M2-polarized tumor-associated macrophages (TAMs) are a key factor contributing to the poor prognosis of pancreatic ductal adenocarcinoma (PDAC). While various factors within the tumor microenvironment (TME) drive their formation, the role of PDAC-derived exosomes in this process remains unclear. We aim to clarify the regulatory impacts of tumor-derived exosomes to TAMs. After the intratumoral injection to subcutaneous tumor of C57BL/6 mice, we demonstrated PDAC-derived exosomes exacerbate PDAC progression, accompanied with upregulated M2 phenotype of TAMs and unaffected proliferation signatures. Through intratumoral injection model and multi-Omics analyses, we identified CCT6A as a novel tumor-derived exosomal protein, bridging TAMs M2 polarization and PDAC prognosis. Co-culture with exosomes derived from CCT6A^high PDAC leads to greater M2 phenotype of TAMs via PI3K-AKT signaling. According to proteomics data, chemokines’ abundance reduces over tenfold once exosomal CCT6A absence, including CXCL1, CXCL3, CCL20 and CCL5, whose interaction with CCT6A in PDAC cells was confirmed by interactomics data. Moreover, we found silencing CCT6A abrogated the antagonism effects of CD47 antibody immunotherapy. Our findings implied that the subunit of the T-complex protein Ring Complex (TRiC) CCT6A serves as a matchmaker during exosome-mediated chemokines transfer from PDAC to TAMs. Silencing CCT6A effectively sensitized PDAC to CD47 antibody immunotherapy in vivo.

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.