and Their Correlation With Tumor Recurrence Following Thermal Ablation in Hepatocellular Carcinoma

The 5-year recurrence rate of thermal ablation for hepatocellular carcinoma (HCC) is high, and whether this treatment strategy induces systemic immune response remains elusive. This study aimed to investigate the effects of thermal ablation on HCC patients' cytokine profiles and to explore the correlation of cytokine profiles with tumor recurrence after ablation. A total of 22 HCC patients were included in this prospective study. The levels of 27 cytokines in the peripheral blood of HCC patients were measured before ablation (baseline), week 1, and week 4 after ablation using a Bio-Plex Pro Human Cytokine 27-plex Assay kit. Cytokines showed different dynamic changing trends after ablation treatment. It was found that the level of IL-6 was significantly elevated at week 1 and returned to the baseline level at week 4 after ablation. The level of IL-10 was slightly reduced at week 1 and significantly decreased at week 4. The levels of MCP-1, macrophage inflammatory protein-1β (MIP-1β), and TNF-α were similarly reduced at week 1 and increased at week 4. The levels of IL-17, platelet-derived growth factor-BB (PDGF-BB), and regulated upon activation, normal T cell expressed and secreted (RANTES) showed little to no change at week 1 while an observable increase at week 4. Patients with a high IL-10 level (2.99 pg/ml) at baseline and low levels of TNF-α (20.4 pg/ml), PDGF-BB (107.78 pg/ml), and RANTES (2303.94 pg/ml) at week 4 were at risk of tumor recurrence during 1-year follow-up. The results suggested that thermal ablation activated systemic immune responses by changing the levels of cytokines. The results also demonstrated that measurement of IL-10 at baseline, TNF-α, PDGF-BB, and RANTES at week 4 after ablation might predict the risk of tumor recurrence.

Effect of pulsed field ablation on solid tumor cells and microenvironment

Pulsed field ablation can increase membrane permeability and is an emerging non-thermal ablation. While ablating tumor tissues, electrical pulses not only act on the membrane structure of cells to cause irreversible electroporation, but also convert tumors into an immune active state, increase the permeability of microvessels, inhibit the proliferation of pathological blood vessels, and soften the extracellular matrix thereby inhibiting infiltrative tumor growth. Electrical pulses can alter the tumor microenvironment, making the inhibitory effect on the tumor not limited to short-term killing, but mobilizing the collective immune system to inhibit tumor growth and invasion together.

Induction of Bystander and Abscopal Effects after Electroporation-Based Treatments

Simple Summary

The delivery of electric field to tumor cells or nodules induces cell electroporation that allows intracellular delivery of cytotoxic agents and eventually inhibits tumor growth. In this study, we showed that intracellular delivery of calcium ions and anticancer drug bleomycin not only kills the cells but also has a negative bystander effect on indirectly treated cells. We also showed that, when directly applied to one tumor, these treatments can inhibit the growth of a second, non-electroporated tumor.

Abstract

Electroporation-based antitumor therapies, including bleomycin electrotransfer, calcium electroporation, and irreversible electroporation, are very effective on directly treated tumors, but have no or low effect on distal nodules. In this study, we aimed to investigate the abscopal effect following calcium electroporation and bleomycin electrotransfer and to find out the effect of the increase of IL-2 serum concentration by muscle transfection. The bystander effect was analyzed in in vitro studies on 4T1tumor cells, while abscopal effect was investigated in an in vivo setting using Balb/c mice bearing 4T1 tumors. ELISA was used to monitor IL-2 serum concentration. We showed that, similarly to cell treatment with bleomycin electrotransfer, the bystander effect occurs also following calcium electroporation and that these effects can be combined. Combination of these treatments also resulted in the enhancement of the abscopal effect in vivo. Since these treatments resulted in an increase of IL-2 serum concentration only in mice bearing one but not two tumors, we increased IL-2 serum concentration by muscle transfection. Although this did not enhance the abscopal effect of combined tumor treatment using calcium electroporation and bleomycin electrotransfer, boosting of IL-2 serum concentration had a significant inhibitory effect on directly treated tumors.

Electroporation and Immunotherapy-Unleashing the Abscopal Effect

Simple Summary

Electrochemotherapy and irreversible electroporation are primarily used for treating patients with cutaneous and subcutaneous tumors and pancreatic cancer, respectively. Increasing numbers of studies have shown that the treatments may elicit an immune response in addition to eliminating the tumor cells. The purpose of this review is to give an in-depth introduction to the electroporation-induced immune response and the local and peripheral immune systems, and to describe the various studies investigating the combination of electroporation and immunotherapy. The review may help guide and inspire the design of future clinical trials investigating the potential synergy of electroporation and immunotherapy in cancer treatment.

Abstract

The discovery of electroporation in 1968 has led to the development of electrochemotherapy (ECT) and irreversible electroporation (IRE). ECT and IRE have been established as treatments of cutaneous and subcutaneous tumors and locally advanced pancreatic cancer, respectively. Interestingly, the treatment modalities have been shown to elicit immunogenic cell death, which in turn can induce an immune response towards the tumor cells. With the dawn of the immunotherapy era, the potential of combining ECT and IRE with immunotherapy has led to the launch of numerous studies. Data from the first clinical trials are promising, and new combination regimes might change the way we treat tumors characterized by low immunogenicity and high levels of immunosuppression, such as melanoma and pancreatic cancer. In this review we will give an introduction to ECT and IRE and discuss the impact on the immune system. Additionally, we will present the results of clinical and preclinical trials, investigating the combination of electroporation modalities and immunotherapy.

High-frequency irreversible electroporation brain tumor ablation: exploring the dynamics of cell death and recovery

Improved therapeutics for malignant brain tumors are urgently needed. High-frequency irreversible electroporation (H-FIRE) is a minimally invasive, nonthermal tissue ablation technique, which utilizes high-frequency, bipolar electric pulses to precisely kill tumor cells. The mechanisms of H-FIRE-induced tumor cell death and potential for cellular recovery are incompletely characterized. We hypothesized that tumor cells treated with specific H-FIRE electric field doses can survive and retain proliferative capacity. F98 glioma and LL/2 Lewis lung carcinoma cell suspensions were treated with H-FIRE to model primary and metastatic brain cancer, respectively. Cell membrane permeability, apoptosis, metabolic viability, and proliferative capacity were temporally measured using exclusion dyes, condensed chromatin staining, WST-8 fluorescence, and clonogenic assays, respectively. Both tumor cell lines exhibited dose-dependent permeabilization, with 1,500 V/cm permitting and 3,000 V/cm inhibiting membrane recovery 24 h post-treatment. Cells treated with 1,500 V/cm demonstrated significant and progressive recovery of apoptosis and metabolic activity, in contrast to cells treated with higher H-FIRE doses. Cancer cells treated with recovery-permitting doses of H-FIRE maintained while those treated with recovery-inhibiting doses lost proliferative capacity. Taken together, our data suggest that H-FIRE induces reversible and irreversible cellular damage in a dose-dependent manner, and the presence of dose-dependent recovery mechanisms permits tumor cell proliferation.

Irreversible Electroporation: An Emerging Immunomodulatory Therapy on Solid Tumors

Irreversible electroporation (IRE), a novel non-thermal ablation technique, is utilized to ablate unresectable solid tumors and demonstrates favorable safety and efficacy in the clinic. IRE applies electric pulses to alter the cell transmembrane voltage and causes nanometer-sized membrane defects or pores in the cells, which leads to loss of cell homeostasis and ultimately results in cell death. The major drawbacks of IRE are incomplete ablation and susceptibility to recurrence, which limit its clinical application. Recent studies have shown that IRE promotes the massive release of intracellular concealed tumor antigens that become an “in-situ tumor vaccine,” inducing a potential antitumor immune response to kill residual tumor cells after ablation and inhibiting local recurrence and distant metastasis. Therefore, IRE can be regarded as a potential immunomodulatory therapy, and combined with immunotherapy, it can exhibit synergistic treatment effects on malignant tumors, which provides broad application prospects for tumor treatment. This work reviewed the current status of the clinical efficacy of IRE in tumor treatment, summarized the characteristics of local and systemic immune responses induced by IRE in tumor-bearing organisms, and analyzed the specific mechanisms of the IRE-induced immune response. Moreover, we reviewed the current research progress of IRE combined with immunotherapy in the treatment of solid tumors. Based on the findings, we present deficiencies of current preclinical studies of animal models and analyze possible reasons and solutions. We also propose possible demands for clinical research. This review aimed to provide theoretical and practical guidance for the combination of IRE with immunotherapy in the treatment of malignant tumors.

Interventional Radiology Image-Guided Locoregional Therapies (LRTs) and Immunotherapy for the Treatment of HCC

Image-guided locoregional therapies (LRTs) are a crucial asset in the treatment of hepatocellular carcinoma (HCC), which has proven to be characterized by an impaired antitumor immune status. LRTs not only directly destroy tumor cells but also have an immunomodulating role, altering the tumor microenvironment with potential systemic effects. Nevertheless, the immune activation against HCC induced by LRTs is not strong enough on its own to generate a systemic significant antitumor response, and it is incapable of preventing tumor recurrence. Currently, there is great interest in the possibility of combining LRTs with immunotherapy for HCC, as this combination may result in a mutually beneficial and synergistic relationship. On the one hand, immunotherapy could amplify and prolong the antitumoral immune response of LRTs, reducing recurrence cases and improving outcome. On the other hand, LTRs counteract the typical immunosuppressive HCC microenvironment and status and could therefore enhance the efficacy of immunotherapy. Here, after reviewing the current therapeutic options for HCC, we focus on LRTs, describing for each of them the technique and data on its effect on the immune system. Then, we describe the current status of immunotherapy and finally report the recently published and ongoing clinical studies testing this combination.

Immunological effect of irreversible electroporation on hepatocellular carcinoma

Background

This study intends to investigate the immunological effects of tumor ablation with irreversible electroporation (IRE).

Methods

We evaluated the systemic immune response in patients with hepatocellular carcinoma (HCC) after IRE treatment. Furthermore, we analyzed the tumor infiltrating T lymphocytes and the level of serum cytokines in IRE and control groups of tumor-bearing mice.

Results

We observed that IRE induced an increase in WBC, neutrophil and monocyte counts and a decrease in lymphocyte count 1 day post-IRE and returned to baseline values within 7 days in the patients. Meanwhile, circulating CD4⁺ T cell subsets, but not CD8⁺, decreased 1 day post-IRE. The activated T cells and natural killer (NK) cells increased, and regulatory T (Treg) cells decreased. Furthermore, a significant increase in cytotoxic CD8⁺ T cells infiltration was observed on ablative tumors in mice. The level of serum IFN-γ also significantly increased in the IRE group.

Conclusions

Our study demonstrated that IRE upregulated activated T cells and downregulated Tregs in the peripheral blood of patients. Meanwhile, the results from the animal model indicated that IRE could induce antitumor adaptive immunity dominated by the infiltration of cytotoxic CD8⁺ T cells into the tumors, accompanied by reduced Tregs.

Effects of miRNA-140 on the Growth and Clinical Prognosis of SMMC-7721 Hepatocellular Carcinoma Cell Line

Background

A growing number of studies have suggested that microRNAs exert an essential role in the development and occurrence of multiple tumours and act as crucial regulators in various biological processes. However, the expression and function of miRNA-140 in hepatocellular carcinoma (HCC) cells are not yet adequately identified and manifested.

Methods

The expression of miRNA-140 was determined in HCC tissues and adjacent nontumour tissues by quantitative real-time polymerase chain reaction (qRT-PCR). Kaplan-Meier survival analysis and Cox regression analysis were performed to explore the correlation between miRNA-140 expression level and the survival rate of patients with HCC. Additionally, overexpression experiments were conducted to investigate the biological role of miRNA-140 in HCC cells. Bioinformatics was used to predict the related target genes and pathways of miRNA-140.

Results

QRT-PCR results signified that the expression level of miRNA-140 in HCC was lower than that of adjacent normal tissues (P < 0.0001). Compared with the control group, the SMMC-7721 HCC cells in the miRNA-140 mimic group had a decrease in proliferation, migration, and invasion (P < 0.05), whereas those in the miRNA-140 inhibitor group had an increase in proliferation, migration, and invasion (P < 0.05). Cell cycle arrest occurred in the G0/1 phase. Prognosis analysis showed that the expression level of miRNA-140 was not related to the prognosis of HCC. Furthermore, the Kaplan-Meier test revealed that patients with lower miRNA-140 expression levels in liver cancer tissue had significantly shorter disease-free survival (DFS, P = 0.004) and overall survival (OS) times (P = 0.010) after hepatectomy. Cox regression analysis further indicated that miRNA-140 was an independent risk factor that may affect the DFS (P = 0.004) and OS times (P = 0.014) of patients after hepatectomy. Our results suggested that miRNA-140 might be a crucial regulator involved in the HCC progression and is thus considered a potential prognostic biomarker and therapeutic target for HCC.

Irreversible electroporation induces CD8+ T cell immune response against post-ablation hepatocellular carcinoma growth

Ablative treatment evokes antitumor immunity, but knowledge on the emerging irreversible electroporation (IRE)-induced immunity in hepatocellular carcinoma (HCC) is limited. To investigate the immune effects induced by IRE and its role in preventing post-ablation HCC progression, a C57BL/6J mouse model bearing subcutaneous H22 hepatoma was employed. IRE treatment significantly suppresses HCC growth, and treated mice are tumor-free after secondary tumor injection and show increased splenic interferon-gamma (IFN-γ)+CD8⁺ T cells. Additionally, more CD8⁺ T and dendritic cells, but not CD4⁺ T, B or NK cells, infiltrate into peri-ablation zones after IRE at day 7. Depletion of CD8⁺ T cells induces local tumor regrowth and distant metastasis after IRE. Vaccination using IRE-processed H22 lysates prevents tumorigenesis in mice, suggesting a protective immune response. IRE also alleviates immunosuppression by reducing local and splenic Treg and PD-1⁺ T cells. Regarding mechanism, IRE induces cell necrosis and significant release of danger-associated molecular patterns including ATP, high mobility group box 1 and calreticulin that are pivotal to CD8⁺ T cell immunity. Together, IRE is a promising approach to evoke CD8⁺ T cell immunity, which help prevent post-ablation HCC progression.

Comparative Analysis of Immunoactivation by Nanosecond Pulsed Electric Fields and PD-1 Blockade in Murine Hepatocellular Carcinoma

Nanosecond pulsed electric field (NsPEF) ablation effectively eliminates early-stage hepatocellular carcinoma (HCC) by local ablation and advanced HCC by inducing a remarkable and sustained host immune response. However, this approach is not sufficient to prevent cancer progression, and complementary approaches are necessary for effective immunotherapy. In this study, we evaluated the immunoactivating effects and mechanisms of action of nsPEF ablation and PD-1 blockade on an HCC orthotopic xenograft mouse model. Briefly, 24 C57BL-6J tumor-bearing mice were randomly assigned to three groups: nsPEF ablation group, anti-PD-1 administration group, and untreated control group. Tumor-infiltrating T, B, and NK cell levels and plasma concentrations of Th1 (IL-2, IFN-γ, and TNF-α), Th2 (IL-4, IL-5, IL-6, and IL-10), Th9 (IL-9), and Th17 (IL-17A, IL-17F, IL-21, and IL-22) cytokines were evaluated. Both nsPEF ablation and anti-PD-1 treatment induced immune cell infiltration in local tumors and modulated cytokine levels in the peripheral blood, with distinct changes in the two treatment groups. Based on these findings, both nsPEF ablation and PD-1 antibody administration can trigger a local and systemic immune response in a partially complementary manner, and nsPEF ablation should be considered along with PD-1 blockade for the treatment of HCC.

Recent progress in pulsed electric field ablation for liver cancer

The number of liver cancer patients is likely to continue to increase in the coming decades due to the aging of the population and changing risk factors. Traditional treatments cannot meet the needs of all patients. New treatment methods evolved from pulsed electric field ablation are expected to lead to breakthroughs in the treatment of liver cancer. This paper reviews the safety and efficacy of irreversible electroporation in clinical studies, the methods to detect and evaluate its ablation effect, the improvements in equipment and its antitumor effect, and animal and clinical trials on electrochemotherapy. We also summarize studies on the most novel nanosecond pulsed electric field ablation techniques in vitro and in vivo. These research results are certain to promote the progress of pulsed electric field in the treatment of liver cancer.

Dynamics of Cell Death After Conventional IRE and H-FIRE Treatments

High-frequency irreversible electroporation (H-FIRE) has emerged as an alternative to conventional irreversible electroporation (IRE) to overcome the issues associated with neuromuscular electrical stimulation that appear in IRE treatments. In H-FIRE, the monopolar pulses typically used in IRE are replaced with bursts of short bipolar pulses. Currently, very little is known regarding how the use of a different waveform affects the cell death dynamics and mechanisms. In this study, human pancreatic adenocarcinoma cells were treated with a typical IRE protocol and various H-FIRE schemes with the same energized time. Cell viability, membrane integrity and Caspase 3/7 activity were assessed at different times after the treatment. In both treatments, we identified two different death dynamics (immediate and delayed) and we quantified the electric field ranges that lead to each of them. While in the typical IRE protocol, the electric field range leading to a delayed cell death is very narrow, this range is wider in H-FIRE and can be increased by reducing the pulse length. Membrane integrity in cells suffering a delayed cell death shows a similar time evolution in all treatments, however, Caspase 3/7 expression was only observed in cells treated with H-FIRE.

Nanoparticle Conjugation of Ginsenoside Rg3 Inhibits Hepatocellular Carcinoma Development and Metastasis

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. The prognosis of HCC remains very poor; thus, an effective treatment remains urgent. Herein, a type of nanomedicine is developed by conjugating Fe@Fe₃ O₄ nanoparticles with ginsenoside Rg3 (NpRg3), which achieves an excellent coupling effect. In the dimethylnitrosamine-induced HCC model, NpRg3 application significantly prolongs the survival of HCC mice. Further research indicates that NpRg3 application significantly inhibits HCC development and eliminates HCC metastasis to the lung. Notably, NpRg3 application delays HCC-induced ileocecal morphology and gut microbial alterations more than 12 weeks during HCC progression. NpRg3 administration elevates the abundance of Bacteroidetes and Verrucomicrobia, but decreases Firmicutes. Twenty-nine predicted microbial gene functions are enriched, while seven gene functions are reduced after NpRg3 administration. Moreover, the metabolomics profile presents a significant progression during HCC development, but NpRg3 administration corrects tumor-dominant metabolomics. NpRg3 administration decreases 3-indolepropionic acid and urea, but elevates free fatty acids. Importantly, NpRg3 application remodels the unbalanced correlation networks between gut microbiota and metabolism during HCC therapy. In conclusion, nanoparticle conjugation of ginsenoside Rg3 inhibits HCC development and metastasis via the remodeling of unbalanced gut microbiota and metabolism in vivo, providing an antitumor therapy strategy.

Long Non-Coding RNA NEAT1 Promoted Hepatocellular Carcinoma Cell Proliferation and Reduced Apoptosis Through the Regulation of Let-7b-IGF-1R Axis

Background and aim

Long non-coding RNA nuclear-enriched abundant transcript 1 (NEAT1) is abnormally expressed in various human malignancies, including hepatocellular carcinoma (HCC). Let-7b is a miRNA with the effect of a tumor suppressor gene, and its expression level in various tumor tissues is lower than that in normal tissues. Studies have found that IGF-1R can be abnormally activated in the process of hepatocyte deterioration, and the expression level of IGF-1R in HCC is significantly up-regulated. The aim of this study was to investigate the functional mechanism of NEAT1/let-7b-IGF-1R axis in HCC.

Methods

The expressions of NEAT1 and microRNA (miR)-let-7b in HCC tissues and cell lines were quantified by quantitative real-time PCR (qRT-PCR). The effect of NEAT1 on tumor growth was observed in a mice model of transplanted hepatoma. The effects of down-regulation or up-regulation of NEAT1 expression in HCC cell lines were analysed from the perspectives of cell viability and apoptosis. The binding sites of NEAT1 and miR-let-7b were predicted by biological software. The expression of the miR-let-7b target molecules IGF-1R was detected by Western blotting.

Results

The results showed that the expressions of NEAT1 were significantly increased, while the expressions of miR-let-7b were decreased in the HCC tissues and cell lines. Additionally, it was found that the expressions of NEAT1 and miR-let-7b showed a negative correlation in HCC tissues. The mouse model experiments confirmed that the interference with NEAT1 expression inhibited the tumor growth. Meanwhile, the cell viability of HepG2/Huh7 cell lines was significantly decreased via the downregulation of NEAT1, whereas the corresponding rates of apoptosis were significantly increased. It was further proven that there was a certain negative regulatory mechanism between NEAT1 and miR-1et-7b, which was related to the expression of IGF-1R.

Conclusion

The over-expression of NEAT1 could promote the proliferation of HCC cells by inhibiting the expression of the miR-let-7b regulated by IGF-1R.