The Role of MDM2 Amplification and Overexpression in Tumorigenesis

The ribosomal protein L22 binds the MDM4 pre-mRNA and promotes exon skipping to activate p53 upon nucleolar stress

The tumor suppressor p53 and its antagonists MDM2 and MDM4 integrate stress signaling. For instance, dysbalanced assembly of ribosomes in nucleoli induces p53. Here, we show that the ribosomal protein L22 (RPL22; eL22), under conditions of ribosomal and nucleolar stress, promotes the skipping of MDM4 exon 6. Upon L22 depletion, more full-length MDM4 is maintained, leading to diminished p53 activity and enhanced cellular proliferation. L22 binds to specific RNA elements within intron 6 of MDM4 that correspond to a stem-loop consensus, leading to exon 6 skipping. Targeted deletion of these intronic elements largely abolishes L22-mediated exon skipping and re-enables cell proliferation, despite nucleolar stress. L22 also governs alternative splicing of the L22L1 (RPL22L1) and UBAP2L mRNAs. Thus, L22 serves as a signaling intermediate that integrates different layers of gene expression. Defects in ribosome synthesis lead to specific alternative splicing, ultimately triggering p53-mediated transcription and arresting cell proliferation.

A first-in-human phase I study of a novel MDM2/p53 inhibitor alrizomadlin in advanced solid tumors

BACKGROUND

The mouse double minute 2 homolog (MDM2) oncogene exerts oncogenic activities in many cancers and represents a potential therapeutic target. This trial evaluated the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of alrizomadlin (APG-115), a novel MDM2/p53 inhibitor, in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients with histologically confirmed advanced solid tumors who had progressed to standard treatment or lacked effective therapies were recruited. Alrizomadlin was administered once daily every other day for 21 days of a 28-day cycle until disease progression or intolerable toxicity.

RESULTS

A total of 21 patients were enrolled and treated with alrizomadlin; 57.1% were male and the median age was 47 (25-60) years. The maximum tolerated dose of alrizomadlin was 150 mg and the recommended phase II dose was 100 mg. One patient in the 200-mg cohort experienced dose-limiting toxicity of thrombocytopenia and febrile neutropenia. The most common grade 3/4 treatment-related adverse events were thrombocytopenia (33.3%), lymphocytopenia (33.3%), neutropenia (23.8%), and anemia (23.8%). Alrizomadlin demonstrated approximately linear pharmacokinetics (dose range 100-200 mg) and was associated with increased plasma macrophage inhibitory cytokine-1, indicative of p53 pathway activation. Of the 20 assessable patients, 2 [10%, 95% confidence interval (CI) 1.2% to 31.7%] patients achieved partial response and 10 (50%, 95% CI 27.2% to 72.8%) showed stable disease. The median progression-free survival was 6.1 (95% CI 1.7-10.4) months, which was significantly longer in patients with wild-type versus mutant TP53 (7.9 versus 2.2 months, respectively; P < 0.001). Among patients with MDM2 amplification and wild-type TP53, the overall response rate was 25% (2/8) and the disease control rate was 100% (8/8).

CONCLUSIONS

Alrizomadlin had an acceptable safety profile and demonstrated promising antitumor activity in MDM2-amplified and TP53 wild-type tumors. This study supports further exploration of alrizomadlin with recommended doses of 100 mg q.o.d. in 21 days on and 7 days off regimen.

HER4 Affects Sensitivity to Tamoxifen and Abemaciclib in Luminal Breast Cancer Cells and Restricts Tumor Growth in MCF-7-Based Humanized Tumor Mice

The impact of the HER4 receptor on the growth and treatment of estrogen receptor-positive breast cancer is widely uncertain. Using CRISPR/Cas9 technology, we generated stable HER4 knockout variants derived from the HER4-positive MCF-7, T-47D, and ZR-75-1 breast cancer cell lines. We investigated tumor cell proliferation as well as the cellular and molecular mechanisms of tamoxifen, abemaciclib, AMG232, and NRG1 treatments as a function of HER4 in vitro. HER4 differentially affects the cellular response to tamoxifen and abemaciclib treatment. Most conspicuous is the increased sensitivity of MCF-7 in vitro upon HER4 knockout and the inhibition of cell proliferation by NRG1. Additionally, we assessed tumor growth and immunological effects as responses to tamoxifen and abemaciclib therapy in humanized tumor mice (HTM) based on MCF-7 HER4-wildtype and the corresponding HER4-knockout cells. Without any treatment, the enhanced MCF-7 tumor growth in HTM upon HER4 knockout suggests a tumor-suppressive effect of HER4 under preclinical but human-like conditions. This phenomenon is associated with an increased HER2 expression in MCF-7 in vivo. Independent of HER4, abemaciclib and tamoxifen treatment considerably inhibited tumor growth in these mice. However, abemaciclib-treated hormone receptor-positive breast cancer patients with tumor-associated mdm2 gene copy gains or pronounced HER4 expression showed a reduced event-free survival. Evidently, the presence of HER4 affects the efficacy of tamoxifen and abemaciclib treatment in different estrogen receptor-positive breast cancer cells, even to different extents, and is associated with unfavorable outcomes in abemaciclib-treated patients.

The role of proteasomes in tumorigenesis

Protein homeostasis is the basis of normal life activities, and the proteasome family plays an extremely important function in this process. The proteasome 20S is a concentric circle structure with two α rings and two β rings overlapped. The proteasome 20S can perform both ATP-dependent and non-ATP-dependent ubiquitination proteasome degradation by binding to various subunits (such as 19S, 11S, and 200 PA), which is performed by its active subunit β1, β2, and β5. The proteasome can degrade misfolded, excess proteins to maintain homeostasis. At the same time, it can be utilized by tumors to degrade over-proliferate and unwanted proteins to support their growth. Proteasomes can affect the development of tumors from several aspects including tumor signaling pathways such as NF-κB and p53, cell cycle, immune regulation, and drug resistance. Proteasome-encoding genes have been found to be overexpressed in a variety of tumors, providing a potential novel target for cancer therapy. In addition, proteasome inhibitors such as bortezomib, carfilzomib, and ixazomib have been put into clinical application as the first-line treatment of multiple myeloma. More and more studies have shown that it also has different therapeutic effects in other tumors such as hepatocellular carcinoma, non-small cell lung cancer, glioblastoma, and neuroblastoma. However, proteasome inhibitors are not much effective due to their tolerance and singleness in other tumors. Therefore, further studies on their mechanisms of action and drug interactions are needed to investigate their therapeutic potential.

Personalized Medicine in Pancreatic Cancer: The Promise of Biomarkers and Molecular Targeting with Dr. Michael J. Pishvaian

Pancreatic cancer, with its alarming rising incidence, is predicted to become the second deadliest type of solid tumor by 2040, highlighting the urgent need for improved diagnostic and treatment strategies. Despite medical advancements, the five-year survival rate for pancreatic cancer remains about 14%, dropping further when metastasized. This review explores the promise of biomarkers for early detection, personalized treatment, and disease monitoring. Molecular classification of pancreatic cancer into subtypes based on genetic mutations, gene expression, and protein markers guides treatment decisions, potentially improving outcomes. A plethora of clinical trials investigating different strategies are currently ongoing. Targeted therapies, among which those against CLAUDIN 18.2 and inhibitors of Claudin 18.1, have shown promise. Next-generation sequencing (NGS) has emerged as a powerful tool for the comprehensive genomic analysis of pancreatic tumors, revealing unique genetic alterations that drive cancer progression. This allows oncologists to tailor therapies to target specific molecular abnormalities. However, challenges remain, including limited awareness and uptake of biomarker-guided therapies. Continued research into the molecular mechanisms of pancreatic cancer is essential for developing more effective treatments and improving patient survival rates.

Follicular Dendritic Cell Sarcoma of the Parotid Gland: A Case Report and Review of Literature

Follicular dendritic cell sarcoma of the parotid gland is an extremely rare tumor, with only six cases reported in the literature. A 51-year-old female had a 3.0 cm tumor resected from the right parotid gland. The tumor exhibited solid sheets, whorls, fascicular pattern, and syncytium appearance with an indistinct cell border. The lymphocytic infiltrate was sprinkled throughout the neoplasm, with focal prominent perivascular cuffing. Immunohistochemically, it was positive for follicular dendritic cell markers CD21, CD23, and CD35. We aim to enhance the understanding of this neoplasm and alert pathologists to this rare entity in this region to avoid misdiagnosis.

Large atypical lipomatous tumour of the neck with mediastinal extension managed by transcervical excision

Tumours of adipose tissue origin are relatively rare in the head and neck. Here, we report a case of an unfamiliar lipomatous lesion that involved the neck and mediastinum. A nil-comorbid man in his 40s presented with a slowly progressive anterior neck swelling of 3 years, which was diagnosed as lipoma by histopathological sampling. Computed tomography demonstrated the lesion to be involving parapharyngeal and retropharyngeal spaces with mediastinal extension. The lesion was removed by the transcervical approach. The final histology of the excised specimen, with immunohistochemistry for mouse double minute 2 (MDM2) and p16, suggested an atypical lipomatous tumour (ALT). This report accentuates the occurrence of this rare neoplasm in the neck, which often mimics lipoma clinically. Although radiology can demonstrate suggestive features, histology with MDM2 and/or p16 positivity can confirm the diagnosis of ALT as against the lipoma. A successful transcervical excision, despite the deeper extension of the lesion between the critical structures of the neck and mediastinum, demonstrates the non-infiltrating nature of the tumour.

HER3 (ERBB3) amplification in liposarcoma - a putative new therapeutic target?

BACKGROUND

Liposarcomas are among the most common mesenchymal malignancies. However, the therapeutic options are still very limited and so far, targeted therapies had not yet been established. Immunotherapy, which has been a breakthrough in other oncological entities, seems to have no efficacy in liposarcoma. Complicating matters further, classification remains difficult due to the diversity of morphologies and nonspecific or absent markers in immunohistochemistry, leaving molecular pathology using FISH or sequencing as best options. Many liposarcomas harbor MDM2 gene amplifications. In close relation to the gene locus of MDM2, HER3 (ERBB3) gene is present and co-amplification could occur. Since the group of HER/EGFR receptor tyrosine kinases and its inhibitors/antibodies play a role in a broad spectrum of oncological diseases and treatments, and some HER3 inhibitors/antibodies are already under clinical investigation, we hypothesized that in case of HER3 co-amplifications a tumor might bear a further potential therapeutic target.

METHODS

We performed FISH analysis (MDM2, DDIT3, HER3) in 56 archived cases and subsequently performed reclassification to confirm the diagnosis of liposarcoma.

RESULTS

Next to 16 out of 56 cases needed to be re-classified, in 20 out of 54 cases, a cluster-amplification of HER3 could be detected, significantly correlating with MDM2 amplification. Our study shows that the entity of liposarcomas show specific molecular characteristics leading to reclassify archived cases by modern, established methodologies. Additionally, in 57.1% of these cases, HER3 was cluster-amplified profusely, presenting a putative therapeutic target for targeted therapy.

CONCLUSION

Our study serves as the initial basis for further investigation of the HER3 gene as a putative therapeutic target in liposarcoma.

MDM2 Inhibitors for Cancer Therapy: The Past, Present, and Future

Since its discovery over 35 years ago, MDM2 has emerged as an attractive target for the development of cancer therapy. MDM2's activities extend from carcinogenesis to immunity to the response to various cancer therapies. Since the report of the first MDM2 inhibitor more than 30 years ago, various approaches to inhibit MDM2 have been attempted, with hundreds of small-molecule inhibitors evaluated in preclinical studies and numerous molecules tested in clinical trials. Although many MDM2 inhibitors and degraders have been evaluated in clinical trials, there is currently no Food and Drug Administration (FDA)-approved MDM2 inhibitor on the market. Nevertheless, there are several current clinical trials of promising agents that may overcome the past failures, including agents granted FDA orphan drug or fast-track status. We herein summarize the research efforts to discover and develop MDM2 inhibitors, focusing on those that induce MDM2 degradation and exert anticancer activity, regardless of the p53 status of the cancer. We also describe how preclinical and clinical investigations have moved toward combining MDM2 inhibitors with other agents, including immune checkpoint inhibitors. Finally, we discuss the current challenges and future directions to accelerate the clinical application of MDM2 inhibitors. In conclusion, targeting MDM2 remains a promising treatment approach, and targeting MDM2 for protein degradation represents a novel strategy to downregulate MDM2 without the side effects of the existing agents blocking p53-MDM2 binding. Additional preclinical and clinical investigations are needed to finally realize the full potential of MDM2 inhibition in treating cancer and other chronic diseases where MDM2 has been implicated. SIGNIFICANCE STATEMENT: Overexpression/amplification of the MDM2 oncogene has been detected in various human cancers and is associated with disease progression, treatment resistance, and poor patient outcomes. This article reviews the previous, current, and emerging MDM2-targeted therapies and summarizes the preclinical and clinical studies combining MDM2 inhibitors with chemotherapy and immunotherapy regimens. The findings of these contemporary studies may lead to safer and more effective treatments for patients with cancers overexpressing MDM2.

TRAIL-induced apoptosis and proteasomal activity - Mechanisms, signalling and interplay

Programmed cell death, in particular apoptosis, is essential during development and tissue homeostasis, and also is the primary strategy to induce cancer cell death by cytotoxic therapies. Precision therapeutics targeting TRAIL death receptors are being evaluated as novel anti-cancer agents, while in parallel highly specific proteasome inhibitors have gained approval as drugs. TRAIL-dependent signalling and proteasomal control of cellular proteostasis are intricate processes, and their interplay can be exploited to enhance therapeutic killing of cancer cells in combination therapies. This review provides detailed insights into the complex signalling of TRAIL-induced pathways and the activities of the proteasome. It explores their core mechanisms of action, pharmaceutical druggability, and describes how their interplay can be strategically leveraged to enhance cell death responses in cancer cells. Offering this comprehensive and timely overview will allow to navigate the complexity of the processes governing cell death mechanisms in TRAIL- and proteasome inhibitor-based treatment conditions.

Intraosseous myolipoma of the calcaneus

A man in his 40s presented with an incidental finding of an osteolytic bone lesion. He sustained an ankle injury while inline skating, fracturing his lateral malleolus. Besides the fracture, radiographic imaging on the day of the injury incidentally revealed a well-defined solitary osteolytic lesion with a sclerotic rim within the right calcaneus. MRI showed an intraosseous, fat-containing lesion with focal contrast enhancement, assessed as an intraosseous lipoma with central necrosis. In the pathological analysis of a sample of the lesion an intraosseous myolipoma of the calcaneus was found-an unexpected and extraordinary finding. To prevent pathological fracturing, curettage and bone grafting were performed using autologous iliac crest bone in combination with allogenous bone chips.

Discovery of Novel Antitumor Small-Molecule Agent with Dual Action of CDK2/p-RB and MDM2/p53

Cell cycle-dependent kinase 2 (CDK2) is located downstream of CDK4/6 in the cell cycle and regulates cell entry into S-phase by binding to Cyclin E and hyper-phosphorylating Rb. Proto-oncogene murine double minute 2 (MDM2) is a key negative regulator of p53, which is highly expressed in tumors and plays an important role in tumorigenesis and progression. In this study, we identified a dual inhibitor of CDK2 and MDM2, III-13, which had good selectivity for inhibiting CDK2 activity and significantly reduced MDM2 expression. In vitro results showed that III-13 inhibited proliferation of a wide range of tumor cells, regardless of whether Cyclin E1 (CCNE1) was overexpressed or not. The results of in vivo experiments showed that III-13 significantly inhibited proliferation of tumor cells and did not affect body weight of mice. The results of the druggability evaluation showed that III-13 was characterized by low bioavailability and poor membrane permeability when orally administered, suggesting the necessity of further structural modifications. Therefore, this study provided a lead compound for antitumor drugs, especially those against CCNE1-amplified tumor proliferation.

Pharmacological reactivation of p53 in the era of precision anticancer medicine

p53, which is encoded by the most frequently mutated gene in cancer, TP53, is an attractive target for novel cancer therapies. Despite major challenges associated with this approach, several compounds that either augment the activity of wild-type p53 or restore all, or some, of the wild-type functions to p53 mutants are currently being explored. In wild-type TP53 cancer cells, p53 function is often abrogated by overexpression of the negative regulator MDM2, and agents that disrupt p53-MDM2 binding can trigger a robust p53 response, albeit potentially with induction of p53 activity in non-malignant cells. In TP53-mutant cancer cells, compounds that promote the refolding of missense mutant p53 or the translational readthrough of nonsense mutant TP53 might elicit potent cell death. Some of these compounds have been, or are being, tested in clinical trials involving patients with various types of cancer. Nonetheless, no p53-targeting drug has so far been approved for clinical use. Advances in our understanding of p53 biology provide some clues as to the underlying reasons for the variable clinical activity of p53-restoring therapies seen thus far. In this Review, we discuss the intricate interactions between p53 and its cellular and microenvironmental contexts and factors that can influence p53's activity. We also propose several strategies for improving the clinical efficacy of these agents through the complex perspective of p53 functionality.

Bioinformatics analysis proposes a possible role for long noncoding RNA MIR17HG in retinoblastoma

BACKGROUND

Retinoblastoma (RB) is the most common prevalent intraocular malignancy among infants and children, particularly in underdeveloped countries. With advancements in genomics and transcriptomics, noncoding RNAs have been increasingly utilized to investigate the molecular pathology of diverse diseases.

AIMS

This study aims to establish the competing endogenous RNAs network associated with RB, analyse the function of mRNAs and lncRNAs, and finds the relevant regulatory network.

METHODS AND RESULTS

This study establishes a network of competing endogenous RNAs by Spearman correlation analysis and prediction based on RB patients and healthy children. Enrichment analyzes based on Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes are conducted to analyze the potential biological functions of lncRNA and mRNA networks. Weighted gene co-expression network analysis (WGCNA) is employed to identify gene cluster modules exhibiting the strongest correlation with RB. The results indicate a significant correlation between the lncRNA MIR17HG (R = .73, p = .02) and the RB phenotype. ceRNA networks reveal downstream miRNAs (hsa-mir-425-5p and hsa-mir455-5p) and mRNAs (MDM2, IPO11, and ITGA1) associated with MIR17Hg. As an inhibitor of the p53 signaling pathway, MDM2 can suppress the development of RB.

CONCLUSION

In conclusion, lncRNAs play a role in RB, and the MIR17HG/hsa-mir-425-5p/MDM2 pathway may contribute to RB development by inhibiting the p53 signaling pathway.

MDMX in Cancer: A Partner of p53 and a p53-Independent Effector

The p53 tumor suppressor protein plays an important role in physiological and pathological processes. MDM2 and its homolog MDMX are the most important negative regulators of p53. Many studies have shown that MDMX promotes the growth of cancer cells by influencing the regulation of the downstream target gene of tumor suppressor p53. Studies have found that inhibiting the MDMX-p53 interaction can effectively restore the tumor suppressor activity of p53. MDMX has growth-promoting activities without p53 or in the presence of mutant p53. Therefore, it is extremely important to study the function of MDMX in tumorigenesis, progression and prognosis. This article mainly reviews the current research progress and mechanism on MDMX function, summarizes known MDMX inhibitors and provides new ideas for the development of more specific and effective MDMX inhibitors for cancer treatment.

MDM2-p53 mediate a miR-181c-3p/LIF axis to regulate low dose-rate radiation-induced DNA damage in human B lymphocytes

PURPOSE

Prolonged exposure to low dose-rate radiation (LDRR) is of growing concern to public health. Recent evidences indicates that LDRR causes deleterious health effects and is closely related to miRNAs. The aim of our study is to investigate the relationship between miRNAs and DNA damage caused by LDRR.

MATERIALS AND METHODS

In this study, we irradiated C57BL/6J mice with 12.5μGy/h dose of γ ray emitted from uranium ore for 8 h a day for 120 days at a total dose of 12 mGy, and identified differentially expressed miRNAs from the mice long-term exposed to LDRR through isolating serum RNAs, constructing small RNA library, Illumina sequencing. To further investigate the role of differential miRNA under LDRR，we first built DNA damage model in Immortal B cells irradiated with 12.5μGy/h dose of γ ray for 28 days at a total dose of 9.4 mGy. Then, we chose the highly conserved miR-181c-3p among 12 miRNA and its mechanism in alleviating DNA damage induced by LDRR was studied by transfection, quantitative PCR, luciferase assay, and Western blot.

RESULTS AND CONCLUSIONS

We have found that 12 differentially expressed miRNAs including miR-181c-3p in serum isolated from irradiated mice. Analysis of GO and KEGG indicated that target genes of theses 12 miRNA enriched in pathways related to membrane, protein binding and cancer. Long-term exposure to LDRR induced upregulation of gamma-H2A histone family member X (γ-H2AX) expression, a classical biomarker for DNA damage in B cells. miR-181c-3p inhibited Leukemia inhibitory factor (LIF) expression via combining its 3'UTR. LIF, MDM2, p53, and p-p53-s6 were upregulated after exposure to LDRR. In irradiated B cells, Transfection of miR-181c-3p reduced γ-H2AX expression and suppressed LIF and MDM2 protein levels, whereas p-p53-s6 expression was increased. As expected, the effect of LIF inhibition on irradiated B cells was similar to miR-181c-3p overexpression. Our results suggest that LDRR alters miRNA expression and induces DNA damage. Furthermore, miR-181c-3p can alleviate LDRR-induced DNA damage via the LIF/MDM2/p-p53-s6 pathway in human B lymphocytes. This could provide the basis for prevention and treatment of LDRR injury.

E3 ubiquitin ligases in lung cancer: Emerging insights and therapeutic opportunities

Aim In this review, we have attempted to provide the readers with an updated account of the role of a family of proteins known as E3 ligases in different aspects of lung cancer progression, along with insights into the deregulation of expression of these proteins during lung cancer. A detailed account of the therapeutic strategies involving E3 ligases that have been developed or currently under development has also been provided in this review. MATERIALS AND METHODS: The review article employs extensive literature search, along with differential gene expression analysis of lung cancer associated E3 ligases using the DESeq2 package in R, and the Gene Expression Profiling Interactive Analysis (GEPIA) database (http://gepia.cancer-pku.cn/). Protein expression analysis of CPTAC lung cancer samples was carried out using the UALCAN webtool (https://ualcan.path.uab.edu/index.html). Assessment of patient overall survival (OS) in response to high and low expression of selected E3 ligases was performed using the online Kaplan-Meier plotter (https://kmplot.com/analysis/index.php?p=background). KEY FINDINGS: SIGNIFICANCE: The review provides an in-depth understanding of the role of E3 ligases in lung cancer progression and an up-to-date account of the different therapeutic strategies targeting oncogenic E3 ligases for improved lung cancer management.

USP7 reduces the level of nuclear DICER, impairing DNA damage response and promoting cancer progression

Endoribonuclease DICER is an RNase III enzyme that mainly processes microRNAs in the cytoplasm but also participates in nuclear functions such as chromatin remodelling, epigenetic modification and DNA damage repair. The expression of nuclear DICER is low in most human cancers, suggesting a tight regulation mechanism that is not well understood. Here, we found that ubiquitin carboxyl-terminal hydrolase 7 (USP7), a deubiquitinase, bounded to DICER and reduced its nuclear protein level by promoting its ubiquitination and degradation through MDM2, a newly identified E3 ubiquitin-protein ligase for DICER. This USP7-MDM2-DICER axis impaired histone γ-H2AX signalling and the recruitment of DNA damage response (DDR) factors, possibly by influencing the processing of small DDR noncoding RNAs. We also showed that this negative regulation of DICER by USP7 via MDM2 was relevant to human tumours using cellular and clinical data. Our findings revealed a new way to understand the role of DICER in malignant tumour development and may offer new insights into the diagnosis, treatment and prognosis of cancers.

CLDN6 inhibits colorectal cancer proliferation dependent on restraining p53 ubiquitination via ZO-1/PTEN axis

Colorectal cancer (CRC) is one of the most common cancers in the world. Abnormal proliferation is a chief characteristic of cancer and is the initiation of CRC progression. As an important component of tight junctions, CLDN6 regulates the proliferation of multiple tumors. Our previous study showed that CLDN6 was low expressed in CRC, and CLDN6 overexpression inhibited CRC proliferation. However, the specific mechanism of how CLDN6 works remains unclear. This research aimed to reveal the relationship between CLDN6 and clinical features, as well as the molecular mechanism by which CLDN6 inhibited CRC proliferation. We found that low expression of CLDN6 was associated with pathological grade and prognosis of CRC patients, and confirmed that CLDN6 inhibited CRC proliferation dependent on p53. Mechanically, we elucidated that CLDN6 regulated ubiquitination to enhance p53 stability and nuclear import by PTEN/AKT/MDM2 pathway. Through the PDZ-binding motif (PBM), CLDN6 bound to ZO-1 to interact with PTEN, and regulate AKT/MDM2 pathway. Collectively, our data enriched the theoretical basis for CLDN6 as a potential biomarker for diagnosis, therapy and prognosis of CRC.

Sarcoma care in the era of precision medicine

Sarcoma subtype classification is currently mainly based upon histopathological morphology. Molecular analyses have emerged as an efficient addition to the diagnostic workup and sarcoma care. Knowledge about the sarcoma genome increases, and genetic events that can either support a histopathological diagnosis or suggest a differential diagnosis are identified, as well as novel therapeutic targets. In this review, we present diagnostic, therapeutic, and prognostic molecular markers that are, or might soon be, used clinically. For sarcoma diagnostics, there are specific fusions highly supportive or pathognomonic for a diagnostic entity-for instance, SYT::SSX in synovial sarcoma. Complex karyotypes also give diagnostic information-for example, supporting dedifferentiation rather than low-grade central osteosarcoma or well-differentiated liposarcoma when detected in combination with MDM2/CDK4 amplification. Molecular treatment predictive sarcoma markers are available for gastrointestinal stromal tumor (GIST) and locally aggressive benign mesenchymal tumors. The molecular prognostic markers for sarcomas in clinical practice are few. For solitary fibrous tumor, the type of NAB2::STAT6 fusion is associated with the outcome, and the KIT/PDGFRA pathogenic variant in GISTs can give prognostic information. With the exploding availability of sequencing technologies, it becomes increasingly important to understand the strengths and limitations of those methods and their context in sarcoma diagnostics. It is reasonable to believe that most sarcoma treatment centers will increase the use of massive-parallel sequencing soon. We conclude that the context in which the genetic findings are interpreted is of importance, and the interpretation of genomic findings requires considering tumor histomorphology.

MDM2 amplification is rare in gastric cancer

The MDM2 proto-oncogene (MDM2) is a primary negative regulator of p53. The latter is frequently mutated in gastric cancer (GC). In the present study, we aimed to validate gene amplification, protein expression, and the putative tumor biological function of MDM2 in a well-characterized Western GC cohort. MDM2 amplification and protein expression were studied in a cohort of 327 GCs by fluorescence in situ hybridization (FISH) and immunohistochemistry. Gene amplification and protein expression were correlated with diverse clinicopathological patient characteristics including patient outcome. Immunohistochemically, 97 GCs (29.7%) were categorized as MDM2 positive and 230 GCs (70.3%) as negative. An amplification of MDM2 was found in 11 (3.4%) cases without evidence of intratumoral heterogeneity. Nine of these eleven (81.8%) cases showed MDM2 protein expression. MDM2 amplification correlated significantly with MDM2 protein expression (p < 0.001). On a case-by-case analysis, MDM2-amplified cases showed varied histological phenotypes and were most commonly microsatellite stable; EBV, HER2, and MET negative; and FGFR2 positive. A single case harbored both, MDM2 amplification and TP53 mutation. MDM2 amplification and MDM2 expression, respectively, did not correlate with overall or tumor-specific survival. Our targeted analysis of MDM2 in a well-characterized cohort of GC patients showed that MDM2 amplification is rare, of no specific histological phenotype, and may not be always mutually exclusive with TP53 mutations. Given the low number of cases, currently, no diagnostic or therapeutic recommendation related to MDM2 amplification can be given for GC of Western origin.

MDM2-Targeting Reassembly Peptide (TRAP) Nanoparticles for p53-Based Cancer Therapy

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.

Targeting apoptosis dysregulation in myeloid malignancies - The promise of a therapeutic revolution

In recent years, the therapeutic landscape of myeloid malignancies has been completely revolutionized by the introduction of several new drugs, targeting molecular alterations or pathways crucial for leukemia cells survival. Particularly, many agents targeting apoptosis have been investigated in both pre-clinical and clinical studies. For instance, venetoclax, a pro-apoptotic agent active on BCL-2 signaling, has been successfully used in the treatment of acute myeloid leukemia (AML). The impressive results achieved in this context have made the apoptotic pathway an attractive target also in other myeloid neoplasms, translating the experience of AML. Therefore, several drugs are now under investigation either as single or in combination strategies, due to their synergistic efficacy and capacity to overcome resistance. In this paper, we will review the mechanisms of apoptosis and the specific drugs currently used and under investigation for the treatment of myeloid neoplasia, identifying critical research necessities for the upcoming years.

A comprehensive review of Tripterygium wilfordii hook. f. in the treatment of rheumatic and autoimmune diseases: Bioactive compounds, mechanisms of action, and future directions

Rheumatic and autoimmune diseases are a group of immune system-related disorders wherein the immune system mistakenly attacks and damages the body's tissues and organs. This excessive immune response leads to inflammation, tissue damage, and functional impairment. Therapeutic approaches typically involve medications that regulate immune responses, reduce inflammation, alleviate symptoms, and target specific damaged organs. Tripterygium wilfordii Hook. f., a traditional Chinese medicinal plant, has been widely studied in recent years for its application in the treatment of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, and multiple sclerosis. Numerous studies have shown that preparations of Tripterygium wilfordii have anti-inflammatory, immunomodulatory, and immunosuppressive effects, which effectively improve the symptoms and quality of life of patients with autoimmune diseases, whereas the active metabolites of T. wilfordii have been demonstrated to inhibit immune cell activation, regulate the production of inflammatory factors, and modulate the immune system. However, although these effects contribute to reductions in inflammatory responses and the suppression of autoimmune reactions, as well as minimize tissue and organ damage, the underlying mechanisms of action require further investigation. Moreover, despite the efficacy of T. wilfordii in the treatment of autoimmune diseases, its toxicity and side effects, including its potential hepatotoxicity and nephrotoxicity, warrant a thorough assessment. Furthermore, to maximize the therapeutic benefits of this plant in the treatment of autoimmune diseases and enable more patients to utilize these benefits, efforts should be made to strengthen the regulation and standardized use of T. wilfordii.

Somatic evolution of marine transmissible leukemias in the common cockle, Cerastoderma edule

Transmissible cancers are malignant cell lineages that spread clonally between individuals. Several such cancers, termed bivalve transmissible neoplasia (BTN), induce leukemia-like disease in marine bivalves. This is the case of BTN lineages affecting the common cockle, Cerastoderma edule, which inhabits the Atlantic coasts of Europe and northwest Africa. To investigate the evolution of cockle BTN, we collected 6,854 cockles, diagnosed 390 BTN tumors, generated a reference genome and assessed genomic variation across 61 tumors. Our analyses confirmed the existence of two BTN lineages with hemocytic origins. Mitochondrial variation revealed mitochondrial capture and host co-infection events. Mutational analyses identified lineage-specific signatures, one of which likely reflects DNA alkylation. Cytogenetic and copy number analyses uncovered pervasive genomic instability, with whole-genome duplication, oncogene amplification and alkylation-repair suppression as likely drivers. Satellite DNA distributions suggested ancient clonal origins. Our study illuminates long-term cancer evolution under the sea and reveals tolerance of extreme instability in neoplastic genomes.

The ubiquitin E3 ligase MDM2 induces chemoresistance in colorectal cancer by degradation of ING3

Chemoresistance is an obstacle for colorectal cancer (CRC) treatment. This study investigates the role of the ubiquitin E3 ligase MDM2 in affecting cell growth and chemosensitivity in CRC cells by modifying the transcription factor inhibitor of growth protein 3 (ING3). The expression of MDM2 and ING3 in CRC tissues was predicted by bioinformatics analysis, followed by expression validation and their interaction in CRC HCT116 and LS180 cells. Ectopic overexpression or knockdown of MDM2/ING3 was performed to test their effect on proliferation and apotptosis as well as chemosensitivity of CRC cells. Finally, the effect of MDM2/ING3 expression on the in vivo tumorigenesis of CRC cells was examined through subcutaneous tumor xenograft experiment in nude mice. MDM2 promoted ubiquitin-proteasome pathway degradation of ING3 through ubiquitination and diminished its protein stability. Overexpression of MDM2 downregulated ING3 expression, which promoted CRC cell proliferation and inhibited the apoptosis. The enhancing role of MDM2 in tumorigenesis and resistance to chemotherapeutic drugs was also confirmed in vivo. Our findings highlight that MDM2 modifies the transcription factor ING3 by ubiquitination-proteasome pathway degradation, thus reducing ING3 protein stability, which finally promotes CRC cell growth and chemoresistance.

Cytoplasmic localization of Mdm2 in cells expressing mutated NPM is mediated by p53

Specific C-terminal nucleophosmin (NPM) mutations are related to the acute myeloid leukaemia and cause mistargeting of mutated NPM (NPMmut) to the cytoplasm. Consequently, multiple NPM-interacting partners, e.g., the tumour suppressor p53, become also mislocalized. We found that ubiquitin ligase Mdm2 mislocalizes to the cytoplasm in the presence of NPMmut as well. Since p53 interacts with Mdm2, we searched for the NPMmut-p53-Mdm2 complex and interactions of its constituents in live cells and cell lysates using fluorescently tagged proteins, fluorescence lifetime imaging and immunoprecipitation. We proved existence of the ternary complex, which likely adopts a chain-like configuration. Interaction between Mdm2 and NPMmut was not detected, even under conditions of upregulated Mdm2 and p53 induced by Actinomycin D. We assume that p53 serves in the complex as a bridging link between Mdm2 and NPMmut. This conclusion was supported by disruption of the Mdm2-p53 interaction by Nutlin-3A, which resulted in relocalization of Mdm2 to the nucleus, while both NPMmut and p53 remained in the cytoplasm. Importantly, silencing of p53 also prevented mislocalization of Mdm2 in the presence of NPMmut.

LncRNA NRON promotes tumorigenesis by enhancing MDM2 activity toward tumor suppressor substrates

The E3 ligase MDM2 promotes tumor growth and progression by inducing ubiquitin-mediated degradation of P53 and other tumor-suppressing proteins. Here, we identified an MDM2-interacting lncRNA NRON, which promotes tumor formation by suppressing both P53-dependent and independent pathways. NRON binds to MDM2 and MDMX (MDM4) via two different stem-loops, respectively, and induces their heterogenous dimerization, thereby enhancing the E3 ligase activity of MDM2 toward its tumor-suppressing substrates, including P53, RB1, and NFAT1. NRON knockdown dramatically inhibits tumor cell growth in vitro and in vivo. More importantly, NRON overexpression promotes oncogenic transformation by inducing anchorage-independent growth in vitro and facilitating tumor formation in immunocompromised mice. Clinically, NRON expression is significantly associated with poor clinical outcome in breast cancer patients. Together, our data uncover a pivotal role of lncRNA that induces malignant transformation of epithelial cells by inhibiting multiple tumor suppressor proteins.

Molecular biology of microRNA-342 during tumor progression and invasion

Cancer is considered as one of the main causes of human deaths and health challenges in the world. Various factors are involved in the high death rate of cancer patients, including late diagnosis and drug resistance that result in treatment failure and tumor recurrence. Invasive diagnostic methods are one of the main reasons of late tumor detection in cancer patients. Therefore, it is necessary to investigate the molecular tumor biology to introduce efficient non-invasive markers. MicroRNAs (miRNAs) are involved in regulation of the cellular mechanisms such as cell proliferation, apoptosis, and migration. MiRNAs deregulations have been also frequently shown in different tumor types. Here, we discussed the molecular mechanisms of miR-342 during tumor growth. MiR-342 mainly functions as a tumor suppressor by the regulation of transcription factors and signaling pathways such as WNT, PI3K/AKT, NF-kB, and MAPK. Therefore, miR-342 mimics can be used as a reliable therapeutic strategy to inhibit the tumor cells growth. The present review can also pave the way to introduce the miR-342 as a non-invasive diagnostic/prognostic marker in cancer patients.

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.

Immortalization and transformation of primary cells mediated by engineered ecDNAs

Focal gene amplifications are among the most common cancer-associated mutations, but their evolution and contribution to tumorigenesis have proven challenging to recapitulate in primary cells and model organisms. Here we describe a general approach to engineer large (>1 Mbp) focal amplifications mediated by extrachromosomal circular DNAs (ecDNAs, also known as "double minutes") in a spatiotemporally controlled manner in cancer cell lines and in primary cells derived from genetically engineered mice. With this strategy, ecDNA formation can be coupled with expression of fluorescent reporters or other selectable markers to enable the identification and tracking of ecDNA-containing cells. We demonstrate the feasibility of this approach by engineering MDM2-containing ecDNAs in near-diploid human cells, showing that GFP expression can be used to track ecDNA dynamics under physiological conditions or in the presence of specific selective pressures. We also apply this approach to generate mice harboring inducible Myc - and Mdm2 -containing ecDNAs analogous to those spontaneously occurring in human cancers. We show that the engineered ecDNAs rapidly accumulate in primary cells derived from these animals, promoting proliferation, immortalization, and transformation.

Mechanistic insights into genomic structure and functions of a novel oncogene YEATS4

As a novel oncogene, the role of YEATS domain-containing protein 4 (YEATS4) in the occurrence, development, and treatment of tumors is now beginning to be appreciated. YEATS4 plays an important role in regulating DNA repair during replication. The upregulation of YEAST4 promotes DNA damage repair and prevents cell death, whereas its downregulation inhibits DNA replication and induces apoptosis. Additionally, accumulating evidence indicates that the aberrant activation of YEATS4 leads to changes in drug resistance, epithelial-mesenchymal transition and also in the migration and invasion capacity of tumor cells. Therefore, specific inhibition of the expression or activity of YEATS4 protein may be an effective strategy for inhibiting the proliferation, motility, differentiation, and/or survival of tumor cells. Taken together, YEATS4 has emerged as a potential target for multiple cancers and is an attractive protein for the development of small-molecule inhibitors. However, research on YEAST4 in tumor-related fields is limited and its biological functions, metabolism, and the regulatory mechanism of YEATS4 in numerous cancers remain undetermined. This review comprehensively and extensively summarizes the functions, structure and oncogenic roles of YEATS4 in cancer progression and aims to further contribute to the study of its underlying molecular mechanism and targeted drugs.

Small-molecule correctors and stabilizers to target p53

The tumor suppressor p53 is the most frequently mutated protein in human cancer and tops the list of high-value precision oncology targets. p53 prevents initiation and progression of cancer by inducing cell-cycle arrest and various forms of cell death. Tumors have thus evolved ways to inactivate p53, mainly by TP53 mutations or by hyperactive p53 degradation. This review focuses on two types of p53 targeting compounds, MDM2 antagonists and mutant p53 correctors. MDM2 inhibitors prevent p53 protein degradation, while correctors restore tumor suppressor activity of p53 mutants by enhancing thermodynamic stability. Herein we explore both novel and repurposed p53 targeting compounds, discuss their mode of action, and examine the challenges in advancing them to the clinic.

Tissue specificity and spatio-temporal dynamics of the p53 transcriptional program

Transcription factors regulate hundreds of genes and p53 is no exception. As a stress responsive protein, p53 transactivates an array of downstream targets which define its role in maintaining physiological functions of cells/tissues. Despite decades of studies, our understanding of the p53 in vivo transcriptional program is still incomplete. Here we discuss some of the physiological stressors that activate p53, the pathological and physiological implications of p53 activation and the molecular profiling of the p53 transcriptional program in maintaining tissue homeostasis. We argue that the p53 transcriptional program is spatiotemporally regulated in a tissue-specific manner and define a p53 target signature that faithfully depicts p53 activity. We further emphasize that additional in vivo studies are needed to refine the p53 transactivation profile to harness it for therapeutic purposes.

CopA3 peptide inhibits MDM2-p53 complex stability in colorectal cancers and activates p53 mediated cell death machinery

The diverse expression patterns of the tumor suppressor p53 in cancer cells reflect the regulatory efficiency of multiple cellular pathways. By contrast, many human tumors are reported to develop in the presence of wild-type p53. Recently, several oncogene inhibitors have been used clinically to suppress tumor development by functionally reactivating other oncoproteins. On the other hand, p53 reactivation therapies have not been well established, as few of the p53-MDM2 complex inhibitors such as Nutlin-3 induces mutation in p53 gene upon prolonged usage. Therefore, in this study CopA3, a 9-mer dimeric D-type peptide with anticancer activity against the human colorectal cancer cells, was used to explore the efficacy of p53 reactivation in-vitro and in-vivo. The anticancer activity of CopA3 was more selective towards the wild-type p53 expressing cells than the p53 deficient or mutant colorectal cancer cells. In response to this, this study investigated the signaling pathway in vitro and validated its anti-tumor activity in-vivo. The protein-peptide interaction and molecular docking efficiently provided insight into the specific binding affinity of CopA3 to the p53-binding pocket of the MDM2 protein, which efficiently blocked the p53 and MDM2 interaction. CopA3 plays a crucial role in the binding with MDM2 and enhanced the nuclear translocation of the p53 protein, which sequentially activated the downstream targets to trigger the autophagic mediated cell death machinery through the JNK/Beclin-1 mediated pathway. Collectively, CopA3 affected the MDM2-p53 interaction, which suppressed tumor development. This study may provide a novel inhibitor candidate for the MDM2-p53 complex, which could ultimately suppress the growth of colorectal cancer cells without being cytotoxic to the healthy neighboring cells present around the tumor microenvironment.

Deep thermal profiling for detection of functional proteoform groups

The complexity of the functional proteome extends considerably beyond the coding genome, resulting in millions of proteoforms. Investigation of proteoforms and their functional roles is important to understand cellular physiology and its deregulation in diseases but challenging to perform systematically. Here we applied thermal proteome profiling with deep peptide coverage to detect functional proteoform groups in acute lymphoblastic leukemia cell lines with different cytogenetic aberrations. We detected 15,846 proteoforms, capturing differently spliced, cleaved and post-translationally modified proteins expressed from 9,290 genes. We identified differential co-aggregation of proteoform pairs and established links to disease biology. Moreover, we systematically made use of measured biophysical proteoform states to find specific biomarkers of drug sensitivity. Our approach, thus, provides a powerful and unique tool for systematic detection and functional annotation of proteoform groups.

The roles of E3 ubiquitin ligases in cancer progression and targeted therapy

Ubiquitination is one of the most important post-translational modifications which plays a significant role in conserving the homeostasis of cellular proteins. In the ubiquitination process, ubiquitin is conjugated to target protein substrates for degradation, translocation or activation, dysregulation of which is linked to several diseases including various types of cancers. E3 ubiquitin ligases are regarded as the most influential ubiquitin enzyme owing to their ability to select, bind and recruit target substrates for ubiquitination. In particular, E3 ligases are pivotal in the cancer hallmarks pathways where they serve as tumour promoters or suppressors. The specificity of E3 ligases coupled with their implication in cancer hallmarks engendered the development of compounds that specifically target E3 ligases for cancer therapy. In this review, we highlight the role of E3 ligases in cancer hallmarks such as sustained proliferation via cell cycle progression, immune evasion and tumour promoting inflammation, and in the evasion of apoptosis. In addition, we summarise the application and the role of small compounds that target E3 ligases for cancer treatment along with the significance of targeting E3 ligases as potential cancer therapy.

UBE2J1 knockdown promotes cell apoptosis in endometrial cancer via regulating PI3K/AKT and MDM2/p53 signaling

Emerging evidence has demonstrated that ubiquitin conjugating enzyme E2 J1 (UBE2J1) exerts pivotal function in many cancers. UBE2J1 was reported to be dysregulated in endometrial cancer (EC). This study was designed to further investigate the regulatory character and mechanism of UBE2J1 in EC. Bioinformatic tools and databases were used to analyze gene expression pattern and gene expression correlation in EC tissues, and the prognosis of EC patients. Gene expression was evaluated by reverse-transcription quantitative polymerase chain reaction. Western blot was used for protein level detection. In vitro cell apoptosis was detected by flow cytometry analyses and TUNEL assays. In vivo cell apoptosis was evaluated by detecting Bax and Bcl-2 expression in tumor tissues via immunohistochemical and western blot analyses. In this study, UBE2J1 knockdown promoted cell apoptosis in EC cells and in mouse models of EC. PI3K and AKT expression is positively correlated with UBE2J1 level and is related to poor prognosis of EC patients. UBE2J1 knockdown repressed the PI3K/AKT pathway both in vitro and in vivo. UBE2J1 downregulation decreased MDM2 expression, but increased p53 expression. MDM2 overexpression reverses the promotion of UBE2J1 knockdown on cell apoptosis in EC. Overall, UBE2J1 knockdown induces cell apoptosis in EC by inactivating the PI3K/AKT signaling and suppressing the MDM2/p53 signaling.

Expression and Clinical Significance of MDM2 in Non-Functioning PitNETs

Background and Objective: Non-functioning pituitary neuroendocrine tumors (NF-PitNETs) represent a heterogeneous tumor type that lacks effective medical treatment. MDM2, the main negative regulator of p53, binds to and forms a stable complex with p53 to regulate its activity. In this study, we measured the expression levels and role of MDM2 in non-functioning PitNET patients' combined clinical features and investigated the effect of etoposide on the cell bioactivity of the GT1-1 cell line in vivo and in vitro. Methods: RT-PCR and immunochemistry measured the expression levels and role of MDM2 in 103 NF-PitNET patients' combined clinical features. Cell proliferation, migration, colony and apoptosis experiments measured the effect of etoposide on the GT1-1 cell line in vivo and in vitro. Results: There was more invasive behavior (p = 0.013) in patients with high MDM2, who were also younger (p = 0.007), were more frequently female (p = 0.049) and had larger tumor sizes (p = 0.018) compared with patients with low MDM2. Patients with high p53 were younger (p = 0.017) and had larger tumor sizes (p = 0.034) compared with patients with low p53. Univariate (p = 0.018) and multivariate (p = 0.023) Cox regression analysis showed that MDM2 was the independent factor for invasive behavior in NF-PitNET patients. Log-rank analysis showed that the average progression-free survival (PFS) time in the low MDM2 patients was longer than that in the high MDM2 patients (p = 0.044). Functional studies indicated that etoposide inhibited cell proliferation and cell migration and induced apoptosis in p53 independence in GT1-1 cells. Furthermore, etoposide significantly inhibited the growth of GT1-1-xenograft in BALB/c nude mice. The tumor growth inhibition rate of etoposide was 67.4 ± 4.6% after 14 d of treatment, which suggested the anti-tumor activity of etoposide. Conclusions: MDM2 played the role of tumorigenesis of NF-PitNET in a p53 independence manner, and an MDM2 inhibitor could be a potential choice for the treatment of NF-PitNET patients.

Drugging p53 in cancer: one protein, many targets

Mutations in the TP53 tumour suppressor gene are very frequent in cancer, and attempts to restore the functionality of p53 in tumours as a therapeutic strategy began decades ago. However, very few of these drug development programmes have reached late-stage clinical trials, and no p53-based therapeutics have been approved in the USA or Europe so far. This is probably because, as a nuclear transcription factor, p53 does not possess typical drug target features and has therefore long been considered undruggable. Nevertheless, several promising approaches towards p53-based therapy have emerged in recent years, including improved versions of earlier strategies and novel approaches to make undruggable targets druggable. Small molecules that can either protect p53 from its negative regulators or restore the functionality of mutant p53 proteins are gaining interest, and drugs tailored to specific types of p53 mutants are emerging. In parallel, there is renewed interest in gene therapy strategies and p53-based immunotherapy approaches. However, major concerns still remain to be addressed. This Review re-evaluates the efforts made towards targeting p53-dysfunctional cancers, and discusses the challenges encountered during clinical development.

Reduced murine double minute 2 and 4 protein, but not messenger RNA , expression is associated with more severe disease in myelodysplastic syndromes and acute myeloblastic leukaemia

The human homologues of murine double minute 2 (MDM2) and 4 (MDM4) negatively regulate p53 tumour suppressor activity and are reported to be frequently overexpressed in human malignancies, prompting clinical trials with drugs that prevent interactions between MDM2/MDM4 and p53. Bone marrow samples from 111 patients with acute myeloblastic leukaemia, myelodysplastic syndrome or chronic myelomonocytic leukaemia were examined for protein (fluorescence-activated cell sorting) and messenger RNA (mRNA) expression (quantitative polymerase chain reaction) of MDM2, MDM4 and tumour protein p53 (TP53). Low protein expression of MDM2 and MDM4 was observed in immature cells from patients with excess of marrow blasts (>5%) compared with CD34⁺ /CD45^low cells from healthy donors and patients without excess of marrow blasts (<5%). The mRNA levels were indistinguishable in all samples examined regardless of disease status or blast levels. Low MDM2 and MDM4 protein expression were correlated with poor survival. These data show a poor correlation between mRNA and protein expression levels, suggesting that quantitative flow cytometry analysis of protein expression levels should be used to predict and validate the efficacy of MDM2 and MDM4 inhibitors. These findings show that advanced disease is associated with reduced MDM2 and MDM4 protein expression and indicate that the utility of MDM2 and MDM4 inhibitors may have to be reconsidered in the treatment of advanced myeloid malignancies.

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.

Progress in Anticancer Drug Development Targeting Ubiquitination-Related Factors

Ubiquitination is extensively involved in critical signaling pathways through monitoring protein stability, subcellular localization, and activity. Dysregulation of this process results in severe diseases including malignant cancers. To develop drugs targeting ubiquitination-related factors is a hotspot in research to realize better therapy of human diseases. Ubiquitination comprises three successive reactions mediated by Ub-activating enzyme E1, Ub-conjugating enzyme E2, and Ub ligase E3. As expected, multiple ubiquitination enzymes have been highlighted as targets for anticancer drug development due to their dominant effect on tumorigenesis and cancer progression. In this review, we discuss recent progresses in anticancer drug development targeting enzymatic machinery components.

E3 ubiquitin ligases in the acute leukemic signaling pathways

Acute leukemia is a common hematologic tumor with highly genetic heterogeneity, and many factors are involved in the pathogenesis and drug-resistance mechanism. Emerging evidence proves that E3 ubiquitin ligases participate in the acute leukemic signaling pathways via regulating substrates. This review summarized the E3 ligases which can affect the leukemic signal. It is worth noting that the abnormal signal is often caused by a deficiency or a mutation of the E3 ligases. In view of this phenomenon, we envisioned perspectives associated with targeted agonists of E3 ligases and proteolysis-targeting chimera technology. Moreover, we emphasized the significance of research into the upstream factors regulating the expression of E3 ubiquitin ligases. It is expected that the understanding of the mechanism of leukemic signaling pathways with which that E3 ligases are involved will be beneficial to accelerating the process of therapeutic strategy improvement for acute leukemia.

Nonsense-mediated mRNA decay inhibition synergizes with MDM2 inhibition to suppress TP53 wild-type cancer cells in p53 isoform-dependent manner

The restoration of the normal function of the tumour suppressors, such as p53, is an important strategy in tumour therapeutics. Nonsense-mediated mRNA decay (NMD) inhibition by NMD inhibitor (NMDi) upregulates functional p53 isoforms, p53β and p53γ, and activates the p53 pathway. XR-2, a novel mouse double minute 2 homolog (MDM2) inhibitor, can disrupt the interaction between p53 and MDM2, thus decreasing the MDM2-mediated degradation of p53 and increasing the p53 protein levels. However, the combined effects of these two agents have not been thoroughly explored. This study combined XR-2 and NMDi in four TP53 wild-types and four TP53-mutated cancer cell lines. The combination of these two agents achieved significant synergistic effects on TP53 wild-type cancer cell lines by transactivating p53 target genes, inducing apoptosis, cell-cycle arrest and DNA damage repair. The p53β isoform induced by NMDi enhances the transactivation ability of p53α induced by XR-2, which partially explains the mechanism of the synergistic effects of XR-2 and NMDi. This study identified a combination treatment of NMDi and XR-2 which could serve as a novel cancer therapeutic approach for MDM2-overexpressed TP53 wild-type cancers and delineated a future therapy based on the further reactivation of p53.

Corosolic acid sensitizes ferroptosis by upregulating HERPUD1 in liver cancer cells

Primary liver cancer is the third leading cause of cancer death in the world, and the lack of effective treatments is the main reason for the high mortality. Corosolic acid (CA) has been proved to have antitumor activity. In this study, we found that CA can sensitize liver cancer cells to ferroptosis, which is a regulated form of cell death characterized by iron-dependent lipid peroxides reaching lethal levels. Here, we revealed that CA can inhibit glutathione (GSH) synthesis via HERPUD1, decreasing the cellular GSH level and causing liver cancer cells to become more sensitive to ferroptosis. Mechanistically, further studies found that HERPUD1 reduced the ubiquitination of the GSS-associated E3 ubiquitin ligase MDM2, which promoted ubiquitination of GSS, thereby inhibiting GSH synthesis to increase ferroptosis susceptibility. Importantly, a mouse xenograft model also demonstrated that CA inhibits tumor growth via HERPUD1. Collectively, our findings suggesting that CA is a candidate component for the development of treatments against liver cancer.

Identification of Key Genes and Pathways in Genotoxic Stress Induced Endothelial Dysfunction: Results of Whole Transcriptome Sequencing

Atherosclerosis is a leading cause of cardiovascular morbidity and mortality worldwide. Endothelial disfunction underlying the atherogenesis can be triggered by genotoxic stress in endothelial cells. In the presented research whole transcriptome sequencing (RNA-seq) of human coronary artery (HCAEC) and internal thoracic artery (HITAEC) endothelial cells in vitro exposed to 500 ng/mL mitomycin C (treatment group) or 0.9% NaCl (control group) was performed. Resulting to bioinformatic analysis, 56 upregulated differentially expressed genes (DEGs) and 6 downregulated DEGs with absolute fold change ≥ 2 and FDR p-value < 0.05 were selected in HCAEC exposed to mitomycin C compared to the control group; in HITAEC only one upregulated DEG was found. According to Gene Ontology enrichment analysis, DEGs in HCAEC were classified into 25 functional groups of biological processes, while in HITAEC we found no statistically significant (FDR p-value < 0.05) groups. The four largest groups containing more than 50% DEGs (“signal transduction”, “response to stimulus”, “biological regulation”, and “regulation of biological process”) were identified. Finally, candidate DEGs and pathways underlying the genotoxic stress induced endothelial disfunction have been discovered that could improve our understanding of fundamental basis of atherogenesis and help to justification of genotoxic stress as a novel risk factor for atherosclerosis.

Alpha Mangostin and Cisplatin as Modulators of Exosomal Interaction of Ovarian Cancer Cell with Fibroblasts

The diversity of exosomes and their role in the microenvironment make them an important point of interest in the development of cancer. In our study, we evaluated the effect of exosomes derived from ovarian cancer cells on gene expression in fibroblasts, including genes involved in metastasis. We also attempted to evaluate the indirect effect of cisplatin and/or α-mangostin on metastasis. In this aspect, we verified the changes induced by the drugs we tested on vesicular transfer associated with the release of exosomes by cells. We isolated exosomes from ovarian cancer cells treated and untreated with drugs, and then normal human fibroblasts were treated with the isolated exosomes. Changes in the expression of genes involved in the metastasis process were then examined. In our study, we observed altered expression of genes involved in various steps of the metastasis process (including genes related to cell adhesion, genes related to the interaction with the extracellular matrix, the cell cycle, cell growth and proliferation, and apoptosis). We have shown that α-mangostin and/or cisplatin, as chemotherapeutic agents, not only directly affect tumor cells but may also indirectly (via exosomes) contribute to delaying metastasis development.

Kaposi’s Sarcoma-Associated Herpesvirus ORF50 Protein Represses Cellular MDM2 Expression via Suppressing the Sp1- and p53-Mediated Transactivation

The Kaposi’s sarcoma-associated herpesvirus (KSHV)-encoded ORF50 protein is a potent transcriptional activator essential for triggering KSHV lytic reactivation. Despite extensive studies, little is known about whether ORF50 possesses the ability to repress gene expression or has an antagonistic action to cellular transcription factors. Previously, we demonstrated that human oncoprotein MDM2 can promote the degradation of ORF50 protein. Herein, we show that abundant ORF50 expression in cells can conversely downregulate MDM2 expression via repressing both the upstream (P1) and internal (P2) promoters of the MDM2 gene. Deletion analysis of the MDM2 P1 promoter revealed that there were two ORF50-dependent negative response elements located from −102 to −63 and from −39 to +1, which contain Sp1-binding sites. For the MDM2 P2 promoter, the ORF50-dependent negative response element was identified in the region from −110 to −25, which is coincident with the location of two known p53-binding sites. Importantly, we further demonstrated that overexpression of Sp1 or p53 in cells indeed upregulated MDM2 expression; however, coexpression with ORF50 protein remarkably reduced the Sp1- or p53-mediated MDM2 upregulation. Collectively, our findings propose a reciprocal negative regulation between ORF50 and MDM2 and uncover that ORF50 decreases MDM2 expression through repressing Sp1- and p53-mediated transactivation.