Background and Aims: Type 3 innate lymphoid cells (ILC3s) are essential for host defense against infection and tissue homeostasis. However, their role in the development of HCC has not been adequately confirmed. In this study, we investigated the immunomodulatory role of short‐chain fatty acids (SCFAs) derived from intestinal microbiota in ILC3 regulation. Approach and Results: We report that Lactobacillus reuteri was markedly reduced in the gut microbiota of mice with HCC, accompanied by decreased SCFA levels, especially acetate. Additionally, transplantation of fecal bacteria from wild‐type mice or L. reuteri could promote an anticancer effect, elevate acetate levels, and reduce IL‐17A secretion in mice with HCC. Mechanistically, acetate reduced the production of IL‐17A in hepatic ILC3s by inhibiting histone deacetylase activity, increasing the acetylation of SRY (sex‐determining region Y)‐box transcription factor 13 (Sox13) at site K30, and decreasing expression of Sox13. Moreover, the combination of acetate with programmed death 1/programmed death ligand 1 blockade significantly enhanced antitumor immunity. Consistently, tumor‐infiltrating ILC3s correlated with negative prognosis in patients with HCC, which could be functionally mediated by acetate. Conclusions: These findings suggested that modifying bacteria, changing SCFAs, reducing IL‐17A‐producing ILC3 infiltration, and combining with immune checkpoint inhibitors will contribute to the clinical treatment of HCC.

Background We have previously discovered a relationship between the low expression of protein tyrosine phosphatase, receptor type O (PTPRO) in tumor-infiltrating T cells and immunosuppression. The aim of the present study was to investigate the relationship between decreased PTPRO and increased programmed death ligand 1 (PD-L1) in both the peripheral monocytes and tumor-infiltrating macrophages of human hepatocellular carcinoma (HCC). Methods The expression and correlation of all the indices were explored in monocytes and tumor-infiltrating macrophages within both human and mice HCC. The mechanic regulations were studied by using both in vitro and in vivo studies. Results We found a significant decrease in PTPRO in HCC peripheral monocytes that was associated with increased PD-L1 expression in peripheral monocytes and tumor-associated macrophages (TAMs) in HCC. Monocyte PD-L1 and PTPRO therefore could serve as valuable prognostic indicators for post-surgery patients with HCC and were associated with increased T-cell exhaustion (Tim3+T cells). A depletion of PTPRO promoted PD-L1 secretion in both monocytes and macrophages through the JAK2/STAT1 and JAK2/STAT3/c-MYC pathways. Increased IL-6 expression was associated with activation of JAK2/STAT3/c-MYC and with decreased PTPRO expression through the STAT3/c-MYC/miR-25–3 p axis. Monocytes and TAMs showed significantly increased miR-25–3 p expression, which could target the 3′ untranslated region of PTPRO. The miR-25–3 p expression positively correlated with serum IL-6 levels, but inversely correlated with PTPRO in HCC monocytes. IL-6/STAT3/c-MYC activation enhanced in vitro miR-25–3 p transcription and decreased PTPRO, while further promoting PD-L1 secretion. Adoptive cell transfer of c-MYC/miR-25–3 p–modified monocytes promoted tumor growth by downregulating PTPRO and causing a PD-L1–induced immunosuppression in an orthotopic tumor transplantation model. Conclusions Increased serum IL-6 downregulated PTPRO expression in HCC monocytes and macrophages by activating STAT3/c-MYC/miR-25–3 p and by further enhancing PD-L1 expression through JAK2/STAT1 and JAK2/STAT3/c-MYC signaling.

The host microbiota is closely associated with tumor initiation and progression in multiple solid tumors including gastric cancer. The aim of this study was to investigate in patients with gastric cancer whether there are alterations in gastric microbiota and any potential association these may have with immune dysregulation. 16S rRNA gene sequencing was used to analyze tumor microbiota of 53 patients with gastric cancer and gastric mucosal tissue microbiota of 30 patients with chronic gastritis. The effect of microbiota on the tumor microenvironment (TME) was studied by single-cell sequencing, immunohistochemistry, multiplex immunofluorescence staining, and flow cytometry, as well as in a mouse model of primary gastric cancer. The gastric cancer microbiota was characterized by reduced microbial diversity and enrichment of the Oceanobacter, Methylobacterium, and Syntrophomonas genera. Intratumoral Methylobacterium was significantly associated with poor prognoses in patients with gastric cancer. It also was inversely correlated with the frequency of CD8+ tissue-resident memory T (TRM) cells in the TME. TGFβ was significantly reduced in gastric cancer samples with higher abundance of Methylobacterium. Finally, we verified that Methylobacterium can decrease TGFβ expression and CD8+ TRM cells in the tumor by establishing a mouse model of primary gastric cancer. The results suggest that tumor microbiota and exhausted CD8+ TRM cells in the TME of gastric cancer are significantly correlated, and that Methylobacterium may play a role in gastric carcinogenesis.

Although the presence of tertiary lymphoid structures (TLS) correlates with positive responses to immunotherapy in many solid malignancies, the mechanism by which TLS enhances anti-tumor immunity is not well understood. The present study aimed to investigate the underlying cross-talk circuits between B cells and tissue-resident memory T (Trm) cells within the TLS and to understand their role in the context of immunotherapy. Immunostaining and hematoxylin and eosin staining of TLS and CXCL13⁺CD103⁺CD8⁺Trm cells were performed on tumor sections from patients with gastric cancer (GC). The mechanism of communication between B cells and CXCL13⁺CD103⁺CD8⁺Trm cells was determined both in vitro and in vivo. The effect of CXCL13⁺CD103⁺CD8⁺Trm cells in suppressing tumor growth was evaluated through anti-PD-1 therapy. The presence of TLS and CXCL13⁺CD103⁺CD8⁺Trm cells in tumor tissues favored a superior response to anti-PD-1 therapy in GC patients. Additionally, our research identified that activated B cells enhanced CXCL13 and granzyme B secretion by CD103⁺CD8⁺Trm cells. Mechanistically, B cells facilitated the glycolysis of CD103⁺CD8⁺Trm cells through the Lymphotoxin Alpha (LTα)/Tumor necrosis factor receptor 2 (TNFR2) axis, and the mTOR signaling pathway played a critical role in CD103⁺CD8⁺Trm cells glycolysis during this process. Moreover, the presence of TLS and CXCL13⁺CD103⁺CD8⁺Trm cells correlated with potent responsiveness to anti-PD-1 therapy in a TNFR2 dependent manner. This study further reveals a crucial role for cellular communication between TLS-associated B cell and CXCL13⁺CD103⁺CD8⁺Trm cells in anti-tumor immunity, providing valuable insights into the potential utilization of the LTα/TNFR2 axis within CXCL13⁺CD103⁺CD8⁺Trm cells for advancing immunotherapy strategies in GC.

Despite a good and overall prognosis, papillary thyroid cancer (PTC) can still affect the quality of life of many patients, and can even be life-threatening due to its invasiveness and metastasis. Emerging studies demonstrate that circular RNAs (circRNAs) participate in the regulation of various cancers. However, the circRNA profile in invasive PTC is still not well understood. Competing endogenous RNA (ceRNA) microarrays were performed to determine circRNAs contributed to the tumorigenesis and invasiveness of PTC. Bioinformatics methods were used to narrow down the candidate circRNAs. Quantitative real-time polymerase chain reaction (qRT-PCR) assays revealed a significant upregulation of hsa_circ_0058124 in PTC tissue and a close correlation with a poor prognosis for PTC patients. RNA fluorescence in situ hybridization and Cell fractionation assay were used to investigate the subcellular location of hsa_circ_0058124. Then, we examined the functions of hsa_circ_0058124 in PTC by cell proliferation, cell cycle, apoptosis, migration and invasion assay. Mechanistically, RNA sequencing and GSEA analysis were applied to predict the downstream pathway of hsa_circ_0058124. Dual-luciferase report assays were used to explore the potential miRNA sponge role of hsa_circ_0058124. Western blotting, cell proliferation, cell cycle, cell apoptosis, migration and invasion, and mouse xenograft assay were used to validate the effects of hsa_circ_0058124/NOTCH3/GATAD2A axis on PTC progression. In the current study, a novel hsa_circ_0058124 on 2q35 was identified and explored in PTC. Hsa_circ_0058124 is associated with the malignant features and poor outcomes of PTC patients. Hsa_circ_0058124 acts as an oncogenic driver that promotes PTC cell proliferation, tumorigenicity, tumor invasion, and metastasis, which functions as a competing endogenous RNA to modulate miRNA-218-5p and its target gene NUMB expression, and consequently with repression of the NOTCH3/GATAD2A signaling axis in vitro and in vivo. This study unveils a novel biomarker panel consisting of the hsa_circ_0058124/NOTCH3/GATAD2A axis which is critical for PTC tumorigenesis and invasiveness and may represent a novel therapeutic target for intervening in PTC progression.