Integration of Ethanol and the Immune Modulator Curcumin for Immunoablation of Hepatocellular Carcinoma.

PURPOSE: To investigate immuno-ethanol ablation using an ethanol and immune adjuvant formulation as a potent immunoablation approach that can achieve an enhanced anticancer effect in the treatment of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Ethanol concentration- and exposure time-dependent cellular responses were investigated. Curcumin was combined with ethanol as an immunoablation agent. Cellular uptake of curcumin, cancer cell killing, and inflammatory markers of ethanol-curcumin treatment were characterized. To evaluate the potential in vivo anticancer immunity of ethanol-curcumin treatment, each right and left lobe of rat liver was concurrently inoculated with N1S1 HCC cells and a mixture of treated N1S1 cells (ethanol only or ethanol-curcumin) in Sprague Dawley rats (each group: 5 rats; control: nontreated N1S1 cells). Tumor growth and immune response were characterized with 7T magnetic resonance (MR) imaging, flow cytometry analysis, and immunohistology. RESULTS: An optimized ethanol-curcumin (10% ethanol and 0.5% weight/volume (w/v) curcumin solution) treatment contributed to an enhanced cellular uptake of curcumin, increased cancer cell killing, and decreased inflammatory reaction. Ethanol-curcumin-treated N1S1 cell implantation in the rat liver demonstrated N1S1 HCC tumor rejection. The secondary tumor growth by nontreated N1S1 cell inoculation was significantly suppressed at the same time. Activated anticancer immunity was evidenced by significantly increased CD8+ T cell infiltration (3.5-fold) and CD8+-to-regulatory T cell ratio (4.5-fold) in the experimental group compared with those in the control group. CONCLUSIONS: Enhanced anticancer effect of immuno-ethanol ablation could be achieved with ethanol-curcumin agent. The results underscore the importance of optimized immunoablation therapeutic procedures for enhanced therapeutic outcomes.

Dendritic cell paucity in mismatch repair-proficient colorectal cancer liver metastases limits immune checkpoint blockade efficacy.

Liver metastasis is a major cause of mortality for patients with colorectal cancer (CRC). Mismatch repair-proficient (pMMR) CRCs make up about 95% of metastatic CRCs, and are unresponsive to immune checkpoint blockade (ICB) therapy. Here we show that mouse models of orthotopic pMMR CRC liver metastasis accurately recapitulate the inefficacy of ICB therapy in patients, whereas the same pMMR CRC tumors are sensitive to ICB therapy when grown subcutaneously. To reveal local, nonmalignant components that determine CRC sensitivity to treatment, we compared the microenvironments of pMMR CRC cells grown as liver metastases and subcutaneous tumors. We found a paucity of both activated T cells and dendritic cells in ICB-treated orthotopic liver metastases, when compared with their subcutaneous tumor counterparts. Furthermore, treatment with Feline McDonough sarcoma (FMS)-like tyrosine kinase 3 ligand (Flt3L) plus ICB therapy increased dendritic cell infiltration into pMMR CRC liver metastases and improved mouse survival. Lastly, we show that human CRC liver metastases and microsatellite stable (MSS) primary CRC have a similar paucity of T cells and dendritic cells. These studies indicate that orthotopic tumor models, but not subcutaneous models, should be used to guide human clinical trials. Our findings also posit dendritic cells as antitumor components that can increase the efficacy of immunotherapies against pMMR CRC.

A highly selective and potent CXCR4 antagonist for hepatocellular carcinoma treatment.

The CXC chemokine receptor type 4 (CXCR4) receptor and its ligand, CXCL12, are overexpressed in various cancers and mediate tumor progression and hypoxia-mediated resistance to cancer therapy. While CXCR4 antagonists have potential anticancer effects when combined with conventional anticancer drugs, their poor potency against CXCL12/CXCR4 downstream signaling pathways and systemic toxicity had precluded clinical application. Herein, BPRCX807, known as a safe, selective, and potent CXCR4 antagonist, has been designed and experimentally realized. In in vitro and in vivo hepatocellular carcinoma mouse models it can significantly suppress primary tumor growth, prevent distant metastasis/cell migration, reduce angiogenesis, and normalize the immunosuppressive tumor microenvironment by reducing tumor-associated macrophages (TAMs) infiltration, reprogramming TAMs toward an immunostimulatory phenotype and promoting cytotoxic T cell infiltration into tumor. Although BPRCX807 treatment alone prolongs overall survival as effectively as both marketed sorafenib and anti-PD-1, it could synergize with either of them in combination therapy to further extend life expectancy and suppress distant metastasis more significantly.

Transient Kupffer cell depletion and subsequent replacement by infiltrating monocyte-derived cells does not alter the induction or progression of hepatocellular carcinoma.

Due to a combination of rapid disease progression and the lack of curative treatment options, hepatocellular carcinoma (HCC) is one of the deadliest cancers worldwide. Infiltrated, monocyte-derived, tumor-associated macrophages are known to play a role in HCC pathogenesis, but the involvement of Kupffer cells (KCs) remains elusive. Here, we used the Clec4F-diphteria toxin receptor transgenic mouse model to specifically investigate the effect of KC depletion on HCC initiation, progression and neoplastic growth following liver resection. For this purpose, several HCC mouse models with varying underlying etiologies were used and partial hepatectomy was performed. Our results show that in HCC, developed on a fibrotic or non-alcoholic steatohepatitis background, depletion of embryonic KCs at the onset of HCC induction and the subsequent replacement by monocyte-derived KCs does not affect the tumor burden, tumor microenvironment or the phenotype of isolated KCs at end-stage disease. In non-chronic liver disease-associated diethylnitrosamine-induced HCC, ablation of Clec4F+ KCs did not alter tumor progression or neoplastic growth following liver resection. Our results show that temporal ablation of resident KCs does not impact HCC pathogenesis, neither in the induction phase nor in advanced disease, and indicate that bone marrow-derived KCs are able to swiftly repopulate the available KC niche and adopt their phenotype.

MicroRNA-15a/16-1 Prevents Hepatocellular Carcinoma by Disrupting the Communication Between Kupffer Cells and Regulatory T Cells.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) is characterized by intratumoral accumulation of regulatory T cells (Tregs), which suppresses antitumor immunity. This study was designed to investigate how microRNAs regulate immunosuppression in HCC. METHODS: FVB/NJ mice were hydrodynamically injected with AKT/Ras or c-Myc and Sleeping Beauty transposon to induce HCC. The Sleeping Beauty system was used to deliver microRNA-15a/16-1 into livers of mice. Flow cytometry and immunostaining were used to determine changes in the immune system. RESULTS: Hydrodynamic injection of AKT/Ras or c-Myc into mice resulted in hepatic enrichment of Tregs and reduced cytotoxic T cells (CTLs) and HCC development. HCC impaired microRNA-15a/16-1 biogenesis in Kupffer cells (KCs) of AKT/Ras and c-Myc mice. Hydrodynamic injection of microRNA-15a/16-1 fully prevented HCC in AKT/Ras and c-Myc mice, while 100% of control mice died of HCC. Therapeutically, microRNA-15a/16-1 promoted a regression of HCC in both mouse models, impaired hepatic enrichment of Tregs, and increased hepatic CTLs. Mechanistically, a significant increase was observed in serum C-C motif chemokine 22 (CCL22) and transcription of Ccl22 in KCs of AKT/Ras and c-Myc mice. MicroRNA-15a/16-1 prevented KCs from overproducing CCL22 by inhibiting nuclear factor-κB that activates transcription of Ccl22. By reducing CCL22 binding to C-C chemokine receptor type 4 on Tregs, microRNA-15a/16-1 impaired Treg chemotaxis. Disrupting the interaction between microRNA-15a/16-1 and nuclear factor-κB impaired the ability of microRNA-15a/16-1 to prevent hepatic Treg accumulation and HCC. Depletion of cluster of differentiation 8+ T cells and additional treatment of CCL22 recovered growth of HCC that was fully prevented by microRNA-15a/16. CONCLUSIONS: MicroRNA-15a/16-1 attenuates immunosuppression by disrupting CCL22-mediated communication between KCs and Tregs. MicroRNA-15a/16-1 represents a potential immunotherapy against HCC.

Myelocytomatosis-Protein Arginine N-Methyltransferase 5 Axis Defines the Tumorigenesis and Immune Response in Hepatocellular Carcinoma.

BACKGROUND AND AIMS: HCC is a leading cause of cancer-related deaths globally with poor outcome and limited therapeutic options. Although the myelocytomatosis (MYC) oncogene is frequently dysregulated in HCC, it is thought to be undruggable. Thus, the current study aimed to identify the critical downstream metabolic network of MYC and develop therapies for MYC-driven HCC. APPROACH AND RESULTS: Liver cancer was induced in mice with hepatocyte-specific disruption of Myc and control mice by administration of diethylnitrosamine. Liquid chromatography coupled with mass spectrometry-based metabolomic analyses revealed that urinary dimethylarginine, especially symmetric dimethylarginine (SDMA), was increased in the HCC mouse model in an MYC-dependent manner. Analyses of human samples demonstrated a similar induction of SDMA in the urines from patients with HCC. Mechanistically, Prmt5, encoding protein arginine N-methyltransferase 5, which catalyzes SDMA formation from arginine, was highly induced in HCC and identified as a direct MYC target gene. Moreover, GSK3326595, a PRMT5 inhibitor, suppressed the growth of liver tumors in human MYC-overexpressing transgenic mice that spontaneously develop HCC. Inhibition of PRMT5 exhibited antiproliferative activity through up-regulation of the tumor suppressor gene Cdkn1b/p27, encoding cyclin-dependent kinase inhibitor 1B. In addition, GSK3326595 induced lymphocyte infiltration and major histocompatibility complex class II expression, which might contribute to the enhanced antitumor immune response. Combination of GSK3326595 with anti-programed cell death protein 1 (PD-1) immune checkpoint therapy (ICT) improved therapeutic efficacy in HCC. CONCLUSIONS: This study reveals that PRMT5 is an epigenetic executer of MYC, leading to repression of the transcriptional regulation of downstream genes that promote hepatocellular carcinogenesis, highlights a mechanism-based therapeutic strategy for MYC-driven HCC by PRMT5 inhibition through synergistically suppressed proliferation and enhanced antitumor immunity, and finally provides an opportunity to mitigate the resistance of "immune-cold" tumor to ICT.

Mild Magnetic Hyperthermia-Activated Innate Immunity for Liver Cancer Therapy.

Magnetic hyperthermia therapy (MHT) is noninvasive and features excellent tissue penetration for deep-seated tumors, but unfortunately, it suffers the low therapeutic efficacy due to the limited magneto-thermal efficiency and insufficient intratumor accumulation of conventional intravenous-injected magnetic nanoparticles, which are actually mostly sequestered by the mononuclear phagocyte system, especially the liver. Such a disadvantageous characteristic of preferential liver uptake is here exploited, for the first time as far as we know, to treat orthotopic liver cancer by mild MHT using specially designed composite magnetic nanoparticles. A kind of core-shell-structured and Zn2+-doped Zn-CoFe2O4@Zn-MnFe2O4 superparamagnetic nanoparticles (ZCMF) has been synthesized which exhibits excellent and highly controllable magnetic hyperthermia performance owing to an exchange-coupled magnetism between the core and shell, and Zn2+ doping. The controllable mild MHT at 43-44 °C based on ZCMF demonstrates almost complete inhibition of liver cancer cell proliferation and tumor growth, which is associated with the suppression of heat shock protein 70 (HSP70) expression. More importantly, the mild MHT-treated liver cancer cells are capable of activating natural killer (NK) cells by dramatically upregulating the expression of UL16-binding proteins (ULBPs), ligands of natural killer group 2 member D (NKG2D). As a result, the growth of both xenograft tumors and orthotopic liver tumors were almost completely suppressed under mild MHT via induced NK-cell-related antitumor immunity in vivo. This work not only evidences the great potential of mild MHT but also reveals the underlying immunity activation mechanism in liver cancer treatment by mild MHT.

C-X-C chemokine receptor 2 (Cxcr2) promotes hepatocellular carcinoma immune evasion via regulating programmed death-ligand 1 (PD-L1).

Strategies to sensitize hepatocellular carcinomas (HCC) to programmed death-1 (PD1)/programmed death-ligand 1 (PD-L1) inhibitor therapies are important in improving the survival of HCC patients. The aim of the study was to characterize C-X-C chemokine receptor 2 (Cxcr2) as a therapeutic target in HCC and evaluate the effects of Cxcr2 suppression in sensitizing HCC to PD1/PD-L1 inhibitor therapies. To this end, we constructed a Cxcr2-knockout HCC cell line (Hepa1-6 KO) using the CRISPR-Cas9 approach and assessed the tumor growth rate and survival of mice after subcutaneously inoculating Hepa1-6 KO cells in mice. We show that Cxcr2 knockdown does not dramatically inhibit tumor growth and improve mouse survival. In tumor xenografts, the proportion of T cells is not affected but the ratio of M1/M2 macrophage is greatly increased. Cxcr2 knockdown does not alter cell viability but macrophages co-cultured with Hepa1-6 KO cells are shifted to M1 phenotypes compared to WT cells. Hepa-1-6 KO cells exhibit lower levels of PD-L1 expression. c-Myc is suppressed in Hepa1-6 KO cells, which contributes to PD-L1 downregulation. Knockdown of Cxcr2 decreases PD-L1 levels and consequently promotes the shift of macrophages to the M1 phenotype, which is mediated by downregulating c-Myc. In summary, Cxcr2 is a potential target for suppressing immune escape in HCC.

Tumor-associated neutrophils suppress pro-tumoral IL-17+ γδ T cells through induction of oxidative stress.

Interleukin 17 (IL-17)-producing γδ T cells (γδ17 T cells) have been recently found to promote tumor growth and metastasis formation. How such γδ17 T-cell responses may be regulated in the tumor microenvironment remains, however, largely unknown. Here, we report that tumor-associated neutrophils can display an overt antitumor role by strongly suppressing γδ17 T cells. Tumor-associated neutrophils inhibited the proliferation of murine CD27- Vγ6+ γδ17 T cells via induction of oxidative stress, thereby preventing them from constituting the major source of pro-tumoral IL-17 in the tumor microenvironment. Mechanistically, we found that low expression of the antioxidant glutathione in CD27- γδ17 T cells renders them particularly susceptible to neutrophil-derived reactive oxygen species (ROS). Consistently, superoxide deficiency, or the administration of a glutathione precursor, rescued CD27- Vγ6+ γδ17 T-cell proliferation in vivo. Moreover, human Vδ1+ γδ T cells, which contain most γδ17 T cells found in cancer patients, also displayed low glutathione levels and were potently inhibited by ROS. This work thus identifies an unanticipated, immunosuppressive yet antitumoral, neutrophil/ROS/γδ17 T-cell axis in the tumor microenvironment.

Preferential Expression of Programmed Death Ligand 1 Protein in Tumor-Associated Macrophages and Its Potential Role in Immunotherapy for Hepatocellular Carcinoma.

A predictive biomarker of immune checkpoint inhibitor (ICI)-based treatments in hepatocellular carcinoma (HCC) has not been clearly demonstrated. In this study, we focused on the infiltration and programmed death ligand 1 (PD-L1) expression of tumor-associated macrophages (TAMs) in the tumor microenvironment of HCC. Immunohistochemistry demonstrated that PD-L1 was preferentially expressed on CD68+ macrophages in the tumor microenvironment of HCC, suggestive of its expression in TAMs rather than in T cells or tumor cells (P < 0.05). A co-culture experiment using activated T cells and M2 macrophages confirmed a significant increase in T cell functionality after the pretreatment of M2 macrophages with anti-PD-L1. Syngeneic mouse model experiments demonstrated that TAMs expressed PD-L1 and tumors treated with anti-PD-L1 showed smaller diameters than those treated with IgG. In these mice, anti-PD-L1 treatment increased activation markers in intratumoral CD8+ T cells and reduced the size of the TAM population. Regarding nivolumab-treated patients, three of eight patients responded to the anti-PD-1 treatment. The percentage of Ki-67-positive CD4+ and CD8+ T cells was higher in responders than non-responders after nivolumab. Overall, PD-L1 expression on TAMs may be targeted by immune-based HCC treatment, and ICI treatment results in the reinvigoration of exhausted CD8+ T cells in HCC.

Targeting monocyte-intrinsic enhancer reprogramming improves immunotherapy efficacy in hepatocellular carcinoma.

OBJECTIVE: Hepatocellular carcinoma (HCC), mostly developed in fibrotic/cirrhotic liver, exhibits relatively low responsiveness to immune checkpoint blockade (ICB) therapy. As myeloid-derived suppressor cell (MDSC) is pivotal for immunosuppression, we investigated its role and regulation in the fibrotic microenvironment with an aim of developing mechanism-based combination immunotherapy. DESIGN: Functional significance of MDSCs was evaluated by flow cytometry using two orthotopic HCC models in fibrotic liver setting via carbon tetrachloride or high-fat high-carbohydrate diet and verified by clinical specimens. Mechanistic studies were conducted in human hepatic stellate cell (HSC)-peripheral blood mononuclear cell culture systems and fibrotic-HCC patient-derived MDSCs. The efficacy of single or combined therapy with anti-programmed death-1-ligand-1 (anti-PD-L1) and a clinically trialled BET bromodomain inhibitor i-BET762 was determined. RESULTS: Accumulation of monocytic MDSCs (M-MDSCs), but not polymorphonuclear MDSCs, in fibrotic livers significantly correlated with reduced tumour-infiltrating lymphocytes (TILs) and increased tumorigenicity in both mouse models. In human HCCs, the tumour-surrounding fibrotic livers were markedly enriched with M-MDSC, with its surrogate marker CD33 significantly associated with aggressive tumour phenotypes and poor survival rates. Mechanistically, activated HSCs induced monocyte-intrinsic p38 MAPK signalling to trigger enhancer reprogramming for M-MDSC development and immunosuppression. Treatment with p38 MAPK inhibitor abrogated HSC-M-MDSC crosstalk to prevent HCC growth. Concomitant with patient-derived M-MDSC suppression by i-BET762, combined treatment with anti-PD-L1 synergistically enhanced TILs, resulting in tumour eradication and prolonged survival in the fibrotic-HCC mouse model. CONCLUSION: Our results signify how non-tumour-intrinsic properties in the desmoplastic microenvironment can be exploited to reinstate immunosurveillance, providing readily translatable combination strategies to empower HCC immunotherapy.

Molecular MRI of the Immuno-Metabolic Interplay in a Rabbit Liver Tumor Model: A Biomarker for Resistance Mechanisms in Tumor-targeted Therapy?

Background The immuno-metabolic interplay has gained interest for determining and targeting immunosuppressive tumor micro-environments that remain a barrier to current immuno-oncologic therapies in hepatocellular carcinoma. Purpose To develop molecular MRI tools to reveal resistance mechanisms to immuno-oncologic therapies caused by the immuno-metabolic interplay in a translational liver cancer model. Materials and Methods A total of 21 VX2 liver tumor-bearing New Zealand white rabbits were used between October 2018 and February 2020. Rabbits were divided into three groups. Group A (n = 3) underwent intra-arterial infusion of gadolinium 160 (160Gd)-labeled anti-human leukocyte antigen-DR isotope (HLA-DR) antibodies to detect antigen-presenting immune cells. Group B (n = 3) received rhodamine-conjugated superparamagnetic iron oxide nanoparticles (SPIONs) intravenously to detect macrophages. These six rabbits underwent 3-T MRI, including T1- and T2-weighted imaging, before and 24 hours after contrast material administration. Group C (n = 15) underwent extracellular pH mapping with use of MR spectroscopy. Of those 15 rabbits, six underwent conventional transarterial chemoembolization (TACE), four underwent conventional TACE with extracellular pH-buffering bicarbonate, and five served as untreated controls. MRI signal intensity distribution was validated by using immunohistochemistry staining of HLA-DR and CD11b, Prussian blue iron staining, fluorescence microscopy of rhodamine, and imaging mass cytometry (IMC) of gadolinium. Statistical analysis included Mann-Whitney U and Kruskal-Wallis tests. Results T1-weighted MRI with 160Gd-labeled antibodies revealed localized peritumoral ring enhancement, which corresponded to gadolinium distribution detected with IMC. T2-weighted MRI with SPIONs showed curvilinear signal intensity representing selective peritumoral deposition in macrophages. Extracellular pH-specific MR spectroscopy of untreated liver tumors showed acidosis (mean extracellular pH, 6.78 ± 0.09) compared with liver parenchyma (mean extracellular pH, 7.18 ± 0.03) (P = .008) and peritumoral immune cell exclusion. Normalization of tumor extracellular pH (mean, 6.96 ± 0.05; P = .02) using bicarbonate during TACE increased peri- and intratumoral immune cell infiltration (P = .002). Conclusion MRI in a rabbit liver tumor model was used to visualize resistance mechanisms mediated by the immuno-metabolic interplay that inform susceptibility and response to immuno-oncologic therapies, providing a therapeutic strategy to restore immune permissiveness in liver cancer. © RSNA, 2020 Online supplemental material is available for this article.

Antitumor Immunity Augmented by Combining Radiofrequency Ablation with Anti-CTLA-4 Therapy in a Subcutaneous Murine Hepatoma Model.

PURPOSE: To evaluate whether antitumor immunity is enhanced by combining radiofrequency (RF) ablation and anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) therapy and to evaluate its effect on untreated tumors. MATERIALS AND METHODS: First, 40 mice with tumors established in the bilateral flanks were randomly divided into 4 groups: the control group, the RF ablation-alone group, the anti-CTLA-4-alone group, and the RF ablation + anti-CTLA-4 group. In each group, 8 mice were used for untreated tumor evaluation and survival observation, and another 2 mice were killed for histopathologic study. Then, a rechallenge test was performed in another 32 mice to determine whether systemic antitumor immunity was established. RESULTS: Although the volume of the untreated tumors continued to increase until the end of the observation in all groups, tumor growth rates in the RF ablation + anti-CTLA-4 group were significantly smaller than tumor growth rates in the other 3 groups (all P < .05). The overall survival time of mice in the RF ablation + anti-CTLA-4 group was significantly longer than that of mice in the other 3 groups (all P < .05). Histopathologic studies of the untreated tumors showed more CD4-and CD8+ lymphocyte infiltration in mice from the RF ablation + anti-CTLA-4 group than in mice from the other 3 groups (all P < .05). After a tumor rechallenge, tumor rejection was apparent in 75% of the mice in the RF ablation + anti-CTLA-4 group, in 25% of the mice in the RF ablation group, and in 0% of the mice in the control and anti-CTLA-4 groups. CONCLUSIONS: This study demonstrated that RF ablation-induced systemic antitumor immunity was enhanced by the combined use of anti-CTLA-4 therapy in a multi-subcutaneous murine hepatoma model.

MiR-15a/16-1 deficiency induces IL-10-producing CD19+ TIM-1+ cells in tumor microenvironment.

IL-10-producing B cells (B10) are associated with autoimmune diseases, infection and tumours. MiR-15a/16 as a tumour-suppressive gene is down-regulated in several tumours, such as chronic lymphocytic leukaemia, pituitary adenomas and prostate carcinoma. Here, increased frequency of IL-10-producing CD19+ Tim-1+ cells was seen in both aged miR-15a/16-/- mice (15-18 months) with the onset of B cell leukaemia and young knockout mice (8-12 weeks) transplanted with hepatic cancer cells. CD19+ Tim-1+ cells down-regulated the function of effector CD4+ CD25low T cells ex vivo dependent on IL-10 production, and adoptive transfer of CD19+ Tim-1+ cells promoted tumour growth in mice. IL-10 production by CD19+ Tim-1+ cells was involved with the STAT3 activation. Bioinformatics analysis shows that miR-16 targets the 3'-untranslating region (3'-UTR) of STAT3 mRNA. Overexpression of miR-16 in CD19+ Tim-1+ cells inhibited STAT3 transcription and its protein expression. Thus, the loss of miR-15a/16 promoted induction of regulatory CD19+ Tim-1+ cells in tumour microenvironment. These results confirmed that miR-15a/16 could be used in tumour therapy due to its inhibition of tumour and regulatory B cells.

Sirtuin2 enhances the tumoricidal function of liver natural killer cells in a mouse hepatocellular carcinoma model.

Hepatocellular carcinoma (HCC) is the third most lethal cancer in the world. Natural killer (NK) cell-mediated immunity is crucial for tumor surveillance and therapy. Characterization of the regulatory mechanisms of NK cell function is important for developing novel immunotherapies against HCC. In this study, we used a chemical-induced mouse HCC model to identify the upregulation of Sirtuin2 (SIRT2) in liver NK cells. In particular, SIRT2 was predominantly expressed in liver CD94+ NK cells. The HCC liver microenvironment induced SIRT2 expression in NK cells. In addition, overexpression of exogenous SIRT2 significantly upregulated the production of cytokines and cytotoxic mediators in activated NK cells. Consistently, SIRT2-overexpressing NK cells showed a stronger tumoricidal effect on hepatoma cells. Moreover, SIRT2 remarkably promoted the phosphorylation of Extracellular-signal-regulated kinase 1/2 (Erk1/2) and p38 Mitogen-activated protein kinases (MAPK) in activated NK cells. SIRT2 knockdown in liver CD94+ NK cells impaired their cytotoxic effect on hepatoma cells. Our study indicates that SIRT2 enhances the tumoricidal activity of liver NK cells in HCC.

Pten Haplodeficiency Accelerates Liver Tumor Growth in miR-122a-Null Mice via Expansion of Periportal Hepatocyte-Like Cells.

This study aimed to shed light on the molecular and cellular mechanisms responsible for initiation and progression of liver malignancies by examining the role of phosphatase and tensin homolog on chromosome 10 (Pten) in liver tumor progression in miR-122a (Mir122a)-null mice. We generated and monitored liver tumor initiation in Mir122a-null Pten heterozygous (Mir122a-/-;Pten+/- and Mir122a-/-;Alb-Cre;Ptenfx/+) mice and compared the results with those in Mir122a-/- mice. Both Mir122a-/-;Pten+/- and Mir122a-/-;Alb-Cre;Ptenfx/+ mice developed visible liver tumor nodules at 6 months of age. In premalignant livers of Mir122a-/-;Pten+/- mice, decreased PTEN and increased phosphorylated AKT were specifically observed in periportal cells, associated with inflammatory and fibrotic microenvironments. Furthermore, IL-1ß and tumor necrosis factor-α levels significantly increased in Mir122a-/-;Pten+/- premalignant livers at 6 months of age. Oval cells expressing A6, epithelial cell adhesion molecule, keratin (K) 8, K19, and SRY (sex determining region Y)-box 9 (SOX9) were present in both Mir122a-/- and Mir122a-/-;Pten+/- livers. Interestingly, a hybrid hepatocyte-like population with intermediate levels of K8, HNF4α, and SOX9 was located proximally to the oval cells in Mir122a-/-;Pten+/- livers. Lineage-tracing experiments revealed that these intermediate levels of K8 hepatocyte-like cells may be the cells of origin for Mir122a-/-;Pten+/- liver tumors. These findings suggest that inflammatory microenvironments in the periportal area of Mir122a-null mice may locally cause Pten down-regulation and expand tumor-initiating cells, causing hepatocellular carcinoma.

Therapeutic Effect of Irreversible Electroporation in Combination with Poly-ICLC Adjuvant in Preclinical Models of Hepatocellular Carcinoma.

PURPOSE: To evaluate the therapeutic efficacy of irreversible electroporation (IRE) combined with the intratumoral injection of the immunogenic adjuvant poly-ICLC (polyinosinic-polycytidylic acid and poly-L-lysine, a dsRNA analog mimicking viral RNA) inmediately before IRE. MATERIALS AND METHODS: Mice and rabbits bearing hepatocellular carcinoma tumors (Hepa.129 and VX2 tumor models, respectively) were treated with IRE (2 pulses of 2500V), with poly-ICLC, or with IRE + poly-ICLC combination therapy. Tumor growth in mice was monitored using a digital caliper and by computed tomography in rabbits. RESULTS: Intratumoral administration of poly-ICLC immediately before IRE elicited shrinkage of Hepa.129 cell-derived tumors in 70% of mice, compared to 30% and 26% by poly-ICLC or IRE alone, respectively (P = .0004). This combined therapy induced the shrinkage of VX-2-based hepatocellular carcinoma tumors in 40% of rabbits, whereas no response was achieved by either individual treatment (P = .045). The combined therapy activated a systemic antitumor response able to inhibit the growth of other untreated tumors. CONCLUSIONS: IRE treatment, immediately preceded by the intratumoral administration of an immunogenic adjuvant such as poly-ICLC, might enhance the antitumor effect of the IRE procedure. This combination might facilitate the induction of a long-term systemic response to prevent tumor relapses and the appearance of metastases.

Hepatic Stellate Cells Enhance Liver Cancer Progression by Inducing Myeloid-Derived Suppressor Cells through Interleukin-6 Signaling.

The tumor microenvironment, which consists of fibroblasts, smooth muscle cells, endothelial cells, immune cells, epithelial cells, and extracellular matrices, plays a crucial role in tumor progression. Hepatic stellate cells (HSCs), a class of unique liver stromal cells, participate in immunomodulatory activities by inducing the apoptosis of effector T-cells, generation of regulatory T-cells, and development of myeloid-derived suppressor cells (MDSCs) to achieve long-term survival of islet allografts. This study provides in vitro and in vivo evidences that HSCs induce the generation of MDSCs to promote hepatocellular carcinoma (HCC) progression through interleukin (IL)-6 secretion. HSC-induced MDSCs highly expressed inducible nitric oxide synthase (iNOS) and arginase 1 mRNA and presented potent inhibitory T-cell immune responses in the tumor environment. Wild-type HSC-induced MDSCs expressed lower levels of CD40, CD86, and MHC II, and a higher level of B7-H1 surface molecules, as well as increased the production of iNOS and arginase I compared with MDSCs induced by IL-6-deficient HSCs in vitro. A murine-transplanted model of the liver tumor showed that HCCs cotransplanted with HSCs could significantly enhance the tumor area and detect more MDSCs compared with HCCs alone or HCCs cotransplanted with HSCs lacking IL-6. In conclusion, the results indicated that MDSCs are induced mainly by HSCs through IL-6 signaling and produce inhibitory enzymes to reduce T-cell immunity and then promote HCC progression within the tumor microenvironment. Therapies targeting the pathway involved in MDSC production or its immune-modulating pathways can serve as an alternative immunotherapy for HCC.

Targeting tumor-infiltrating Ly6G+ myeloid cells improves sorafenib efficacy in mouse orthotopic hepatocellular carcinoma.

Sorafenib, a multikinase inhibitor with antiangiogenic activity, is an approved therapy for hepatocellular carcinoma (HCC). It is unclear whether the proinflammatory and immunosuppressive mechanisms may limit the therapeutic efficacy of sorafenib in HCC. We used a syngeneic mouse liver cancer cell line to establish orthotopic liver or subcutaneous tumors to study how proinflammatory and immunosuppressive mechanisms impact on the efficacy of sorafenib. We found sorafenib exhibited a potent therapeutic effect in subcutaneous tumors, but a less potent effect in orthotopic liver tumors. The protein levels of interleukin-6 (IL-6) and vascular endothelial growth factor A (VEGF-A) were persistently elevated in orthotopic liver tumors, but not in subcutaneous tumors, treated with sorafenib. Likewise, the tumor-infiltrating Ly6G+ myeloid-derived suppressor cells (MDSCs) and immune suppressors were increased in orthotopic liver tumors, not in subcutaneous tumors, treated with sorafenib. The tumor-infiltrating Ly6G+ MDSCs of sorafenib-treated orthotopic liver tumors significantly induced IL-10 and TGF-ß expressing CD4+ T cells, and downregulated the cytotoxic activity of CD8+ T cells. IL-6, but not VEGF-A, protected Ly6G+ MDSCs from sorafenib-induced cell death in vitro. The combination of anti-Ly6G antibody or anti-IL-6 antibody with sorafenib significantly reduced the cell proportion of Ly6G+ MDSCs in orthotopic liver tumors, enhanced the T cells proliferation and improved the therapeutic effect of sorafenib synergistically. Modulating tumor microenvironment through targeting tumor-infiltrating Ly6G+ MDSCs represents a potential strategy to improve the anti-HCC efficacy of sorafenib.

Targeting of tumour-infiltrating macrophages via CCL2/CCR2 signalling as a therapeutic strategy against hepatocellular carcinoma.

OBJECTIVE: Hepatocellular carcinoma (HCC) is an aggressive malignancy with limited effective treatment options. An alternative strategy is to target cells, such as tumour-infiltrating macrophages, in the HCC tumour microenvironment. The CCL2/CCR2 axis is required for recruitment of monocytes/macrophages and is implicated in various aspects of liver pathology, including HCC. We investigated the feasibility of CCL2/CCR2 as a therapeutic target against HCC. DESIGN: CCL2 expression was analysed in two independent HCC cohorts. Growth of three murine HCC cells was evaluated in an orthotopic model, a postsurgical recurrence model and a subcutaneous model in mice after blocking CCL2/CCR2 axis by a novel CCR2 antagonist or knocking out of host CCR2. In vivo macrophage or T cell depletion and in vitro cell coculture were further conducted to investigate CCL2/CCR2-mediated crosstalk between tumour-associated macrophages (TAMs) and tumour cells. RESULT: CCL2 is overexpressed in human liver cancers and is prognostic for patients with HCC. Blockade of CCL2/CCR2 signalling with knockout of CCR2 or with a CCR2 antagonist inhibits malignant growth and metastasis, reduces postsurgical recurrence, and enhances survival. Further, therapeutic blocking of the CCL2/CCR2 axis inhibits the recruitment of inflammatory monocytes, infiltration and M2-polarisation of TAMs, resulting in reversal of the immunosuppression status of the tumour microenvironment and activation of an antitumorous CD8+ T cell response. CONCLUSIONS: In patients with liver cancer, CCL2 is highly expressed and is a prognostic factor. Blockade of CCL2/CCR2 signalling suppresses murine liver tumour growth via activating T cell antitumour immune response. The results demonstrate the translational potential of CCL2/CCR2 blockade for treatment of HCCs.