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Despite the importance of spliceosome core components in cellular processes, their roles in cancer development, including hepatocellular carcinoma (HCC), remain poorly understood. In this study, we uncover a critical role for SmD2, a core component of the spliceosome machinery, in modulating DNA damage in HCC through its impact on BRCA1/FANC cassette exons and expression. Our findings reveal that SmD2 depletion sensitizes HCC cells to PARP inhibitors, expanding the potential therapeutic targets. We also demonstrate that SmD2 acetylation by p300 leads to its degradation, while HDAC2-mediated deacetylation stabilizes SmD2. Importantly, we show that the combination of Romidepsin and Olaparib exhibits significant therapeutic potential in multiple HCC models, highlighting the promise of targeting SmD2 acetylation and HDAC2 inhibition alongside PARP inhibitors for HCC treatment. The relevance of spliceosome core components in cancer is less understood. Here the authors show SmD2, a core component of the spliceosome machinery, is under acetylation-dependent regulation, which could be targeted to enhance sensitivity to PARP inhibitors in hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer with a highly immunosuppressive tumor microenvironment and a typical pattern of disturbances in hepatic lipid metabolism. Long non‐coding RNAs are shown to play an important role in the regulation of gene expression, but much remains unknown between tumor microenvironment and lipid metabolism as a bridging molecule. Here, long intergenic nonprotein coding RNA 01116 (LINC01116) acts as this molecular which is frequently upregulated in HCC patients and associated with HCC progression in vitro and in vivo is identified. Mechanistically, LINC01116 stabilizes EWS RNA‐binding protein 1 (EWSR1) by preventing RAD18 E3 Ubiquitin Protein Ligase (RAD18) ‐mediated ubiquitination. The enhanced EWSR1 protein upregulates peroxisome proliferator activated receptor alpha (PPARA) and fatty acid binding protein1 (FABP1) expression, a long‐chain fatty acid (LCFA) transporter, and thus cancer cells outcompete T cells for LCFAs, especially linoleic acid, for seeding their own growth, leading to T cell malfunction and HCC malignant progression. In a preclinical animal model, the blockade of LINC01116 leads to enhanced efficacy of anti‐PD1 treatment accompanied by increased cytotoxic T cell and decreased exhausted T cell infiltration. Collectively, LINC01116 is an immunometabolic lncRNA and the LINC01116‐EWSR1‐PPARA‐FABP1 axis may be targetable for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) remains a global challenge. Finding new specific targets has significant clinical value for the treatment of hepatocellular carcinoma. In this study, we discovered a new biomarker targeting HCC. At present, the role of Inner Membrane Mitochondrial Protein (IMMT) in various malignant tumors is receiving increasing attention, but its molecular mechanism of action in the malignant process of HCC has not been fully elucidated. This study aims to investigate the key regulatory mechanisms of IMMT in the formation of HCC. Using TCGA data and clinical HCC samples, we first studied the expression of IMMT in HCC tissues and its correlation with malignant prognosis of patients. The regulatory effect of IMMT on HCC was studied by lentivirus infection. In vitro, the effects of IMMT on the proliferation, migration and apoptosis of cells were investigated by CCK8, colony formation assay, transwell and flow cytometry. Consistently, in vivo experiments, the regulation of tumor growth by IMMT was studied by constructing subcutaneous transplanted tumor and liver carcinoma in situ. In terms of mechanism, we predicted and verified the downstream genes of IMMT with the help of string database. We found that IMMT was significantly up-regulated in HCC tissues and was significantly positively correlated with poor prognosis of patients. Functionally, we demonstrated that IMMT knockdown significantly inhibited HCC cell proliferation, migration and promoted cell apoptosis in vitro. Similarly, the knockdown of IMMT also significantly weakened the progression of tumors in vivo. In terms of mechanism, we demonstrate for the first time that IMMT can regulate the progression of HCC by influencing the activation of PI3K-AKT-mTOR pathway. Collectively, our research findings elucidate the hitherto unexplored important role of the IMMT/PI3K/AKT/mTOR axis in the formation of HCC, and provide a new biomarker for clinical diagnosis and treatment of HCC. [ABSTRACT FROM AUTHOR]

The tumour microenvironment (TME) is a crucial mediator of cancer progression and therapeutic outcome. The TME subtype correlates with patient response to immunotherapy in multiple cancers. Most previous studies have focused on the role of different cellular components in the TME associated with immunotherapy efficacy. However, the specific structure of the TME and its role in immunotherapy efficacy remain largely unknown. We combined spatial transcriptomics with single-cell RNA-sequencing and multiplexed immunofluorescence to identify the specific spatial structures in the TME that determine the efficacy of immunotherapy in patients with hepatocellular carcinoma (HCC) receiving anti-PD-1 treatment. We identified a tumour immune barrier (TIB) structure, a spatial niche composed of SPP1 + macrophages and cancer-associated fibroblasts (CAFs) located near the tumour boundary, which is associated with the efficacy of immune checkpoint blockade. Furthermore, we dissected ligand‒receptor networks among malignant cells, SPP1 + macrophages, and CAFs; that is, the hypoxic microenvironment promotes SPP1 expression, and SPP1 + macrophages interact with CAFs to stimulate extracellular matrix remodelling and promote TIB structure formation, thereby limiting immune infiltration in the tumour core. Preclinically, the blockade of SPP1 or macrophage-specific deletion of Spp1 in mice led to enhanced efficacy of anti-PD-1 treatment in mouse liver cancer, accompanied by reduced CAF infiltration and increased cytotoxic T-cell infiltration. We identified that the TIB structure formed by the interaction of SPP1 + macrophages and CAFs is related to immunotherapy efficacy. Therefore, disruption of the TIB structure by blocking SPP1 may be considered a relevant therapeutic approach to enhance the therapeutic effect of immune checkpoint blockade in HCC. Only a limited number of patients with hepatocellular carcinoma (HCC) benefit from tumour immunotherapy, which significantly hinders its application. Herein, we used multiomics to identify the spatial structure of the tumour immune barrier (TIB), which is formed by the interaction of SPP1+ macrophages and cancer-associated fibroblasts in the HCC microenvironment. This structure constrains immunotherapy efficacy by limiting immune cell infiltration into malignant regions. Preclinically, we revealed that blocking SPP1 or macrophage-specific deletion of Spp1 in mice could destroy the TIB structure and sensitize HCC cells to immunotherapy. These results provide the first key steps towards finding more effective therapies for HCC and have implications for physicians, scientists, and drug developers in the field of HCC. [Display omitted] • Integration of multi-omics was used to identify a TIB (tumour immune barrier) structure in the HCC microenvironment. • This TIB structure contributes to the efficacy of immunotherapy. • SPP1 + macrophages and CAFs interact to promote the formation of the TIB structure and limit immune infiltration of tumours. • Blockade of SPP1 or macrophage-specific deletion of Spp1 in mice can destroy the TIB structure and sensitize HCC to immunotherapy. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is one of the most prevalent and leading causes of cancer-related mortality worldwide. Long non-coding RNAs (lncRNAs) have been demonstrated to play vital roles in cancer development and progression. The lncRNA PWRN1 (PWRN1), acts as a tumor suppressor factor, which is low expressed in some cancers. However, the molecular mechanisms underlying the effects of PWRN1 , especially the regulatory relationship with RNA binding protein in HCC remain largely unknown. In the present study, we demonstrated that PWRN1 was significantly down-regulated in HCC and correlated with better prognosis; furthermore, gain-of-function experiments showed that PWRN1 inhibited the proliferation of HCC cells. We further found that PWRN1 up-regulated pyruvate kinase activity and thus hinders the proliferation of HCC in vitro and in vivo. Mechanistically, pyruvate kinase M2 (PKM2) was bound to it and maintained the high activity state of PKM2, thereby hindering PKM2 from entering the nucleus in the form of low-activity dimers, reducing the expression of c-Myc downstream gene LDHA , leading to a decrease in lactate levels, and inhibiting the growth of tumor cells. In addition, PWRN1 was found to inhibit aerobic glycolysis. Finally, TEPP-46, a pyruvate kinase activator, appeared to inhibit HCC proliferation by maintaining tetramer stability and increasing pyruvate kinase activity. Taken together, our results provide new insights into the biology hindering HCC proliferation and indicate that PWRN1 in combination with PKM2 activators might represent a novel therapeutic target for HCC. • PWRN1 overexpression inhibits the cell proliferation of HCC. • PWRN1 physically interacts with the glycolytic enzyme PKM2, inhibits glycolysis and lactate production. • PWRN1 inhibits HCC growth through impeding PKM2 nuclear translocation and activating PKM2 activity. • The combination of PWRN1 with PKM2 activator would be promsing for the treatment of HCC. [ABSTRACT FROM AUTHOR]