p53 on the crossroad between regeneration and cancer

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

Integrative Single Cell Atlas Revealed Intratumoral Heterogeneity Generation from an Adaptive Epigenetic Cell State in Human Bladder Urothelial Carcinoma

Intratumor heterogeneity (ITH) of bladder cancer (BLCA) contributes to therapy resistance and immune evasion affecting clinical prognosis. The molecular and cellular mechanisms contributing to BLCA ITH generation remain elusive. It is found that a TM4SF1-positive cancer subpopulation (TPCS) can generate ITH in BLCA, evidenced by integrative single cell atlas analysis. Extensive profiling of the epigenome and transcriptome of all stages of BLCA revealed their evolutionary trajectories. Distinct ancestor cells gave rise to low-grade noninvasive and high-grade invasive BLCA. Epigenome reprograming led to transcriptional heterogeneity in BLCA. During early oncogenesis, epithelial-to-mesenchymal transition generated TPCS. TPCS has stem-cell-like properties and exhibited transcriptional plasticity, priming the development of transcriptionally heterogeneous descendent cell lineages. Moreover, TPCS prevalence in tumor is associated with advanced stage cancer and poor prognosis. The results of this study suggested that bladder cancer interacts with its environment by acquiring a stem cell-like epigenomic landscape, which might generate ITH without additional genetic diversification.

Spatiotemporal multi-omics: exploring molecular landscapes in aging and regenerative medicine

Aging and regeneration represent complex biological phenomena that have long captivated the scientific community. To fully comprehend these processes, it is essential to investigate molecular dynamics through a lens that encompasses both spatial and temporal dimensions. Conventional omics methodologies, such as genomics and transcriptomics, have been instrumental in identifying critical molecular facets of aging and regeneration. However, these methods are somewhat limited, constrained by their spatial resolution and their lack of capacity to dynamically represent tissue alterations. The advent of emerging spatiotemporal multi-omics approaches, encompassing transcriptomics, proteomics, metabolomics, and epigenomics, furnishes comprehensive insights into these intricate molecular dynamics. These sophisticated techniques facilitate accurate delineation of molecular patterns across an array of cells, tissues, and organs, thereby offering an in-depth understanding of the fundamental mechanisms at play. This review meticulously examines the significance of spatiotemporal multi-omics in the realms of aging and regeneration research. It underscores how these methodologies augment our comprehension of molecular dynamics, cellular interactions, and signaling pathways. Initially, the review delineates the foundational principles underpinning these methods, followed by an evaluation of their recent applications within the field. The review ultimately concludes by addressing the prevailing challenges and projecting future advancements in the field. Indubitably, spatiotemporal multi-omics are instrumental in deciphering the complexities inherent in aging and regeneration, thus charting a course toward potential therapeutic innovations.

Understanding the molecular mechanism of regeneration through apoptosis-induced compensatory proliferation studies - updates and future aspects

AICP is a crucial process that maintaining tissue homeostasis and regeneration. In the past, cell death was perceived merely as a means to discard cells without functional consequences. However, during regeneration, effector caspases orchestrate apoptosis, releasing signals that activate stem cells, thereby compensating for tissue loss across various animal models. Despite significant progress, the activation of Wnt3a by caspase-3 remains a focal point of research gaps in AICP mechanisms, spanning from lower to higher regenerative animals. This inquiry into the molecular intricacies of caspase-3-induced Wnt3a activation contributes to a deeper understanding of the links between regeneration and cancer mechanisms. Our report provides current updates on AICP pathways, delineating research gaps and highlighting the potential for future investigations aimed at enhancing our comprehension of this intricate process.

Dietary supplementation with α-ionone alleviates chronic UVB exposure-induced skin photoaging in mice

Photoaging is widely regarded as the most significant contributor to skin aging damage. It is triggered by prolonged exposure to ultraviolet (UV) light and typically manifests as dryness and the formation of wrinkles. Nutritional intervention is a viable strategy for preventing and treating skin photoaging. In previous studies, we demonstrated that α-ionone had ameliorating effects on photoaging in both epidermal keratinocytes and dermal fibroblasts. Here, we investigated the potential anti-photoaging effects of dietary α-ionone using a UVB-irradiated male C57BL/6N mouse model. Our findings provided compelling evidence that dietary α-ionone alleviates wrinkle formation, skin dryness, and epidermal thickening in chronic UVB-exposed mice. α-Ionone accumulated in mouse skin after 14 weeks of dietary intake of α-ionone. α-Ionone increased collagen density and boosted the expression of collagen genes, while attenuating the UVB-induced increase of matrix metalloproteinase genes in the skin tissues. Furthermore, α-ionone suppressed the expression of senescence-associated secretory phenotypes and reduced the expression of the senescence marker p21 and DNA damage marker p53 in the skin of UVB-irradiated mice. Transcriptome sequencing results showed that α-ionone modifies gene expression profiles of skin. Multiple pathway enrichment analyses on both the differential genes and the entire genes revealed that α-ionone significantly affects multiple physiological processes and signaling pathways associated with skin health and diseases, of which the p53 signaling pathway may be the key signaling pathway. Taken together, our findings reveal that dietary α-ionone intervention holds promise in reducing the risks of skin photoaging, offering a potential strategy to address skin aging concerns.

Treatment of Sulfur Mustard Corneal Injury by Augmenting the DNA Damage Response (DDR): A Novel Approach

Sulfur mustard (SM) is a highly reactive organic chemical has been used as a chemical warfare agent and terrorist threat since World War I. The cornea is highly sensitive to SM toxicity and exposure to low vapor doses can cause incapacitating acute injuries. Exposure to higher doses can elicit persistent secondary keratopathies that cause reduced quality of life and impaired or lost vision. Despite a century of research, there are no specific treatments for acute or persistent ocular SM injuries. SM cytotoxicity emerges, in part, through DNA alkylation and double-strand breaks (DSBs). Because DSBs can naturally be repaired by DNA damage response pathways with low efficiency, we hypothesized that enhancing the homologous recombination pathway could pose a novel approach to mitigate SM injury. Here, we demonstrate that a dilithium salt of adenosine diphosphoribose (INV-102) increases protein levels of p53 and Sirtuin 6, upregulates transcription of BRCA1/2, enhances γH2AX focus formation, and promotes assembly of repair complexes at DSBs. Based on in vitro evidence showing INV-102 enhancement of DNA damage response through both p53-dependent and p53-independent pathways, we next tested INV-102 in a rabbit preclinical model of corneal injury. In vivo studies demonstrate a marked reduction in the incidence and severity of secondary keratopathies in INV-102-treated eyes compared with vehicle-treated eyes when treatment was started 24 hours after SM vapor exposure. These results suggest DNA repair mechanisms are a viable therapeutic target for SM injury and suggest topical treatment with INV-102 is a promising approach for SM as well as other conditions associated with DSBs. SIGNIFICANCE STATEMENT: Sulfur mustard gas corneal injury currently has no therapeutic treatment. This study aims to show the therapeutic potential of activating the body's natural DNA damage response to activate tissue repair.

Extracellular Matrix Orchestration of Tissue Remodeling in the Chronically Inflamed Mouse Colon

BACKGROUND & AIMS

Chronic inflammatory illnesses are debilitating and recurrent conditions associated with significant comorbidities, including an increased risk of developing cancer. Extensive tissue remodeling is a hallmark of such illnesses, and is both a consequence and a mediator of disease progression. Despite previous characterization of epithelial and stromal remodeling during inflammatory bowel disease, a complete understanding of its impact on disease progression is lacking.

METHODS

A comprehensive proteomic pipeline using data-independent acquisition was applied to decellularized colon samples from the Muc2 knockout (Muc2KO) mouse model of colitis for an in-depth characterization of extracellular matrix remodeling. Unique proteomic profiles of the matrisomal landscape were extracted from prepathologic and overt colitis. Integration of proteomics and transcriptomics data sets extracted from the same murine model produced network maps describing the orchestrating role of matrisomal proteins in tissue remodeling during the progression of colitis.

RESULTS

The in-depth proteomic workflow used here allowed the addition of 34 proteins to the known colon matrisomal signature. Protein signatures of prepathologic and pathologic colitic states were extracted, differentiating the 2 states by expression of small leucine-rich proteoglycans. We outlined the role of this class and other matrisomal proteins in tissue remodeling during colitis, as well as the potential for coordinated regulation of cell types by matrisomal ligands.

CONCLUSIONS

Our work highlights a central role for matrisomal proteins in tissue remodeling during colitis and defines orchestrating nodes that can be exploited in the selection of therapeutic targets.

Characterisation of forkhead box protein A3 as a key transcription factor for hepatocyte regeneration

Background & Aims

Liver regeneration is vital for the recovery of liver function after injury, yet the underlying mechanism remains to be elucidated. Forkhead box protein A3 (FOXA3), a member of the forkhead box family, plays important roles in endoplasmic reticulum stress sensing, and lipid and glucose homoeostasis, yet its functions in liver regeneration are unknown.

Methods

Here, we explored whether Foxa3 regulates liver regeneration via acute and chronic liver injury mice models. We further characterised the molecular mechanism by chromatin immunoprecipitation sequencing and rescue experiments in vivo and in vitro. Then, we assessed the impact of Foxa3 pharmacological activation on progression and termination of liver regeneration. Finally, we confirmed the Foxa3-Cebpb axis in human liver samples.

Results

Foxa3 is dominantly expressed in hepatocytes and cholangiocytes and is induced upon partial hepatectomy (PH) or carbon tetrachloride (CCl4) administration. Foxa3 deficiency in mice decreased cyclin gene levels and delayed liver regeneration after PH, or acute or chronic i.p. CCl4 injection. Conversely, hepatocyte-specific Foxa3 overexpression accelerated hepatocytes proliferation and attenuated liver damage in an CCl4-induced acute model. Mechanistically, Foxa3 directly regulates Cebpb transcription, which is involved in hepatocyte division and apoptosis both in vivo and in vitro. Of note, Cebpb overexpression in livers of Foxa3-deficient mice rescued their defects in cell proliferation and regeneration upon CCl4 treatment. In addition, pharmacological induction of Foxa3 via cardamonin speeded up hepatocyte proliferation after PH, without interfering with liver regeneration termination. Finally, Cebpb and Ki67 levels had a positive correlation with Foxa3 expression in human chronic disease livers.

Conclusions

These data characterise Foxa3 as a vital regulator of liver regeneration, which may represent an essential factor to maintain liver mass after liver injury by governing Cebpb transcription.

Impact and Implications

Liver regeneration is vital for the recovery of liver function after chemical insults or hepatectomy, yet the underlying mechanism remains to be elucidated. Herein, via in vitro and in vivo models and analysis, we demonstrated that Forkhead box protein A3 (FOXA3), a Forkhead box family member, maintained normal liver regeneration progression by governing Cebpb transcription and proposed cardamonin as a lead compound to induce Foxa3 and accelerate liver repair, which signified that FOXA3 may be a potential therapeutic target for further preclinical study on treating liver injury.

Weighted gene coexpression network analysis and machine learning reveal oncogenome associated microbiome plays an important role in tumor immunity and prognosis in pan-cancer

BACKGROUND

For many years, the role of the microbiome in tumor progression, particularly the tumor microbiome, was largely overlooked. The connection between the tumor microbiome and the tumor genome still requires further investigation.

METHODS

The TCGA microbiome and genome data were obtained from Haziza et al.'s article and UCSC Xena database, respectively. Separate WGCNA networks were constructed for the tumor microbiome and genomic data after filtering the datasets. Correlation analysis between the microbial and mRNA modules was conducted to identify oncogenome associated microbiome module (OAM) modules, with three microbial modules selected for each tumor type. Reactome analysis was used to enrich biological processes. Machine learning techniques were implemented to explore the tumor type-specific enrichment and prognostic value of OAM, as well as the ability of the tumor microbiome to differentiate TP53 mutations.

RESULTS

We constructed a total of 182 tumor microbiome and 570 mRNA WGCNA modules. Our results show that there is a correlation between tumor microbiome and tumor genome. Gene enrichment analysis results suggest that the genes in the mRNA module with the highest correlation with the tumor microbiome group are mainly enriched in infection, transcriptional regulation by TP53 and antigen presentation. The correlation analysis of OAM with CD8+ T cells or TAM1 cells suggests the existence of many microbiota that may be involved in tumor immune suppression or promotion, such as Williamsia in breast cancer, Biostraticola in stomach cancer, Megasphaera in cervical cancer and Lottiidibacillus in ovarian cancer. In addition, the results show that the microbiome-genome prognostic model has good predictive value for short-term prognosis. The analysis of tumor TP53 mutations shows that tumor microbiota has a certain ability to distinguish TP53 mutations, with an AUROC value of 0.755. The tumor microbiota with high importance scores are Corallococcus, Bacillus and Saezia. Finally, we identified a potential anti-cancer microbiota, Tissierella, which has been shown to be associated with improved prognosis in tumors including breast cancer, lung adenocarcinoma and gastric cancer.

CONCLUSION

There is an association between the tumor microbiome and the tumor genome, and the existence of this association is not accidental and could change the landscape of tumor research.

Ectopic PLAG1 induces muscular dystrophy in the mouse

Even though various genetic mutations have been identified in muscular dystrophies (MD), there is still a need to understand the biology of MD in the absence of known mutations. Here we reported a new mouse model of MD driven by ectopic expression of PLAG1. This gene encodes a developmentally regulated transcription factor known to be expressed in developing skeletal muscle, and implicated as an oncogene in certain cancers including rhabdomyosarcoma (RMS), an aggressive soft tissue sarcoma composed of myoblast-like cells. By breeding loxP-STOP-loxP-PLAG1 (LSL-PLAG1) mice into the MCK-Cre line, we achieved ectopic PLAG1 expression in cardiac and skeletal muscle. The Cre/PLAG1 mice died before 6 weeks of age with evidence of cardiomyopathy significantly limiting left ventricle fractional shortening. Histology of skeletal muscle revealed dystrophic features, including myofiber necrosis, fiber size variation, frequent centralized nuclei, fatty infiltration, and fibrosis, all of which mimic human MD pathology. QRT-PCR and Western blot revealed modestly decreased Dmd mRNA and dystrophin protein in the dystrophic muscle, and immunofluorescence staining showed decreased dystrophin along the cell membrane. Repression of Dmd by ectopic PLAG1 was confirmed in dystrophic skeletal muscle and various cell culture models. In vitro studies showed that excess IGF2 expression, a transcriptional target of PLAG1, phenocopied PLAG1-mediated down-regulation of dystrophin. In summary, we developed a new mouse model of a lethal MD due to ectopic expression of PLAG1 in heart and skeletal muscle. Our data support the potential contribution of excess IGF2 in this model. Further studying these mice may provide new insights into the pathogenesis of MD and perhaps lead to new treatment strategies.

Stemness Activity Underlying Whole Brain Regeneration in a Basal Chordate

Understanding how neurons regenerate following injury remains a central challenge in regenerative medicine. Adult mammals have a very limited ability to regenerate new neurons in the central nervous system (CNS). In contrast, the basal chordate Polycarpa mytiligera can regenerate its entire CNS within seven days of complete removal. Transcriptome sequencing, cellular labeling, and proliferation in vivo essays revealed that CNS regeneration is mediated by a newly formed neural progeny and the activation of neurodevelopmental pathways that are associated with enhanced stem-cell activity. Analyzing the expression of 239 activated pathways enabled a quantitative understanding of gene-set enrichment patterns at key regeneration stages. The molecular and cellular mechanisms controlling the regenerative ability that this study reveals can be used to develop innovative approaches to enhancing neurogenesis in closely-related chordate species, including humans.

Single-cell Stereo-seq reveals induced progenitor cells involved in axolotl brain regeneration

The molecular mechanism underlying brain regeneration in vertebrates remains elusive. We performed spatial enhanced resolution omics sequencing (Stereo-seq) to capture spatially resolved single-cell transcriptomes of axolotl telencephalon sections during development and regeneration. Annotated cell types exhibited distinct spatial distribution, molecular features, and functions. We identified an injury-induced ependymoglial cell cluster at the wound site as a progenitor cell population for the potential replenishment of lost neurons, through a cell state transition process resembling neurogenesis during development. Transcriptome comparisons indicated that these induced cells may originate from local resident ependymoglial cells. We further uncovered spatially defined neurons at the lesion site that may regress to an immature neuron-like state. Our work establishes spatial transcriptome profiles of an anamniote tetrapod brain and decodes potential neurogenesis from ependymoglial cells for development and regeneration, thus providing mechanistic insights into vertebrate brain regeneration.

Tumor suppressors inhibit reprogramming of African spiny mouse ( Acomys) fibroblasts to induced pluripotent stem cells

Background: The African spiny mouse ( Acomys) is an emerging mammalian model for scar-free regeneration, and further study of Acomys could advance the field of regenerative medicine. Isolation of pluripotent stem cells from Acomys would allow for development of transgenic or chimeric animals and in vitro study of regeneration; however, the reproductive biology of Acomys is not well characterized, complicating efforts to derive embryonic stem cells. Thus, we sought to generate Acomys induced pluripotent stem cells (iPSCs) by reprogramming somatic cells back to pluripotency. Methods: To generate Acomys iPSCs, we attempted to adapt established protocols developed in Mus. We utilized a PiggyBac transposon system to genetically modify Acomys fibroblasts to overexpress the Yamanaka reprogramming factors as well as mOrange fluorescent protein under the control of a doxycycline-inducible TetON operon system. Results: Reprogramming factor overexpression caused Acomys fibroblasts to undergo apoptosis or senescence. When SV40 Large T antigen (SV40 LT) was added to the reprogramming cocktail, Acomys cells were able to dedifferentiate into pre-iPSCs. Although use of 2iL culture conditions induced formation of colonies resembling Mus PSCs, these Acomys iPS-like cells lacked pluripotency marker expression and failed to form embryoid bodies. An EOS-GiP system was unsuccessful in selecting for bona fide Acomys iPSCs; however, inclusion of Nanog in the reprogramming cocktail along with 5-azacytidine in the culture medium allowed for generation of Acomys iPSC-like cells with increased expression of several naïve pluripotency markers. Conclusions: There are significant roadblocks to reprogramming Acomys cells, necessitating future studies to determine Acomys-specific reprogramming factor and/or culture condition requirements. The requirement for SV40 LT during Acomys dedifferentiation may suggest that tumor suppressor pathways play an important role in Acomys regeneration and that Acomys may possess unreported cancer resistance.

Opposing roles of HDAC6 in liver regeneration and hepatocarcinogenesis

Histone deacetylase 6 (HDAC6), a deacetylase of p53, has emerged as a privileged inhibitory target for cancer therapy because of its deacetylating activity for p53 at K120 and K373/382. However, intricate roles of HDAC6 in hepatocellular carcinogenesis have been suggested by recent evidence, namely that HDAC6 ablation suppresses innate immunity, which plays critical roles in tumor immunosurveillance and antitumor immune responses. Therefore, it is valuable to determine whether HDAC6 ablation inhibits hepatocellular carcinogenesis using in vivo animal models. Here, we firstly showed that HDAC6 ablation increased K320 acetylation of p53, known as pro‐survival acetylation, in all tested animal models but did not always increase K120 and K373/382 acetylation of p53, known as pro‐apoptotic acetylation. HDAC6 ablation induced cellular senescence in primary MEFs and inhibited cell proliferation in HepG2 cells and liver regeneration after two‐thirds partial hepatectomy. However, the genetic ablation of HDAC6 did not inhibit hepatocarcinogenesis, but instead slightly enhanced it in two independent mouse models (DEN + HFD and DEN + TAA). Notably, HDAC6 ablation significantly promoted hepatocarcinogenesis in a multiple DEN treatment hepatocellular carcinoma (HCC) mouse model, mimicking chronic DNA damage in the liver, which correlated with hyperacetylation at K320 of p53 and a decrease in inflammatory cytokines and chemokines. Our data from three independent in vivo animal HCC models emphasize the importance of the complex roles of HDAC6 ablation in hepatocellular carcinogenesis, highlighting its immunosuppressive effects.

We provide the first evidence that HDAC6 is a p53 deacetylase at K320, which is especially important for cancer cell survival in chronic DNA damage conditions. Contrary to the general assumption that HDAC6 inhibition leads to hyperacetylation of p53 at K120, resulting in tumor suppression, our findings from in vivo animal HCC modelsemphasize the importance of the opposing roles of HDAC6 ablation in hepatocellular carcinogenesis by highlighting the K320 acetylation of p53 and immunosuppressive effects.

Banhasasim-Tang Ameliorates Spatial Memory by Suppressing Oxidative Stress through Regulation of ERK/p38 Signaling in Hippocampus of Mice

Since ancient times, Banhasasim-tang (BHS) has been used to treat functional dyspepsia in East Asia. Here, we aimed to determine the protective action of BHS on hippocampal neurons against oxidative stress. We investigated the functional effect of BHS on a scopolamine-induced mouse model, and molecular analysis was performed in glutamate-induced HT22 cells. We observed that BHS administration ameliorated memory dysfunction in scopolamine-treated mice. BHS administration also increased neuronal survival and acetylcholine activity and phosphorylation of extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB) in the hippocampus of mice. In hippocampal cells, BHS treatment rescued glutamate-induced cytotoxicity, apoptosis, and oxidative stress. We observed an increase of HO-1 and a decrease of Nrf2 protein expression in glutamate-induced oxidative stress; however, the expression level of these proteins was significantly rescued by BHS treatment. BHS treatment also regulated phosphorylation of p38, p53, ERK, and CREB. Therefore, our data indicated that BHS may reduce oxidative stress through regulation of ERK-CREB and p38-p53 signaling in the hippocampus, resulting in decreased neuronal damage and improved memory in rodent models of neurodegenerative disease.

TC2N: A Novel Vital Oncogene or Tumor Suppressor Gene In Cancers

Several C2 domain-containing proteins play key roles in tumorigenesis, signal transduction, and mediating protein–protein interactions. Tandem C2 domains nuclear protein (TC2N) is a tandem C2 domain-containing protein that is differentially expressed in several types of cancers and is closely associated with tumorigenesis and tumor progression. Notably, TC2N has been identified as an oncogene in lung and gastric cancer but as a tumor suppressor gene in breast cancer. Recently, a large number of tumor-associated antigens (TAAs), such as heat shock proteins, alpha-fetoprotein, and carcinoembryonic antigen, have been identified in a variety of malignant tumors. Differences in the expression levels of TAAs between cancer cells and normal cells have led to these antigens being investigated as diagnostic and prognostic biomarkers and as novel targets in cancer treatment. In this review, we summarize the clinical characteristics of TC2N-positive cancers and potential mechanisms of action of TC2N in the occurrence and development of specific cancers. This article provides an exploration of TC2N as a potential target for the diagnosis and treatment of different types of cancers.

Santin and cirsimaritin from Betula pubescens and Betula pendula buds induce apoptosis in human digestive system cancer cells

Flavonoids are bioactive secondary metabolites of plants, which exert anti‐cancer effects. However, metabolism in enterocytes and the liver can influence the biological activity of flavonoids contained in the diet. Therefore, results from in vitro studies on cancer cells from the digestive tract and liver may reflect the real effects in the human body. Previously, we have found that the extract from birch buds exerts antiproliferative activity in a panel of cancer cells. In the present study, the anti‐cancer activity of ten flavonoids isolated from the buds of Betula pubescens and Betula pendula was characterized. Among them, santin and cirsimaritin significantly reduced viability, proliferation and clonogenicity of gastric (AGS), colon (DLD‐1) and liver (HepG2) cancer cells. Both flavonoids induced apoptosis, accompanied by activation of caspase‐3, caspase‐7, caspase‐8 and caspase‐9. Moreover, upregulation of p53 was detected only in wild‐type p53 harbouring cells. Together, our results suggest that santin and cirsimaritin exhibit promising anti‐cancer activity in cultures of digestive system cancer cells.

Mutant p53 oncogenicity: dominant-negative or gain-of-function?

The p53 protein is mutated in about 50% of human cancers. Aside from losing its tumor-suppressive activities, mutant p53 may acquire pro-oncogenic activity, which is facilitated by two underlying mechanisms. The first mechanism is the inhibition of co-expressed wild-type p53 (WTp53) activity, dubbed the dominant-negative effect (DNE). The second mechanism is a neomorphic pro-oncogenic activity that does not involve the inhibition of WTp53, termed gain-of-function (GOF). Throughout the years, both mechanisms were demonstrated in a plethora of in vitro and in vivo models. However, whether both account for protumorigenic activities of mutant p53 and in which contexts is still a matter of ongoing debate. Here, we discuss evidence for both DNE and GOF in a variety of models. These models suggest that both GOF and DNE can be relevant, but are highly dependent on the specific mutation type, genetic and cellular context and even the phenotype that is being assessed. In addition, we discuss how mutant and WTp53 might not exist as two separate entities, but rather as a continuum that may involve a balance between the two forms in the same cells, which could be tilted by various factors and drugs. Further elucidation of the factors that dictate the balance between the WT and mutant p53 states, as well as the factors that govern the impact of DNE and GOF in different cancer types, may lead to the development of more effective treatment regimens for cancer patients.

Markers associated with malignant transformation of oral lichen planus: A review article

Oral lichen planus (OLP) is one of the autoimmune diseases associated with chronic inflammation that involves several complications including the potential for malignant transformation into oral squamous cell carcinoma. Pathogenesis of OLP are yet to be fully comprehended however, it has been demonstrated that the epithelial cells in OLP lesions are affected by cytotoxic T lymphocytes leading to immunological reactions. Various factors are reported to act as diagnostic markers for predicting and monitoring the cancerous progression. Hence, in this review, we summarize and present the latest studies regarding the predictive markers associated with malignant potential of OLP.

p53 deficiency triggers dysregulation of diverse cellular processes in physiological oxygen

The mechanisms by which TP53, the most frequently mutated gene in human cancer, suppresses tumorigenesis remain unclear. p53 modulates various cellular processes, such as apoptosis and proliferation, which has led to distinct cellular mechanisms being proposed for p53-mediated tumor suppression in different contexts. Here, we asked whether during tumor suppression p53 might instead regulate a wide range of cellular processes. Analysis of mouse and human oncogene-expressing wild-type and p53-deficient cells in physiological oxygen conditions revealed that p53 loss concurrently impacts numerous distinct cellular processes, including apoptosis, genome stabilization, DNA repair, metabolism, migration, and invasion. Notably, some phenotypes were uncovered only in physiological oxygen. Transcriptomic analysis in this setting highlighted underappreciated functions modulated by p53, including actin dynamics. Collectively, these results suggest that p53 simultaneously governs diverse cellular processes during transformation suppression, an aspect of p53 function that would provide a clear rationale for its frequent inactivation in human cancer.

DAZAP2 acts as specifier of the p53 response to DNA damage

The DNA damage-responsive tumor suppressors p53 and HIPK2 are well established regulators of cell fate decision-making and regulate the cellular sensitivity to DNA-damaging drugs. Here, we identify Deleted in Azoospermia-associated protein 2 (DAZAP2), a small adaptor protein, as a novel regulator of HIPK2 and specifier of the DNA damage-induced p53 response. Knock-down or genetic deletion of DAZAP2 strongly potentiates cancer cell chemosensitivity both in cells and in vivo using a mouse tumour xenograft model. In unstressed cells, DAZAP2 stimulates HIPK2 polyubiquitination and degradation through interplay with the ubiquitin ligase SIAH1. Upon DNA damage, HIPK2 site-specifically phosphorylates DAZAP2, which terminates its HIPK2-degrading function and triggers its re-localization to the cell nucleus. Interestingly, nuclear DAZAP2 interacts with p53 and specifies target gene expression through modulating a defined subset of p53 target genes. Furthermore, our results suggest that DAZAP2 co-occupies p53 response elements to specify target gene expression. Collectively, our findings propose DAZAP2 as novel regulator of the DNA damage-induced p53 response that controls cancer cell chemosensitivity.

Depletion of Trp53 and Cdkn2a Does Not Promote Self-Renewal in the Mammary Gland but Amplifies Proliferation Induced by TNF-α

The mammary epithelium undergoes several rounds of extensive proliferation during the female reproductive cycle. Its expansion is a tightly regulated process, fueled by the mammary stem cells and these cells' unique property of self-renewal. Sufficient new cells have to be produced to maintain the integrity of a tissue, but excessive proliferation resulting in tumorigenesis needs to be prevented. Three well-known tumor suppressors, p53, p16^INK4a, and p19^ARF, have been connected to the limiting of stem cell self-renewal and proliferation. Here we investigate the roles of these three proteins in the regulation of self-renewal and proliferation of mammary epithelial cells. Using mammary epithelial-specific mouse models targeting Trp53 and Cdkn2a, the gene coding for p16^INK4a and p19^ARF, we demonstrate that p53, p16^INK4a, and p19^ARF do not play a significant role in the limitation of normal mammary epithelium self-renewal and proliferation, whereas in the presence of the inflammatory cytokine TNF-α, Trp53^−/−Cdkn2a^−/− mammary basal cells exhibit amplified proliferation.

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p53, p16^INK4a, and p19^ARF do not limit self-renewal of mammary epithelial cells

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p53, p16^INK4a, and p19^ARF do not limit proliferation of mammary epithelial cells

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TNF-α stimulates mammary basal cell organoid formation and proliferation

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Trp53^−/−Cdkn2a^−/− organoids are sensitized to TNF-α-induced proliferation

Induction of genotoxicity and differential alterations of p53 and inflammatory cytokines expression by acute oral exposure to bulk- or nano-calcium hydroxide particles in mice "Genotoxicity of normal- and nano-calcium hydroxide"

With the high increases in the uses of calcium hydroxide in various applications due its distinctive properties, human exposure has increased to normal- and nano-calcium hydroxide. However, its impact on the DNA integrity, expression of inflammatory cytokines, and induction of oxidative stress has not been clearly studied. Therefore, here we estimate the induction of DNA damage, inflammation, and oxidative stress in mice orally administrated a single dose (100 mg/kg) of normal- or nano-sized calcium hydroxide for 24 hour. Comet, Diphenylamine and laddered DNA fragmentation assays were done to assess DNA damage induction. Acute oral administration of normal- or nano-calcium hydroxide particles disrupted the DNA integrity, caused generation of ROS and also concurrent increases in both the nitric oxide concentration and inducible nitric oxide synthase gene expression in a reverse proportional to the calcium hydroxide particles' size. Increases in the concentration of calcium ions as well as alterations in the expression level of p53 and proinflammatory cytokines were also observed in calcium hydroxide administrated groups. Moreover, administration of normal- or nano-calcium hydroxide particles suspension elevated the level of malondialdehyde and decreased both the glutathione peroxidase activity and the reduced glutathione level, as well as caused tissue injuries (e.g. renal tube degeneration, congested blood vessels, atrophied lymphoid follicles, interstitial inflammatory reaction, and hyalinosis of myocardial muscles). Thus, we conclude that calcium hydroxide acutely orally administrated in its ordinary or nano-particulate form causes DNA damage induction by generating free radicals and altering the expression levels of p53 gene and proinflammatory cytokines.

A 3D Cell Culture Model Identifies Wnt/β-Catenin Mediated Inhibition of p53 as a Critical Step during Human Hepatocyte Regeneration

The liver is a highly regenerative organ. While mature hepatocytes under homeostatic conditions are largely quiescent, upon injury, they rapidly enter the cell cycle to recover the damaged tissue. In rodents, a variety of injury models have provided important insights into the molecular underpinnings that govern the proliferative activation of quiescent hepatocytes. However, little is known about the molecular mechanisms of human hepatocyte regeneration and experimental methods to expand primary human hepatocytes (PHH). Here, a 3D spheroid model of PHH is established to study hepatocyte regeneration and integrative time-lapse multi-omics analyses show that upon isolation from the native liver PHH acquire a regenerative phenotype, as seen in vivo upon partial hepatectomy. However, proliferation is limited. By analyzing global promoter motif activities, it is predicted that activation of Wnt/β-catenin and inhibition of p53 signaling are critical factors required for human hepatocyte proliferation. Functional validations reveal that activation of Wnt signaling through external cues alone is sufficient to inhibit p53 and its proliferative senescence-inducing target PAI1 (SERPINE1) and drive proliferation of >50% of all PHH. A scalable 3D culture model is established to study the molecular and cellular biology of human hepatocyte regeneration. By using this model, an essential role of Wnt/β-catenin signaling during human hepatocyte regeneration is identified.

Non-Esterified Fatty Acid-Induced Reactive Oxygen Species Mediated Granulosa Cells Apoptosis Is Regulated by Nrf2/p53 Signaling Pathway

Negative energy balance (NEB) during the perinatal period can affect dairy cow follicular development and reduce the fecundity. Non-esterified fatty acid (NEFA) concentration is elevated during NEB, and is known to be toxic for multiple cell types. In the ovary, NEB increased NEFA, and may influences follicular growth and development. However, the effect and mechanism of NEFA on granulosa cells (GCs) in vitro remains unknown. In this study, we found that NEFA dose-dependently induced apoptosis in primary cultured granulosa cells. Mechanistically, our data showed that NEFA significantly increased reactive oxygen species (ROS) levels, resulting in the activation of endoplasmic reticulum stress (ERS) and eventually cell apoptosis in GCs. Moreover, NEFA also increased the phosphorylation levels of ERK1/2 and p38MAPK pathways, upregulated the expression of p53 and potentially promoted its translocation to the nuclear, thus transcriptionally activated Bax, a downstream gene of this pathway. NEFA also promoted nuclear factor E2 (Nrf2) expression and its level in the nuclear. To elucidate the mechanism of NEFA action, N-acetyl-l-cysteine (NAC), a ROS scavenger was used to verify the role of ROS in NEFA induced apoptosis of GCs. NAC pretreatment reversed the NEFA-induced ERS-related protein and apoptosis-related protein levels. Meanwhile, NAC pretreatment also blocked the phosphorylation of ERK1/2 and p38 induced by NEFA, and the nucleation of Nrf2 and p53, suggesting that ROS plays a crucial role in regulating the NEFA-induced apoptosis of GCs. Together, these findings provide an improved understanding of the mechanisms underlying GCs apoptosis, which could potentially be useful for improving ovarian function.

Multi-scale modeling identifies the role of p53-Gys2 negative feedback loop in cellular homeostasis

The transcription factor p53 is a tumor suppressor and strictly controlled p53 protein abundance coordinates cellular outcomes in response to various stresses. The glycogen synthase 2 (Gys2) and p53 generates a novel negative feedback circuit in which p53 represses Gys2 expression whereas Gys2 can stabilize p53 by competitive binding with MDM2. However, the dynamic role of p53-Gys2 negative feedback is still elusive. In current work, we recapitulated the main experimental findings using multi-scale modeling and emphasized the pivotal role of p53-Gys2 negative feedback loop to main cellular homeostasis. The multi-scale modeling strategy was used to simulate both in vitro and in vivo experimental findings. We found that expression of a key oncoprotein HBx may facilitate cancer progression. Gys2 overexpression can inhibit hepatocellular carcinoma progression whereas Gys2 knockdown advanced cancer development. We also applied oscillatory and impulse disturbance to p53 signaling pathway and the results showed that optimal p53-Gys2 negative feedback loop was highly resistant to oscillatory or impulse disturbances. Instead, the canonical p53-MDM2 negative feedback circuit can significantly affect the dynamics of p53 and therefore effectively shaped pulsatile patterns. Therefore, the dual negative feedback loops in p53 signaling can provide features of both robustness and tunability. These dynamic features are critical for cellular homeostasis against tumor progression in p53 signaling pathway.

Muscle Stem Cells Give Rise to Rhabdomyosarcomas in a Severe Mouse Model of Duchenne Muscular Dystrophy

Most human cancers originate from high-turnover tissues, while low-proliferating tissues, like skeletal muscle, exhibit a lower incidence of tumor development. In Duchenne muscular dystrophy (DMD), which induces increased skeletal muscle regeneration, tumor incidence is increased. Rhabdomyosarcomas (RMSs), a rare and aggressive type of soft tissue sarcoma, can develop in this context, but the impact of DMD severity on RMS development and its cell of origin are poorly understood. Here, we show that RMS latency is affected by DMD severity and that muscle stem cells (MuSCs) can give rise to RMS in dystrophic mice. We report that even before tumor formation, MuSCs exhibit increased self-renewal and an expression signature associated with RMSs. These cells can form tumorspheres in vitro and give rise to RMSs in vivo. Finally, we show that the inflammatory genes Ccl11 and Rgs5 are involved in RMS growth. Together, our results show that DMD severity drives MuSC-mediated RMS development.

MicroRNA-34a deficiency leads to impaired wound closure by augmented inflammation in mice

Background

Proper inflammation resolution is critical for cutaneous wound healing and disordered inflammation resolution results in chronic nonhealing wounds. However, the cellular and molecular mechanisms for resolution of inflammation during skin wound healing are not well understood. MicroRNA-34a is regarded as one tumor suppressor with complexed immune regulatory effects, yet its role during skin wound repair is still unclear.

Methods

Circular full thickness excisional wounds were made on the dorsal skin of C57 mice and miR-34a expression pattern was examined by real time RT-PCR and in situ hybridization. The wound healing rates and histologic morphometric analysis were quantified and compared between wounds treated with antagomir-34a and autologous control antagomir-NC wounds, as well as wounds between miR-34a knockout (KO) and wild type (WT) mice. Immunohistochemistry (IHC) for both MPO and F4/80 were performed to examine the infiltrative neutrophils and macrophages in wounds from miR-34a KO and WT mice. Cytokines including IL-1β, IL-6, TNF-α and IL-10, were detected and analyzed by real time RT-PCR during wound healing. IHC for IL-6 and p-STAT3 were quantified, and WB for p-STAT3 and IL-6R were examined in wounds of miR-34a KO and WT mice.

Results

We found miR-34a was significantly downregulated in the inflammatory phase and back to normal levels in the proliferative phase. Both topical knockdown wounds miR-34a levels by antagomir gel and systematic knockout miR-34a using KO mice resulted in impaired wound healing with delayed re-epithelialization and augmented inflammation. IHC results indicated that there were more residual infiltrative inflammatory cells in the proliferative phase. Moreover, over-activated IL-6/STAT3 signal pathway was identified in the wounds of miR-34a KO mice.

Conclusions

Our findings reveal that miR-34a deficiency augments skin wound inflammation response and leads to impaired wound healing, which suggest that targeted inhibition of miR-34a for tissue repair/regeneration should be with serious consideration.

The role of noncoding RNAs in epithelial cancer

Regulatory noncoding RNAs (ncRNAs) are a class of RNAs transcribed by regions of the human genome that do not encode for proteins. The three main members of this class, named microRNA, long noncoding RNA, and circular RNA play a key role in the regulation of gene expression, eventually shaping critical cellular processes. Compelling experimental evidence shows that ncRNAs function either as tumor suppressors or oncogenes by participating in the regulation of one or several cancer hallmarks, including evading cell death, and their expression is frequently deregulated during cancer onset, progression, and dissemination. More recently, preclinical and clinical studies indicate that ncRNAs are potential biomarkers for monitoring cancer progression, relapse, and response to cancer therapy. Here, we will discuss the role of noncoding RNAs in regulating cancer cell death, focusing on those ncRNAs with a potential clinical relevance.

Lipid desaturation-associated endoplasmic reticulum stress regulates MYCN gene expression in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide due to its high rate of recurrence, in part because of cancer stem cell (CSC)-dependent “field cancerization”. Recently, we identified that the oncogene v-myc avian myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) marked CSC-like subpopulations in heterogeneous HCC and served as a therapeutic target and prognostic marker for HCC. In this study, we explored the molecular basis of upregulated MYCN gene expression in HCC cells. Liquid chromatograph time-of-flight mass spectrometry-based metabolome analysis demonstrated that the content of unsaturated fatty acids was increased in MYCN high expression (MYCN^high) CSC-like HCC cells. Inhibition of lipid desaturation using either the chemical inhibitor or siRNA/shRNA against stearoyl-CoA desaturase-1 (SCD1) suppressed cell proliferation as well as MYCN gene expression in MYCN^high HCC cells, grown as both monolayer and spheres. Further mechanistic study using RNA-seq based transcriptome analysis revealed that endoplasmic reticulum (ER) stress related signaling networks such as endocannabinoid cancer inhibition pathway were under the control of SCD1 in MYCN^high HCC cells. Furthermore, the expression of ER stress-inducible transcription suppressor cyclic AMP-dependent transcription factor (ATF3) was downregulated in MYCN^high CSC-like HCC cells and CSC-rich spheroids, which was upregulated by inhibition of lipid desaturation or treatment with acyclic retinoid (ACR). Lipid profiling using NMR spectroscopy revealed that the ACR dramatically reduced the content of unsaturated fatty acids in HCC cells. The chemical inducer of ER stress inhibited MYCN gene expression, while the chemical inhibitor of ER stress or knockdown of ATF3 gene expression partially rescued the suppression of MYCN gene expression by ACR in MYCN^high HCC cells. These data suggested that lipid desaturation-mediated ER stress signaling regulates MYCN gene expression in HCC cells and serves as a promising therapeutic target for the treatment and prevention of HCC.

Transcriptional Coactivator TAZ Negatively Regulates Tumor Suppressor p53 Activity and Cellular Senescence

Transcriptional coactivator with a PDZ-binding motif (TAZ) is one of the mammalian orthologs of Drosophila Yorkie, a transcriptional coactivator of the Hippo pathway. TAZ has been suggested to function as a regulator that modulates the expression of cell proliferation and anti-apoptotic genes in order to stimulate cell proliferation. TAZ has also been associated with a poor prognosis in several cancers, including breast cancer. However, the physiological role of TAZ in tumorigenesis remains unclear. We herein demonstrated that TAZ negatively regulated the activity of the tumor suppressor p53. The overexpression of TAZ down-regulated p53 transcriptional activity and its downstream gene expression. In contrast, TAZ knockdown up-regulated p21 expression induced by p53 activation. Regarding the underlying mechanism, TAZ inhibited the interaction between p53 and p300 and suppressed the p300-mediated acetylation of p53. Furthermore, TAZ knockdown induced cellular senescence in a p53-dependent manner. These results suggest that TAZ negatively regulates the tumor suppressor functions of p53 and attenuates p53-mediated cellular senescence.

Skin immunity and its dysregulation in atopic dermatitis, hidradenitis suppurativa and vitiligo

While the epidermis is the frontline defense against infections and indeed, it is a peripheral lymphoid organ, the same immunological mechanisms may initiate and sustain pathological conditions. Indeed, a deregulated action against exogenous pathogens could activate a T cell response in atopic dermatitis, hidradenitis suppurativa and vitiligo. Atopic dermatitis (AD) is a chronic inflammatory skin condition with a complex pathophysiology. Although T helper 2 immunity dysregulation is thought to be the main cause of AD etiopathogenesis, the triggering mechanism is not well understood, and the treatment is often difficult. As the AD, hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a dramatic impact on the quality of life of the affected patients. The exact pathophysiology of HS is still unclear, but many evidences report a follicular obstruction and subsequent inflammation with TNF-α, interleukin (IL)-1β, IL-10, and IL-17 involvement. Vitiligo is an autoimmune epidermal disorder which consists of melanocytes destruction and skin depigmentation. Melanocytes destruction is mainly due to their increased oxidative-stress sensitivity with a consequent activation of innate first and adaptative immunity (CD8⁺ T cells) later. The understanding of the triggering mechanisms of AD, HS and Vitiligo is pivotal to outline novel therapies aimed at regaining the physiological immune homeostasis of healthy skin. The aim of this review is to provide new insight on the pathogenesis of these skin diseases and to highlight on the new therapeutic approaches adopted in the treatment of AD, HS and Vitiligo.

Myoblasts rely on TAp63 to control basal mitochondria respiration

p53, with its family members p63 and p73, have been shown to promote myoblast differentiation by regulation of the function of the retinoblastoma protein and by direct activation of p21^Cip/Waf1 and p57^Kip2, promoting cell cycle exit. In previous studies, we have demonstrated that the TAp63γ isoform is the only member of the p53 family that accumulates during in vitro myoblasts differentiation, and that its silencing led to delay in myotube fusion. To better dissect the role of TAp63γ in myoblast physiology, we have generated both sh-p63 and Tet-On inducible TAp63γ clones. Gene array analysis of sh-p63 C2C7 clones showed a significant modulation of genes involved in proliferation and cellular metabolism. Indeed, we found that sh-p63 C2C7 myoblasts present a higher proliferation rate and that, conversely, TAp63γ ectopic expression decreases myoblasts proliferation, indicating that TAp63γ specifically contributes to myoblasts proliferation, independently of p53 and p73. In addition, sh-p63 cells have a defect in mitochondria respiration highlighted by a reduction in spare respiratory capacity and a decrease in complex I, IV protein levels. These results demonstrated that, beside contributing to cell cycle exit, TAp63γ participates to myoblasts metabolism control.

ZNF185 is a p53 target gene following DNA damage

The transcription factor p53 is a key player in the tumour suppressive DNA damage response and a growing number of target genes involved in these pathways has been identified. p53 has been shown to be implicated in controlling cell motility and its mutant form enhances metastasis by loss of cell directionality, but the p53 role in this context has not yet being investigated. Here, we report that ZNF185, an actin cytoskeleton-associated protein from LIM-family of Zn-finger proteins, is induced following DNA-damage. ChIP-seq analysis, chromatin crosslinking immune-precipitation experiments and luciferase assays demonstrate that ZNF185 is a bona fide p53 target gene. Upon genotoxic stress, caused by DNA-damaging drug etoposide and UVB irradiation, ZNF185 expression is up-regulated and in etoposide-treated cells, ZNF185 depletion does not affect cell proliferation and apoptosis, but interferes with actin cytoskeleton remodelling and cell polarization. Bioinformatic analysis of different types of epithelial cancers from both TCGA and GTEx databases showed a significant decrease in ZNF185 mRNA level compared to normal tissues. These findings are confirmed by tissue micro-array IHC staining. Our data highlight the involvement of ZNF185 and cytoskeleton changes in p53-mediated cellular response to genotoxic stress and indicate ZNF185 as potential biomarker for epithelial cancer diagnosis.

ΔNp63 promotes IGF1 signalling through IRS1 in squamous cell carcinoma

Accumulating evidence has proved that deregulation of ΔNp63 expression plays an oncogenic role in head and neck squamous cell carcinomas (HNSCCs). Besides p63, the type 1-insulin-like growth factor (IGF) signalling pathway has been implicated in HNSCC development and progression. Most insulin/IGF1 signalling converges intracellularly onto the protein adaptor insulin receptor substrate-1 (IRS-1) that transmits signals from the receptor to downstream effectors, including the PI3K/AKT and the MAPK kinase pathways, which, ultimately, promote proliferation, invasion, and cell survival. Here we report that p63 directly controls IRS1 transcription and cellular abundance and fosters the PI3K/AKT and MAPK downstream signalling pathways. Inactivation of ΔNp63 expression indeed reduces tumour cell responsiveness to IGF1 stimulation, and inhibits the growth potential of HNSCC cells. In addition, a positive correlation was observed between p63 and IRS1 expression in human HNSCC tissue arrays and in publicly available gene expression data. Our findings indicate that aberrant expression of ΔNp63 in HNSSC may act as an oncogenic stimulus by altering the IGF signalling pathway.

Do Mutations Turn p53 into an Oncogene?

The key role of p53 as a tumor suppressor became clear when it was realized that this gene is mutated in 50% of human sporadic cancers, and germline mutations expose carriers to cancer risk throughout their lifespan. Mutations in this gene not only abolish the tumor suppressive functions of p53, but also equip the protein with new pro-oncogenic functions. Here, we review the mechanisms by which these new functions gained by p53 mutants promote tumorigenesis.

p53-Mediated Tumor Suppression: DNA-Damage Response and Alternative Mechanisms

The tumor suppressor p53 regulates different cellular pathways involved in cell survival, DNA repair, apoptosis, and senescence. However, according to an increasing number of studies, the p53-mediated canonical DNA damage response is dispensable for tumor suppression. p53 is involved in mechanisms regulating many other cellular processes, including metabolism, autophagy, and cell migration and invasion, and these pathways might crucially contribute to its tumor suppressor function. In this review we summarize the canonical and non-canonical functions of p53 in an attempt to provide an overview of the potentially crucial aspects related to its tumor suppressor activity.

Gain-of-Function Mutant p53: All the Roads Lead to Tumorigenesis

The p53 protein is mutated in about 50% of human cancers. Aside from losing the tumor-suppressive functions of the wild-type form, mutant p53 proteins often acquire inherent, novel oncogenic functions, a phenomenon termed mutant p53 gain-of-function (GOF). A growing body of evidence suggests that these pro-oncogenic functions of mutant p53 proteins are mediated by affecting the transcription of various genes, as well as by protein-protein interactions with transcription factors and other effectors. In the current review, we discuss the various GOF effects of mutant p53, and how it may serve as a central node in a network of genes and proteins, which, altogether, promote the tumorigenic process. Finally, we discuss mechanisms by which "Mother Nature" tries to abrogate the pro-oncogenic functions of mutant p53. Thus, we suggest that targeting mutant p53, via its reactivation to the wild-type form, may serve as a promising therapeutic strategy for many cancers that harbor mutant p53. Not only will this strategy abrogate mutant p53 GOF, but it will also restore WT p53 tumor-suppressive functions.

TPP-related mitochondrial targeting copper (II) complex induces p53-dependent apoptosis in hepatoma cells through ROS-mediated activation of Drp1

Background

In recent years, copper complexes have gradually become the focus of potential anticancer drugs due to their available redox properties and low toxicity. In this study, a novel mitochondrion-targeting copper (II) complex, [Cu (ttpy-tpp)Br₂] Br (simplified as CTB), is first synthesized by our group. CTB with tri-phenyl-phosphine (TPP), a targeting and lipophilic group, can cross the cytoplasmic and mitochondrial membranes of tumor cells. The present study aims to investigate how CTB affects mitochondrial functions and exerts its anti-tumor activity in hepatoma cells.

Methods

Multiple molecular experiments including Flow cytometry, Western blot, Immunofluorescence, Tracker staining, Transmission Electron Microscopy and Molecular docking simulation were used to elucidate the underlying mechanisms. Human hepatoma cells were subcutaneously injected into right armpit of male nude mice for evaluating the effects of CTB in vivo.

Results

CTB induced apoptosis via collapse of mitochondrial membrane potential (MMP), ROS production, Bax mitochondrial aggregation as well as cytochrome c release, indicating that CTB-induced apoptosis was associated with mitochondrial pathway in human hepatoma cells. Mechanistic study revealed that ROS-related mitochondrial translocation of p53 was involved in CTB-mediated apoptosis. Simultaneously, elevated mitochondrial Drp1 levels were also observed, and interruption of Drp1 activation played critical role in p53-dependent apoptosis. CTB also strongly suppressed the growth of liver cancer xenografts in vivo.

Conclusion

In human hepatoma cells, CTB primarily induces mitochondrial dysfunction and promotes accumulation of ROS, leading to activation of Drp1. These stimulation signals accelerate mitochondrial accumulation of p53 and lead to the eventual apoptosis. Our research shows that CTB merits further evaluation as a chemotherapeutic agent for the treatment of Hepatocellular carcinoma (HCC).

TAp73 regulates ATP7A: possible implications for ageing-related diseases

The p53 family member p73 controls a wide range of cellular function. Deletion of p73 in mice results in increased tumorigenesis, infertility, neurological defects and altered immune system. Despite the extensive effort directed to define the molecular underlying mechanism of p73 function a clear definition of its transcriptional signature and the extent of overlap with the other p53 family members is still missing. Here we describe a novel TAp73 target, ATP7A a member of a large family of P-type ATPases implicated in human neurogenerative conditions and cancer chemoresistance. Modulation of TAp73 expression influences basal expression level of ATP7A in different cellular models and chromatin immunoprecipitation confirmed a physical direct binding of TAp73 on ATP7A genomic regions. Bioinformatic analysis of expression profile datasets of human lung cancer patients suggests a possible implication of TAp73/ATP7A axis in human cancer. These data provide a novel TAp73-dependent target which might have implications in ageing-related diseases such as cancer and neurodegeneration.

Biomarkers for vascular ageing in aorta tissues and blood samples

OBJECTIVES

Functional and quantitative alterations and senescence of circulating and expanded endothelial progenitor cells (EPC), as well as systemic and tissue modifications of angiogenetic and inflammatory molecules, were evaluated for predicting age-related vessel wall remodeling, correlating them to intima media thickness (IMT) in the common carotid artery (CCA), a biomarker of early cardiovascular disease and aortic root dilation.

POPULATIONS AND METHODS

A homogenous Caucasian population was included in the study, constituted by 160 healthy subjects (80 old subjects, mean age 72 ± 6.4, range 66-83 years; and 80 younger blood donors, mean age 26.2 ± 3.4, range 21-33 years), and 60 old subjects (mean age 73 ± 1.4 (range 66-83) years) with aortic root dilatation and hypertension, and 60 old people (70 ± 2.8 (age range 66-83)) with sporadic ascending aorta aneurysm (AAA). In addition, 20 control individuals (10 men and 10 women, mean age: 65 ± 8), were also included in the study for evaluating the gene expression's levels, in aorta tissues. Appropriate techniques, practises, protocols, gating strategies and statistical analyses were performed in our evaluations.

RESULTS

Interestingly, old people had a significantly reduced functionality and a high grade of senescence (high SA-β-Gal activity and high levels of TP53, p21 and p16 genes) of EPC expanded than younger subjects. The values of related parameters progressively augmented from the old subjects, in good healthy shape, to subjects with hypertension and aorta dilation, and AAA. Moreover, they significantly impacted the endothelium than the alterations in EPC number. No changes, but rather increased systemic levels of VEGF and SDF-1 were also assessed in old people vs. younger donors. Old people also showed significantly increased systemic levels of inflammatory cytokines, and a reciprocal significant reduction of systemic s-Notch 1 than younger subjects. These parameters, also including the number EPC alterations, resulted to be significantly sustained in old people bearers of an inflammatory combined genotype. Consistent with these data, a reduced expression of Notch-1 gene, accompanied by a sustained expression of inflammatory genes (i.e. TLR4, IL-1β, IL-6 and IL-17) were detected in aortic tissues from old control people and AAA cases. Finally, we detected the biological effects induced by all the detected alterations on vessel wall age-related remodeling, by evaluating the IMT in the population studied and correlating it to these alterations. The analysis demonstrated that the unique independent risk predictors for vascular ageing are age, the EPC reduced migratory activity and senescence, high grade of expression of genes inducing EPC senescence and chronic tissue and systemic inflammation.

CONCLUSIONS

Thus, we propose these parameters, of easy determination in biological samples (i.e. blood and tissue samples) from alive human population, as optimal biomarkers for vascular ageing.

Skin immunity and its dysregulation in psoriasis

The skin is a peripheral lymphoid organ, being the first immunological defense against infections as the initial interface between the organism and the external background. The maintenance of the skin immune homeostasis depends on a finely equilibrium of well-regulated relations between different cells and exogenous pathogens. Inflammatory skin diseases are directly linked to the dysregulation of this equilibrium. The present review discusses the role of the immune system, of T cells, in the etiopathogenesis of psoriasis, illustrating a potential rationale for innovative therapeutic intervention.

Multi-omics profiling of calcium-induced human keratinocytes differentiation reveals modulation of unfolded protein response signaling pathways

By proteomic, metabolomic and transcriptomic approaches we shed light on the molecular mechanism by which human keratinocytes undergo to terminal differentiation upon in vitro calcium treatment. Proteomic analysis revealed a selective induction of the ribosomal proteins RSSA, an inhibitor of cell proliferation and inducer of differentiation, HSP 60, a protein folding chaperone and GRP78, an unfolding protein response signal. Additionally, we observed an induction of EF1D, a transcription factor for genes that contain heat-shock responsive elements. Conversely, RAD23, a protein involved in regulating ER-associated protein degradation was down-regulated. All these modifications indicated an ER stress response, which in turn activated the unfolded protein response signaling pathway through ATF4, as confirmed both by the modulation of amino acids metabolism genes, such as XBP1, PDI and GPR78, and by the metabolomic analysis. Finally, we detected a reduction of PDI protein, as confirmed by the increase of oxidized glutathione. Metabolome analysis indicated that glycolysis failed to fuel the Krebs cycle, which continued to decrease during differentiation, at glance with the PPP pathway, allowing NADH production and glutathione reduction. Since unfolded protein response is linked to keratinization, these results may be useful for studying pathological mechanisms as well as potential treatments for different pathological conditions. Abbreviation: UPR, unfolded protein response; HEK, human epidermal keratinocytes; HKGS, human keratinocytes growth factor.

p63 at the Crossroads between Stemness and Metastasis in Breast Cancer

After lung cancer, breast cancer (BC) is the most frequent cause of cancer death among women, worldwide. Although advances in screening approaches and targeted therapeutic agents have decreased BC incidence and mortality, over the past five years, triple-negative breast cancer (TNBC) remains the breast cancer subtype that displays the worst prognosis, mainly due to the lack of clinically actionable targets. Genetic and molecular profiling has unveiled the high intrinsic heterogeneity of TNBC, with the basal-like molecular subtypes representing the most diffuse TNBC subtypes, characterized by the expression of basal epithelial markers, such as the transcription factor p63. In this review, we will provide a broad picture on the physiological role of p63, in maintaining the basal epithelial identity, as well as its involvement in breast cancer progression, emphasizing its relevance in tumor cell invasion and stemness.

Smyd2 conformational changes in response to p53 binding: role of the C-terminal domain

Smyd2 lysine methyltransferase regulates monomethylation of histone and nonhistone lysine residues using S‐adenosylmethionine cofactor as the methyl donor. The nonhistone interactors include several tumorigenic targets, including p53. Understanding this interaction would allow the structural principles that underpin Smyd2‐mediated p53 methylation to be elucidated. Here, we performed μ‐second molecular dynamics (MD) simulations on binary Smyd2‐cofactor and ternary Smyd2‐cofactor‐p53 peptide complexes. We considered both unmethylated and monomethylated p53 peptides (at Lys370 and Lys372). The results indicate that (a) the degree of conformational freedom of the C‐terminal domain of Smyd2 is restricted by the presence of the p53 peptide substrate, (b) the Smyd2 C‐terminal domain shows distinct dynamic properties when interacting with unmethylated and methylated p53 peptides, and (c) Lys372 methylation confines the p53 peptide conformation, with detectable influence on Lys370 accessibility to the cofactor. These MD results are therefore of relevance for studying the biology of p53 in cancer progression.

The different expression of tumor suppressors, RASSF1A, RUNX3, and GSTP1, in patients with alcoholic steatohepatitis (ASH) vs non-alcoholic steatohepatitis (NASH)

As the fifth most common cancer and the second leading cause of cancer related deaths worldwide, hepatocellular carcinoma (HCC) causes up to one million deaths annually. Alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH) are becoming the two major risk factors because both may develop liver fibrosis and hepatocellular carcinoma (HCC) if left untreated. However, compared with 3-10% of patients with ASH may progress to HCC annually, about only 0.5% NASH patients may progress to HCC annually. The present study is to clarify the protein expression differences of tumor suppressor genes (TSGs) between ASH and NASH. In liver biopsied specimens from NASH and ASH patients, using an immunofluorescence method and morphometrically quantitating the fluorescence intensity, we studied the protein expression within hepatocytes cytoplasm of candidate TSGs including RUNX3, GSTP1, and RASSF1A. Compared with the control group of patients, the expression levels of all three proteins were upregulated in the ASH group of patients (p < .001 in all molecules). While RUNX3 was upregulated, GSTP1 and RASSF1 did not change in the NASH group of patients. The most important finding is that compared with the ASH group of patients, the expression levels of all three TSG proteins, RUNX3, GSTP1, and RASSF1, were significantly lower in the NASH group of patients (p < .001 in all three molecules). These results confirmed our previous finding that there are significant differences of many molecules including TSGs that changed in NASH compared to ASH. Thus, we conclude that there are significantly different TSGs and pathways involved during the pathogenesis of HCC development in NASH compared to ASH that may help to develop different strategies for prevention and treatment of NASH and ASH patients.

ΔNp63 in squamous cell carcinoma: defining the oncogenic routes affecting epigenetic landscape and tumour microenvironment

Squamous cell carcinoma (SCC) is a treatment‐refractory tumour which arises from the epithelium of diverse anatomical sites such as oesophagus, head and neck, lung and skin. Accumulating evidence has revealed a number of genomic, clinical and molecular features commonly observed in SCC of distinct origins. Some of these genetic events culminate in fostering the activity of ΔNp63, a potent oncogene which exerts its pro‐tumourigenic effects by regulating specific transcriptional programmes to sustain malignant cell proliferation and survival. In this review, we will describe the genetic and epigenetic determinants underlying ΔNp63 oncogenic activities in SCC, and discuss some relevant transcriptional effectors of ΔNp63, emphasizing their impact in modulating the crosstalk between tumour cells and tumour microenvironment (TME).

SSRP1 promotes colorectal cancer progression and is negatively regulated by miR-28-5p

In this study, microarray data analysis, real‐time quantitative PCR and immunohistochemistry were used to detect the expression levels of SSRP1 in colorectal cancer (CRC) tissue and in corresponding normal tissue. The association between structure‐specific recognition protein 1 (SSRP1) expression and patient prognosis was examined by Kaplan‐Meier analysis. SSRP1 was knocked down and overexpressed in CRC cell lines, and its effects on proliferation, cell cycling, migration, invasion, cellular energy metabolism, apoptosis, chemotherapeutic drug sensitivity and cell phenotype‐related molecules were assessed. The growth of xenograft tumours in nude mice was also assessed. MiRNAs that potentially targeted SSRP1 were determined by bioinformatic analysis, Western blotting and luciferase reporter assays. We showed that SSRP1 mRNA levels were significantly increased in CRC tissue. We also confirmed that this upregulation was related to the terminal tumour stage in CRC patients, and high expression levels of SSRP1 predicted shorter disease‐free survival and faster relapse. We also found that SSRP1 modulated proliferation, metastasis, cellular energy metabolism and the epithelial‐mesenchymal transition in CRC. Furthermore, SSRP1 induced apoptosis and SSRP1 knockdown augmented the sensitivity of CRC cells to 5‐fluorouracil and cisplatin. Moreover, we explored the molecular mechanisms accounting for the dysregulation of SSRP1 in CRC and identified microRNA‐28‐5p (miR‐28‐5p) as a direct upstream regulator of SSRP1. We concluded that SSRP1 promotes CRC progression and is negatively regulated by miR‐28‐5p.