The impact of acetylation and deacetylation on the p53 pathway. Protein Cell. 2011;2:456-462. [PMID: 21748595 DOI: 10.1007/s13238-011-1063-9]

Krüpple-like factors in cardiomyopathy: emerging player and therapeutic opportunities

Cardiomyopathy, a heterogeneous pathological condition characterized by changes in cardiac structure or function, represents a significant risk factor for the prevalence and mortality of cardiovascular disease (CVD). Research conducted over the years has led to the modification of definition and classification of cardiomyopathy. Herein, we reviewed seven of the most common types of cardiomyopathies, including Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), diabetic cardiomyopathy, Dilated Cardiomyopathy (DCM), desmin-associated cardiomyopathy, Hypertrophic Cardiomyopathy (HCM), Ischemic Cardiomyopathy (ICM), and obesity cardiomyopathy, focusing on their definitions, epidemiology, and influencing factors. Cardiomyopathies manifest in various ways ranging from microscopic alterations in cardiomyocytes, to tissue hypoperfusion, cardiac failure, and arrhythmias caused by electrical conduction abnormalities. As pleiotropic Transcription Factors (TFs), the Krüppel-Like Factors (KLFs), a family of zinc finger proteins, are involved in regulating the setting and development of cardiomyopathies, and play critical roles in associated biological processes, including Oxidative Stress (OS), inflammatory reactions, myocardial hypertrophy and fibrosis, and cellular autophagy and apoptosis, particularly in diabetic cardiomyopathy. However, research into KLFs in cardiomyopathy is still in its early stages, and the pathophysiologic mechanisms of some KLF members in various types of cardiomyopathies remain unclear. This article reviews the roles and recent research advances in KLFs, specifically those targeting and regulating several cardiomyopathy-associated processes.

Exposure to fluoride exacerbates the cognitive deficit of diabetic patients living in areas with endemic fluorosis, as well as of rats with type 2 diabetes induced by streptozotocin via a mechanism that may involve excessive activation of the poly(ADP ribose) polymerase-1/P53 pathway

Epidemiology has shown that fluoride exposure is associated with the occurrence of diabetes. However, whether fluoride affects diabetic encephalopathy is unclear. Elderly diabetic patients in areas with endemic (n = 169) or no fluorosis (108) and controls (85) underwent Montreal Cognitive Assessment. Sprague-Dawley rats receiving streptozotocin and/or different fluoride doses were examined for spatial learning and memory, brain morphology, blood-brain barrier, fasting blood glucose and insulin. Cultured SH-SY5Y cells were treated with 50 mM glucose and/or low- or high-dose fluoride, and P53-knockdown or poly-ADP-ribose polymerase-1 (PARP-1) inhibition. The levels of PARP-1, P53, poly-ADP-ribose (PAR), apoptosis-inducing factor (AIF), and phosphorylated-histone H2A.X (ser139) were measured by Western blotting. Reactive oxygen species (ROS), 8-hydroxydeguanosine (8-OHdG), PARP-1 activity, acetyl-P53, nicotinamide adenine dinucleotide (NAD+), activities of mitochondrial hexokinase1 (HK1) and citrate synthase (CS), mitochondrial membrane potential and apoptosis were assessed biochemically. Cognition of diabetic patients in endemic fluorosis areas was poorer than in other regions. In diabetic rats, fasting blood glucose, insulin resistance and blood-brain barrier permeability were elevated, while spatial learning and memory and Nissl body numbers in neurons declined. In these animals, expression and activity of P53 and PARP-1 and levels of NAD+, PAR, ROS, 8-OHdG, p-histone H2A.X (ser139), AIF and apoptosis content increased; whereas mitochondrial HK1 and CS activities and membrane potential decreased. SH-SY5Y cells exposed to glucose exhibited changes identical to diabetic rats. The changes in diabetic rats and cells treated with glucose were aggravated by fluoride. P53-knockout or PARP-1 inhibition mitigated the effects of glucose with/without low-dose fluoride. Elevation of diabetic encephalopathy was induced by exposure to fluoride and the underlying mechanism may involve overactivation of the PARP-1/P53 pathway.

Transgelin Promotes Glioblastoma Stem Cell Hypoxic Responses and Maintenance Through p53 Acetylation

Glioblastoma (GBM) is a lethal cancer characterized by hypervascularity and necrosis associated with hypoxia. Here, it is found that hypoxia preferentially induces the actin-binding protein, Transgelin (TAGLN), in GBM stem cells (GSCs). Mechanistically, TAGLN regulates HIF1α transcription and stabilizes HDAC2 to deacetylate p53 and maintain GSC self-renewal. To translate these findings into preclinical therapeutic paradigm, it is found that sodium valproate (VPA) is a specific inhibitor of TAGLN/HDAC2 function, with augmented efficacy when combined with natural borneol (NB) in vivo. Thus, TAGLN promotes cancer stem cell survival in hypoxia and informs a novel therapeutic paradigm.

Role of Histone Deacetylase 6 and Histone Deacetylase 6 Inhibition in Colorectal Cancer

Histone deacetylase 6 (HDAC6), by deacetylation of multiple substrates and association with interacting proteins, regulates many physiological processes that are involved in cancer development and invasiveness such as cell proliferation, apoptosis, motility, epithelial to mesenchymal transition, and angiogenesis. Due to its ability to remove misfolded proteins, induce autophagy, and regulate unfolded protein response, HDAC6 plays a protective role in responses to stress and enables tumor cell survival. The scope of this review is to discuss the roles of HDCA6 and its implications for the therapy of colorectal cancer (CRC). As HDAC6 is overexpressed in CRC, correlates with poor disease prognosis, and is not essential for normal mammalian development, it represents a good therapeutic target. Selective inhibition of HDAC6 impairs growth and progression without inducing major adverse events in experimental animals. In CRC, HDAC6 inhibitors have shown the potential to reduce tumor progression and enhance the therapeutic effect of other drugs. As HDAC6 is involved in the regulation of immune responses, HDAC6 inhibitors have shown the potential to improve antitumor immunity by increasing the immunogenicity of tumor cells, augmenting immune cell activity, and alleviating immunosuppression in the tumor microenvironment. Therefore, HDAC6 inhibitors may represent promising candidates to improve the effect of and overcome resistance to immunotherapy.

HDAC5-mediated exosomal Maspin and miR-151a-3p as biomarkers for enhancing radiation treatment sensitivity in hepatocellular carcinoma

BACKGROUND

Tumor-derived exosomes are critical elements of the cell-cell communication response to various stimuli. This study aims to reveal that the histone deacetylase 5 (HDAC5) and p53 interaction upon radiation in hepatocellular carcinoma intricately regulates the secretion and composition of exosomes.

METHODS

We observed that HDAC5 and p53 expression were significantly increased by 2 Gy and 4 Gy radiation exposure in HCC. Normal- and radiation-derived exosomes released by HepG2 were purified to investigate the exosomal components.

RESULTS

We found that in the radiation-derived exosome, exosomal Maspin was notably increased. Maspin is known as an anti-angiogenic gene. The expression of Maspin was regulated at the cellular level by HDAC5, and it was elaborately regulated and released in the exosome. Radiation-derived exosome treatment caused significant inhibition of angiogenesis in HUVECs and mouse aortic tissues. Meanwhile, we confirmed that miR-151a-3p was significantly reduced in the radiation-derived exosome through exosomal miRNA sequencing, and three HCC-specific exosomal miRNAs were also decreased. In particular, miR-151a-3p induced an anti-apoptotic response by inhibiting p53, and it was shown to induce EMT and promote tumor growth by regulating p53-related tumor progression genes. In the HCC xenograft model, radiation-induced exosome injection significantly reduced angiogenesis and tumor size.

CONCLUSIONS

Our present findings demonstrated HDAC5 is a vital gene of the p53-mediated release of exosomes resulting in tumor suppression through anti-cancer exosomal components in response to radiation. Finally, we highlight the important role of exosomal Maspin and mi-151a-3p as a biomarker in enhancing radiation treatment sensitivity. Therapeutic potential of HDAC5 through p53-mediated exosome modulation in radiation treatment of hepatocellular carcinoma.

Radioprotective efficacy of Astilbin in mitigating radiation-induced lung injury through inhibition of p53 acetylation

Radiation-induced lung injury (RILI) is a common side effect in thoracic tumor patients undergoing radiotherapy. At present, there is no ideal radio-protective agent which is widely used in RILI treatment. Astilbin (AST), a bioactive flavonoid, exhibits various biological effects, including anti-inflammatory, antioxidant, and anti-fibrotic activities, which partly result from reducing oxidative stress and inflammation in various pathogenic conditions. However, the protective efficacy of AST to ameliorate RILI has not been reported. In this study, we employed network pharmacology, RNA sequencing, and experimental evaluation to reveal the effects and pharmacological mechanism of AST to treat RILI in vivo and in vitro. We observed that AST reduced radiation-induced apoptosis, DNA damage, inflammatory reactions, and the reactive oxygen species (ROS) level in human normal lung epithelial cells BEAS-2B. Further study showed that AST treatment significantly ameliorated RILI by reducing the radiation-induced pathology changes and inflammatory reaction of lung tissue in C57BL/6J mice. Mechanistically, the expression of epithelial-mesenchymal transition (EMT) markers and radiation-triggered acetylation of the p53 protein were alleviated by AST treatment. Furthermore, AST alleviated the acetylation of p53 after intervention of Trichostatin A (TSA). Our data indicate that AST can alleviate RILI by inhibiting inflammatory reactions and the EMT process through decreasing the expression of p53 acetylation. In conclusion, our study suggests that AST has great potential to be a new protective and therapeutic compound for RILI.

A genomic perspective of the aging human and mouse lung with a focus on immune response and cellular senescence

BACKGROUND

The aging lung is a complex process and influenced by various stressors, especially airborne pathogens and xenobiotics. Additionally, a lifetime exposure to antigens results in structural and functional changes of the lung; yet an understanding of the cell type specific responses remains elusive. To gain insight into age-related changes in lung function and inflammaging, we evaluated 89 mouse and 414 individual human lung genomic data sets with a focus on genes mechanistically linked to extracellular matrix (ECM), cellular senescence, immune response and pulmonary surfactant, and we interrogated single cell RNAseq data to fingerprint cell type specific changes.

RESULTS

We identified 117 and 68 mouse and human genes linked to ECM remodeling which accounted for 46% and 27%, respectively of all ECM coding genes. Furthermore, we identified 73 and 31 mouse and human genes linked to cellular senescence, and the majority code for the senescence associated secretory phenotype. These cytokines, chemokines and growth factors are primarily secreted by macrophages and fibroblasts. Single-cell RNAseq data confirmed age-related induced expression of marker genes of macrophages, neutrophil, eosinophil, dendritic, NK-, CD4+, CD8+-T and B cells in the lung of aged mice. This included the highly significant regulation of 20 genes coding for the CD3-T-cell receptor complex. Conversely, for the human lung we primarily observed macrophage and CD4+ and CD8+ marker genes as changed with age. Additionally, we noted an age-related induced expression of marker genes for mouse basal, ciliated, club and goblet cells, while for the human lung, fibroblasts and myofibroblasts marker genes increased with age. Therefore, we infer a change in cellular activity of these cell types with age. Furthermore, we identified predominantly repressed expression of surfactant coding genes, especially the surfactant transporter Abca3, thus highlighting remodeling of surfactant lipids with implications for the production of inflammatory lipids and immune response.

CONCLUSION

We report the genomic landscape of the aging lung and provide a rationale for its growing stiffness and age-related inflammation. By comparing the mouse and human pulmonary genome, we identified important differences between the two species and highlight the complex interplay of inflammaging, senescence and the link to ECM remodeling in healthy but aged individuals.

ZNF500 abolishes breast cancer proliferation and sensitizes chemotherapy by stabilizing P53 via competing with MDM2

Zinc finger protein 500 (ZNF500) has an unknown expression pattern and biological function in human tissues. Our study revealed that the ZNF500 mRNA and protein levels were higher in breast cancer tissues than those in their normal counterparts. However, ZNF500 expression was negatively correlated with advanced TNM stage (p = 0.018), positive lymph node metastasis (p = 0.014), and a poor prognosis (p < 0.001). ZNF500 overexpression abolished in vivo and in vitro breast cancer cell proliferation by activating the p53-p21-E2F4 signaling axis and directly interacting with p53 via its C2H2 domain. This may prevent ubiquitination of p53 in a manner that is competitive to MDM2, thus stabilizing p53. When ZNF500-∆C2H2 was overexpressed, the suppressed proliferation of breast cancer cells was neutralized in vitro and in vivo. In human breast cancer tissues, ZNF500 expression was positively correlated with p53 (p = 0.022) and E2F4 (p = 0.004) expression. ZNF500 expression was significantly lower in patients with Miller/Payne Grade 1-2 than in those with Miller/Payne Grade 3-5 (p = 0.012). ZNF500 suppresses breast cancer cell proliferation and sensitizes cells to chemotherapy.

Biological Effects of HDAC Inhibitors Vary with Zinc Binding Group: Differential Effects on Zinc Bioavailability, ROS Production, and R175H p53 Mutant Protein Reactivation

The coordination of zinc by histone deacetylase inhibitors (HDACi), altering the bioavailability of zinc to histone deacetylases (HDACs), is key to HDAC enzyme inhibition. However, the ability of zinc binding groups (ZBGs) to alter intracellular free Zn+2 levels, which may have far-reaching effects, has not been explored. Using two HDACis with different ZBGs, we documented shifts in intracellular free Zn+2 concentrations that correlate with subsequent ROS production. Next, we assayed refolding and reactivation of the R175H mutant p53 protein in vitro to provide greater biological context as the activity of this mutant depends on cellular zinc concentration. The data presented demonstrates the differential activity of HDACi in promoting R175H response element (RE) binding. After cells are treated with HDACi, there are differences in R175H mutant p53 refolding and reactivation, which may be related to treatments. Collectively, we show that HDACis with distinct ZBGs differentially impact the intracellular free Zn+2 concentration, ROS levels, and activity of R175H; therefore, HDACis may have significant activity independent of their ability to alter acetylation levels. Our results suggest a framework for reevaluating the role of zinc in the variable or off-target effects of HDACi, suggesting that the ZBGs of HDAC inhibitors may provide bioavailable zinc without the toxicity associated with zinc metallochaperones such as ZMC1.

JNK1 activated pRb/E2F1 and inhibited p53/p21 signaling pathway is involved in hydroquinone-induced pathway malignant transformation of TK6 cells by accelerating the cell cycle progression

Hydroquinone (HQ) is an important metabolites of benzene in the body, and it has been found to result in cellular DNA damage, mutation, cell cycle imbalance, and malignant transformation. The JNK1 signaling pathway plays an important role in DNA damage repair. In this study, we focused on whether the JNK1 signaling pathway is involved in the HQ-induced cell cycle abnormalities and the underlying mechanism. The results showed that HQ induced abnormal progression of the cell cycle and initiated the JNK1 signaling pathway. We further confirmed that JNK1 suppression decelerated the cell cycle progression through inhibiting pRb/E2F1 signaling pathway and triggering p53/p21 pathway. Therefore, we concluded that JNK1 might be involved in HQ-induced malignant transformation associated with activating pRb/E2F1 and inhibiting p53/p21 signaling pathway which resulting in accelerating the cell cycle progression.

TRIB1 confers therapeutic resistance in GBM cells by activating the ERK and Akt pathways

GBM (Glioblastoma) is the most lethal CNS (Central nervous system) tumor in adults, which inevitably develops resistance to standard treatments leading to recurrence and mortality. TRIB1 is a serine/threonine pseudokinase which functions as a scaffold platform that initiates degradation of its substrates like C/EBPα through the ubiquitin proteasome system and also activates MEK and Akt signaling. We found that increased TRIB1 gene expression associated with worse overall survival of GBM patients across multiple cohorts. Importantly, overexpression of TRIB1 decreased RT/TMZ (radiation therapy/temozolomide)-induced apoptosis in patient derived GBM cell lines in vitro. TRIB1 directly bound to MEK and Akt and increased ERK and Akt phosphorylation/activation. We also found that TRIB1 protein expression was maximal during G2/M transition of cell cycle in GBM cells. Furthermore, TRIB1 bound directly to HDAC1 and p53. Importantly, mice bearing TRIB1 overexpressing tumors had worse overall survival. Collectively, these data suggest that TRIB1 induces resistance of GBM cells to RT/TMZ treatments by activating the cell proliferation and survival pathways thus providing an opportunity for developing new targeted therapeutics.

Acetylation halts missense mutant p53 aggregation and rescues tumor suppression in non-small cell lung cancers

TP53 mutations are ubiquitous with tumorigenesis in non-small cell lung cancers (NSCLC). By analyzing the TCGA database, we reported that TP53 missense mutations are correlated with chromosomal instability and tumor mutation burden in NSCLC. The inability of wild-type nor mutant p53 expression can't predict survival in lung cancer cohorts, however, an examination of primary NSCLC tissues found that acetylated p53 did yield an association with improved survival outcomes. Molecularly, we demonstrated that acetylation drove the ubiquitination and degradation of mutant p53 but enhanced stability of wild-type p53. Moreover, acetylation of a missense p53 mutation prevented the gain of oncogenic function observed in typical TP53 mutant-expressing cells and enhanced tumor suppressor functions. Consequently, acetylation inducer targeting of missense mutant p53 may be a viable therapeutic goal for NSCLC treatment and may improve the accuracy of current efforts to utilize p53 mutations in a prognostic manner.

Experimental Insights into the Interplay between Histone Modifiers and p53 in Regulating Gene Expression

Chromatin structure plays a fundamental role in regulating gene expression, with histone modifiers shaping the structure of chromatin by adding or removing chemical changes to histone proteins. The p53 transcription factor controls gene expression, binds target genes, and regulates their activity. While p53 has been extensively studied in cancer research, specifically in relation to fundamental cellular processes, including gene transcription, apoptosis, and cell cycle progression, its association with histone modifiers has received limited attention. This review explores the interplay between histone modifiers and p53 in regulating gene expression. We discuss how histone modifications can influence how p53 binds to target genes and how this interplay can be disrupted in cancer cells. This review provides insights into the complex mechanisms underlying gene regulation and their implications for potential cancer therapy.

KLF12 promotes the proliferation of breast cancer cells by reducing the transcription of p21 in a p53-dependent and p53-independent manner

Breast cancer is the most common cancer affecting women worldwide. Many genes are involved in the development of breast cancer, including the Kruppel Like Factor 12 (KLF12) gene, which has been implicated in the development and progression of several cancers. However, the comprehensive regulatory network of KLF12 in breast cancer has not yet been fully elucidated. This study examined the role of KLF12 in breast cancer and its associated molecular mechanisms. KLF12 was found to promote the proliferation of breast cancer and inhibit apoptosis in response to genotoxic stress. Subsequent mechanistic studies showed that KLF12 inhibits the activity of the p53/p21 axis, specifically by interacting with p53 and affecting its protein stability via influencing the acetylation and ubiquitination of lysine370/372/373 at the C-terminus of p53. Furthermore, KLF12 disrupted the interaction between p53 and p300, thereby reducing the acetylation of p53 and stability. Meanwhile, KLF12 also inhibited the transcription of p21 independently of p53. These results suggest that KLF12 might have an important role in breast cancer and serve as a potential prognostic marker and therapeutic target.

In silico analysis prediction of HepTH1-5 as a potential therapeutic agent by targeting tumour suppressor protein networks

Many studies reported that the activation of tumour suppressor protein, p53 induced the human hepcidin expression. However, its expression decreased when p53 was silenced in human hepatoma cells. Contrary to Tilapia hepcidin TH1-5, HepTH1-5 was previously reported to trigger the p53 activation through the molecular docking approach. The INhibitor of Growth (ING) family members are also shown to directly interact with p53 and promote cell cycle arrest, senescence, apoptosis and participate in DNA replication and DNA damage responses to suppress the tumour initiation and progression. However, the interrelation between INGs and HepTH1-5 remains unknown. Therefore, this study aims to identify the mechanism and their protein interactions using in silico approaches. The finding revealed that HepTH1-5 and its ligands had interacted mostly on hotspot residues of ING proteins which involved in histone modifications via acetylation, phosphorylation, and methylation. This proves that HepTH1-5 might implicate in an apoptosis signalling pathway and preserve the protein structure and function of INGs by reducing the perturbation of histone binding upon oxidative stress response. This study would provide theoretical guidance for the design and experimental studies to decipher the role of HepTH1-5 as a potential therapeutic agent for cancer therapy. Communicated by Ramaswamy H. Sarma.

A Brief Review on Chemoresistance; Targeting Cancer Stem Cells as an Alternative Approach

The acquisition of resistance to traditional chemotherapy and the chemoresistant metastatic relapse of minimal residual disease both play a key role in the treatment failure and poor prognosis of cancer. Understanding how cancer cells overcome chemotherapy-induced cell death is critical to improve patient survival rate. Here, we briefly describe the technical approach directed at obtaining chemoresistant cell lines and we will focus on the main defense mechanisms against common chemotherapy triggers by tumor cells. Such as, the alteration of drug influx/efflux, the enhancement of drug metabolic neutralization, the improvement of DNA-repair mechanisms, the inhibition of apoptosis-related cell death, and the role of p53 and reactive oxygen species (ROS) levels in chemoresistance. Furthermore, we will focus on cancer stem cells (CSCs), the cell population that subsists after chemotherapy, increasing drug resistance by different processes such as epithelial-mesenchymal transition (EMT), an enhanced DNA repair machinery, and the capacity to avoid apoptosis mediated by BCL2 family proteins, such as BCL-XL, and the flexibility of their metabolism. Finally, we will review the latest approaches aimed at decreasing CSCs. Nevertheless, the development of long-term therapies to manage and control CSCs populations within the tumors is still necessary.

Nuclear SPHK2/S1P induces oxidative stress and NLRP3 inflammasome activation via promoting p53 acetylation in lipopolysaccharide-induced acute lung injury

A bulk of evidence identified that macrophages, including resident alveolar macrophages and recruited macrophages from the blood, played an important role in the pathogenesis of acute respiratory distress syndrome (ARDS). However, the molecular mechanisms of macrophages-induced acute lung injury (ALI) by facilitating oxidative stress and inflammatory responses remain unclear. Herein, we noticed that the levels of mitochondrial reactive oxygen species (mtROS), SPHK2 and activated NLRP3 inflammasome were higher in peripheral blood mononuclear cells (PBMCs) of ARDS patients than that in healthy volunteers. Similar observations were recapitulated in LPS-treated RAW264.7 and THP-1 cells. After exposure to LPS, the SPHK2 enzymatic activity, NLRP3 inflammasome activation and mtROS were significantly upregulated in macrophages. Moreover, knockdown SPHK2 via shRNA or inhibition SPHK2 could prominently decrease LPS-induced M1 macrophage polarization, oxidative stress and NLRP3 inflammasome activation. Further study indicated that upregulated SPHK2 could increase nuclear sphingosine-1-phosphate (S1P) levels and then restrict the enzyme activity of HDACs to facilitate p53 acetylation. Acetylation of p53 reinforced its binding to the specific region of the NLRP3 promoter and drove expression of NLRP3. In the in vivo experiments, it was also observed that treating with Opaganib (ABC294640), a specific SPHK2 inhibitor, could observably alleviate LPS-induced ALI, evidencing by lowered infiltration of inflammatory cells, increased M2 macrophages polarization and reduced oxidative damage in lung tissues. Besides, SPHK2 inhibition can also decrease the accumulation of acetylated p53 protein and the activation of NLRP3 inflammasome. Taken together, our results demonstrated for the first time that nuclear S1P can regulate the acetylation levels of non-histone protein through affecting HDACs enzyme activities, linking them to oxidative stress and inflammation in response to environmental signals. These data provide a theoretical basis that SPHK2 may be an effective therapeutic target of ARDS.

Insights into Regulators of p53 Acetylation

The tumor suppressor p53 is a transcription factor that regulates the expression of dozens of target genes and diverse physiological processes. To precisely regulate the p53 network, p53 undergoes various post-translational modifications and alters the selectivity of target genes. Acetylation plays an essential role in cell fate determination through the activation of p53. Although the acetylation of p53 has been examined, the underlying regulatory mechanisms remain unclear and, thus, have attracted the interest of researchers. We herein discuss the role of acetylation in the p53 pathway, with a focus on p53 acetyltransferases and deacetylases. We also review recent findings on the regulators of these enzymes to understand the mode of p53 acetylation from a broader perspective.

Dynamic regulation of eEF1A1 acetylation affects colorectal carcinogenesis

The dysregulation of the translation elongation factor families which are responsible for reprogramming of mRNA translation has been shown to contribute to tumor progression. Here, we report that the acetylation of eukaryotic Elongation Factor 1 Alpha 1 (eEF1A1/EF1A1) is required for genotoxic stress response and maintaining the malignancy of colorectal cancer (CRC) cells. The evolutionarily conserved site K439 is identified as the key acetylation site. Tissue expression analysis demonstrates that the acetylation level of eEF1A1 K439 is higher than paired normal tissues. Most importantly, hyperacetylation of eEF1A1 at K439 negatively correlates with CRC patient survival. Mechanistically, CBP and SIRT1 are the major acetyltransferase and deacetylase of eEF1A1. Hyperacetylation of eEF1A1 at K439 shows a significant tumor-promoting effect by increasing the capacity of proliferation, migration, and invasion of CRC cells. Our findings identify the altered post-translational modification at the translation machines as a critical factor in stress response and susceptibility to colorectal carcinogenesis.

The Global research of protein post-translational modifications in the cancer field: A bibliometric and visualized study

Objectives

Protein post-translational modifications (PTMs) are closely associated with tumorigenesis, targeting PTMs of key proteins might be the focus of antitumor drug discovery. This study aimed to analyze the research progress on protein PTMs in tumorigenesis by performing qualitative and quantitative evaluations.

Methods

The Web of Science Core Collection was selected as the database, and Science Citation Index Expanded was selected as the citation index. Visualization tools such as VOSviewer, CiteSpace, HistCite, and Online Analysis Platform of Bibliometrics were used to deeply explore the information of the retrieved research papers and analyze them in terms of research trends and main aspects of research.

Results

The search yielded 3777 relevant articles. The results showed that the total number of PTMs related papers in cancer field has been increasing annually, with the largest number of papers published in the United States of America. The co-word cluster analysis showed that the research on PTMs and tumorigenesis was primarily focused on the following four areas, mechanism, histone, P53, key Technologies. Tumor metabolism, autophagy, and protein-protein interaction, histone ubiquitination have become new research topics.

Conclusion

This study provides an important reference for the research direction and selection of topics of interest in the PTMs of cancer field.

HDAC8-Selective Inhibition by PCI-34051 Enhances the Anticancer Effects of ACY-241 in Ovarian Cancer Cells

HDAC6 is overexpressed in ovarian cancer and is known to be correlated with tumorigenesis. Accordingly, ACY-241, a selective HDAC6 inhibitor, is currently under clinical trial and has been tested in combination with various drugs. HDAC8, another member of the HDAC family, has recently gained attention as a novel target for cancer therapy. Here, we evaluated the synergistic anticancer effects of PCI-34051 and ACY-241 in ovarian cancer. Among various ovarian cancer cells, PCI-34051 effectively suppresses cell proliferation in wild-type p53 ovarian cancer cells compared with mutant p53 ovarian cancer cells. In ovarian cancer cells harboring wild-type p53, PCI-34051 in combination with ACY-241 synergistically represses cell proliferation, enhances apoptosis, and suppresses cell migration. The expression of pro-apoptotic proteins is synergistically upregulated, whereas the expressions of anti-apoptotic proteins and metastasis-associated proteins are significantly downregulated in combination treatment. Furthermore, the level of acetyl-p53 at K381 is synergistically upregulated upon combination treatment. Overall, co-inhibition of HDAC6 and HDAC8 through selective inhibitors synergistically suppresses cancer cell proliferation and metastasis in p53 wild-type ovarian cancer cells. These results suggest a novel approach to treating ovarian cancer patients and the therapeutic potential in developing HDAC6/8 dual inhibitors.

Peptide and protein chemistry approaches to study the tumor suppressor protein p53

The tumor suppressor and master gene regulator protein p53 has been the subject of intense investigation for several decades due to its mutation in about half of all human cancers. However, mechanistic studies of p53 in cells are complicated by its many dynamic binding partners and heterogeneous post-translational modifications. The design of therapeutics that rescue p53 functions in cells requires a mechanistic understanding of its protein-protein interactions in specific protein complexes and identifying changes in p53 activity by diverse post-translational modifications. This review highlights the important roles that peptide and protein chemistry have played in biophysical and biochemical studies aimed at elucidating p53 regulation by several key binding partners. The design of various peptide inhibitors that rescue p53 function in cells and new opportunities in targeting p53-protein interactions are discussed. In addition, the review highlights the importance of a protein semisynthesis approach to comprehend the role of site-specific PTMs in p53 regulation.

Acetylation dependent translocation of EWSR1 regulates CHK2 alternative splicing in response to DNA damage

Ewing sarcoma breakpoint region 1 (EWSR1) is a member of FET (FUS/EWSR1/TAF15) RNA-binding family of proteins. The Ewing sarcoma oncoprotein EWS-FLI1 has been extensively studied, while much less is known about EWSR1 itself, especially the potential role of EWSR1 in response to DNA damage. Here, we found that UV irradiation induces acetylation of EWSR1, which is required for its nucleoli translocation. We identified K423, K432, K438, K640, and K643 as the major acetylation sites, p300/CBP and HDAC3/HDAC10 as the major acetyltransferases and deacetylases, respectively. Mechanically, UV-induced EWSR1 acetylation repressed its interaction with spliceosomal component U1C, which caused abnormal splicing of CHK2, suppressing the activity of CHK2 in response to UV irradiation. Taken together, our findings uncover acetylation as a novel regulatory modification of EWSR1, and is essential for its function in DNA damage response.

Post-translational Modifications of the p53 Protein and the Impact in Alzheimer's Disease: A Review of the Literature

Our understanding of Alzheimer's disease (AD) pathogenesis has developed with several hypotheses over the last 40 years, including the Amyloid and Tau hypotheses. More recently, the p53 protein, well-known as a genome guardian, has gained attention for its potential role in the early evolution of AD. This is due to the central involvement of p53's in the control of oxidative stress and potential involvement in the Amyloid and Tau pathways. p53 is commonly regulated by post-translational modifications (PTMs), which affect its conformation, increasing its capacity to adopt multiple structural and functional states, including those that can affect brain processes, thus contributing to AD development. The following review will explore the impact of p53 PTMs on its function and consequential involvement in AD pathogenesis. The greater understanding of the role of p53 in the pathogenesis of AD could result in more targeted therapies benefiting the many patients of this debilitating disease.

Selinexor improves the anti-cancer effect of tucidinostat on TP53 wild-type breast cancer

Histone deacetylase (HDAC) is closely related to the initiation and development of breast cancer (BC). Its inhibitor (HDACi) has been used to treat BC, while the efficacy of clinical trials was not reached expectations. HDACi combined with other drugs may be an effective strategy. This study explored the effect of HDACi tucidinostat combined with selinexor, an exportin 1 (XPO1) inhibitor, on ER⁺Her2^- BC cell lines of MCF-7 (wt-TP53), MDA-MB-175 (wt-TP53), MDA-MB-134 (mut-TP53) and T47D (mut-TP53) in vitro and cell derived xenografts (CDX) of MCF-7 in nude mice in vivo. Results showed that both tucidinostat and selinexor showed better inhibitory activities on wt-TP53 BC (MCF-7 and MDA-MB-175) comparing with mut-TP53 BC (MDA-MB-134 and T47D). Tucidinostat combined with selinexor significantly improved the effects of tucidinostat alone on the proliferation and invasion inhibitions and apoptosis promotions of MCF-7 and MDA-MB-175 cells in vitro. It also significantly enhanced the effects of tucidinostat on up-regulating the expression levels of acetyl-p53, nuclear p53, total p53, p21, Bax and Cleaved Caspase-3, and down-regulating the expression levels of Cyclin D1 and Bcl-2 in MCF-7 or MDA-MB-175 cells. Results consistent with in vitro were also obtained in CDX of MCF-7 in vivo. Taken together, we believe that tucidinostat and selinexor are potentially effective drug combinations for the treatment of wt-TP53 BC, and the molecular mechanism may be through enhancing the activity of p53 in the nucleus of BC cells to suppress proliferation and invasion and promote apoptosis.

The role of Siah2 in tumorigenesis and cancer therapy

Seven in absentia homolog 2 (Siah2), an RING E3 ubiquitin ligases, has been characterized to play the vital role in tumorigenesis and cancer progression. Numerous studies have determined that Siah2 promotes tumorigenesis in a variety of human malignancies such as prostate, lung, gastric, and liver cancers. However, several studies revealed that Siah2 exhibited tumor suppressor function by promoting the proteasome-mediated degradation of several oncoproteins, suggesting that Siah2 could exert its biological function according to different stages of tumor development. Moreover, Siah2 is subject to complex regulation, especially the phosphorylation of Siah2 by a variety of protein kinases to regulate its stability and activity. In this review, we describe the structure and regulation of Siah2 in human cancer. Moreover, we highlight the critical role of Siah2 in tumorigenesis. Furthermore, we note that the potential clinical applications of targeting Siah2 in cancer therapy.

The role of oxidative stress in intervertebral disc cellular senescence

With the aggravation of social aging and the increase in work intensity, the prevalence of spinal degenerative diseases caused by intervertebral disc degeneration(IDD)has increased yearly, which has driven a heavy economic burden on patients and society. It is well known that IDD is associated with cell damage and degradation of the extracellular matrix. In recent years, it has been found that IDD is induced by various mechanisms (e.g., genetic, mechanical, and exposure). Increasing evidence shows that oxidative stress is a vital activation mechanism of IDD. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) could regulate matrix metabolism, proinflammatory phenotype, apoptosis, autophagy, and aging of intervertebral disc cells. However, up to now, our understanding of a series of pathophysiological mechanisms of oxidative stress involved in the occurrence, development, and treatment of IDD is still limited. In this review, we discussed the oxidative stress through its mechanisms in accelerating IDD and some antioxidant treatment measures for IDD.

MDM2-Driven Ubiquitination Rapidly Removes p53 from Its Cognate Promoters

MDM2 is the principal antagonist of the tumor suppressor p53. p53 binds to its cognate DNA element within promoters and activates the transcription of adjacent genes. These target genes include MDM2. Upon induction by p53, the MDM2 protein binds and ubiquitinates p53, triggering its proteasomal degradation and providing negative feedback. This raises the question whether MDM2 can also remove p53 from its target promoters, and whether this also involves ubiquitination. In the present paper, we employ the MDM2-targeted small molecule Nutlin-3a (Nutlin) to disrupt the interaction of MDM2 and p53 in three different cancer cell lines: SJSA-1 (osteosarcoma), 93T449 (liposarcoma; both carrying amplified MDM2), and MCF7 (breast adenocarcinoma). Remarkably, removing Nutlin from the culture medium for less than five minutes not only triggered p53 ubiquitination, but also dissociated most p53 from its chromatin binding sites, as revealed by chromatin immunoprecipitation. This also resulted in reduced p53-responsive transcription, and it occurred much earlier than the degradation of p53 by the proteasome, arguing that MDM2 removes p53 from promoters prior to and thus independent of degradation. Accordingly, the short-term pharmacological inhibition of the proteasome did not alter the removal of p53 from promoters by Nutlin washout. However, when the proteasome inhibitor was applied for several hours, depleting non-conjugated ubiquitin prior to eliminating Nutlin, this compromised the removal of DNA-bound p53, as did an E1 ubiquitin ligase inhibitor. This suggests that the ubiquitination of p53 by MDM2 is necessary for its clearance from promoters. Depleting the MDM2 cofactor MDM4 in SJSA cells did not alter the velocity by that p53 was removed from promoters upon Nutlin washout. We conclude that MDM2 antagonizes p53 not only by covering its transactivation domain and by destabilization, but also by the rapid, ubiquitin-dependent termination of p53–chromatin interactions.

Protein acetylation effects on enzyme activity and metabolic pathway fluxes

Acetylation of proteins seems a widespread process found in the three domains of life. Several studies have shown that besides histones, acetylation of lysine residues also occurs in non-nuclear proteins. Hence, it has been suggested that this covalent modification is a mechanism that might regulate diverse metabolic pathways by modulating enzyme activity, stability, and/or subcellular localization or interaction with other proteins. However, protein acetylation levels seem to have low correlation with modification of enzyme activity and pathway fluxes. In addition, the results obtained with mutant enzymes that presumably mimic acetylation have frequently been over-interpreted. Moreover, there is a generalized lack of rigorous enzyme kinetic analysis in parallel to acetylation level determinations. The purpose of this review is to analyze the current findings on the impact of acetylation on metabolic enzymes and its repercussion on metabolic pathways function/regulation.

Profound changes in cerebrospinal fluid proteome and metabolic profile are associated with congenital hydrocephalus

The aetiology of congenital hydrocephalus (cHC) has yet to be resolved. cHC manifests late in rodent gestation, and by 18-22 weeks in human fetuses, coinciding with the start of the major phase of cerebral cortex development. Previously we found that cerebrospinal fluid (CSF) accumulation is associated with compositional changes, folate metabolic impairment and consequential arrest in cortical development. Here, we report a proteomics study on hydrocephalic and normal rat CSF using LC-MSMS and a metabolic pathway analysis to determine the major changes in metabolic and signalling pathways. Non-targeted analysis revealed a proteome transformation across embryonic days 17-20, with the largest changes between day 19 and 20. This provides evidence for a physiological shift in CSF composition and identifies some of the molecular mechanisms unleashed during the onset of cHC. Top molecular regulators that may control the shift in the CSF metabolic signature are also predicted, with potential key biomarkers proposed for early detection of these changes that might be used to develop targeted early therapies for this condition. This study confirms previous findings of a folate metabolic imbalance as well as providing more in depth metabolic analysis and understanding of cHC CSF.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

Engineered variants of the Ras effector protein RASSF5 (NORE1A) promote anticancer activities in lung adenocarcinoma

Within the superfamily of small GTPases, Ras appears to be the master regulator of such processes as cell cycle progression, cell division, and apoptosis. Several oncogenic Ras mutations at amino acid positions 12, 13, and 61 have been identified that lose their ability to hydrolyze GTP, giving rise to constitutive signaling and eventually development of cancer. While disruption of the Ras/effector interface is an attractive strategy for drug design to prevent this constitutive activity, inhibition of this interaction using small molecules is impractical due to the absence of a cavity to which such molecules could bind. However, proteins and especially natural Ras effectors that bind to the Ras/effector interface with high affinity could disrupt Ras/effector interactions and abolish procancer pathways initiated by Ras oncogene. Using a combination of computational design and in vitro evolution, we engineered high-affinity Ras-binding proteins starting from a natural Ras effector, RASSF5 (NORE1A), which is encoded by a tumor suppressor gene. Unlike previously reported Ras oncogene inhibitors, the proteins we designed not only inhibit Ras-regulated procancer pathways, but also stimulate anticancer pathways initiated by RASSF5. We show that upon introduction into A549 lung carcinoma cells, the engineered RASSF5 mutants decreased cell viability and mobility to a significantly greater extent than WT RASSF5. In addition, these mutant proteins induce cellular senescence by increasing acetylation and decreasing phosphorylation of p53. In conclusion, engineered RASSF5 variants provide an attractive therapeutic strategy able to oppose cancer development by means of inhibiting of procancer pathways and stimulating anticancer processes.

Mechanistic insights into p53-regulated cytotoxicity of combined entinostat and irinotecan against colorectal cancer cells

Late-stage colorectal cancer (CRC) is still a clinically challenging problem. The activity of the tumor suppressor p53 is regulated via post-translational modifications (PTMs). While the relevance of p53 C-terminal acetylation for transcriptional regulation is well defined, it is unknown whether this PTM controls mitochondrially mediated apoptosis directly. We used wild-type p53 or p53-negative human CRC cells, cells with acetylation-defective p53, transformation assays, CRC organoids, and xenograft mouse models to assess how p53 acetylation determines cellular stress responses. The topoisomerase-1 inhibitor irinotecan induces acetylation of several lysine residues within p53. Inhibition of histone deacetylases (HDACs) with the class I HDAC inhibitor entinostat synergistically triggers mitochondrial damage and apoptosis in irinotecan-treated p53-positive CRC cells. This specifically relies on the C-terminal acetylation of p53 by CREB-binding protein/p300 and the presence of C-terminally acetylated p53 in complex with the proapoptotic BCL2 antagonist/killer protein. This control of C-terminal acetylation by HDACs can mechanistically explain why combinations of irinotecan and entinostat represent clinically tractable agents for the therapy of p53-proficient CRC.

GET4 is a novel driver gene in colorectal cancer that regulates the localization of BAG6, a nucleocytoplasmic shuttling protein

Colorectal cancer (CRC) is one of the most common types of cancer and a significant cause of cancer mortality worldwide. Further improvements of CRC therapeutic approaches are needed. BCL2‐associated athanogene 6 (BAG6), a multifunctional scaffold protein, plays an important role in tumor progression. However, regulation of BAG6 in malignancies remains unclear. This study showed that guided entry of tail‐anchored proteins factor 4 (GET4), a component of the BAG6 complex, regulates the intercellular localization of BAG6 in CRC. Furthermore, GET4 was identified as a candidate driver gene on the short arm of chromosome 7, which is often amplified in CRC, by our bioinformatics approach using the CRC dataset from The Cancer Genome Atlas. Clinicopathologic and prognostic analyses using CRC datasets showed that GET4 was overexpressed in tumor cells due to an increased DNA copy number. High GET4 expression was an independent poor prognostic factor in CRC, whereas BAG6 was mainly overexpressed in the cytoplasm of tumor cells without gene alteration. The biological significance of GET4 was examined using GET4 KO CRC cells generated with CRISPR‐Cas9 technology or transfected CRC cells. In vitro and in vivo analyses showed that GET4 promoted tumor growth. It appears to facilitate cell cycle progression by cytoplasmic enrichment of BAG6‐mediated p53 acetylation followed by reduced p21 expression. In conclusion, we showed that GET4 is a novel driver gene and a prognostic biomarker that promotes CRC progression by inducing the cytoplasmic transport of BAG6. GET4 could be a promising therapeutic molecular target in CRC.

Epigenetic Alterations Upstream and Downstream of p53 Signaling in Colorectal Carcinoma

Colorectal cancer (CRC) belongs to the most common tumor types, and half of all CRC harbor missense mutations in the TP53 tumor suppressor gene. In addition to genetically caused loss of function of p53, epigenetic alterations (DNA methylation, histone modifications, micro-RNAs) contribute to CRC development. In this review, we focused on epigenetic alterations related to the entire p53 signaling pathway upstream and downstream of p53. Methylation of genes which activate p53 function has been reported, and methylation of APC and MGMT was associated with increased mutation rates of TP53. The micro-RNA 34a activates TP53 and was methylated in CRC. Proteins that regulate TP53 DNA methylation, mutations, and acetylation of TP53-related histones were methylated in CRC. P53 regulates the activity of numerous downstream proteins. Even if TP53 is not mutated, the function of wildtype p53 may be compromised if corresponding downstream genes are epigenetically inactivated. Thus, the role of p53 for CRC development, therapy response, and survival prognosis of patients may be much more eminent than previously estimated. Therefore, we propose that novel diagnostic devices measuring the entirety of genetic and epigenetic changes in the "p53 signalome" have the potential to improve the predictive and prognostic power in CRC diagnostics and management.

Arginine Methyltransferase PRMT1 Regulates p53 Activity in Breast Cancer

The protein p53 is one of the most important tumor suppressors, responding to a variety of stress signals. Mutations in p53 occur in about half of human cancer cases, and dysregulation of the p53 function by epigenetic modifiers and modifications is prevalent in a large proportion of the remainder. PRMT1 is the main enzyme responsible for the generation of asymmetric-dimethylarginine, whose upregulation or aberrant splicing has been observed in many types of malignancies. Here, we demonstrate that p53 function is regulated by PRMT1 in breast cancer cells. PRMT1 knockdown activated the p53 signal pathway and induced cell growth-arrest and senescence. PRMT1 could directly bind to p53 and inhibit the transcriptional activity of p53 in an enzymatically dependent manner, resulting in a decrease in the expression levels of several key downstream targets of the p53 pathway. We were able to detect p53 asymmetric-dimethylarginine signals in breast cancer cells and breast cancer tissues from patients, and the signals could be significantly weakened by silencing of PRMT1 with shRNA, or inhibiting PRMT1 activity with a specific inhibitor. Furthermore, PRMT1 inhibitors significantly impeded cell growth and promoted cellular senescence in breast cancer cells and primary tumor cells. These results indicate an important role of PRMT1 in the regulation of p53 function in breast tumorigenesis.

Interaction of Adenosine, Modified Using Carborane Clusters, with Ovarian Cancer Cells: A New Anticancer Approach against Chemoresistance

Platinum compounds remain the first-line drugs for the treatment of most lethal gynecological malignancies and ovarian cancers. Acquired platinum resistance remains a major challenge in gynecological oncology. Considering the unique physicochemical properties of the metallacarboranes modifier and the significant role of nucleoside derivatives as anticancer antimetabolites, we designed and synthesized a set of adenosine conjugates with metallacarboranes containing iron, cobalt, or chromium as semi-abiotic compounds that influence the cisplatin sensitivity of ovarian cancer cells. Adherent cultures of ovarian carcinoma cell lines and multicellular spheroids, ranging from sensitive to highly resistant including experimental cell lines "not responding" to platinum drugs were used. Iron-containing metallacarborane conjugates showed the best anticancer activity, especially against resistant cells. Compound modified at the C2' nucleoside position showed the best activity in resistant cancer cells and highly resistant cancer spheroids exposed to cisplatin, increasing cell cycle arrest, apoptosis or necrosis, and reactive oxygen species production. Moreover, it showed high cellular accumulation and did not induce cross-resistance to cisplatin, carboplatin, doxorubicin, paclitaxel, or gemcitabine in long-term cultures. The reference nido-carborane derivative (no metal ions) and unmodified nucleosides were not as effective. These findings indicate that metallacarborane modification of adenosine may sensitize ovarian cancer cells to cisplatin in combination treatment.

High Throughput miRNA Screening Identifies miR-574-3p Hyperproductive Effect in CHO Cells

CHO is the cell line of choice for the manufacturing of many complex biotherapeutics. The constant upgrading of cell productivity is needed to meet the growing demand for these life-saving drugs. Manipulation of small non-coding RNAs—miRNAs—is a good alternative to a single gene knockdown approach due to their post-transcriptional regulation of entire cellular pathways without posing translational burden to the production cell. In this study, we performed a high-throughput screening of 2042-human miRNAs and identified several candidates able to increase cell-specific and overall production of Erythropoietin and Etanercept in CHO cells. Some of these human miRNAs have not been found in Chinese hamster cells and yet were still effective in them. We identified miR-574-3p as being able, when overexpressed in CHO cells, to improve overall productivity of Erythropoietin and Etanercept titers from 1.3 to up to 2-fold. In addition, we validated several targets of miR-574-3p and identified p300 as a main target of miR-574-3p in CHO cells. Furthermore, we demonstrated that stable CHO cell overexpressing miRNAs from endogenous CHO pri-miRNA sequences outperform the cells with human pri-miRNA sequences. Our findings highlight the importance of flanking genomic sequences, and their secondary structure features, on pri-miRNA processing offering a novel, cost-effective and fast strategy as a valuable tool for efficient miRNAs engineering in CHO cells.

The Role of Post-Translational Acetylation and Deacetylation of Signaling Proteins and Transcription Factors after Cerebral Ischemia: Facts and Hypotheses

Histone deacetylase (HDAC) and histone acetyltransferase (HAT) regulate transcription and the most important functions of cells by acetylating/deacetylating histones and non-histone proteins. These proteins are involved in cell survival and death, replication, DNA repair, the cell cycle, and cell responses to stress and aging. HDAC/HAT balance in cells affects gene expression and cell signaling. There are very few studies on the effects of stroke on non-histone protein acetylation/deacetylation in brain cells. HDAC inhibitors have been shown to be effective in protecting the brain from ischemic damage. However, the role of different HDAC isoforms in the survival and death of brain cells after stroke is still controversial. HAT/HDAC activity depends on the acetylation site and the acetylation/deacetylation of the main proteins (c-Myc, E2F1, p53, ERK1/2, Akt) considered in this review, that are involved in the regulation of cell fate decisions. Our review aims to analyze the possible role of the acetylation/deacetylation of transcription factors and signaling proteins involved in the regulation of survival and death in cerebral ischemia.

Role of Dietary Antioxidants in p53-Mediated Cancer Chemoprevention and Tumor Suppression

Cancer arises through a complex interplay between genetic, behavioral, metabolic, and environmental factors that combined trigger cellular changes that over time promote malignancy. In terms of cancer prevention, behavioral interventions such as diet can promote genetic programs that may facilitate tumor suppression; and one of the key tumor suppressors responsible for initiating such programs is p53. The p53 protein is activated by various cellular events such as DNA damage, hypoxia, heat shock, and overexpression of oncogenes. Due to its role in cell fate decisions after DNA damage, regulatory pathways controlled by p53 help to maintain genome stability and thus “guard the genome” against mutations that cause cancer. Dietary intake of flavonoids, a C₁₅ group of polyphenols, is known to inhibit cancer progression and assist DNA repair through p53-mediated mechanisms in human cells via their antioxidant activities. For example, quercetin arrests human cervical cancer cell growth by blocking the G₂/M phase cell cycle and inducing mitochondrial apoptosis through a p53-dependent mechanism. Other polyphenols such as resveratrol upregulate p53 expression in several cancer cell lines by promoting p53 stability, which in colon cancer cells results in the activation of p53-mediated apoptosis. Finally, among vitamins, folic acid seems to play an important role in the chemoprevention of gastric carcinogenesis by enhancing gastric epithelial apoptosis in patients with premalignant lesions by significantly increased expression of p53. In this review, we discuss the role of these and other dietary antioxidants in p53-mediated cell signaling in relation to cancer chemoprevention and tumor suppression in normal and cancer cells.

Restoring NAD+ by NAMPT is essential for the SIRT1/p53-mediated survival of UVA- and UVB-irradiated epidermal keratinocytes

Nicotinamide adenine dinucleotide (NAD⁺) is a crucial coenzyme in energy production. The imbalance of NAD⁺ synthesis has been found to trigger age-related diseases, such as metabolic disorders, cancer, and neurodegenerative diseases. Also, UV irradiation induces NAD⁺ depletion in the skin. In mammals, nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme in the NAD⁺ salvage pathway and essential for NAD⁺ homeostasis. However, but few studies have focused on the role of NAMPT in response to UV irradiation. Here, we show that NAMPT prevents NAD⁺ depletion in epidermal keratinocytes to protect against the mild-dose UVA and UVB (UVA/B)-induced proliferation defects. We showed that poly(ADP-ribose) polymerase (PARP) inhibitor rescued the NAD⁺ depletion in UVA/B-irradiated human keratinocytes, confirming that PAPR transiently exhausts cellular NAD⁺ to repair DNA damage. Notably, the treatment with a NAMPT inhibitor exacerbated the UVA/B-induced loss of energy production and cell viability. Moreover, the NAMPT inhibitor abrogated the sirtuin-1 (SIRT1)-mediated deacetylation of p53 and significantly inhibited the proliferation of UVA/B-irradiated cells, suggesting that the NAMPT-NAD⁺-SIRT1 axis regulates p53 functions upon UVA/B stress. The supplementation with NAD⁺ intermediates, nicotinamide mononucleotide and nicotinamide riboside, rescued the UVA/B-induced phenotypes in the absence of NAMPT activity. Therefore, NAD⁺ homeostasis is likely essential for the protection of keratinocytes from UV stress in mild doses. Since the skin is continuously exposed to UVA/B irradiation, understanding the protective role of NAMPT in UV stress will help prevent and treat skin photoaging.

Emerging roles of non-histone protein crotonylation in biomedicine

Crotonylation of proteins is a newly found type of post-translational modifications (PTMs) which occurs leadingly on the lysine residue, namely, lysine crotonylation (Kcr). Kcr is conserved and is regulated by a series of enzymes and co-enzymes including lysine crotonyltransferase (writer), lysine decrotonylase (eraser), certain YEATS proteins (reader), and crotonyl-coenzyme A (donor). Histone Kcr has been substantially studied since 2011, but the Kcr of non-histone proteins is just an emerging field since its finding in 2017. Recent advances in the identification and quantification of non-histone protein Kcr by mass spectrometry have increased our understanding of Kcr. In this review, we summarized the main proteomic characteristics of non-histone protein Kcr and discussed its biological functions, including gene transcription, DNA damage response, enzymes regulation, metabolic pathways, cell cycle, and localization of heterochromatin in cells. We further proposed the performance of non-histone protein Kcr in diseases and the prospect of Kcr manipulators as potential therapeutic candidates in the diseases.

The p53 pathway in vasculature revisited: A therapeutic target for pathological vascular remodeling?

Pathological vascular remodeling contributes to the development of restenosis following intraluminal interventions, transplant vasculopathy, and pulmonary arterial hypertension. Activation of the tumor suppressor p53 may counteract vascular remodeling by inhibiting aberrant proliferation of vascular smooth muscle cells and repressing vascular inflammation. In particular, the development of different lines of small-molecule p53 activators ignites the hope of treating remodeling-associated vascular diseases by targeting p53 pharmacologically. In this review, we discuss the relationships between p53 and pathological vascular remodeling, and summarize current experimental data suggesting that drugging the p53 pathway may represent a novel strategy to prevent the development of vascular remodeling.

Mechanoresponsive Smad5 Enhances MiR-487a Processing to Promote Vascular Endothelial Proliferation in Response to Disturbed Flow

MicroRNAs (miRs) and bone morphogenetic protein receptor-specific Smads are mechano-responsive molecules that play vital roles in modulating endothelial cell (EC) functions in response to blood flow. However, the roles of interplay between these molecules in modulating EC functions under flows remain unclear. We elucidated the regulatory roles of the interplay between miR-487a and Smad5 in EC proliferation in response to different flow patterns. Microarray and quantitative RT-PCR showed that disturbed flow with low and oscillatory shear stress (OS, 0.5 ± 4 dynes/cm²) upregulates EC miR-487a in comparison to static controls and pulsatile shear stress (12 ± 4 dynes/cm²). MiR-487a expression was higher in ECs in the inner curvature (OS region) than the outer curvature of the rat aortic arch and thoracic aorta and also elevated in diseased human coronary arteries. MiR-487a expression was promoted by nuclear phospho-Smad5, which bound to primary-miR-487a to facilitate miR-487a processing. Algorithm prediction and luciferase reporter and argonaute 2-immunoprecipitation assays demonstrated that miR-487a binds to 3'UTR of CREB binding protein (CBP) and p53. Knockdown and overexpression of miR-487a decreased and increased, respectively, phospho-Rb and cyclin A expressions through CBP and p53. A BrdU incorporation assay showed that miR-487a enhanced EC proliferation under OS in vitro and in disturbed flow regions of experimentally stenosed rat abdominal aorta in vivo. These results demonstrate that disturbed flow with OS induces EC expression of miR-487a through its enhanced processing by activated-Smad5. MiR-487 inhibits its direct targets CBP and p53 to induce EC cycle progression and proliferation. Our findings suggest that EC miR-487 may serve as an important molecular target for intervention against disturbed flow-associated vascular disorders resulting from atherosclerosis.

Negative Regulation of SIRT1 by IRF9 Involved in Hyperlipidemia Acute Pancreatitis Associated with Kidney Injury

BACKGROUND

Interferon regulatory factor 9 (IRF9) acts as a negative regulator of sirtuin-1 (SIRT1) to participate in many diseases. However, the role of SIRT1 and IRF9 in hyperlipidemia acute pancreatitis associated with kidney injury is unclear.

AIMS

To explore the function of SIRT1 and IRF9 in hyperlipidemia acute pancreatitis associated with kidney injury and provide theoretical guidance for disease diagnosis and treatment.

METHODS

Model rats were established by intraperitoneal injection of 20% L-arginine. Apoptosis of kidney tissue was determined by TUNEL staining. Expressions of IRF9, SIRT1, p53, and acetylated p53 were detected by qRT-PCR and Western blot. Dual-Luciferase Reporter Assay was carried out to validate the regulation of IRF9 on SIRT1.

RESULTS

Pancreatic and renal injury was more serious, and apoptosis of kidney epithelial cells increased in acute pancreatitis (AP) and hyperlipidemia acute pancreatitis (HLAP) group. IRF9, p53, and acetylated p53 were up-regulated, and SIRT1 was down-regulated in AP and HLAP group (p < 0.05). Down-regulation of SIRT1 was negatively correlated with up-regulation of IRF9 in AP and HLAP group (p < 0.05). Pancreatic and renal injury and kidney epithelial cells apoptosis in HLAP group were more obvious than AP group (p < 0.05). The up-regulation of IRF9 and down-regulation of SIRT1 in HLAP group were more than AP group (p < 0.05). The promoter activity of SIRT1 was repressed by IRF9.

CONCLUSION

In pancreatitis associated with kidney injury, IRF9 was a negative regulator of SIRT1, down-regulated the expression of SIRT1, increased acetylated p53, and promoted renal cell apoptosis. Hyperlipidemia further aggravated pancreatic and renal injury and renal cell apoptosis.

Development and validation of the TGx-HDACi transcriptomic biomarker to detect histone deacetylase inhibitors in human TK6 cells

Transcriptomic biomarkers can be used to inform molecular initiating and key events involved in a toxicant's mode of action. To address the limited approaches available for identifying epigenotoxicants, we developed and assessed a transcriptomic biomarker of histone deacetylase inhibition (HDACi). First, we assembled a set of ten prototypical HDACi and ten non-HDACi reference compounds. Concentration-response experiments were performed for each chemical to collect TK6 human lymphoblastoid cell samples after 4 h of exposure and to assess cell viability following a 20-h recovery period in fresh media. One concentration was selected for each chemical for whole transcriptome profiling and transcriptomic signature derivation, based on cell viability at the 24-h time point and on maximal induction of HDACi-response genes (RGL1, NEU1, GPR183) or cellular stress-response genes (ATF3, CDKN1A, GADD45A) analyzed by TaqMan qPCR assays after 4 h of exposure. Whole transcriptomes were profiled after 4 h exposures by Templated Oligo-Sequencing (TempO-Seq). By applying the nearest shrunken centroid (NSC) method to the whole transcriptome profiles of the reference compounds, we derived an 81-gene toxicogenomic (TGx) signature, referred to as TGx-HDACi, that classified all 20 reference compounds correctly using NSC classification and the Running Fisher test. An additional 4 HDACi and 7 non-HDACi were profiled and analyzed using TGx-HDACi to further assess classification performance; the biomarker accurately classified all 11 compounds, including 3 non-HDACi epigenotoxicants, suggesting a promising specificity toward HDACi. The availability of TGx-HDACi increases the diversity of tools that can facilitate mode of action analysis of toxicants using gene expression profiling.

Ubiquitin-conjugating enzyme E2T(UBE2T) promotes colorectal cancer progression by facilitating ubiquitination and degradation of p53

OBJECTIVES

The expression level of Ubiquitin-conjugating enzyme E2T (UBE2T) is upregulated in various types of human tumors. We explored the correlation and regulatory mechanism of UBE2T in the development of colorectal cancer (CRC).

METHODS

Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to examine the expression of UBE2T in the CRC tissues and cell lines. Immunohistochemical staining, spearman correlation analysis, and Kaplan Meier-survival analysis were used to demonstrate the correlation between UBE2T high expression level and the clinical characteristics of malignant patients and the overall survival. The proliferation, apoptosis, migration and invasion of CRC cells were analyzed by cell transfection, MTT, colony formation, scratch assay, transwell, and flow cytometry. Furthermore, the expression of cell proliferation and apoptosis related proteins and ubiquitination of p53 were detected by western blot.

RESULTS

UBE2T was up-regulated in CRC tissues and cell lines, and high expression level of UBE2T was correlated with the clinical characteristics of malignant of CRC patients (P<0.05), and patients with high expression level of UBE2T had lower overall survival (P=0.0455). In addition, UBE2T could promote the growth, proliferation, invasion and metastasis of CRC cells and inhibit the apoptosis. At the same time, knockdown of UBE2T inhibited the growth of transplanted tumor in mice of subcutaneous CRC model. Moreover, our experimental results proved that UBE2T regulated the expression of downstream related proteins through ubiquitination of p53 protein to promote the occurrence and development of CRC.

CONCLUSION

Our study elucidated that high expression of UBE2T would enhance the development of CRC, and then further explored its molecular mechanism both in vitro and in vivo. The results indicated that UBE2T facilitated ubiquitination and degradation of p53, which predicts the possibility of UBE2T as one of molecular diagnosis markers, prognostic indicators and therapeutic drug targets of CRC patients.

Emerging roles of SIRT6 in human diseases and its modulators

The biological functions of sirtuin 6 (SIRT6; e.g., deacetylation, defatty-acylation, and mono-ADP-ribosylation) play a pivotal role in regulating lifespan and several fundamental processes controlling aging such as DNA repair, gene expression, and telomeric maintenance. Over the past decades, the aberration of SIRT6 has been extensively observed in diverse life-threatening human diseases. In this comprehensive review, we summarize the critical roles of SIRT6 in the onset and progression of human diseases including cancer, inflammation, diabetes, steatohepatitis, arthritis, cardiovascular diseases, neurodegenerative diseases, viral infections, renal and corneal injuries, as well as the elucidation of the related signaling pathways. Moreover, we discuss the advances in the development of small molecule SIRT6 modulators including activators and inhibitors as well as their pharmacological profiles toward potential therapeutics for SIRT6-mediated diseases.

TRIM47 promotes malignant progression of renal cell carcinoma by degrading P53 through ubiquitination

Background

Renal cell carcinoma (RCC) is one of the most common malignant tumors originating from the renal parenchymal urinary epithelial system. Tripartite motif 47 (TRIM47) is a member of the TRIM family proteins, which has E3 ligase activity and has been demonstrated to be involved in the occurrence and prognosis of many tumors. The main purpose of this study is to explore the role and potential mechanism of TRIM47 in promoting malignant biological behavior of RCC.

Materials and methods

TRIM47 mRNA and protein levels in human renal cancer and paired normal adjacent tissues were detected by qRT-PCR and Western blot. The effects of TRIM47 knockdown and overexpression in renal cell carcinoma cells on cell proliferation, invasion and xenograft tumor growth in nude mice were analyzed. The molecular mechanism was explored by mass spectrometric exploration,Western blot and immunoprecipitation assays.

Results

TRIM47 promoted RCC cell proliferation in vitro and in vivo as an oncogene. Mechanistically, TRIM47 exerted an E3 ligase activity by interacting with P53 protein to increase its ubiquitination and degradation, which further promoted the malignant biological behavior of RCC.

Conclusions

Our study demonstrated that the TRIM47-P53 axis played a functional role in RCC progression and suggested a potential therapeutic target for RCC.

Signal Transducer and Activator of Transcription 3 (STAT3) Suppresses STAT1/Interferon Signaling Pathway and Inflammation in Senescent Preadipocytes

Obesity promotes premature aging and dysfunction of white adipose tissue (WAT) through the accumulation of cellular senescence. The senescent cells burden in WAT has been linked to inflammation, insulin-resistance (IR), and type 2 diabetes (T2D). There is limited knowledge about molecular mechanisms that sustain inflammation in obese states. Here, we describe a robust and physiologically relevant in vitro system to trigger senescence in mouse 3T3-L1 preadipocytes. By employing transcriptomics analyses, we discovered up-regulation of key pro-inflammatory molecules and activation of interferon/signal transducer and activator of transcription (STAT)1/3 signaling in senescent preadipocytes, and expression of downstream targets was induced in epididymal WAT of obese mice, and obese human adipose tissue. To test the relevance of STAT1/3 signaling to preadipocyte senescence, we used Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein 9 (CRISPR/Cas9) technology to delete STAT1/3 and discovered that STAT1 promoted growth arrest and cooperated with cyclic Guanosine Monophosphate-Adenosine Monophosphate (GMP-AMP) synthase-stimulator of interferon genes (cGAS-STING) to drive the expression of interferon β (IFNβ), C-X-C motif chemokine ligand 10 (CXCL10), and interferon signaling-related genes. In contrast, we discovered that STAT3 was a negative regulator of STAT1/cGAS-STING signaling-it suppressed senescence and inflammation. These data provide insights into how STAT1/STAT3 signaling coordinates senescence and inflammation through functional interactions with the cGAS/STING pathway.