RESUMEN
BACKGROUND: Hypoxia is a hallmark of cancer, and is closely intertwined with tumor immune evasion. Circular RNAs (circRNAs) have been implicated in tumor response to immune checkpoint blockades. However, hypoxia-associated circRNAs that orchestrate the association between hypoxia and response to immunotherapy remain poorly understood. Here, we aimed to determine the roles of hypoxia-associated circRNAs in immune escape of hepatocellular carcinoma (HCC) cells. METHODS: Differentially expressed hypoxia-associated circRNAs were determined using high-throughput sequencing technology. HCC patients treated with PD-1 blockade were enrolled to assess the clinical significance of circPRDM4. RT-qPCR, western blotting, flow cytometry, T cell-mediated tumor cell killing assay, and enzyme linked immunosorbent assay were used to investigate the roles of circPRDM4 in immune escape of HCC cells in vitro. Patient-derived xenograft mouse models and adoptive human tumor infiltrating lymphocyte-CD8+ T cell transfer were adopted to evaluate the effects of circPRDM4 in vivo. RNA pull-down, mass spectrometry, RNA immunoprecipitation, chromatin immunoprecipitation, chromatin isolation by RNA purification, dual-luciferase reporter assays, dot blotting, DNA in situ hybridization, and immunoprecipitation were utilized to examine the interaction between circPRDM4, HIF-1α, and CD274 promoter. RESULTS: We identified circPRDM4 as a hypoxia-associated circRNA in HCC. circPRDM4 was upregulated in responders to PD-1 blockade and associated with therapeutic efficacy. In vitro and in vivo experiments showed that circPRDM4 induced PD-L1 expression and promoted CD8+ T cell-mediated immune escape under hypoxic conditions. Mechanistically, circPRDM4 acted as a scaffold to recruit HIF-1α onto CD274 promoter, and cemented their interaction, ultimately promoting the HIF-1α-mediated transactivation of PD-L1. CONCLUSIONS: These findings illustrated that circPRDM4 promoted immune escape of HCC cells by facilitating the recruitment of HIF-1α onto the promoter of CD274 under hypoxia, thereby inhibiting CD8+ T cell infiltration in the tumor microenvironment. This work may provide a novel prognostic biomarker and therapeutic candidate for HCC immunotherapy.
RESUMEN
Interleukin (IL)-20 is a member of the IL-10 family of cytokines, which has been reported to participate in autoimmune inflammatory diseases. However, the potential role of IL-20 in hepatocellular carcinoma (HCC) progression has not yet been investigated. In the present study, it was observed that IL-20 mRNA and protein levels were markedly increased in the HCC tissues examined via reverse transcription-quantitative polymerase chain reaction and immunohistochemical staining. In addition, IL-20 expression was significantly associated with tumor size, metastasis, TNM stage and poor prognosis in patients with HCC. Mouse recombinant IL-20 (mIL-20) enhanced liver cancer cell proliferation, migration and invasion in vitro, while the anti-IL-20 monoclonal antibody (mAb) attenuated the effect of mIL-20, inhibiting cancer cell migration and invasion in vitro and suppressing cell growth in vitro and in vivo. This was detected by Cell Counting Kit-8, colony formation, Transwell assays and a xenograft tumor nude mouse model. Western blotting revealed that IL-20 promoted HCC progression through inducing transforming growth factor-ß and matrix metalloproteinase 9 expression and enhancing the phosphorylation of Jun N-terminal kinase and signal transducer and activator of transcription 3. The results of the present study indicated that IL-20 promotes HCC development. In addition, anti-IL-20 mAb may attenuate the effect of IL-20 and suppress liver tumorigenesis in vitro and in vivo, indicating that anti-IL-20 mAbs may potentially serve as effective therapeutic agents for HCC.
RESUMEN
In the present work, we undertook the complete mitochondrial genome sequencing of an important liver cancer model inbred rat strain for the first time. The total length of the mitogenome was 16,308 bp. It harbored 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 1 non-coding control region (D-loop region). The mutation events were also reported.
