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The prevention of tumor recurrence by the successful targeting of glioma stem cells endowed with a tumor-initiating capacity is deemed the key to the long-term survival of glioblastoma patients. Glioma stem cells are characterized by their marked therapeutic resistance; however, recent evidence suggests that they have unique vulnerabilities that may be therapeutically targeted. We investigated MDM2 expression levels in glioma stem cells and their non-stem cell counterparts and the effects of the genetic and pharmacological inhibition of MDM2 on the viability of these cells as well as downstream molecular pathways. The results obtained showed that MDM2 expression was substantially higher in glioma stem cells than in their non-stem cell counterparts and also that the inhibition of MDM2, either genetically or pharmacologically, induced a more pronounced activation of the p53 pathway and apoptotic cell death in the former than in the latter. Specifically, the inhibition of MDM2 caused a p53-dependent increase in the expression of BAX and PUMA and a decrease in the expression of survivin, both of which significantly contributed to the apoptotic death of glioma stem cells. The present study identified the MDM2–p53 axis as a novel therapeutic vulnerability, or an Achilles' heel, which is unique to glioma stem cells. Our results, which suggest that non-stem, bulk tumor cells are less sensitive to MDM2 inhibitors, may help guide the selection of glioblastoma patients suitable for MDM2 inhibitor therapy. [ABSTRACT FROM AUTHOR]

The tumor suppressor protein p53 is central to cancer biology, with its pathway reactivation emerging as a promising therapeutic strategy in oncology. This study introduced LZ22, a novel compound that selectively inhibits the growth, migration, and metastasis of tumor cells expressing wild-type p53, demonstrating ineffectiveness in cells devoid of p53 or those expressing mutant p53. LZ22's mechanism of action involves a high-affinity interaction with the histidine-96 pocket of the MDM2 protein. This interaction disrupted the MDM2-p53 binding, consequently stabilizing p53 by shielding it from proteasomal degradation. LZ22 impeded cell cycle progression and diminished cell proliferation by reinstating the p53-dependent suppression of the CDK2/Rb signaling pathway. Moreover, LZ22 alleviated the p53-dependent repression of Snail transcription factor expression and its consequent EMT, effectively reducing tumor cell migration and distal metastasis. Importantly, LZ22 administration in tumor-bearing mice did not manifest notable side effects. The findings position LZ22 as a structurally unique reactivator of p53, offering therapeutic promise for the management of human cancers with wild-type TP53. [ABSTRACT FROM AUTHOR]

Abstract Purpose The present study aimed to explore the anticancer activity of hirsuteine (HST), an indole alkaloid from the traditional Chinese herbal medicine Uncaria rhynchophylla, against colorectal cancer (CRC) and the underlining mechanism. Methods MTT, colony formation, flow cytometry and MDC staining were conducted to confirm the antiproliferative effect of HST on human CRC cells harboring different p53 status. Protein expressions were evaluated by the Western blot analysis. p53 protein half-life and the interaction between p53 and MDM2 were investigated using cycloheximide (CHX)-chase assay and Co-immunoprecipitation (Co-IP), respectively. Transcriptional activity of p53 was examined by qRT-PCR and Chromatin immunoprecipitation (ChIP). Xenograft tumor in nude mice was created to evaluate in vivo anticancer effect of HST against CRC. Results HST inhibited cell growth, arrested cell cycle and induced autophagy, showing efficient anticancer effects on CRC cells independent of p53 status. In HCT-8 cells, HST prolonged wtp53 half-life, and upregulated mRNA level of p21, suggesting that HST activated the p53 pathway through enhancement of wtp53 stability and transcriptional activity. Meanwhile in SW620 cells, HST induced MDM2-mediated proteasomal degradation of mutp53R273H, increased the DNA-binding ability of mutp53R273H at the p21 promoter, and upregulated mRNA levels of p21 and MDM2, demonstrating the depletion of mutp53R273H and restoration of its wild-type-like properties by HST. p53 knockdown by siRNA significantly impaired the growth inhibition of HST on HCT-8 and SW620 cells. Moreover, HST showed anticancer effects in xenograft tumors, accompanied with an opposite regulation of wtp53 and mutp53 R273H in mechanism. Conclusion This study revealed the anticancer efficacy of HST against CRC via opposite modulation of wtp53 and mutp53 R273H, indicating the potential of HST to be a CRC drug candidate targeting p53 signaling.

The frequency of p53 mutations in colorectal cancer (CRC) is approximately 40–50%. A variety of therapies are being developed to target tumors expressing mutant p53. However, potential therapeutic targets for CRC expressing wild‐type p53 are rare. In this study, we show that METTL14 is transcriptionally activated by wild‐type p53 and suppresses tumor growth only in p53‐wild‐type (p53‐WT) CRC cells. METTL14 deletion promotes both AOM/DSS and AOM‐induced CRC growth in mouse models with the intestinal epithelial cell‐specific knockout of METTL14. Additionally, METTL14 restrains aerobic glycolysis in p53‐WT CRC, by repressing SLC2A3 and PGAM1 expression via selectively promoting m6A‐YTHDF2‐dependent pri‐miR‐6769b/pri‐miR‐499a processing. Biosynthetic mature miR‐6769b‐3p and miR‐499a‐3p decrease SLC2A3 and PGAM1 levels, respectively, and suppress malignant phenotypes. Clinically, METTL14 only acts as a beneficial prognosis factor for the overall survival of p53‐WT CRC patients. These results uncover a new mechanism for METTL14 inactivation in tumors and, most importantly, reveal that the activation of METTL14 is a critical mechanism for p53‐dependent cancer growth inhibition, which could be targeted for therapy in p53‐WT CRC. Synopsis: METTL14 specifically counteracts colorectal tumorigenesis in p53‐wild‐type cells by attenuating aerobic glycolysis. METTL14 decreases SLC2A3 and PGAM1 expression via selectively promoting m6A‐YTHDF2‐dependent pri‐miR‐6769b and pri‐miR‐499a processing. METTL14 is transcriptionally activated by wild‐type p53 and inhibits progression of p53‐wild‐type colorectal cancer (CRC).METTL14‐mediated m6A modification promotes YTHDF2‐dependent processing of pri‐miR‐6769b and pri‐miR‐499a.miR‐499a‐3p and miR‐6769b‐3p target SLC2A3 and PGAM1, respectively, thereby inhibiting glycolysis in p53‐wild‐type CRC.METTL14 expression inversely correlates with poor prognosis in p53‐wild‐type colorectal cancer. [ABSTRACT FROM AUTHOR]

The p53 protein has appropriately been named the "guardian of the genome". In almost all human cancers, the powerful tumor suppressor function of p53 is compromised by a variety of mechanisms, including mutations with either loss of function or gain of function and inhibition by its negative regulators MDM2 and/or MDMX. We review herein the progress made on different therapeutic strategies for targeting p53. [ABSTRACT FROM AUTHOR]

The p53 protein is a tumor suppressor encoded by the TP53 gene and consists of 393 amino acids with four main functional domains. This protein responds to various cellular stresses to regulate the expression of target genes, thereby causing DNA repair, cell cycle arrest, apoptosis, metabolic changes, and aging. Mutations in the TP53 gene and the functions of the wild-type p53 protein (wtp53) have been linked to various human cancers. Eight TP53 gene mutations are located in codons, constituting 28% of all p53 mutations. The p53 can be used as a biomarker for tumor progression and an excellent target for designing cancer treatment strategies. In wild-type p53-carrying cancers, abnormal signaling of the p53 pathway usually occurs due to other unusual settings, such as high MDM2 expression. These differences between cancer cell p53 and normal cells have made p53 one of the most important targets for cancer treatment. In this review, we have dealt with various issues, such as the relative contribution of wild-type p53 loss of function, including transactivation-dependent and transactivation-independent activities in oncogenic processes and their role in cancer development. We also discuss the role of p53 in the process of ferroptosis and its targeting in cancer treatment. Finally, we focus on p53-related drug delivery systems and investigate the challenges and solutions.

The transcription factor p53 is the most well-characterized tumor suppressor involved in multiple cellular processes, which has expanded to the regulation of metabolism in recent decades. Accumulating evidence reinforces the link between the disturbance of p53-relevant metabolic activities and tumor development. However, a full-fledged understanding of the metabolic roles of p53 and the underlying detailed molecular mechanisms in human normal and cancer cells remain elusive, and persistent endeavor is required to foster the entry of drugs targeting p53 into clinical use. This mini-review summarizes the indirect regulation of cellular metabolism by wild-type p53 as well as mutant p53, in which mechanisms are categorized into three major groups: through modulating downstream transcriptional targets, protein-protein interaction with other transcription factors, and affecting signaling pathways. Indirect mechanisms expand the p53 regulatory networks of cellular metabolism, making p53 a master regulator of metabolism and a key metabolic sensor. Moreover, we provide a brief overview of recent achievements and potential developments in the therapeutic strategies targeting mutant p53, emphasizing synthetic lethal methods targeting mutant p53 with metabolism. Then, we delineate synthetic lethality targeting mutant p53 with its indirect regulation on metabolism, which expands the synthetic lethal networks of mutant p53 and broadens the horizon of developing novel therapeutic strategies for p53 mutated cancers, providing more opportunities for cancer patients with mutant p53. Finally, the limitations and current research gaps in studies of metabolic networks controlled by p53 and challenges of research on p53-mediated indirect regulation on metabolism are further discussed. [ABSTRACT FROM AUTHOR]

The central role of an aberrantly activated EMT program in defining the critical features of aggressive carcinomas is well documented and includes cell plasticity, metastatic dissemination, drug resistance, and cancer stem cell-like phenotypes. The p53 tumor suppressor is critical for leashing off all the features mentioned above. On the molecular level, the suppression of these effects is exerted by p53 via regulation of its target genes, whose products are involved in cell cycle, apoptosis, autophagy, DNA repair, and interactions with immune cells. Importantly, a set of specific mutations in the TP53 gene (named Gain-of-Function mutations) converts this tumor suppressor into an oncogene. In this review, we attempted to contrast different regulatory roles of wild-type and mutant p53 in the multi-faceted process of EMT.

The transcription factor p53 is the most well-characterized tumor suppressor involved in multiple cellular processes, which has expanded to the regulation of metabolism in recent decades. Accumulating evidence reinforces the link between the disturbance of p53-relevant metabolic activities and tumor development. However, a full-fledged understanding of the metabolic roles of p53 and the underlying detailed molecular mechanisms in human normal and cancer cells remain elusive, and persistent endeavor is required to foster the entry of drugs targeting p53 into clinical use. This mini-review summarizes the indirect regulation of cellular metabolism by wild-type p53 as well as mutant p53, in which mechanisms are categorized into three major groups: through modulating downstream transcriptional targets, protein-protein interaction with other transcription factors, and affecting signaling pathways. Indirect mechanisms expand the p53 regulatory networks of cellular metabolism, making p53 a master regulator of metabolism and a key metabolic sensor. Moreover, we provide a brief overview of recent achievements and potential developments in the therapeutic strategies targeting mutant p53, emphasizing synthetic lethal methods targeting mutant p53 with metabolism. Then, we delineate synthetic lethality targeting mutant p53 with its indirect regulation on metabolism, which expands the synthetic lethal networks of mutant p53 and broadens the horizon of developing novel therapeutic strategies for p53 mutated cancers, providing more opportunities for cancer patients with mutant p53. Finally, the limitations and current research gaps in studies of metabolic networks controlled by p53 and challenges of research on p53-mediated indirect regulation on metabolism are further discussed.

Background: Management of patients with prostate cancer and bone metastatic disease remains a major clinical challenge. Loss or mutation of p53 has been identified to be involved in the tumor progression and metastasis. Nevertheless, direct evidence of a specific role for wild-type p53 (wt-p53) in bone metastasis and the mechanism by which this function is mediated in prostate cancer remain obscure. Methods: The expression and protein levels of wt-53, AIP4, and CXCR4 in prostate cancer cells and clinical specimens were assessed by real-time PCR, immunohistochemistry and western blot analysis. The role of wt-p53 in suppressing aggressive and metastatic tumor phenotypes was assessed using in vitro transwell chemotaxis, wound healing, and competitive colocalization assays. Furthermore, whether p53 deletion facilitates prostate cancer bone-metastatic capacity was explored using an in vivo bone-metastatic model. The mechanistic model of wt-p53 in regulating gene expression was further explored by a luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay. Results: Our findings revealed that wt-p53 suppressed the prostate cancer cell migration rate, chemotaxis and attachment toward the osteoblasts in vitro. The bone-metastatic model showed that deletion of wt-p53 remarkably increased prostate cancer bone-metastatic capacity in vivo. Mechanistically, wt-p53 could induce the ligand-induced degradation of the chemokine receptor CXCR4 by transcriptionally upregulating the expression of ubiquitin ligase AIP4. Treatment with the CXCR4 inhibitor AMD3100 or transduction of the AIP4 plasmid abrogated the pro-bone metastasis effects of TP53 deletion. Conclusion: Wt-p53 suppresses the metastasis of prostate cancer cells to bones by regulating the CXCR4/CXCL12 activity in the tumor cells/bone marrow microenvironment interactions. Our findings suggest that targeting the wt-p53/AIP4/CXCR4 axis might be a promising therapeutic strategy to manage prostate cancer bone metastasis. [ABSTRACT FROM AUTHOR]

Jun Yeob Kim,1 Rusia Lee,1,2 Gu Xiao,1 Dominique Forbes,1 Jill Bargonetti1– 3 1The Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA; 2Biology PhD Program, The Graduate Center of Biology, City University of New York, New York, NY, USA; 3Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10021, USACorrespondence: Jill Bargonetti The Department of Biological SciencesHunter College, Belfer Building, 413 East 69 th Street, New York, NY 10021, USATel +1 212-896-0465Email bargonetti@genectr.hunter.cuny.eduBackground: Mouse double minute 2 (MDM2) is an E3 ubiquitin ligase that is over-expressed in many cancers and regulates target proteins through ubiquitination. Full-length MDM2 (MDM2-FL) is best known for targeting wild-type p53 for degradation by the proteasome, but the functions of the many splice variants of MDM2 are under-explored. The three well-studied alternative MDM2 isoforms are MDM2-A/ALT2, MDM2-B/ALT1, and MDM2-C/ALT3. MDM2-A and MDM2-B are capable of down-regulating MDM2-FL activity and have transforming activity in cancers with mutant p53. The MDM2 isoform MDM2-C is over-expressed in breast cancer and correlates with decreased survival in the context of mutant p53 expression. Therefore, MDM2-C requires further study to determine if it has biochemical activities similar to MDM2-FL. Hypothesis: We hypothesized that like MDM2-FL, the MDM2-C isoform (lacking exons 5– 9 and containing a full C-terminal RING finger sequence) would maintain E3 ubiquitin ligase activity.Materials and Methods: In order to explore the biochemical function of MDM2-C, we used an in vitro ubiquitination assay and a glutaraldehyde cross-linking assay.Results: Here we report, for the first time, that MDM2-C has E3 auto-ubiquitin ligase activity, which can promote ubiquitination of wild-type p53 and mutant p53 R273H, and also can form a protein–protein interaction with p53 proteins.Conclusion: This information strongly positions MDM2-C as a protein with biochemical activities that may explain the varied outcomes observed in patients with high-level expression of MDM2-C in the presence of wild-type p53 versus mutant p53.Keywords: MDM2 splice variants, mutant p53, wild-type p53, breast cancer

Background: Management of patients with prostate cancer and bone metastatic disease remains a major clinical challenge. Loss or mutation of p53 has been identified to be involved in the tumor progression and metastasis. Nevertheless, direct evidence of a specific role for wild-type p53 (wt-p53) in bone metastasis and the mechanism by which this function is mediated in prostate cancer remain obscure.Methods: The expression and protein levels of wt-53, AIP4, and CXCR4 in prostate cancer cells and clinical specimens were assessed by real-time PCR, immunohistochemistry and western blot analysis. The role of wt-p53 in suppressing aggressive and metastatic tumor phenotypes was assessed using in vitro transwell chemotaxis, wound healing, and competitive colocalization assays. Furthermore, whether p53 deletion facilitates prostate cancer bone-metastatic capacity was explored using an in vivo bone-metastatic model. The mechanistic model of wt-p53 in regulating gene expression was further explored by a luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay.Results: Our findings revealed that wt-p53 suppressed the prostate cancer cell migration rate, chemotaxis and attachment toward the osteoblasts in vitro. The bone-metastatic model showed that deletion of wt-p53 remarkably increased prostate cancer bone-metastatic capacity in vivo. Mechanistically, wt-p53 could induce the ligand-induced degradation of the chemokine receptor CXCR4 by transcriptionally upregulating the expression of ubiquitin ligase AIP4. Treatment with the CXCR4 inhibitor AMD3100 or transduction of the AIP4 plasmid abrogated the pro-bone metastasis effects of TP53 deletion.Conclusion: Wt-p53 suppresses the metastasis of prostate cancer cells to bones by regulating the CXCR4/CXCL12 activity in the tumor cells/bone marrow microenvironment interactions. Our findings suggest that targeting the wt-p53/AIP4/CXCR4 axis might be a promising therapeutic strategy to manage prostate cancer bone metastasis.

The p53 protein has appropriately been named the “guardian of the genome”. In almost all human cancers, the powerful tumor suppressor function of p53 is compromised by a variety of mechanisms, including mutations with either loss of function or gain of function and inhibition by its negative regulators MDM2 and/or MDMX. We review herein the progress made on different therapeutic strategies for targeting p53.

Treatment of brain cancers, especially high grade gliomas (WHO stage III and IV) is slowly making progress, but not as fast as medical researchers and the patients would like. Immunotherapy offers the opportunity to allow the patient's own immune system a chance to help eliminate the cancer. Immunotherapy's strength is that it efficiently treats relatively small tumors in experimental animal models. For some patients, immunotherapy has worked for them while not showing long-term toxicity. In this paper, we will trace the history of immunotherapy for brain cancers. We will also highlight some of the possible directions that this field may be taking in the immediate future for improving this therapeutic option.

The study of the cancer secretome is gaining even more importance in cancers such as pancreatic ductal adenocarcinoma (PDAC), whose lack of recognizable symptoms and early detection assays make this type of cancer highly lethal. The wild-type p53 protein, frequently mutated in PDAC, prevents tumorigenesis by regulating a plethora of signaling pathways. The importance of the p53 tumor suppressive activity is not only primarily involved within cells to limit tumor cell proliferation but also in the extracellular space. Thus, loss of p53 has a profound impact on the secretome composition of cancer cells and marks the transition to invasiveness. Here, we demonstrate the tumor suppressive role of wild-type p53 on cancer cell secretome, showing the anti-proliferative, apoptotic and chemosensitivity effects of wild-type p53 driven conditioned medium. By using high-resolution SWATH-MS technology, we characterized the secretomes of p53-deficient and p53-expressing PDAC cells. We found a great number of secreted proteins that have known roles in cancer-related processes, 30 of which showed enhanced and 17 reduced secretion in response to p53 silencing. These results are important to advance our understanding on the link between wt-p53 and cancer microenvironment. In conclusion, this approach may detect a secreted signature specifically driven by wild-type p53 in PDAC.

Introduction: Glioma is the most common malignant brain tumor. TP53 is the most common mutant gene in human cancer. Wild-type p53 (wtp53) is a tumor suppressor protein whereas mutant p53 (mutp53) is an oncoprotein that promotes tumor cell proliferation. Our aim was to examine the inhibitory effects of berberine on the proliferation of human glioma cells via regulation of wtp53, mutp53, and their downstream molecules. Methods: We selected wtp53 cells (U87 cells) and mutp53 cells (U251 cells termed p53 R273H) to examine the inhibitory effects of berberine on human glioma cells. We used the CCK-8 kit to detect the toxic effect of berberine. Flow cytometry was used to detect the effect of berberine. Clone formation test was used to test the inhibitory effect of berberine on the proliferation of glioma cells. Western blot was used to detect the changes of related proteins such as p53, p-p53, p21 and cyclin D1. Lentivirus transduction was used to transduce wild-type p53 into U251 cells to further examine the effect of berberine. The nude mouse subcutaneous tumor model was used to detect the effect of berberine on inhibiting the proliferation of glioma cells in vivo. Results: Berberine promoted the phosphorylation of wtp53, increased the expression of p21 protein, reduced cyclin D1 content, and caused G1 phase arrest in U87 cells. Berberine also reduced mutp53 content and caused G2 phase arrest in U251 cells with a concurrent decrease in p21, cyclin D1, and cyclin B1 content. Transduction with wtp53 enhanced the effects on cell cycle arrest. Further, berberine significantly inhibited glioma growth in vivo mouse tumor model. Discussion: Glioma is a group of heterogeneous brain tumors with unique biological and clinical characteristics. Berberine can inhibit glioma cells through a variety of ways. Our research indicated that berberine inhibited the proliferation of glioma cells by interfering with wtp53 and mutp53. This indicates that berberine could be used as a potential drug to treat wild-type and mutant p53 glioma. [ABSTRACT FROM AUTHOR]

The tumor suppressor p53 is a key mediator of cellular stress and DNA damage response cascades and is activated after exposure to ionizing radiation. Amplifying wild-type p53 expression by targeting negative regulators such as MDM2 in combination with external beam radiotherapy (EBRT) may result in increased therapeutic effects. The novel stapled peptide PM2 prevents MDM2 from suppressing wild-type p53, and is thus a promising agent for therapeutic combination with EBRT. Effects of PM2 and potential PM2-induced radiosensitivity were assessed in a panel of cancer cell lines using 2D cell viability assays. Western Blot and flow cytometric analyses were used to investigate the mechanisms behind the observed effects in samples treated with PM2 and EBRT. Finally, PM2-treatment combined with EBRT was evaluated in an in vitro 3D spheroid model. PM2-therapy decreased cell viability in wild-type p53, HPV-negative cell lines. Western Blotting and flow cytometry confirmed upregulation of p53, as well as initiation of p53-mediated apoptosis measured by increased cleaved caspase-3 and Noxa activity. Furthermore, 3D in vitro tumor spheroid experiments confirmed the superior effects of the combination, as the only treatment regime resulting in growth inhibition and complete spheroid disintegration. We conclude that PM2 induces antitumorigenic effects in wt p53 HPV-negative cancer cells and potentiates the effects of EBRT, ultimately resulting in tumor eradication in a 3D spheroid model. This strategy shows great potential as a new wt p53 specific tumor-targeting compound, and the combination of PM2 and EBRT could be a promising strategy to increase therapeutic effects and decrease adverse effects from radiotherapy.

The tumor suppressor p53 is a key mediator of cellular stress and DNA damage response cascades and is activated after exposure to ionizing radiation. Amplifying wild-type p53 expression by targeting negative regulators such as MDM2 in combination with external beam radiotherapy (EBRT) may result in increased therapeutic effects. The novel stapled peptide PM2 prevents MDM2 from suppressing wild-type p53, and is thus a promising agent for therapeutic combination with EBRT. Effects of PM2 and potential PM2-induced radiosensitivity were assessed in a panel of cancer cell lines using 2D cell viability assays. Western Blot and flow cytometric analyses were used to investigate the mechanisms behind the observed effects in samples treated with PM2 and EBRT. Finally, PM2-treatment combined with EBRT was evaluated in an in vitro 3D spheroid model. PM2-therapy decreased cell viability in wild-type p53, HPV-negative cell lines. Western Blotting and flow cytometry confirmed upregulation of p53, as well as initiation of p53-mediated apoptosis measured by increased cleaved caspase-3 and Noxa activity. Furthermore, 3D in vitro tumor spheroid experiments confirmed the superior effects of the combination, as the only treatment regime resulting in growth inhibition and complete spheroid disintegration. We conclude that PM2 induces antitumorigenic effects in wt p53 HPV-negative cancer cells and potentiates the effects of EBRT, ultimately resulting in tumor eradication in a 3D spheroid model. This strategy shows great potential as a new wt p53 specific tumor-targeting compound, and the combination of PM2 and EBRT could be a promising strategy to increase therapeutic effects and decrease adverse effects from radiotherapy. [ABSTRACT FROM AUTHOR]

A significant loss of p53 protein, an anti‐tumour agent, is observed in early cancerous cells. Induction of small molecules based drug is by far the most prominent technique to revive and maintain wild‐type p53 to the desired level. In this study, a sliding mode control (SMC) based robust non‐linear technique is presented for the drug design of a control‐oriented p53 model. The control input generated by conventional SMC is discontinuous; however, depending on the physical nature of the system, drug infusion needs to be continuous. Therefore, to obtain a smooth control signal, a dynamic SMC (DSMC) is designed. Moreover, the boundedness of the zero‐dynamics is also proved. To make the model‐based control design possible, the unknown states of the system are estimated using an equivalent control based, reduced‐order sliding mode observer. The robustness of the proposed technique is assessed by introducing input disturbance and parametric uncertainty in the system. The effectiveness of the proposed control scheme is witnessed by performing in‐silico trials, revealing that the sustained level of p53 can be achieved by controlled drug administration. Moreover, a comparative quantitative analysis shows that both controllers yield similar performance. However, DSMC consumes less control energy. [ABSTRACT FROM AUTHOR]

The tumor suppressor protein p53 is often called “the genome guardian” and controls the cell cycle and the integrity of DNA, as well as other important cellular functions. Its main function is to trigger the process of apoptosis in tumor cells, and approximately 50% of all cancers are related to the inactivation of the p53 protein through mutations in the TP53 gene. Due to the association of mutant p53 with cancer therapy resistance, different forms of restoration of p53 have been subject of intense research in recent years. In this sense, this review focus on the main currently adopted approaches for activation and reactivation of p53 tumor suppressor function, focusing on the synthetic approaches that are involved in the development and preparation of such small molecules.

Gene mutations and functional inhibition are the major obstacles for p53-mediated oncotherapy. For p53-wild-type tumors, the underlying mechanisms of functional inhibition of p53 during oncogenesis are unknown. The results reveal that the expression of the MDM2 inhibitor ARF is inhibited in p53-wild-type tumors, indicating that the restoration of ARF could be a potential oncotherapy strategy for p53-wild-type tumors. Therefore, ARF-mimetic MDM2-targeting reassembly peptide nanoparticles (MtrapNPs) for p53-based tumor therapy is developed. The results elucidated that the MtrapNPs respond to and form a nanofiber structure with MDM2. By trapping MDM2, the MtrapNPs stabilize and activate p53 for the inhibition of p53-wild-type tumors. In most cases, reactivated mutant p53 is inhibited and degraded by MDM2. In the present study, MtrapNPs are used to load and deliver arsenic trioxide, a p53 mutation rescuer, for p53-mutated tumor treatment in both orthotopic and metastatic models, and they exhibit significant therapeutic effects. Therefore, the study provides evidence supporting a link between decreased ARF expression and tumor development in patients with p53-wild-type tumors. Thus, the MDM2-trap strategy, which addresses both the inhibition and mutations of p53, is an efficient strategy for the treatment of p53-mutated tumors., (© 2023 Wiley-VCH GmbH.)

Abstract: Colorectal cancer (CRC) is one of the leading causes of cancer‐related deaths worldwide. Chemoresistance is a major problem for effective therapy in CRC. Here, we investigated the mechanism by which peptidylprolyl isomerase B (PPIB; cyclophilin B, CypB) regulates chemoresistance in CRC. We found that CypB is a novel wild‐type p53 (p53WT)‐inducible gene but a negative regulator of p53WT in response to oxaliplatin treatment. Overexpression of CypB shortens the half‐life of p53WT and inhibits oxaliplatin‐induced apoptosis in CRC cells, whereas knockdown of CypB lengthens the half‐life of p53WT and stimulates p53WT‐dependent apoptosis. CypB interacts directly with MDM2, and enhances MDM2‐dependent p53WT ubiquitination and degradation. Furthermore, we firmly validated, using bioinformatics analyses, that overexpression of CypB is associated with poor prognosis in CRC progression and chemoresistance. Hence, we suggest a novel mechanism of chemoresistance caused by overexpressed CypB, which may help to develop new anti‐cancer drugs. We also propose that CypB may be utilized as a predictive biomarker in CRC patients. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background: Defects in modulating wild-type (wt) p53 and survivin are associated with a resistant disease in acute lymphoblastic leukemia (ALL). Yet, no wt-p53 and survivin modulating drugs have been approved for clinical application in ALL. Here, we investigated if in vitro eicosapentaenoic acid (EPA) concentrations equal to human plasma levels are able to target wt-p53 and survivin. Methods: Wt-p53 Molt-4 cells (ALL cell line) were treated with 50, 100, 150, and 200 µM of EPA after which cell number, viability, proliferation rate, survivin expression, wt-p53 accumulation, caspase-3 activation, and apoptosis were evaluated. Results: After 48- and 72-h treatments with EPA at concentrations ranging from 50 to 200 µM, cell proliferation rates were measured to be 71.5–32.6% and 68.2–13.7% and metabolic activities were measured to be 77–44% and 71–26%, respectively. Treatment with 50–200 µM of EPA for 48 h resulted in 14.1–74.6% and 69.5–45.5% decreases in survivin mRNA and protein levels, respectively. EPA induced 1.3–6 and 1.9–20-fold increases in caspase-3 activation and wt-p53 accumulation, respectively. Increase in wt-p53/survivin and caspase-3/survivin ratios from 1 in untreated cells to 20.3 and 5.8 was measured for 150 µM of EPA. Low necrotic rates ranging from 0.3% to 2.8% and an increase in the number of total apoptotic cells (early + late) ranging from 9.8% to 81% were also observed with increasing EPA concentrations. Conclusion: EPA induces strongly wt-p53 with a remarkable decrease in survivin expression, representing an attractive compound to modulate wt-p53 and survivin in ALL cells. [ABSTRACT FROM AUTHOR]

The authors have proposed a systems theory‐based novel drug design approach for the p53 pathway. The pathway is taken as a dynamic system represented by ordinary differential equations‐based mathematical model. Using control engineering practices, the system analysis and subsequent controller design is performed for the re‐activation of wild‐type p53. p53 revival is discussed for both modes of operation, i.e. the sustained and oscillatory. To define the problem in control system paradigm, modification in the existing mathematical model is performed to incorporate the effect of Nutlin. Attractor point analysis is carried out to select the suitable domain of attraction. A two‐loop negative feedback control strategy is devised to drag the system trajectories to the attractor point and to regulate cellular concentration of Nutlin, respectively. An integrated framework is constituted to incorporate the pharmacokinetic effects of Nutlin in the cancerous cells. Bifurcation analysis is also performed on the p53 model to see the conditions for p53 oscillation. [ABSTRACT FROM AUTHOR]

Prostate cancer is a common type of cancer in elderly men. The aim of the present study was to evaluate the effects of ultrasound exposure in combination with SonoVue microbubbles on liposome-mediated transfection of wild-type P53 genes into human prostate cancer cells. PC-3 human prostate cancer cells were exposed to ultrasound; duty cycle was controlled at 20% (2 sec on, 8 sec off) for 5 min with and without SonoVue microbubble echo-contrast agent using a digital sonifier (frequency, 21 kHz; intensity, 46 mW/cm2). The cells were divided into eight groups, as follows: Group A (SonoVue + wild-type P53), group B (ultrasound + wild-type P53), group C (SonoVue + ultrasound + wild-type P53), group D (liposome + wild-type P53), group E (liposome + SonoVue + wild-type P53), group F (liposome + wild-type P53 + ultrasound), group G (liposome + wild-type P53 + ultrasound + SonoVue) and the control group (wild-type P53). Following treatment, a hemocytometer was used to measure cell lysis, reverse transcription-quantitative polymerase chain reaction and western blotting were performed to detect P53 gene transfection efficiency, Cell Counting Kit-8 was employed to reveal cell proliferation and Annexin V/propidium iodide staining was used to determine cell apoptosis. Cell lysis was minimal in each group. Wild-type P53 gene and protein expression were significantly increased in the PC-3 cells in group G compared with the control and all other groups (P<0.01). Cell proliferation was significantly suppressed in group G compared with the control group and all other groups (P<0.01). Cell apoptosis levels in group G were significantly improved compared with the control group and all other groups (P<0.01). Thus, the results of the present study indicate that the use of low-frequency and low-energy ultrasound in combination with SonoVue microbubbles may be a potent physical method for increasing liposome gene delivery efficiency. [ABSTRACT FROM AUTHOR]

The transcription factor p53 is an important regulator of a multitude of cellular processes. In the presence of genotoxic stress, p53 is activated to facilitate DNA repair, cell cycle arrest, and apoptosis. In breast cancer, the tumor suppressive activities of p53 are frequently inactivated by either the overexpression of its negative regulator MDM2, or mutation which is present in 30-35% of all breast cancer cases. Notably, the frequency of p53 mutation is highly subtype dependent in breast cancers, with majority of hormone receptor-positive or luminal subtypes retaining the wild-type p53 status while hormone receptor-negative patients predominantly carry p53 mutations with gain-of-function oncogenic activities that contribute to poorer prognosis. Thus, a two-pronged strategy of targeting wild-type and mutant p53 in different subtypes of breast cancer can have clinical relevance. The development of p53-based therapies has rapidly progressed in recent years, and include unique small molecule chemical inhibitors, stapled peptides, PROTACs, as well as several genetic-based approaches using vectors and engineered antibodies. In this review, we highlight the therapeutic strategies that are in pre-clinical and clinical development to overcome p53 inactivation in both wild-type and mutant p53-bearing breast tumors, and discuss their efficacies and limitations in pre-clinical and clinical settings., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Genistein (GEN) has been previously shown to have a proapoptotic effect on cancer cells through a p53-dependent pathway, the mechanism of which remains unclear. One of its intracellular targets, APE1, protects against apoptosis under genotoxic stress and interacts with p53. In this current study, we explored the mechanism of the proapoptotic effect of GEN by examining the APE1–p53 protein–protein interaction. We initially showed that the p53 protein level was elevated in GEN-treated human non-small lung cancer A549 cells and cervical cancer HeLa cells. By examining both protein synthesis and degradation, we found that GEN enhances p53 intracellular stability by interfering with the interaction of APE1 and p53, which provided a plausible explanation for how GEN initiates apoptosis. Furthermore, we found that the interaction between APE1 and p53 is important for the degradation of p53 and is dependent on the redox domain of APE1 by utilizing the redox domain mutant APE1 C65A. Our data suggest that the degradation of wild-type p53 is blocked when the redox domain of APE1 is masked or interrupted. Based on this evidence, we hereby report a novel mechanism of p53 degradation through an APE1-mediated, redox-dependent pathway. [ABSTRACT FROM AUTHOR]

Among the tumor suppressor genes, p53 is one of the most studied. It is widely regarded as the “guardian of the genome”, playing a major role in carcinogenesis. In fact, direct inactivation of the TP53 gene occurs in more than 50% of malignancies, and in tumors that retain wild-type p53 status, its function is usually inactivated by overexpression of negative regulators (e.g., MDM2 and MDMX). Hence, restoring p53 function in cancer cells represents a valuable anticancer approach. In this review, we will present an updated overview of the most relevant small molecules developed to restore p53 function in cancer cells through inhibition of the p53-MDMs interaction, or direct targeting of wild-type p53 or mutated p53. In addition, optimization approaches used for the development of small molecules that have entered clinical trials will be presented.

The p53 protein has appropriately been named the "guardian of the genome". In almost all human cancers, the powerful tumor suppressor function of p53 is compromised by a variety of mechanisms, including mutations with either loss of function or gain of function and inhibition by its negative regulators MDM2 and/or MDMX. We review herein the progress made on different therapeutic strategies for targeting p53.

Abstract: Objective: The objective of this study is to investigate whether wild-type TP53 status in high-grade serous ovarian carcinoma is associated with poorer survival. Methods: Clinical and genomic data of 316 sequenced samples from The Cancer Genome Atlas (TCGA) ovarian high-grade serous carcinoma study were downloaded from TCGA data portal. Association between wild-type TP53 and survival was analyzed with Kaplan Meier method and Cox regression. The diagnosis of high-grade serous carcinomas was evaluated by reviewing pathological reports and high-resolution hematoxylin and eosin (H&E) images from frozen sections. The authenticity of wild-type TP53 in these tumor samples was assessed by analyzing SNP array data with ASCAT algorithm, reverse phase protein array (RPPA) data and RNAseq data. Results: Fifteen patients with high grade serous ovarian carcinomas were identified to have wild-type TP53, which had significantly shorter survival and higher chemoresistance than those with mutated TP53. The authenticity of wild-type TP53 status in these fifteen patients was supported by SNP array, RPPA, and RNAseq data. Except four cases with mixed histology, the classification as high grade serous carcinomas was supported by pathological reports and H&E images. Using RNAseq data, it was found that EDA2R gene, a direct target of wild-type TP53, was highly up-regulated in samples with wild-type TP53 in comparison to samples with either nonsense or missense TP53 mutations. Conclusion: Although patients with wild-type TP53 ovarian cancer were rare in the TCGA high grade ovarian serous carcinomas cohort, these patients appeared to have a poorer survival and were more chemoresistant than those with mutated TP53. Differentially expressed genes in these TP53 wild-type tumors may provide insight in the molecular mechanism in chemotherapy resistance. [Copyright &y& Elsevier]

Abstract: One of the best characterized resistance mechanisms of human cancer is multidrug resistance (MDR) mediated by P-glycoprotein (Pgp/MDR1) and multidrug-resistant related protein (MRP1). In addition to Pgp/MDR1 and MRP1, p53 inactivation or mutation might play a relevant role in therapeutic failure. This study involved 25 children (17 girls and 8 boys) aged 7 months to 10 years treated for unilateral Wilms’ tumor. 25 tissue samples of Wilms’ tumor and 5 samples of normal human kidneys were obtained from the Department of Pathological Anatomy, Jessenius Faculty of Medicine in Martin, Slovak Republic. We used an indirect immunohistochemical method to determine expression of Pgp/MDR1, MRP1 and wild-type p53 in 25 tissue samples of nephroblastoma. The minority of nephroblastoma specimens showed positivity for both MDR proteins, as well as for wild-type p53. 24% of tissue samples revealed positive results for Pgp/MDR1, 48% for MRP1 and 8% for wild-type p53. Furthermore, our study showed a statistically significant difference between p53 and MRP1 protein expression (p <0.01), but not between p53 and Pgp/MDR1 (p >0.05). No correlation was found between the expression of both multidrug resistance proteins (Pgp/MDR1 and MRP1) and the expression of wild-type p53. Immunohistochemical detection of the expression of MDR proteins and wild-type p53 at the time of diagnosis might assist in choosing specific chemotherapeutics to improve prognosis and therapy. [Copyright &y& Elsevier]

The p53 protein is a tumor suppressor encoded by the TP53 gene and consists of 393 amino acids with four main functional domains. This protein responds to various cellular stresses to regulate the expression of target genes, thereby causing DNA repair, cell cycle arrest, apoptosis, metabolic changes, and aging. Mutations in the TP53 gene and the functions of the wild-type p53 protein (wtp53) have been linked to various human cancers. Eight TP53 gene mutations are located in codons, constituting 28% of all p53 mutations. The p53 can be used as a biomarker for tumor progression and an excellent target for designing cancer treatment strategies. In wild-type p53-carrying cancers, abnormal signaling of the p53 pathway usually occurs due to other unusual settings, such as high MDM2 expression. These differences between cancer cell p53 and normal cells have made p53 one of the most important targets for cancer treatment. In this review, we have dealt with various issues, such as the relative contribution of wild-type p53 loss of function, including transactivation-dependent and transactivation-independent activities in oncogenic processes and their role in cancer development. We also discuss the role of p53 in the process of ferroptosis and its targeting in cancer treatment. Finally, we focus on p53-related drug delivery systems and investigate the challenges and solutions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Babamohamadi, Babaei, Ahmed Salih, Babamohammadi, Jalal Azeez and Othman.)

Abstract: The combination of gene therapy and chemotherapy may increase the therapeutic efficacy in the treatment of patients. In this work, the cationic polymer prodrug/plasmid nanocomplexes were designed to in vivo synergistically treat drug-resistant breast tumors. Cationic β-cyclodextrin-polyethylenimine-Dox (PC-Dox) conjugates were prepared for carrying wt p53 plasmid in the form of PC-Dox/p53 nanocomplexes to achieve synergistic cancer therapeutic effects of drug and gene therapies. Such PC-Dox/p53 nanocomplexes ensure that both drug and gene can be delivered to the same cancer cells. The physicochemical properties and Dox release profiles of the PC-Dox conjugates, as well as their antitumor activities in vitro and in vivo, were determined. mRNA expression and western blot experiments also proved that co-delivery of Dox with wt p53 plasmid from PC-Dox/wt p53 complexes could promote wt p53 gene expression largely. By investigating anticancer efficacy via multi-drug resistant MCF-7/Adr breast cancer cells, it was found that PC-Dox/wt p53 complexes promoted the inhibition of tumor growth in vivo and prolonged the survival time of tumor-bearing mice. With the efficient ability to co-deliver drug and gene, such multifunctional PC-Dox/pDNA complexes should have great potential applications in cancer therapy. [Copyright &y& Elsevier]

Abstract: Breast cancer resistance protein (BCRP) has been shown to confer multidrug resistance, but the mechanisms of its regulation are poorly understood. Here, we investigate the effects of wild-type and mutant p53, and nuclear factor kappa-B (NF-κB) (p50) on BCRP promoter activity in MCF-7 cells. Our results demonstrated that wild-type p53 markedly suppressed BCRP activity and enhanced the chemosensitivity of cells to mitoxantrone, whereas mutant p53 had little inhibitory effect. After inhibition of NF-κB, similar results were obtained. Following knockdown of endogenous p53, BCRP and p50 expressions were increased, and the chemosensitivity of the cells to mitoxantrone was decreased. We conclude that wild-type p53 acts as a negative regulator of BCRP gene transcription. [ABSTRACT FROM AUTHOR]

The study of the cancer secretome is gaining even more importance in cancers such as pancreatic ductal adenocarcinoma (PDAC), whose lack of recognizable symptoms and early detection assays make this type of cancer highly lethal. The wild-type p53 protein, frequently mutated in PDAC, prevents tumorigenesis by regulating a plethora of signaling pathways. The importance of the p53 tumor suppressive activity is not only primarily involved within cells to limit tumor cell proliferation but also in the extracellular space. Thus, loss of p53 has a profound impact on the secretome composition of cancer cells and marks the transition to invasiveness. Here, we demonstrate the tumor suppressive role of wild-type p53 on cancer cell secretome, showing the anti-proliferative, apoptotic and chemosensitivity effects of wild-type p53 driven conditioned medium. By using high-resolution SWATH-MS technology, we characterized the secretomes of p53-deficient and p53-expressing PDAC cells. We found a great number of secreted proteins that have known roles in cancer-related processes, 30 of which showed enhanced and 17 reduced secretion in response to p53 silencing. These results are important to advance our understanding on the link between wt-p53 and cancer microenvironment. In conclusion, this approach may detect a secreted signature specifically driven by wild-type p53 in PDAC. [ABSTRACT FROM AUTHOR]

Abstract: The tumor suppressor p53 controls a broad range of cellular responses. Induction of a transient (cell cycle arrest) or a permanent (senescence) block of cell proliferation, or the activation of cell death pathways in response to genotoxic stress comprise the major arms of the survival-death axis governed by p53. Due to these biological properties, inactivation of p53 is a crucial step in tumor development and progression, reflected by the high incidence of TP53 mutations in different types of human cancers. The remarkable potency of p53 in suppressing tumorigenic outgrowth has promoted the expectation that tumor cells expressing wild-type p53 (wtp53) should be more prone to elimination by cytotoxic treatments than tumor cells expressing mutant p53 (mutp53) with defunct wtp53 activities. However, recent findings yielded somewhat unexpected insights concerning the preponderance of the survival-promoting effects of wtp53 in cancer cells, a rather undesired property from the therapeutic point of view. In this commentary we will discuss the possibility that the developmentally established distinct patterns of wtp53 mediated responses in different tissues are an important factor in determining the ultimate outcome of cellular responses mediated by wtp53 in different types of tumor cells, with a particular focus on the divergent impact of wtp53 in malignant tumors of the central nervous system. We infer that a selective gain of pro-survival functions of wtp53 in cancer cells will confer a survival advantage that counteracts tumor therapy. [Copyright &y& Elsevier]

When normal cells come under stress, the wild-type (WT) p53 level increases resulting in the regulation of gene expression responsible for growth arrest or apoptosis. Here we show that elevated levels of WT p53 or its homologue, p73, inhibit expression of a number of cell cycle regulatory and growth promoting genes. Our analysis also identified a group of genes whose expression is differentially regulated by WT p53 and p73. We have infected p53-null H1299 human lung carcinoma cells with recombinant adenoviruses expressing WT p53, p73 or β-galactosidase, and have undertaken microarray hybridization analyses to identify genes whose expression profile is altered by p53 or p73. Quantitative real-time PCR verified the repression of E2F-5, centromere protein A and E, minichromosome maintenance proteins (MCM)-2, -3, -5, -6 and -7 and human CDC25B after p53 expression. 5-Fluorouracil treatment of colon carcinoma HCT116 cells expressing WT p53 results in a reduction of the cyclin B2 protein level suggesting that DNA damage may indeed cause repression of these genes. Transient transcriptional assays verified that WT p53 repressed promoters of a number of these genes. Interestingly, a gain-of-function p53 mutant instead upregulated a number of these promoters in transient transfection. Using promoter deletion mutants of MCM-7 we have found that WT p53-mediated repression needs a minimal promoter that contains a single E2F site and surrounding sequences. However, a single E2F site cannot be significantly repressed by WT p53. Many of the genes identified are also repressed by p21. Thus, our work shows that WT p53 and p73 repress a number of growth-related genes and that in many instances this repression may be through the induction of p21.Oncogene (2008) 27, 2583–2593; doi:10.1038/sj.onc.1210898; published online 5 November 2007 [ABSTRACT FROM AUTHOR]

Bombesin (BN) or gastrin-releasing peptide (GRP) can stimulate the growth of neoplasms such as breast cancer and small-cell lung carcinoma (SCLC). Antagonists of BN/GRP have been shown to inhibit these cancers. We evaluated whether antagonists of BN/GRP can suppress the growth of human non-SCLC (NSCLC) xenografted into nude mice. The effect of the administration of BN/GRP antagonist RC-3940-II on the growth of H460 and A549 NSCLC cell lines orthotopically xenografted into the intrapulmonary interstitium was examined. Protein levels of K-Ras, COX-2, Akt/pAkt, WT p53, Erk1/2, and lung resistance-related protein (LRP) in tumors were analyzed by Western blot analaysis, and receptors for BN/GRP were investigated by radioligand-binding studies. The effect of RC-3940-ll on the proliferation of H460 and A549 cells in vitro was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays. High-affinity receptors for BN/GRP were found on tumors. Treatment with RC-3940-Il significantly (P < 0.001) inhibited growth of H460 and A549 NSCLC xenografts by 30-50% and led to an improved performance status, compared with controls. In H460 NSCLC, the antitumor effect was associated with a significant (P < 0.001) reduction in protein levels of K-Ras, COX-2, pAkt, and pERK1/2 and with a major augmentation in the expression of WT p53, compared with controls. In A549 NSCLC, pAkt and LRP were significantly down-regulated. Our findings demonstrate the efficacy of BN/GRP antagonist RC-3940-lI for the treatment of NSCLC. The suppression of K-Ras, COX-2, pAkt, and LRP, as well as the up-regulation of WT p53 might contribute to the antitumor action of BN/GRP antagonists. [ABSTRACT FROM AUTHOR]

To clarify the role of p53 in 22 hepatitis C virus (HCV)-infected hepatocellular carcinomas (HCCs), we compared the gene expression profiles of HCCs with wild-type p53 (wt-p53) (n=17) and those with mutant-type p53 (mt-p53) (n=5) by oligonucleotide microarray analysis. Among 83 p53-related genes identified by a supervised learning method, 25 were underexpressed, and 58 were overexpressed in mt-p53 HCCs compared with wt-p53 HCCs. With a computer search, we identified consensus p53-binding sequences in the 3-kb region upstream of the translation initiation site in 59 of the 83 genes, suggesting that the in vivo p53-associated transcription system is very complicated. These data will provide additional insights into p53-related pathogenesis in HCV-infected HCC. [Copyright &y& Elsevier]