Common polymorphisms in the MDM2 and TP53 genes and the relationship between TP53 mutations and patient outcomes in glioblastomas

Development and validation of an inflammatory response-related prognostic model and immune infiltration analysis in glioblastoma

Background

Despite receiving standard treatment, the prognosis of glioblastoma (GBM) patients is still poor. Considering the heterogeneity of each patient, it is imperative to identify reliable risk model that can effectively predict the prognosis of each GBM patient to guide the personalized treatment.

Methods

Transcriptomic gene expression profiles and corresponding clinical data of GBM patients were downloaded from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. Inflammatory response-related genes were extracted from Gene Set Enrichment Analysis (GSEA) website. Univariate Cox regression analysis was used for prognosis-related inflammatory genes (P<0.05). A polygenic prognostic risk model was constructed using least absolute shrinkage and selection operator (LASSO) Cox regression analysis. Validation was performed through CGGA cohort. Overall survival (OS) was compared by Kaplan-Meier analysis. A nomogram was plotted to accurately predict the prognosis for each patient. GSEA was used for the pathway enrichment analysis. The single sample GSEA (ssGSEA) algorithm was implemented to conduct the immune infiltration analysis. The potential role of oncostatin M receptor (OSMR) in GBM was investigated through the in vitro experiment.

Results

A prognostic risk model consisting of 4 genes (PTPRN, OSMR, MYD88, and EFEMP2) was developed. GBM patients in the high-risk group had worse OS. The time-dependent ROC curves showed an area under the curve (AUC) of 0.782, 0.765, and 0.784 for 1-, 2-, and 3-year survival in TCGA cohort, while the AUC in the CGGA cohort was 0.589, 0.684, and 0.785 at 1, 2, and 3 years, respectively. The risk score, primary-recurrent-secondary (PRS) type, and isocitrate dehydrogenase (IDH) mutation could predict the prognosis of GBM patients well. The nomogram accurately predicted the 1-, 2-, and 3-year OS for each patient. Immune cell infiltration was associated with the risk score and the model could predict immunotherapy responsiveness. The expression of the prognostic gene was correlated with the sensitivity to antitumor drugs. Interference of OSMR inhibited proliferation and migration and promoted apoptosis of GBM cells.

Conclusions

The prognostic model based on 4 inflammatory response-related genes had reliable predictive power to effectively predict clinical outcome in GBM patients and provided the guide for the personalized treatment.

Anticancer Mechanism of Curcumin on Human Glioblastoma

Glioblastoma (GBM) is the most malignant brain tumor and accounts for most adult brain tumors. Current available treatment options for GBM are multimodal, which include surgical resection, radiation, and chemotherapy. Despite the significant advances in diagnostic and therapeutic approaches, GBM remains largely resistant to treatment, with a poor median survival rate between 12 and 18 months. With increasing drug resistance, the introduction of phytochemicals into current GBM treatment has become a potential strategy to combat GBM. Phytochemicals possess multifarious bioactivities with multitarget sites and comparatively marginal toxicity. Among them, curcumin is the most studied compound described as a potential anticancer agent due to its multi-targeted signaling/molecular pathways properties. Curcumin possesses the ability to modulate the core pathways involved in GBM cell proliferation, apoptosis, cell cycle arrest, autophagy, paraptosis, oxidative stress, and tumor cell motility. This review discusses curcumin’s anticancer mechanism through modulation of Rb, p53, MAPK, P13K/Akt, JAK/STAT, Shh, and NF-κB pathways, which are commonly involved and dysregulated in preclinical and clinical GBM models. In addition, limitation issues such as bioavailability, pharmacokinetics perspectives strategies, and clinical trials were discussed.

Replication of GWAS identifies RTEL1, CDKN2A/B, and PHLDB1 SNPs as risk factors in Portuguese gliomas patients

Diffuse gliomas are the most common malignant primary brain tumors and remain incurable. A better knowledge of the tumor etiology is required. Specific single nucleotides polymorphisms (SNPs) rs4977756 (CDKN2A/B), rs6010620 (RTEL1), rs498872 (PHLDB1), rs2736100 (TERT), and rs4295627 (CCDC26) have been associated with glioma susceptibility and are potential risk biomarkers. This study aimed to analyze five SNPs associated with glioma susceptibility, in the Portuguese population. SNPs were genotyped using the Sequenom MassARRAY platform in 127 gliomas and 180 controls. Unconditional logistic regression models were used to calculate odds ratio (OR) and 95% confidence intervals. The false-positive report probability was also assessed. The associations between polymorphisms and survival were evaluated using the log-rank test. It was found that the AG and GG genotypes of the rs4977756 (CDKN2A/B) were associated with an increased risk of gliomas (OR 1.85 and OR 2.38) and glioblastomas (OR 2.77 and OR 3.94). The GA genotype of the rs6010620 (RTEL1) was associated with a decreased risk of glioblastomas (OR 0.45). We also observed that the GA genotype of the rs498872 (PHLDB1) was associated with an increased risk of gliomas (OR 2.92) and glioblastomas (OR 2.39). No significant risk associations were found for the rs2736100 (TERT) and rs4295627 (CCDC26). In addition, the genotype AA of the rs498872 (PHLDB1) was associated with poor overall survival of gliomas patients (AA vs. GA, p = 0.037). The rs6010620 (RTEL1), rs4977756 (CDKN2A/B), and rs498872 (PHLDB1) are associated with glioma risk in the Portuguese population and these data may contribute to understanding gliomas etiology.

Clinical and Molecular Characteristics of Thalamic Gliomas: Retrospective Report of 26 Cases

OBJECTIVE

Thalamic glioma is a type of midline glioma with poor outcomes. In the present study, we investigated the clinical and molecular features of thalamic gliomas in Chinese patients.

METHODS

The data from 26 patients with thalamic glioma who had undergone surgery at Shanghai Huashan Hospital from January 2011 to August 2015 were retrospectively analyzed. Various clinical and molecular factors were evaluated to explore their effects on prognosis. H3K27M mutation status and its association with relevant molecular factors were also investigated.

RESULTS

The mean age of the patients was 38.88 years, and no significant difference was found in sex. The most common initial symptoms were headaches (38.46%; 10 of 26) and motor deficits (30.77%; 8 of 26). The H3K27M mutation was identified in 12 patients, and mutant thalamic glioma showed less frequent O-6-methylguanine DNA methyltransferase (MGMT) promoter methylation compared with the wild-type group (P = 0.015; χ¹ test). Multivariate analysis showed that the H3K27M mutation was an independent unfavorable prognostic factor for overall survival. MGMT promoter unmethylation and the TP53 mutation were identified as negative prognostic factors for progression-free survival.

CONCLUSIONS

Our results revealed the clinical and molecular characteristics of thalamic glioma in China. Our data have shown the absence of MGMT promoter methylation in H3K27M mutant thalamic glioma, validating it as a hallmark of H3K27M mutant gliomas. In addition, H3K27M mutation was identified as the sole unfavorable prognostic factor on overall survival. MGMT promoter unmethylation and TP53 mutation were identified as independent prognostic factors for progression-free survival.

Genetic variants of vascular endothelial growth factor predict risk and survival of gliomas

The vascular endothelial growth factor regulates angiogenesis that is increased in glioma. VEGF polymorphisms are thought to modulate vascular endothelial growth factor plasma levels and therefore may be implicated in glioma risk. We aimed to clarify the role of VEGF and von Willebrand factor polymorphisms in glioma susceptibility and prognosis. A case-control study of 126 glioma patients and 180 cancer-free controls was performed. Using Sequenom MassARRAY platform, 11 VEGF and 1 VWF polymorphisms were genotyped. Unconditional multivariate logistic regression models were used to calculate odds ratios and 95% confidence intervals. The associations between polymorphisms and survival were evaluated using a Cox regression model. Bonferroni's adjustment was used to correct for multiple testing. The VEGF polymorphism rs833061 was strongly associated with increased risk for glioma (odds ratio = 164.85) and glioblastoma (odds ratio = 155.66), confirmed after Bonferroni correction. Also, the VEGF polymorphisms rs3024994, rs2010963, and particularly the homozygous carriers of rs1005230 were associated with a worse prognosis for glioma and glioblastoma. Our data support a role of VEGF and VWF polymorphisms as glioma biomarkers, with additional potential relevance for molecular stratification of patients for anti-angiogenic therapies.

Sex-specific clinicopathological significance of novel (Frizzled-7) and established (MGMT, IDH1) biomarkers in glioblastoma

Background

The Wnt receptor Frizzled-7 (FZD7) promotes tumor progression and can be currently targeted by monoclonal antibody therapy. Here, we determined the prognostic value of FZD7 for the overall survival of glioblastoma (GBM) patients, both as individual marker and taken in combination with the previously-described markers MGMT and IDH1. Additionally, we tested whether these markers (alone or in combination) exhibited sex-specific differences.

Results

High levels of FZD7 (FZD7^high) associated with shorter survival in GBM patients; however, FZD7^high was a significant predictor of poor survival only in male patients. Mutation of IDH1 significantly associated with longer survival in male but not female patients. Methylated MGMT promoter significantly associated with longer survival only in female patients. Combination of FZD7 with MGMT enhanced the prognostic accuracy and abrogated the sex differences observed upon single marker analysis. Combination of FZD7 with IDH1 was a significant predictor of survival in male GBM patients only.

Materials and Methods

Three independent cohorts of patients with primary GBM (n=120, n=108 and n=105, respectively) were included in this study. FZD7 and IDH1 were assessed by immunohistochemistry in tissue microarrays. MGMT promoter methylation was determined by methylation-specific polymerase chain reaction. Survival analysis was performed by Kaplan-Meier estimate, log-rank test and Cox proportional hazard regression.

Conclusions

Our study identifies novel individual and combination markers with prognostic and, possibly, therapeutic relevance in GBM. Furthermore, our findings substantiate the importance of sexual dimorphism in this type of cancer.

Insights From Molecular Profiling of Adult Glioma

The comprehensive molecular profiling of cancer has resulted in new insights into the biology and classification of numerous tumor types. In the case of primary brain tumors that commonly affect adults, an emerging set of disease-defining biomarker sets is reshaping existing diagnostic entities that had previously been defined on the basis of their microscopic appearance. Substantial progress has been made in this regard for common primary brain tumors in adults, especially diffuse gliomas, where large-scale profiling efforts have led to the incorporation of highly prevalent molecular alterations that promote a biologically based classification as an adjunct to the traditional histopathologic approach. The growing awareness that histologically indistinguishable tumors can be divided into more precise and biologically relevant subgroups has demanded a more global routine approach to biomarker assessment. These considerations have begun to intersect with the decreasing costs and availability of genome-wide analysis tools and, thus, incorporation into routine practice. We review how molecular profiling already has led to an evolution in the classification of brain tumors. In addition, we discuss the likely trajectory of incorporation of global molecular profiling platforms into the routine clinical classification of adult brain tumors.

The prognostic value of MGMT promoter methylation in glioblastoma: A meta-analysis of clinical trials

The DNA repair protein O6-Methylguanine-DNA methyltransferase (MGMT) is suggested to be associated with resistance to alkylating agents such as Temozolomide which is being used in treatment of patients with glioblastoma (GBM). Therefore, we evaluated the associations between MGMT promoter methylation and prognosis of patients with glioblastoma (GBM). Data were extracted from publications in Embase, PubMed, and the Cochrane Library. Data on overall survival (OS), progression-free survival (PFS), and MGMT methylation status were obtained and 4,097 subjects were enrolled. Data from 34 studies showed that MGMT methylated patients had better OS, compared to GBM unmethylated patients (pooled HRs, 0.494; 95%CI 0.412-0.591; p = 0.001). Meta-analysis of 10 eligible studies reporting on PFS, demonstrated that MGMT promoter methylation was not significantly associated with better PFS (pooled HRs, 0.653; 95%CI 0.414-1.030; p = 0.067). GBM patients with MGMT methylation were associated with longer overall survival, although this effect was not detected for PFS. Moreover, we performed further analysis in patients underwent a comprehensive imaging evaluation. This data showed a significant association with better OS and PFS, although further studies are warranted to assess the value of emerging marker in prospective setting in patients with glioblastoma as a risk stratification biomarker in clinical management of the patients.

Stimulation of prolactin receptor induces STAT-5 phosphorylation and cellular invasion in glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in humans and is characterized with poor outcome. In this study, we investigated components of prolactin (Prl) system in cell models of GBM and in histological tissue sections obtained from GBM patients. Expression of Prolactin receptor (PrlR) was detected at high levels in U251-MG, at low levels in U87-MG and barely detectable in U373 cell lines and in 66% of brain tumor tissues from 32 GBM patients by immunohistochemical technique. In addition, stimulation of U251-MG and U87-MG cells but not U373 with Prl resulted in increased STAT5 phosphorylation and only in U251-MG cells with increased cellular invasion. Furthermore, STAT5 phosphorylation and cellular invasion induced in Prl stimulated cells were significantly reduced by using a Prl receptor antagonist that consists of Prl with four amino acid replacements. We conclude that Prl receptor is expressed at different levels in the majority of GBM tumors and that blocking of PrlR in U251-MG cells significantly reduce cellular invasion.

Molecular and Genomic Alterations in Glioblastoma Multiforme

In recent years, important advances have been achieved in the understanding of the molecular biology of glioblastoma multiforme (GBM); thus, complex genetic alterations and genomic profiles, which recurrently involve multiple signaling pathways, have been defined, leading to the first molecular/genetic classification of the disease. In this regard, different genetic alterations and genetic pathways appear to distinguish primary (eg, EGFR amplification) versus secondary (eg, IDH1/2 or TP53 mutation) GBM. Such genetic alterations target distinct combinations of the growth factor receptor-ras signaling pathways, as well as the phosphatidylinositol 3-kinase/phosphatase and tensin homolog/AKT, retinoblastoma/cyclin-dependent kinase (CDK) N2A-p16(INK4A), and TP53/mouse double minute (MDM) 2/MDM4/CDKN2A-p14(ARF) pathways, in cells that present features associated with key stages of normal neurogenesis and (normal) central nervous system cell types. This translates into well-defined genomic profiles that have been recently classified by The Cancer Genome Atlas Consortium into four subtypes: classic, mesenchymal, proneural, and neural GBM. Herein, we review the most relevant genetic alterations of primary versus secondary GBM, the specific signaling pathways involved, and the overall genomic profile of this genetically heterogeneous group of malignant tumors.

A functional SNP in the MDM2 promoter mediates E2F1 affinity to modulate cyclin D1 expression in tumor cell proliferation

BACKGROUND

The MDM2 oncogene, a negative regulator of p53, has a functional polymorphism in the promoter region (SNP309) that is associated with multiple kinds of cancers including non-melanoma skin cancer. SNP309 has been shown to associate with accelerated tumor formation by increasing the affinity of the transcriptional activator Sp1. It remains unknown whether there are other factors involved in the regulation of MDM2 transcription through a trans-regulatory mechanism.

METHODS

In this study, SNP309 was verified to be associated with overexpression of MDM2 in tumor cells. Bioinformatics predicts that the T to G substitution at SNP309 generates a stronger E2F1 binding site, which was confirmed by ChIP and luciferase assays.

RESULTS

E2F1 knockdown downregulates the expression of MDM2, which confirms that E2F1 is a functional upstream regulator. Furthermore, tumor cells with the GG genotype exhibited a higher proliferation rate than TT, correlating with cyclin D1 expression. E2F1 depletion significantly inhibits the proliferation capacity and downregulates cyclin D1 expression, especially in GG genotype skin fibroblasts. Notably, E2F1 siRNA effects could be rescued by cyclin D1 overexpression.

CONCLUSION

Taken together, a novel modulator E2F1 was identified as regulating MDM2 expression dependent on SNP309 and further mediates cyclin D1 expression and tumor cell proliferation. E2F1 might act as an important factor for SNP309 serving as a rate-limiting event in carcinogenesis.

Analysis of Tp53 codon 72 polymorphisms, Tp53 mutations, and HPV infection in cutaneous squamous cell carcinomas

Background

Non-melanoma skin cancers are one of the most common human malignancies accounting for 2–3% of tumors in the US and represent a significant health burden. Epidemiology studies have implicated Tp53 mutations triggered by UV exposure, and human papilloma virus (HPV) infection to be significant causes of non-melanoma skin cancer. However, the relationship between Tp53 and cutaneous HPV infection is not well understood in skin cancers. In this study we assessed the association of HPV infection and Tp53 polymorphisms and mutations in lesional specimens with squamous cell carcinomas.

Methods

We studied 55 cases of histologically confirmed cutaneous squamous cell carcinoma and 41 controls for the presence of HPV infection and Tp53 genotype (mutations and polymorphism).

Results

We found an increased number of Tp53 mutations in the squamous cell carcinoma samples compared with perilesional or control samples. There was increased frequency of homozygous Tp53-72R polymorphism in cases with squamous cell carcinomas, while the Tp53-72P allele (Tp53-72R/P and Tp53-72P/P) was more frequent in normal control samples. Carcinoma samples positive for HPV showed a decreased frequency of Tp53 mutations compared to those without HPV infection. In addition, carcinoma samples with a Tp53-72P allele showed an increased incidence of Tp53 mutations in comparison carcinomas samples homozygous for Tp53-72R.

Conclusions

These studies suggest there are two separate pathways (HPV infection and Tp53 mutation) leading to cutaneous squamous cell carcinomas stratified by the Tp53 codon-72 polymorphism. The presence of a Tp53-72P allele is protective against cutaneous squamous cell carcinoma, and carcinoma specimens with Tp53-72P are more likely to have Tp53 mutations. In contrast Tp53-72R is a significant risk factor for cutaneous squamous cell carcinoma and is frequently associated with HPV infection instead of Tp53 mutations. Heterozygosity for Tp53-72R/P is protective against squamous cell carcinomas, possibly reflecting a requirement for both HPV infection and Tp53 mutations.

TP53 codon 72 polymorphism and glioma risk: A meta-analysis

TP53 codon 72 polymorphism has been reported to affect regulatory networks central to glioma development. Although a number of published studies noted the association between TP53 codon 72 polymorphism and glioma risk, their conclusions were inconsistent. A meta-analysis was used to assess the possible association between TP53 codon 72 polymorphism and glioma risk. The PubMed databases were searched, relevant articles were identified and data were retrieved based on the inclusion criteria. The odds ratio (OR) and 95% confidence interval (95% CI) were determined on the pooled dataset. We retrieved eight different studies including 2,260 glioma cases and 3,506 controls. However, no association was found between the TP53 codon 72 polymorphism and glioma risk regarding the comparison between glioma cases and the controls. By further stratification based on criteria such as tumor grade, and the geographical location of the patients and the relevant controls, we found a significant association in the subgroup of patients with high-grade glioma in Europeans compared to controls in two models of TP53 codon 72 polymorphism, which include the dominant model [C/C + G/C vs. G/G: OR=1.35, 95% CI (1.14, 1.59), P=0.0005, P(h)=0.13] and the additive model [C allele vs. G allele: OR=1.16, 95% CI (1.02, 1.33), P=0.03, P(h)=0.37]. Our analysis suggests that TP53 codon 72 polymorphism is associated with an increased risk of high-grade glioma development in Europeans.

The pro-migratory and pro-invasive role of the procoagulant tissue factor in malignant gliomas

During the infiltration process, glioma cells are known to migrate along preexisting anatomical structures such as blood vessels, axonal fiber tracts and the subependymal space, thereby widely invading surrounding CNS tissue. This phenomenon represents a major obstacle for the clinical treatment of these tumours. Several extracellular key factors and intracellular signaling pathways have been previously linked to the highly aggressive, invasive phenotype observed in malignant gliomas. The glioblastoma (GBM) which is the most malignant form of these tumors, is histologically characterized by areas of tumor necroses and pseudopalisading cells, the latter likely representing tumor cells actively migrating away from the hypoxic-ischemic core of the tumor. It is believed that intravascular thromboses play a major role in the emergence of hypoxia and intratumoral necroses in GBMs. One of the most highly upregulated prothrombotic factor in malignant gliomas is tissue factor (TF), a 47 kDa type I transmembrane protein belonging to the cytokine receptor superfamily. In a recent study, we provided evidence that TF/FVIIa signaling via the protease-activated receptor 2 (PAR-2) promotes cell growth, migration and invasion of glioma cells. In this point of view article we outline the key molecular players involved in migration and invasion of gliomas, highlight the potential role of TF for the pro-migratory and pro-invasive phenotype of these tumors and discuss the underlying mechanisms on the cellular level and in the tumor microenvironment.

Molecular alterations in glioblastoma: potential targets for immunotherapy

Glioblastoma is the most common and deadly brain tumor, possibly arising from genetic and epigenetic alterations in normal astroglial cells. Multiple cytogenetic, chromosomal, and genetic alterations have been identified in glioblastoma, with distinct expression of antigens (Ags) and biomarkers that may alter therapeutic potential of this aggressive cancer. Current therapy consists of surgical resection, followed by radiation therapy and chemotherapy. In spite of these treatments, the prognosis for glioblastoma patients is poor. Although recent studies have focused on the development of novel immunotherapeutics against glioblastoma, little is known about glioblastoma-specific immune responses. A better understanding of the molecular interactions among glioblastoma tumors, host immune cells, and the tumor microenvironment may give rise to novel integrated approaches for the simultaneous control of tumor escape pathways and the activation of antitumor immune responses. This review provides a detailed overview concerning genetic alterations in glioblastoma, their effects on Ag and biomarker expression, and the future design of chemoimmunotherapeutics against glioblastoma.

TP53 mutations in human cancers: origins, consequences, and clinical use

Somatic mutations in the TP53 gene are one of the most frequent alterations in human cancers, and germline mutations are the underlying cause of Li-Fraumeni syndrome, which predisposes to a wide spectrum of early-onset cancers. Most mutations are single-base substitutions distributed throughout the coding sequence. Their diverse types and positions may inform on the nature of mutagenic mechanisms involved in cancer etiology. TP53 mutations are also potential prognostic and predictive markers, as well as targets for pharmacological intervention. All mutations found in human cancers are compiled in the IARC TP53 Database (http://www-p53.iarc.fr/). A human TP53 knockin mouse model (Hupki mouse) provides an experimental model to study mutagenesis in the context of a human TP53 sequence. Here, we summarize current knowledge on TP53 gene variations observed in human cancers and populations, and current clinical applications derived from this knowledge.

Genetic alterations and signaling pathways in the evolution of gliomas

Gliomas are the most common primary brain tumors. They account for more than 70% of all neoplasms of the central nervous system and vary considerably in morphology, location, genetic alterations, and response to therapy. Most frequent and malignant are glioblastomas. The vast majority (>90%) develops rapidly after a short clinical history and without evidence of a less malignant precursor lesion (primary or de novo glioblastoma). Secondary glioblastomas develop more slowly through progression from low-grade or anaplastic astrocytoma. These glioblastoma subtypes constitute distinct disease entities that affect patients of different age, develop through distinct genetic pathways, show different RNA and protein expression profiles, and may differ in their response to radio- and chemotherapy. Recently, isocitrate dehydrogenase 1 (IDH1) mutations have been identified as a very early and frequent genetic alteration in the pathway to secondary glioblastomas as well as that in oligodendroglial tumors, providing the first evidence that low-grade astrocytomas and oligodendrogliomas may share common cells of origin. In contrast, primary glioblastomas very rarely contain IDH1 mutations, suggesting that primary and secondary glioblastomas may originate from different progenitor cells, despite the fact that they are histologically largely indistinguishable. In this review, we summarize the current status of genetic alterations and signaling pathways operative in the evolution of astrocytic and oligodendroglial tumors.

p53 polymorphisms: cancer implications

The normal functioning of p53 is a potent barrier to cancer. Tumour-associated mutations in TP53, typically single nucleotide substitutions in the coding sequence, are a hallmark of most human cancers and cause dramatic defects in p53 function. By contrast, only a small fraction, if any, of the >200 naturally occurring sequence variations (single nucleotide polymorphisms, SNPs) of TP53 in human populations are expected to cause measurable perturbation of p53 function. Polymorphisms in the TP53 locus that might have cancer-related phenotypical manifestations are the subject of this Review. Polymorphic variants of other genes in the p53 pathway, such as MDM2, which might have biological consequences either individually or in combination with p53 variants are also discussed.