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Human glioblastoma cells: Tet-on(mutant p53 R175H expression) vs Tet-off(p53-null)

ABSTRACT: TP53 R175H mutation is one of the most common mutations in human cancers and cancer cells with this mutation stably express R175H protein in the nucleus. To identify the synthetic lethal gene interacted with the R175H, we conducted the high throughput screening by using tetracyclin inducible R175H expression system in SF126 cells and comprehensive shRNA library carried by lenti virus. We identified 906 candidate gene suppressions that may lead to accelerated cell growth inhibition under the presence of R175H. Inhibitor of differentiation 1 (ID1) was one of the candidate genes and suppression of ID1 by siRNA resulted in acceleration of growth inhibition of cell lines expressing endogenous R175H but not in TP53 null cell lines. The transient expression of R175H in TP53 null cell lines and suppression of ID1 and/or TP53 R175H in cell lines with endogenous R175H revealed that the cell growth inhibition by ID1 suppression was dependent on R175H expression but not other common p53 mutants (R273H). Flow cytometric (FACS) analysis exhibited that ID1 suppression resulted in G1 arrest and the arrest was accelerated by suppression of R175H. In conclusion, ID1 is a synthetic lethal gene interacted with R175H and is considered to be a novel molecular target of cancer therapy for R175H expressing cells. R175H expression(Tet-on) group was labeled by Cy5, and p53-null(Tet-off) group was labeled by Cy3. Three independent experiments were conducted (We have triplicate data).

ORGANISM(S): Homo sapiens

SUBMITTER: hiroo imai

PROVIDER: S-ECPF-GEOD-33362 | biostudies-other |

REPOSITORIES: biostudies-other

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Human glioblastoma cells: Tet-on(mutant p53 R175H expression) vs Tet-off(p53-null)

Project description:TP53 R175H mutation is one of the most common mutations in human cancers and cancer cells with this mutation stably express R175H protein in the nucleus. To identify the synthetic lethal gene interacted with the R175H, we conducted the high throughput screening by using tetracyclin inducible R175H expression system in SF126 cells and comprehensive shRNA library carried by lenti virus. We identified 906 candidate gene suppressions that may lead to accelerated cell growth inhibition under the presence of R175H. Inhibitor of differentiation 1 (ID1) was one of the candidate genes and suppression of ID1 by siRNA resulted in acceleration of growth inhibition of cell lines expressing endogenous R175H but not in TP53 null cell lines. The transient expression of R175H in TP53 null cell lines and suppression of ID1 and/or TP53 R175H in cell lines with endogenous R175H revealed that the cell growth inhibition by ID1 suppression was dependent on R175H expression but not other common p53 mutants (R273H). Flow cytometric (FACS) analysis exhibited that ID1 suppression resulted in G1 arrest and the arrest was accelerated by suppression of R175H. In conclusion, ID1 is a synthetic lethal gene interacted with R175H and is considered to be a novel molecular target of cancer therapy for R175H expressing cells.

2011-11-02 | GSE33362 | GEO

Human glioblastoma cells: Tet-on(mutant p53 R175H expression) vs Tet-off(p53-null)

2011-11-02 | E-GEOD-33362 | biostudies-arrayexpress

Cyclophilin B supports Myc and mutant p53-dependent survival of glioblastoma multiforme cells.

Project description:Glioblastoma multiforme is an aggressive, treatment-refractory type of brain tumor for which effective therapeutic targets remain important to identify. Here, we report that cyclophilin B (CypB), a prolyl isomerase residing in the endoplasmic reticulum (ER), provides an essential survival signal in glioblastoma multiforme cells. Analysis of gene expression databases revealed that CypB is upregulated in many cases of malignant glioma. We found that suppression of CypB reduced cell proliferation and survival in human glioblastoma multiforme cells in vitro and in vivo. We also found that treatment with small molecule inhibitors of cyclophilins, including the approved drug cyclosporine, greatly reduced the viability of glioblastoma multiforme cells. Mechanistically, depletion or pharmacologic inhibition of CypB caused hyperactivation of the oncogenic RAS-mitogen-activated protein kinase pathway, induction of cellular senescence signals, and death resulting from loss of MYC, mutant p53, Chk1, and Janus-activated kinase/STAT3 signaling. Elevated reactive oxygen species, ER expansion, and abnormal unfolded protein responses in CypB-depleted glioblastoma multiforme cells indicated that CypB alleviates oxidative and ER stresses and coordinates stress adaptation responses. Enhanced cell survival and sustained expression of multiple oncogenic proteins downstream of CypB may thus contribute to the poor outcome of glioblastoma multiforme tumors. Our findings link chaperone-mediated protein folding in the ER to mechanisms underlying oncogenic transformation, and they make CypB an attractive and immediately targetable molecule for glioblastoma multiforme therapy.

| S-EPMC3935234 | biostudies-literature

Glioblastoma cells inhibit astrocytic p53-expression favoring cancer malignancy.

Project description:The tumor microenvironment has a dynamic and usually cancer-promoting function during all tumorigenic steps. Glioblastoma (GBM) is a fatal tumor of the central nervous system, in which a substantial number of non-tumoral infiltrated cells can be found. Astrocytes neighboring these tumor cells have a particular reactive phenotype and can enhance GBM malignancy by inducing aberrant cell proliferation and invasion. The tumor suppressor p53 has a potential non-cell autonomous function by modulating the expression of secreted proteins that influence neighbor cells. In this work, we investigated the role of p53 on the crosstalk between GBM cells and astrocytes. We show that extracellular matrix (ECM) from p53(+/-) astrocytes is richer in laminin and fibronectin, compared with ECM from p53(+/+) astrocytes. In addition, ECM from p53(+/-) astrocytes increases the survival and the expression of mesenchymal markers in GBM cells, which suggests haploinsufficient phenotype of the p53(+/-) microenvironment. Importantly, conditioned medium from GBM cells blocks the expression of p53 in p53(+/+) astrocytes, even when DNA was damaged. These results suggest that GBM cells create a dysfunctional microenvironment based on the impairment of p53 expression that in turns exacerbates tumor endurance.

| S-EPMC4216902 | biostudies-literature

Modulation of gene expression in U251 glioblastoma cells by binding of mutant p53 R273H to intronic and intergenic sequences.

Project description:Missense point mutations in the TP53 gene are frequent genetic alterations in human tumor tissue and cell lines derived thereof. Mutant p53 (mutp53) proteins have lost sequence-specific DNA binding, but have retained the ability to interact in a structure-selective manner with non-B DNA and to act as regulators of transcription. To identify functional binding sites of mutp53, we established a small library of genomic sequences bound by p53(R273H) in U251 human glioblastoma cells using chromatin immunoprecipitation (ChIP). Mutp53 binding to isolated DNA fragments confirmed the specificity of the ChIP. The mutp53 bound DNA sequences are rich in repetitive DNA elements, which are dispersed over non-coding DNA regions. Stable down-regulation of mutp53 expression strongly suggested that mutp53 binding to genomic DNA is functional. We identified the PPARGC1A and FRMD5 genes as p53(R273H) targets regulated by binding to intronic and intra-genic sequences. We propose a model that attributes the oncogenic functions of mutp53 to its ability to interact with intronic and intergenic non-B DNA sequences and modulate gene transcription via re-organization of chromatin.

| S-EPMC2655687 | biostudies-literature

Modulation of gene expression in U251 glioblastoma cells by binding of mutant p53 to intronic and intergenic sequences

Project description:Missense point mutations in the TP53 gene are frequent genetic alterations in human tumor tissue and cell lines derived thereof. Mutant p53 (mutp53) proteins have lost sequence-specific DNA binding, but have retained the ability to interact in a structure-selective manner with non-B DNA and to act as regulators of transcription. To identify functional binding sites of mutp53, we established a small library of genomic sequences bound by p53R273H in U251 human glioblastoma cells using chromatin immunoprecipitation (ChIP). Mutp53 binding to isolated DNA fragments confirmed the specificity of the ChIP. The mutp53 bound DNA sequences are rich in repetitive DNA elements, which are dispersed over non-coding DNA regions. Stable down-regulation of mutp53 expression strongly suggested that mutp53 binding to genomic DNA is functional. We identified the PPARGC1A and FRMD5 genes as p53R273H targets regulated by binding to intronic and intra-genic sequences. We propose a model that attributes the oncogenic functions of mutp53 to its ability to interact with intronic and intergenic non-B DNA sequences and modulate gene transcription via re-organization of chromatin. For the study of the consequences of mutant p53 (R273H) knockdown on gene expression, total RNA from parental U251 glioblastoma cells and UsiA12 clone was prepared from two independent cell culture experiments (biological replicates) and processed for microarray-based profiling of gene expression. UsiA12 clone was derived from the U251 cells transfected with the pSuper-p53 and pCI-neo vectors.

| S-ECPF-GEOD-13991 | biostudies-other

Pharmacogenomic profiling and pathway analyses identify MAPK-dependent migration as an acute response to SN38 in p53 null and p53-mutant colorectal cancer cells.

Project description:The topoisomerase I inhibitor irinotecan is used to treat advanced colorectal cancer and has been shown to have p53-independent anticancer activity. The aim of this study was to identify the p53-independent signaling mechanisms activated by irinotecan. Transcriptional profiling of isogenic HCT116 p53 wild-type and p53 null cells was carried out following treatment with the active metabolite of irinotecan, SN38. Unsupervised analysis methods showed that p53 status had a highly significant impact on gene expression changes in response to SN38. Pathway analysis indicated that pathways involved in cell motility [adherens junction, focal adhesion, mitogen-activated protein kinase (MAPK), and regulation of the actin cytoskeleton] were significantly activated in p53 null cells, but not p53 wild-type cells, following SN38 treatment. In functional assays, SN38 treatment increased the migratory potential of p53 null and p53-mutant colorectal cancer cell lines, but not p53 wild-type lines. Moreover, p53 null SN38-resistant cells were found to migrate at a faster rate than parental drug-sensitive p53 null cells, whereas p53 wild-type SN38-resistant cells failed to migrate. Notably, cotreatment with inhibitors of the MAPK pathway inhibited the increased migration observed following SN38 treatment in p53 null and p53-mutant cells. Thus, in the absence of wild-type p53, SN38 promotes migration of colorectal cancer cells, and inhibiting MAPK blocks this potentially prometastatic adaptive response to this anticancer drug.

| S-EPMC3428848 | biostudies-literature

In vitro modeling of glioblastoma initiation using PDGF-AA and p53-null neural progenitors.

Project description:BackgroundImagining ways to prevent or treat glioblastoma (GBM) has been hindered by a lack of understanding of its pathogenesis. Although overexpression of platelet derived growth factor with two A-chains (PDGF-AA) may be an early event, critical details of the core biology of GBM are lacking. For example, existing PDGF-driven models replicate its microscopic appearance, but not its genomic architecture. Here we report a model that overcomes this barrier to authenticity.MethodsUsing a method developed to establish neural stem cell cultures, we investigated the effects of PDGF-AA on subventricular zone (SVZ) cells, one of the putative cells of origin of GBM. We microdissected SVZ tissue from p53-null and wild-type adult mice, cultured cells in media supplemented with PDGF-AA, and assessed cell viability, proliferation, genome stability, and tumorigenicity.ResultsCounterintuitive to its canonical role as a growth factor, we observed abrupt and massive cell death in PDGF-AA: wild-type cells did not survive, whereas a small fraction of null cells evaded apoptosis. Surviving null cells displayed attenuated proliferation accompanied by whole chromosome gains and losses. After approximately 100 days in PDGF-AA, cells suddenly proliferated rapidly, acquired growth factor independence, and became tumorigenic in immune-competent mice. Transformed cells had an oligodendrocyte precursor-like lineage marker profile, were resistant to platelet derived growth factor receptor alpha inhibition, and harbored highly abnormal karyotypes similar to human GBM.ConclusionThis model associates genome instability in neural progenitor cells with chronic exposure to PDGF-AA and is the first to approximate the genomic landscape of human GBM and the first in which the earliest phases of the disease can be studied directly.

| S-EPMC7594559 | biostudies-literature

Mutant p53 gain of function induces HER2 over-expression in cancer cells.

Project description:BackgroundHER2 over-expression is related with a poor prognosis in patients with invasive breast cancer tumors. Clinical associations have reported that somatic mutations of p53 more frequently detected in cases of sporadic breast cancer of the HER2 subtypes, besides a high percentage of HER2-amplifying tumors carry germline mutations of p53. The mechanisms responsible for the acquisition of oncogenic functions of p53 mutant proteins (mtp53), known as Gain of Function (GOF), over HER2 expression have not been reported. The objective of this study was to evaluate a possible relationship between p53 mutants and HER2 regulation.MethodsHER2 expression (transcription and protein), as well as HER2 protein stabilization have been evaluated after inducing or silencing of p53 mutants' expression in cell lines. Finally, we evaluated the interaction of the p53 mutants over the HER2 receptor promoter.ResultsHigher HER2 expression in cell lines harboring endogenous mtp53 compared with wt or null expression of p53 cell lines. Transfection of p53 mutants (R248Q and R273C) in cell lines increased the expression of HER2. Silencing of p53 mutants, decrease HER2 expression. The p53 mutants R248Q and R273C significantly increase the luciferase activity on the HER2 promoter, and both mutants also promote acetylation of H3 and H4 histones binding in it.ConclusionsThese findings show for the first time that p53 mutants induce over-expression of HER2 at transcriptional level of the HER2 protein. Our results could have clinical implications in breast cancer and other types of cancer where HER2 is over-expressed and used as a therapy target.

| S-EPMC6029411 | biostudies-literature

Effect of 1α,25(OH)2 Vitamin D3 in Mutant P53 Glioblastoma Cells: Involvement of Neutral Sphingomyelinase1.

Project description:Glioblastoma is one the most aggressive primary brain tumors in adults, and, despite the fact that radiation and chemotherapy after surgical approaches have been the treatments increasing the survival rates, the prognosis of patients remains poor. Today, the attention is focused on highlighting complementary treatments that can be helpful in improving the classic therapeutic approaches. It is known that 1α,25(OH)2 vitamin D3, a molecule involved in bone metabolism, has many serendipidy effects in cells. It targets normal and cancer cells via genomic pathway by vitamin D3 receptor or via non-genomic pathways. To interrogate possible functions of 1α,25(OH)2 vitamin D3 in multiforme glioblastoma, we used three cell lines, wild-type p53 GL15 and mutant p53 U251 and LN18 cells. We demonstrated that 1α,25(OH)2 vitamin D3 acts via vitamin D receptor in GL15 cells and via neutral sphingomyelinase1, with an enrichment of ceramide pool, in U251 and LN18 cells. Changes in sphingomyelin/ceramide content were considered to be possibly responsible for the differentiating and antiproliferative effect of 1α,25(OH)2 vitamin D in U251 and LN18 cells, as shown, respectively, in vitro by immunofluorescence and in vivo by experiments of xenotransplantation in eggs. This is the first time 1α,25(OH)2 vitamin D3 is interrogated for the response of multiforme glioblastoma cells in dependence on the p53 mutation, and the results define neutral sphingomyelinase1 as a signaling effector.

| S-EPMC7694157 | biostudies-literature

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