The epigenetic regulator protein arginine methyltransferase 5 (PRMT5) is aberrantly overexpressed in triple-negative breast cancer (TNBC) and represents a promising therapeutic target. Currently reported PRMT5-targeting PROTAC degraders (MS4322 and MS115) are both derived from a tetrahydroisoquinoline scaffold. These compounds require treatment for more than five days to exert effective antiproliferative activities, and no in vivo antitumor efficacy has been reported. To address these limitations, we adopted the carbazole-based PRMT5 inhibitor PJ-68, which features a lower molecular weight and a more accessible linker attachment site. Herein, we reported a series of novel PRMT5 degraders with carbazole scaffold. The representative compound YZ-17 degraded PRMT5 (DC50 = 2.2 μM in HCC1806 and 3.3 μM in HCC1937 cells) and its adaptor protein MEP50 (DC50 = 2.0 μM and 2.9 μM, respectively) within 24 h. YZ-17 also suppressed PRMT5-mediated symmetric dimethylarginine (sDMA) modification and colony formation, induced G1 phase cell cycle arrest, and displayed favorable antiproliferative activities across several TNBC cell lines (IC50 = 2.6 - 3.7 μM). Importantly, YZ-17 showed in vivo efficacy in an HCC1806 xenograft model, achieving a tumor growth inhibition (TGI) of 44.12% at 30 mg/kg (i.p., every other day) without obvious toxicity. Collectively, YZ-17 represents a structurally novel PRMT5 degrader with rapid onset of action, effective in vitro and in vivo anti-TNBC activity, offering a distinct chemical tool for further functional studies of PRMT5.

Extrachromosomal circular DNA (eccDNA), characterized by abundant amplicons and high chromatin accessibility, contributes to tumor heterogeneity and transcriptional activity; however, its single-cell dynamics in cutaneous squamous cell carcinoma (CSCC) remain poorly understood. Here, we developed a single-cell framework eccDNAscope that reconstructs eccDNA structures and infers clonal trajectories from scATAC-seq data. Integrative analysis of 154,624 single cells revealed that eccDNAs were broadly distributed across diverse cell types but exhibited striking enrichment at promoter regions (79.94%), where they were associated with elevated expression of cell type-specific eccDNA-associated genes. The framework identified both known oncogenic eccDNAs (MYC) and previously unrecognized eccDNAs (PTMA, NRP2, and KLF7), which were independently validated by DNA fluorescence in situ hybridization (FISH), super-resolution microscopy, Immuno-FISH, and Circle-seq. These eccDNAs displayed enhanced transcriptional activity in the epithelial cell populations in which they were detected. We further identified CSCC-specific eccDNAs that were enriched in cell cycle-related pathways, including CACYBP, which was exclusively detected in CSCC, but was not observed in actinic keratosis (AK) or para-tumor tissues. Finally, eccDNA-based phylogenetic reconstruction identified conserved and tissue-specific eccDNA programs during disease evolution, and highlighted recurrent eccDNAs, particularly PTMA and CACYBP, as potential drivers of CSCC progression. Collectively, our single-cell analysis provides a framework for dissecting eccDNA-mediated oncogenesis and offers insights into therapeutic strategies targeting eccDNA-positive clones in cancer.

[This retracts the article DOI: 10.1016/j.isci.2019.10.007.].

BACKGROUND:Chimeric antigen receptor (CAR) macrophage therapy shows significant potential for solid tumors owing to the intrinsic tumor infiltration and phagocytic capacity of macrophages. However, its clinical translation is limited by macrophage phenotypic plasticity within the immunosuppressive tumor microenvironment and the complexity of ex vivo cell manufacturing. It is essential to develop techniques that enable macrophages to be activated specifically by antigens while sustaining their proinflammatory activity in vivo. METHODS:Here, we report a mannose-modified lipid nanoparticle (LNP) platform for the co-delivery of CAR-encoding messenger RNA (mRNA) and the Toll-like receptor (TLR) 7/8 agonist resiquimod (R848), enabling in situ generation of proinflammatory CAR macrophages. In vitro, we assessed macrophage-preferential uptake, CAR expression efficiency, TLR7/8 agonist-mediated macrophage polarization, and immune activation. In vivo efficacy was assessed in syngeneic and humanized mouse models of triple-negative breast cancer, including postoperative recurrence and lung metastasis models. RESULTS:Systemic administration of M-LNP/CAR+R848 induced robust CAR expression in tumor-associated macrophages and promoted sustained M1 polarization. Engineered macrophages exhibited enhanced antigen-specific phagocytic activity and tumor cell clearance, and promoted CD8+ T cell proliferation and NK cell infiltration, thus coordinating innate and adaptive immune responses. Functional macrophage depletion experiments demonstrated that tumor control was dependent on macrophages. In vivo treatment significantly reduced the growth of primary tumors, prevented postoperative recurrence, and prolonged survival in mice with lung metastases in both syngeneic and humanized models. CONCLUSIONS:Our findings demonstrate that M-LNPs enabling co-delivery of mRNA and an innate immune agonist enable in situ generation of proinflammatory CAR macrophages and induce durable antitumor immunity. This controllable and non-integrative strategy allows tunable immune activation, provides a flexible platform for CAR macrophage-based immunotherapy in triple-negative breast cancer.

HER2-positive breast cancer accounts for approximately 15

In the clinic, anti-tumor angiogenesis is commonly employed for treating recurrent, metastatic, drug-resistant triple-negative, and advanced breast cancer. Our previous research revealed that the deubiquitinase STAMBPL1 enhances the stability of MKP-1, thereby promoting cisplatin resistance in breast cancer. In this study, we discovered that STAMBPL1 could upregulate the expression of the hypoxia-inducible factor HIF1α in breast cancer cells. Therefore, we investigated whether STAMBPL1 promotes tumor angiogenesis. We demonstrated that STAMBPL1 increased HIF1A transcription in a non-enzymatic manner, thereby activating the HIF1α/VEGFA signaling pathway to facilitate triple-negative breast cancer angiogenesis. Through RNA-seq analysis, we identified the transcription factor GRHL3 as a downstream target of STAMBPL1 that is responsible for mediating HIF1A transcription. Furthermore, we discovered that STAMBPL1 regulates GRHL3 transcription by interacting with the transcription factor FOXO1. These findings shed light on the role and mechanism of STAMBPL1 in the pathogenesis of breast cancer, offering novel targets and avenues for the treatment of triple-negative and advanced breast cancer.

BACKGROUND:Hepatocellular carcinoma (HCC) is the most prevalent form of liver cancer and is associated with a poor prognosis. Current treatment options for advanced HCC remain limited, highlighting the need for more effective and safer therapies. PURPOSE:This study aimed to elucidate the anti-cancer efficacy and explore the molecular mechanism of Bruceantin (BCT) against HCC. METHODS:We screened natural compounds using an extensive literature review and CCK-8 assays to identify novel therapeutic candidates. Using in vitro (HepG2.2.15 and Hep3B) and in vivo models, we assessed the BCT's effects through CCK-8, colony formation, wound-healing, flow cytometry, Hematoxylin and eosin (H&E) staining, immunohistochemistry (IHC), qPCR, Western blot (WB), Luciferase reporter assay, and CETSA. RESULTS:Bruceantin (BCT) significantly inhibited HCC cell proliferation and migration and induced apoptosis. In mouse xenograft models, it markedly suppressed tumor growth without observable toxicity. Transcriptomic profiling revealed that BCT broadly downregulated ribosomal protein genes, with RPL27A showing the most notable reduction. Further investigations demonstrated that RPL27A plays a crucial role in supporting HCC cell survival and inhibiting apoptosis, and its high expression is clinically associated with poor prognosis. Mechanistically, BCT decreased RPL27A expression by inhibiting c-Myc's transcriptional activity, thus preventing its capacity to activate RPL27A transcription. This disruption of the c-Myc/RPL27A axis contributes to BCT's antitumor effects. CONCLUSION:This study reveals a new molecular mechanism underlying BCT's antitumor activity and supports its potential as a therapeutic agent for HCC.

Traumatic brain injury (TBI) is characterized by high rates of death and disability. Necroptosis is reported to be involved in neuronal death after TBI. However, additional molecules and related mechanisms underlying necroptosis, particularly during TBI, remain to be elucidated. mTOR and two of its three substrates (4EBP1 and ULK1) are involved in necroptosis. However, direct evidence linking necroptosis to S6K, another key substrate of mTORC1, has been lacking. In this study, we aimed to investigate the regulated role of u201CS6K1-glucocorticoid-inducible kinase-1 (SGK1)u201D pathway in neuronal necroptosis after TBI. We first showed that the u201CS6K1u2013SGK1u201D pathway was activated during neuronal necroptosis in TNF-u03B1/Smac mimics/Z-VAD-FMK-induced necroptotic cell model and mouse TBI model. Then, inhibition of the u201CS6K1u2013SGK1u201D pathway could decrease necroptosis by regulating the MLKL activation. Next, a rescue assay indicated that S6K1 may regulate necroptosis through modulating SGK1 expression, while not through binding with SGK1. Finally, S6K1 inhibition alleviated neuronal necroptosis, neuro-inflammation, and functional damage via SGK1 in mice after TBI. Our results showed a non-canonical role of u201CS6K1u2013SGK1u201D pathway in neuronal necroptosis following TBI in mice, which will provide a potential therapeutic target for necroptosis treatment in TBI and other necroptosis-related disorders.

mTOR plays a pivotal role in cancer growth control upon amino acid response. Recently, CDK inhibitor P27KIP1 has been reported as a noncanonical inhibitor of mTOR signaling in MEFs, via unclear mechanisms. Here, we find that P27KIP1 degradation via E3 ligase TRIM21 is inhibited by human micropeptide hSPAR through its C-terminus (hSPAR-C), causing P27KIP1's cytoplasmic accumulation in breast cancer cells. Furthermore, hSPAR/hSPAR-C also serves as an inhibitor of glutamine transporter SLC38A2 expression and thereby decreases the cellular glutamine levels specifically in cancer cells. The resultant glutamine deprivation sequentially triggers translocation of cytoplasmic P27KIP1 to lysosomes, where P27KIP1 disrupts the Ragulator complex and suppresses mTORC1 assembly. Administration of hSPAR or hSPAR-C significantly impedes breast cancer cell proliferation and tumor growth in xenograft models. These findings define hSPAR as an intrinsic control factor for cellular glutamine levels and as a novel tumor suppressor inhibiting mTORC1 assembly.