Cancer cell-derived exosomal circUHRF1 induces natural killer cell exhaustion and may cause resistance to anti-PD1 therapy in hepatocellular carcinoma

Abstract

Objective: Natural killer (NK) cells play a critical role in the innate antitumor immune response. Recently, NK cell dysfunction has been verified in various malignant tumors, including hepatocellular carcinoma (HCC). However, the molecular biological mechanisms of NK cell dysfunction in human HCC are still obscure. Methods:The expression of circular ubiquitin-like with PHD and ring finger domain 1 RNA (circUHRF1) in HCC tissues, exosomes, and cell lines was detected by qRT-PCR. Exosomes were isolated from the culture medium of HCC cells and plasma of HCC patients using an ultracentrifugation method and the ExoQuick Exosome Precipitation Solution kit and then characterized by transmission electronic microscopy, NanoSight and western blotting. The role of circUHRF1 in NK cell dysfunction was assessed by ELISA. In vivo circRNA precipitation, RNA immunoprecipitation, and luciferase reporter assays were performed to explore the molecular mechanisms of circUHRF1 in NK cells. In a retrospective study, the clinical characteristics and prognostic significance of circUHRF1 were determined in HCC tissues.Results: Here, we report that the expression of circUHRF1 is higher in human HCC tissues than in matched adjacent nontumor tissues. Increased levels of circUHRF1 indicate poor clinical prognosis and NK cell dysfunction in patients with HCC. In HCC patient plasma, circUHRF1 is predominantly secreted by HCC cells in an exosomal manner, and circUHRF1 inhibits NK cell-derived IFN-γ and TNF-α secretion. A high level of plasma exosomal circUHRF1 is associated with a decreased NK cell proportion and decreased NK cell tumor infiltration. Moreover, circUHRF1 inhibits NK cell function by upregulating the expression of TIM-3 via degradation of miR-449c-5p. Finally, we show that circUHRF1 may drive resistance to anti-PD1 immunotherapy in HCC patients.Conclusions: Exosomal circUHRF1 is predominantly secreted by HCC cells and contributes to immunosuppression by inducing NK cell dysfunction in HCC. CircUHRF1 may drive resistance to anti-PD1 immunotherapy, providing a potential therapeutic strategy for patients with HCC.

Exosome-derived ENO1 regulates integrin α6β4 expression and promotes hepatocellular carcinoma growth and metastasis

“…On the other hand, some proteins in TEXs can partially reflect the dysregulated protein profile in tumor cells, reveal the characteristics of tumor cells, and provide a new direction for the diagnosis or prognostic evaluation of tumors 12 , 13 . Numerous recent studies have confirmed that exosomes play a vital role in the progression of HCC 14 – 18 .…”

Isolation and characterization of exosomes for cancer research

“…The lncRNA ARSR carried in exosomes shed by tumor cells can induce a phenotypic transformation from sunitinib sensitivity to resistance [ 193 ]. Furthermore, exosomal circUHRF1 enhances HCC resistance to anti-PD1 therapy via increased expression of T cell immunoglobulin and mucin domain 3 (TIM-3), a negative immunomodulatory receptor that interacts with tumor ligands [ 194 ].…”

The Roles of circRNAs in Liver Cancer Immunity

“…High level of plasma exosomal circUHRF1 was associated with a decreased proportion of NK cells and decreased NK cells tumor infiltration. In addition, circUHRF1 up-regulated the expression of T cell immunoglobulin and mucin domain 3 (TIM-3) by degrading miR-449c-5p, thereby inhibiting the function of NK cells ( 173 ) ( Figure 4 ). TIM-3 plays an important role in cell immunity, it was expressed in NK cells and affects cellular immune responses ( 174 ).…”