The MDM2 gene family

Elucidating the transcriptomic response of adult-derived mHypoA-2/12 mouse hypothalamic neuron cell line to cannabidiol (CBD) exposure

Cannabidiol (CBD) is a compound found in Cannabis sativa that is known for its neuroprotective, anti-inflammatory, analgesic, and anxiolytic properties. These properties make it a promising treatment for various neurological conditions. This study aimed to examine the effects of CBD on hypothalamic neurons at the transcriptome level using the adult-derived mHypoA-2/12 mouse cell line. The cells were exposed to four different CBD concentrations (ranging from 0.325 to 3 µM) for 6 and 24 h. Apart from the transcriptome analysis, apoptosis (caspase 3/7 activity) and viability (MTT) assays were performed. The obtained results showed that CBD enhanced cell viability, especially after 24 h of treatment and at lower or intermediate concentrations, and reduced apoptosis, with significant effects at the highest concentration. CBD caused moderate transcriptome profile changes (13 to 69 genes per treatment), with more genes affected at higher concentrations and shorter exposure times, indicating a stronger initial cellular response. Further analysis revealed that CBD affects several biological processes, including: intrinsic apoptosis suppression via p53 modulation, impacting genes like Bbc3, Mdm2, Cdkn1a, and Smad3. Additionally, CBD influenced genes involved in extracellular matrix organization, including metalloproteinases (Mmp-3, Mmp-13) and their inhibitors (Timp1), as well as collagen components (Col11a1) and mitochondrial respiratory chain complexes (mt-Nd5, mt-Nd4). Genes related to serotonin and dopamine biosynthesis, as well as Aldh2, were also impacted, linking CBD's effects in hypothalamic neurons to potential benefits in managing alcohol use disorders. These findings suggest the hypothalamus is a significant target for CBD, warranting further investigation.

The effects of flavonoid baicalein on miRNA expressions in cancer: a systematic review

Baicalein from Scutellaria baicalensis influences miRNA expression in various cancers, affecting key signaling pathways (PI3K/AKT, Wnt/β-catenin, mTOR) and processes like tumor growth, apoptosis, and metastasis. miRNAs, as small non-coding RNAs, play crucial roles in the cancer pathogenesis-associated gene regulations. This study is aimed at systematically reviewing the effects of baicalein on miRNA expression in various cancers. A comprehensive systematic review was conducted following PRISMA guidelines to investigate the impact of baicalein on miRNA expression in cancer. Databases including PubMed, Scopus, and Web of Science were systematically searched using key search terms. Inclusion criteria encompassed studies reporting changes in miRNA expression following baicalein treatment in cancer cell lines and animal models. Data extraction and risk of bias assessment based on SYRCLE's risk of bias tool were performed to ensure methodological rigor and reliability of the findings. Fifteen studies meeting the inclusion criteria were included in the systematic review. Baicalein impacts miRNA expression in cancers like hepatocellular carcinoma, breast, cervical, ovarian, and gastric cancers, suggesting its potential as a multi-cancer therapeutic. Baicalein regulates tumor-related genes (HDAC10, MDM2, Bcl-2/Bax, and Cyclin E1) and signaling molecules (AKT, FOXO3α), affecting cell viability, apoptosis, and cell cycle, indicating targeted therapeutic potential. In vitro and in vivo studies show baicalein inhibits tumor growth, enhances apoptosis, and regulates cell proliferation, supporting its anticancer effects. Baicalein exhibits potential in modulating miRNA expression in cancer, offering avenues for therapeutic intervention. However, methodological rigor in future studies is essential to enhance the reliability and validity of findings. Comprehensive understanding of baicalein's effects on miRNA expression holds promise for developing novel cancer treatment strategies.

Journey of PROTAC: From Bench to Clinical Trial and Beyond

Proteolysis-targeting chimeras (PROTACs) represent a transformative advancement in drug discovery, offering a method to degrade specific intracellular proteins. Unlike traditional inhibitors, PROTACs are bifunctional molecules that target proteins for elimination, enabling the potential treatment of previously "undruggable" proteins. This concept, pioneered by Crews and his team, introduced the use of small molecules to link a target protein to an E3 ubiquitin ligase, inducing ubiquitination and subsequent degradation of the target protein. By promoting protein degradation rather than merely inhibiting function, PROTACs present a novel therapeutic strategy with enhanced specificity and effectiveness, especially in areas such as cancer and neurodegenerative diseases. Since their initial discovery, the field of PROTAC research has rapidly expanded with numerous PROTACs now designed to target a wide range of disease-relevant proteins. The substantial research, investment, and collaboration across academia and the pharmaceutical industry reflect the growing interest in PROTACs. This Review discusses the journey of PROTACs from initial discovery to clinical trials, highlighting advancements and challenges. Additionally, recent developments in fluorescent and photogenic PROTACs, used for real-time tracking of protein degradation, are presented, showcasing the evolving potential of PROTACs in targeted therapy.

New Synthetic Analogs of Natural 5Z,9Z-Dienoic Acids-Hybrid Molecules Based on Oleanolic Acid: Synthesis and Study of Antitumor Activity

Objectives: A series of synthetic analogs of natural (5Z,9Z)-diene acids were synthesized for the first time in the form of hybrid molecules containing an oleanolic acid fragment. This fragment was simultaneously linked by an amide bond to various hetero- and carbocyclic amines and a complex ester bond to (5Z,9Z)-tetradeca-5,9-dienecarboxylic acid, which was synthesized by a new reaction of Ti-catalyzed homocyclomagnification of 1,2-dienes. Results: Among the synthesized hybrids, the highest cytotoxic activity was observed for compound 9a in the series of Jurkat, K562, U937, and HEK293, with IC50 values of 4.5; 3.1; 2.8; and 26.17 μM/L, respectively. Furthermore, the synthesized compound 9a has been observed to induce apoptosis and exhibit genotoxicity in Jurkat culture, which suggests that it may be a promising candidate for further investigation as an antitumor agent.

Crosstalk between BER and NHEJ in XRCC4-Deficient Cells Depending on hTERT Overexpression

Targeting DNA repair pathways is an important strategy in anticancer therapy. However, the unrevealed interactions between different DNA repair systems may interfere with the desired therapeutic effect. Among DNA repair systems, BER and NHEJ protect genome integrity through the entire cell cycle. BER is involved in the repair of DNA base lesions and DNA single-strand breaks (SSBs), while NHEJ is responsible for the repair of DNA double-strand breaks (DSBs). Previously, we showed that BER deficiency leads to downregulation of NHEJ gene expression. Here, we studied BER's response to NHEJ deficiency induced by knockdown of NHEJ scaffold protein XRCC4 and compared the knockdown effects in normal (TIG-1) and hTERT-modified cells (NBE1). We investigated the expression of the XRCC1, LIG3, and APE1 genes of BER and LIG4; the Ku70/Ku80 genes of NHEJ at the mRNA and protein levels; as well as p53, Sp1 and PARP1. We found that, in both cell lines, XRCC4 knockdown leads to a decrease in the mRNA levels of both BER and NHEJ genes, though the effect on protein level is not uniform. XRCC4 knockdown caused an increase in p53 and Sp1 proteins, but caused G1/S delay only in normal cells. Despite the increased p53 protein, p21 did not significantly increase in NBE1 cells with overexpressed hTERT, and this correlated with the absence of G1/S delay in these cells. The data highlight the regulatory function of the XRCC4 scaffold protein and imply its connection to a transcriptional regulatory network or mRNA metabolism.

Non-Cytotoxic Graphene Nanoplatelets Upregulate Cell Proliferation and Self-Renewal Genes of Mesenchymal Stem Cells

Graphene nanoplatelets (UGZ-1004) are emerging as a promising biomaterial in regenerative medicine. This study comprehensively evaluates UGZ-1004, focusing on its physical properties, cytotoxicity, intracellular interactions, and, notably, its effects on mesenchymal stem cells (MSCs). UGZ-1004 was characterized by lateral dimensions and layer counts consistent with ISO standards and demonstrated a high carbon purity of 0.08%. Cytotoxicity assessments revealed that UGZ-1004 is non-toxic to various cell lines, including 3T3 fibroblasts, VERO kidney epithelial cells, BV-2 microglia, and MSCs, in accordance with ISO 10993-5:2020/2023 guidelines. The study focused on MSCs and revealed that UGZ-1004 supports their gene expression alterations related to self-renewal and proliferation. MSCs exposed to UGZ-1004 maintained their characteristic surface markers. Importantly, UGZ-1004 promoted significant upregulation of genes crucial for cell cycle regulation and DNA repair, such as CDK1, CDK2, and MDM2. This gene expression profile suggests that UGZ-1004 can enhance MSC self-renewal capabilities, ensuring robust cellular function and longevity. Moreover, UGZ-1004 exposure led to the downregulation of genes associated with tumor development, including CCND1 and TFDP1, mitigating potential tumorigenic risks. These findings underscore the potential of UGZ-1004 to not only bolster MSC proliferation but also enhance their self-renewal processes, which are critical for effective regenerative therapies. The study highlights the need for continued research into the long-term impacts of graphene nanoplatelets and their application in MSC-based regenerative medicine.

Cucurbitacin B Inhibits the Proliferation of WPMY-1 Cells and HPRF Cells via the p53/MDM2 Axis

Modern research has shown that Cucurbitacin B (Cu B) possesses various biological activities such as liver protection, anti-inflammatory, and anti-tumor effects. However, the majority of research has primarily concentrated on its hepatoprotective effects, with limited attention devoted to exploring its potential impact on the prostate. Our research indicates that Cu B effectively inhibits the proliferation of human prostate stromal cells (WPMY-1) and fibroblasts (HPRF), while triggering apoptosis in prostate cells. When treated with 100 nM Cu B, the apoptosis rates of WPMY-1 and HPRF cells reached 51.73 ± 5.38% and 26.83 ± 0.40%, respectively. In addition, the cell cycle assay showed that Cu B had a G2/M phase cycle arrest effect on WPMY-1 cells. Based on RNA-sequencing analysis, Cu B might inhibit prostate cell proliferation via the p53 signaling pathway. Subsequently, the related gene and protein expression levels were measured using quantitative real-time PCR (RT-qPCR), immunocytochemistry (ICC), and enzyme-linked immunosorbent assays (ELISA). Our results mirrored the regulation of tumor protein p53 (TP53), mouse double minute-2 (MDM2), cyclin D1 (CCND1), and thrombospondin 1 (THBS1) in Cu B-induced prostate cell apoptosis. Altogether, Cu B may inhibit prostate cell proliferation and correlate to the modulation of the p53/MDM2 signaling cascade.

The diel disconnect between cell growth and division in Aureococcus is interrupted by giant virus infection

Viruses of eukaryotic algae have become an important research focus due to their role(s) in nutrient cycling and top-down control of algal blooms. Omics-based studies have identified a boon of genomic and transcriptional potential among the Nucleocytoviricota, a phylum of large dsDNA viruses which have been shown to infect algal and non-algal eukaryotes. However, little is still understood regarding the infection cycle of these viruses, particularly in how they take over a metabolically active host and convert it into a virocell state. Of particular interest are the roles light and the diel cycle in virocell development. Yet despite such a large proportion of Nucleocytoviricota infecting phototrophs, little work has been done to tie infection dynamics to the presence, and absence, of light. Here, we examine the role of the diel cycle on the physiological and transcriptional state of the pelagophyte Aureococcus anophagefferens while undergoing infection by Kratosvirus quantuckense strain AaV. Our observations demonstrate how infection by the virus interrupts the diel growth and division of this cell strain, and that infection further complicates the system by enhancing export of cell biomass.

mTOR and SGLT-2 Inhibitors: Their Synergistic Effect on Age-Related Processes

The aging process contributes significantly to the onset of chronic diseases, which are the primary causes of global mortality, morbidity, and healthcare costs. Numerous studies have shown that the removal of senescent cells from tissues extends lifespan and reduces the occurrence of age-related diseases. Consequently, there is growing momentum in the development of drugs targeting these cells. Among them, mTOR and SGLT-2 inhibitors have garnered attention due to their diverse effects: mTOR inhibitors regulate cellular growth, metabolism, and immune responses, while SGLT-2 inhibitors regulate glucose reabsorption in the kidneys, resulting in various beneficial metabolic effects. Importantly, these drugs may act synergistically by influencing senescence processes and pathways. Although direct studies on the combined effects of mTOR inhibition and SGLT-2 inhibition on age-related processes are limited, this review aims to highlight the potential synergistic benefits of these drugs in targeting senescence.

Chemotherapeutic Potential of Chlorambucil-Platinum(IV) Prodrugs against Cisplatin-Resistant Colorectal Cancer Cells

Chlorambucil-platinum(IV) prodrugs exhibit multi-mechanistic chemotherapeutic activity with promising anticancer potential. The platinum(II) precursors of the prodrugs have been previously found to induce changes in the microtubule cytoskeleton, specifically actin and tubulin of HT29 colon cells, while chlorambucil alkylates the DNA. These prodrugs demonstrate significant anticancer activity in 2D cell and 3D spheroid viability assays. A notable production of reactive oxygen species has been observed in HT29 cells 72 h post treatment with prodrugs of this type, while the mitochondrial membrane potential was substantially reduced. The cellular uptake of the chlorambucil-platinum(IV) prodrugs, assessed by ICP-MS, confirmed that active transport was the primary uptake mechanism, with platinum localisation identified primarily in the cytoskeletal fraction. Apoptosis and necrosis were observed at 72 h of treatment as demonstrated by Annexin V-FITC/PI assay using flow cytometry. Immunofluorescence measured via confocal microscopy showed significant changes in actin and tubulin intensity and in architecture. Western blot analysis of intrinsic and extrinsic pathway apoptotic markers, microtubule cytoskeleton markers, cell proliferation markers, as well as autophagy markers were studied post 72 h of treatment. The proteomic profile was also studied with a total of 1859 HT29 proteins quantified by mass spectroscopy, with several dysregulated proteins. Network analysis revealed dysregulation in transcription, MAPK markers, microtubule-associated proteins and mitochondrial transport dysfunction. This study confirms that chlorambucil-platinum(IV) prodrugs are candidates with promising anticancer potential that act as multi-mechanistic chemotherapeutics.

Insights into the Interaction Mechanisms of Peptide and Non-Peptide Inhibitors with MDM2 Using Gaussian-Accelerated Molecular Dynamics Simulations and Deep Learning

Inhibiting MDM2-p53 interaction is considered an efficient mode of cancer treatment. In our current study, Gaussian-accelerated molecular dynamics (GaMD), deep learning (DL), and binding free energy calculations were combined together to probe the binding mechanism of non-peptide inhibitors K23 and 0Y7 and peptide ones PDI6W and PDI to MDM2. The GaMD trajectory-based DL approach successfully identified significant functional domains, predominantly located at the helixes α2 and α2', as well as the β-strands and loops between α2 and α2'. The post-processing analysis of the GaMD simulations indicated that inhibitor binding highly influences the structural flexibility and collective motions of MDM2. Calculations of molecular mechanics-generalized Born surface area (MM-GBSA) and solvated interaction energy (SIE) not only suggest that the ranking of the calculated binding free energies is in agreement with that of the experimental results, but also verify that van der Walls interactions are the primary forces responsible for inhibitor-MDM2 binding. Our findings also indicate that peptide inhibitors yield more interaction contacts with MDM2 compared to non-peptide inhibitors. Principal component analysis (PCA) and free energy landscape (FEL) analysis indicated that the piperidinone inhibitor 0Y7 shows the most pronounced impact on the free energy profiles of MDM2, with the piperidinone inhibitor demonstrating higher fluctuation amplitudes along primary eigenvectors. The hot spots of MDM2 revealed by residue-based free energy estimation provide target sites for drug design toward MDM2. This study is expected to provide useful theoretical aid for the development of selective inhibitors of MDM2 family members.

Anticancer Effect of PtIIPHENSS, PtII5MESS, PtII56MESS and Their Platinum(IV)-Dihydroxy Derivatives against Triple-Negative Breast Cancer and Cisplatin-Resistant Colorectal Cancer

Development of resistance to cisplatin, oxaliplatin and carboplatin remains a challenge for their use as chemotherapies, particularly in breast and colorectal cancer. Here, we compare the anticancer effect of novel complexes [Pt(1,10-phenanthroline)(1S,2S-diaminocyclohexane)](NO3)2 (PtIIPHENSS), [Pt(5-methyl-1,10-phenanthroline)(1S,2S-diaminocyclohexane)](NO3)2 (PtII5MESS) and [Pt(5,6-dimethyl-1,10-phenanthroline)(1S,2S-diaminocyclohexane)](NO3)2 (PtII56MESS) and their platinum(IV)-dihydroxy derivatives with cisplatin. Complexes are greater than 11-fold more potent than cisplatin in both 2D and 3D cell line cultures with increased selectivity for cancer cells over genetically stable cells. ICP-MS studies showed cellular uptake occurred through an active transport mechanism with considerably altered platinum concentrations found in the cytoskeleton across all complexes after 24 h. Significant reactive oxygen species generation was observed, with reduced mitochondrial membrane potential at 72 h of treatment. Late apoptosis/necrosis was shown by Annexin V-FITC/PI flow cytometry assay, accompanied by increased sub-G0/G1 cells compared with untreated cells. An increase in S and G2+M cells was seen with all complexes. Treatment resulted in significant changes in actin and tubulin staining. Intrinsic and extrinsic apoptosis markers, MAPK/ERK and PI3K/AKT activation markers, together with autophagy markers showed significant activation of these pathways by Western blot. The proteomic profile investigated post-72 h of treatment identified 1597 MDA-MB-231 and 1859 HT29 proteins quantified by mass spectroscopy, with several differentially expressed proteins relative to no treatment. GO enrichment analysis revealed a statistically significant enrichment of RNA/DNA-associated proteins in both the cell lines and specific additional processes for individual drugs. This study shows that these novel agents function as multi-mechanistic chemotherapeutics, offering promising anticancer potential, and thereby supporting further research into their application as cancer therapeutics.

Ubiquitin recruiting chimera: more than just a PROTAC

Ubiquitinylation of protein substrates results in various but distinct biological consequences, among which ubiquitin-mediated degradation is most well studied for its therapeutic application. Accordingly, artificially targeted ubiquitin-dependent degradation of various proteins has evolved into the therapeutically relevant PROTAC technology. This tethered ubiquitinylation of various targets coupled with a broad assortment of modifying E3 ubiquitin ligases has been made possible by rational design of bi-specific chimeric molecules that bring these proteins in proximity. However, forced ubiquitinylation inflicted by the binary warheads of a chimeric PROTAC molecule should not necessarily result in protein degradation but can be used to modulate other cellular functions. In this respect it should be noted that the ubiquitinylation of a diverse set of proteins is known to control their transport, transcriptional activity, and protein-protein interactions. This review provides examples of potential PROTAC usage based on non-degradable ubiquitinylation.

LncRNA MALAT1 and Ischemic Stroke: Pathogenesis and Opportunities

Ischemic stroke (IS) stands as a prominent cause of mortality and long-term disability around the world. It arises primarily from a disruption in cerebral blood flow, inflicting severe neural injuries. Hence, there is a pressing need to comprehensively understand the intricate mechanisms underlying IS and identify novel therapeutic targets. Recently, long noncoding RNAs (lncRNAs) have emerged as a novel class of regulatory molecules with the potential to attenuate pathogenic mechanisms following IS. Among these lncRNAs, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) has been extensively studied due to its involvement in the pathophysiological processes of IS. In this review, we provide an in-depth analysis of the essential role of MALAT1 in the development and progression of both pathogenic and protective mechanisms following IS. These mechanisms include oxidative stress, neuroinflammation, cell death signaling, blood brain barrier dysfunction, and angiogenesis. Furthermore, we summarize the impact of MALAT1 on the susceptibility and severity of IS. This review highlights the potential risks associated with the therapeutic use of MALAT1 for IS, which are attributable to the stimulatory action of MALAT1 on ischemia/reperfusion injury. Ultimately, this review sheds light on the potential molecular mechanisms and associated signaling pathways underlying MALAT1 expression post-IS, with the aim of uncovering potential therapeutic targets.

Targeting Hdm2 and Hdm4 in Anticancer Drug Discovery: Implications for Checkpoint Inhibitor Immunotherapy

Hdm2 and Hdm4 are structural homologs that regulate the tumor suppressor protein, p53. Since some tumors express wild-type p53, Hdm2 and Hdm4 are plausible targets for anticancer drugs, especially in tumors that express wild-type p53. Hdm4 can enhance and antagonize the activity of Tp53, thereby playing a critical role in the regulation of p53's activity and stability. Moreover, Hdm2 and Hdm4 are overexpressed in many cancers, some expressing wild-type Tp53. Due to experimental evidence suggesting that the activation of wild-type Tp53 can augment the antitumor activity by some checkpoint inhibitors, drugs targeting Hdm2 and Hdm4 may be strong candidates for combining with checkpoint inhibitor immunotherapy. However, other evidence suggests that the overexpression of Hdm2 and Hdm4 may indicate poor response to immune checkpoint inhibitors. These findings require careful examination and scrutiny. In this article, a comprehensive analysis of the Hdm2/Hdm4 partnership will be conducted. Furthermore, this article will address the current progress of drug development regarding molecules that target the Hdm2/Hdm4/Tp53 partnership.

p53/MDM2 signaling pathway in aging, senescence and tumorigenesis

A wealth of evidence has emerged that there is an association between aging, senescence and tumorigenesis. Senescence, a biological process by which cells cease to divide and enter a status of permanent cell cycle arrest, contributes to aging and aging-related diseases, including cancer. Aging populations have the higher incidence of cancer due to a lifetime of exposure to cancer-causing agents, reduction of repairing DNA damage, accumulated genetic mutations, and decreased immune system efficiency. Cancer patients undergoing cytotoxic therapies, such as chemotherapy and radiotherapy, accelerate aging. There is growing evidence that p53/MDM2 (murine double minute 2) axis is critically involved in regulation of aging, senescence and oncogenesis. Therefore, in this review, we describe the functions and mechanisms of p53/MDM2-mediated senescence, aging and carcinogenesis. Moreover, we highlight the small molecular inhibitors, natural compounds and PROTACs (proteolysis targeting chimeras) that target p53/MDM2 pathway to influence aging and cancer. Modification of p53/MDM2 could be a potential strategy for treatment of aging, senescence and tumorigenesis.

Unveiling therapeutic prospects: targeting MDM-2 in non-muscle invasive bladder cancer

Non-muscle invasive bladder cancer (NMIBC) is considered one of the most costly malignancies, requiring significant surgical and therapeutic measures. However, progression and non-responsiveness to immunotherapy are common outcomes of treatment. In this study, we conducted comparative transcriptomic analysis of non-responders from two distinct populations (Asian and American) and identified six common genes associated with disease prognosis. Among these genes, MDM-2 is a major oncogenic protein linked to seven different types of cancers, as it is involved in the degradation of the tumor suppressor protein p53. To address this, we explored novel therapeutic drugs to block the binding of p53 and MDM-2 using a targeted molecular docking approach. High-throughput screening of 2500 drugs from the FDA-approved drug database led to the identification of three drug compounds: Mol-126, Mol-679, and Mol-768. Subsequently, we evaluated the structural stability and binding of these drugs for the targeted inhibition of the MDM-2 active site (hydrophobic cleft) using molecular dynamics simulations. Analysis of five trajectories, including RMSD, RMSF, hydrogen bond, radius of gyration, coulomb short-range electrostatic spectra, and free binding energy, confirmed that Mol-126 exhibited the highest structural stability compared to the reference drug (Alrizomadlin). Notably, Mol-126 is a derivative of 3-phenoxypropionic acid, which shows promise for the development of alternative therapeutic treatments for non-responsive bladder cancer patients.

Role of circular RNAs in lung cancer

Lung cancer remains a global public health concern with significant research focus on developing better diagnosis/prognosis biomarkers and therapeutical targets. Circular RNAs (circRNAs) are a type of single-stranded RNA molecules that covalently closed and have ubiquitous expression. These molecules have been implicated in a variety of disease mechanisms, including lung cancer, as they exhibit oncogenic or tumor suppressor characteristics. Recent research has shown an important role that circRNAs play at different stages of lung cancer, particularly in lung adenocarcinoma. In this review, we summarize the latest research on circRNAs and their roles within lung cancer diagnosis, as well as on disease mechanisms. We also discuss the knowledge gaps on these topics and possible future research directions.

The Antiproliferative and Proapoptotic Effects of Cucurbitacin B on BPH-1 Cells via the p53/MDM2 Axis

Cucurbitacin B (Cu B), a triterpenoid compound, has anti-inflammatory and antioxidant activities. Most studies only focus on the hepatoprotective activity of Cu B, and little effort has been geared toward exploring the effect of Cu B on the prostate. Our study identified that Cu B inhibited the proliferation of the benign prostatic hyperplasia epithelial cell line (BPH-1). At the molecular level, Cu B upregulated MDM2 and thrombospondin 1 (THBS1) mRNA levels. Immunocytochemistry results revealed that the protein expressions of p53 and MDM2 were upregulated in BPH-1 cells. Furthermore, Cu B upregulated THBS1 expression and downregulated COX-2 expression in the BPH-1 cell supernatant. Altogether, Cu B may inhibit prostate cell proliferation by activating the p53/MDM2 signaling cascade and downregulating the COX-2 expression.

Moringa oleifera and Autophagy: Evidence from In Vitro Studies on Chaperone-Mediated Autophagy in HepG2 Cancer Cells

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer in Sub-Saharan African countries, including South Africa (SA). Given the limitations in current HCC therapeutics, there is an increasing need for alternative adjuvant therapeutic options. As such, several cell survival mechanisms, such as autophagy, have been identified as potential adjuvant therapeutic targets in HCC treatment. Of the three most established autophagic pathways, the upregulation of chaperone-mediated autophagy (CMA) has been extensively described in various cancer cells, including HCC cells. CMA promotes tumor growth and chemotherapeutic drug resistance, thus contributing to HCC tumorigenesis. Therefore, the modulation of CMA serves as a promising adjuvant target for current HCC therapeutic strategies. Phytochemical extracts found in the medicinal plant, Moringa oleifera (MO), have been shown to induce apoptosis in numerous cancer cells, including HCC. MO leaves have the greatest abundance of phytochemicals displaying anticancer potential. However, the potential interaction between the pro-apoptotic effects of MO aqueous leaf extract and the survival-promoting role of CMA in an in vitro model of HCC remains unclear. This review aims to summarize the latest findings on the role of CMA, and MO in the progression of HCC.

ZNF500 abolishes breast cancer proliferation and sensitizes chemotherapy by stabilizing P53 via competing with MDM2

Zinc finger protein 500 (ZNF500) has an unknown expression pattern and biological function in human tissues. Our study revealed that the ZNF500 mRNA and protein levels were higher in breast cancer tissues than those in their normal counterparts. However, ZNF500 expression was negatively correlated with advanced TNM stage (p = 0.018), positive lymph node metastasis (p = 0.014), and a poor prognosis (p < 0.001). ZNF500 overexpression abolished in vivo and in vitro breast cancer cell proliferation by activating the p53-p21-E2F4 signaling axis and directly interacting with p53 via its C2H2 domain. This may prevent ubiquitination of p53 in a manner that is competitive to MDM2, thus stabilizing p53. When ZNF500-∆C2H2 was overexpressed, the suppressed proliferation of breast cancer cells was neutralized in vitro and in vivo. In human breast cancer tissues, ZNF500 expression was positively correlated with p53 (p = 0.022) and E2F4 (p = 0.004) expression. ZNF500 expression was significantly lower in patients with Miller/Payne Grade 1-2 than in those with Miller/Payne Grade 3-5 (p = 0.012). ZNF500 suppresses breast cancer cell proliferation and sensitizes cells to chemotherapy.

Synthesis and biological evaluation of dual MDM2/XIAP inhibitors based on the tetrahydroquinoline scaffold

Overexpression of both human murine double minute 2 (MDM2) and X-linked inhibitor of apoptosis protein (XIAP) is detected in tumor cells from several cancer types, including childhood acute leukemia lymphoma (ALL), neuroblastoma (NB), and prostate cancer, and is associated with disease progression and treatment resistance. In this report, we described the design and syntheses of a series of dual MDM2/XIAP inhibitors based on the tetrahydroquinoline scaffold from our previously reported lead compound JW-2-107 and tested their cytotoxicity in a panel of human cancer cell lines. The best compound identified in this study is compound 3e. Western blot analyses demonstrated that treatments with 3e decreased MDM2 and XIAP protein levels and increased expression of p53, resulting in cancer cell growth inhibition and cell death. Furthermore, compound 3e effectively inhibited tumor growth in vivo when tested using a human 22Rv1 prostate cancer xenograft model. Collectively, results in this study strongly suggest that the tetrahydroquinoline scaffold, represented by 3e and our earlier lead compound JW-2-107, has abilities to dual target MDM2 and XIAP and is promising for further preclinical development.

Effect of Smilax spp. and Phellinus linteus combination on cytotoxicity and cell proliferation of breast cancer cells

BACKGROUND

Although the prevalence of breast cancer (BC) has been reduced in recent years, proficient therapeutic regimens should be further investigated with the aim of further reducing the mortality rate. To obtain more effective treatment, the present study aimed to observe the effects of PL synergistically combined with Smilax corbularia and S. glabra extracts (PSS) on BC cell lines, MCF7, T47D, MDA-MB-231, and MDA-MB-468.

METHODS

The half-maximal inhibition (IC₅₀) concentrations of PSS and PL were determined in a dose- and time-dependent manner using MTT assay. The activity of PSS and PL on anti-BC proliferation was evaluated using BrdU assay, and colony formation assay. Moreover, cell cycle analysis and apoptosis induction as a result of PSS and PL exposure were investigated using propidium iodide (PI) staining and co-staining of annexin V DY634 and PI combined flow cytometric analysis, respectively. Finally, changes in the mRNA expression of genes involved in proliferative and apoptotic pathways (MKI67, HER2, EGFR, MDM2, TNFα, PI3KCA, KRAS, BAX, and CASP8) were explored using RT-qPCR following PSS and PL treatment.

RESULTS

The PSS and PL extracts exhibited significant potential in BC cytotoxicity which were in were in dose- and time-dependent response. This inhibition of cell growth was due to the suppression of cell proliferation, the cell cycle arrest, and the induction of apoptosis. Additionally, an investigation of the underlying molecular mechanism revealed that PSS and PL are involved in downregulation of the MKI67, HER2, EGFR, MDM2, TNFα, and PI3KCA expression.

CONCLUSIONS

This present study has suggested that PSS and PL possess anti-BC proliferative activity mediated via the downregulation of genes participating in the relevant pathways. PSS or PL may be combined with other agents to alleviate the adverse side effects resulted from conventional chemotherapeutic drugs.

Effect of Borrelia burgdorferi on the Expression of miRNAs in Breast Cancer and Normal Mammary Epithelial Cells

Breast cancer is one of the leading causes of death in women worldwide. Recent studies have demonstrated that inflammation due to infections with microorganisms could play a role in breast cancer development. One of the known human pathogens, Borrelia burgdorferi, the causative agent of Lyme disease, has been shown to be present in various types of breast cancer and is associated with poor prognosis. We reported that B. burgdorferi can invade breast cancer cells and affect their tumorigenic phenotype. To better understand the genome-wide genetic changes caused by B. burgdorferi, we evaluated the microRNA (miRNA or miR) expression profiles of two triple-negative breast cancer cell lines and one non-tumorigenic mammary cell line before and after B. burgdorferi infection. Using a cancer-specific miRNA panel, four miRNAs (miR-206, 214-3p, 16-5p, and 20b-5p) were identified as potential markers for Borrelia-induced changes, and the results were confirmed by quantitative real-time reverse transcription (qRT-PCR). Among those miRNAs, miR-206 and 214 were the most significantly upregulated miRNAs. The cellular impact of miR-206 and 214 was evaluated using DIANA software to identify related molecular pathways and genes. Analyses showed that the cell cycle, checkpoints, DNA damage-repair, proto-oncogenes, and cancer-related signaling pathways are mostly affected by B. burgdorferi infection. Based on this information, we have identified potential miRNAs which could be further evaluated as biomarkers for tumorigenesis caused by pathogens in breast cancer cells.

MDM2 for the practicing pathologist: a primer

The mouse double minute 2 (MDM2) gene is located on the long arm of chromosome 12 and is the primary negative regulator of p53. The MDM2 gene encodes an E3 ubiquitin-protein ligase that mediates the ubiquitination of p53, leading to its degradation. MDM2 enhances tumour formation by inactivating the p53 tumour suppressor protein. The MDM2 gene also has many p53-independent functions. Alterations of MDM2 may occur through various mechanisms and contribute to the pathogenesis of many human tumours and some non-neoplastic diseases. Detection of MDM2 amplification is used in the clinical practice setting to help diagnose multiple tumour types, including lipomatous neoplasms, low-grade osteosarcomas and intimal sarcoma, among others. It is generally a marker of adverse prognosis, and MDM2-targeted therapies are currently in clinical trials. This article provides a concise overview of the MDM2 gene and discusses practical diagnostic applications pertaining to human tumour biology.

A Novel Defined Pyroptosis-Related Gene Signature for Predicting the Prognosis of Endometrial Cancer

Endometrial carcinoma (EC) is the second major female genital malignancy. Genetic signatures may be an improved choice to predict the prognosis of EC patients. The relationship between pyroptosis and tumours has attracted much attention in recent years. Here, we constructed a new pyroptosis-related gene (PRG) signature for predicting the prognosis of EC. In this study, gene data and clinical information of EC patients were obtained from The Cancer Genome Atlas (TCGA). Following the identification of PRGs correlated with EC prognosis, we further investigate the bioinformatics functions of these PRGs by univariate Cox regression analysis and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Then, we used the least absolute contraction and selection operator (LASSO) regression and multiple Cox regression analysis to construct a new PRG signature that contains seven PRGs (NFKB1, EEF2K, CTSV, MDM2, GZMB, PANX1, and PTEN) and performed the Kaplan-Meier (K-M) analysis, receiver operating characteristic curve (ROC) analysis, and principal component analysis (PCA) to evaluate the prognostic value of our novel PRG signature. Finally, we assessed the correlations between pyroptosis and immune cells/checkpoints through the CIBERSORT tool and single-sample gene set enrichment analysis (ssGSEA). The result suggested that our signature was powerful in predicting EC prognosis and may play a part in assessing response to immunotherapy in EC patients. In conclusion, our study established a novel PRG signature for EC, which can be used as an effective prognostic marker in clinical practice in the future.

The E3 Ligases in Cervical Cancer and Endometrial Cancer

Endometrial (EC) and cervical (CC) cancers are the most prevalent malignancies of the female reproductive system. There is a global trend towards increasing incidence and mortality, with a decreasing age trend. E3 ligases label substrates with ubiquitin to regulate their activity and stability and are involved in various cellular functions. Studies have confirmed abnormal expression or mutations of E3 ligases in EC and CC, indicating their vital roles in the occurrence and progression of EC and CC. This paper provides an overview of the E3 ligases implicated in EC and CC and discusses their underlying mechanism. In addition, this review provides research advances in the target of ubiquitination processes in EC and CC.

Circular RNA Controls Tumor Occurrence and Development via Cell Cycle Regulation

Circular RNAs (circRNAs) participate in the occurrence and development of various diseases through different mechanisms, such as by acting as a microRNA (miRNA) sponge, interacting with RNA-binding proteins, and regulating gene transcription and protein translation. For example, the abnormal expression of specific circRNAs in tumor cells can alter key regulatory factors and the cell cycle network, resulting in cell cycle disorders and the development and metastasis of tumors. Here, we summarize the mechanisms involved in the circRNA-mediated processes that lead to uncontrolled cell cycle and tumor cell proliferation. Extensive studies investigating the abnormal expression of circRNAs in different cancer types have been conducted. The unique characteristics of circRNAs and their ability to regulate the cell cycle through diverse mechanisms is extremely valuable in tumor diagnosis, treatment, and prognosis. Our review may assist in further understanding the circRNA-mediated regulation of the cell cycle in tumors and provide insights for research on circRNA-based therapeutic strategies and biological diagnosis for cancer.

The roles of E3 ligases in Hepatocellular carcinoma

Hepatocarcinogenesis is a complex multistep biological process involving genetic and epigenetic alterations that are accompanied by activation of oncoproteins and inactivation of tumor suppressors, which in turn results in Hepatocellular carcinoma (HCC), one of the common tumors with high morbidity and mortality worldwide. The ubiquitin-proteasome system (UPS) is the key to protein degradation and regulation of physiological and pathological processes, and E3 ligases are key enzymes in the UPS that contain a variety of subfamily proteins involved in the regulation of some common signal pathways in HCC. There is growing evidence that many structural or functional dysfunctions of E3 are engaged in the development and progression of HCC. Herein, we review recent research advances in HCC-associated E3 ligases, describe their structure, classification, functional roles, and discuss some mechanisms of the abnormal activation or inactivation of the HCC-associated signal pathway due to the binding of E3 to known substrates. In addition, given the success of proteasome inhibitors in the treatment of malignant cancers, we characterize the current knowledge and future prospects for targeted therapies against aberrant E3 in HCC.

Context-dependent activation of p53 target genes and induction of apoptosis by actinomycin D in aerodigestive tract cancers

Actinomycin D (ActD) was the first anticancer antibiotic approved for the management of human cancers. However, the notorious toxicity profile limits its widespread application in cancers, including cancers of the aerodigestive tract. Recent studies show that combining low-dose ActD with existing chemotherapies could potentially protect normal cells from the toxicity of chemotherapy drugs through p53 activation (cyclotherapy). An understanding of ActD's effect on p53 signaling is critical for the meaningful application of ActD in cyclotherapy-based combinations. This study evaluated the anti-tumor efficacy and mechanism of action of ActD in aerodigestive tract cancers. We found that ActD strongly inhibited the growth of a panel of aerodigestive tract cancer cell lines and induced efficient apoptosis, although the sensitivity varies among cell lines. The IC₅₀ values of ActD spanned between 0.021 and 2.96 nM. Mechanistic studies revealed that ActD increased the expression of total and phosphorylated p53 (ser15) in a time- and dose-dependent manner. Moreover, ActD-induced apoptosis is dependent on p53 in cells expressing wild-type p53 and that ActD induced context-dependent differential expression of downstream targets p21 and PUMA without significant effects on p27. In the final analysis, this study revealed that p53-p21 is the predominant pathway activated by low-dose ActD, supporting further development of ActD in cyclotherapy.

Association between ТР53, MDM2 and NQO1 gene polymorphisms and viral load among women with human papillomavirus

The risk of cervical cancer is caused by persistent human papillomavirus (HPV) infection. Cervical cancer is the most frequent cancer among women. Our purpose was to investigate the association between TP53 215C>G (Pro72Arg), MDM2 -410T>G, and NQO1 609C>T gene polymorphisms with a high HPV load and the inf luence of gene-gene interactions on prolonged HPV infection. Eighty-nine women with a high HPV viral load and 114 healthy women were involved in a case–control study. Genotyping for TP53 215C>G (Pro72Arg) and MDM2 -410T>G SNPs was carried out by allele-specif ic PCR and genotyping for NQO1 609C>T was performed by a TaqMan assay. Quantitative analysis of HPV DNA was performed by AmpliSens® HPV HCR screen-titer-FRT test system. Gene-gene interactions were analyzed using the multifactor dimensionality reduction (MDR) method. The study of separate SNPs of MDM2 -410T>G and NQO1 609C>T genes did not reveal any statistically signif icant difference in genotype and allele frequencies among women within the two groups. The frequency of the 215G (72Arg) allele and 215GG (72Arg/ Arg) genotype of the TP53 gene was signif icantly higher in the case group than in the control group (OR = 1.74, 95 % CI = 1.10–2.73; p = 0.02 and OR = 1.97, 95 % CI = 1.13–3.46; p = 0.04, respectively). MDR analysis showed the signif icance of intergenic interactions of the three studied loci TP53 (rs1042522) – MDM2 (rs2279744) – NQO1 (rs1800566) for the formation of a high HPV load (OR = 3.05, 95 % CI = 1.73–5.46; p = 0.0001).

P53: Stability from the Ubiquitin-Proteasome System and Specific 26S Proteasome Inhibitors

Protein p53 is degraded by the 26S proteasome, a protein complex that breaks down cellular proteins. Degradation begins with activation of the protein ubiquitin (Ub) by the ubiquitin-activating E1 enzymes, ubiquitin-conjugating E2 enzymes, and ubiquitin E3 ligases, linking Ub or the polyubiquitin chain to p53 and marking it for degradation by the 26S proteasome. E3 ubiquitin ligases participate in this process and regulate p53 stability. There are compounds that inhibit the 26S proteasome and interfere at the p53 level, and some of these inhibitors are used to treat cancer and other diseases and can stabilize tumor suppressor proteins through the p53 pathway. This review discusses how the ubiquitin-proteasome system, p53, and these compounds are related.

Prediction of Genes Involved in Lung Cancer with a Systems Biology Approach Based on Comprehensive Gene Information

Over the past few years, hundreds of genes have been reported in relation to lung cancer. Systems biology studies can help validate this association and find the most valid genes to use in the diagnosis and treatment. We reviewed the candidate genes for lung cancer in 120 published articles from September 1, 1993, to September 1, 2020. We obtained 134 up- and 36 downregulated genes for lung cancer in this article. The genes extracted from the articles were imported to Search Tool for the Retrieval of Interacting genes/proteins (STRING) to construct the protein-protein interaction (PPI) Network and pathway enrichment. GO ontology and Reactome databases were used for describing the genes, average length of survival, and constructing networks. Then, the ClusterONE plugin of Cytoscape software was used to analyze and cluster networks. Hubs and bottleneck nodes were defined based on their degree and betweenness. Common genes between the ClusterONE plugin and network analysis consisted of seven genes (BRCA1-TP53-CASP3-PLK1-VEGFA-MDM2-CCNB1 and PLK1), and two genes (PLK1 and TYMS) were selected as survival factors. Our drug-gene network showed that CASP3, BRCA1, TP53, VEGFA, and MDM2 are common genes that are involved in this network. Also, among the drugs recognized in the drug-gene network, five drugs such as paclitaxel, oxaliplatin, carboplatin, irinotecan, and cisplatin were examined in different studies. It seems that these seven genes, with further studies and confirmatory tests, could be potential markers for lung cancer, especially PLK1 that has a significant effect on the survival of patients. We provide the novel genes into the pathogenesis of lung cancer, and we introduced new potential biomarkers for this malignancy.

Association of Murine Double Minute 2 polymorphisms with gastric cancer: A systematic review with meta-analysis

Gastric cancer (GC) is the 5th most common type of cancer, with the 3rd highest mortality rate worldwide in both sexes. Murine double minute 2 (MDM2) protein is the major negative regulator of p53, and genetic polymorphisms in this gene have shown to be associated with several types of cancer. In the present study, a literature search was performed using PubMed and Scopus with the following key word combinations 'gastric cancer AND polymorphism AND MDM2'. Studies were carefully revised according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify eligible studies that matched the inclusion criteria. Statistical analysis was performed to assess the association between the different genetic polymorphisms and GC risk, by calculating the odds ratios (OR) and the confidence intervals (CI), with a 5% level of significance. A total of 11 manuscripts studied MDM2 polymorphisms in GC: rs937283 (n=1), rs3730485 (n=1) and rs2279744 (n=9). Both the rs937283 and rs3730485 reports showed an association with GC; however, there was only one study on each of these polymorphisms in the literature. A meta-analysis was performed for the rs2279744 polymorphism, of which studies showed a positive association between the G allele and risk of GC, either in the dominant model (OR=1.46; 95% CI 1.21-1.75; P<0.001) or recessive model (OR 1.65; 95% CI 1.45-1.87; P<0.001). In conclusion, genetic polymorphisms in MDM2 seemed to be associated with an increased risk of GC development, nevertheless, the number of studies were relatively low and the studied populations were primarily Chinese. The present meta-analysis emphasizes the need for additional studies in other populations to corroborate the association of these polymorphisms with GC.

PROTAC: An Effective Targeted Protein Degradation Strategy for Cancer Therapy

Proteolysis targeting chimeric (PROTAC) technology is an effective endogenous protein degradation tool developed in recent years that can ubiquitinate the target proteins through the ubiquitin-proteasome system (UPS) to achieve an effect on tumor growth. A number of literature studies on PROTAC technology have proved an insight into the feasibility of PROTAC technology to degrade target proteins. Additionally, the first oral PROTACs (ARV-110 and ARV-471) have shown encouraging results in clinical trials for prostate and breast cancer treatment, which inspires a greater enthusiasm for PROTAC research. Here we focus on the structures and mechanisms of PROTACs and describe several classes of effective PROTAC degraders based on E3 ligases.

Development and structural characterisation of human scFv targeting MDM2 spliced variant MDM215kDa

The murine double minute 2 (MDM2) protein is a major negative regulator of the tumour suppressor protein p53. Under normal conditions, MDM2 constantly binds to p53 transactivation domain and/or ubiquinates p53 via its role as E3 ubiquitin ligase to promote p53 degradation as well as nuclear export to maintain p53 levels in cells. Meanwhile, amplification of MDM2 and appearance of MDM2 spliced variants occur in many tumours and normal tissues making it a prognostic indicator for human cancers. The mutation or deletion of p53 protein in half of human cancers inactivates its tumour suppressor activity. However, cancers with wild type p53 have its function effectively inhibited through direct interaction with MDM2 oncoprotein. Here, we described the construction of a MDM2 spliced variant (rMDM2^15kDa) consisting of SWIB/MDM2 domain and its central region for antibody generation. Biopanning with a human naïve scFv library generated four scFv clones specific to rMDM2^15kDa. Additionally, the selected scFv clones were able to bind to the recombinant full length MDM2 (rMDM2-FL). Computational prediction showed that the selected scFv clones potentially bind to exon 7-8 of MDM2 while leaving the MDM2/SWIB domain free for p53 interaction. The developed antibodies exhibit good specificity can be further investigated for downstream biomedical and research applications.

Studying Homo-oligomerization and Hetero-oligomerization of MDMX and MDM2 Proteins in Single Living Cells by Using In Situ Fluorescence Correlation Spectroscopy

Protein oligomerization plays a very important role in many physiological processes. p53 acts as a key tumor suppressor by regulating cell cycle arrest, DNA repair, and apoptosis, and its antitumor activity is regulated by the hetero- and homo-oligomerization of MDMX and MDM2 proteins. So far, some traditional methods have been utilized to study the oligomerization of MDMX and MDM2 in vitro, but they have not clarified some controversial issues or whether the extracellular results can represent the intracellular results. Here, we put forward an in situ method for studying protein homo- and hetero-oligomerization in single living cells by using fluorescence correlation spectroscopy. In this study, MDMX and MDM2 were labeled with fluorescent proteins using lentiviral transfection. Autocorrelation spectroscopy and cross-correlation spectroscopy methods were used to study the oligomerization of MDMX and MDM2 in situ and the effect of regulation of MDMX oligomerization on p53-MDMX interactions in single living cells. We observed the homo- and hetero-oligomerization of MDMX and MDM2 in living cells. Meanwhile, the levels of the homo-oligomers of MDMX and MDM2 were increased due to the lack of hetero-oligomerization. Finally, the binding affinity of MDMX for p53 was improved with an increase in the level of MDMX hetero-oligomerization.

MDM2-dependent Sirt1 degradation is a prerequisite for Sirt6-mediated cell death in head and neck cancers

Sirt6 is involved in multiple biological processes, including aging, metabolism, and tumor suppression. Sirt1, another member of the sirtuin family, functionally overlaps with Sirt6, but its role in tumorigenesis is controversial. In this study, we focused on cell death in association with Sirt6/Sirt1 and reactive oxygen species (ROS) in head and neck squamous cell carcinomas (HNSCCs). Sirt6 induced cell death, as widely reported, but Sirt1 contributed to cell death only when it was suppressed by Sirt6 via regulation of MDM2. Sirt6 and Sirt6-mediated suppression of Sirt1 upregulated ROS, which further led to HNSCC cell death. These results provide insight into the molecular roles of Sirt6 and Sirt1 in tumorigenesis and could therefore contribute to the development of novel strategies to treat HNSCC.

New understanding of the interactions between three proteins sheds light on their role in either promoting or restricting the development of tumors called squamous cell carcinomas, which account for over 90% of all cancers in the head and neck. Researchers in South Korea led by Sang Yoon Kim and Seong Who Kim at the University of Ulsan, Seoul, investigated the role of the proteins Sirt6, Sirt1 and MDM2 in controlling the death of cancer cells caused by chemicals called reactive oxygen species (ROS). The effects of Sirt6 and Sirt1 combine to regulate ROS-induced cancer cell death. Sirt6 controls the activity of MDM2, stimulating ROS production. Sirt6 also influences MDM2 to suppress Sirt1 activity, thereby also promoting cancer cell death. Drugs affecting these three proteins could offer new approaches to anti-cancer therapy.

Associations of MDM2 and MDM4 Polymorphisms with Early-Stage Breast Cancer

Breast cancer is one of the most common cancers worldwide. Single nucleotide polymorphisms (SNPs) in MDM2 and MDM4 have been associated with various cancers. However, the influence on clinical characteristics of breast cancer has not been sufficiently investigated yet. Thus, this study aimed to investigate the relationship between SNPs in MDM2 (rs2279744, rs937283, rs937282) and MDM4 (rs1380576, rs4245739) and I-II stage breast cancer. For analysis, the genomic DNA was extracted from 100 unrelated women peripheral blood. Polymorphisms were analyzed with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. The study showed that MDM2 rs937283 and rs937282 were significantly associated with estrogen receptor status and human epidermal growth factor receptor 2 (HER2) status. SNPs rs1380576 and rs4245739, located in MDM4, were significantly associated with status of estrogen and progesterone receptors. Our findings suggest that rs937283 AG, rs937282 CG, rs1380576 CC, and rs4245739 AA genotypes were linked to hormonal receptor positive breast cancer and may be useful genetic markers for disease assessment.

Murine Double Minute 2 Gene (MDM2) rs937283A/G variant significantly increases the susceptibility to breast cancer in Saudi Women

Breast cancer is predominant causes of mortality in women worldwide. Genetic polymorphisms have a significant role in breast cancer aetiology. TP53 and its inhibitor the murine double minute 2 (MDM2) genes encode proteins that have crucial functions in the DNA damage response. The allelic variations within these genes could influence the susceptibility to breast cancer. MDM2 promotor polymorphism rs937283A/G has a role in susceptibility to cancer and modifies the promoter activity. In the present case-control study, the association of MDM2 rs937283A/G polymorphism and breast cancer susceptibility in Saudi women with samples of 137 breast cancer patients, and 98 healthy controls were explored. MDM2 gene polymorphism rs937283A/G was genotyped by polymerase chain reaction restriction fragment length polymorphism and confirmed by sequencing. The results revealed that rs937283A/G variant is significantly increases the risk of breast cancer in Saudi women (p-value = 0.0078). Moreover, rs937283A/G polymorphism was associated with high risk of breast cancer in estrogen positive breast cancer patients (p-value = 0.0088), progesterone positive breast cancer patients (p-value = 0.0043), human epidermal growth factor receptor 2 negative breast cancer patients (p-value = 0.0026), and triple negative breast cancer patients where (p-value = 0.0003). Positive association between increased breast cancer risk and rs937283 variant in premenopausal Saudi women, below 50 years of age, was demonstrated (p-value = 0.0023). Collectively, MDM2 rs937283A/G polymorphism could act as a possible biomarker for breast cancer susceptibility in Saudi women.

A case-control study on the SNP309T → G and 40-bp Del1518 of the MDM2 gene and a systematic review for MDM2 polymorphisms in the patients with breast cancer

OBJECTIVE

The current research was conducted to study the association between the SNP309 and del1518 polymorphisms with the breast cancer in the patients with the Kurdish ethnic background from western Iran. Also, a systematic review of the relevant case-control studies on the MDM2 polymorphisms in the patients with breast cancer was performed.

METHODOLOGY

Two mL of peripheral blood was taken from 100 patients with breast cancer and 100 healthy individuals. The frequencies of MDM2 SNP309 and del1518 genotypes and alleles were determined using the PCR-RFLP and PCR methods, respectively.

RESULTS

The frequency of the TT, TG, and GG of MDM2-SNP309 genotypes in the patients was obtained as 23%, 52%, and 25%, and they were equal to 22%, 40%, and 38% in the control group, respectively. Also, considering the MDM2-del1518 polymorphism, the frequencies of ins/ins, ins/del, and del/del genotypes were equal to 52%, 41%, and 7% in the breast cancer group and they were equal to 62, 30, and 8% in the control group, respectively. Analysis of the results indicated that the GG genotype plays a protective role for the breast cancer in the recessive model (GG vs TT + TG) of SNP309 (χ2  = 3.916, P = .048, and OR = 0.54).

CONCLUSION

Our findings revealed that the GG genotype of MDM2-SNP309 can play a protective role in the breast cancer disease. Also, our systematic review indicated that the SNP309, SNP285, and del1518 of MDM2 gene in different populations mostly did not have a significant association with the risk of breast cancer.

Exploring Dysregulated Signaling Pathways in Cancer

Cancer cell biology takes advantage of identifying diverse cellular signaling pathways that are disrupted in cancer. Signaling pathways are an important means of communication from the exterior of cell to intracellular mediators, as well as intracellular interactions that govern diverse cellular processes. Oncogenic mutations or abnormal expression of signaling components disrupt the regulatory networks that govern cell function, thus enabling tumor cells to undergo dysregulated mitogenesis, to resist apoptosis, and to promote invasion to neighboring tissues. Unraveling of dysregulated signaling pathways may advance the understanding of tumor pathophysiology and lead to the improvement of targeted tumor therapy. In this review article, different signaling pathways and how their dysregulation contributes to the development of tumors have been discussed.

The Roles of Cullin-2 E3 Ubiquitin Ligase Complex in Cancer

Posttranslational protein modifications play an important role in regulating protein stability and cellular function. There are at least eight Cullin family members. Among them, Cullin-2 forms a functional E3 ligase complex with elongin B, elongin C, RING-box protein 1 (RBX1, also called ROC1), as well as the substrate recognition subunit (SRS) to promote the substrate ubiquitination and degradation. In this book chapter, we will review Cullin-2 E3 ligase complexes that include various SRS proteins, including von Hippel Lindau (pVHL), leucine-rich repeat protein-1 (LRR-1), preferentially expressed antigen of melanoma (PRAME), sex-determining protein FEM-1 and early embryogenesis protein ZYG-11. We will focus on the VHL signaling pathway in clear cell renal cell carcinoma (ccRCC), which may reveal various therapeutic avenues in treating this lethal cancer.

The role of MDM2 amplification and overexpression in therapeutic resistance of malignant tumors

The MDM2 protein encoded by the mouse double minute 2 (MDM2) gene is the primary negative regulatory factor of the p53 protein. MDM2 can ligate the p53 protein via its E3 ubiquitin ligase, and the ubiquitinated p53 can be transferred to the cytoplasm and degraded by proteasomes. Therefore, MDM2 can maintain the stability of p53 signaling pathway. MDM2 amplification has been detected in many human malignancies, including lung cancer, colon cancer and other malignancies. MDM2 overexpression is associated with chemotherapeutic resistance in human malignancies. The mechanisms of chemotherapeutic resistance by MDM2 overexpression mainly include the p53–MDM2 loop-dependent and p53–MDM2 loop-independent pathways. But the role of MDM2 overexpression in tyrosine kinase inhibitors resistance remains to be further study. This paper reviews the possible mechanisms of therapeutic resistance of malignancies induced by MDM2 amplification and overexpression, including chemotherapy, radiotherapy, targeted agents and hyperprogressive disease of immunotherapy. Besides, MDM2-targeted therapy may be a potential new strategy for treating advanced malignancies.

Differential responses of epithelial cells from urinary and biliary tract to eggs of Schistosoma haematobium and S. mansoni

Chronic urogenital schistosomiasis can lead to squamous cell carcinoma of the bladder. The International Agency for Research on Cancer classifies the infection with S. haematobium as a group 1 carcinogen, a definitive cause of cancer. By contrast, hepatointestinal schistosomiasis due to the chronic infection with S. mansoni or S. japonicum associated with liver periportal fibrosis, does not apparently lead to malignancy. The effects of culturing human epithelial cells, HCV29, established from normal urothelium, and H69, established from cholangiocytes, in the presence of S. haematobium or S. mansoni eggs were investigated. Cell growth of cells co-cultured with schistosome eggs was monitored in real time, and gene expression analysis of oncogenesis, epithelial to mesenchymal transition and apoptosis pathways was undertaken. Schistosome eggs promoted proliferation of the urothelial cells but inhibited growth of cholangiocytes. In addition, the tumor suppressor P53 pathway was significantly downregulated when exposed to schistosome eggs, and downregulation of estrogen receptor was predicted in urothelial cells exposed only to S. haematobium eggs. Overall, cell proliferative responses were influenced by both the tissue origin of the epithelial cells and the schistosome species.

The past, present and future of potential small-molecule drugs targeting p53-MDM2/MDMX for cancer therapy

The p53 gene, a well-known tumor suppressor gene, plays a crucial role in cell cycle regulation, DNA repair, cell differentiation, and apoptosis. MDM2 exerts p53-dependent activity mainly by binding to p53 protein to form MDM2-p53 negative feedback loop. In addition, MDM2 is involved in a number of pathways that regulate cell proliferation and apoptosis, playing a p53-independent role. The p53 binding domain of MDMX bind to p53 transcriptional activation domain, inhibiting the transcriptional activity of p53 on its downstream genes, but does not mediate the degradation of p53. The anti-tumor effect is exerted by inhibiting the interaction between the MDM2/MDMX protein and the p53 protein by a small-molecule or by restoring the activity of the p53 protein. This review describes in the structural features, biological functions and mechanisms of p53-MDM2/MDMX, and summarizes small-molecule targeting p53-MDM2/MDMX.

Writing Histone Monoubiquitination in Human Malignancy-The Role of RING Finger E3 Ubiquitin Ligases

There is growing evidence highlighting the importance of monoubiquitination as part of the histone code. Monoubiquitination, the covalent attachment of a single ubiquitin molecule at specific lysines of histone tails, has been associated with transcriptional elongation and the DNA damage response. Sites function as scaffolds or docking platforms for proteins involved in transcription or DNA repair; however, not all sites are equal, with some sites resulting in actively transcribed chromatin and others associated with gene silencing. All events are written by E3 ubiquitin ligases, predominantly of the RING (really interesting new gene) finger type. One of the most well-studied events is monoubiquitination of histone H2B at lysine 120 (H2Bub1), written predominantly by the RING finger complex RNF20-RNF40 and generally associated with active transcription. Monoubiquitination of histone H2A at lysine 119 (H2AK119ub1) is also well-studied, its E3 ubiquitin ligase constituting part of the Polycomb Repressor Complex 1 (PRC1), RING1B-BMI1, associated with transcriptional silencing. Both modifications are activated as part of the DNA damage response. Histone monoubiquitination is a key epigenomic event shaping the chromatin landscape of malignancy and influencing how cells respond to DNA damage. This review discusses a number of these sites and the E3 RING finger ubiquitin ligases that write them.

The Study of MDM2 rs937283 Variant and Cancer Susceptibility in a Central Chinese Population

The rs937283 variant, locating in murine double minute 2 promoter region, has been previously reported to potentially alter the promoter activity and to influence cancer susceptibility. In this study, we investigated the association of murine double minute 2 rs937283 variant and cancer susceptibility in a central Chinese population, followed by a meta-analysis. A total of 1058 healthy controls, 480 patients with breast cancer, 384 patients with cervical cancer, 480 patients with liver cancer, 426 patients with colon cancer, and 361 patients with rectal cancer were recruited in this case–control study. The murine double minute 2 rs937283 was genotyped by polymerase chain reaction restriction fragment length polymorphism and confirmed by sequencing. Our case–control analysis revealed that rs937283 was associated with the susceptibility to breast and liver cancer, but not cervical, colon, or rectal cancer. Specifically, the G allele of rs937283 conferred a significantly increased risk of breast and liver cancer. Moreover, results of meta-analysis demonstrated that rs937283 was significantly associated with cancer susceptibility, and this significant association remained in Asian (Chinese) population, but not in Caucasian population. Collectively, the murine double minute 2 rs937283 variant may serve as a potential biomarker for cancer predisposition in Chinese population.