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Profiling of p53-responsive genes in human breast cancer cells harboring endogenous ts-p53 E285K

ABSTRACT: The ts-p53 E285K protein is a rare p53 mutant with temperature-sensitive (ts) loss of function characteristics. In cancer cells, which express ts-p53 E285K intrinsically, endogenous wild type p53 activity is reconstituted by appropriate cultivation temperature (permissive condition). At non-appropriate cultivation temperature (restrictive condition) this p53 mutant is inactive. The present study took advantage of this mechanism and employed IPH-926 lobular breast cancer cells and BT-474 ductal breast cancer cells, which both harbor endogenous ts-p53 E285K, for the transcriptional profiling of p53-responsive genes. This new approach eliminated the need for genetic modification or cytotoxic stimulation to achive a p53 response in the cells being investigated . Three subseqent passages of IPH-926 lobular breast cancer cells (harboring ts-p53 E285K) were seeded into two parallel culture dishes each and were allowed to adopt to restrictive and permissive condition for 24 h before analysis on Affymetrix U133 Plus 2.0 microarrays. Subsequently, this experiment was repeated with BT-474 ductal breast cancer cells (also harboring ts-p53 E285K). To gate out non-specific temperature effects, the same experiment was also performed with MCF-7 breast cancer cells (harboring wt p53). Probe sets differentially expressed at restrictive versus permissive condition in MCF-7 were considered as non-specifically regulated. These probe sets were excluded from the final statistical analysis of IPH-926 and BT-474 expression data. response to restored p53 activity

ORGANISM(S): Homo sapiens

SUBMITTER: Christgen M

PROVIDER: S-ECPF-GEOD-35006 | biostudies-other | 2012 Nov

REPOSITORIES: biostudies-other

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Profiling of p53-responsive genes in human breast cancer cells harboring endogenous ts-p53 E285K

2012-12-31 | GSE35006 | GEO

Profiling of p53-responsive genes in human breast cancer cells harboring endogenous ts-p53 E285K

Project description:The ts-p53 E285K protein is a rare p53 mutant with temperature-sensitive (ts) loss of function characteristics. In cancer cells, which express ts-p53 E285K intrinsically, endogenous wild type p53 activity is reconstituted by appropriate cultivation temperature (permissive condition). At non-appropriate cultivation temperature (restrictive condition) this p53 mutant is inactive. The present study took advantage of this mechanism and employed IPH-926 lobular breast cancer cells and BT-474 ductal breast cancer cells, which both harbor endogenous ts-p53 E285K, for the transcriptional profiling of p53-responsive genes. This new approach eliminated the need for genetic modification or cytotoxic stimulation to achive a p53 response in the cells being investigated . Three subseqent passages of IPH-926 lobular breast cancer cells (harboring ts-p53 E285K) were seeded into two parallel culture dishes each and were allowed to adopt to restrictive and permissive condition for 24 h before analysis on Affymetrix U133 Plus 2.0 microarrays. Subsequently, this experiment was repeated with BT-474 ductal breast cancer cells (also harboring ts-p53 E285K). To gate out non-specific temperature effects, the same experiment was also performed with MCF-7 breast cancer cells (harboring wt p53). Probe sets differentially expressed at restrictive versus permissive condition in MCF-7 were considered as non-specifically regulated. These probe sets were excluded from the final statistical analysis of IPH-926 and BT-474 expression data. response to restored p53 activity

2012-12-31 | E-GEOD-35006 | biostudies-arrayexpress

Transcriptome profiling identifies genes and pathways deregulated upon floxuridine treatment in colorectal cancer cells harboring GOF mutant p53.

Project description:Mutation in TP53 is a common genetic alteration in human cancers. Certain tumor associated p53 missense mutants acquire gain-of-function (GOF) properties and confer oncogenic phenotypes including enhanced chemoresistance. The colorectal cancers (CRC) harboring mutant p53 are generally aggressive in nature and difficult to treat. To identify a potential gene expression signature of GOF mutant p53-driven acquired chemoresistance in CRC, we performed transcriptome profiling of floxuridine (FUdR) treated SW480 cells expressing mutant p53(R273H) (GEO#: GSE77533). We obtained several genes differentially regulated between FUdR treated and untreated cells. Further, functional characterization and pathway analysis revealed significant enrichment of crucial biological processes and pathways upon FUdR treatment in SW480 cells. Our data suggest that in response to chemotherapeutics treatment, cancer cells with GOF mutant p53 can modulate key cellular pathways to withstand the cytotoxic effect of the drugs. The genes and pathways identified in the present study can be further validated and targeted for better chemotherapy response in colorectal cancer patients harboring mutant p53.

| S-EPMC4832042 | biostudies-literature

Transcription profiling of human breast cancer cell lines to investigate p53 status in breast cancer

Project description:Breast cancer subtypes identified in genomic studies have different underlying genetic defects. Mutations in the tumor suppressor p53 occur more frequently in estrogen receptor (ER) negative, basal-like and HER2-amplified tumors than in luminal, ER positive tumors. Thus, because p53 mutation status is tightly linked to other characteristics of prognostic importance, it is difficult to identify p53's independent prognostic effects. The relation between p53 status and subtype can be better studied by combining data from primary tumors with data from isogenic cell line pairs (with and without p53 function). In this study, the p53-dependent gene expression signatures of four cell lines (MCF-7, ZR-75-1, and two immortalized human mammary epithelial cell lines) were identified by comparing p53-RNAi transduced cell lines to their parent cell lines. Cell lines were treated with vehicle only or doxorubicin to identify p53 responses in both non-induced and induced states. Each cell line displayed unique patterns of gene expression, but cell type specific trends were evident. A common gene expression signature associated with p53 loss across all four cell lines was identified. This signature showed overlap with the signature of p53 loss in primary breast tumors and predicted relapse-free survival and overall survival in independent test data sets. Experiment Overall Design: We analyzed 48 arrays performed using 48 polyA RNA samples. RNAs were collected from cell lines treated with an IC50 dose of doxorubicin hydrochloride or with a feeding control. Each cell line had its own reference which represented the second sample on the dual channel array. These untreated RNAs were prepared by pooling four harvests of that cell line at 60-80% confluence and 48h after feeding

| S-ECPF-GEOD-3178 | biostudies-other

Transcription profiling time series of human estrogen-responsive human breast cancer cells treated with 17 beta-estradiol

Project description:Human estrogen-responsive breast cancer cell line ZR-75-1 was treated with 10nM of 17 beta-estradiol. Gene expression was analyzed on total RNA extracted before or after 1, 2, 4, 6, 8, 12, 16, 20, 24, 28 and 32 hours hormonal stimulation. For each condition 2 technical replicates were performed, except the reference sample (before stimulation - 0h) which was in quadruplicate and the 4h sample in triplicate.

| S-ECPF-TABM-631 | biostudies-other

Expression of human endogenous retrovirus env genes in the blood of breast cancer patients.

Project description:Human endogenous retroviruses (HERV) env proteins have been recently reported to be significantly up-regulated in certain cancers. Specifically, mRNA and protein levels of HERV-K (HML-2) are up-regulated in the blood plasma or serum of breast cancer patients. Here, we collected blood samples of 49 breast cancer patients and analyzed mRNA expressions of various HERVs env genes including HERV-R, HERV-H, HERV-K, and HERV-P by real-time PCR. The expression of env genes were significantly increased in the blood of primary breast cancer patients but were decreased in patients undergoing chemotherapy to a similar level with benign patients. When we compared the group currently undergoing chemotherapy and those patients undergoing chemotherapy simultaneously with radiotherapy, HERVs env genes were reduced more in the chemotherapy only group, suggesting that chemotherapy is more effective in reducing HERV env gene expression than is radiotherapy. Among chemotherapy groups, HERV env gene expression was the lowest in the taxotere- or taxol-treated group, suggesting that taxotere and taxol can reduce HERVs env expression. These data suggest the potential to use HERVs env genes as a diagnosis marker for primary breast cancer, and further studies are needed to identify the mechanism and physiological significance of the reduction of HERV env gene expression during chemotherapy.

| S-EPMC4100088 | biostudies-literature

Transcription profiling of human breast cancer samples to generate an expression signature for p53 status

Project description:The biological tumor samples (ie, breast tumor specimens) consisted of freshly frozen breast tumors from a population-based cohort of 315 women representing 65% of all breast cancers resected in Uppsala County, Sweden, from January 1, 1987 to December 31, 1989. Estrogen receptor status was determined by biochemical assay as part of the routine clinical procedure. An experienced pathologist determined the Elston-Ellis grades of the tumors, classifying the tumors into low, medium and high-grade tumors. The clinico-pathological characteristics accompanying each tumor include p53 status, ER status, tumor grade, lymph node status and patient age. Experiment Overall Design: All tumor specimens were assessed on U133 A and B arrays.

| S-ECPF-GEOD-3494 | biostudies-other

Identification of suitable endogenous control genes for microRNA gene expression analysis in human breast cancer.

Project description:The discovery of microRNAs (miRNAs) added an extra level of intricacy to the already complex system regulating gene expression. These single-stranded RNA molecules, 18-25 nucleotides in length, negatively regulate gene expression through translational inhibition or mRNA cleavage. The discovery that aberrant expression of specific miRNAs contributes to human disease has fueled much interest in profiling the expression of these molecules. Real-time quantitative PCR (RQ-PCR) is a sensitive and reproducible gene expression quantitation technique which is now being used to profile miRNA expression in cells and tissues. To correct for systematic variables such as amount of starting template, RNA quality and enzymatic efficiencies, RQ-PCR data is commonly normalised to an endogenous control (EC) gene, which ideally, is stably-expressed across the test sample set. A universal endogenous control suitable for every tissue type, treatment and disease stage has not been identified and is unlikely to exist, so, to avoid introducing further error in the quantification of expression data it is necessary that candidate ECs be validated in the samples of interest. While ECs have been validated for quantification of mRNA expression in various experimental settings, to date there is no report of the validation of miRNA ECs for expression profiling in breast tissue. In this study, the expression of five miRNA genes (let-7a, miR-10b, miR-16, miR-21 and miR-26b) and three small nucleolar RNA genes (RNU19, RNU48 and Z30) was examined across malignant, benign and normal breast tissues to determine the most appropriate normalisation strategy. This is the first study to identify reliable ECs for analysis of miRNA by RQ-PCR in human breast tissue.

| S-EPMC2533012 | biostudies-literature

p53 responsive elements in human retrotransposons.

Project description:Long interspersed nuclear elements-1 (L1s) are highly repetitive DNA elements that are capable of altering the human genome through retrotransposition. To protect against L1 retroposition, the cell downregulates the expression of L1 proteins by various mechanisms, including high-density cytosine methylation of L1 promoters and DICER-dependent destruction of L1 mRNAs. In this report, a large number of p53 responsive elements, or p53 DNA binding sites, were detected in L1 elements within the human genome. At least some of these p53 responsive elements are functional and can act to increase the levels of L1 mRNA expression. The p53 protein can directly bind to a short 15-nucleotide sequence within the L1 promoter. This p53 responsive element within L1 is a recent addition to evolution, appearing approximately 20 million years ago. This suggests an interplay between L1 elements, which have a rich history of causing changes in the genome, and the p53 protein, the function of which is to protect against genomic changes. To understand these observations, a model is proposed in which the increased expression of L1 mRNAs by p53 actually increases, rather than decreases, the genomic stability through amplification of p53-dependent processes for genomic protection.

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2006-02-25 | GSE4292 | GEO

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