The ARF/p53 pathway

Exploring natural products as apoptosis modulators in cancers: insights into natural product-based therapeutic strategies

Cancer remains a leading cause of mortality globally, necessitating ongoing research and development of innovative therapeutic strategies. Natural products from plants, herbs, and marine species have shown great promise as anti-cancer therapies due to their bioactive components that alter cellular pathways, particularly apoptosis. This review explores the mechanism by which natural chemicals trigger the apoptosis of cancerous cells, which is crucial for eliminating them and halting tumor growth. These can affect the mitochondrial process by controlling the Bcl-2 protein family, increasing cytochrome c release, and activating caspases. They also activate death receptors like Fas and TRAIL to enhance the extrinsic apoptotic pathway. We focus on the main signaling channels involved, such as the endoplasmic reticulum (ER) stress-mediated apoptosis, extrinsic death receptor, and intrinsic mitochondrial pathways. The review explores the role of natural substances such as polyphenols, terpenoids, alkaloids, and flavonoids in promoting apoptotic cell death and increasing cancer cell susceptibility, potentially aiding in cancer treatments and the potential of combining natural products with traditional chemotherapeutic medicines to combat medication resistance and enhance therapeutic efficacy. Understanding cancer development involves inhibiting cell proliferation, regulating it, targeting apoptosis pathways, and using plant and marine extracts as apoptotic inducers.

Radiotherapy Plus the Neurokinin-1 Receptor Antagonist Aprepitant: A Potent Therapeutic Strategy for the Treatment of Diffuse Intrinsic Pontine Glioma

Background: Diffuse intrinsic pontine glioma (DIPG) is a devastating childhood brainstem tumor. The median survival of DIPG is 16-24 months independent of the treatment received. Therefore, new therapeutic strategies against DIPG are urgently needed. Substance P (SP) peptide, through the neurokinin neurokinin-1 receptor (NK-1R), is involved in glioma progression. It induces glioma cell proliferation by activating MAPKs (p38 MAPK, ERK1/2, and JNK), c-Myc, AP-1, and NF-κB and induces antiapoptotic effects via PI3K/Akt/mTOR in glioma cells. SP favors glycogen breakdown that is essential for glycolysis. The SP/NK-1R system also regulates the migration and invasion of glioma cells, stimulates angiogenesis, and triggers inflammation which contributes to glioma progression. Moreover, all glioma cells express NK-1R, and NK-1R is essential for the viability of glioma cells and not of normal cells. In contrast, in glioma, NK-1R antagonists, such as the drug aprepitant, penetrate the brain and reach therapeutic concentrations, thereby inhibiting mitogenesis, inducing apoptosis, and inhibiting the breakdown of glycogen in glioma cells. In addition, they inhibit angiogenesis and exert antimetastatic and anti-inflammatory effects. The combination of radiotherapy with NK-1R antagonists produces radiosensitization and radioneuroprotection, reduces both peritumoral- and radiation-induced inflammation, and also provides antinausea and antivomiting effects. Objective: This review updates the involvement of the SP/NK-1R system in glioma promotion and progression and the potential clinical application of NK-1R antagonist drugs in DIPG therapy. Conclusions: NK-1R plays a crucial role in glioma progression and NK-1R antagonists such as aprepitant could be used in combination with radiotherapy as a potent therapeutic strategy for the treatment of patients with DIPG.

LM-Merger: A workflow for merging logical models with an application to gene regulation

Motivation

Gene regulatory network (GRN) models provide mechanistic understanding of genetic interactions that regulate gene expression and, consequently, influence cellular behavior. Dysregulated gene expression plays a critical role in disease progression and treatment response, making GRN models a promising tool for precision medicine. While researchers have built many models to describe specific subsets of gene interactions, more comprehensive models that cover a broader range of genes are challenging to build. This necessitates the development of automated approaches for merging existing models.

Results

We present LM-Merger, a workflow for semi-automatically merging logical GRN models. The workflow consists of five main steps: (a) model identification, (b) model standardization and annotation, (c) model verification, (d) model merging, and (d) model evaluation. We demonstrate the feasibility and benefit of this workflow with two pairs of published models pertaining to acute myeloid leukemia (AML). The integrated models were able to retain the predictive accuracy of the original models, while expanding coverage of the biological system. Notably, when applied to a new dataset, the integrated models outperformed the individual models in predicting patient response. This study highlights the potential of logical model merging to advance systems biology research and our understanding of complex diseases.

Availability and implementation

The workflow and accompanying tools, including modules for model standardization, automated logical model merging, and evaluation, are available at https://github.com/IlyaLab/LogicModelMerger/.

Cellular senescence and its pathogenic and therapeutic implications in autoimmune hepatitis

INTRODUCTION

Senescent cells are characterized by replicative arrest and phenotypes that produce diverse pro-inflammatory and pro-oxidant mediators. The senescence of diverse hepatic cell types could constitute an unrecognized pathogenic mechanism and prognostic determinant in autoimmune hepatitis. The impact of cellular senescence in autoimmune hepatitis is unknown, and it may suggest adjunctive management strategies.

AREAS COVERED

This review describes the molecular mechanisms of cellular senescence, indicates its diagnostic features, suggests its consequences, presents possible therapeutic interventions, and encourages investigations of its pathogenic role and management in autoimmune hepatitis. Treatment prospects include elimination or reversal of senescent cells, generation of ectopic telomerase, reactivation of dormant telomerase, neutralization of specific pro-inflammatory secretory products, and mitigation of the effects of mitochondrial dysfunction.

EXPERT OPINION

The occurrence, nature, and consequences of cellular senescence in autoimmune hepatitis must be determined. The senescence of diverse hepatic cell types could affect the outcome of autoimmune hepatitis by impairing hepatic regeneration, intensifying liver inflammation, and worsening hepatic fibrosis. Cellular senescence could contribute to suboptimal responses during conventional glucocorticoid-based therapy. Interventions that target specific pro-inflammatory products of the senescent phenotype or selectively promote apoptosis of senescent cells may be preferred adjunctive treatments for autoimmune hepatitis depending on the cancer risk.

The nucleolus: Coordinating stress response and genomic stability

The perception that the nucleoli are merely the organelles where ribosome biogenesis occurs is challenged. Only around 30 % of nucleolar proteins are solely involved in producing ribosomes. Instead, the nucleolus plays a critical role in controlling protein trafficking during stress and, according to its dynamic nature, undergoes continuous protein exchange with nucleoplasm under various cellular stressors. Hence, the concept of nucleolar stress has evolved as cellular insults that disrupt the structure and function of the nucleolus. Considering the emerging role of this organelle in DNA repair and the fact that rDNAs are the most fragile genomic loci, therapies targeting the nucleoli are increasingly being developed. Besides, drugs that target ribosome synthesis and induce nucleolar stress can be used in cancer therapy. In contrast, agents that regulate nucleolar activity may be a potential treatment for neurodegeneration caused by abnormal protein accumulation in the nucleolus. Here, I explore the roles of nucleoli beyond their ribosomal functions, highlighting the factors triggering nucleolar stress and their impact on genomic stability.

Pharmacological reactivation of p53 in the era of precision anticancer medicine

p53, which is encoded by the most frequently mutated gene in cancer, TP53, is an attractive target for novel cancer therapies. Despite major challenges associated with this approach, several compounds that either augment the activity of wild-type p53 or restore all, or some, of the wild-type functions to p53 mutants are currently being explored. In wild-type TP53 cancer cells, p53 function is often abrogated by overexpression of the negative regulator MDM2, and agents that disrupt p53-MDM2 binding can trigger a robust p53 response, albeit potentially with induction of p53 activity in non-malignant cells. In TP53-mutant cancer cells, compounds that promote the refolding of missense mutant p53 or the translational readthrough of nonsense mutant TP53 might elicit potent cell death. Some of these compounds have been, or are being, tested in clinical trials involving patients with various types of cancer. Nonetheless, no p53-targeting drug has so far been approved for clinical use. Advances in our understanding of p53 biology provide some clues as to the underlying reasons for the variable clinical activity of p53-restoring therapies seen thus far. In this Review, we discuss the intricate interactions between p53 and its cellular and microenvironmental contexts and factors that can influence p53's activity. We also propose several strategies for improving the clinical efficacy of these agents through the complex perspective of p53 functionality.

Ribosome profiling: a powerful tool in oncological research

Neoplastic cells need to adapt their gene expression pattern to survive in an ever-changing or unfavorable tumor microenvironment. Protein synthesis (or mRNA translation), an essential part of gene expression, is dysregulated in cancer. The emergence of distinct translatomic technologies has revolutionized oncological studies to elucidate translational regulatory mechanisms. Ribosome profiling can provide adequate information on diverse aspects of translation by aiding in quantitatively analyzing the intensity of translating ribosome-protected fragments. Here, we review the primary currently used translatomics techniques and highlight their advantages and disadvantages as tools for translatomics studies. Subsequently, we clarified the areas in which ribosome profiling could be applied to better understand translational control. Finally, we summarized the latest advances in cancer studies using ribosome profiling to highlight the extensive application of this powerful and promising translatomic tool.

Lack of a p16INK4a/ARF locus in fish genome may underlie senescence resistance in the fish cell line, EPC

Unlike most mammalian cell lines, fish cell lines are immortal and resistant to cellular senescence. Elevated expression of H-Ras contributes to the induction of senescence in a fish cell line, EPC, but is not sufficient to induce full senescence. Here, we focused on the absence of a p16^INK4a/ARF locus in the fish genome, and investigated whether this might be a critical determinant of the resistance of EPC cells to full senescence. We found that transfected EPC cells constitutively overexpressing p16^INK4a exhibited large size and flat morphology characteristic of prematurely senescent cells; the cells also showed p53-independent senescence-like growth arrest and senescence-associated β-galactosidase (SA-β-gal) activity. Furthermore, the mRNA levels of proinflammatory senescence-associated secretory phenotype (SASP) factors increased in EPC cells constitutively overexpressing p16^INK4a. These results suggest that the lack of p16^INK4a in the fish genome may be a critical determinant of senescence resistance in fish cell lines.

Emerging Evidence of the Significance of Thioredoxin-1 in Hematopoietic Stem Cell Aging

The United States is undergoing a demographic shift towards an older population with profound economic, social, and healthcare implications. The number of Americans aged 65 and older will reach 80 million by 2040. The shift will be even more dramatic in the extremes of age, with a projected 400% increase in the population over 85 years old in the next two decades. Understanding the molecular and cellular mechanisms of ageing is crucial to reduce ageing-associated disease and to improve the quality of life for the elderly. In this review, we summarized the changes associated with the ageing of hematopoietic stem cells (HSCs) and what is known about some of the key underlying cellular and molecular pathways. We focus here on the effects of reactive oxygen species and the thioredoxin redox homeostasis system on ageing biology in HSCs and the HSC microenvironment. We present additional data from our lab demonstrating the key role of thioredoxin-1 in regulating HSC ageing.

p53 at the crossroad of DNA replication and ribosome biogenesis stress pathways

Despite several decades of intense research focused on understanding function(s) and disease-associated malfunction of p53, there is no sign of any “mid-life crisis” in this rapidly advancing area of biomedicine. Firmly established as the hub of cellular stress responses and tumor suppressor targeted in most malignancies, p53’s many talents continue to surprise us, providing not only fresh insights into cell and organismal biology, but also new avenues to cancer treatment. Among the most fruitful lines of p53 research in recent years have been the discoveries revealing the multifaceted roles of p53-centered pathways in the fundamental processes of DNA replication and ribosome biogenesis (RiBi), along with cellular responses to replication and RiBi stresses, two intertwined areas of cell (patho)physiology that we discuss in this review. Here, we first provide concise introductory notes on the canonical roles of p53, the key interacting proteins, downstream targets and post-translational modifications involved in p53 regulation. We then highlight the emerging involvement of p53 as a key component of the DNA replication Fork Speed Regulatory Network and the mechanistic links of p53 with cellular checkpoint responses to replication stress (RS), the driving force of cancer-associated genomic instability. Next, the tantalizing, yet still rather foggy functional crosstalk between replication and RiBi (nucleolar) stresses is considered, followed by the more defined involvement of p53-mediated monitoring of the multistep process of RiBi, including the latest updates on the RPL5/RPL11/5 S rRNA-MDM2-p53-mediated Impaired Ribosome Biogenesis Checkpoint (IRBC) pathway and its involvement in tumorigenesis. The diverse defects of RiBi and IRBC that predispose and/or contribute to severe human pathologies including developmental syndromes and cancer are then outlined, along with examples of promising small-molecule-based strategies to therapeutically target the RS- and particularly RiBi- stress-tolerance mechanisms to which cancer cells are addicted due to their aberrant DNA replication, repair, and proteo-synthesis demands.

Gastric cancer exosomes contribute to the field cancerization of gastric epithelial cells surrounding gastric cancer

BACKGROUND

A dynamic molecular interaction between cancer and the surrounding normal cells is mediated through exosomes. We investigated whether exosomes derived from gastric cancer cells affected the fate of the surrounding gastric epithelial cells.

METHODS

We analyzed the cell viability and immortalization of primary normal stomach epithelial cells (PNSECs) after treatment with exosomes derived from AGS gastric cancer cells and/or H. pylori CagA. Cell proliferation and apoptosis were analyzed by BrdU incorporation, flow-cytometry, and colony formation assays. We examined telomere length, expression and activity of telomerase, and expression of telomere-related genes in PNSECs treated with cancer exosomes, and in 60 gastric cancer and corresponding mucosal tissues. The differentially expressed genes and transcriptional regulation of telomere-related genes were verified using real-time qPCR and ChIP analyses, respectively.

RESULTS

Gastric cancer exosomes increased cell viability and the population-doubling levels but inhibited the cellular senescence and apoptosis of PNSECs. The internalization of cancer exosomes in PNSECs dramatically increased the number of surviving colonies and induced a multilayer growth and invasion into the scaffold. Treatment of PNSECs with cancer exosomes markedly increased the expression and activity of telomerase and the T/S ratio and regulated the expression of the telomere-associated genes, heat-shock genes, and hedgehog genes. Compared to gastric mucosae, gastric cancer showed increased hTERT expression, which was positively correlated with telomere length. Interestingly, seven (46.7%) of 15 non-cancerous gastric mucosae demonstrated strong telomerase activity.

CONCLUSION

These results suggest that gastric cancer exosomes induced the transformation and field cancerization of the surrounding non-cancerous gastric epithelial cells.

Nutrition Interventions of Herbal Compounds on Cellular Senescence

When cells undergo large-scale senescence, organ aging ensues, resulting in irreversible organ pathology and organismal aging. The study of senescence in cells provides an important avenue to understand the factors that influence aging and can be used as one of the useful tools for examining age-related human diseases. At present, many herbal compounds have shown effects on delaying cell senescence. This review summarizes the main characteristics and mechanisms of cell senescence, age-related diseases, and the recent progress on the natural products targeting cellular senescence, with the aim of providing insights to aid the clinical management of age-related diseases.

Mutation of the Conserved Threonine 8 within the Human ARF Tumour Suppressor Protein Regulates Autophagy

Background: The ARF tumour suppressor plays a well-established role as a tumour suppressor, halting cell growth by both p53-dependent and independent pathways in several cellular stress response circuits. However, data collected in recent years challenged the traditional role of this protein as a tumour suppressor. Cancer cells expressing high ARF levels showed that its expression, far from being dispensable, is required to guarantee tumour cell survival. In particular, ARF can promote autophagy, a self-digestion pathway that helps cells cope with stressful growth conditions arising during both physiological and pathological processes. Methods: We previously showed that ARF is regulated through the activation of the protein kinase C (PKC)-dependent pathway and that an ARF phospho-mimetic mutant on the threonine residue 8, ARF-T8D, sustains cell proliferation in HeLa cells. We now explored the role of ARF phosphorylation in both basal and starvation-induced autophagy by analysing autophagic flux in cells transfected with either WT and ARF phosphorylation mutants by immunoblot and immunofluorescence. Results: Here, we show that endogenous ARF expression in HeLa cells is required for starvation-induced autophagy. Further, we provide evidence that the hyper-expression of ARF-T8D appears to inhibit autophagy in both HeLa and lung cancer cells H1299. This effect is due to the cells’ inability to elicit autophagosomes formation upon T8D expression. Conclusions: Our results lead to the hypothesis that ARF phosphorylation could be a mechanism through which the protein promotes or counteracts autophagy. Several observations underline how autophagy could serve a dual role in cancer progression, either protecting healthy cells from damage or aiding cancerous cells to survive. Our results indicate that ARF phosphorylation controls protein’s ability to promote or counteract autophagy, providing evidence of the dual role played by ARF in cancer progression.

A murine mesenchymal stem cell model for initiating events in osteosarcomagenesis points to CDK4/CDK6 inhibition as a therapeutic target

Osteosarcoma is a high-grade bone-forming neoplasm, with a complex genome. Tumours frequently show chromothripsis, many deletions, translocations and copy number alterations. Alterations in the p53 or Rb pathway are the most common genetic alterations identified in osteosarcoma. Using spontaneously transformed murine mesenchymal stem cells (MSCs) which formed sarcoma after subcutaneous injection into mice, it was previously demonstrated that p53 is most often involved in the transformation towards sarcomas with complex genomics, including osteosarcoma. In the current study, not only loss of p53 but also loss of p16^Ink4a is shown to be a driver of osteosarcomagenesis: murine MSCs with deficient p15^Ink4b, p16^Ink4a, or p19^Arf transform earlier compared to wild-type murine MSCs. Furthermore, in a panel of nine spontaneously transformed murine MSCs, alterations in p15^Ink4b, p16^Ink4a, or p19^Arf were observed in eight out of nine cases. Alterations in the Rb/p16 pathway could indicate that osteosarcoma cells are vulnerable to CDK4/CDK6 inhibitor treatment. Indeed, using two-dimensional (n = 7) and three-dimensional (n = 3) cultures of human osteosarcoma cell lines, it was shown that osteosarcoma cells with defective p16^INK4A are sensitive to the CDK4/CDK6 inhibitor palbociclib after 72-hour treatment. A tissue microarray analysis of 109 primary tumour biopsies revealed a subset of patients (20-23%) with intact Rb, but defective p16 or overexpression of CDK4 and/or CDK6. These patients might benefit from CDK4/CDK6 inhibition, therefore our results are promising and might be translated to the clinic.

Natural products inducing nucleolar stress: implications in cancer therapy

The nucleolus is the site of ribosome biogenesis and is found to play an important role in stress sensing. For over 100 years, the increase in the size and number of nucleoli has been considered as a marker of aggressive tumors. Despite this, the contribution of the nucleolus and the biologic processes mediated by it to cancer pathogenesis has been largely overlooked. This state has been changed over the recent decades with the demonstration that the nucleolus controls numerous cellular functions associated with cancer development. Induction of nucleolar stress has recently been regarded as being superior to conventional cytotoxic/cytostatic strategy in that it is more selective to neoplastic cells while sparing normal cells. Natural products represent an excellent source of bioactive molecules and some of them have been found to be able to induce nucleolar stress. The demonstration of these nucleolar stress-inducing natural products has paved the way for a new therapeutic approach to more delicate tumor cell-killing. This review provides a contemporary summary of the role of the nucleolus as a novel promising target for cancer therapy, with particular emphasis on natural products as an exciting new class of anti-cancer drugs with nucleolar stress-inducing properties.

EPDR1, Which Is Negatively Regulated by miR-429, Suppresses Epithelial Ovarian Cancer Progression via PI3K/AKT Signaling Pathway

Epithelial ovarian cancer (EOC) is the main pathological type of ovarian cancer. In this study, we found that ependymin-related 1 (EPDR1) was remarkably downregulated in EOC tissues, and low EPDR1 expression was associated with International Federation of Gynecology and Obstetrics (FIGO) stage, metastasis, and poor prognosis. We confirmed that EPDR1 overexpression dramatically suppressed EOC cell proliferation, migration, and invasion in vitro and in vivo. Mechanistically, EPDR1 inhibited EOC tumorigenesis and progression, at least in part, through the repression of the PI3K (Phosphoinositide 3-kinase)/AKT (AKT Serine/Threonine Kinase 1) signaling pathway. Furthermore, the expression and function of EPDR1 were regulated by miR-429, as demonstrated by luciferase reporter assays and rescue experiments. In conclusion, our study validated that EPDR1, negatively regulated by miR-429, played an important role as a tumor-suppressor gene in EOC development via inhibition of the PI3K/AKT pathway. The miR-429/EPDR1 axis might provide novel therapeutic targets for individualized treatment of EOC patients in the future.

TP53 in Acute Myeloid Leukemia: Molecular Aspects and Patterns of Mutation

Mutation of the tumor suppressor gene, TP53, is associated with abysmal survival outcomes in acute myeloid leukemia (AML). Although it is the most commonly mutated gene in cancer, its occurrence is observed in only 5–10% of de novo AML, and in 30% of therapy related AML (t-AML). TP53 mutation serves as a prognostic marker of poor response to standard-of-care chemotherapy, particularly in t-AML and AML with complex cytogenetics. In light of a poor response to traditional chemotherapy and only a modest improvement in outcome with hypomethylation-based interventions, allogenic stem cell transplant is routinely recommended in these cases, albeit with a response that is often short lived. Despite being frequently mutated across the cancer spectrum, progress and enthusiasm for the development of p53 targeted therapeutic interventions is lacking and to date there is no approved drug that mitigates the effects of TP53 mutation. There is a mounting body of evidence indicating that p53 mutants differ in functionality and form from typical AML cases and subsequently display inconsistent responses to therapy at the cellular level. Understanding this pathobiological activity is imperative to the development of effective therapeutic strategies. This review aims to provide a comprehensive understanding of the effects of TP53 on the hematopoietic system, to describe its varying degree of functionality in tumor suppression, and to illustrate the need for the adoption of personalized therapeutic strategies to target distinct classes of the p53 mutation in AML management.

Molecular characterization, expression, and apoptosis regulation of siva1 in protogynous hermaphrodite fish ricefield eel (Monopterus albus)

Siva1, which induces extensive apoptosis, has been well characterized. To elucidate the molecular function of Siva1 in ricefield eel, molecular characterization and phylogenetic analysis were performed, and the mRNA expression in the ovary at different developmental stages and ovary tissues exposed to H₂O₂ and Z-VAD-FMK in vitro were also evaluated. The results indicated that ricefield eel Siva1 was highly conserved and contains three conserved motifs, despite 83 amino acid differences upstream of the initiation codon. Phylogenetic analysis demonstrated that ricefield eel Siva1 clusters together with the Siva1 protein of the other fish, with high sequence homology with that of Lates calcarifer. Quantitative real-time polymerase chain reaction analysis showed high siva1 expression levels in the ovary and low expression levels in the liver. The higher mRNA levels of siva1 were detected in the IE and IM, and the lower siva1 mRNA levels were found in the OM, IL, and TE during gonadal development. Additionally, siva1 expression levels in the ovarian tissues were significantly increased at 1 h post incubation (hpi) with H₂O₂ and then significantly decreased at 2 hpi; however, siva1 expression was upregulated significantly at 4 and 8 hpi, similar to the patterns observed with caspase3, which was used as a molecular marker of apoptosis. Moreover, the siva1 mRNAs were elevated significantly than that in control groups at 1 hpi, but the expression of siva1 was down-regulated dramatically at 2, 4, and 8 hpi, which were similar with that of caspase3 expression profiles after Z-VAD-FMK incubation. What's more, Pearson's correlation coefficients showed strongly positive relationships between siva1 and caspase3. These findings suggest that Siva1 plays an important apoptosis role in gonadal development of ricefield eel.

Dying to Survive-The p53 Paradox

The p53 tumour suppressor is best known for its canonical role as "guardian of the genome", activating cell cycle arrest and DNA repair in response to DNA damage which, if irreparable or sustained, triggers activation of cell death. However, despite an enormous amount of work identifying the breadth of the gene regulatory networks activated directly and indirectly in response to p53 activation, how p53 activation results in different cell fates in response to different stress signals in homeostasis and in response to p53 activating anti-cancer treatments remains relatively poorly understood. This is likely due to the complex interaction between cell death mechanisms in which p53 has been activated, their neighbouring stressed or unstressed cells and the local stromal and immune microenvironment in which they reside. In this review, we evaluate our understanding of the burgeoning number of cell death pathways affected by p53 activation and how these may paradoxically suppress cell death to ensure tissue integrity and organismal survival. We also discuss how these functions may be advantageous to tumours that maintain wild-type p53, the understanding of which may provide novel opportunity to enhance treatment efficacy.

Genetic Events Inhibiting Apoptosis in Diffuse Large B Cell Lymphoma

Simple Summary

Diffuse large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL). Despite the genetic heterogeneity of the disease, most patients are initially treated with a combination of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), but relapse occurs in ~50% of patients. One of the hallmarks of DLBCL is the occurrence of genetic events that inhibit apoptosis, which contributes to disease development and resistance to therapy. These events can affect the intrinsic or extrinsic apoptotic pathways, or their modulators. Understanding the factors that contribute to inhibition of apoptosis in DLBCL is crucial in order to be able to develop targeted therapies and improve outcomes, particularly in relapsed and refractory DLBCL (rrDLBCL). This review provides a description of the genetic events inhibiting apoptosis in DLBCL, their contribution to lymphomagenesis and chemoresistance, and their implication for the future of DLBCL therapy.

Abstract

Diffuse large B cell lymphoma (DLBCL) is curable with chemoimmunotherapy in ~65% of patients. One of the hallmarks of the pathogenesis and resistance to therapy in DLBCL is inhibition of apoptosis, which allows malignant cells to survive and acquire further alterations. Inhibition of apoptosis can be the result of genetic events inhibiting the intrinsic or extrinsic apoptotic pathways, as well as their modulators, such as the inhibitor of apoptosis proteins, P53, and components of the NF-kB pathway. Mechanisms of dysregulation include upregulation of anti-apoptotic proteins and downregulation of pro-apoptotic proteins via point mutations, amplifications, deletions, translocations, and influences of other proteins. Understanding the factors contributing to resistance to apoptosis in DLBCL is crucial in order to be able to develop targeted therapies that could improve outcomes by restoring apoptosis in malignant cells. This review describes the genetic events inhibiting apoptosis in DLBCL, provides a perspective of their interactions in lymphomagenesis, and discusses their implication for the future of DLBCL therapy.

FBXW7 Confers Radiation Survival by Targeting p53 for Degradation

The tumor suppressor p53 plays a critical role in integrating a wide variety of stress responses. Therefore, p53 levels are precisely regulated by multiple ubiquitin ligases. In this study, we report that FBXW7, a substrate recognition component of the SKP1-CUL1-F-box (SCF) E3 ligase, interacts with and targets p53 for polyubiquitination and proteasomal degradation after exposure to ionizing radiation or etoposide. Mechanistically, DNA damage activates ATM to phosphorylate p53 on Ser33 and Ser37, which facilitates the FBXW7 binding and subsequent p53 degradation by SCF^FBXW7. Inactivation of ATM or SCF^FBXW7 by small molecular inhibitors or genetic knockdown/knockout approaches extends the p53 protein half-life upon DNA damage in an MDM2-independent manner. Biologically, FBXW7 inactivation sensitizes cancer cells to radiation or etoposide by stabilizing p53 to induce cell-cycle arrest and apoptosis. Taken together, our study elucidates a mechanism by which FBXW7 confers cancer cell survival during radiotherapy or chemotherapy via p53 targeting.

Upregulation of 5'-terminal oligopyrimidine mRNA translation upon loss of the ARF tumor suppressor

Tumor cells require nominal increases in protein synthesis in order to maintain high proliferation rates. As such, tumor cells must acquire enhanced ribosome production. How the numerous mutations in tumor cells ultimately achieve this aberrant production is largely unknown. The gene encoding ARF is the most commonly deleted gene in human cancer. ARF plays a significant role in regulating ribosomal RNA synthesis and processing, ribosome export into the cytoplasm, and global protein synthesis. Utilizing ribosome profiling, we show that ARF is a major suppressor of 5'-terminal oligopyrimidine mRNA translation. Genes with increased translational efficiency following loss of ARF include many ribosomal proteins and translation factors. Knockout of p53 largely phenocopies ARF loss, with increased protein synthesis and expression of 5'-TOP encoded proteins. The 5'-TOP regulators eIF4G1 and LARP1 are upregulated in Arf- and p53-null cells.

LEF1 Induces DHRS2 Gene Expression in Human Acute Leukemia Jurkat T-Cells

Objective

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease resulting from the accumulation of genetic changes that affect the development of T-cells. The precise role of lymphoid enhancer-binding factor 1 (LEF1) in T-ALL has been controversial since both overexpression and inactivating LEF1 mutations have been reported to date. Here, we investigate the potential gene targets of LEF1 in the Jurkat human T-cell leukemia cell line.

Materials and Methods

We used small interfering RNA (siRNA) technology to knock down LEF1 in Jurkat cells and then compared the gene expression levels in the LEF1 knockdown cells with non-targeting siRNA-transfected and non-transfected cells by employing microarray analysis.

Results

We identified DHRS2, a tumor suppressor gene, as the most significantly downregulated gene in LEF1 knockdown cells, and we further confirmed its downregulation by real-time quantitative polymerase chain reaction (qRT-PCR) in mRNA and at protein level by western blotting.

Conclusion

Our results revealed that DHRS2 is positively regulated by LEF1 in Jurkat cells, which indicates the capability of LEF1 as a tumor suppressor and, together with previous reports, suggests that LEF1 exhibits a regulatory role in T-ALL via not only its oncogenic targets but also tumor suppressor genes.

Reactive Oxygen Species Induced p53 Activation: DNA Damage, Redox Signaling, or Both?

Significance: The p53 tumor suppressor has been dubbed the "guardian of genome" because of its various roles in the response to DNA damage such as DNA damage repair, cell cycle arrest, senescence, and apoptosis, all of which are in place to prevent mutations from being passed on down the lineage. Recent Advances: Reactive oxygen species (ROS), for instance hydrogen peroxide derived from mitochondrial respiration, have long been regarded mainly as a major source of cellular damage to DNA and other macromolecules. Critical Issues: More recently, ROS have been shown to also play important physiological roles as second messengers in so-called redox signaling. It is, therefore, not clear whether the observed activation of p53 by ROS is mediated through the DNA damage response, redox signaling, or both. In this review, we will discuss the similarities and differences between p53 activation in response to DNA damage and redox signaling in terms of upstream signaling and downstream transcriptional program activation. Future Directions: Understanding whether and how DNA damage and redox signaling-dependent p53 activation can be dissected could be useful to develop anti-cancer therapeutic p53-reactivation strategies that do not depend on the induction of DNA damage and the resulting additional mutational load.

Context is key: Understanding the regulation, functional control, and activities of the p53 tumour suppressor

The p53 tumour suppressor is considered one of the most critical genes in cancer biology. By upregulating apoptosis, cell cycle arrest, and DNA damage repair in normal cells, p53 prevents the propagation of cells with tumorigenic potential; therefore, mutations in p53 are associated with carcinogenic transformation and can be accompanied by the accumulation of a novel gain-of-function oncogenic protein, mutant p53. Although p53 is most often understood to utilize context-dependent post-translational modifications to achieve regulation of its many target genes, recent research has also sought to define other mechanisms of regulating p53 gene expression prior to translation and to understand how this alternative regulation of p53 may influence target gene expression and cellular outcome. This review attempts to summarize what is known about p53 regulation at the transcriptional, post-transcriptional, and post-translational levels while paying special attention to the ways in which context may influence p53 regulation and subsequent regulation of its target genes.

Establishment and characterization of a PCOS and a normal human granulosa cell line

Oocyte maturation is an important phase in fertility and any disorder in this process could lead to infertility. The most common disorder during folliculogenesis is polycystic ovary syndrome (PCOS). Due to the secretive activity of granulosa cells (GCs), they play a vital role in folliculogenesis. Although scientists use various cellular and molecular methods to have a better understanding of the mechanism of these cells, some limitations still exist in GC culture such as low primary cell yield and proliferation capability. Therefore, immortalization of primary cells is an approach to overcome these limitations. In the current study, GCs were obtained from two females, one with PCOS and one with normal folliculogenesis. In the first stage, we established two human GC (hGC) lines by immortalizing them through retrovirus-mediated transfer of the human telomerase reverse transcriptase (hTERT) and c-Myc genes. Subsequently, the normal and PCOS cell lines were characterized and were investigated for their growth features. The cell lines were also examined in terms of immortal markers of hTERT, follicle stimulating hormone receptor (FSHR), aromatase, anti-Müllerian hormone (AMH), growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15), estrogen, and progesterone. Our results indicated that the normal and PCOS cell lines both showed similar characteristics to GCs during the follicular stage in normal and PCOS women. The normal and PCOS cell lines demonstrate molecular mechanisms similar to that of GCs such as folliculogenesis, oogenesis, and steroidogenesis, which enable researchers to perform further investigations in future.

Loss of Both CDKN2A and CDKN2B Allows for Centrosome Overduplication in Melanoma

Centrosomes duplicate only once in coordination with the DNA replication cycle and have an important role in segregating genetic material. In contrast, most cancer cells have centrosome aberrations, including supernumerary centrosomes, and this correlates with aneuploidy and genetic instability. The tumor suppressors p16 (CDKN2A) and p15 (CDKN2B) (encoded by the familial melanoma CDKN2 locus) inhibit CDK4/6 activity and have important roles in cellular senescence. p16 is also associated with suppressing centrosomal aberrations in breast cancer; however, the role of p15 in centrosome amplification is unknown. Here, we investigated the relationship between p15 and p16 expression, centrosome number abnormalities, and melanoma progression in cell lines derived from various stages of melanoma progression. We found that normal human melanocyte lines did not exhibit centrosome number abnormalities, whereas those from later stages of melanoma did. Additionally, under conditions of S-phase block, p15 and p16 status determined whether centrosome overduplication would occur. Indeed, removal of p15 from p16-negative cell lines derived from various stages of melanoma progression changed cells that previously would not overduplicate their centrosomes into cells that did. Although this study used cell lines in vitro, it suggests that, during clinical melanoma progression, sequential loss of p15 and p16 provides conditions for centrosome duplication to become deregulated with consequences for genome instability.

Metastatic Melanoma Patient-Derived Xenografts Respond to MDM2 Inhibition as a Single Agent or in Combination with BRAF/MEK Inhibition

PURPOSE

Over 60% of patients with melanoma respond to immune checkpoint inhibitor (ICI) therapy, but many subsequently progress on these therapies. Second-line targeted therapy is based on BRAF mutation status, but no available agents are available for NRAS, NF1, CDKN2A, PTEN, and TP53 mutations. Over 70% of melanoma tumors have activation of the MAPK pathway due to BRAF or NRAS mutations, while loss or mutation of CDKN2A occurs in approximately 40% of melanomas, resulting in unregulated MDM2-mediated ubiquitination and degradation of p53. Here, we investigated the therapeutic efficacy of over-riding MDM2-mediated degradation of p53 in melanoma with an MDM2 inhibitor that interrupts MDM2 ubiquitination of p53, treating tumor-bearing mice with the MDM2 inhibitor alone or combined with MAPK-targeted therapy.

EXPERIMENTAL DESIGN

To characterize the ability of the MDM2 antagonist, KRT-232, to inhibit tumor growth, we established patient-derived xenografts (PDX) from 15 patients with melanoma. Mice were treated with KRT-232 or a combination with BRAF and/or MEK inhibitors. Tumor growth, gene mutation status, as well as protein and protein-phosphoprotein changes, were analyzed.

RESULTS

One-hundred percent of the 15 PDX tumors exhibited significant growth inhibition either in response to KRT-232 alone or in combination with BRAF and/or MEK inhibitors. Only BRAFV600WT tumors responded to KRT-232 treatment alone while BRAFV600E/M PDXs exhibited a synergistic response to the combination of KRT-232 and BRAF/MEK inhibitors.

CONCLUSIONS

KRT-232 is an effective therapy for the treatment of either BRAFWT or PAN WT (BRAFWT, NRASWT) TP53WT melanomas. In combination with BRAF and/or MEK inhibitors, KRT-232 may be an effective treatment strategy for BRAFV600-mutant tumors.

p53-PHLDA3-Akt Network: The Key Regulators of Neuroendocrine Tumorigenesis

p53 is a well-known tumor suppressor gene and one of the most extensively studied genes in cancer research. p53 functions largely as a transcription factor and can trigger a variety of antiproliferative programs via induction of its target genes. We identified PHLDA3 as a p53 target gene and found that its protein product is a suppressor of pancreatic neuroendocrine tumors (PanNETs) and a repressor of Akt function. PHLDA3 is frequently inactivated by loss of heterozygosity (LOH) and methylation in human PanNETs, and LOH at the PHLDA3 gene locus correlates with PanNET progression and poor prognosis. In addition, in PHLDA3-deficient mice, pancreatic islet cells proliferate abnormally and acquire resistance to apoptosis. In this article, we briefly review the roles of p53 and Akt in human neuroendocrine tumors (NETs) and describe the relationship between the p53-PHLDA3 and Akt pathways. We also discuss the role of PHLDA3 as a tumor suppressor in various NETs and speculate on the possibility that loss of PHLDA3 function may be a useful prognostic marker for NET patients indicating particular drug therapies. These results suggest that targeting the downstream PHLDA3-Akt pathway might provide new therapies to treat NETs.

CDKs in Sarcoma: Mediators of Disease and Emerging Therapeutic Targets

Sarcomas represent one of the most challenging tumor types to treat due to their diverse nature and our incomplete understanding of their underlying biology. Recent work suggests cyclin-dependent kinase (CDK) pathway activation is a powerful driver of sarcomagenesis. CDK proteins participate in numerous cellular processes required for normal cell function, but their dysregulation is a hallmark of many pathologies including cancer. The contributions and significance of aberrant CDK activity to sarcoma development, however, is only partly understood. Here, we describe what is known about CDK-related alterations in the most common subtypes of sarcoma and highlight areas that warrant further investigation. As disruptions in CDK pathways appear in most, if not all, subtypes of sarcoma, we discuss the history and value of pharmacologically targeting CDKs to combat these tumors. The goals of this review are to (1) assess the prevalence and importance of CDK pathway alterations in sarcomas, (2) highlight the gap in knowledge for certain CDKs in these tumors, and (3) provide insight into studies focused on CDK inhibition for sarcoma treatment. Overall, growing evidence demonstrates a crucial role for activated CDKs in sarcoma development and as important targets for sarcoma therapy.

Anti-cancer effects of polyphenols via targeting p53 signaling pathway: updates and future directions

The anticancer effects of polyphenols are ascribed to several signaling pathways including the tumor suppressor gene tumor protein 53 (p53). Expression of endogenous p53 is silent in various types of cancers. A number of polyphenols from a wide variety of dietary sources could upregulate p53 expression in several cancer cell lines through distinct mechanisms of action. The aim of this review is to focus the significance of p53 signaling pathways and to provide molecular intuitions of dietary polyphenols in chemoprevention by monitoring p53 expression that have a prominent role in tumor suppression.

Aberrant expression of embryonic mesendoderm factor MESP1 promotes tumorigenesis

Background

Mesoderm Posterior 1 (MESP1) belongs to the family of basic helix-loop-helix transcription factors. It is a master regulator of mesendoderm development, leading to formation of organs such as heart and lung. However, its role in adult pathophysiology remains unknown. Here, we report for the first time a previously-unknown association of MESP1 with non-small cell lung cancer (NSCLC).

Methods

MESP1 mRNA and protein levels were measured in NSCLC-derived cells by qPCR and immunoblotting respectively. Colony formation assay, colorimetric cell proliferation assay and soft agar colony formation assays were used to assess the effects of MESP1 knockdown and overexpression in vitro. RNA-sequencing and chromatin immunoprecipitation (ChIP)-qPCR were used to determine direct target genes of MESP1. Subcutaneous injection of MESP1-depleted NSCLC cells in immuno-compromised mice was done to study the effects of MESP1 mediated tumor formation in vivo.

Findings

We found that MESP1 expression correlates with poor prognosis in NSCLC patients, and is critical for proliferation and survival of NSCLC-derived cells, thus implicating MESP1 as a lung cancer oncogene. Ectopic MESP1 expression cooperates with loss of tumor suppressor ARF to transform murine fibroblasts. Xenografts from MESP1-depleted cells showed decreased tumor growth in vivo. Global transcriptome analysis revealed a MESP1 DNA-binding-dependent gene signature associated with various hallmarks of cancer, suggesting that transcription activity of MESP1 is most likely responsible for its oncogenic abilities.

Interpretation

Our study demonstrates MESP1 as a previously-unknown lineage-survival oncogene in NSCLC which may serve as a potential prognostic marker and therapeutic target for lung cancer in the future.

Cancer Ecology and Evolution: Positive interactions and system vulnerability

Parallels of cancer with ecology and evolution have provided new insights into the initiation and spread of cancer, and new approaches to therapy. This review describes those parallels while emphasizing some key contrasts. We argue that cancers are less like invasive species than like native species or even crops that have escaped control, and that ecological control and homeo-static control differ fundamentally through both their ends and their means. From our focus on the role of positive interactions in control processes, we introduce a novel mathematical modeling framework that tracks how individual cell lineages arise, and how the many layers of control break down in the emergence of cancer. The next generation of therapies must continue to look beyond cancers as being created by individual renegade cells and address not only the network of interactions those cells inhabit, but the evolutionary logic that created those interactions and their intrinsic vulnerability.

Abnormal Ribosome Biogenesis Partly Induced p53-Dependent Aortic Medial Smooth Muscle Cell Apoptosis and Oxidative Stress

Ribosome biogenesis is a crucial biological process related to cell proliferation, redox balance, and muscle contractility. Aortic smooth muscle cells (ASMCs) show inhibition of proliferation and apoptosis, along with high levels of oxidative stress in aortic dissection (AD). Theoretically, ribosome biogenesis should be enhanced in the ASMCs at its proliferative state but suppressed during apoptosis and oxidative stress. However, the exact status and role of ribosome biogenesis in AD are unknown. We therefore analyzed the expression levels of BOP1, a component of the PeBoW complex which is crucial to ribosome biogenesis, in AD patients and a murine AD model and its influence on the ASMCs. BOP1 was downregulated in the aortic tissues of AD patients compared to healthy donors. In addition, overexpression of BOP1 in human aortic smooth muscle cells (HASMCs) inhibited apoptosis and accumulation of p53 under hypoxic conditions, while knockdown of BOP1 decreased the protein synthesis rate and motility of HASMCs. The RNA polymerase I inhibitor cx-5461 induced apoptosis, ROS production, and proliferative inhibition in the HASMCs, which was partly attenuated by p53 knockout. Furthermore, cx-5461 aggravated the severity of AD in vivo, but a p53-/- background extended the life-span and lowered AD incidence in the mice. Taken together, decreased ribosome biogenesis in ASMCs resulting in p53-dependent proliferative inhibition, oxidative stress, and apoptosis is one of the underlying mechanisms of AD.

Critical Role of Cysteine-Rich Protein 61 in Mediating the Activation of Renal Fibroblasts

Objective

To explore the expression of cysteine-rich protein 61 (Cyr61) in ischemic renal fibrosis and the role of Cyr61 in mediating the activation of renal fibroblasts.

Methods

(1) The rat model of renal fibrosis was established after ischemia-reperfusion acute renal injury (IR-AKI). We detected the renal function by biochemical test, evaluated the fibrosis by Masson staining, and detected the expression of Cyr61 by western blotting. (2) Bioinformatics technique was adopted to analyze the expression of Cyr61 in activated renal fibroblasts. (3) Normal rat kidney fibroblast cells (NRK-49F cells) with over-expression of Cyr61 (Cyr61⁺) and low-expression of it (Cyr61^--) were established by plasmid transfection. Then part of the cells were activated by TGF-β1 and NRK-49F cells were divided into control group, activated group, Cyr61⁺/Cyr61^-- group and Cyr61⁺/Cyr61^-- activated group. The expression of Cyr61 and fibrosis related factors (Col1α1, Col3α1, MMP9, and MMP13) were ascertained by PCR and western blotting. Cell proliferation was discovered by CCK8 method, cell cycle was analyzed by flow cytometry, and the transcription of cell senescence related factors (P53, P21, Rb, and P16) were ascertained by PCR method.

Results

(1) In the process of fibrosis after IR-AKI, the area of collagen fiber was most obviously at AKI 1W, while the Cyr61 protein was at the lowest level at AKI 1W. (2) Gene chip analysis showed that the expression of Cyr61 was decreased in renal fibroblasts after IR. (3) Compared with control group, Cyr61⁺ group expressed less Col1α1 or Col3α1, as well as more MMP9 and MMP13. At the same time, the proliferation of Cyr61⁺ group decreased and cells in G1 phases increased with more transcription of P53, P21, and Rb (all P < 0.05). Compared with activated group, the results of Cyr61⁺ activated group were similar to the above. The above effects of low expression group were just the opposite. In addition, there was no difference in the transcription of P16 among these groups (P > 0.05).

Conclusion

Cyr61 may not only inhibit the fibrotic phenotype of fibroblasts, but may also inhibit proliferation by promoting fibroblasts arrest in G1 phase through the P53/P21/Rb interrelated cell senescence pathway, subsequently affecting the process of ischemic renal fibrosis.

Small molecule activators of the p53 response

Drugging the p53 pathway has been a goal for both academics and pharmaceutical companies since the designation of p53 as the 'guardian of the genome'. Through growing understanding of p53 biology, we can see multiple routes for activation of both wild-type p53 function and restoration of mutant p53. In this review, we focus on small molecules that activate wild-type p53 and that do so in a non-genotoxic manner. In particular, we will describe potential approaches to targeting proteins that alter p53 stability and function through posttranslational modification, affect p53's subcellular localization, or target RNA synthesis or the synthesis of ribonucleotides. The plethora of pathways for exploitation of p53, as well as the wide-ranging response to p53 activation, makes it an attractive target for anti-cancer therapy.

GPRC5A deficiency leads to dysregulated MDM2 via activated EGFR signaling for lung tumor development

GPRC5A, a retinoic acid induced gene, is preferentially expressed in lung tissue. Gprc5a gene deletion leads to spontaneous lung tumor development. However, the mechanism of Gprc5a-mediated lung tumor suppression is not fully understood. Here we showed that MDM2, a p53-negative regulator, was dysregulated in Gprc5a-knockout (ko) mouse tracheal epithelial cells (KO-MTEC) compared to wild type ones. Targeting MDM2 in 1601-a Gprc5a-ko mouse derived lung tumor cell line-and A549-human lung cancer cells, by MDM2 inhibitor Nutlin-3a or small hairpin RNA (sh-RNA)-restored p53 signaling pathway, reduced cancer stem cell markers, and inhibited tumorigenicity. This suggests that dysregulated MDM2 pathway is essential for the oncogenic activities of these cells. MDM2 was found to be stabilized mainly by activated EGFR signaling as targeting EGFR by Erlotinib or sh-RNA repressed MDM2 in a transcription-independent manner. Importantly, overexpression of MDM2 and reduced GPRC5A expression at both protein and mRNA levels were frequently found in clinical human lung cancer tissues. Taken together, GPRC5A deficiency contributes to dysregulated MDM2 via activated EGFR signaling, which promotes lung tumor development.

Siva-1 emerges as a tissue-specific oncogene beyond its classic role of a proapoptotic gene

Siva-1 is a typical apoptotic protein commonly activated by the p53 tumor suppressor protein and should therefore participate in a barrier against the development of cancer. It has proapoptotic activities in various cell systems. Recent findings suggest that Siva-1 possesses several other apoptosis-independent functions and interacts with many other proteins not directly involved in apoptosis. It harbors the ARF E3 ubiquitin protein ligase activity, a property that is clearly prooncogenic and leads to p53 degradation through the upregulation of the Hdm2 protein level. Surprisingly, recent evidence shows that Siva-1 absence prevents the development of non-small cell lung carcinomas in a mouse model and reveals the oncogenic roles in the same types of human cells, indicating its unique function as an oncogene in the cell context-dependent manner. Herein, we review reported activities of Siva-1 in various experimental settings and comment on its ambiguous function in tumor biology.

Autophagy attenuates compression-induced apoptosis of human nucleus pulposus cells via MEK/ERK/NRF1/Atg7 signaling pathways during intervertebral disc degeneration

Autophagy dysfunction has been observed in intervertebral disc degeneration (IVDD) cells, a main contributing factor to cell death, but the precise role of autophagy during IVDD is still controversial. This study aimed to investigate the role of autophagy involved in the pathogenesis of human IVDD and determine the signal transduction pathways responsible for compression-induced autophagy in human nucleus pulposus (NP) cells. Autophagy, suppressing the induction of apoptosis, was activated in NP cells exposed to compression. Molecular analysis showed that compression promoted the activity of NRF1, a transcription regulator increasing Atg7 expression by binding to its promoter, through activating the Ras/MEK/ERK signaling in NP cells. Loss- and gain-of-function studies demonstrate that NRF1 induced autophagy and dampened the apoptotic response by promoting Atg7 expression in NP cells subjected to compression. This study confirmed that compression-induced autophagy could be induced by Ras via MEK/ERK/NRF1/Atg7 signaling pathways, while inhibiting Ras/MEK/ERK/NRF1/Atg7 signaling pathways attenuated this autophagic process, implicating a promising therapeutic strategy for IVDD.

Promoter methylation analysis of CDH1 and p14ARF genes in patients with urothelial bladder cancer

BACKGROUND/AIM

Urothelial bladder cancer arises from the accumulation of multiple epigenetic and genetic changes. We aimed to investigate the specificity and sensitivity of gene-specific promoter methylation of CDH1 and p14ARF genes in the early diagnosis of bladder cancer and compare those with other diagnostic tests in our population.

PATIENTS AND METHODS

In the current study, 65 patients with urothelial bladder cancer and 35 controls without any history of cancer were recruited. Methylation profiles of CDH1 and p14ARF genes from tumor and urine samples were determined by methylation-specific polymerase chain reaction method.

RESULTS

Methylation of CDH1 and p14ARF genes in tumor samples was 95.4% and 78.5%, respectively. The methylation frequencies were found to be 68.8% for CDH1 gene and 72.9% for p14ARF gene in urine samples. Sensitivities of CDH1, p14ARF and urine cytology were found to be 67.4%, 72.1% and 34.9%, respectively, while their specificities were 93.9%, 63.6% and 93.9%, respectively.

CONCLUSION

Aberrant promoter methylation of CDH1 and p14ARF genes can be used to detect urothelial bladder cancer. In low-grade tumors, when compared with urine cytology, combined methylation analysis of CDH1 and p14ARF genes may not increase the sensitivity to identify malignant cells in urine samples.

Aminobenzothiazole derivatives stabilize the thermolabile p53 cancer mutant Y220C and show anticancer activity in p53-Y220C cell lines

Many cancers have the tumor suppressor p53 inactivated by mutation, making reactivation of mutant p53 with small molecules a promising strategy for the development of novel anticancer therapeutics. The oncogenic p53 mutation Y220C, which accounts for approximately 100,000 cancer cases per year, creates an extended surface crevice in the DNA-binding domain, which destabilizes p53 and causes denaturation and aggregation. Here, we describe the structure-guided design of a novel class of small-molecule Y220C stabilizers and the challenging synthetic routes developed in the process. The synthesized chemical probe MB710, an aminobenzothiazole derivative, binds tightly to the Y220C pocket and stabilizes p53-Y220C in vitro. MB725, an ethylamide analogue of MB710, induced selective viability reduction in several p53-Y220C cancer cell lines while being well tolerated in control cell lines. Reduction of viability correlated with increased and selective transcription of p53 target genes such as BTG2, p21, PUMA, FAS, TNF, and TNFRSF10B, which promote apoptosis and cell cycle arrest, suggesting compound-mediated transcriptional activation of the Y220C mutant. Our data provide a framework for the development of a class of potent, non-toxic compounds for reactivating the Y220C mutant in anticancer therapy.

Nucleolar Stress: hallmarks, sensing mechanism and diseases

The nucleolus is a prominent subnuclear compartment, where ribosome biosynthesis takes place. Recently, the nucleolus has gained attention for its novel role in the regulation of cellular stress. Nucleolar stress is emerging as a new concept, which is characterized by diverse cellular insult-induced abnormalities in nucleolar structure and function, ultimately leading to activation of p53 or other stress signaling pathways and alterations in cell behavior. Despite a number of comprehensive reviews on this concept, straightforward and clear-cut way criteria for a nucleolar stress state, regarding the factors that elicit this state, the morphological and functional alterations as well as the rationale for p53 activation are still missing. Based on literature of the past two decades, we herein summarize the evolution of the concept and provide hallmarks of nucleolar stress. Along with updated information and thorough discussion of existing confusions in the field, we pay particular attention to the current understanding of the sensing mechanisms, i.e., how stress is integrated by p53. In addition, we propose our own emphasis regarding the role of nucleolar protein NPM1 in the hallmarks of nucleolar stress and sensing mechanisms. Finally, the links of nucleolar stress to human diseases are briefly and selectively introduced.

GADD45β plays a protective role in acute lung injury by regulating apoptosis in experimental sepsis in vivo

Sepsis is a systemic inflammatory response syndrome due to microbial infection. Growth arrest and DNA-damage-inducible 45 beta (GADD45β) are induced by genotoxic stress and inflammatory cytokines. However, the role of GADD45β during bacterial infection remains unclear. This study was aimed at investigating the role of GADD45β in sepsis. We used GADD45β-knockout (KO) mice and C57BL/6J wild-type (WT) mice. Experimental sepsis was induced by lipopolysaccharide (LPS) administration or cecal ligation and puncture (CLP). Sepsis-induced mortality was higher in GADD45β-KO mice than in WT mice. Histopathological data demonstrated LPS treatment markedly increased lung injury in GADD45β-KO mice as compared to that in WT mice; however, no significant difference was observed in the liver and kidney. Further, mRNA levels of inflammatory cytokines, such as Il-1β, Il-6, Il-10, and Tnf-α, were higher in the lungs of LPS-treated GADD45β-KO mice than in WT mice. Interestingly, plasma levels of these inflammatory cytokines were decreased in LPS-administered GADD45β-KO mice. A significant increase in lung cell apoptosis was observed at early time points in GADD45β-KO mice after administration of LPS as compared to that in WT mice. In line with LPS-induced apoptosis, JNK, and p38 activity was higher in the lung of GADD45β-KO mice at 3 hr after LPS treatment than that in WT mice. In summary, this study is the first to demonstrate the protective role of GADD45β in sepsis and the results suggest that GADD45β could be used as a novel therapeutic target to cure sepsis.

PKC Dependent p14ARF Phosphorylation on Threonine 8 Drives Cell Proliferation

ARF role as tumor suppressor has been challenged in the last years by several findings of different groups ultimately showing that its functions can be strictly context dependent. We previously showed that ARF loss in HeLa cells induces spreading defects, evident as rounded morphology of depleted cells, accompanied by a decrease of phosphorylated Focal Adhesion Kinase (FAK) protein levels and anoikis. These data, together with previous finding that a PKC dependent signalling pathway can lead to ARF stabilization, led us to the hypothesis that ARF functions in cell proliferation might be regulated by phosphorylation. In line with this, we show here that upon spreading ARF is induced through PKC activation. A constitutive-phosphorylated ARF mutant on the conserved threonine 8 (T8D) is able to mediate both cell spreading and FAK activation. Finally, ARF-T8D expression confers growth advantage to cells thus leading to the intriguing hypothesis that ARF phosphorylation could be a mechanism through which pro-proliferative or anti proliferative signals could be transduced inside the cells in both physiological and pathological conditions.

OCT4B regulates p53 and p16 pathway genes to prevent apoptosis of breast cancer cells

Octamer-binding transcription factor 4 (OCT4) is a transcription factor with a well-defined role in stem cell pluripotency. Two OCT4 isoforms, OCT4A and OCT4B, tend to be downregulated as normal cells differentiate. However, OCT4, particularly OCT4B, may become reactivated in cancer cells. Despite this observation, the exact function of OCT4B re-expression in cancer is unclear. In the present study, the role of OCT4 in breast cancer cells was determined. In particular, the ability of OCT4 to regulate key genes involved in cellular proliferation and apoptosis, two pathways that are frequently deregulated in cancer, was examined. The cyclin-dependent kinase inhibitor 2A locus encodes p16INK4a and p14ARF, two important cell cycle inhibitors. The tumor suppressor p53 also has well characterized roles in suppressing proliferation and promoting apoptosis. The present study demonstrated, via overexpression and genetic knockdown techniques, that OCT4B regulates the expression of several of these genes and ultimately regulates the rate of apoptosis of MCF-7 breast cancer cells. It was also observed that, while OCT4B and OCT4A regulate one another, it is OCT4B that serves a more prominent role in regulating the transcription of downstream genes. Taken together, the present results suggest that OCT4B is re-expressed in a number of breast cancer cell lines, where it affects both the transcription of cell cycle genes and the rate of apoptosis. These properties of OCT4B may depend on, at least in part, the co-function of OCT4A.

Investigation of cell cycle-associated structural reorganization in nucleolar FC/DFCs from mouse MFC cells by electron microscopy

Nucleolus structure alters as the cell cycle is progressing. It is established in telophase, maintained throughout the entire interphase and disassembled in metaphase. Fibrillar centers (FCs), dense fibrillar components (DFCs) and granular components (GCs) are essential nucleolar organizations where rRNA transcription and processing and ribosome assembly take place. Hitherto, little is known about the cell cycle-dependent reorganization of these structures. In this study, we followed the nucleolus structure during the cell cycle by electron microscopy (EM). We found the nucleolus experienced multiple rounds of structural reorganization within a single cell cycle: (1) when nucleoli are formed during the transition from late M to G1 phase, FCs, DFCs and GCs are constructed, leading to the establishment of tripartite nucleolus; (2) as FC/DFCs are disrupted at mid-G1, tripartite nucleolus is gradually changed into a bipartite organization; (3) at late G1, the reassembly of FC/DFCs results in a structural transition from bipartite nucleolus towards tripartite nucleolus; (4) as cells enter S phase, FC/DFCs are disassembled again and tripartite nucleolus is thus changed into a bipartite organization. Of note, FC/DFCs were not observed until late S phase; (5) FC/DFCs experience structural disruption and restoration during G2 and (6) when cells are at mitotic stage, FC/DFCs disappear before nucleolus structure is disassembled. These results also suggest that bipartite nucleolus can exist in higher eukaryotes at certain period of the cell cycle. As structures are the fundamental basis of diverse cell activities, unveiling the structural reorganization of nucleolar FCs and DFCs may bring insights into the spatial-temporal compartmentalization of relevant cellular functions.

The long non-coding RNA AK001796 contributes to tumor growth via regulating expression of p53 in esophageal squamous cell carcinoma

Background

Esophageal squamous cell carcinoma (ESCC) is one of the prevalent and deadly cancers worldwide, especially in China. Considering the poor prognosis of ESCC, the aim of this study is to dissect the effects of long non-coding RNA (lncRNA) AK001796 on cell proliferation and cell cycle in vitro and tumorigenicity in vivo, providing therapeutic targets for ESCC.

Methods

We conducted quantitative real time PCR to detect the expression level of lncRNA AK001796 in human ESCC tumor and adjacent non-tumor tissues, and analyzed the correlation between lncRNA AK001796 expression and clinicopathologic feature of ESCC patients. Then we knocked down the expression of lncRNA AK001796 in human ESCC cell lines Eca-109 and TE-1, and next inspected cell cycle and apoptosis condition in these cells using flow cytometry. Subsequently, we used CCK-8 assay to test proliferation ability of the lncRNA AK001796-silenced ESCC cells, and the MDM2/p53 signaling pathway in these cells was analyzed by western blot analysis. At last, the ESCC xenograft models were established to verify the role of lncRNA AK001796 on the occurrence and development of ESCC.

Results

In this study, we demonstrated that lncRNA AK001796 was significantly upregulated in ESCC tumor tissues compared to adjacent non-tumor tissues. Knockdown of lncRNA AK001796 inhibited ESCC cell growth, cell cycle, and tumor growth in a xenograft mouse model via regulating MDM2/p53 signal pathway. The expression of lncRNA AK001796 was positively correlated with MDM2 levels in human ESCC samples.

Conclusions

Overall, lncRNA AK001796 regulates cell proliferation and cell cycle via modulating MDM2/p53 signaling in ESCC, which provides a new insight into the treatment targets for ESCC.

Trial registration This study was registrated in the Ethics Committee of the First Affiliated Hospital of Nanjing Medical University (Trial registration: 2012-SR-127, Registered 20 January 2012)

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0537-8) contains supplementary material, which is available to authorized users.

The Application of Embelin for Cancer Prevention and Therapy

Embelin is a naturally-occurring benzoquinone compound that has been shown to possess many biological properties relevant to human cancer prevention and treatment, and increasing evidence indicates that embelin may modulate various characteristic hallmarks of tumor cells. This review summarizes the information related to the various oncogenic pathways that mediate embelin-induced cell death in multiple cancer cells. The mechanisms of the action of embelin are numerous, and most of them induce apoptotic cell death that may be intrinsic or extrinsic, and modulate the NF-κB, p53, PI3K/AKT, and STAT3 signaling pathways. Embelin also induces autophagy in cancer cells; however, these autophagic cell-death mechanisms of embelin have been less reported than the apoptotic ones. Recently, several autophagy-inducing agents have been used in the treatment of different human cancers, although they require further exploration before being transferred from the bench to the clinic. Therefore, embelin could be used as a potential agent for cancer therapy.

Longitudinal Multiplexed Measurement of Quantitative Proteomic Signatures in Mouse Lymphoma Models Using Magneto-Nanosensors

Cancer proteomics is the manifestation of relevant biological processes in cancer development. Thus, it reflects the activities of tumor cells, host-tumor interactions, and systemic responses to cancer therapy. To understand the causal effects of tumorigenesis or therapeutic intervention, longitudinal studies are greatly needed. However, most of the conventional mouse experiments are unlikely to accommodate frequent collection of serum samples with a large enough volume for multiple protein assays towards single-object analysis. Here, we present a technique based on magneto-nanosensors to longitudinally monitor the protein profiles in individual mice of lymphoma models using a small volume of a sample for multiplex assays. Methods: Drug-sensitive and -resistant cancer cell lines were used to develop the mouse models that render different outcomes upon the drug treatment. Two groups of mice were inoculated with each cell line, and treated with either cyclophosphamide or vehicle solution. Serum samples taken longitudinally from each mouse in the groups were measured with 6-plex magneto-nanosensor cytokine assays. To find the origin of IL-6, experiments were performed using IL-6 knock-out mice. Results: The differences in serum IL-6 and GCSF levels between the drug-treated and untreated groups were revealed by the magneto-nanosensor measurement on individual mice. Using the multiplex assays and mouse models, we found that IL-6 is secreted by the host in the presence of tumor cells upon the drug treatment. Conclusion: The multiplex magneto-nanosensor assays enable longitudinal proteomic studies on mouse tumor models to understand tumor development and therapy mechanisms more precisely within a single biological object.