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Cancer cells often exhibit fragmented mitochondria and dysregulated mitochondrial dynamics, but the underlying mechanism remains elusive. Here, we found that the mitochondrial protein death-associated protein 3 (DAP3) is localized to mitochondria and promotes the progression of hepatocellular carcinoma (HCC) by regulating mitochondrial function. DAP3 can promote the proliferation, migration, and invasion of HCC cells in vitro and in vivo by increasing mitochondrial respiration, inducing the epithelial-mesenchymal transition (EMT), and slowing cellular senescence. Mechanistically, DAP3 can increase mitochondrial complex I activity in HCC cells by regulating the translation and expression of MT-ND5. The phosphorylation of DAP3 at Ser185 mediated by AKT is the key event mediating the mitochondrial localization and function of DAP3 in HCC cells. In addition, the DAP3 expression in HCC samples is inversely correlated with patient survival. Our results revealed a mechanism by which DAP3 promotes mitochondrial function and HCC progression by regulating MT-ND5 translation and expression, indicating that DAP3 may be a therapeutic target for HCC., (© 2024. The Author(s).)

Purpose: Anoikis resistance is an important inducer of tumor metastasis. The role of anoikis-related genes (ARGs) in hepatocellular carcinoma (HCC) remains unclear., Methods: A list of ARGs was obtained and regression analysis was employed to assemble an anoikis-related prognostic signature and risk score formula from mRNA data and clinical prognostic data downloaded from The Cancer Genome Atlas database. Quantitative real-time PCR (qRT-PCR) was performed on clinical samples to validate the selected ARGs expressions. Kaplan‒Meier curves, ROC curves, and Cox regression analyses were used to demonstrated the prognostic value of this signature. Biological functional enrichment analysis and immune infiltration analysis were utilized to analyze the differences in potential biological functions, immune cell infiltration, immune functions, and immunotherapeutic responses., Results: A prognostic signature based on 6 ARGs and corresponding prognostic nomogram were established. Our qRT-PCR results showed a higher expression of 6 ARGs in HCC tissues (p value < 0.05). Kaplan‒Meier curves, ROC curves, and Cox regression analyses demonstrated good prognostic value of the signature in HCC (p value < 0.05). Significant differences between the enriched biological functions and immune landscapes of patients in different risk groups were discovered (p value < 0.05). In addition, patients with higher risk scores possibly had poor therapeutic response to transhepatic arterial chemotherapy and embolization or sorafenib, but their responses to immunotherapy might be more effective., Conclusion: A successful anoikis-related prognostic signature and corresponding clinical nomogram were established, which might facilitate better predictions of prognosis and therapeutic responses for HCC patients., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background and Aims: Natural killer (NK) cells are key players in tumor immunosurveillance, and metabolic adaptation manipulates their fate and functional state. The nicotinamide adenine dinucleotide (NAD + ) has emerged as a vital factor to link cellular metabolism and signaling transduction. Here, we identified NAD + metabolism as a central hub to determine the homeostasis and function of NK cells., Approach and Results: NAD + level was elevated in activated NK cells. NAD + supplementation not only enhanced cytokine production and cytotoxicity but also improved the proliferation and viability of NK cells. Intriguingly, the salvage pathway was involved in maintaining NAD + homeostasis in activated NK cells. Genetic ablation or pharmacological blockade of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD + salvage pathway, markedly destroyed the viability and function of NK cells. Mechanistically, NAD + salvage dictated the mitochondrial homeostasis and oxidative phosphorylation activity to support the optimal function of NK cells. However, in human HCC tissues, NAMPT expression and NAD + level were significantly down-regulated in tumor-infiltrating NK cells, which negatively correlated with patient survival. And lactate accumulation in the tumor microenvironment was at least partially responsible for the transcriptional repression of NAMPT in NK cells. Further, deficiency of Nampt in NK cells accelerated the growth of HCC and melanoma. Supplementation of the NAD + precursor nicotinamide mononucleotide (NMN) significantly improved NK antitumor response in both mouse and human cell-derived xenografts., Conclusions: These findings reveal NAD + salvage as an essential factor for NK-cell homeostasis and function, suggesting a potential strategy for invigorating NK cell-based immunotherapy., (Copyright © 2023 American Association for the Study of Liver Diseases.)

Background and Aim: Immune checkpoint inhibitors (ICIs) have been widely used in hepatocellular carcinoma (HCC), while only a subset of patients experience clinical benefit. We aimed to investigate the effects of viral etiology on response to ICIs in HCC and depict the tumor immune microenvironment (TIME) of virally infected and uninfected HCC., Methods: A systematic search was conducted in PubMed, Web of Science, Embase, and the Cochrane central register of controlled trials up to August 2021. Clinical trials reporting the efficacy of ICIs in HCC were eligible. Baseline characteristics including first author, year of publication, National Clinical Trials (NCT) registry number, study region, sample sizes, interventions, line of treatment, and viral status were extracted. Meta-analysis was conducted to generate combined odds ratios (ORs) with 95% confidence intervals (CI) based on random or fixed effect model, depending on heterogeneity. Tumor immune microenvironment was depicted using ESTIMATE and CIBERSORT algorithm., Results: Eight studies involving 1,520 patients were included. Combined data suggested that there was no significant difference of objective response rate (ORR) between virally infected HCC and non-viral HCC patients [OR = 1.03 (95% CI, 0.77-1.37; I 2 = 30.9%, p H  = 0.152)]. Similarly, difference was not observed on ORR between HBV-HCC and HCV-HCC patients [OR = 0.74 (95% CI, 0.52-1.06; I 2 = 7.4%, p H = 0.374)]. The infiltration of immune cells in the tumor microenvironment did not differ by etiology except for M0 macrophages, M2 macrophages, regulatory T cells, naive B cells, follicular helper T cells, activated dendritic cells, activated mast cells, and plasma cells. Despite differences in infiltration observed in specific cell types, the immune score and stromal score were generally comparable among etiology groups., Conclusion: Viral etiology may not be considered as the selection criteria for patients receiving ICIs in HCC, and viral status has little impact on TIME remodeling during HCC tumorigenesis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ding, Dong, Chen, Hong, Yan, Li, Yao, Yan, Yang, Yang and Li.)