Regulation of the p53 response and its relationship to cancer

miR-10a as a therapeutic target and predictive biomarker for MDM2 inhibition in acute myeloid leukemia

Pharmacological inhibition of MDM2/4, which activates the critical tumor suppressor p53, has been gaining increasing interest as a strategy for the treatment of acute myeloid leukemia (AML). While clinical trials of MDM2 inhibitors have shown promise, responses have been confined to largely molecularly undefined patients, indicating that new biomarkers and optimized treatment strategies are needed. We previously reported that the microRNA miR-10a is strongly overexpressed in some AML, and demonstrate here that it modulates several key members of the p53/Rb network, including p53 regulator MDM4, Rb regulator RB1CC1, p21 regulator TFAP2C, and p53 itself. The expression of both miR-10a and its downstream targets were strongly predictive of MDM2 inhibitor sensitivity in cell lines, primary AML specimens, and correlated to response in patients treated with both MDM2 inhibitors and cytarabine. Furthermore, miR-10a inhibition induced synergy between MDM2 inhibitor Nutlin-3a and cytarabine in both in vitro and in vivo AML models. Mechanistically this synergism primarily occurs via the p53-mediated activation of cytotoxic apoptosis at the expense of cytoprotective autophagy. Together these findings demonstrate that miR-10a may be useful as both a biomarker to identify patients most likely to respond to cytarabine+MDM2 inhibition and also a druggable target to increase their efficacy.

Single Cell Detection of the p53 Protein by Mass Cytometry

Simple Summary

Investigation of protein expression in cancer cells is an important part of the diagnostic process. Increasing knowledge about expression of different proteins has been exploited for prognostic assessments and in some cases also for selection of treatment. The p53 protein has proven important in development of various cancers, and the expression of this protein and its signaling pathway is therefore of interest when examining cancer patient samples. Here, we present mass cytometry as a tool for detection of p53 expression. Mass cytometry allows for measurement of up to 50 parameters per sample with single cell resolution, and we aim to demonstrate its potential for p53-focused research.

Abstract

Purpose: The p53 protein and its post-translational modifications are distinctly expressed in various normal cell types and malignant cells and are usually detected by immunohistochemistry and flow cytometry in contemporary diagnostics. Here, we describe an approach for simultaneous multiparameter detection of p53, its post-translational modifications and p53 pathway-related signaling proteins in single cells using mass cytometry. Method: We conjugated p53-specific antibodies to metal tags for detection by mass cytometry, allowing the detection of proteins and their post-translational modifications in single cells. We provide an overview of the antibody validation process using relevant biological controls, including cell lines treated in vitro with a stimulus (irradiation) known to induce changes in the expression level of p53. Finally, we present the potential of the method through investigation of primary samples from leukemia patients with distinct TP53 mutational status. Results: The p53 protein can be detected in cell lines and in primary samples by mass cytometry. By combining antibodies for p53-related signaling proteins with a surface marker panel, we show that mass cytometry can be used to decipher the single cell p53 signaling pathway in heterogeneous patient samples. Conclusion: Single cell profiling by mass cytometry allows the investigation of the p53 functionality through examination of relevant downstream signaling proteins in normal and malignant cells. Our work illustrates a novel approach for single cell profiling of p53.

Dysregulation of lysophospholipid signaling by p53 in malignant cells and the tumor microenvironment

The TP53 gene has been widely studied for its roles in cell cycle control, maintaining genome stability, activating repair mechanisms upon DNA damage, and initiating apoptosis should repair mechanisms fail. Thus, it is not surprising that mutations of p53 are the most common genetic alterations found in human cancer. Emerging evidence indicates that dysregulation of lipid metabolism by p53 can have a profound impact not only on cancer cells but also cells of the tumor microenvironment (TME). In particular, intermediates of the sphingolipid and lysophospholipid pathways regulate many cellular responses common to p53 such as cell survival, migration, DNA damage repair and apoptosis. The majority of these cellular events become dysregulated in cancer as well as cell senescence. In this review, we will provide an account on the seminal contributions of Prof. Lina Obeid, who deciphered the crosstalk between p53 and the sphingolipid pathway particularly in modulating DNA damage repair and apoptosis in non-transformed as well as transformed cells. We will also provide insights on the integrative role of p53 with the lysophosphatidic acid (LPA) signaling pathway in cancer progression and TME regulation.

AMG900 as novel inhibitor of the translationally controlled tumor protein

INTRODUCTION

Cancer is one of the leading causes of death worldwide. Classical cytotoxic chemotherapy exerts high side effects and low tumor selectivity. Translationally controlled tumor protein (TCTP) is a target for differentiation therapy, a promising, new therapeutic approach, which is expected to be more selective and less toxic than cytotoxic chemotherapy. The aim of the present investigation was to identify novel TCTP inhibitors.

METHODS

We performed in silico screening and molecular docking using a chemical library of more than 31,000 compounds to identify a novel inhibitor of TCTP. We tested AMG900 in vitro for binding to TCTP by microscale thermophoresis and co-immunoprecipitation. Additionally, we examined the effect of TCTP blockade on cell cycle progression by flow cytometry and Western blotting and cancer cell survival by resazurin assays in MCF-7, SK-OV3 and MOLT-4 cell lines.

RESULTS

We identified AMG900 as new inhibitor of TCTP. AMG900 bound to the p53 binding site of TCTP with a free binding energy of -9.63 ± 0.01 kcal/mol. This compound decreased TCTP expression to 23.4 ± 1.59% and increased p53 expression to 194.29 ± 24.27%. Furthermore, AMG900 induced G0/G1 arrest as shown by flow cytometry and Western blot of relevant cell cycle proteins. AMG900 decreased CDK2, CDK4, CDK6, cyclin D1 and cyclin D3 expression, whereas p18, p21 and p27 expression increased. Moreover, AMG900 disturbed TCTP-p53 complexation as shown by co-immunoprecipitation and increased expression of free p53.

DISCUSSION

AMG900 may serve as novel lead compound for the development of differentiation therapy approaches against cancer.

Berberine Inhibits Cell Proliferation by Interfering with Wild-Type and Mutant P53 in Human Glioma Cells

Introduction

Glioma is the most common malignant brain tumor. TP53 is the most common mutant gene in human cancer. Wild-type p53 (wtp53) is a tumor suppressor protein whereas mutant p53 (mutp53) is an oncoprotein that promotes tumor cell proliferation. Our aim was to examine the inhibitory effects of berberine on the proliferation of human glioma cells via regulation of wtp53, mutp53, and their downstream molecules.

Methods

We selected wtp53 cells (U87 cells) and mutp53 cells (U251 cells termed p53 R273H) to examine the inhibitory effects of berberine on human glioma cells. We used the CCK-8 kit to detect the toxic effect of berberine. Flow cytometry was used to detect the effect of berberine. Clone formation test was used to test the inhibitory effect of berberine on the proliferation of glioma cells. Western blot was used to detect the changes of related proteins such as p53, p-p53, p21 and cyclin D1. Lentivirus transduction was used to transduce wild-type p53 into U251 cells to further examine the effect of berberine. The nude mouse subcutaneous tumor model was used to detect the effect of berberine on inhibiting the proliferation of glioma cells in vivo.

Results

Berberine promoted the phosphorylation of wtp53, increased the expression of p21 protein, reduced cyclin D1 content, and caused G1 phase arrest in U87 cells. Berberine also reduced mutp53 content and caused G2 phase arrest in U251 cells with a concurrent decrease in p21, cyclin D1, and cyclin B1 content. Transduction with wtp53 enhanced the effects on cell cycle arrest. Further, berberine significantly inhibited glioma growth in vivo mouse tumor model.

Discussion

Glioma is a group of heterogeneous brain tumors with unique biological and clinical characteristics. Berberine can inhibit glioma cells through a variety of ways. Our research indicated that berberine inhibited the proliferation of glioma cells by interfering with wtp53 and mutp53. This indicates that berberine could be used as a potential drug to treat wild-type and mutant p53 glioma.

Integrative p53, micro-RNA and Cathepsin Protease Co-Regulatory Expression Networks in Cancer

Simple Summary

This article describes an emerging area of significant interest in cancer and cell death and the relationships shared by these through the transcriptional regulation of cathepsin protease genes by micro-RNAs that are connected to p53 activation. While it has been demonstrated that the p53 protein can directly regulate some cathepsin genes and the expression of their upstream regulatory micro-RNAs, very little is known about what input the p53 isoform proteins may have in regulating this relationship. Herein, we draw attention to this important regulatory aspect in the context of describing mechanisms that are being established for the micro-RNA regulation of cathepsin protease genes and their collective use in diagnostic or prognostic assays.

Abstract

As the direct regulatory role of p53 and some of its isoform proteins are becoming established in modulating gene expression in cancer research, another aspect of this mode of gene regulation that has captured significant interest over the years is the mechanistic interplay between p53 and micro-RNA transcriptional regulation. The input of this into modulating gene expression for some of the cathepsin family members has been viewed as carrying noticeable importance based on their biological effects during normal cellular homeostasis and cancer progression. While this area is still in its infancy in relation to general cathepsin gene regulation, we review the current p53-regulated micro-RNAs that are generating significant interest through their regulation of cathepsin proteases, thereby strengthening the link between activated p53 forms and cathepsin gene regulation. Additionally, we extend our understanding of this developing relationship to how such micro-RNAs are being utilized as diagnostic or prognostic tools and highlight their future uses in conjunction with cathepsin gene expression as potential biomarkers within a clinical setting.

The Δ133p53 Isoforms, Tuners of the p53 Pathway

Simple Summary

TP53, the most frequently mutated gene in human cancers, has a key role in the maintenance of the genetic stability and, thus, in preventing tumor development. The p53-dependent responses were long thought to be solely driven by canonical p53α. However, it is now known that TP53 physiologically expresses at least 12 p53 isoforms including Δ133p53α, Δ133p53β and Δ133p53γ. The Δ133p53 isoforms are potent modulators of the p53 pathway that regulate critical functions in cancer, physiological and premature aging, neurodegenerative diseases, immunity and inflammation, and tissue repair. This review aims to summarize the current knowledge on the Δ133p53 isoforms and how they contribute to multiple physiological and pathological mechanisms. Critically, further characterization of p53 isoforms may identify novel regulatory modes of p53 pathway functions that contribute to disease progression and facilitate the development of new therapeutic strategies.

Abstract

The TP53 gene is a critical tumor suppressor and key determinant of cell fate which regulates numerous cellular functions including DNA repair, cell cycle arrest, cellular senescence, apoptosis, autophagy and metabolism. In the last 15 years, the p53 pathway has grown in complexity through the discovery that TP53 differentially expresses twelve p53 protein isoforms in human cells with both overlapping and unique biologic activities. Here, we summarize the current knowledge on the Δ133p53 isoforms (Δ133p53α, Δ133p53β and Δ133p53γ), which are evolutionary derived and found only in human and higher order primates. All three isoforms lack both of the transactivation domains and the beginning of the DNA-binding domain. Despite the absence of these canonical domains, the Δ133p53 isoforms maintain critical functions in cancer, physiological and premature aging, neurodegenerative diseases, immunity and inflammation, and tissue repair. The ability of the Δ133p53 isoforms to modulate the p53 pathway functions underscores the need to include these p53 isoforms in our understanding of how the p53 pathway contributes to multiple physiological and pathological mechanisms. Critically, further characterization of p53 isoforms may identify novel regulatory modes of p53 pathway functions that contribute to disease progression and facilitate the development of new therapeutic strategies.

Autophagic feedback-mediated degradation of IKKα requires CHK1- and p300/CBP-dependent acetylation of p53

In our previous report, we demonstrated that one of the catalytic subunits of the IκB kinase (IKK) complex, IKKα (encoded by CHUK), performs an NF-κB-independent cytoprotective role in human hepatoma cells under the treatment of the anti-tumor therapeutic reagent arsenite. IKKα triggers its own degradation, as a feedback loop, by activating p53-dependent autophagy, and therefore contributes substantially to hepatoma cell apoptosis induced by arsenite. Interestingly, IKKα is unable to interact with p53 directly but plays a critical role in mediating p53 phosphorylation (at Ser15) by promoting CHK1 activation and CHK1-p53 complex formation. In the current study, we found that p53 acetylation (at Lys373 and/or Lys382) was also critical for the induction of autophagy and the autophagic degradation of IKKα during the arsenite response. Furthermore, IKKα was involved in p53 acetylation through interaction with the acetyltransferases for p53, p300 (also known as EP300) and CBP (also known as CREBBP) (collectively p300/CBP), inducing CHK1-dependent p300/CBP activation and promoting p300-p53 or CBP-p53 complex formation. Therefore, taken together with the previous report, we conclude that both IKKα- and CHK1-dependent p53 phosphorylation and acetylation contribute to mediating selective autophagy feedback degradation of IKKα during the arsenite-induced proapoptotic responses.

Emerging Evidences for an Implication of the Neurodegeneration-Associated Protein TAU in Cancer

Neurodegenerative disorders and cancer may appear unrelated illnesses. Yet, epidemiologic studies indicate an inverse correlation between their respective incidences for specific cancers. Possibly explaining these findings, increasing evidence indicates that common molecular pathways are involved, often in opposite manner, in the pathogenesis of both disease families. Genetic mutations in the MAPT gene encoding for TAU protein cause an inherited form of frontotemporal dementia, a neurodegenerative disorder, but also increase the risk of developing cancer. Assigning TAU at the interface between cancer and neurodegenerative disorders, two major aging-linked disease families, offers a possible clue for the epidemiological observation inversely correlating these human illnesses. In addition, the expression level of TAU is recognized as a prognostic marker for cancer, as well as a modifier of cancer resistance to chemotherapy. Because of its microtubule-binding properties, TAU may interfere with the mechanism of action of taxanes, a class of chemotherapeutic drugs designed to stabilize the microtubule network and impair cell division. Indeed, a low TAU expression is associated to a better response to taxanes. Although TAU main binding partners are microtubules, TAU is able to relocate to subcellular sites devoid of microtubules and is also able to bind to cancer-linked proteins, suggesting a role of TAU in modulating microtubule-independent cellular pathways associated to oncogenesis. This concept is strengthened by experimental evidence linking TAU to P53 signaling, DNA stability and protection, processes that protect against cancer. This review aims at collecting literature data supporting the association between TAU and cancer. We will first summarize the evidence linking neurodegenerative disorders and cancer, then published data supporting a role of TAU as a modifier of the efficacy of chemotherapies and of the oncogenic process. We will finish by addressing from a mechanistic point of view the role of TAU in de-regulating critical cancer pathways, including the interaction of TAU with cancer-associated proteins.

The Regulation of Ferroptosis by Tumor Suppressor p53 and its Pathway

Tumor suppressor p53 plays a key role in tumor suppression. In addition to tumor suppression, p53 is also involved in many other biological and pathological processes, such as immune response, maternal reproduction, tissue ischemia/reperfusion injuries and neurodegenerative diseases. While it has been widely accepted that the role of p53 in regulation of cell cycle arrest, senescence and apoptosis contributes greatly to the function of p53 in tumor suppression, emerging evidence has implicated that p53 also exerts its tumor suppressive function through regulation of many other cellular processes, such as metabolism, anti-oxidant defense and ferroptosis. Ferroptosis is a unique iron-dependent form of programmed cell death driven by lipid peroxidation in cells. Ferroptosis has been reported to be involved in cancer, tissue ischemia/reperfusion injuries and neurodegenerative diseases. Recent studies have shown that ferroptosis can be regulated by p53 and its signaling pathway as well as tumor-associated mutant p53. Interestingly, the regulation of ferroptosis by p53 appears to be highly context-dependent. In this review, we summarize recent advances in the regulation of ferroptosis by p53 and its signaling pathway. Further elucidation of the role and molecular mechanism of p53 in ferroptosis regulation will yield new therapeutic strategies for cancer and other diseases, including neurodegenerative diseases and tissue ischemia/reperfusion injuries.

P53 vs NF-κB: the role of nuclear factor-kappa B in the regulation of p53 activity and vice versa

The onco-suppressor p53 is a transcription factor that regulates a wide spectrum of genes involved in various cellular functions including apoptosis, cell cycle arrest, senescence, autophagy, DNA repair and angiogenesis. p53 and NF-κB generally have opposing effects in cancer cells. While p53 activity is associated with apoptosis induction, the stimulation of NF-κB has been demonstrated to promote resistance to programmed cell death. Although the transcription factor NF-κB family is considered as the master regulator of cancer development and maintenance, it has been mainly studied in relation to its ability to regulate p53. This has revealed the importance of the crosstalk between NF-κB, p53 and other crucial cell signaling pathways. This review analyzes the various mechanisms by which NF-κB regulates the activity of p53 and the role of p53 on NF-κB activity.

Effect of 1α,25(OH)2 Vitamin D3 in Mutant P53 Glioblastoma Cells: Involvement of Neutral Sphingomyelinase1

Glioblastoma is one the most aggressive primary brain tumors in adults, and, despite the fact that radiation and chemotherapy after surgical approaches have been the treatments increasing the survival rates, the prognosis of patients remains poor. Today, the attention is focused on highlighting complementary treatments that can be helpful in improving the classic therapeutic approaches. It is known that 1α,25(OH)2 vitamin D3, a molecule involved in bone metabolism, has many serendipidy effects in cells. It targets normal and cancer cells via genomic pathway by vitamin D3 receptor or via non-genomic pathways. To interrogate possible functions of 1α,25(OH)2 vitamin D3 in multiforme glioblastoma, we used three cell lines, wild-type p53 GL15 and mutant p53 U251 and LN18 cells. We demonstrated that 1α,25(OH)2 vitamin D3 acts via vitamin D receptor in GL15 cells and via neutral sphingomyelinase1, with an enrichment of ceramide pool, in U251 and LN18 cells. Changes in sphingomyelin/ceramide content were considered to be possibly responsible for the differentiating and antiproliferative effect of 1α,25(OH)2 vitamin D in U251 and LN18 cells, as shown, respectively, in vitro by immunofluorescence and in vivo by experiments of xenotransplantation in eggs. This is the first time 1α,25(OH)2 vitamin D3 is interrogated for the response of multiforme glioblastoma cells in dependence on the p53 mutation, and the results define neutral sphingomyelinase1 as a signaling effector.

RBM10, a New Regulator of p53

The tumor suppressor p53 acts as a transcription factor that regulates the expression of a number of genes responsible for DNA repair, cell cycle arrest, metabolism, cell migration, angiogenesis, ferroptosis, senescence, and apoptosis. It is the most commonly silenced or mutated gene in cancer, as approximately 50% of all types of human cancers harbor TP53 mutations. Activation of p53 is detrimental to normal cells, thus it is tightly regulated via multiple mechanisms. One of the recently identified regulators of p53 is RNA-binding motif protein 10 (RBM10). RBM10 is an RNA-binding protein frequently deleted or mutated in cancer cells. Its loss of function results in various deformities, such as cleft palate and malformation of the heart, and diseases such as lung adenocarcinoma. In addition, RBM10 mutations are frequently observed in lung adenocarcinomas, colorectal carcinomas, and pancreatic ductal adenocarcinomas. RBM10 plays a regulatory role in alternative splicing. Several recent studies not only linked this splicing regulation of RBM10 to cancer development, but also bridged RBM10's anticancer function to the p53 pathway. This review will focus on the current progress in our understanding of RBM10 regulation of p53, and its role in p53-dependent cancer prevention.

ODiNPred: comprehensive prediction of protein order and disorder

Structural disorder is widespread in eukaryotic proteins and is vital for their function in diverse biological processes. It is therefore highly desirable to be able to predict the degree of order and disorder from amino acid sequence. It is, however, notoriously difficult to predict the degree of local flexibility within structured domains and the presence and nuances of localized rigidity within intrinsically disordered regions. To identify such instances, we used the CheZOD database, which encompasses accurate, balanced, and continuous-valued quantification of protein (dis)order at amino acid resolution based on NMR chemical shifts. To computationally forecast the spectrum of protein disorder in the most comprehensive manner possible, we constructed the sequence-based protein order/disorder predictor ODiNPred, trained on an expanded version of CheZOD. ODiNPred applies a deep neural network comprising 157 unique sequence features to 1325 protein sequences together with the experimental NMR chemical shift data. Cross-validation for 117 protein sequences shows that ODiNPred better predicts the continuous variation in order along the protein sequence, suggesting that contemporary predictors are limited by the quality of training data. The inclusion of evolutionary features reduces the performance gap between ODiNPred and its peers, but analysis shows that it retains greater accuracy for the more challenging prediction of intermediate disorder.

Reactivation of Epstein-Barr Virus by HIF-1α Requires p53

We previously reported that the cellular transcription factor hypoxia-inducible factor 1α (HIF-1α) binds a hypoxia response element (HRE) located within the promoter of Epstein-Barr virus's (EBV's) latent-lytic switch BZLF1 gene, Zp, inducing viral reactivation. In this study, EBV-infected cell lines derived from gastric cancers and Burkitt lymphomas were incubated with HIF-1α-stabilizing drugs: the iron chelator deferoxamine (Desferal [DFO]), a neddylation inhibitor (pevonedistat [MLN-4924]), and a prolyl hydroxylase inhibitor (roxadustat [FG-4592]). DFO and MLN-4924, but not FG-4592, induced accumulation of both lytic EBV proteins and phosphorylated p53 in cell lines that contain a wild-type p53 gene. FG-4592 also failed to activate transcription from Zp in a reporter assay despite inducing accumulation of HIF-1α and transcription from another HRE-containing promoter. Unexpectedly, DFO failed to induce EBV reactivation in cell lines that express mutant or no p53 or when p53 expression was knocked down with short hairpin RNAs (shRNAs). Likewise, HIF-1α failed to activate transcription from Zp when p53 was knocked out by CRISPR-Cas9. Importantly, DFO induced binding of p53 as well as HIF-1α to Zp in chromatin immunoprecipitation (ChIP) assays, but only when the HRE was present. Nutlin-3, a drug known to induce accumulation of phosphorylated p53, synergized with DFO and MLN-4924 in inducing EBV reactivation. Conversely, KU-55933, a drug that inhibits ataxia telangiectasia mutated, thereby preventing p53 phosphorylation, inhibited DFO-induced EBV reactivation. Lastly, activation of Zp transcription by DFO and MLN-4924 mapped to its HRE. Thus, we conclude that induction of BZLF1 gene expression by HIF-1α requires phosphorylated, wild-type p53 as a coactivator, with HIF-1α binding recruiting p53 to Zp.IMPORTANCE EBV, a human herpesvirus, is latently present in most nasopharyngeal carcinomas, Burkitt lymphomas, and some gastric cancers. To develop a lytic-induction therapy for treating patients with EBV-associated cancers, we need a way to efficiently reactivate EBV into lytic replication. EBV's BZLF1 gene product, Zta, usually controls this reactivation switch. We previously showed that HIF-1α binds the BZLF1 gene promoter, inducing Zta synthesis, and HIF-1α-stabilizing drugs can induce EBV reactivation. In this study, we determined which EBV-positive cell lines are reactivated by classes of HIF-1α-stabilizing drugs. We found, unexpectedly, that HIF-1α-stabilizing drugs only induce reactivation when they also induce accumulation of phosphorylated, wild-type p53. Fortunately, p53 phosphorylation can also be provided by drugs such as nutlin-3, leading to synergistic reactivation of EBV. These findings indicate that some HIF-1α-stabilizing drugs may be helpful as part of a lytic-induction therapy for treating patients with EBV-positive malignancies that contain wild-type p53.

Inhibition of Specificity Protein 1 Is Involved in Phloretin-Induced Suppression of Prostate Cancer

Phloretin is a flavonoid existed in various plants and has been reported to possess anticarcinogenic activity. However, the anticancer mechanism of phloretin in prostate cancer (PCa) remains unclear. Here, our in vitro and in vivo experimental data demonstrate that phloretin inhibits the phosphorylation and the activation of EGFR and then inhibits its downstream PI3K/AKT and MEK/ERK1/2 pathways in PCa cells. Inhibition of these two pathways further decreases expression of Sp1 by inhibiting Sp1 gene transcription, induces degradation of Sp1 protein by inhibiting GSK3β phosphorylation, suppresses nucleolin-enhanced translation of Sp1 mRNA by inhibiting nucleolin phosphorylation, and directly inactivates transcription activity of Sp1. Inhibition of Sp1 subsequently decreases the expression of Sp3/4, VEGF, and Survivin and then upregulates apoptosis-related proteins and downregulates cell cycle-related proteins in PCa cells. Finally, phloretin treatment in PCa cells induces cell growth inhibition and apoptosis, suggesting that phloretin may be an effective therapy compound in the treatment of prostate cancer.

Tumor suppressor p53 cross-talks with TRIM family proteins

p53 is a key tumor suppressor. As a transcription factor, p53 accumulates in cells in response to various stress signals and selectively transcribes its target genes to regulate a wide variety of cellular stress responses to exert its function in tumor suppression. In addition to tumor suppression, p53 is also involved in many other physiological and pathological processes, e.g. anti-infection, immune response, development, reproduction, neurodegeneration and aging. To maintain its proper function, p53 is under tight and delicate regulation through different mechanisms, particularly the posttranslational modifications. The tripartite motif (TRIM) family proteins are a large group of proteins characterized by the RING, B-Box and coiled-coil (RBCC) domains at the N-terminus. TRIM proteins play important roles in regulation of many fundamental biological processes, including cell proliferation and death, DNA repair, transcription, and immune response. Alterations of TRIM proteins have been linked to many diseases including cancer, infectious diseases, developmental disorders, and neurodegeneration. Interestingly, recent studies have revealed that many TRIM proteins are involved in the regulation of p53, and at the same time, many TRIM proteins are also regulated by p53. Here, we review the cross-talk between p53 and TRIM proteins, and its impact upon cellular biological processes as well as cancer and other diseases.

Cytosolic NUAK1 Enhances ATP Production by Maintaining Proper Glycolysis and Mitochondrial Function in Cancer Cells

NUAK1 is an AMPK-related kinase located in the cytosol and the nucleus, whose expression associates with tumor malignancy and poor patient prognosis in several cancers. Accordingly, NUAK1 was associated with metastasis because it promotes cell migration and invasion in different cancer cells. Besides, NUAK1 supports cancer cell survival under metabolic stress and maintains ATP levels in hepatocarcinoma cells, suggesting a role in energy metabolism in cancer. However, the underlying mechanism for this metabolic function, as well as its link to NUAK1 subcellular localization, is unclear. We demonstrated that cytosolic NUAK1 increases ATP levels, which associates with increased mitochondrial respiration, supporting that cytosolic NUAK1 is involved in mitochondrial function regulation in cancer cells. NUAK1 inhibition led to the formation of “donut-like” structures, providing evidence of NUAK1-dependent mitochondrial morphology regulation. Additionally, our results indicated that cytosolic NUAK1 increases the glycolytic capacity of cancer cells under mitochondrial inhibition. Nuclear NUAK1 seems to be involved in the metabolic switch to glycolysis. Altogether, our results suggest that cytosolic NUAK1 participates in mitochondrial ATP production and the maintenance of proper glycolysis in cancer cells. Our current studies support the role of NUAK1 in bioenergetics, mitochondrial homeostasis, glycolysis and metabolic capacities. They suggest different metabolic outcomes depending on its subcellular localization. The identified roles of NUAK1 in cancer metabolism provide a potential mechanism relevant for tumor progression and its association with poor patient prognosis in several cancers. Further studies could shed light on the molecular mechanisms involved in the identified metabolic NUAK1 functions.

Gene Expression Classification of Lung Adenocarcinoma into Molecular Subtypes

As one of the most common malignancies in the world, lung adenocarcinoma (LUAD) is currently difficult to cure. However, the advent of precision medicine provides an opportunity to improve the treatment of lung cancer. Subtyping lung cancer plays an important role in performing a specific treatment. Here, we developed a framework that combines k-means clustering, t-test, sensitivity analysis, self-organizing map (SOM) neural network, and hierarchical clustering methods to classify LUAD into four subtypes. We determined that 24 differentially expressed genes could be used as therapeutic targets, and five genes (i.e., RTKN2, ADAM6, SPINK1, COL3A1, and COL1A2) could be potential novel markers for LUAD. Multivariate analysis showed that the four subtypes could serve as prognostic subtypes. Representative genes of each subtype were also identified, which could be potentially targetable markers for the different subtypes. The function and pathway enrichment analyses of these representative genes showed that the four subtypes have different pathological mechanisms. Mutations associated with the subtypes, e.g., epidermal growth factor receptor (EGFR) mutations in subtype 4 and tumor protein p53 (TP53) mutations in subtypes 1 and 2, could serve as potential markers for drug development. The four subtypes provide a foundation for subtype-specific therapy of LUAD.

Good Cop, Bad Cop: Defining the Roles of Δ40p53 in Cancer and Aging

The tumour suppressor p53 is essential for maintaining DNA integrity, and plays a major role in cellular senescence and aging. Understanding the mechanisms that contribute to p53 dysfunction can uncover novel possibilities for improving cancer therapies and diagnosis, as well as cognitive decline associated with aging. In recent years, the complexity of p53 signalling has become increasingly apparent owing to the discovery of the p53 isoforms. These isoforms play important roles in regulating cell growth and turnover in response to different stressors, depending on the cellular context. In this review, we focus on Δ40p53, an N-terminally truncated p53 isoform. Δ40p53 can alter p53 target gene expression in both a positive and negative manner, modulating the biological outcome of p53 activation; it also functions independently of p53. Therefore, proper control of the Δ40p53: p53 ratio is essential for normal cell growth, aging, and responses to cancer therapy. Defining the contexts and the mechanisms by which Δ40p53 behaves as a "good cop or bad cop" is critical if we are to target this isoform therapeutically.

Regulating tumor suppressor genes: post-translational modifications

Tumor suppressor genes cooperate with each other in tumors. Three important tumor suppressor proteins, retinoblastoma (Rb), p53, phosphatase, and tensin homolog deleted on chromosome ten (PTEN) are functionally associated and they regulated by post-translational modification (PTMs) as well. PTMs include phosphorylation, SUMOylation, acetylation, and other novel modifications becoming growing appreciated. Because most of PTMs are reversible, normal cells use them as a switch to control the state of cells being the resting or proliferating, and PTMs also involve in cell survival and cell cycle, which may lead to abnormal proliferation and tumorigenesis. Although a lot of studies focus on the importance of each kind of PTM, further discoveries shows that tumor suppressor genes (TSGs) form a complex "network" by the interaction of modification. Recently, there are several promising strategies for TSGs for they change more frequently than carcinogenic genes in cancers. We here review the necessity, characteristics, and mechanisms of each kind of post-translational modification on Rb, p53, PTEN, and its influence on the precise and selective function. We also discuss the current antitumoral therapies of Rb, p53 and PTEN as predictive, prognostic, and therapeutic target in cancer.

Association of TP53 Codon 72 Arg>Pro Polymorphism with Breast and Lung Cancer Risk in the South Asian Population: A Meta-Analysis

BACKGROUND

A transversion missense polymorphism of the TP53 tumor suppressor gene at the codon 72 codes proline instead of arginine causes an altered p53 protein expression and has been found to be associated with an elevated risk of various cancer; especially breast and lung cancer. As the previous case-control studies on the South Asian population have shown controversial results, we performed a meta-analysis to evaluate a precise estimation of the relationship between the TP53 Arg72Pro polymorphism with breast and lung cancer.

METHODS

A total of 12 related studies on the South Asian population have been included through comprehensive database searching. Six studies were selected for breast cancer meta-analysis involving 950 cases and 882 controls; the other six studies were for lung cancer meta-analysis including 975 cases and 1397 controls. The results have been determined by using the Review Manager (RevMan) 5.3. Additionally, the stability of our analysis was assessed by heterogeneity, publication bias analysis and sensitivity testing.

RESULTS

A significantly increased risk of breast cancer was found in Pro allele (Pro vs. Arg), co-dominant model 2 (Pro/Pro vs. Arg/Arg), dominant model (Pro/Pro + Arg/Pro vs. Arg/Arg). In case of lung cancer, significantly increased risk was found in the allele, co-dominant 1, co-dominant 2, co-dominant 3, dominant, and recessive models. No association with other genetic models with breast and lung cancer risk was found in the South Asian population.

CONCLUSIONS

Our results indicate that TP53 Arg72Pro polymorphism is a risk factor for the development of breast cancer and lung cancer in the South Asian population.

Harnessing big 'omics' data and AI for drug discovery in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary adult liver cancer. After nearly a decade with sorafenib as the only approved treatment, multiple new agents have demonstrated efficacy in clinical trials, including the targeted therapies regorafenib, lenvatinib and cabozantinib, the anti-angiogenic antibody ramucirumab, and the immune checkpoint inhibitors nivolumab and pembrolizumab. Although these agents offer new promise to patients with HCC, the optimal choice and sequence of therapies remains unknown and without established biomarkers, and many patients do not respond to treatment. The advances and the decreasing costs of molecular measurement technologies enable profiling of HCC molecular features (such as genome, transcriptome, proteome and metabolome) at different levels, including bulk tissues, animal models and single cells. The release of such data sets to the public enhances the ability to search for information from these legacy studies and provides the opportunity to leverage them to understand HCC mechanisms, rationally develop new therapeutics and identify candidate biomarkers of treatment response. Here, we provide a comprehensive review of public data sets related to HCC and discuss how emerging artificial intelligence methods can be applied to identify new targets and drugs as well as to guide therapeutic choices for improved HCC treatment.

The Role of p53-Mediated Signaling in the Therapeutic Response of Colorectal Cancer to 9F, a Spermine-Modified Naphthalene Diimide Derivative

Colorectal cancer (CRC) is one of the most prevalent cancers due to its frequency and high rate of mortality. Polyamine-vectorized anticancer drugs possess multiple biological properties. Of these drugs, 9F has been shown to inhibit tumor growth and the metastasis of hepatocellular carcinoma. This current study aims to investigate the effects of 9F on CRC and determine its molecular mechanisms of action. Our findings demonstrate that 9F inhibits CRC cell growth by inducing apoptosis and cell cycle arrest, and suppresses migration, invasion and angiogenesis in vitro, resulting in the inhibition of tumor growth and metastasis in vivo. Based on RNA-seq data, further bioinformatic analyses suggest that 9F exerts its anticancer activities through p53 signaling, which is responsible for the altered expression of key regulators of the cell cycle, apoptosis, the epithelial-to-mesenchymal transition (EMT), and angiogenesis. In addition, 9F is more effective than amonafide against CRC. These results show that 9F can be considered as a potential strategy for CRC treatment.

p53 CRISPR Deletion Affects DNA Structure and Nuclear Architecture

The TP53 gene is a key tumor suppressor. Although the tumor suppressor p53 was one of the first to be characterized as a transcription factor, with its main function potentiated by its interaction with DNA, there are still many unresolved questions about its mechanism of action. Here, we demonstrate a novel role for p53 in the maintenance of nuclear architecture of cells. Using three-dimensional (3D) imaging and spectral karyotyping, as well as super resolution microscopy of DNA structure, we observe significant differences in 3D telomere signatures, DNA structure and DNA-poor spaces as well gains or losses of chromosomes, between normal and tumor cells with CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-deleted or wild-type TP53. Additionally, treatment with Nutlin-3 results in differences in nuclear architecture of telomeres in wild-type but not in p53 knockout MCF-7 (Michigan Cancer Foundation-7) cells. Nutlin-3 binds to the p53-binding pocket of mouse double minute 2 (MDM2) and blocks the p53-MDM2 interaction. Moreover, we demonstrate that another p53 stabilizing small molecule, RITA (reactivation of p53 and induction of tumor cell apoptosis), also induces changes in 3D DNA structure, apparently in a p53 independent manner. These results implicate p53 activity in regulating nuclear organization and, additionally, highlight the divergent effects of the p53 targeting compounds Nutlin-3 and RITA.

Identification of key genes associated with multiple sclerosis based on gene expression data from peripheral blood mononuclear cells

The aim of this study was to identify the potential key candidate genes of multiple sclerosis (MS) and uncover mechanisms in MS. We combined data from the microarray expression profile of three MS stages and performed bioinformatics analysis. Differentially expressed genes (DEGs) were identified among the distinct stages of MS and healthy controls, and a total of 349 shared DEGs were identified. Gene ontology (GO) and pathway enrichment analyses showed that the DEGs were significantly enriched in the biological processes (BPs) of purine-related metabolic processes and signaling, especially the common DEGs, which were enriched in some immunological processes. Most of the DEGs were enriched in signaling pathways associated with the immune system, some immune diseases and infectious disease pathways. Through a protein-protein interaction (PPI) network analysis and a gene expression regulatory network constructed with MS-related miRNAs, we confirmed FOS, TP53, VEGFA, JUN, HIF1A, RB1, PTGS2, CXCL8, OAS2, NFKBIA and OAS1 as candidate genes of MS. Furthermore , we explored the potential SNPs associated with MS by database mining. In conclusion, this study provides the identified genes, SNPs, biological processes, and cellular pathways associated with MS. The uncovered candidate genes may be potential biomarkers involved in the diagnosis and therapy of MS.

Generation and Interpretation of Context-Specific Human Protein-Protein Interaction Networks with HIPPIE

High-throughput techniques for the detection of protein-protein interactions (PPIs) have enabled a systems approach for the study of the living cell. However, the increasing amount of protein interaction data, the varying quality of these measurements, and the lack of context information make it difficult to construct meaningful and reliable protein networks.The Human Integrated Protein-Protein Interaction rEference (HIPPIE) is a web tool that integrates and annotates experimentally supported human PPIs from a heterogeneous set of data sources. In HIPPIE, one can query for the interactors of one or more proteins and generate high-quality and context-specific networks. This chapter highlights HIPPIE's most important features and exemplifies its functionality through a proposed use case.

ATF-2 and Tpl2 regulation of endothelial cell cycle progression and apoptosis

Cells respond to soluble and membrane-bound factors to activate signalling cascades that control cell proliferation and cell death. Vascular endothelial growth factor A (VEGF-A) is a soluble ligand that modulates a variety of cellular responses including cell proliferation and apoptosis. It is not well understood how VEGF-A signalling pathways regulate cell proliferation and cell death. To address this, we examined VEGF-A-regulated signalling pathways in the cytosol and nucleus and functional requirement for such cellular responses. The VEGF-A-regulated transcription factor, ATF-2, is required for cell cycle proteins such as p53, p21 and Cyclin D1. A cytosolic serine/threonine protein kinase (Tpl2) modulates ATF-2-regulated effects on the endothelial cell cycle. Such regulatory effects impact on endothelial cell proliferation, cell viability and apoptosis. These cellular effects influence complex cell-based organisation such as endothelial tubulogenesis. Our study now provides a framework for incorporating VEGF-A-stimulated signalling events from the cytosol to the nucleus which helps to understand how cell proliferation and apoptosis are controlled.

The Rich World of p53 DNA Binding Targets: The Role of DNA Structure

The tumor suppressor functions of p53 and its roles in regulating the cell cycle, apoptosis, senescence, and metabolism are accomplished mainly by its interactions with DNA. p53 works as a transcription factor for a significant number of genes. Most p53 target genes contain so-called p53 response elements in their promoters, consisting of 20 bp long canonical consensus sequences. Compared to other transcription factors, which usually bind to one concrete and clearly defined DNA target, the p53 consensus sequence is not strict, but contains two repeats of a 5′RRRCWWGYYY3′ sequence; therefore it varies remarkably among target genes. Moreover, p53 binds also to DNA fragments that at least partially and often completely lack this consensus sequence. p53 also binds with high affinity to a variety of non-B DNA structures including Holliday junctions, cruciform structures, quadruplex DNA, triplex DNA, DNA loops, bulged DNA, and hemicatenane DNA. In this review, we summarize information of the interactions of p53 with various DNA targets and discuss the functional consequences of the rich world of p53 DNA binding targets for its complex regulatory functions.

Rapid generation and selection of Cas9-engineering TRP53 R172P mice that do not have off-target effects

BACKGROUND

Genetic mutations cause severe human diseases, and suitable animal models to study the regulatory mechanisms involved are required. The CRISPR/Cas9 system is a powerful, highly efficient and easily manipulated tool for genetic modifications. However, utilization of CRISPR/Cas9 to introduce point mutations and the exclusion of off-target effects in mice remain challenging. TP53-R175 is one of the most frequently mutated sites in human cancers, and it plays crucial roles in human diseases, including cancers and diabetes.

RESULTS

Here, we generated TRP53-R172P mutant mice (C57BL/6 J, corresponding to TP53-R175P in humans) using a single microinjection of the CRISPR/Cas9 system. The optimal parameters comprised gRNA selection, donor designation (silent mutations within gRNA region), the concentration of CRISPR components and the cellular sites of injection. TRP53-R172P conversion was genetically and functionally confirmed. Combination of TA cloning and Sanger sequencing helped identify the correctly targeted mice as well as the off-target effects in the engineered mice, which provide us a strategy to select the on-target mice without off-target effects quickly and efficiently.

CONCLUSIONS

A single injection of the this optimized CRISPR/Cas9 system can be applied to introduce particular mutations in the genome of mice without off-target effects to model various human diseases.

DNA methylation modifier LSH inhibits p53 ubiquitination and transactivates p53 to promote lipid metabolism

BACKGROUND

The stability of p53 is mainly controlled by ubiquitin-dependent degradation, which is triggered by the E3 ubiquitin ligase MDM2. The chromatin modifier lymphoid-specific helicase (LSH) is essential for DNA methylation and cancer progression as a transcriptional repressor. The potential interplay between chromatin modifiers and transcription factors remains largely unknown.

RESULTS

Here, we present data suggesting that LSH regulates p53 in cis through two pathways: prevention proteasomal degradation through its deubiquitination, which is achieved by reducing the lysine 11-linked, lysine 48-linked polyubiquitin chains (K11 and K48) on p53; and revival of the transcriptional activity of p53 by forming a complex with PKM2 (pyruvate kinase 2). Furthermore, we confirmed that the LSH-PKM2 interaction occurred at the intersubunit interface region of the PKM2 C-terminal region and the coiled-coil domains (CC) and ATP-binding domains of LSH, and this interaction regulated p53-mediated transactivation in cis in lipid metabolism, especially lipid catabolism.

CONCLUSION

These findings suggest that LSH is a novel regulator of p53 through the proteasomal pathway, thereby providing an alternative mechanism of p53 involvement in lipid metabolism in cancer.

Matrix metalloproteases and TIMPs as prognostic biomarkers in breast cancer patients treated with radiotherapy: A pilot study

Breast cancer (BC) is the most common tumour in women and one of the most important causes of cancer death worldwide. Radiation therapy (RT) is widely used for BC treatment. Some proteins have been identified as prognostic factors for BC (Ki67, p53, E‐cadherin, HER2). In the last years, it has been shown that variations in the expression of MMPs and TIMPs may contribute to the development of BC. The aim of this pilot work was to study the effects of RT on different MMPs (‐1, ‐2, ‐3, ‐7, ‐8, ‐9, ‐10, ‐12 and ‐13) and TIMPs (‐1 to ‐4), as well as their relationship with other variables related to patient characteristics and tumour biology. A group of 20 BC patients treated with RT were recruited. MMP and TIMP serum levels were analysed by immunoassay before, during and after RT. Our pilot study showed a slight increase in the levels of most MMP and TIMP with RT. However, RT produced a significantly decrease in TIMP‐1 and TIMP‐3 levels. Significant correlations were found between MMP‐3 and TIMP‐4 levels, and some of the variables studied related to patient characteristics and tumour biology. Moreover, MMP‐9 and TIMP‐3 levels could be predictive of RT toxicity. For this reason, MMP‐3, MMP‐9, TIMP‐3 and TIMP‐4 could be used as potential prognostic and predictive biomarkers for BC patients treated with RT.

PAS Domain Containing Repressor 1 (PASD1) Promotes Glioma Cell Proliferation Through Inhibiting Apoptosis In Vitro

Background

PAS domain containing repressor 1 (PASD1), the cancer-testis antigen (CTA), has been reported to be aberrantly expressed in various cancer tissues and cancer cell lines; however, normal PASD1 expression can be detected in normal tissue, excluding testicular tissue. Moreover, PASD1 is reported to be abnormally expressed in various malignant tumors. However, it remains unclear whether PASD1 participates in tumorigenesis of glioma.

Material/Methods

PASD1 expression was detected by immunohistochemistry in 155 glioma tissue specimens in this study. Furthermore, the relationship of PASD1 expression with clinicopathological features in glioma cases was statistically analyzed. In addition, PASD1 was knocked down by small interference RNA (shRNA) in glioma cell line (LN229), so as to assess the potential to use it as the target for treating glioma.

Results

Our findings suggested that PASD1 expression in glioma patients was extremely upregulated compared with that in normal tissue samples and cell lines. Moreover, PASD1 expression was found to be markedly correlated with gender, The World Health Organization grade and p53 expression; in addition, high PASD1 expression indicated poor prognosis for glioma patients. Additionally, downregulation of PASD1 inhibited the proliferation ability of cells and resulted in cell arrest at the G2/M phase, which was achieved through accelerating apoptosis. Furthermore, our results indicated that PASD1 downregulation could upregulate some apoptosis-modulating proteins at the same time it downregulated some cycle-regulating proteins.

Conclusions

Taken together, our findings demonstrated that PASD1, an oncogene, can potentially serve as an independent prognostic factor for glioma patients.

Nb-induced stabilisation of p53 in HPV-infected cells

Cervical cancer is caused by a persistent infection of the mucosal epithelia with high-risk human papilloma viruses (HPVs). The viral oncoprotein E6 is responsible for the inactivation of the tumour suppressor p53 and thus plays a crucial role in HPV-induced tumorigenesis. The viral E6 protein forms a trimeric complex with the endogenous E3 ubiquitine ligase E6AP and the DNA-binding domain (DBD) of p53, which results in the polyubiquitination and proteasomal degradation of p53. We have developed nanobodies (Nbs) against the DBD of p53, which substantially stabilise p53 in HeLa cells. The observed effect is specific for HPV-infected cells, since similar effects were not seen for U2OS cells. Despite the fact that the stabilised p53 was strongly nuclear enriched, its tumour suppressive functions were hampered. We argue that the absence of a tumour suppressive effect is caused by inhibition of p53 transactivation in both HPV-infected and HPV-negative cells. The inactivation of the transcriptional activity of p53 was associated with an increased cellular proliferation and viability of HeLa cells. In conclusion, we demonstrate that p53 DBD Nbs positively affect protein stability whilst adversely affecting protein function, attesting to their ability to modulate protein properties in a very subtle manner.

Proteinase-activated receptor-2 enhances Bcl2-like protein-12 expression in lung cancer cells to suppress p53 expression

INTRODUCTION

The pathogenesis of lung cancer is unclear. Less expression of p53 or p53 mutation was identified in lung cancer cells, which plays a role in the development of lung cancer. Recent reports indicate that Bcl2-like protein-12 (Bcl2L12) can inhibit the expression of p53. Lung cancer cells express proteinase-activated receptor-2 (PAR2). This study tests the hypothesis that activation of PAR2 inhibits the expression of p53 in lung cancer cells.

MATERIAL AND METHODS

Lung cancer cells were collected from patients with non-small cell lung cancer (NSCLC). The cells were exposed to active peptides or trypsin in the culture for 48 h. The expression of p53 was assessed by RT-qPCR and Western blotting.

RESULTS

We observed that lung cancer cells express Bcl2L12. Activation of PAR2 increases expression of Bcl2L12 in lung cancer cells. Bcl2L12 mediates PAR2-suppressed p53 expression in lung cancer cells. IgE-activated mast cell suppression of p53 expression in lung cancer cells can be prevented by knocking down Bcl2L12. The Bcl2L12 bound Mdm2, the transcription factor of p53, to prevent the Mdm2 from binding to the promoter of p53 and thus inhibited p53 expression in lung cancer cells. PAR2 could attenuate lung cancer cell apoptosis via inducing Bcl2L12.

CONCLUSIONS

Lung cancer cells express Bcl2L12, which mediates the effects of activation of PAR2 on suppressing the expression of p53 in lung cancer cells, implying that Bcl2L12 may be a novel therapeutic target for the treatment of lung cancer.

TP53 mediated miR-3647-5p prevents progression of cervical carcinoma by targeting AGR2

Previous studies have shown that miRNAs involved in a number of biological processes, such as cell growth, development, differentiation, and apoptosis. The dysregulation of miRNA expression is associated with various diseases, including cervical cancer. However, the involvement of miR-3647-5p in the progression of tumors is unclear. In this study, we confirmed that miR-3647-5p was down-regulated during cervical carcinogenesis and development, which was positively correlated with the prognosis of patients with cervical cancer. In addition, our study showed that miR-3647-5p can inhibit the proliferation of cervical cancer cells and promote apoptosis, suggesting that miR-3647-5p is involved in the development of cervical cancer as a tumor suppressor gene. Furthermore, we found that transcription factor TP53 could promote the expression of miR-3647-5p, suggesting that the dysfunction of miR-3647-5p in cervical cancer may be related to TP53. In addition, we also found that miR-3647-5p can inhibit the proliferation of cervical cancer cells and promote apoptosis by targeting AGR2. In summary, our research reveals that transcription factor TP53 promotes the expression of miR-3647-5p, while up-regulated miR-3647-5p targets AGR2, inhibiting cervical cancer cell proliferation and promoting apoptosis. Our study reveals the mechanism of TP53/miR-3647-5p/AGR2 axis in cervical cancer, which may be useful for targeted therapy of cervical cancer.

iTRAQ-based proteomic and bioinformatic characterization of human mast cells upon infection by the influenza A virus strains H1N1 and H5N1

Mast cells can support the replication of influenza A virus, although how this occurs is poorly understood. In the present study, using quantitative MS, we analyzed the proteome of human mast cells infected with different influenza A virus strains at 12 h post-infection. Forty-one differentially expressed proteins were identified in human mast cells upon infection by the virulent H5N1 (A/Chicken/Henan/1/04) virus compared to the seasonal H1N1 (A/WSN/33) virus. Bioinformatic analyses confirmed that H1N1 significantly regulates the RNA degradation pathway via up-regulation of CCR4-NOT transcription complex subunit 4, whereas apoptosis could be suppressed by H5N1 via down-regulation of the tumor protein p53 signaling pathway with P ≤ 0.05 at 12 h post-infection. The hypoxia-inducible factor-1 signaling pathway of human mast cells is more susceptible to infection by H5N1 than by H1N1 virus.

The Spatiotemporal Pattern and Intensity of p53 Activation Dictates Phenotypic Diversity in p53-Driven Developmental Syndromes

Inappropriate activation of the p53 transcription factor contributes to numerous developmental syndromes characterized by distinct constellations of phenotypes. How p53 drives exquisitely specific sets of symptoms in diverse syndromes, however, remains enigmatic. Here, we deconvolute the basis of p53-driven developmental syndromes by leveraging an array of mouse strains to modulate the spatial expression pattern, temporal profile, and magnitude of p53 activation during embryogenesis. We demonstrate that inappropriate p53 activation in the neural crest, facial ectoderm, anterior heart field, and endothelium induces distinct spectra of phenotypes. Moreover, altering the timing and degree of p53 hyperactivation substantially affects the phenotypic outcomes. Phenotypes are associated with p53-driven cell-cycle arrest or apoptosis, depending on the cell type, with gene expression programs, rather than extent of mitochondrial priming, largely governing the specific response. Together, our findings provide a critical framework for decoding the role of p53 as a mediator of diverse developmental syndromes.

p53 modifications: exquisite decorations of the powerful guardian

The last 40 years have witnessed how p53 rose from a viral binding protein to a central factor in both stress responses and tumor suppression. The exquisite regulation of p53 functions is of vital importance for cell fate decisions. Among the multiple layers of mechanisms controlling p53 function, posttranslational modifications (PTMs) represent an efficient and precise way. Major p53 PTMs include phosphorylation, ubiquitination, acetylation, and methylation. Meanwhile, other PTMs like sumoylation, neddylation, O-GlcNAcylation, adenosine diphosphate (ADP)-ribosylation, hydroxylation, and β-hydroxybutyrylation are also shown to play various roles in p53 regulation. By independent action or interaction, PTMs affect p53 stability, conformation, localization, and binding partners. Deregulation of the PTM-related pathway is among the major causes of p53-associated developmental disorders or diseases, especially in cancers. This review focuses on the roles of different p53 modification types and shows how these modifications are orchestrated to produce various outcomes by modulating p53 activities or targeted to treat different diseases caused by p53 dysregulation.

Role of Survivin and p53 Expression in Response of Primary Culture of Ovarian Cancer Cells to Treatment With Chemotherapeutic Agents

BACKGROUND

Ovarian cancer is associated with a high relapse rate and is the fifth leading cause of cancer deaths in women. The genetic profile of a tumor is responsible for deciding response to chemotherapeutic agents. In this study, we investigate the relation between survivin and p53 expression and response to chemotherapeutic agents of primary cultures of ovarian cancer cells established from ascitic fluid.

MATERIALS AND METHOD

Ascitic fluid and Dulbecco's modified Eagle medium was mixed in equal proportion in culture flasks and incubated to establish primary culture. The cells were treated with different combinations of carboplatin and paclitaxel with and without survivin small interfering RNA transfection. Cell survival was estimated by MTT assay. Survivin and p53 expression was quantified by real-time polymerase chain reaction.

RESULTS

Out of 19 ascitic fluid samples, 13 primary cultures of ovarian cancer cells were established. The half maximal inhibitory concentration doses of carboplatin (≥70 μg/mL) and paclitaxel (≥18 μg/mL) were high for 10/13 and 5/13 patients, respectively. Survivin messenger RNA expression was significantly downregulated on treatment with carboplatin (100 μg/mL), paclitaxel (12.5 μg/mL), and a combination of carboplatin (50 μg/mL) and paclitaxel (6.25 μg/mL). Only paclitaxel-treated ovarian cancer cells showed decrease in expression of p53. Survivin small interfering RNA increased sensitivity of the primary cultures to chemotherapeutic agents.

CONCLUSIONS

The present study highlights the fact that establishing primary cultures from ascitic fluid may help to develop personalized treatment regime for individual patients based on their molecular profile. Our study also shows that supplementing taxols drugs with survivin inhibitors may prove to be beneficial in the treatment of ovarian cancer patients.

Man-made mineral fiber effects on the expression of anti-oncogenes P53 and P16 and oncogenes C-JUN and C-FOS in the lung tissue of Wistar rats

Man-made mineral fibers (MMMFs) are substitutes for asbestos. MMMFs are widely used as insulation, but their molecular mechanisms underlying the tumorigenic effects in vivo have been poorly studied. For this reason, this work aimed to explore the properties and carcinogenic molecular mechanisms of MMMFs. The three MMMFs, rock wool (RW), glass fibers (GFs), and ceramic fibers (CFs), were prepared into respirable dust. Particle size, morphology, and chemical composition were analyzed by laser particle analyzer, scanning electron microscope, and X-ray fluorescence spectrometer, respectively. The Wistar rats were administered multiple intratracheal instillations of three MMMFs once a month. Then, several parameters (e.g. body mass, lung mass, and lung histology) were measured at 1, 3, and 6 months. After that, levels of P53, P16, C-JUN, and C-FOS mRNA and protein were measured by quantitative real-time reverse transcription polymerase chain reaction and Western blotting. This work found that exposure to MMMFs could influence the growth of body mass and increase lung mass. General conditions showed white nodules and irregular atrophy. In addition, MMMFs could lead to inactivation of anti-oncogene P16 and activation of proto-oncogenes (C-JUN and C-FOS) in the mRNA and protein levels, in which GF and CF were more obvious compared with RW. The effect of MMMFs was different, which may be related to the physical and chemical characteristics of different MMMFs. In conclusion, MMMFs (GF and CF) could induce an unbalanced expression of cancer-related genes in the lung tissues of rats. The understanding of the determinants of toxicity and carcinogenicity provides a scientific basis for developing and introducing new safer MMMF products, and the present study provides some useful insights into the carcinogenic mechanism of MMMFs.

Autophagy as a molecular target for cancer treatment

Autophagy is an evolutionarily conserved catabolic mechanism, by which eukaryotic cells recycle or degrades internal constituents through membrane-trafficking pathway. Thus, autophagy provides the cells with a sustainable source of biomolecules and energy for the maintenance of homeostasis under stressful conditions such as tumor microenvironment. Recent findings revealed a close relationship between autophagy and malignant transformation. However, due to the complex dual role of autophagy in tumor survival or cell death, efforts to develop efficient treatment strategies targeting the autophagy/cancer relation have largely been unsuccessful. Here we review the two-faced role of autophagy in cancer as a tumor suppressor or as a pro-oncogenic mechanism. In this sense, we also review the shared regulatory pathways that play a role in autophagy and malignant transformation. Finally, anti-cancer therapeutic agents used as either inhibitors or inducers of autophagy have been discussed.

Silencing UBE4B induces nasopharyngeal carcinoma apoptosis through the activation of caspase3 and p53

Aim

The human ubiquitination factor E4B (UBE4B) gene is frequently amplified in some solid cancers. However, the role of UBE4B in nasopharyngeal carcinoma (NPC) has not yet been investigated.

Methods

Firstly, we analyzed the expression of UBE4B in NPC samples using real-time quantitative PCR and Western blot analysis. After knocking down UBE4B using small interfering RNA technology, the functions of UBE4B on cell proliferation, apoptosis, and cell cycle, as well as underlying mechanism, were investigated.

Results

Compared with matched adjacent non-tumor tissues, both protein and mRNA levels of UBE4B were much higher in most NPC cancerous specimens. Deficiency of UBE4B could significantly inhibit tumor cell growth and induce cell apoptosis. Knocking down UBE4B could promote the expression of cleaved caspase3 and p53, and inhibition of caspase3 could prevent cell apoptosis induced by the deficiency of UBE4B.

Conclusion

These results indicate that expression of UBE4B was higher in most NPC tissues compared to adjacent non-tumoral tissues, and that knockdown of UBE4B inhibited the cell growth and induced apoptosis in NPC cells. This process was regulated by the activation of caspase3 and p53. Thus, UBE4B gene might act as a potential molecular target to develop novel strategy for NPC patients.

Quality and bias of protein disorder predictors

Disorder in proteins is vital for biological function, yet it is challenging to characterize. Therefore, methods for predicting protein disorder from sequence are fundamental. Currently, predictors are trained and evaluated using data from X-ray structures or from various biochemical or spectroscopic data. However, the prediction accuracy of disordered predictors is not calibrated, nor is it established whether predictors are intrinsically biased towards one of the extremes of the order-disorder axis. We therefore generated and validated a comprehensive experimental benchmarking set of site-specific and continuous disorder, using deposited NMR chemical shift data. This novel experimental data collection is fully appropriate and represents the full spectrum of disorder. We subsequently analyzed the performance of 26 widely-used disorder prediction methods and found that these vary noticeably. At the same time, a distinct bias for over-predicting order was identified for some algorithms. Our analysis has important implications for the validity and the interpretation of protein disorder, as utilized, for example, in assessing the content of disorder in proteomes.

Calpain-mediated cleavage of p53 in human cytomegalovirus-infected lung fibroblasts

Endogenous fragments of p53 protein were identified in human cytomegalovirus (HCMV)-infected human lung fibroblasts, particularly a 44-kDa N-terminal fragment [hereafter referred to as p53(ΔCp44)], generated via calpain cleavage. The fragment abundance increased in a biphasic manner, peaking at 6-9 hours and 48 hours post infection. Treatment of LU cells with calpain inhibitors eliminated most detectable p53 fragments. In cell-free experiments, exogenous m-calpain cleavage generated p53(ΔCp44). Attempts to preserve p53 proteins by treating cells with the calpain inhibitor E64d for 6 hours before harvesting increased the sensitivity of p53 to calpain cleavage. p53 in mock-infected cell lysates was much more sensitive to cleavage and degradation by exogenous calpain than that in HCMV-infected cells. The proteasome inhibitor MG132 stabilized p53(ΔCp44), particularly in mock-infected cells. p53(ΔCp44) appeared to be tightly associated with a chromatin-rich fraction. The abundance of p53β was unchanged over a 96-h time course and very similar in mock- and HCMV-infected cells, making it unlikely that p53(ΔCp44) was p53β. The biological activities of this and other fragments lacking C-terminal sequences are unknown, but deserve further investigation, given the association of p53(ΔCp44) with the chromatin-rich (or buffer C insoluble) fraction in HCMV-infected cells.

Wild-Type p53 Promotes Cancer Metabolic Switch by Inducing PUMA-Dependent Suppression of Oxidative Phosphorylation

The tumor suppressor p53 is somatically mutated in half of all human cancers. Paradoxically, the wild-type p53 (WTp53) is often retained in certain human cancers, such as hepatocarcinoma (HCC). We discovered a physiological and oncogenic role of WTp53 in suppressing pyruvate-driven oxidative phosphorylation by inducing PUMA. PUMA inhibits mitochondrial pyruvate uptake by disrupting the oligomerization and function of mitochondrial pyruvate carrier (MPC) through PUMA-MPC interaction, which depends on IκB kinase-mediated phosphorylation of PUMA at Ser96/106. High expression levels of PUMA are correlated with decreased mitochondrial pyruvate uptake and increased glycolysis in HCCs and poor prognosis of HCC patients. These findings are instrumental for cancer drug discovery aiming at activating WTp53 or restoring WTp53 activity to p53 mutants.