Cell Death & Disease最新文献

Colorectal cancer (CRC) is one of the most frequently diagnosed malignant tumors. However, clear evidence explaining the regulatory mechanisms of programmed death ligand 1 (PD-L1) in CRC has been limited. To illustrate the function of YTH N⁶-methyladenosine (m⁶A) RNA binding protein F2 (YTHDF2), we conducted a comprehensive evaluation of expression profiling datasets from online databases and clinical samples. We used a subcutaneous immunodeficient mouse model to investigate the impact of YTHDF2 on CRC. Western blots, flow cytometry, PD-1/PD-L1 binding assay, and cell killing assay were used to assess the relationship between YTHDF2 and PD-L1. We used RNA sequencing, along with methylated RNA immunoprecipitation (MeRIP) and RNA binding protein immunoprecipitation (RIP) sequencing to analyze mRNA expression, m⁶A methylation levels, and YTHDF2 target transcripts. The m⁶A methylation locations of mRNAs were verified using sequence-based RNA adenosine methylation site predictor (SRAMP), MeRIP-qRT-PCR, RIP-qRT-PCR, and a dual-luciferase reporter system. YTHDF2 was upregulated in CRC tissues, and patients with higher YTHDF2 expression had a worse prognosis. The in vivo model showed that YTHDF2 promoted CRC growth, whereas in vitro experiments showed that inhibiting YTHDF2 expression did not affect cell proliferation, migration, or invasion. Mechanistically, interference with YTHDF2 reduced PD-L1 expression and the binding ability between PD-1 and PD-L1. The use of RNA-seq, MeRIP-seq, RIP-seq, and bioinformatics tools confirmed that the speckle type BTB/POZ protein (SPOP) mRNA was a YTHDF2 target and validated its m⁶A methylation sites. After YTHDF2 knockdown, SPOP mRNA stability increased, causing an increase in SPOP expression and a decrease in PD-L1 expression. This study demonstrated that YTHDF2 might upregulate PD-L1 expression by destabilizing m⁶A-containing SPOP mRNA and promote CRC development. The biological effect of the YTHDF2-SPOP-PD-L1 axis presented a promising target for CRC treatment and provided an approach to enhance the efficacy of anti-PD-1/PD-L1 therapy.

Although glioblastoma (GBM) harbors multiple genetic abnormalities leading to cell cycle deregulation, a functional mitotic checkpoint is essential to prevent mitotic catastrophe and tumor cell death. Here, we identify the RNA-binding protein HNRNPH1 as a key post-transcriptional modulator of G2/M checkpoint-associated genes in GBM. HNRNPH1 is overexpressed in malignant cells, especially in the neural- and oligodendrocyte-progenitor-like state, and its expression levels are higher in non-hypoxic regions of the tumor. Knocking out HNRNPH1 causes aberrant splicing and downregulation of several genes involved in cell division. These molecular alterations are associated with G2/M cell cycle arrest, reduced cell proliferation, abnormal cell morphology, and increased nuclear fragmentation. Silencing HNRNPH1 in vivo inhibits the tumor growth of patient-derived GBM cell-originated intracranial xenografts and has significant survival benefits. Together, our results show the critical importance of HNRNPH1 in cell cycle progression and tumor growth, potentially impacting the development of novel strategies to treat GBM.

Monocyte-derived macrophages are usually recruited and play pivotal roles in establishing an immunosuppressive tumor microenvironment, and the interplay between tumor cells and tumor-associated macrophages (TAMs) is crucial for tumor development. However, the detailed mechanisms remain largely unelucidated in certain aggressive human cancers, such as melanoma. Here, through miRNA sequencing analysis, we found the microRNA miR-708-5p was highly enriched in melanoma exosomes, which was dependent on SFRS1. Treatment by melanoma exosomes facilitated M2 polarization of macrophages, while the polarized macrophages in turn promoted melanoma progression and metastasis both in vitro and in vivo. Mechanistically, miR-708-5p directly targets FOXN3, a member of the fork head/winged helix transcription factor family, and subsequently activates the PI3K/AKT/mTOR pathway in macrophages. Conversely, re-expression of FOXN3 in macrophages stably expressing miR-708-5p could reverse the impact on macrophages. In addition, downregulation of FOXN3 by miR-708-5p in macrophages reduced their phagocytic capacity and increased the secretion of IL-10 and TGF-β. Interestingly, we found that cellular retention of miR-708-5p could inhibit the proliferation and promote the apoptosis of melanoma cells, suggesting the necessity for secretion of this microRNA. In summary, our findings provide novel insights into the mechanism of melanoma-derived miR-708-5p in facilitating the formation of an immunosuppressive tumor microenvironment and indicate the potential of miR-708-5p and FOXN3 as therapeutic targets for the treatment of melanoma.

The ability of cancer cells to promote cellular proliferation by preferentially using glycolysis as primary source of energy has long been considered a hallmark of tumour metabolism. However, emerging evidence suggests a more complex situation with many tumours exhibiting a pronounced dependence on mitochondrial respiration through oxidative phosphorylation (OXPHOS) for their development and maintenance. In line with this, numerous studies have reported an upregulation of mitochondrial genes and OXPHOS components across multiple cancer types. Glioblastoma (GBM) is the most frequent and malignant brain tumour in adults, characterised by rapid proliferation, resistance to therapy and ability to recur. In addition to a profound genetic and molecular heterogeneity, GBM also exhibits strong metabolic heterogeneity with different grades of dependence on mitochondrial activity. Notably, the transcription factor Nuclear Respiratory Factor 1 (NRF-1), a key regulator of OXPHOS gene expression and mitochondrial functions, has recently been linked to GBM progression and poor prognosis. Che-1/Apoptosis Antagonising Transcription Factor (AATF) is a transcriptional regulator with a crucial role in several cancer types, where it contributes to tumorigenesis by promoting cell cycle arrest and apoptosis, as well as resistance to therapy. Here, we show that AATF expression correlates with clinical outcome in GBM patients. Moreover, we demonstrate that its depletion leads to cell cycle arrest, impaired mitochondrial respiration and disrupted mitochondrial architecture in GBM cells. Additionally, AATF-depleted cells exhibit a reduced ability to form colonies in vitro and tumour in vivo. At the molecular level, we provide evidence that AATF interacts with NRF-1 and is essential for NRF-1-mediated transcription of the OXPHOS genes by affecting RNA polymerase II recruitment and chromatin structure. Overall, our findings highlight a previously unrecognised role of AATF in GBM proliferation and mitochondrial metabolism supporting its potential as a target for therapeutic intervention.

L-type amino acid transporter 1 (LAT1, encoded by Slc7a5) contributes to amino acid homeostasis and signaling in numerous cell types. Several lines of evidence implicate LAT1 in mammalian central nervous system development, but its functional significance in specific neuronal subtypes is largely unknown. Here, we demonstrate that LAT1/Slc7a5 expression in synapsin 1 (Syn1)-expressing neurons is essential for motor circuit development and motor coordination at the perinatal stage. Mice lacking Slc7a5 in Syn1-expressing neurons exhibited progressive motor coordination deficits and early postnatal lethality. These deficits were associated with selective degeneration of lower spinal motor neurons, reactive gliosis, skeletal muscle atrophy, and maldevelopment of neuromuscular junctions (NMJs), but no abnormalities in gross brain structure or neuronal viability. Pharmacological inhibition of apoptosis prolonged the survival of Slc7a5-deficient mice and reduced both lower motor neuron loss and NMJ maldevelopment. Furthermore, multi-cohort transcriptome analyses revealed inactivation of amino acid transport activity along with the downregulation of Slc7a5 expression in motor neurons of spinal muscular atrophy model mice. These results suggest that the amino acid transport system is essential for the survival and function of lower spinal motor neurons during early postnatal development, and identifies LAT1 as a potential therapeutic target for early-onset motor neuron diseases.

Dysregulation of alternative splicing is increasingly associated with cancer development and tumor progression. BCL2-associated transcription factor 1 (BCLAF1) is involved in a wide range of biological processes and it is continuously being investigated due to its intricate function in tumorigenesis and drug resistance. In acute myeloid leukemia (AML) cell lines, we identified two distinct, unbalanced isoforms of BCLAF1: the full-length isoform, which exhibits oncogenic properties, and the short-length isoform, which seems to act as a tumor suppressor. Treatment with specific epidrugs can re-establish the physiological balance of full- and short-length isoforms, restoring their correct equilibrium. Our results suggest the existence of a newly identified mechanism underlying the regulation of BCLAF1 splicing orchestrated, at least in part, by the interplay between HDAC1 and DNMT3A, and directly correlated with the healthy or cancerous state of hematopoietic cells. Our findings shed light on a novel regulatory axis in AML and highlight the potential of epidrugs to restore normal splicing patterns, paving the way for innovative therapies.

Metastatic gastric cancer (GC) has a poor prognosis. Recent research demonstrated the aberrant expression of nuclear receptor HNF4α and the regulatory roles of its isoforms during the processes of tumorigenesis and development. However, the expression patterns of HNF4α and its potential as a therapeutic target in metastatic GC remain elusive. In this study, we unveiled that P2 promoter-driven HNF4α (P2-HNF4α) was highly expressed in distant metastasis of GC, playing a pivotal role in fostering the migration and metastasis of GC cells both in vitro and in vivo. The transactivational activity was essential for HNF4α to promote GC cell migration. An integrative analysis of transcriptome and metabolome implied the involvement of the glycolytic pathway in the promotion of GC cell migration by P2-HNF4α. We further found that P2-HNF4α directly bound to the enhancer of the HKDC1 gene and upregulated its expression, thereby orchestrating a metabolic rewiring conducive to promoting GC migration and metastasis. Mycophenolic acid, an active metabolite of the FDA-approved drug mycophenolate mofetil, demonstrated the ability to suppress HKDC1 expression and GC migration and metastasis in vitro and in vivo through antagonizing HNF4α. Therefore, this study sheds light on the HNF4α-HKDC1 axis as a key player in GC metastasis, providing a promising targeted therapeutic strategy for metastatic GC.

Conventionally, KDM5C functions as a specific demethylase that targets histone H3 lysine 4 dimethyl and trimethyl modifications, crucial for gene expression. However, the role of KDM5C in multiple myeloma (MM) progression and bortezomib (BTZ) resistance has remained elusive. In this study, we found noncanonical functions of KDM5C in MM. Specifically, KDM5C binds to CBP and MYC, conferring BTZ resistance in MM through a demethylase-independent mechanism. Our investigations revealed that KDM5C is markedly upregulated in BTZ-resistant MM patients as well as those with relapsed MM. Significantly, the expression level of KDM5C exhibits an inverse correlation with the overall survival of MM patients. Moreover, KDM5C is indispensable for MM cell proliferation. Depletion of KDM5C augmented the sensitivity of MM cells to BTZ treatment both in vitro and in vivo. We found that KDM5C forms a novel complex with CBP and MYC via its PHD2 domain. This complex formation triggers lysine 27 acetylation in histone H3 (H3K27ac) and subsequent enrichment of H3K27ac on the PERK promoter. As a result, PERK transcription is activated, and Nrf2 phosphorylation is promoted, bolstering the unfolded protein response within the endoplasmic reticulum of MM cells. In contrast, the methylation status of histone H3 lysine 4 (H3K4me1/3) on the PERK promoter remains unaltered, regardless of the complex state. Taken together, the findings of this study underscore the key role of KDM5C as a driving force behind MM progression and BTZ resistance, indicating that KDM5C represents a novel and promising therapeutic target for the treatment of BTZ-resistant MM.

COVID-19 patients readily present with severe epithelial damage, such as tissue ulceration and erosion, along with disrupted tissue repair, in multiple organs. The mucous membranes of the lung alveoli [1, 2], gastrointestinal tract [3, 4], nasal [5] and oral cavity [6, 7] are the primary targets of the SARS-CoV-2 virus. The infected epithelium triggers a dysregulated immune response that further damages tissues and organs [8-10]. Increasing evidence suggests that the SARS-CoV-2 virus can cause direct damage to epithelial cells and fibroblasts [11-13]. Here, we report that the mucosa epithelia of COVID-19 patients can undergo cellular dedifferentiation before any pathological features are observed. SARS-CoV-2 nonspike structural proteins, particularly the Envelope protein, can rapidly induce epithelial cell dedifferentiation, micronuclei formation, cell cycle arrest at the G1 phase and apoptosis. The protein can also severely affect the progenitor cell stratification program. Mechanistically, we identified a unique molecule, calponin 2 (CNN2), as a downstream effector of nonspike structural proteins. Moreover, CNN2 levels were elevated in the epithelia of COVID-19 patients. Downregulating CNN2 could inhibit epithelial cell apoptosis and promote cell differentiation. CNN2 expression is negatively regulated by GLIS2, a transcription factor associated with the disruption of ciliary dynamics in epithelial cells. Therefore, we propose that SARS-CoV-2 damages mucosal epithelium integrity via a novel "double hijack" mechanism: inducing dedifferentiation and disrupting stratification and suggest a new therapeutic target: CNN2 for COVID-19 treatment.

Emerging evidence demonstrates the important role of ferroptosis, a novel regulated cell death, in the initiation and progression of acute kidney injury (AKI). However, the activation mechanism of ferroptosis in AKI has not been fully revealed. The pivotal function of interferon inducible protein 16 (IFI16) in DNA damage response (DDR) as DNA sensor and regulator of cell death pathways encouraged us to examine its role in ferroptosis of renal tubular epithelial cells (TECs) in AKI. Here we report that the levels of IFI16 and its mouse ortholog p204 were elevated in the kidney of patients with acute tubular necrosis (ATN) and in TECs of mice with renal ischemia/reperfusion (I/R)-induced AKI (I/R-AKI). Under I/R conditions, tubule-specific p204 deficiency in mice and IFI16 knockout in HK-2 cells significantly ameliorated TEC ferroptosis. Mechanistically, IFI16 binds to poly(ADP-ribose) polymerase 1 (PARP-1) and enhances protein Poly ADP-ribosylation (PARylation), which in turn potentiates the ataxia-telangiectasia mutated (ATM)-p53 signaling contributing to lipid peroxidation and ferrous ion accumulation in TECs. In addition, IFI16-amplified DDR was dependent on its HIN and PYRIN domains. Thus, our findings provide a better understanding of a critical pathogenic axis linking DNA damage to ferroptosis and suggest that targeting IFI16 may be an innovative therapeutic strategy for treating patients with AKI.