A Glance of p53 Functions in Brain Development, Neural Stem Cells, and Brain Cancer

Human cortical neurogenesis is altered via glucocorticoid-mediated regulation of ZBTB16 expression

Glucocorticoids are important for proper organ maturation, and their levels are tightly regulated during development. Here, we use human cerebral organoids and mice to study the cell-type-specific effects of glucocorticoids on neurogenesis. We show that glucocorticoids increase a specific type of basal progenitors (co-expressing PAX6 and EOMES) that has been shown to contribute to cortical expansion in gyrified species. This effect is mediated via the transcription factor ZBTB16 and leads to increased production of neurons. A phenome-wide Mendelian randomization analysis of an enhancer variant that moderates glucocorticoid-induced ZBTB16 levels reveals causal relationships with higher educational attainment and altered brain structure. The relationship with postnatal cognition is also supported by data from a prospective pregnancy cohort study. This work provides a cellular and molecular pathway for the effects of glucocorticoids on human neurogenesis that relates to lasting postnatal phenotypes.

Hyaluronic Acid Prevents Fusion of Brain Tumor-Derived Spheroids and Selectively Alters Their Gene Expression Profile

Hyaluronic acid (HA), a major glycosaminoglycan of the brain extracellular matrix, modulates cell behaviors through binding its receptor, Cd44. In this study, we assessed the influence of HA on high-grade brain tumors in vitro. The model comprised cell cultures derived from six rodent carcinogen-induced brain tumors, forming 3D spheroids prone to spontaneous fusion. Supplementation of the standard culture medium with 0.25% HA significantly inhibited the fusion rates, preserving the shape and size uniformity of spheroids. The 3D cultures were assigned to two groups; a Cd44lo group had a tenfold decreased relative expression of Cd44 than another (Cd44hi) group. In addition, these two groups differed by expression levels of Sox2 transcription factor; the correlation analysis revealed a tight negative association for Cd44 and Sox2. Transcriptomic responses of spheroids to HA exposure also depended on Cd44 expression levels, from subtle in Cd44lo to more pronounced and specific in Cd44hi, involving cell cycle progression, PI3K/AKT/mTOR pathway activation, and multidrug resistance genes. The potential HA-induced increase in brain tumor 3D models' resistance to anticancer drug therapy should be taken into account when designing preclinical studies using HA scaffold-based models. The property of HA to prevent the fusion of brain-derived spheroids can be employed in CNS regenerative medicine and experimental oncology to ensure the production of uniform, controllably fusing neurospheres when creating more accurate in vitro brain models.

Cockayne Syndrome Patient iPSC-Derived Brain Organoids and Neurospheres Show Early Transcriptional Dysregulation of Biological Processes Associated with Brain Development and Metabolism

Cockayne syndrome (CS) is a rare hereditary autosomal recessive disorder primarily caused by mutations in Cockayne syndrome protein A (CSA) or B (CSB). While many of the functions of CSB have been at least partially elucidated, little is known about the actual developmental dysregulation in this devasting disorder. Of particular interest is the regulation of cerebral development as the most debilitating symptoms are of neurological nature. We generated neurospheres and cerebral organoids utilizing Cockayne syndrome B protein (CSB)-deficient induced pluripotent stem cells derived from two patients with distinct severity levels of CS and healthy controls. The transcriptome of both developmental timepoints was explored using RNA-Seq and bioinformatic analysis to identify dysregulated biological processes common to both patients with CS in comparison to the control. CSB-deficient neurospheres displayed upregulation of the VEGFA-VEGFR2 signalling pathway, vesicle-mediated transport and head development. CSB-deficient cerebral organoids exhibited downregulation of brain development, neuron projection development and synaptic signalling. We further identified the upregulation of steroid biosynthesis as common to both timepoints, in particular the upregulation of the cholesterol biosynthesis branch. Our results provide insights into the neurodevelopmental dysregulation in patients with CS and strengthen the theory that CS is not only a neurodegenerative but also a neurodevelopmental disorder.

State of the Art of Pharmacological Activators of p53 in Ocular Malignancies

The pivotal role of p53 in the regulation of a vast array of cellular functions has been the subject of extensive research. The biological activity of p53 is not strictly limited to cell cycle arrest but also includes the regulation of homeostasis, DNA repair, apoptosis, and senescence. Thus, mutations in the p53 gene with loss of function represent one of the major mechanisms for cancer development. As expected, due to its key role, p53 is expressed throughout the human body including the eye. Specifically, altered p53 signaling pathways have been implicated in the development of conjunctival and corneal tumors, retinoblastoma, uveal melanoma, and intraocular melanoma. As non-selective cancer chemotherapies as well as ionizing radiation can be associated with either poor efficacy or dose-limiting toxicities in the eye, reconstitution of the p53 signaling pathway currently represents an attractive target for cancer therapy. The present review discusses the role of p53 in the pathogenesis of these ocular tumors and outlines the various pharmacological activators of p53 that are currently under investigation for the treatment of ocular malignancies.

miR-491-5p regulates the susceptibility of glioblastoma to ferroptosis through TP53

BACKGROUND

Ferroptosis has excellent potential in glioblastoma (GBM) therapy. In this study, we attempted to explore the effect of miR 491-5p on ferroptosis in GBM.

METHODS

In this study, publicly available ferroptosis-related genome maps were used to screen genes upregulated in GBM and their target genes. The Spearman correlation coefficient was applied to analyze the correlation between the tumor protein p53 gene (TP53) and miR-491-5p. The expressions of miR-491-5p and TP53 were determined. The protein abundances of the TP53-encoded factors p53 and p21 were measured. Cell proliferation, migration and invasion were assessed. We pretreated U251MG cells and GBM mice with a ferroptosis inducer (erastin). The mitochondrial state was observed. The contents of reactive oxygen species (ROS), total Fe and Fe²⁺ were calculated.

RESULTS

The level of TP53 was significantly increased in GBM and negatively correlated with miR-491-5p. miR-491-5p overexpression promoted U251MG cell proliferation, migration and invasion and interfered with the p53/p21 pathway. TP53 supplement reversed the effects of miR-491-5p. U251MG cells and GBM mice exhibited significant accumulations of ROS and iron. Erastin promoted the expression of TP53. Inhibition of TP53 reversed erastin-induced physiological phenotypes. Moreover, miR-491-5p overexpression caused a decrease in the number of damaged mitochondria and the contents of ROS, total Fe and Fe²⁺. TP53 supplement disrupted miR-491-5p-repressed ferroptosis. Erastin could inhibit GBM growth, and miR-491-5p overexpression impeded the therapeutic effect of erastin.

CONCLUSIONS

Our findings reveal the functional diversity of miR-491-5p in GBM and suggest that miR-491-5p/TP53 signaling hinders the sensitivity of GBM to ferroptosis through the p53/p21 pathway.

Study of MDM2 as Prognostic Biomarker in Brain-LGG Cancer and Bioactive Phytochemicals Inhibit the p53-MDM2 Pathway: A Computational Drug Development Approach

An evaluation of the expression and predictive significance of the MDM2 gene in brain lower-grade glioma (LGG) cancer was carried out using onco-informatics pipelines. Several transcriptome servers were used to measure the differential expression of the targeted MDM2 gene and search mutations and copy number variations. GENT2, Gene Expression Profiling Interactive Analysis, Onco-Lnc, and PrognoScan were used to figure out the survival rate of LGG cancer patients. The protein–protein interaction networks between MDM2 gene and its co-expressed genes were constructed by Gene-MANIA tool. Identified bioactive phytochemicals were evaluated through molecular docking using Schrödinger Suite Software, with the MDM2 (PDB ID: 1RV1) target. Protein–ligand interactions were observed with key residues of the macromolecular target. A molecular dynamics simulation of the novel bioactive compounds with the targeted protein was performed. Phytochemicals targeting MDM2 protein, such as Taxifolin and (-)-Epicatechin, have been shown with more highly stable results as compared to the control drug, and hence, concluded that phytochemicals with bioactive potential might be alternative therapeutic options for the management of LGG patients. Our once informatics-based designed pipeline has indicated that the MDM2 gene may have been a predictive biomarker for LGG cancer and selected phytochemicals possessed outstanding interaction results within the macromolecular target’s active site after utilizing in silico approaches. In vitro and in vivo experiments are recommended to confirm these outcomes.

Fighting secondary triple-negative breast cancer in cerebellum: A powerful aid from a medicinal mushrooms blend

Breast cancer (BC) is the second most common cause of brain metastasis onset in patients, with the cerebellum accounting for the 33% of cases. In the current study, using a 4T1 triple-negative mouse BC model, we revealed that an orally administered medicinal mushrooms (MM) blend, rich in β-glucans, played a direct and specific anti-cancer action on cerebellar metastases, also bettering locomotor performances. The neuroprotective effect of the MM blend plays through (i) a direct and specific inhibition of cerebellar metastatization pattern typical of TNBC (with an induced reduction of about 50% of metastases density) and (ii) the regulation of apoptosis and proliferation-related genes, as suggested by expression changes of specific molecular markers, i.e. PCNA, p53, Bcl2, BAX, CASP9, CASP3, Hsp70 and AIF. Therefore, inhibiting the metastatization process, triggering a significant apoptosis increase, and lessening cell proliferation, this MM supplement, employed as adjuvant treatment in association with conventional therapy, could represent a promising approach, in the field of Integrative Oncology, for patients' management in both prevention and treatment of brain metastases from BC.

Regulation of the p53‑mediated ferroptosis signaling pathway in cerebral ischemia stroke (Review)

Stroke is one of the most threatening diseases worldwide, particularly in countries with larger populations; it is associated with high morbidity, mortality and disability rates. As a result, extensive research efforts are being made to address these issues. Stroke can include either hemorrhagic stroke (blood vessel ruptures) or ischemic stroke (blockage of an artery). Whilst the incidence of stroke is higher in the elderly population (≥65), it is also increasing in the younger population. Ischemic stroke accounts for ~85% of all stroke cases. The pathogenesis of cerebral ischemic injury can include inflammation, excitotoxic injury, mitochondrial dysfunction, oxidative stress, ion imbalance and increased vascular permeability. All of the aforementioned processes have been extensively studied, providing insights into the disease. Other clinical consequences observed include brain edema, nerve injury, inflammation, motor deficits and cognitive impairment, which not only cause disabilities obstructing daily life but also increase the mortality rates. Ferroptosis is a type of cell death that is characterized by iron accumulation and increased lipid peroxidation in cells. In particular, ferroptosis has been previously implicated in ischemia-reperfusion injury in the central nervous system. It has also been identified as a mechanism involved in cerebral ischemic injury. The tumor suppressor p53 has been reported to modulate the ferroptotic signaling pathway, which both positively and negatively affects the prognosis of cerebral ischemia injury. The present review summarizes the recent findings on the molecular mechanisms of ferroptosis under the regulation of p53 underlying cerebral ischemia injury. Understanding of the p53/ferroptosis signaling pathway may provide insights into developing methods for improving the diagnosis, treatment and even prevention of stroke.

Fine-tuning of mTOR signaling by the UBE4B-KLHL22 E3 ubiquitin ligase cascade in brain development

Spatiotemporal regulation of the mechanistic target of rapamycin (mTOR) pathway is pivotal for establishment of brain architecture. Dysregulation of mTOR signaling is associated with a variety of neurodevelopmental disorders. Here, we demonstrate that the UBE4B-KLHL22 E3 ubiquitin ligase cascade regulates mTOR activity in neurodevelopment. In a mouse model with UBE4B conditionally deleted in the nervous system, animals display severe growth defects, spontaneous seizures and premature death. Loss of UBE4B in the brains of mutant mice results in depletion of neural precursor cells and impairment of neurogenesis. Mechanistically, UBE4B polyubiquitylates and degrades KLHL22, an E3 ligase previously shown to degrade the GATOR1 component DEPDC5. Deletion of UBE4B causes upregulation of KLHL22 and hyperactivation of mTOR, leading to defective proliferation and differentiation of neural precursor cells. Suppression of KLHL22 expression reverses the elevated activity of mTOR caused by acute local deletion of UBE4B. Prenatal treatment with the mTOR inhibitor rapamycin rescues neurogenesis defects in Ube4b mutant mice. Taken together, these findings demonstrate that UBE4B and KLHL22 are essential for maintenance and differentiation of the precursor pool through fine-tuning of mTOR activity.

Molecular targeted therapy: A new avenue in glioblastoma treatment

Glioblastoma, also referred to as glioblastoma multiforme (GBM), is grade IV astrocytoma characterized by being fast-growing and the most aggressive brain tumor. In adults, it is the most prevalent type of malignant brain tumor. Despite the advancements in both diagnosis tools and therapeutic treatments, GBM is still associated with poor survival rate without any statistically significant improvement in the past three decades. Patient's genome signature is one of the key factors causing the development of this tumor, in addition to previous radiation exposure and other environmental factors. Researchers have identified genomic and subsequent molecular alterations affecting core pathways that trigger the malignant phenotype of this tumor. Targeting intrinsically altered molecules and pathways is seen as a novel avenue in GBM treatment. The present review shed light on signaling pathways and intrinsically altered molecules implicated in GBM development. It discussed the main challenges impeding successful GBM treatment, such as the blood brain barrier and tumor microenvironment (TME), the plasticity and heterogeneity of both GBM and TME and the glioblastoma stem cells. The present review also presented current advancements in GBM molecular targeted therapy in clinical trials. Profound and comprehensive understanding of molecular participants opens doors for innovative, more targeted and personalized GBM therapeutic modalities.

Pathological implications of metabolic reprogramming and its therapeutic potential in medulloblastoma

Tumor-specific alterations in metabolism have been recognized to sustain the production of ATP and macromolecules needed for cell growth, division and survival in many cancer types. However, metabolic heterogeneity poses a challenge for the establishment of effective anticancer therapies that exploit metabolic vulnerabilities. Medulloblastoma (MB) is one of the most heterogeneous malignant pediatric brain tumors, divided into four molecular subgroups (Wingless, Sonic Hedgehog, Group 3 and Group 4). Recent progresses in genomics, single-cell sequencing, and novel tumor models have updated the classification and stratification of MB, highlighting the complex intratumoral cellular diversity of this cancer. In this review, we emphasize the mechanisms through which MB cells rewire their metabolism and energy production networks to support and empower rapid growth, survival under stressful conditions, invasion, metastasis, and resistance to therapy. Additionally, we discuss the potential clinical benefits of currently available drugs that could target energy metabolism to suppress MB progression and increase the efficacy of the current MB therapies.

Extracellular vesicle miRNAs in breast milk of obese mothers

Background

Breast milk has abundant extracellular vesicles (EVs) containing various biological molecules (cargo), including miRNAs. EVs are not degraded in the gastrointestinal system and circulation; thus, breast milk EVs (bEVs) are expected to interact with other organs in breastfed infants and modify the gene expression of recipient cells using miRNAs. Maternal pre-pregnancy BMI is a critical factor influencing the composition of breast milk. Thus, in mothers with obesity, miRNAs in bEVs can be altered, which might be associated with adverse health outcomes in infants. In this study, we examined 798 miRNAs to determine which miRNAs are altered in the bEVs of mothers with obesity and their potential impact on breastfed infants.

Methods

We recruited healthy nursing mothers who were either of normal weight (BMI < 25) or with obesity (BMI ≥ 30) based on their pre-pregnancy BMI, and delivered a singleton baby in the prior 6 months. EVs were isolated from breast milk with ultracentrifugation. bEV characteristics were examined by flow cytometry and fluorescence imaging of EV markers. A total of 798 miRNAs were screened using a NanoString human miRNA panel to find differentially expressed miRNAs in bEVs of mothers with obesity compared to mothers of normal weight.

Results

We included 65 nursing mothers: 47 of normal weight and 18 with obesity based on pre-pregnancy BMI. After bEV isolation, we confirmed the expression of various EV markers. Out of 37 EV markers, CD326 (EpCaM) was the most highly expressed in bEVs. The most abundant miRNAs in bEVs include miR-30b-5p, miR-4454, miR-494-3p, and let-7 miRNAs. Target genes of the top 10 miRNAs were associated with cancer, prolactin pathway, EGFR, ErbB, and FoxO signaling pathway. In bEVs of mothers with obesity, 19 miRNAs were differentially expressed (adjusted p < 0.05 cut-off), which include miR-575, miR-630, miR-642a-3p, and miR-652-5p. These miRNAs and their target genes were associated with neurological diseases and psychological disorders.

Conclusion

In this study, we characterized bEVs and demonstrated altered miRNAs in bEVs of mothers with obesity and identified the pathways of their potential target genes. Our findings will provide insight for future studies investigating the role of bEVs in breastfed infants.

Identifying a novel ferroptosis-related prognostic score for predicting prognosis in chronic lymphocytic leukemia

Background

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the western world. Although the treatment landscape for CLL is rapidly evolving, there are still some patients who develop drug resistance or disease refractory. Ferroptosis is a type of lipid peroxidation–induced cell death and has been suggested to have prognostic value in several cancers. Our research aims to build a prognostic model to improve risk stratification in CLL patients and facilitate more accurate assessment for clinical management.

Methods

The differentially expressed ferroptosis-related genes (FRGs) in CLL were filtered through univariate Cox regression analysis based on public databases. Least absolute shrinkage and selection operator (LASSO) Cox algorithms were performed to construct a prognostic risk model. CIBERSORT and single-sample gene set enrichment analysis (ssGSEA) were performed to estimate the immune infiltration score and immune-related pathways. A total of 36 CLL patients in our center were enrolled in this study as a validation cohort. Moreover, a nomogram model was established to predict the prognosis.

Results

A total of 15 differentially expressed FRGs with prognostic significance were screened out. After minimizing the potential risk of overfitting, we constructed a novel ferroptosis-related prognostic score (FPS) model with nine FRGs (AKR1C3, BECN1, CAV1, CDKN2A, CXCL2, JDP2, SIRT1, SLC1A5, and SP1) and stratified patients into low- and high-risk groups. Kaplan–Meier analysis showed that patients with high FPS had worse overall survival (OS) (P<0.0001) and treatment-free survival (TFS) (P<0.0001). ROC curves evaluated the prognostic prediction ability of the FPS model. Additionally, the immune cell types and immune-related pathways were correlated with the risk scores in CLL patients. In the validation cohort, the results confirmed that the high-risk group was related to worse OS (P<0.0001), progress-free survival (PFS) (P=0.0140), and TFS (P=0.0072). In the multivariate analysis, only FPS (P=0.011) and CLL-IPI (P=0.010) were independent risk indicators for OS. Furthermore, we established a nomogram including FPS and CLL-IPI that could strongly and reliably predict individual prognosis.

Conclusion

A novel FPS model can be used in CLL for prognostic prediction. The model index may also facilitate the development of new clinical ferroptosis-targeted therapies in patients with CLL.

Emerging roles of ferroptosis in glioma

Glioma is the most common primary malignant tumor in the central nervous system, and directly affects the quality of life and cognitive function of patients. Ferroptosis, is a new form of regulated cell death characterized by iron-dependent lipid peroxidation. Ferroptosis is mainly due to redox imbalance and involves multiple intracellular biology processes, such as iron metabolism, lipid metabolism, and antioxidants synthesis. Induction of ferroptosis could be a new target for glioma treatment, and ferroptosis-related processes are associated with chemoresistance and radioresistance in glioma. In the present review, we provide the characteristics, key regulators and pathways of ferroptosis and the crosstalk between ferroptosis and other programmed cell death in glioma, we also proposed the application and prospect of ferroptosis in the treatment of glioma.

Is extremely low frequency pulsed electromagnetic fields applicable to gliomas? A literature review of the underlying mechanisms and application of extremely low frequency pulsed electromagnetic fields

Gliomas refer to a group of complicated human brain tumors with a low 5-year survival rate and limited therapeutic options. Extremely low-frequency pulsed electromagnetic field (ELF-PEMF) is a specific magnetic field featuring almost no side effects. However, the application of ELF-PEMF in the treatment of gliomas is rare. This review summarizes five significant underlying mechanisms including calcium ions, autophagy, apoptosis, angiogenesis, and reactive oxygen species, and applications of ELF-PEMF in glioma treatment from a clinical practice perspective. In addition, the prospects of ELF-PEMF in combination with conventional therapy for the treatment of gliomas are reviewed. This review benefits any specialists, especially oncologists, interested in this new therapy because it can help treat patients with gliomas properly.

Zika virus induces FOXG1 nuclear displacement and downregulation in human neural progenitors

Congenital alterations in the levels of the transcription factor Forkhead box g1 (FOXG1) coding gene trigger “FOXG1 syndrome,” a spectrum that recapitulates birth defects found in the “congenital Zika syndrome,” such as microcephaly and other neurodevelopmental conditions. Here, we report that Zika virus (ZIKV) infection alters FOXG1 nuclear localization and causes its downregulation, thus impairing expression of genes involved in cell replication and apoptosis in several cell models, including human neural progenitor cells. Growth factors, such as EGF and FGF2, and Thr271 residue located in FOXG1 AKT domain, take part in the nuclear displacement and apoptosis protection, respectively. Finally, by progressive deletion of FOXG1 sequence, we identify the C-terminus and the residues 428–481 as critical domains. Collectively, our data suggest a causal mechanism by which ZIKV affects FOXG1, its target genes, cell cycle progression, and survival of human neural progenitors, thus contributing to microcephaly.

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Zika virus induces FOXG1 displacement and downregulation in human neural progenitors

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FGF2 and EGF prevent FOXG1 displacement induced by Zika virus infection

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Phospho-Thr271 and C-terminal domain of FOXG1 are involved in its mislocalization

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FOXG1 target genes, cell survival, and cell death are affected by Zika virus

Tracing the origins of glioblastoma by investigating the role of gliogenic and related neurogenic genes/signaling pathways in GBM development: a systematic review

Background

Glioblastoma is one of the most aggressive tumors. The etiology and the factors determining its onset are not yet entirely known. This study investigates the origins of GBM, and for this purpose, it focuses primarily on developmental gliogenic processes. It also focuses on the impact of the related neurogenic developmental processes in glioblastoma oncogenesis. It also addresses why glial cells are at more risk of tumor development compared to neurons.

Methods

Databases including PubMed, MEDLINE, and Google Scholar were searched for published articles without any date restrictions, involving glioblastoma, gliogenesis, neurogenesis, stemness, neural stem cells, gliogenic signaling and pathways, neurogenic signaling and pathways, and astrocytogenic genes.

Results

The origin of GBM is dependent on dysregulation in multiple genes and pathways that accumulatively converge the cells towards oncogenesis. There are multiple layers of steps in glioblastoma oncogenesis including the failure of cell fate-specific genes to keep the cells differentiated in their specific cell types such as p300, BMP, HOPX, and NRSF/REST. There are genes and signaling pathways that are involved in differentiation and also contribute to GBM such as FGFR3, JAK-STAT, and hey1. The genes that contribute to differentiation processes but also contribute to stemness in GBM include notch, Sox9, Sox4, c-myc gene overrides p300, and then GFAP, leading to upregulation of nestin, SHH, NF-κB, and others. GBM mutations pathologically impact the cell circuitry such as the interaction between Sox2 and JAK-STAT pathway, resulting in GBM development and progression.

Conclusion

Glioblastoma originates when the gene expression of key gliogenic genes and signaling pathways become dysregulated. This study identifies key gliogenic genes having the ability to control oncogenesis in glioblastoma cells, including p300, BMP, PAX6, HOPX, NRSF/REST, LIF, and TGF beta. It also identifies key neurogenic genes having the ability to control oncogenesis including PAX6, neurogenins including Ngn1, NeuroD1, NeuroD4, Numb, NKX6-1 Ebf, Myt1, and ASCL1. This study also postulates how aging contributes to the onset of glioblastoma by dysregulating the gene expression of NF-κB, REST/NRSF, ERK, AKT, EGFR, and others.

Mechanisms of Cell Cycle Arrest and Apoptosis in Glioblastoma

Cells of glioblastoma, the most frequent primary malignant brain tumor, are characterized by their rapid growth and infiltration of adjacent healthy brain parenchyma, which reflects their aggressive biological behavior. In order to maintain their excessive proliferation and invasion, glioblastomas exploit the innate biological capacities of the patients suffering from this tumor. The pathways involved in cell cycle regulation and apoptosis are the mechanisms most commonly affected. The following work reviews the regulatory pathways of cell growth in general as well as the dysregulated cell cycle and apoptosis relevant mechanisms observed in glioblastomas. We then describe the molecular targeting of the current established adjuvant therapy and present ongoing trials or completed studies on specific promising therapeutic agents that induce cell cycle arrest and apoptosis of glioblastoma cells.

Melanoma in patients with Li-Fraumeni syndrome (Review)

Li-Fraumeni syndrome (LFS) is a cancer-prone, autosomal dominant syndrome caused by underlying germline gene mutations of TP53, a tumor-suppressor gene encoding the p53 protein with a major role in apoptosis, DNA repair and cell cycle regulation. Cumulative cancer incidence for LFS patients by the age of 70 years is 80-100%, mostly involving adrenocortical carcinoma, brain tumors, bone and soft tissue sarcomas, leukemia and female breast cancer from the age of 20 years. Dominant negative TP53 variant is correlated with an increased tumorigenesis risk in LFS. Sporadic TP53 mutations are related to almost half of global cancers since p53 in addition to p73 protein represent essential players in anticancer cellular protection. Epidemiological aspects concerning skin cancers, especially malignant melanoma (MM), in LFS are less clear. A low level of statistical evidence demonstrates LFS cases with pediatric MM, multiple MM, spitzoid MM, atypical presentations, mucosal and uveal MM. Retrospective cohorts indicate a higher cumulative risk than the general population by the age of 70 years for MM and basal cell carcinoma. Non-syndromic and syndromic TP53 mutations are a major pathway of metastasis, including MM. In LHS, an important level of awareness involves skin cancers despite not being a part of the typical malignancy-containing picture. Additional data are crucially needed. However, at least one dermatologic control is a step in the multidisciplinary panel of surveillance of these patients; but in cases with benign and pre-malign pigmentations, serial dermatoscopy and full body photography are recommended for early melanoma detection in order to improve the prognosis and to reduce the overall malignancy burden.

Upregulation of ERK-EGR1-heparanase axis by HDAC inhibitors provides targets for rational therapeutic intervention in synovial sarcoma

BACKGROUND

Synovial sarcoma (SS) is an aggressive soft tissue tumor with limited therapeutic options in advanced stage. SS18-SSX fusion oncogenes, which are the hallmarks of SS, cause epigenetic rewiring involving histone deacetylases (HDACs). Promising preclinical studies supporting HDAC targeting for SS treatment were not reflected in clinical trials with HDAC inhibitor (HDACi) monotherapies. We investigated pathways implicated in SS cell response to HDACi to identify vulnerabilities exploitable in combination treatments and improve the therapeutic efficacy of HDACi-based regimens.

METHODS

Antiproliferative and proapoptotic effects of the HDACi SAHA and FK228 were examined in SS cell lines in parallel with biochemical and molecular analyses to bring out cytoprotective pathways. Treatments combining HDACi with drugs targeting HDACi-activated prosurvival pathways were tested in functional assays in vitro and in a SS orthotopic xenograft model. Molecular mechanisms underlying synergisms were investigated in SS cells through pharmacological and gene silencing approaches and validated by qRT-PCR and Western blotting.

RESULTS

SS cell response to HDACi was consistently characterized by activation of a cytoprotective and auto-sustaining axis involving ERKs, EGR1, and the β-endoglycosidase heparanase, a well recognized pleiotropic player in tumorigenesis and disease progression. HDAC inhibition was shown to upregulate heparanase by inducing expression of the positive regulator EGR1 and by hampering negative regulation by p53 through its acetylation. Interception of HDACi-induced ERK-EGR1-heparanase pathway by cell co-treatment with a MEK inhibitor (trametinib) or a heparanase inhibitor (SST0001/roneparstat) enhanced antiproliferative and pro-apoptotic effects. HDAC and heparanase inhibitors had opposite effects on histone acetylation and nuclear heparanase levels. The combination of SAHA with SST0001 prevented the upregulation of ERK-EGR1-heparanase induced by the HDACi and promoted caspase-dependent cell death. In vivo, the combined treatment with SAHA and SST0001 potentiated the antitumor efficacy against the CME-1 orthotopic SS model as compared to single agent administration.

CONCLUSIONS

The present study provides preclinical rationale and mechanistic insights into drug combinatory strategies based on the use of ERK pathway and heparanase inhibitors to improve the efficacy of HDACi-based antitumor therapies in SS. The involvement of classes of agents already clinically available, or under clinical evaluation, indicates the transferability potential of the proposed approaches.

Role of JNK and p53 in Implementation of Functions of Various Types of Regeneration-Competent Cells of the Nervous Tissue

We studied the participation of JNK and p53 in the realization of the growth potential of different types of progenitors of the subventricular zone of mouse brain and secretion of neurotrophins by glial cells. The stimulating role of these signaling molecules in mitotic activity and specialization of multipotent neural stem cells was shown. It was found that JNK and p53 do not participate in the regulation of committed neuronal progenitor cells (clonogenic PSA-NCAM⁺ cells). A dependence of neurotrophic growth factors in individual populations of neuroglia on activity of these protein kinase and transcription factor was revealed. The role of JNK and p53 in astrocytes consists in stimulation of their secretion, and in microglial cells, on the contrary, in its inhibition. The secretory neurotrophic function of oligodendrogliocytes is not associated with JNK and p53 activity.