Cell Death Discovery
ISSN / EISSN : 2058-7716 / 2058-7716
Current Publisher: Springer Science and Business Media LLC (10.1038)Former Publisher:
Total articles ≅ 758
Latest articles in this journal
Cell Death Discovery, Volume 7, pp 1-15; doi:10.1038/s41420-021-00520-1
Phosphoglycerate kinase (PGK) is involved in glycolytic and various metabolic events. Dysfunction of PGK may induce metabolic reprogramming and the Warburg effect. In this study, we demonstrated that PGK1, but not PGK2, may play a key role in tumorigenesis and is associated with metastasis. We observed an inverse correlation between PGK1 and the survival rate in several clinical cohorts through bioinformatics statistical and immunohistochemical staining analyses. Surprisingly, we found that PGK1 was significantly increased in adenocarcinoma compared with other subtypes. Thus, we established a PGK1-based proteomics dataset by a pull-down assay. We further investigated HIV-1 Tat Specific Factor 1 (HTATSF1), a potential binding partner, through protein–protein interactions. Then, we confirmed that PGK1 indeed bound to HTATSF1 by two-way immunoprecipitation experiments. In addition, we generated several mutant clones of PGK1 through site-directed mutagenesis, including mutagenesis of the N-terminal region, the enzyme catalytic domain, and the C-terminal region. We observed that even though the phosphoglycerate kinase activity had been inhibited, the migration ability induced by PGK1 was maintained. Moreover, our immunofluorescence staining also indicated the translocation of PGK1 from the cytoplasm to the nucleus and its colocalization with HTATSF1. From the results presented in this study, we propose a novel model in which the PGK1 binds to HTATSF1 and exerts functional control of cancer metastasis. In addition, we also showed a nonenzymatic function of PGK1.
Cell Death Discovery, Volume 7, pp 1-13; doi:10.1038/s41420-021-00519-8
The mortality rate of ovarian cancer (OC) remains the highest among all gynecological malignancies. Platinum-based chemotherapies are effective in treating most OC cases. However, chemoresistance is still a major challenge for successful OC treatments. Emerging evidence has highlighted that the modulation of the tumor immune microenvironment is involved in chemoresistance, but the mechanism remains unclear. This study aimed to investigate whether resistance to cisplatin (CDDP), the standard treatment for OC, is due to the remodeling of the tumor immune microenvironment by the transcription factor EB (TFEB). We hypothesized that TFEB is not essential for tumor survival but is associated with CDDP resistance. We collected 20 tissue samples of OC patients who had not undergone chemotherapy or radiotherapy prior to surgery. We cultured OC cell lines and performed cell transfection and assays as well as analytical, fluorescence microscopy, and immunohistochemical techniques to explore a novel function of TFEB in remodeling the tumor immune microenvironment in OC. We found a positive correlation between TFEB and programmed cell death-ligand 1 (PD-L1), PD-L2, and HLA-A expression in OC cells and tissues. We also found that CDDP treatment induced TFEB nuclear translocation, thus increasing PD-L1 and PD-L2 expression to foster an immunosuppressive tumor microenvironment, which mediates tumor immune evasion and drug resistance. Interestingly, TFEB also regulated HLA-A expression, which increases the tumor immunogenicity of OC. Finally, in a syngenic murine model of OC, we observed the therapeutic benefit of CDDP plus programmed cell death-1 (PD-1) inhibitor, which enhanced the cytolytic activity of CD8+ T cells and inhibited tumor growth. Our study illustrates the important role of TFEB in regulating the tumor immune microenvironment in OC.
Cell Death Discovery, Volume 7, pp 1-15; doi:10.1038/s41420-021-00514-z
Inhibition of RhoA-ROCK pathway is involved in the H2S-induced cerebral vasodilatation and H2S-mediated protection on endothelial cells against oxygen-glucose deprivation/reoxygenation injury. However, the inhibitory mechanism of H2S on RhoA-ROCK pathway is still unclear. The aim of this study was to investigate the target and mechanism of H2S in inhibition of RhoA/ROCK. GST-RhoAwild and GST-RhoAS188A proteins were constructed and expressed, and were used for phosphorylation assay in vitro. Recombinant RhoAwild-pEGFP-N1 and RhoAS188A-pEGFP-N1 plasmids were constructed and transfected into primary hippocampal nerve cells (HNCs) to evaluate the neuroprotective mechanism of endothelial H2S by using transwell co-culture system with endothelial cells from cystathionine-γ-lyase knockout (CSE−/−) mice and 3-mercaptopyruvate sulfurtransferase knockout (3-MST−/−) rats, respectively. We found that NaHS, exogenous H2S donor, promoted RhoA phosphorylation at Ser188 in the presence of cGMP-dependent protein kinase 1 (PKG1) in vitro. Besides, both exogenous and endothelial H2S facilitated the RhoA phosphorylation at Ser188 in HNCs, which induced the reduction of RhoA activity and membrane transposition, as well as ROCK2 activity and expression. To further investigate the role of endothelial H2S on RhoA phosphorylation, we detected H2S release from ECs of CSE+/+ and CSE−/− mice, and 3-MST+/+ and 3-MST−/− rats, respectively, and found that H2S produced by ECs in the culture medium is mainly catalyzed by CSE synthase. Moreover, we revealed that both endothelial H2S, mainly catalyzed by CSE, and exogenous H2S protected the HNCs against hypoxia-reoxygenation injury via phosphorylating RhoA at Ser188.
Cell Death Discovery, Volume 7, pp 1-13; doi:10.1038/s41420-021-00511-2
Ovarian cancer is the most lethal gynecological cancer in the US. Standard treatment consists of surgery followed by chemotherapies relying on apoptotic tumor cell death. Most women with advanced stage disease will relapse, suggesting that this disease is characterized by primary and acquired resistance to chemotherapy, and novel approaches to treatment are greatly needed. Low Caspase 8 expression levels in ovarian cancers correlate with resistance to apoptotic chemotherapy, and a subpopulation of patients with low Caspase 8 levels exhibit poorer overall survival after standard-of-care treatment. We hypothesized that low Caspase 8 function reduces the ability of cancer cells to undergo apoptosis when exposed to standard chemotherapy and that second mitochondria-derived activator of caspases (Smac)-mimetics could increase cell death in combination with chemotherapy. Here we show that combination treatment with a Smac-mimetic can target tumor cells with low Caspase 8 and induce necroptotic cell death. We investigated the in vitro effect of Smac-mimetic added to carboplatin and paclitaxel treatment of ovarian cancer cells expressing wild type and low Caspase 8 levels, which resulted in a 2–4-fold enhancement of cell death. Mice bearing subcutaneous or intraperitoneal ovarian xenografts showed greater aggressiveness of Caspase 8-deficient versus wild-type tumors; combined in vivo treatment with chemotherapy and Smac-mimetic resulted in >50% decrease in low Caspase 8 xenograft growth, as well as significantly enhanced overall survival, especially when given simultaneously with paclitaxel. Surprisingly, Smac-mimetic on the same day as carboplatin decreased mouse survival compared to when it was given on a sequential day of treatment. The antagonism was associated with a decrease in DNA damage markers, emphasizing the importance of optimizing timing of drug administration. Clinical validation of such approaches is needed to increase the effectiveness of current standard ovarian cancer treatment.
Cell Death Discovery, Volume 7, pp 1-13; doi:10.1038/s41420-021-00521-0
Under adverse conditions, such as sustained or chronic hyperglycemia or hyperlipidemia, ROS (reactive oxygen species) or/and ER-stress (endoplasmic reticulum stress) will be induced in pancreatic β cells. ROS or ER-stress damages β-cells even leads to apoptosis. Previously we found ROS or ER-stress resulted in JNK activation in β cells and overexpressing NR4A1 in MIN6 cells reduced JNK activation via modulating cbl-b expression and subsequent degrading the upstream JNK kinase (MKK4). To search other possible mechanisms, we found the mRNA level and protein level of MKP7 (a phosphatase for phospho-JNK) were dramatic reduced in pancreatic β cells in the islets from NR4A1 KO mice compared with that from wild type mice. To confirm what we found in animals, we applied pancreatic β cells (MIN6 cells) and found that the expression of MKP7 was increased in NR4A1-overexpression MIN6 cells. We further found that knocking down the expression of MKP7 increased the p-JNK level in pancreatic β cells upon treatment with TG or H2O2. After that, we figured out that NR4A1 did enhance the transactivation of the MKP7 promoter by physical association with two putative binding sites. In sum, NR4A1 attenuates JNK phosphorylation incurred by ER-stress or ROS partially via enhancing MKP7 expression, potentially decreases pancreatic β cell apoptosis induced by ROS or ER-stress. Our finding provides a clue for diabetes prevention.
Cell Death Discovery, Volume 7, pp 1-15; doi:10.1038/s41420-021-00518-9
Altered protein homeostasis is associated with neurodegenerative diseases and acute brain injury induced under energy depletion conditions such as ischemia. The accumulation of damaged or unfolded proteins triggers the unfolded protein response (UPR), which can act as a homeostatic response or lead to cell death. However, the factors involved in turning and adaptive response into a cell death mechanism are still not well understood. Several mechanisms leading to brain injury induced by severe hypoglycemia have been described but the contribution of the UPR has been poorly studied. Cell responses triggered during both the hypoglycemia and the glucose reinfusion periods can contribute to neuronal death. Therefore, we have investigated the activation dynamics of the PERK and the IRE1α branches of the UPR and their contribution to neuronal death in a model of glucose deprivation (GD) and glucose reintroduction (GR) in cortical neurons. Results show a rapid activation of the PERK/p-eIF2α/ATF4 pathway leading to protein synthesis inhibition during GD, which contributes to neuronal adaptation, however, sustained blockade of protein synthesis during GR promotes neuronal death. On the other hand, IRE1α activation occurs early during GD due to its interaction with BAK/BAX, while ASK1 is recruited to IRE1α activation complex during GR promoting the nuclear translocation of JNK and the upregulation of Chop. Most importantly, results show that IRE1α RNase activity towards its splicing target Xbp1 mRNA occurs late after GR, precluding a homeostatic role. Instead, IRE1α activity during GR drives neuronal death by positively regulating ASK1/JNK activity through the degradation of 14-3-3 θ mRNA, a negative regulator of ASK and an adaptor protein highly expressed in brain, implicated in neuroprotection. Collectively, results describe a novel regulatory mechanism of cell death in neurons, triggered by the downregulation of 14-3-3 θ mRNA induced by the IRE1α branch of the UPR.
Cell Death Discovery, Volume 7, pp 1-11; doi:10.1038/s41420-021-00515-y
Chronic hepatitis B virus (HBV) infections remain a health burden affecting ~250 million people worldwide. Thus far, available interferon-alpha (IFNα)-based therapies have shown unsatisfactory cure rates, and alternative therapeutic molecules are still required. However, their development has been hampered because accessible cell models supporting relevant HBV replication and appropriate antiviral activity are lacking. Strategies that reverse epigenetic alterations offer a unique opportunity for cell reprogramming, which is valuable for restoring altered cellular functions in human cell lines. This work aimed to investigate the feasibility of converting HepG2 cells that stably overexpress the HBV entry receptor (sodium/taurocholate cotransporting polypeptide, NTCP) toward IFNα-responsive cells using epigenetic reprogramming. Herein, we showed that an epigenetic regimen with non-cytotoxic doses of the demethylating compound 5-azacytidine restored the anti-HBV action of IFNα in epigenetically reprogrammed HepG2-NTCP-C4 cells, named REP-HepG2-NTCP cells. Thus, a significant inhibition in HBV DNA levels was measured in REP-HepG2-NTCP cells after IFNα treatment. This inhibitory effect was associated with the enhancement of IFNα-mediated induction of critical interferon-stimulated genes (ISGs), which was limited in non-reprogrammed cells. In particular, our data indicated that re-expression of 2’-5’-oligoadenylate synthetase 1 (OAS1) and interferon regulatory factor 9 (IRF9) was the result of an epigenetically driven unmasking of these genes in reprogrammed cells. At last, we evaluated the therapeutic potential of the IFN analog CDM-3008 in REP-HepG2-NTCP cells and demonstrated the efficiency of this chemical compound in triggering ISG induction and HBV inhibition. In summary, this study shows that epigenetic reprogramming promotes the IFNα response in HBV-infected cells and is potentially attractive for cell-based experimental screening of IFN-like compounds.
Cell Death Discovery, Volume 7, pp 1-12; doi:10.1038/s41420-021-00494-0
Colorectal cancer (CRC) is the most common form of gastrointestinal malignancies. A growing number of reports focusing on oxaliplatin (OXA) resistance in CRC treatment have revealed that drug resistance is an urgent issue in clinical applications, especially for finding effective therapeutic targets. Recently, microRNAs (miRNAs) are reported to play a critical role in tumor progressions and multi-drug resistance. The main aim of this study is to establish whether miR-5000-3p is an oncogene that is resistant to OXA and further confirm its underlying regulatory role in CRC. The OXA-associated gene expression dataset in CRC cells was downloaded from Gene Expression Omnibus (GEO) database. Statistical software R was used for significance analysis of differentially expressed genes (DEGs) between OXA-resistant (OR)-CRC cells and CRC cells, and results indicated ubiquitin-specific peptidase 49 (USP49) was upregulated in OR-CRC cells. Luciferase reporter assay showed that USP49 was verified to act as a downstream target gene of miR-5000-3p. From the results of TCGA database, miR-5000-3p expression was upregulated and USP49 was downregulated in patients with CRC. The function of miR-5000-3p was detected using MTT assay, wound healing, Transwell, and flow cytometry assays. Moreover, through in vitro and in vivo experiments, miR-5000-3p expression was confirmed to be upregulated in CRC cells or OR-CRC cells comparing to normal cell lines. Molecular mechanism assays revealed that USP49 binds to the miR-5000-3p promoter to increase the expression of miR-5000-3p, resulting in cancer cells sensitized to OXA. To sum up, these results suggest that miR-5000-3p may be a novel biomarker involved in drug-resistance progression of CRC. Moreover, the drug-resistance mechanism of miR-5000-3p/USP49 axis provides new treatment strategies for CRC in clinical trials.
Cell Death Discovery, Volume 7; doi:10.1038/s41420-021-00513-0
Protein acetylation plays potential roles in regulating autophagy occurrence. However, it varies greatly between yeast and mammals, and has not been thoroughly investigated in other organisms. Here, we reported that the components of BmAtg8–PE ubiquitin-like system (BmAtg3, BmAtg4, BmAtg7, and BmAtg8) in Bombyx mori were localized in the nucleus under nutrient-rich conditions, whereas they were exported to the cytoplasm upon autophagy induction. RNAi of BmP300 and inhibition of BmP300 activity resulted in nucleo-cytoplasmic translocation of BmAtg3 and BmAtg8, as well as premature induction of autophagy in the absence of stimulus. Conversely, RNAi of BmHDAC1 and inhibition of class I/II HADCs activities led to the nuclear accumulation of BmAtg3 and BmAtg8. In addition, acetylation sites in Atg proteins of BmAtg8–PE ubiquitin-like system were identified by mass spectrometry, and acetylation-site mutations caused nucleo-cytoplasmic translocation of BmAtg3, BmAtg4, and BmAtg8 along with autophagy promotion. Similarly, the subcellular localization of human ATG4b is determined by acetylation modification. In general, BmP300-mediated acetylation sequesters the components of BmAtg8–PE ubiquitin-like system in the nucleus, thus leading to the autophagy inhibition. Oppositely, BmHDAC1-mediated deacetylation leads to the nucleo-cytoplasmic translocation of the components of BmAtg8–PE ubiquitin-like system and promotes autophagy. This process is evolutionarily conserved between insects and mammals.
Cell Death Discovery, Volume 7, pp 1-13; doi:10.1038/s41420-021-00510-3
Essential oils (EOs) have been recently emerging for their promising biological activities in preventing tumorigenesis or progression of different tumor histotypes, including melanoma. In this study, we investigated the antitumor activity of a panel of EOs in different tumor models. The ability of Melaleuca alternifolia (tea tree oil) and its main component, terpinen-4-ol, to sensitize the target therapy currently used for melanoma treatment was also assessed. Our results demonstrated that EOs differently affect the viability of human cancer cells and led us to select six EOs effective in melanoma and lung cancer cells, without toxic effects in human fibroblasts. When combined with dabrafenib and/or trametinib, Melaleuca alternifolia synergistically reduced the viability of melanoma cells by activating apoptosis. Through machine learning classification modeling, α-terpineol, tepinolene, and terpinen-4-ol, three components of Melaleuca alternifolia, were identified as the most likely relevant components responsible for the EO’s antitumor effect. Among them, terpinen-4-ol was recognized as the Melaleuca alternifolia component responsible for its antitumor and proapoptotic activity. Overall, our study holds promise for further analysis of EOs as new anticancer agents and supports the rationale for their use to improve target therapy response in melanoma.