P53 Tumor Suppressor Research Articles

A novel ITGB8 transcript variant sustains ovarian cancer cell survival through genomic instability and altered ploidy on a mutant p53 background

BackgroundTranscript variants and protein isoforms are central to unique tissue functions and maintenance of homeostasis, in addition to being associated with aberrant states such as cancer, where their crosstalk with the mutated tumor suppressor p53 may contribute to genomic instability and chromosomal rearrangements. We previously identified several novel splice variants in ovarian cancer RNA-sequencing datasets; herein, we aimed to elucidate the biological effects of the Integrin Subunit Beta 8 variant (termed pITGB8-205).MethodsResolution of the full-length sequence of pITGB8-205 through rapid amplification of cDNA ends (RACE-PCR). Cell cycle analysis and karyotype studies were performed to further explore genomic instability. RNA-seq and proteomics analyses were used to identify the differential expression of the genes.ResultsThis full-length study revealed a unique 5’ sequence in pITGB8-205 that differed from the reported ITGB8-205 sequence, suggesting differential regulation of this novel transcript. Under a p53 mutant background, overexpression of pITGB8-205 triggered genetic instability reminiscent of oncogene-induced replicative stress with extensive abnormal mitoses and chromosomal and nuclear aberrations indicative of chromosomal instability, leading to near whole-genome duplication that imposes energy stress on cellular resources. Micronuclei and aneuploidy are striking features of pITGB8-205-overexpressing p53-mutant cells but are not enhanced in p53 wild-type (WT) cells. RNA-seq and proteomics analyses further suggested that p53 inactivation in ovarian cancer provides a permissive intracellular molecular niche for pITGB8-205 to mediate its effects on genomic instability. This observation is pivotal considering that most high-grade serous ovarian carcinoma (HGSC) tumors express mutant p53. The resulting aneuploid clones with enhanced self-renewal and survival capabilities disrupt clonal dominance under stress yet maintain a balance between replicative stress and prosurvival advantages.ConclusionpITGB8-205-overexpressing clones sustain ovarian tumor cell survival, achieve homeostasis and are formidable opponents of therapy.

Molecular Pathogenesis of Human Papillomavirus: Insights into Viral Oncoproteins and Host Integration

Human Papillomavirus (HPV) is a major cause of death from cervical cancer and other anogenital cancers throughout the world. Pathogenicity of HPV is governed by intricate interplay of HPV and host cells mediated primarily by its oncoproteins E6 and E7. These oncoproteins disrupt critical pathways, including those involving tumor suppressors p53 and retinoblastoma (Rb) to induce unregulated cell proliferation and evasion of apoptosis. These mechanisms have been studied in order to develop the different diagnostic tools, such as HPV DNA testing and genotyping, and there are emerging techniques based on E6/E7 mRNA detection and high throughput sequencing. In addition, therapeutic strategies have advanced with the vaccines showing ability to prevent high risk HPV infection and ongoing research to developing targeted therapies to disrupt viral oncoprotein function. New diagnostic and therapeutic approaches to HPV research encompassing an expanding clinical landscape hold promise to reduce incidence of HPV associated malignancies and improve patient outcomes. This review summarizes the molecular pathogenesis of HPV with respect to host cells and discusses its implications for diagnostics and therapeutics, including the need for further development in this area.

Excessive MYC-topoisome activity triggers acute DNA damage, MYC degradation, and replacement by a p53-topoisome

Hyperproliferation driven by the protooncogene MYC may lead to tumor suppressor p53 activating DNA damage that has been presumed to derive from hypertranscription and over-replication. Here, we report that excessive MYC-topoisome (MYC/topoisomerase 1/topoisomerase 2) activity acutely damages DNA-activating pATM and p53. In turn, MYC is shut off and degraded, releasing TOP1 and TOP2A from MYC topoisomes invitro and invivo. To manage the topological and torsional stress generated at its target genes, p53 assembles a separate topoisome. Because topoisomerase activity is intrinsically DNA damaging, p53 topoisomes provoke an initial burst of DNA damage. Because p53, unlike MYC, upregulates the DNA-damage response (DDR) and activates tyrosyl-DNA-phosphodiesterase (TDP) 1 and TDP2, it suppresses further topoisome-mediated damage. The physical coupling and activation of TOP1 and TOP2 by p53 creates a tool that supports p53-target expression while braking MYC-driven proliferation in mammalian cells.

Unraveling the mechanisms of glioblastoma's resistance: investigating the influence of tumor suppressor p53 and non-coding RNAs.

Glioblastoma (GB) is one of the most fatal CNS malignancies, and its high resistance to therapy and poor outcomes have made it one of the primary challenges in oncology. Resistance to standard therapy, i.e., radio-chemotherapy with temozolomide, is one of the principal causes of the poor prognostic outcomes of GB. Finding the molecular basis of GB resistance to therapy is key to creating effective solution approaches. The general problem of GB resistance is supervised by cancer suppressive protein, p53, and has become a very special interest in molecular research in recent decades. The principal aim of this manuscript is to perform a comprehensive survey on the complex network of interactions developed by p53 with non-coding RNAs (ncRNA) in the context of GB resistance. The present article details the functional aspects of p53 as a cellular stress response protein, including its roles in apoptosis, cell cycle regulation, and DNA repair in glioblastoma (GB), along with the disruption of p53 and its involvement in chemoresistance (CR). It also highlights several classes of ncRNAs, namely microRNAs, long ncRNAs, and circular RNAs, that manipulate p53 signaling in GB-CR. The article likewise explains how disruption in the expression of these ncRNAs can promote GB-CR and how it interacts with essential cellular functions, such as proliferation, apoptosis, and DNA repair. The manuscript also describes the potential of targeting p53 and ncRNAs with their diagnostic and prognostic potential as novel promising therapeutics for GB. Nevertheless, ncRNA-based biomarkers still present challenges for their suitability in GB resistance. However, modern research continues to discover novel prediction targets, potentially enhancing patient outcomes and therapeutic options. Therefore, the neutralization of this intricate regulatory network of GB resistance might have a primary clinical effect in fighting GB resistance therapy and thus might lead to a substantial increase in patient survival and quality of life.

Modulation of p300 acetylation to protect against doxorubicin-induced cardiotoxicity

Abstract Background Doxorubicin (DOX) is a widely-used anti-neoplastic agent, but the most common adverse reaction to its use is cardiotoxicity(1). DOX acts by producing reactive oxygen species (ROSs) that cause DNA damage(1,2), which activates various proteins, including the tumour suppressor p53 and the acetyltransferase p300. When activated, p300 acetylates and increases the activity of p53 which leads to increased apoptotic activity(3). Cardiotoxicity results because the heart has limited mechanisms to dispose of ROSs(4), and because cardiomyocytes have a low turnover rate(5). Purpose We examined the p300 inhibitor Theracurmin (THR)(6,7) as a candidate to prevent DOX cardiotoxicity using an in-vivo mouse model, and sought to elucidate the underlying molecular mechanisms using in-vitro studies. Methods C57BL/6 mice were pre-treated with THR or vehicle (as control), then administered DOX or vehicle. Cardiac function was evaluated by echocardiography and cardiac catheterization. In vitro studies used cardiac fibroblasts (FBs) and cardiac endothelial cells (ECs) pre-treated with THR, then with DOX, as in the animal studies. Western blotting and rt-qPCR was used to quantify protein and mRNA levels of genes in the p53-p300 pathway or related to apoptosis, oxidative stress, and cell cycle control. Results DOX-treated mice showed significant decreases in left ventricular (LV) ejection fraction (LVEF, p=0.0004), fractional shortening (FS, p=0.0012), and a significant increase in end-systolic volume (ESV, p=0.0004). We also showed a significant decrease in anterior (LVAW;d, p=0.005) and posterior (LVPW;d, p=0.005) wall thickness of the LV in these mice. However, when mice were pre-treated with THR prior to DOX administration, we saw significant increases in LVEF (p=0.045) and LVPW;d (p=0.015), and a significant decrease in ESV (p=0.0047) compared to those that were not pre-treated. In-vitro analyses demonstrated a significant increase in cleaved caspase 3 protein expression in DOX-treated ECs (p=0.007), that was not prevented by THR pre-treatment. In DOX-treated FBs, we saw a reduction in AKT mRNA (p=0.017) and increases in BAX 9p=0.008), P21 (p=0.0001), and GADD45 (0.037) mRNA expression. In DOX-treated ECs, we also saw significant increases in BAX (p=0.015) and P21 (p=0.011) mRNA expression. These changes in mRNA expression were not reversed with THR pre-treatment in either cell type. Conclusion THR pre-treatment successfully mitigated functional deficits and structural deficits associated with DOX cardiotoxicity. In-vitro studies show that THR pre-treatment was not sufficient to significantly prevent changes in key molecular targets associated with apoptosis. Further studies are required to elucidate the mechanism behind the observed functional changes.Abstract OverviewAbstract Results

Effect of infection by Mycoplasma arginini and Mycoplasma salivarium on the oncogenic properties of lung cancer cell line A549

Most mycoplasma species are the extracellular parasites affecting different cellular processes including proliferation, cell cycle, protein synthesis, DNA repair and others. Mycoplasma infection was shown to contribute to the pathology of various diseases, including cancer. Upon infection, mycoplasmas typically activate the tumor-associated NF-kB pathway, which is associated with EMT, the main mechanism of metastasis.In this study, we found that two different mycoplasma strains, M. arginini and M. salivarium, promoted the initiation of EMT and simultaneous suppression of the p53 tumor suppressor in A549 lung cancer cells. This led to an increase of cancer cell motility, resistance to the antitumor drug etoposide concomitantly with decreased autophagy. These data indicate that mycoplasmas are able to increase the tumorigenic potential of cancer host cells.

Novel bioassays based on 3D-printed device for sensing of hypoxia and p53 pathway in 3D cell models.

Cell-based assays are widely exploited for drug screening and biosensing, providing useful information about bioactivity of target analytes and complex biological samples. It is well recognized that 3D cell models are required to achieve highly valuable information, also from the perspective of replacing animal models. However, bioassays relying on 3D cell models are generally highly demanding in terms of facilities, equipment, and skilled personnel requirements. To reduce cost, increase sustainability, and provide a flexible 3D cell-based platform for bioassays, we here report a novel approach based on a 3D-printed microtissue device. To assess the suitability of this strategy for reporter gene technology, we selected to monitor two molecular pathways which were of interest in several applications, hypoxia signaling and the p53 pathway. The investigation of such pathways is highly relevant in fields spanning from drug screening to bioactivity monitoring for industrial by-product valorization. Microtissues of human hepatocarcinoma (HepG2) and human embryonic kidney (Hek293T) cell lines were obtained with a low-cost and sustainable chip platform and bioassays were developed to monitor the hypoxia-inducible factors (HIFs) and the p53 tumor suppressor pathway. HepG2 and Hek293T 3D cell models were genetically engineered to express the Luc2P from Photinus pyralis firefly either under the regulation of p53 or HIF response elements. The bioassays allowed quantitative assessment of hypoxia and tumoral activity with 1,10-phenanthroline for HIF and with doxorubicin for p53 pathway activation, respectively, showing good potential for applications of this sustainable and low-cost 3D-printed microfluidic platform for bioactivity analyses, drug screening, and precision medicine.

Tryptophanol-derived oxazoloisoindolinone fluorescent probes for cellular localization studies of p53 activators

The protein p53 is a transcription factor with several key roles in cells, including acting as a tumour suppressor. In most human cancers its tumour suppressor function is inactivated, either through inhibition by negative regulators or by mutation in the TP53 gene. Thus, there is a high interest in developing molecules able to activate p53 tumour suppressor activity. Tryptophanol-derived isoindolinones are known to act as wild-type and mutant p53 activators. Specifically, SLMP53-1 is a non-fluorescent wild-type and mutant p53 R280K reactivator, with potent in vivo anti-tumour activity in HCT116 and MDA-MB-231 mice xenograft models. With the aim of studying tryptophanol-derived isoindolinones intracellular localization by fluorescence microscopy, three SLMP53-1 based fluorescent probes were prepared. Here we report the design, synthesis, photophysical characterization, antiproliferative activity and cell localization studies of these fluorescent probes.The previously described structure–activity relationships of the SLMP53-1 scaffold set the basis for the design the fluorescent probes. The probes were prepared by connecting a small fluorophore (dansyl or 7-nitrobenzofurazan) to the indole nitrogen of the tryptophanol-derived oxazoloisoindolinone SLMP53-1 through two different linkers. The antiproliferative activity and cell localization studies of the three fluorescent probes were performed in HCT116 cells. The three probes showed enhanced internalization when compared with their fluorophore-linker intermediates, good photo-stability and high affinity for the endoplasmic reticulum, indicating the potential involvement of endoplasmic reticulum in the mechanism of action of tryptophanol-derived oxazoloisoindolinones.

Inulin-based nanoparticles for targeted siRNA delivery in acute kidney injury

RNA interference has emerged as a promising therapeutic strategy to tackle acute kidney injury (AKI). Development of targeted delivery systems is highly desired for selective renal delivery of RNA and improved therapeutic outcomes in AKI. Inulin is a plant polysaccharide traditionally employed to measure glomerular filtration rate. Here, we describe the synthesis of inulin modified with α-cyclam-p-toluic acid (CPTA) to form a novel renal-targeted polymer, Inulin-CPTA (IC), which is capable of selective siRNA delivery to the injured kidneys. We show that conjugating CPTA to inulin imparts IC with targeting properties for cells that overexpress the C-X-C chemokine receptor 4 (CXCR4). Self-assembled IC/siRNA nanoparticles (polyplexes) demonstrated rapid accumulation in the injured kidneys with selective uptake and prolonged retention in injured renal tubules overexpressing the CXCR4 receptor. Tumor-suppressor protein p53 contributes significantly to the pathogenesis of AKI. siRNA-induced silencing of p53 has shown therapeutic potential in several preclinical studies, making it an important target in the treatment of AKI. Systemically administered nanoparticles formulated using IC and siRNA against p53 selectively accumulated in the injured kidneys and potently silenced p53 expression. Selective p53 knockdown led to positive therapeutic outcomes in mice with cisplatin-induced AKI, as seen by reduced tubular cell death, renal injury, inflammation, and overall improved renal function. These findings indicate that IC is a promising new carrier for renal-targeted delivery of RNA for the treatment of AKI.

Centrioles are frequently amplified in early B cell development but dispensable for humoral immunity

Centrioles define centrosome structure and function. Deregulation of centriole numbers can cause developmental defects and cancer. The p53 tumor suppressor limits the growth of cells lacking or harboring additional centrosomes and can be engaged by the “mitotic surveillance” or the “PIDDosome pathway”, respectively. Here, we show that early B cell progenitors frequently present extra centrioles, ensuing their high proliferative activity and related DNA damage. Extra centrioles are efficiently cleared during B cell maturation. In contrast, centriole loss upon Polo-like kinase 4 (Plk4) deletion causes apoptosis and arrests B cell development. This defect can be rescued by co-deletion of Usp28, a critical component of the mitotic surveillance pathway, that restores cell survival and maturation. Centriole-deficient mature B cells are proliferation competent and mount a humoral immune response. Our findings imply that progenitor B cells are intolerant to centriole loss but permissive to centriole amplification, a feature potentially facilitating their malignant transformation.

The role of p53 in male infertility.

The tumor suppressor p53 is a transcription factor involved in a variety of crucial cellular functions, including cell cycle arrest, DNA repair and apoptosis. Still, a growing number of studies indicate that p53 plays multiple roles in spermatogenesis, as well as in the occurrence and development of male infertility. The representative functions of p53 in spermatogenesis include the proliferation of spermatogonial stem cells (SSCs), spermatogonial differentiation, spontaneous apoptosis, and DNA damage repair. p53 is involved in various male infertility-related diseases. Innovative therapeutic strategies targeting p53 have emerged in recent years. This review focuses on the role of p53 in spermatogenesis and male infertility and analyses the possible underlying mechanism involved. All these conclusions may provide a new perspective on drug intervention targeting p53 for male infertility treatment.

Discovery and Characterization of Brigimadlin, a Novel and Highly Potent MDM2-p53 Antagonist Suitable for Intermittent Dose Schedules.

p53 is known as the guardian of the genome and is one of the most important tumor-suppressors. It is inactivated in most tumors, either via tumor protein p53 (TP53) gene mutation or copy number amplification of key negative regulators, e.g., mouse double minute 2 (MDM2). Compounds that bind to the MDM2 protein and disrupt its interaction with p53 restore p53 tumor suppressor activity, thereby promoting cell cycle arrest and apoptosis. Previous clinical experience with MDM2-p53 protein-protein interaction antagonists (MDM2-p53 antagonists) have demonstrated that thrombocytopenia and neutropenia represent on-target dose-limiting toxicities that might restrict their therapeutic utility. Dosing less frequently, while maintaining efficacious exposure, represents an approach to mitigate toxicity and improve the therapeutic window of MDM2-p53 antagonists. However, to achieve this, a molecule possessing excellent potency and ideal pharmacokinetic properties is required. Here, we present the discovery and characterization of brigimadlin (BI 907828), a novel, investigational spiro-oxindole MDM2-p53 antagonist. Brigimadlin exhibited high bioavailability and exposure, as well as dose-linear pharmacokinetics in preclinical models. Brigimadlin treatment restored p53 activity and led to apoptosis induction in preclinical models of TP53 wild-type, MDM2-amplified cancer. Oral administration of brigimadlin in an intermittent dosing schedule induced potent tumor growth inhibition in several TP53 wild-type, MDM2-amplified xenograft models. Exploratory clinical pharmacokinetic studies (NCT03449381) showed high systemic exposure and a long plasma elimination half-life in cancer patients who received oral brigimadlin. These findings support the continued clinical evaluation of brigimadlin in patients with MDM2-amplified cancers, such as dedifferentiated liposarcoma.

Pan-cancer analysis of TP53 mutations and their association with liver cancer and aristolochic acids

Liver cancer is a major global health concern, as its incidence continues to rise in numerous countries, making it a leading cause of cancer-related deaths. The TP53 gene, which encodes the p53 tumor suppressor protein, plays a crucial role in regulating cell growth and division. Mutations in TP53 have been implicated in increased risk for liver cancer development. In this study, we aim to conduct a pan-cancer analysis to further investigate the potential role of TP53 mutations in various cancer types and their relationship with liver cancer. Additionally, we will explore the interplay between TP53 gene mutations, liver cancer, and exposure to Aristolochic acids (AAs). To achieve these goals, we will utilize data from The Cancer Genome Atlas (TCGA) project and the Gene Expression Omnibus (GEO) databases, enabling a comprehensive analysis of TP53 in the context of multiple cancer types.

Cucurbitacin-E; Curvularia lunata Secondary Metabolite as a BRCA 1 and 2 Regulator in Mice Associated Breast Cancer

Background: Cucurbitacin-induced apoptosis and inhibition of cell growth can render several cancers ineffective. The microbial transformation of cucurbitacin-E-glucoside to cucurbitacin- E was carried out by Curvularia lunata (NRRL 2178). Moreover, in vitro anticancer activity against the MCF-7 cell line as well as in vivo anticancer activity against dimethylbenz (a) anthracene (DMBA)-induced breast cancer in mice using cucurbitacin-E was evaluated. Methods: The cucurbitacin-E-glucoside was biotransformed by Curvularia lunata to cucurbitacin- E, and the isolated compound was tested in vitro against the MCF-7 cell line, and its IC50 was calculated. LD50 of cucurbitacin-E was estimated in mice, and its protective activity against DMBA-induced cancer in mice was studied. Breast cancer induction was done by a single-dose subcutaneous administration of DMBA (50 mg). Plasma ALT, AST, ALP, and LDH, as well as GSH, SOD, GPx, MDA, TNF-α, IL-6, and tumor suppressor P53 assays, were used to assess cucurbitacin- E's capacity to protect the liver and breast against DMBA-induced toxicity. Moreover, by assessing the gene expression of tumor suppressor genes (BRCA 1 and 2) and conducting histopathological analysis, the suppressive effect of cucurbitacin-E was examined. Results: The IC50 value of cucurbitacin-E against MCF-7 cell lines equals 72.15 ± 0.64 μg/ml. LD50 of cucurbitacin-E given orally in adult mice is equal to 1200 mg/kg b.w. The levels of plasma ALT, AST, ALP, and LDH were decreased significantly in DMBA-treated mice when administered with cucurbitacin-E at 1/50 LD50 (24 mg/kg/b.w.) and 1/20 LD50 (60 mg/kg/b.w.). In breast tissue, the levels of GSH, SOD, GPx, and P53 were significantly increased, as were decreased levels of TNF-α, IL-6, P53, and MDA. Conversely, there was a downregulation in the mRNA expression levels of BRCA1 and BRCA2. The histopathological analysis revealed that cucurbitacin-E management improved the tissue architecture of breast tumors. Conclusions: These findings demonstrate the ability of cucurbitacin-E to inhibit cancer cells in the rat breast by controlling oxidative stress and inflammatory biomarkers, as well as downregulating the mRNA expression levels of BRCA1 and BRCA2.

A structure-based virtual screening identifies a novel MDM2 antagonist in the activation of the p53 signaling and inhibition of tumor growth.

p53, a tumor suppressor protein, has a vital role in the regulation of the cell cycle, apoptosis, and DNA damage repair. The degradation of p53 is predominantly controlled by the murine double minute 2 (MDM2) protein, a ubiquitin E3 ligase. The overexpression or amplification of MDM2 is commonly observed in various human cancers bearing wild-type p53 alleles, leading to the rapid degradation of the p53 protein and the attenuation of p53 tumor suppression functions. Thus, a major effort in p53-based cancer therapy has been to research MDM2 antagonists that specifically stabilize and activate p53, leading to the suppression of tumor growth. However, despite numerous efforts to develop MDM2 antagonists, to date they have failed to reach clinical use, largely because of the cytotoxicity associated with these small molecules. This study used our newly designed structure-based virtual screening approach on a commercial compound library to identify a novel compound, CGMA-Q18, which directly binds to MDM2, leading to the activation of p53, the induction of apoptosis, and cell cycle arrest in cancer cells. Notably, CGMA-Q18 significantly inhibited tumor xenograft growth in nude mice without observable toxicity. These findings highlight our useful virtual screening protocol and CGMA-Q18 as a putative MDM2 antagonist.

Modulation of Tumor Suppressor Genes by Histone Deacetylase Inhibitors in Cancer Therapy

Histone deacetylase (HDAC) inhibitors have emerged as promising therapeutics for various cancers due to their ability to modulate gene expression profiles and restore normal cellular functions. Among the key targets of HDAC inhibitors are tumor suppressor genes, which play crucial roles in regulating cell cycle progression, apoptosis, and DNA repair. However, despite their therapeutic potential, HDAC inhibitors come with significant drawbacks. These include off-target effects that can lead to unintended alterations in gene expression, toxicity to normal cells, and the development of drug resistance in some cancer patients. Additionally, the non-specific nature of some HDAC inhibitors can result in side effects such as fatigue, gastrointestinal disturbances, and hematological toxicity, limiting their clinical utility. This review provides a comprehensive overview of the impact of HDAC inhibitors on tumor suppressor genes in cancer therapy. We discussed the mechanisms by which HDAC inhibitors regulate the expression of tumor suppressor genes, including p53, p21, BRCA1, PTEN, and others, through histone hyperacetylation and chromatin remodeling. Furthermore, we described the therapeutic implications of HDAC inhibitor-induced modulation of tumor suppressor genes in various cancer types, highlighting the potential for combination therapies and personalized treatment approaches. Understanding the interplay between HDAC inhibitors and tumor suppressor genes is critical for optimizing the efficacy of HDAC inhibitor-based therapies and advancing precision medicine in oncology.

MAD1 upregulation sensitizes to inflammation-mediated tumor formation.

Mitotic Arrest Deficient 1 (gene name MAD1L1), an essential component of the mitotic spindle assembly checkpoint, is frequently overexpressed in colon cancer, which correlates with poor disease-free survival. MAD1 upregulation induces two phenotypes associated with tumor promotion in tissue culture cells-low rates of chromosomal instability (CIN) and destabilization of the tumor suppressor p53. Using CRISPR/Cas9 gene editing, we generated a novel mouse model by inserting a doxycycline (dox)-inducible promoter and HA tag into the endogenous mouse Mad1l1 gene, enabling inducible expression of HA-MAD1 following exposure to dox in the presence of the reverse tet transactivator (rtTA). A modest 2-fold overexpression of MAD1 in murine colon resulted in decreased p53 expression and increased mitotic defects consistent with CIN. After exposure to the colon-specific inflammatory agent dextran sulfate sodium (DSS), 31% of mice developed colon lesions, including a mucinous adenocarcinoma, while none formed in control animals. Lesion incidence was particularly high in male mice, 57% of which developed at least one hyperplastic polyp, adenoma or adenocarcinoma in the colon. Notably, mice expressing HA-MAD1 also developed lesions in tissues in which DSS is not expected to induce inflammation. These findings demonstrate that MAD1 upregulation is sufficient to promote colon tumorigenesis in the context of inflammation in immune-competent mice.

Predicting p53-dependent cell transitions from thermodynamic models.

A cell's fate involves transitions among its various states, each defined by a distinct gene expression profile governed by the topology of gene regulatory networks, which are affected by 3D genome organization. Here, we develop thermodynamic models to determine the fate of a malignant cell as governed by the tumor suppressor p53 signaling network, taking into account long-range chromatin interactions in the mean-field approximation. The tumor suppressor p53 responds to stress by selectively triggering one of the potential transcription programs that influence many layers of cell signaling. These range from p53 phosphorylation to modulation of its DNA binding affinity, phase separation phenomena, and internal connectivity among cell fate genes. We use the minimum free energy of the system as a fundamental property of biological networks that influences the connection between the gene network topology and the state of the cell. We constructed models based on network topology and equilibrium thermodynamics. Our modeling shows that the binding of phosphorylated p53 to promoters of target genes can have properties of a first order phase transition. We apply our model to cancer cell lines ranging from breast cancer (MCF-7), colon cancer (HCT116), and leukemia (K562), with each one characterized by a specific network topology that determines the cell fate. Our results clarify the biological relevance of these mechanisms and suggest that they represent flexible network designs for switching between developmental decisions.

Redox Status and Protein Glutathionylation in Binase-Treated HPV16-Positive SiHa Carcinoma Cells

Human papillomavirus type 16 (HPV16) belongs to viruses of the high-risk type and is associated by overexpression of E6 and E7 oncoproteins, which determine the oncogenic properties of the virus, such as immortalization and malignant transformation of proliferating epithelial cells. The biogenesis of redox-sensitive proteins E6 and E7 at the early stages of viral infection leads to blocking of the cell antioxidant defense system and ubiquintin-dependent degradation of p53 and Rb tumor suppressors. Maintaining high rates of tumor cell proliferation contributes to an increase in the level of reactive oxygen species (ROS) and a shift in the redox balance towards oxidative processes. Reduced glutathione (GSH) provides antioxidant protection to tumor cells through S-glutathionylation of thiol groups of redox-sensitive proteins, which leads to the appearance of multidrug-resistant forms of cancer. In this regard, drugs restoring redox balance and increasing susceptibility to antitumor therapy are of particular importance. We have established that, Bacillus pumilus RNase (binase) modulates the redox-dependent regulatory mechanisms that ensure tumor cell resistance to apoptosis in HPV-16-positive SiHa cells of cervical squamous cell carcinoma,. Binase in nontoxic concentrations initiates a number of pre-apoptogenic changes, i.e., decreases ROS and reduced glutathione (GSH) levels, suppresses the expression of the E6 oncoprotein, activates the expression of the p53 tumor suppressor, and reduces the mitochondrial potential of tumor cells. Binase-induced disruption of the integrity of the mitochondrial membrane is a signal for activation of the mitochondrial apoptosis pathway.

Assessment <b></b>of Serum P53 Protein Level in Adult Patients with Acute Myeloid Leukemia in Correlation with Response to Treatment

Background: Acute myeloid leukemia (AML) is an adult leukemia characterized by rapid proliferation of undifferentiated myeloid precursors, leading to bone marrow (BM) failure and impaired erythropoiesis. The p53 tumor suppressor protein regulates cell division and inhibits tumor development by preventing cell proliferation of altered or damaged DNA. It orchestrates various cellular reactions, including cell cycle arrest, DNA repair, and antioxidant properties. Objectives: To investigate the relationship of P53 serum level with hematological findings, remission, and survival status in de novo AML patients. Methods: This is a cross-sectional study that enrolled 63 newly diagnosed de novo AML patients, and 15 sex- and age-matched healthy persons as a control group. Serum P53 levels were assessed using the enzyme-linked immunosorbent assay (ELISA) technique before initiating induction chemotherapy. The study was performed between November 2022 and May 2023 at the Hematology and Bone Marrow Transplant Center of the Medical City Complex in Baghdad. Results: There were significantly lower P53 serum levels in AML patients before starting chemotherapy compared to the control group. However, no substantial difference in P53 levels was identified between AML patients achieving complete remission and those exhibiting no response, nor between alive and deceased individuals. Furthermore, there was a positive yet statistically non-significant correlation between serum P53 levels and age, and no significant relationship between P53 levels and sex or various hematological parameters. Conclusion: P53 levels are low in AML patients. They are not associated with remission status or survival after six months and are not correlated with hematological values.