Glutaryl-CoA dehydrogenase suppresses tumor progression and shapes an anti-tumor microenvironment in hepatocellular carcinoma.

BACKGROUND & AIMS: Crotonylation, a crotonyl-CoA-based non-enzymatic protein translational modification, affects diverse biological processes, such as spermatogenesis, tissue injury, inflammation, and neuropsychiatric diseases. Crotonylation shows decreased in hepatocellular carcinomas (HCCs), but the mechanism remains unknown. In this study, we aim to describe the role of glutaryl-CoA dehydrogenase (GCDH) in tumor suppression. METHODS: Three cohorts containing 40, 248 and 17 pairs of samples were used to evaluate the link between GCDH expression levels and the HCC clinical characteristics as well as anti-PD-1 response. Subcutaneous xenograft, orthotopic xenograft, Trp53Δhep/Δhep; MYC- as well as Ctnnboe; METoe- driven mouse models were adopted to validate GCDH effects on HCC suppression. RESULTS: GCDH depletion promoted HCC growth and metastasis, whereas its overexpression reversed these processes. As GCDH converts glutaryl-CoA to crotonyl-CoA to increase crotonylation levels, we performed lysine crotonylome analysis and identified the pentose phosphate pathway (PPP) and glycolysis-related proteins PGD, TKT, and ALDOC as GCDH-induced crotonylation targets. Crotonyl-bound targets showed allosteric effects that controlled their enzymatic activities, leading to decreases in ribose 5-phosphate and lactate production, further limiting the Warburg effect. PPP blockade also stimulated peroxidation, synergizing with senescent modulators to induce senescence in GCDHhigh cells. These cells induced the infiltration of immune cells by the senescence-associated secretory cell phenotype (SASP) to shape an anti-tumor immune microenvironment. Meanwhile, the GCDHlow population was sensitized to anti-programmed cell death protein 1 (PD-1) therapy. CONCLUSION: GCDH inhibits HCC progression via crotonylation-induced suppression of the PPP and glycolysis, resulting in HCC cell senescence. The senescent cell further shapes an anti-tumor microenvironment by SASP. The GCDHlow population is vulnerable to anti-PD-1 therapy because more PD-1+CD8+ T cells are exhibited in GCDHlow population. IMPACT AND IMPLICATIONS: GCDH is a favorable prognostic indicator in liver, lung, and renal cancers. In addition, most of GCDH depletion-induced toxic metabolites originate from the liver, accumulate locally, and cannot cross the blood-brain barrier. Therefore, studies on the correlation between GCDH and liver cancer would contribute to discovering the initiation and progression of hepatocellular carcinoma, of which over 70% of patients occupied >2-fold GCDH downregulation. Given that the GCDHlow and GCDHhigh HCC population can be distinguished based on serum glucose and ammonia levels, it will be worthwhile to evaluate the curative effects of pro-senescent and immune-therapeutic strategies based on the expression levels of GCDH.

The XOR-IDH3α axis controls macrophage polarization in hepatocellular carcinoma.

BACKGROUND & AIMS: Tumor-associated macrophages (TAMs) are indispensable in the hepatocellular carcinoma (HCC) tumor microenvironment. Xanthine oxidoreductase (XOR), also known as xanthine dehydrogenase (XDH), participates in purine metabolism, uric acid production, and macrophage polarization to a pro-inflammatory phenotype. However, the role of XOR in HCC-associated TAMs is unclear. METHODS: We evaluated the XOR level in macrophages isolated from HCC tissues and paired adjacent tissues. We established diethylnitrosamine/carbon tetrachloride (CCl4)-induced and orthotopically implanted HCC mouse models using mice with Xdh-specific depletion in the myeloid cell lineage (Xdhf/fLyz2cre) or Kupffer cells (Xdhf/fClec4fcre). We determined metabolic differences using specific methodologies, including metabolomics and metabolic flux. RESULTS: We found that XOR expression was downregulated in HCC TAMs and positively correlated with patient survival, which was strongly related to the characteristics of the tumor microenvironment, especially hypoxia. Using HCC-inflicted mice (Xdhf/fLyz2cre and Xdhf/fClec4fcre), we revealed that XOR loss in monocyte-derived TAMs rather than Kupffer cells promoted their M2 polarization and CD8+ T-cell exhaustion, which exacerbated HCC progression. In addition, the tricarboxylic acid cycle was disturbed, and the generation of α-ketoglutarate was enhanced within XOR-depleted macrophages. XOR inhibited α-ketoglutarate production by interacting with IDH3α catalytic sites (K142 and Q139). The increased IDH3α activity caused increased adenosine and kynurenic acid production in TAMs, which enhanced the immunosuppressive effects of TAMs and CD8+ T cells. CONCLUSIONS: The XOR-IDH3α axis mediates TAM polarization and HCC progression and may be a small-molecule therapeutic or immunotherapeutic target against suppressive HCC TAMs. IMPACT AND IMPLICATIONS: Immunotherapies have been widely applied to the treatment of hepatocellular carcinoma (HCC), but to date they have been associated with unsatisfactory efficacy. The tumor microenvironment of HCC is full of different infiltrating immune cells. Tumor-associated macrophages (TAMs) are vital components in the tumor microenvironment and are involved in HCC progression. Herein, we confirm the downregulation of XOR expression in TAMs isolated from human HCC. The loss of XOR in monocyte-derived macrophages increases IDH3 activity and results in an increase in α-ketoglutarate production, which can promote M2-like polarization. Additionally, XOR-null TAMs derived from monocytes promote CD8+ T-cell exhaustion via the upregulation of immunosuppressive metabolites, including adenosine and kynurenic acid. Given the prevalence and high rate of incidence of HCC and the need for improved therapeutic options for patients, our findings identify potential therapeutic targets that may be further studied to develop improved therapies.

Analysis of Comfort during Transfer by a Dual-Arm Care Robot Based on Human Body Pressure and Surface Electromyographic Signals.

In-home elderly care faces a crucial challenge regarding mobility among essential assistive devices, for which dual-arm care robots present a viable solution. However, ensuring human comfort in human-robot interactions necessitate quantifiable standards. Currently, the field lacks accurate biomechanical model solutions and objective comfort evaluation. In response to this need, this study proposes a method for solving human-robot statics models based on real-time pressure and position information. Employing the Optitrack motion capture system and Tekscan pressure sensors, we collect real-time positional and pressure data. This information is then incorporated into our human-robot statics model, facilitating the instantaneous calculation of forces and moments within the human body's sagittal plane. Building on this, comprehensive research literature review and meticulous questionnaire surveys are conducted to establish a comprehensive comfort evaluation function. To validate this function, experiments are performed to enable real-time assessment of comfort levels experienced during the process of transferring the human body. Additionally, the Noraxon surface electromyography (sEMG) sensors are utilized to capture real-time sEMG signals from the erector spinae, adductor muscles and quadratus lumborum, thereby providing objective validation for the comfort evaluation function. The experimental findings demonstrate that the proposed methodology for evaluating comfort achieves an accuracy rate of 85.1%.