MDM2 Research Articles

Mdm2 gene amplification is associated with luminal breast cancer progression in humanized PDX mice and a worse outcome of estrogen receptor positive disease.

Estrogen receptor-positive breast cancer is a highly prevalent but heterogeneous disease among women. Advanced molecular stratification is required to enable individually most efficient treatments based on relevant prognostic and predictive biomarkers. First objective of our study was the hypothesis-driven discovery of biomarkers involved in tumor progression upon xenotransplantation of Luminal breast cancer into humanized mice. The second objective was the marker validation and correlation with the clinical outcome of Luminal breast cancer disease within the GeparTrio trial. An elevated mdm2 gene copy number was associated with enhanced tumor growth and lung metastasis in humanized tumor mice. The viability, proliferation and migration capacity of inherently mdm2 positive breast cancer cells in vitro were significantly reduced upon mdm2 knockdown or anti-mdm2 targeting. An mdm2 gain significantly correlated with a worse DFS and OS of Luminal breast cancer patients, albeit it was also associated with an enhanced preoperative pathological response rate. We provide evidence for an enhanced Luminal breast cancer stratification based on mdm2. Moreover, mdm2 can potentially be utilized as a therapeutic target in the Luminal subtype.

Transcriptomic profiling and pathway analysis of cultured human lung microvascular endothelial cells following ionizing radiation exposure

The vascular system is sensitive to radiation injury, and vascular damage is believed to play a key role in delayed tissue injury such as pulmonary fibrosis. However, the response of endothelial cells to radiation is not completely understood. We examined the response of primary human lung microvascular endothelial cells (HLMVEC) to 10 Gy (1.15 Gy/min) X-irradiation. HLMVEC underwent senescence (80–85%) with no significant necrosis or apoptosis. Targeted RT-qPCR showed increased expression of genes CDKN1A and MDM2 (10–120 min). Western blotting showed upregulation of p2/waf1, MDM2, ATM, and Akt phosphorylation (15 min–72 h). Low levels of apoptosis at 24–72 h were identified using nuclear morphology. To identify novel pathway regulation, RNA-seq was performed on mRNA using time points from 2 to 24 h post-irradiation. Gene ontology and pathway analysis revealed increased cell cycle inhibition, DNA damage response, pro- and anti- apoptosis, and pro-senescence gene expression. Based on published literature on inflammation and endothelial-to-mesenchymal transition (EndMT) pathway genes, we identified increased expression of pro-inflammatory genes and EndMT-associated genes by 24 h. Together our data reveal a time course of integrated gene expression and protein activation leading from early DNA damage response and cell cycle arrest to senescence, pro-inflammatory gene expression, and endothelial-to-mesenchymal transition.

Multiple Time Delays Induced Dynamics of p53 Gene Regulatory Network

p53 dynamics plays an important role in determining cell arrest or apoptosis upon DNA damage response. In this paper, based on a p53 gene regulatory network composed of its core regulator ATM, Mdm2 and Wip1, the effect of multiple time delays in transcription and translation of Mdm2 and Wip1 gene expression on p53 dynamics are investigated through theoretical and numerical analyses. The stability of the positive equilibrium point and the existence of Hopf bifurcation are demonstrated through analyzing the associated characteristic equation of the corresponding linearized system in five cases. Detailed numerical simulations and bifurcation analyses are performed to support the theoretical results. The results show that with the increase of a time delay, the positive equilibrium point becomes unstable, and the p53 dynamics presents an oscillating state. These results reveal that time delay has a significant impact on p53 dynamics and may provide a useful insight into developing anti-cancer therapy.

Abstract P210: MDM2 gene amplification as a predictive biomarker for the MDM2 inhibitor milademetan

Abstract MDM2 is an E3 ubiquitin ligase that plays a critical role in the degradation of the tumor suppressor p53. Milademetan (RAIN-32) is an orally available, small molecule inhibitor of MDM2 that disrupts the MDM2-p53 protein complex thereby restoring p53 expression and activity. Milademetan has demonstrated anti-tumor activity in de-differentiated liposarcoma, a tumor type characterized by MDM2 gene amplification (amp) and WT TP53, in the phase I study of monotherapy milademetan (NCT01877382). Here we investigate the use of MDM2 gene amplification as a predictive biomarker for the selection of patients with advanced cancers who might benefit from milademetan. In this study we evaluated milademetan in MDM2 gene amp cancer models from a variety of tumor types using both in vitro assays, including 2D viability assays and organoid models, as well as in vivo patient-derived xenografts. We employed a mutual exclusivity analysis between MDM2 copy number (CN) and TP53 mutation status using publicly available next generation sequencing data to derive an optimal MDM2 CN threshold for patient selection and present clinical data from patients with MDM2 amp tumors treated with milademetan in the phase 1 study (NCT01877382). Three cell lines, CCFSTTG1 (astrocytoma), DKMG (glioblastoma), and SJSA1 (osteosarcoma), with MDM2 amp were identified and demonstrated inhibition of cell proliferation by milademetan with GI50 <100 nM. Evidence of MDM2 target engagement and activation of p53 was demonstrated through induction of p21 and PUMA, transcriptional targets of p53. Four patient-derived organoid models from diverse cancers (2 lung adenocarcinoma, 1 cholangiocarcinoma, and 1 renall cell carcinoma) were identified with MDM2 amp and WT TP53 and demonstrated differential selectivity compared to non-MDM2 amp models also with WT TP53 (head and neck scquamous cell carcinoma, endometrial carcinoma). Xenograft models from tumor types including gastric, lung adenocarcinoma and osteosarcoma with MDM2 amp showed dose-dependent anti-tumor activity to milademetan in vivo. Induction of MIC-1, a p53 target gene, was observed in vivo following milademetan dosing. An MDM2 CN threshold of ≥ 12 was derived using mutual exclusivity analysis using the AACR Genie dataset across solid tumor types. Using TCGA Pan-Cancer Atlas dataset, we identified 1.1% of cancers that met the criteria of MDM2 CN ≥ 12 and WT TP53. Finally, 3 patients (breast cancer, synovial sarcoma, and small cell lung cancer) with MDM2 CN ≥ 12 were previously enrolled on the U101 study of milademetan, Schedule D (3 days on 11 days off), which was determined to be the dose schedule for future clinical trials, and all 3 patients experienced tumor reduction with 2 patients demonstrating a partial response and 1 confirmed partial response. Milademetan shows evidence of preclinical and clinical anti-tumor activity in genetically selected tumors using MDM2 amp and WT TP53 as selection criteria. A basket study evaluating milademetan in solid tumors with MDM2 CN ≥ 12 and WT TP53 (MANTRA-2) is planned. Citation Format: Vijaya G. Tirunagaru, Mrinal M. Gounder, Prasanna R. Kumar, David S. Hong, Robert C. Doebele. MDM2 gene amplification as a predictive biomarker for the MDM2 inhibitor milademetan [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P210.

Abstract P209: Collaborative crosstalk between two apoptosis pathways drives synergy of dual inhibition of BCL-2/MDM2 in preclinical models of neuroblastoma

Abstract Introduction: The prognosis of patients with neuroblastoma is poor, and novel therapeutic strategies are needed to improve clinical outcomes. Neuroblastoma often exhibits a low TP53 mutation rate and overexpresses MDM2 and BCL-2 genes. Dual targeting of the MDM2-P53 and BCL-2 apoptotic pathways is an attractive treatment strategy (Vernooij et al, Mol Cancer Ther 2021; Dalton et al, Mol Cancer Ther 2021) and is under clinical development using idasanutlin and venetoclax. However, the mechanisms of action (MOAs) of this combination in neuroblastoma are not fully understood. Alrizomadlin (APG-115) is a potent, orally bioactive MDM2 inhibitor. Lisaftoclax (APG-2575) is a novel BCL-2 selective inhibitor. Both agents have shown clinical activity in solid and hematologic malignancies (Tolcher et al, J Clin Oncol 2021:2506; Ailawadhi et al, J Clin Oncol 2021:7502). We investigated the effects of combined alrizomadlin and lisaftoclax treatment in preclinical models of neuroblastoma and examined novel MOAs associated with this combination. Materials and Methods: Antiproliferative activity was measured by CellTiter-Glo luminescent cell viability assay. Apoptosis was evaluated by annexin V/propidium iodide staining and flow cytometry. Meso-Scale Discovery ELISA and western blot analyses characterized the mechanisms of this combination’s synergistic effects. In animal studies, clinically relevant doses of lisaftoclax were employed. A pulsed high-dose regimen of alrizomadlin was used to achieve best efficacy and manage on-target toxicity. Results: In TP53WT neuroblastoma cell lines IMR-32 and SH-SY5Y, the combination of lisaftoclax and alrizomadlin synergistically inhibited proliferation and induced apoptosis, as evidenced by elevations in caspase-3/7, cleaved PARP, and annexin V+ subpopulations. Tumor growth was synergistically inhibited in 3 distinct subcutaneous mouse xenograft tumor models derived from neuroblastoma cell lines or patient tumors. In the cell lines, alrizomadlin treatment upregulated proapoptotic BCL-2 family member expression (NOXA, BAX, and PUMA) and downregulated antiapoptotic BCL-2 family member MCL-1, likely sensitizing cancer cells to lisaftoclax-induced apoptosis. Treatment of these cells with lisaftoclax and alrizomadlin reduced all 3 major BIM-related complexes, thereby increasing free BIM and triggering cellular apoptosis. Lisaftoclax and alrizomadlin downregulated NMYC and its transcription target MDM2, preventing the development of alrizomadlin resistance mediated by a feedback upregulation of MDM2, and inhibition of the MDM2-P53 apoptotic pathway by alrizomadlin primed cancer cells to BCL-2 inhibition. Conclusions: Alrizomadlin synergizes with lisaftoclax to achieve synthetic lethality through a regulated interaction at multiple molecular nodules, and inhibition of BCL-2 apoptotic pathway by lisaftoclax may prevent cancer cells from developing resistance to MDM2-P53 inhibition. These data warrant clinical development of combined alrizomadlin and lisaftoclax treatment in patients with neuroblastoma. Citation Format: Douglas D. Fang, Qiuqiong Tang, Qixin Wang, Yanhui Kong, Na Li, Feng Zhou, Ran Tao, Dajun Yang, Yifan Zhai. Collaborative crosstalk between two apoptosis pathways drives synergy of dual inhibition of BCL-2/MDM2 in preclinical models of neuroblastoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P209.

Computational detection, analysis and interpretations of genomic variants in human diseases associated GENEMDM 2

Most of the mutations described in human MDM2 are tolerated without significantly disrupting the corresponding structural or molecular function. However, some of them are associated with a variety of human diseases, including cancer. Numerous computational methods have been developed to predict the effects of missense single nucleotide variants (SNVs). The non-synonymous single nucleotide polymorphisms affect the function of XRCC1, which impairs the ability to repair DNA and therefore increases the risk of diseases such as cancer. In this study, sequence and structure-based computational tools were used to screen the total listed coding SNPs of the MDM2 gene in order to recognize and describe them. The potential 6 ns SNP of MDM2 were identified from 29 ns SNP by consistent analysis using computational tools PolyPhen 2, SIFT, PANTHER and cSNP. The computational methods were used to systematically classify functional mutations in the regulatory and coding regions that modify the expression and function of the MDM2 enzyme. The HOPE project also made it possible to elaborate the structural effects of the substitutions of amino acids. In silico analysis predicted that rs759244097 is harmful. This study concluded that identifying this SNP will help to determine an individual's cancer susceptibility, prognosis and further treatment. Furthermore, current high-throughput sequencing efforts and the need for extensive interpretation of protein sequence variants requires more efficient and accurate computational methods in the coming years.

Upregulation of DNA repair genes and cell extrusion underpin the remarkable radiation resistance of Trichoplax adhaerens.

Trichoplax adhaerens is the simplest multicellular animal with tissue differentiation and somatic cell turnover. Like all other multicellular organisms, it should be vulnerable to cancer, yet there have been no reports of cancer in T. adhaerens or any other placozoan. We investigated the cancer resistance of T. adhaerens, discovering that they are able to tolerate high levels of radiation damage (218.6 Gy). To investigate how T. adhaerens survive levels of radiation that are lethal to other animals, we examined gene expression after the X-ray exposure, finding overexpression of genes involved in DNA repair and apoptosis including the MDM2 gene. We also discovered that T. adhaerens extrudes clusters of inviable cells after X-ray exposure. T. adhaerens is a valuable model organism for studying the molecular, genetic, and tissue-level mechanisms underlying cancer suppression.

Myxoid pleomorphic liposarcoma—a clinicopathologic, immunohistochemical, molecular genetic and epigenetic study of 12 cases, suggesting a possible relationship with conventional pleomorphic liposarcoma

Myxoid pleomorphic liposarcoma is a recently defined subtype of liposarcoma, which preferentially involves the mediastinum of young patients and shows mixed histological features of conventional myxoid liposarcoma and pleomorphic liposarcoma. While myxoid pleomorphic liposarcoma is known to lack the EWSR1/FUS-DDIT3 fusions characteristic of the former, additional genetic data are limited. To further understand this tumor type, we extensively examined a series of myxoid pleomorphic liposarcomas by fluorescence in situ hybridization (FISH), shallow whole genome sequencing (sWGS) and genome-wide DNA methylation profiling. The 12 tumors occurred in 6 females and 6 males, ranging from 17 to 58 years of age (mean 33 years, median 35 years), and were located in the mediastinum (n = 5), back, neck, cheek and leg, including thigh. Histologically, all cases consisted of relatively, bland, abundantly myxoid areas with a prominent capillary vasculature, admixed with much more cellular and less myxoid foci containing markedly pleomorphic spindled cells, numerous pleomorphic lipoblasts and elevated mitotic activity. Using sWGS, myxoid pleomorphic liposarcomas were found to have complex chromosomal alterations, including recurrent large chromosomal gains involving chromosomes 1, 6–8, 18–21 and losses involving chromosomes 13, 16 and 17. Losses in chromosome 13, in particular loss in 13q14 (including RB1, RCTB2, DLEU1, and ITM2B genes), were observed in 4 out of 8 cases analyzed. Additional FISH analyses confirmed the presence of a monoallelic RB1 deletion in 8/12 cases. Moreover, nuclear Rb expression was deficient in all studied cases. None showed DDIT3 gene rearrangement or MDM2 gene amplification. Using genome-wide DNA methylation profiling, myxoid pleomorphic liposarcomas and conventional pleomorphic liposarcomas formed a common methylation cluster, which segregated from conventional myxoid liposarcomas. While the morphologic, genetic and epigenetic characteristics of myxoid pleomorphic liposarcoma suggest a link with conventional pleomorphic liposarcoma, its distinctive clinical features support continued separate classification for the time being.

Genetic variants in the p53 pathway influence implantation and pregnancy maintenance in IVF treatments using donor oocytes

PurposeSingle-nucleotide polymorphisms (SNPs) in the p53 pathways have shown to play a role in endometrial receptivity and implantation in infertile women undergoing in vitro fertilization (IVF). The present study aimed to assess the influence of these gene variants over pregnancy success through a receptivity model in recipients of egg donation treatments, when factors such as age and quality of the oocytes are standardized.MethodsA nested case–control study was performed on 234 female patients undergoing their first fresh IVF treatment as recipients of donor oocytes. Genotyping of TP53 Arg72Pro (rs1042522), LIF (rs929271), MDM4 (rs1563828), and USP7 (rs1529916) SNPs in the recipients allowed comparison of allele and genotype frequencies and their association with the IVF treatment outcome.ResultsGrouped by genotypes, patients showed differences in IVF outcomes after the embryo transfer. Arg72Pro (rs1042522) gene variant was associated to changes in implantation and clinical pregnancy rates. The polymorphisms USP7 (rs1529916) and MDM4 (rs1563828) were associated to differential ongoing pregnancy rates and variable miscarriage events, respectively.ConclusionsThis study highlights the association between gene polymorphisms related to P53 function and their influence over IVF reproductive outcomes. Arg72Pro variant may influence early events, as lower implantation rates were found in homozygous for Pro72 allele. By contrast, MDM4 (rs1563828) and USP7 (rs1529916) gene variants were associated with the later maintenance of pregnancy.

Systematic Review and Meta-analysis of the Most Common Genetic Mutations in Esophageal Squamous Cell Carcinoma.

Esophageal cancer is the second most common cancer among men and women. There is a need to systematically assess the current evidence to map out the contribution of genetic factors in the development of esophageal squamous cell carcinoma (ESCC). A literature search was carried out on published and unpublished studies up to August 2021 in Medline (PubMed), Embase (Ovid), Scopus, Proquest, Web of Science, and Google scholar. Studies that have reported the frequency of genetic mutations in ESCC were included in this study. A total of 1238 titles were retrieved through searches, and finally, 56 articles, including 8114 samples, met our predefined inclusion criteria. Of the included studies, 31 were conducted in China, 12 in Japan, and the remaining were conducted in various nations, including Brazil, Korea, and Iran. Most of our included studies evaluated the TP53 (n = 37 studies) and PIK3CA (n = 30 studies) gene mutations. TP53 (68.6%; 95% CI: 61.6-74.9), CCND1 (39.3%; 95% CI: 26.2-54.1), MDM2 (24.9%; 95% CI: 9.5-51.0), NOTCH1/2/3 (17.9%; 95% CI: 15.0-21.2), KMT2D (17.4%; 95% CI: 12.4-23.8), CDKN2A (15.0%; 95% CI: 8.1-26.1), PIK3CA (13.8%; 95% CI: 10.3-18.1), FAT1 (13.3%; 95% CI: 11.7-15.0), and EGFR (9.9%; 95% CI: 5.6-17.0) were the most common involved genetic factors in developing ESCC. This systematic review and meta-analysis revealed that more than 10% of ESCC patients had changes in TP53, CCND1, MDM2, NOTCH1/2/3, KMT2D, CDKN2A, PIK3CA, and FAT1 genes, which can highlight their role in developing ESCC. TP53, CCND1, and MDM2 are the most prevalent, demonstrating 68.6%, 39.3%, and 24.9% of the mutations in ESCC patients.

Association between Molecular Genetic Markers of DNA Repair and Cell Cycle Control Genes and Response to Platinum-Based Chemotherapy in Ovarian Cancer Patients.

We analyzed associations of polymorphic markers of DNA repair genes (XRCC1, ERCC2), cell cycle control genes (TP53, MDM2, and CDKN1A), methylation of promoter region, and mutation 5382insC of BRCA1 gene in ovarian cancer with effectiveness of platinumbased chemotherapy assessed by the median of progression-free survival time for markers of DNA repair genes and by relapse risk for all studied markers. An increase in the median of progression-free survival time for carriers of the Gln allele (р=0.025) and Gln/Gln genotype (р=0.022) of the Gln399Arg XRCC1 was observed during the 19-months period after chemotherapy. In carriers of C/C genotype of 5382insC mutation of BRCA1 gene (n=6), no relapses were observed (р=0.035), while 17 of 49 patients without this mutation developed relapses. Of 14 patients with BRCA1 gene function inactivation due to promoter methylation or the presence of the C/C genotype of 5382insC, one relapse was observed (p=0.033). Multivariate analysis revealed an association of markers of the XRCC1, TP53, MDM2 genes, BRCA1 gene inactivation, and type of surgery with the risk of relapse during the follow-up period up to 19 months after the end of chemotherapy (р≤0.0007).

MDM2 (T309G) Gene Polymorphism Determines the Susceptibility of Hepatocellular Carcinoma in Bangladesh

Background: Hepatocellular carcinoma (HCC) is one of the fatal cancer types worldwide, and a variety of genetic factors are considered to be associated with this incidence. MDM2 gene plays a pivotal role in various pathways, which are essential to combat tumor formation. The study aimed to find out the associations of MDM2 (T309G, rs2279744) gene polymorphism with the development of HCC in the Bangladeshi population. Methods: A case-control study on 100 HCC patients and 110 control subjects was conducted. The genotyping of the MDM2 (T309G) gene was done using PCR-RFLP methods. Results: The percentage of TT and GG genotypes were significantly different (p<0.01) among the study subjects. There were four genotyping groups, while the subjects with TT genotypes were considered the reference group. Patients with GG genotypes were at high risk of developing HCC (OR, 3.6; 95 % CI, 1.64–7.80; p<0.01) compared to the control. On the other hand, the association of TG genotypes with HCC was not statistically significant (OR, 1.8; 95 % CI, 0.91–3.40, p>0.05). In addition, patients having either GG or TG genotypes showed higher risk for HCC compared to control group (OR = 2.20; 95% CI = 1.21–4.14; P < 0.05). Conclusion: Our study suggested that the MDM2 gene may have a strong association with the development of HCC, and the GG allele could serve as an essential determinant to identify the higher risk of HCC in the Bangladeshi population.

Genome-Derived Classification Signature for Ampullary Adenocarcinoma to Improve Clinical Cancer Care.

The clinical behavior of ampullary adenocarcinoma varies widely. Targeted tumor sequencing may better define biologically distinct subtypes to improve diagnosis and management. The hidden-genome algorithm, a multilevel meta-feature regression model, was trained on a prospectively sequenced cohort of 3,411 patients (1,001 pancreatic adenocarcinoma, 165 distal bile-duct adenocarcinoma, 2,245 colorectal adenocarcinoma) and subsequently applied to targeted panel DNA-sequencing data from ampullary adenocarcinomas. Genomic classification (i.e., colorectal vs. pancreatic) was correlated with standard histologic classification [i.e., intestinal (INT) vs. pancreatobiliary (PB)] and clinical outcome. Colorectal genomic subtype prediction was primarily influenced by mutations in APC and PIK3CA, tumor mutational burden, and DNA mismatch repair (MMR)-deficiency signature. Pancreatic genomic-subtype prediction was dictated by KRAS gene alterations, particularly KRAS G12D, KRAS G12R, and KRAS G12V. Distal bile-duct adenocarcinoma genomic subtype was most influenced by copy-number gains in the MDM2 gene. Despite high (73%) concordance between immunomorphologic subtype and genomic category, there was significant genomic heterogeneity within both histologic subtypes. Genomic scores with higher colorectal probability were associated with greater survival compared with those with a higher pancreatic probability. The genomic classifier provides insight into the heterogeneity of ampullary adenocarcinoma and improves stratification, which is dictated by the proportion of colorectal and pancreatic genomic alterations. This approach is reproducible with available molecular testing and obviates subjective histologic interpretation.

Molecular Mechanisms of Chemoresistance Induced by Cisplatin in NSCLC Cancer Therapy.

Cancer cells utilise several mechanisms to increase their survival and progression as well as their resistance to anticancer therapy: deregulation of growth regulatory pathways by acquiring grow factor independence, immune system suppression, reducing the expression of antigens activating T lymphocyte cells (mimicry), induction of anti-apoptotic signals to counter the action of drugs, activation of several DNA repair mechanisms and driving the active efflux of drugs from the cell cytoplasm, and epigenetic regulation by microRNAs (miRNAs). Because it is commonly diagnosed late, lung cancer remains a major malignancy with a low five-year survival rate; when diagnosed, the cancer is often highly advanced, and the cancer cells may have acquired drug resistance. This review summarises the main mechanisms involved in cisplatin resistance and interactions between cisplatin-resistant cancer cells and the tumour microenvironment. It also analyses changes in the gene expression profile of cisplatin sensitive vs. cisplatin-resistant non-small cell lung cancer (NSCLC) cellular model using the GSE108214 Gene Expression Omnibus database. It describes a protein-protein interaction network that indicates highly dysregulated TP53, MDM2, and CDKN1A genes as they encode the top networking proteins that may be involved in cisplatin tolerance, these all being upregulated in cisplatin-resistant cells. Furthermore, it illustrates the multifactorial nature of cisplatin resistance by examining the diversity of dysregulated pathways present in cisplatin-resistant NSCLC cells based on KEGG pathway analysis.

Effects of water-soluble components of atmospheric particulates from rare earth mining areas in China on lung cancer cell cycle

BackgroundThis study aims to investigate the effects of water soluble particulate matter (WSPM) on the viability and protein expression profile of human lung adenocarcinoma cell A549 in the Bayou Obo rare earth mining area, and explore the influence of WSPM on the A549 cell cycle.ResultsIt was found that WSPM can inhibit the viability of A549 cells and induce cell arrest in the G2/M phase. Compared with controls, exposure to WSPM10 and WSPM2.5 induced 134 and 116 proteins to be differentially expressed in A549 cells, respectively. In addition, 33 and 31 differentially expressed proteins were further confirmed, and was consistent with the proteomic analysis. The most prominent enrichment in ribosome-associated proteins were presented. When RPL6, RPL13, or RPL18A gene expression was inhibited, A549 cells were arrested in the G1 phase, affecting the expression of Cyclin D1, p21, RB1, Cyclin A2, Cyclin B1, CDC25A, CDK2, CHEK2 and E2F1. Furthermore, the La3+, Ce3+, Nd3+ and F- in WSPM also inhibited the viability of A549 cells. After 24 h of exposure to 2 mM of NaF, A549 cells were also arrested in the G2/M phase, while the other three compounds did not have this effect. These four compounds affected the cell cycle regulatory factors in A549 cells, mainly focusing on effecting the expression of CDK2, CDK4, RB1, ATM, TP53 and MDM2 genes. These results are consistent with the those from WSPM exposure.ConclusionsThese results revealed that WSPM from rare earth mines decreased the viability of A549 cells, and induced cell cycle G2/M phase arrest, and even apoptosis, which may be independent of the NF-κB/MYD88 pathway, and be perceived by the TLR4 receptor. The dysfunction of the cell cycle is correlated to the down-expression of ribosomal proteins (RPs). However, it is not the direct reason for the A549 cell arrest in the G2/M phase. La3+, Ce3+, and F- are probably the main toxic substances in WSPM, and may be regulate the A549 cell cycle by affecting the expression of genes, such as MDM2, RB1, ATM, TP53, E2F1, CDK2 and CDK4. These results indicate the importance for further research into the relationship between APM and lung cancer.

Five MDM4 gene polymorphisms on cancer risk: An updated systematic review and meta-analysis.

The study aims to provide a comprehensive account of the association of five MDM4 gene polymorphisms (rs1380576, rs1563828, rs10900598, rs11801299, and rs4245739) with susceptibility to cancer. A literature search for eligible candidate gene studies published before 27 February 2021 was conducted in PubMed, Medline and Web of Science. The following combinations of main keywords were used: (MDM4 OR MDMX OR HDMX OR mouse double minute 4 homolog) AND (polymorphism OR mutation OR variation OR SNP OR genotype) AND (cancer OR tumor OR neoplasm OR malignancy OR carcinoma OR adenocarcinoma). Potential sources of heterogeneity were sought out via meta-regression, subgroup and sensitivity analysis. Overall, a total of 15 articles with 21,365 cases and 29,280 controls for five polymorphisms of the MDM4 gene were enrolled. In the stratified analysis of rs1380576, we found that Asians might have less susceptibility to cancer. We found that rs4245739 was correlated with a decreased risk of cancer for Asians and breast cancer susceptibility. However, for other polymorphisms, the results showed no significant association with cancer risk. MDM4 rs1380576 polymorphism is negatively associated with the risk of cancer in the Asian population. MDM4 rs4245739 polymorphism is inversely associated with cancer risk for Asians and breast cancer susceptibility.

The utility of fluorescence in situ hybridization (FISH) in determining DNA damage-inducible transcript 3 (DDIT3) amplification in dedifferentiated liposarcomas – an important diagnostic pitfall

Background and objectiveDedifferentiated liposarcoma (DDLPS) is characterized by non-lipogenic sarcoma fields coexisting with adipocyte-rich well-differentiated areas. Amplification of the 12q13–15 region includes the MDM2 and DDIT3 genes. MDM2 amplification is considered a genetic hallmark of DDLPS, while DDIT3 is typically rearranged in myxoid liposarcoma. Recent studies showed that DDIT3 amplification is associated with myxoid liposarcoma-like (LPS-like) morphology in DDLPS. Our study aimed to evaluate the status of MDM2 and DDIT3 by FISH in DDLPS and correlate it with MLPS-like features. Material and methodsSix patients with MLPS-like morphology DDLPS were investigated pathologically, immunohistochemically, and genetically. The control groups of patients with classical DDLPS morphology and well-differentiated liposarcoma (WDLPS) were established and molecularly assessed as well. Fluorescence in situ hybridization (FISH) used in routine diagnostics was performed to determine the status of MDM2 and DDIT3 genes. ResultsThe patient's mean age was 64 (range from 43 to 85 years) with a 5:4 male to female ratio. Tumors were localized retroperitoneally (15) and extra-retroperitoneally (3). All cases demonstrated amplification of the 12q15 region containing MDM2 gene and co-amplification of the 5′ DDIT3 FISH Probe representing DDIT3 telomeric tag. However, we did not find the relation of myxoid LPS-like morphology with DDIT3 amplification as previously reported. ConclusionsThe biopsy material from DDLPS with myxoid areas can be misclassified as myxoid liposarcoma. Indeed, according to the histological image, DDIT3 status may be evaluated first. In these cases, we show that the DDIT3 telomeric tag amplification assessed by FISH, is a common, nonspecific feature, which is also found in classical DDLPS and WDLPS. Therefore, we believe that co-amplification of DDIT3 and MDM2 may be considered a spectrum of the 12q13–15 region amplification due to the specification of FISH methodology.

Pulmonary artery intimal sarcoma – A primeval or rediscovered tumor? A report of 14 new cases with literature review

Pulmonary artery sarcomas (PAS) are rare with many being undifferentiated pleomorphic or spindle cell (UPSC) sarcomas with variable atypia. The term pulmonary artery intimal sarcoma (PAIS) was rarely coined in the early literature and sometimes used for luminal sarcomas. With the advent of immunohistochemistry and molecular genetics, many of these UPSC sarcomas were found to frequently overpress MDM2 and/or CDK4 and PDGFRA with genetic alterations in 12q12–15 and 4q12, where the MDM2, CDK4 and PDGFRA genes are located. These recent developments enabled refinement in diagnosis of PAIS. We diagnosed 14 cases of PAIS (6 males and 8 females, mean age 44 years) in 2015 – 2020 in our institution. Six were initially misdiagnosed as thromboembolism and the remaining pulmonary artery tumors. The tumors were pulmonary artery intraluminal polypoid masses with histology of spindle cell sarcomas exhibiting immunohistochemical positivity for MDM2 (100%) and CDK4 (79%) with MDM2 gene amplification (100%). Ten surgically treated patients fared better than four other biopsy only and not surgically treated patients, who died of disease within 5–11 months. PAIS needs to be differentiated from other spindle cell tumors and those exhibiting MDM2 gene amplification, especially dedifferentiated liposarcoma. The use of biopsy to provide diagnostic material poses a sampling error problem and correlation with clinical, radiologic, histologic, immunophenotypic and genotypic features are essential for accurate diagnosis and early surgical intervention of PAIS.

Clinicopathological and molecular genetic characteristics of adult IDH wild-type diffuse gliomas

Objective: To analyze the clinicopathological and molecular features and prognostic implications of adult isocitrate dehydrogenase wild type (IDH-wt) diffuse gliomas. Methods: A total of 87 cases of adult IDH-wt diffuse gliomas from 2016 to 2020 in Xuanwu Hospital of Capital Medical University were retrospectively collected. The clinicopathological characteristics and prognosis were analyzed. Molecular characteristics were also analyzed using Sanger sequencing and next generation sequencing. Results: There were 53 males and 34 females, aged from 19 to 78 years (mean 53 years). Histopathologically, there were 63 (72.4%) glioblastomas, 16 (18.4%) anaplastic astrocytomas, six (6.9%) diffuse astrocytomas, and one (1.1%) each of anaplastic oligodendrocytoma, and anaplastic oligodendroglioma. Common molecular genetic changes in IDH-wt gliomas included TERT promoter mutation which was found in 60 cases (69.0%); MGMT promoter methylation in 43 cases (49.4%); EGFR mutation in 38 cases (43.7%); PTEN mutation in 35 cases (40.2%) and TP53 mutation in 32 cases (36.8%). In addition, PDGFRA mutation was detected in 17 cases (19.5%), CDK4 amplification in 15 cases (17.2%) and MDM2 amplification in 11 cases (12.6%). In IDH-wt diffuse gliomas, there was no significant difference in the overall survival between TERT promoter, EGFR, PTEN, TP53, PDGFRA, CDK4, MDM2 mutations and the wild-type, since these gene mutations could co-occur in any case (P>0.05). Also there was no significant difference in the overall survival between the WHO grade Ⅱ/Ⅲ gliomas and glioblastoma patients with these gene mutations (P>0.05). Conclusions: TERT promoter, EGFR, PTEN, TP53, PDGFRA, CDK4 and MDM2 gene mutations are common molecular genetic changes in adult IDH-wt gliomas, and are associated with poor prognosis. It is suggested that these genes are potentially useful for predicting the prognosis and should be tested in adult IDH-wt gliomas.

Functional Polymorphisms in the p53 Pathway Genes on the Genetic Susceptibility to Zika Virus Teratogenesis.

Congenital Zika Syndrome (CZS) occurs in up to 42% of individuals exposed to ZIKV prenatally. Deregulation in gene expression and protein levels of components of the p53 signaling pathway, such as p53 and MDM2, due to ZIKV infection has been reported. Here, we evaluate functional polymorphisms in genes of the p53 signaling pathway as risk factors to CZS. Forty children born with CZS and forty-eight children exposed to ZIKV, but born without congenital anomalies were included in this study. Gestational and sociodemographic information as well as the genotypic and allelic frequencies of functional polymorphisms in TP53, MDM2, MIR605 and LIF genes were compared between the two groups. We found children with CZS exposed predominantly in the first trimester and controls in the third trimester (p<0.001). Moreover, children with CZS were predominantly from families with a lower socioeconomic level (p=0.008). We did not find a statistically significant association between the investigated polymorphisms and development of CZS; however, by comparing individuals with CZS and lissencephaly or without lissencephaly, we found a significative difference in the allelic frequencies of the TP53 rs1042522, which is associated with a more potent p53-induced apoptosis (p=0.007). Our findings suggest that the TP53 rs1042522 polymorphism should be better investigate as a genetic risk factor for the development of lissencephaly in children with CZS.