Despite of advances in treatment options, hepatocellular carcinoma (HCC) remains nearly incurable and has been recognized as the third leading cause of cancer-related deaths worldwide. As a deubiquitinating enzyme, the antitumor effect of ubiquitin-specific peptidase 53 (USP53) has been demonstrated on few malignancies. In this study, we investigated the potential antitumor role of USP53 in HCC. The results showed that USP53 was downregulated in HCC tissues as well as in HCC cell lines using both in silico data as well as patient samples. Furthermore, the ectopic expression of USP53 inhibited the proliferation, migration and invasion, and induced the apoptosis of HCC cells. Co-immunoprecipitation (CO-IP) assay and mass spectrometry (MS) combined with the gene set enrichment analysis (GSEA) identified cytochrome c (CYCS) as an interacting partner of USP53. USP53 overexpression increased the stability of CYCS in HCC cells following cycloheximide treatment. Finally, the overexpression of CYCS compensated for the decreased apoptotic rates in cells with USP53 knocked down, suggesting that USP53 induced the apoptosis in HCC cells through the deubiquitination of CYCS. To summarize, we identified USP53 as a tumor suppressor as well as a therapeutic target in HCC, providing novel insights into its pivotal role in cell apoptosis.

Cancer treatment is continually advancing, with immunotherapy gaining prominence as a standard modality that has markedly improved the management of various malignancies. Despite these advancements, the efficacy of immunotherapy remains variable, with certain cancers exhibiting limited response and patient outcomes differing considerably. Thus, enhancing the effectiveness of immunotherapy is imperative. A promising avenue is mRNA delivery, employing carriers such as liposomes, peptide nanoparticles, inorganic nanoparticles, and exosomes to introduce mRNA cargos encoding tumor antigens, immune-stimulatory, or immune-modulatory molecules into the tumor immune microenvironment (TIME). This method aims to activate the immune system to target and eradicate tumor cells. In this review, we introduce the characteristics and limitations of these carriers and summarize the application and mechanisms of currently prevalent cargos in mRNA-based tumor treatment. Additionally, given the significant clinical application of immune checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR)-based cell therapies in solid tumors (including melanoma, non-small-cell lung cancer, head and neck squamous cell carcinoma, triple-negative breast cancer, gastric cancer) and leukemia, which have become first-line treatments, we highlight and discuss recent progress in combining mRNA delivery with ICIs, CAR-T, CAR-NK, and CAR-macrophage therapies. This combination enhances the targeting capabilities and efficacy of ICIs and CAR-cell-based therapies, while also mitigating the long-term off-target toxicities associated with conventional methods. Finally, we analyze the limitations of current mRNA delivery systems, such as nuclease-induced mRNA instability, immunogenicity risks, complex carrier production, and knowledge gaps concerning dosing and safety. Addressing these challenges is crucial for unlocking the potential of mRNA in cancer immunotherapy. Overall, exploring mRNA delivery enriches our comprehension of cancer immunotherapy and holds promise for developing personalized and effective treatment strategies, potentially enhancing the immune responses of cancer patients and extending their survival time.

BACKGROUND Immunotherapy presents both promises and challenges in treating hepatocellular carcinoma (HCC) due to its complex immunological microenvironment. The role of B cells, a key part of the immune system, remains uncertain in HCC. AIM To identify B-cell-specific signatures and reveal novel immunophenotyping and therapeutic targets for HCC. METHODS Using the Tumor Immune Single-cell Hub 2 database, we identified B-cell-related genes (BRGs) in HCC. Gene enrichment analysis was performed to explore the possible collaboration between B cells and T cells in HCC. We conducted univariate Cox regression analysis using The Cancer Genome Atlas liver HCC collection dataset to find BRGs linked to HCC prognosis. Subsequently, least absolute shrinkage and selection operator regression was utilized to develop a prognostic model with 11 BRGs. The model was validated using the International Cancer Genome Consortium dataset and GSE76427. RESULTS The risk score derived from the prognostic model emerged as an independent prognostic factor for HCC. Analysis of the immune microenvironment and cell infiltration revealed the immune status of various risk groups, supporting the cooperation of B and T cells in suppressing HCC. The BRGs model identified new molecular subtypes of HCC, each with distinct immune characteristics. Drug sensitivity analysis identified targeted drugs effective for each HCC subtype, enabling precision therapy and guiding clinical decisions. CONCLUSION We clarified the role of B cells in HCC and propose that the BRGs model offers promising targets for personalized immunotherapy.

Background and Aims: Hyperlipidemia has been extensively recognized as a high-risk factor for non-alcoholic steatohepatitis (NASH); however, clinical susceptibility to NASH is highly heterogeneous. The key controller(s) of NASH susceptibility in patients with hyperlipidemia have not yet been elucidated. Here, we aimed to reveal the key regulators of NASH in patients with hyperlipidemia and to explore its role and underlying mechanisms. Approach and results: To identify the predominant suppressors of NASH in the setting of hyperlipidemia, we collected liver biopsy samples from patients with hyperlipidemia, with or without NASH, and performed RNA-seq analysis. Notably, decreased LIM domain only 7 (LMO7) expression robustly correlated with the occurrence and severity of NASH. Although overexpression of LMO7 effectively blocked hepatic lipid accumulation and inflammation, LMO7 deficiency in hepatocytes greatly exacerbated diet-induced NASH progression. Mechanistically, lysine 48 (K48)-linked ubiquitin-mediated proteasomal degradation of tripartite motif 47 (TRIM47) and subsequent inactivation of the JNK/p38 MAPK cascade are required for the protective function of LMO7 in NASH. Conclusions: These findings provide proof-of-concept evidence supporting LMO7 as a robust suppressor of NASH in the context of hyperlipidemia, indicating that targeting the LMO7-TRIM47 axis is a promising therapeutic strategy for NASH. Export

Aberrant upregulation of the intracellular antioxidant glutathione (GSH) is implicated in promoting tumor proliferation, inducing drug resistance, and inhibiting ferroptosis across various malignancies, including hepatocellular carcinoma (HCC). Targeting the mechanism underlying GSH upregulation in HCC could represent a therapeutic strategy to improve patient outcomes. In this study, we employed a genome-wide CRISPR/Cas9 screen and targeted metabolomics to identify the acetyltransferase ARD1 as a pivotal facilitator of de novo GSH synthesis in HCC. Notably, ARD1 upregulation was positively correlated with elevated GSH levels and poor prognosis in patients with HCC. In vivo and in vitro functional assays revealed that ARD1 promoted HCC cell proliferation and inhibited ferroptosis in a GSH-dependent manner. LC/MS-MS–based stable isotope labeling revealed that ARD1 increased GSH levels by stabilizing γ-glutamylcysteine ligase catalytic (GCLC) subunit mRNA, which was mediated by the RNA-binding protein PABPC1. Mechanistically, ARD1 acetylated PABPC1 at Ki67, augmenting its cytoplasmic retention by disrupting PABPC1–importin α7 complex formation. Cytoplasmic PABPC1 then interacted with eIF4G to collaboratively stabilize GCLC mRNA, preventing its degradation, increasing GSH synthesis, and ultimately conferring ferroptosis resistance in HCC cells. Furthermore, oxidative stress induced by hydrogen peroxide suppressed ARD1 ubiquitination and degradation, thereby promoting PABPC1 cytoplasmic translocation and inducing GCLC expression. ARD1 suppression promoted sorafenib-mediated ferroptosis in xenografts derived from patients with HCC tumors with high ARD1 and GCLC expression. Overall, this research uncovers an oxidative stress–ARD1–PABPC1–GCLC axis with a crucial role in GSH metabolic reprogramming and ferroptosis regulation in HCC and reveals a strategy for ferroptosis-based targeted therapy for HCC. Significance: The acetyltransferase ARD1 promotes hepatocellular carcinoma progression, inhibits ferroptosis by upregulating GCLC to facilitate de novo synthesis of glutathione, and can be targeted to improve sorafenib efficacy.