Targeting the crosstalk between cytokine-induced killer cells and myeloid-derived suppressor cells in hepatocellular carcinoma.

Cytokine-induced killer (CIK) cell-based immunotherapy is effective as an adjuvant therapy in early stage hepatocellular carcinoma (HCC) but lacks efficacy in advanced HCC. We aimed to investigate immune suppressor mechanisms in HCC, focusing on the role of myeloid-derived suppressor cells (MDSCs) in response to CIK therapy. MDSCs were quantified by flow cytometry and quantitative real-time PCR. Cytokines were detected by cytokine array. A lactate dehydrogenase cytotoxicity assay was performed in the presence or absence of MDSCs to study CIK function against HCC cells in vitro. An FDA-approved PDE5 inhibitor, tadalafil, was used to target MDSCs in vitro and in vivo. Two different murine HCC cell lines were tested in subcutaneous and orthotopic tumor models in C57BL/6 and BALB/c mice. The antitumor effects of human CIKs and MDSCs were also tested in vitro. Adoptive cell transfer of CIKs into tumor-bearing mice induced inflammatory mediators (e.g., CX3CL1, IL-13) in the tumor microenvironment and an increase of tumor-infiltrating MDSCs, leading to impaired antitumor activity in 2 different HCC models. MDSCs efficiently suppressed the cytotoxic activity of CIKs in vitro. In contrast, treatment with a PDE5 inhibitor reversed the MDSC suppressor function via ARG1 and iNOS blockade and systemic treatment with a PDE5 inhibitor prevented MDSC accumulation in the tumor microenvironment upon CIK cell therapy and increased its antitumor efficacy. Similar results were observed when human CIKs were tested in vitro in the presence of CD14+HLA-DR-/low MDSCs. Treatment of MDSCs with a PDE5 inhibitor suppressed MDSC suppressor function and enhanced CIK activity against human HCC cell lines in vitro. Our results suggest that targeting MDSCs is an efficient strategy to enhance the antitumor efficacy of CIKs for the treatment of patients with HCC. Cytokine-induced killer cells are a mixture of immune cells given to eliminate cancer cells. However, not all patients respond to this treatment. Herein, we show in 2 different liver cancer models that myeloid-derived suppressor cells are increased in response to cytokine-induced killer cell therapy. Targeting these myeloid-derived suppressor cells may provide an additional therapeutic benefit alongside cytokine-induced killer cell therapy.

Yu SJ ，Ma C ，Heinrich B ，Brown ZJ ，Sandhu M ，Zhang Q ，Fu Q ，Agdashian D ，Rosato U ，Korangy F ，Greten TF ... -  《-》

Dendritic Cell Immunotherapy Combined with Cytokine-Induced Killer Cells Effectively Suppresses Established Hepatocellular Carcinomas in Mice.

Jung NC ，Lee JH ，Choi HJ ，Hwang SU ，Song JY ，Seo HG ，Choi J ，Jung SY ，Han SG ，Lim DS ... -  《-》

Icaritin Induces Anti-tumor Immune Responses in Hepatocellular Carcinoma by Inhibiting Splenic Myeloid-Derived Suppressor Cell Generation.

Recent studies have demonstrated that splenic extramedullary hematopoiesis (EMH) is an important mechanism for the accumulation of myeloid-derived suppressor cells (MDSCs) in tumor tissues, and thus contributes to disease progression. Icaritin, a prenylflavonoid derivative from plants of the Epimedium genus, has been implicated as a novel immune-modulator that could prolong the survival of hepatocellular carcinoma (HCC) patients. However, it is unclear whether icaritin achieves its anti-tumor effects via the regulation of MDSCs generated by EMH in HCC. Here, we investigated the anti-tumor potential of icaritin and its mechanism of action in murine HCC. Icaritin suppressed tumor progression and significantly prolonged the survival of mice-bearing orthotopic and subcutaneous HCC tumors. Rather than exerting direct cytotoxic activity against tumor cells, icaritin significantly reduced the accumulation and activation of tumoral and splenic MDSCs, and increased the number and activity of cytotoxic T cells. Mechanistically, icaritin downregulates the tumor-associated splenic EMH, thereby reducing the generation and activation of MDSCs. The inhibitory effects of icaritin on human MDSCs in vitro were verified in short-term culture with cord-blood derived hematopoietic precursors. Furthermore, icaritin synergistically enhanced the therapeutic efficacy of immune checkpoint blockade therapy in HCC mice. These findings revealed that icaritin dampens tumoral immunosuppression to elicit anti-tumor immune responses by preventing MDSC generation via the attenuation of EMH. Thus, icaritin may serve as a novel adjuvant or even a stand-alone therapeutic agent for the effective treatment of HCC.

Tao H ，Liu M ，Wang Y ，Luo S ，Xu Y ，Ye B ，Zheng L ，Meng K ，Li L ... -  《Frontiers in Immunology》

Siwu decoction suppress myeloid-derived suppressor cells through tumour cells necroptosis to inhibit hepatocellular carcinoma.

Human hepatocellular carcinoma (HCC) acquired resistance to anti-cancer agents due to the presence of immunosuppressive tumour microenvironment (TME) established by the interaction between tumour cells and immune populations. New treatment targeting the interaction is urgently needed and clinically beneficial to patients with HCC. This study aims to explore the anti-tumour effect of a Traditional Chinese Medicine formula Siwu Decoction (SWD) and its potential mechanism. The chemical profile of SWD was determined by high-performance liquid chromatography coupled with mass spectrometry. In vitro and in vivo effects of SWD in regressing HCC were assessed. The role of myeloid-derived suppressor cells (MDSCs) in mediating SWD-induced HCC inhibition was determined by adoptive transfer assay. The regulation of SWD-induced interaction between HCC cells and MDSCs was also confirmed both in vitro and in vivo. SWD dose-dependent inhibited the HCC growth and lung metastasis in an orthotopic growth tumour in mice, without significant toxicity and adverse side effect. SWD induced necroptosis in HCC cells, but did not directly inhibit in vitro culture of MDSCs, instead, SWD-treated HCC cell culture supernatant suppressed MDSCs by inducing its cell apoptosis. The necroptotic response of HCC cells can also suppress the MDSCs population in the TME without reducing circulating MDSCs infiltration into the tumours. Adoptive transfer of MDSCs recovered tumour growth and lung metastasis of HCC in SWD-treated mice. In HCC cells, SWD induced a necroptotic response, and blockade of necroptotic response in HCC cells recovered the MDSCs population in vitro and in vivo, and restored tumour growth and lung metastasis in SWD-treated mice. A combination of SWD improves the anti-HCC efficacy of sorafenib without inducing adverse side effects. Albiflorin, the effective compound of SWD, its anti-HCC manner has been verified to be consistent with that of SWD. Our study observed for the first time that SWD can suppress HCC by regulating MDSCs through necroptosis of tumour cells in the TME. The main effective compound of SWD, albiflorin can be a potential adjuvant therapy in the clinical management of human HCC.

Feng Z ，Chan YT ，Lu Y ，Wu J ，Xing T ，Yuan H ，Feng Y ，Wang N ... -  《-》

DDR2/STAT3 Positive Feedback Loop Mediates the Immunosuppressive Microenvironment by Upregulating PD-L1 and Recruiting MDSCs in Oxaliplatin-Resistant HCC.

Transcriptome sequencing revealed high expression of DDR2 in oxaliplatin-resistant hepatocellular carcinoma (HCC). This study aimed to explore the role of DDR2 in oxaliplatin resistance and immune evasion in HCC. Oxaliplatin-resistant HCC cell lines were established. The interaction between DDR2 and STAT3 was investigated, along with the mechanisms involved in DDR2/STAT3-mediated PD-L1 upregulation and polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) accumulation both in vitro and in vivo. DDR2 was found to induce the phosphorylation of STAT3, leading to its nuclear translocation. Conversely, the activation of STAT3 enhanced DDR2 expression. A positive feedback loop involving DDR2/STAT3 was identified in oxaliplatin-resistant HCC, which was associated with PD-L1 upregulation and PMN-MDSCs accumulation. Knockdown of DDR2 and STAT3 sensitized oxaliplatin-resistant HCC cells to oxaliplatin and resulted in decreased PMN-MDSCs and increased CD8+ T cells in the tumor microenvironment. Enzyme-linked immunosorbent array and MDSC transwell migration assays indicated that oxaliplatin-resistant HCC cells recruited PMN-MDSCs through CCL20. Dual luciferase reporter assays demonstrated that STAT3 can directly enhance the transcription of PD-L1 and CCL20. Furthermore, treatment with a PD-L1 antibody in combination with CCL20 blockade had significant antitumor effects on oxaliplatin-resistant HCC. Our findings revealed a positive feedback mechanism involving DDR2 and STAT3 that mediates the immunosuppressive microenvironment and promotes oxaliplatin resistance and immune evasion via PD-L1 upregulation and PMN-MDSC recruitment. Targeting the DDR2/STAT3 pathway may be a promising therapeutic strategy to overcome immune escape and chemoresistance in HCC.

Liu W ，Zhang F ，Quan B ，Yao F ，Chen R ，Ren Z ，Dong L ，Yin X ... -  《Cellular and Molecular Gastroenterology and Hepatology》