ABSTRACT
The t(11;22)(q24;q12) translocation is present in up to 95% of Ewing tumor patients and results in the formation of an EWS-FLI-1 fusion gene that encodes a chimeric transcription factor. Many alternative forms of EWS-FLI-1 exist because of variations in the location of the EWS and FLI-1 genomic breakpoints. Previous reports have shown that the type 1 fusion is associated with a significantly better prognosis than the other fusion types. It has been suggested that the observed clinical discrepancies result from different transactivation potentials of the various EWS-FLI-1 fusion proteins. In an attempt to identify genes whose expression levels are differentially modulated by structurally different EWS-FLI-1 transcription factors, we have used microarray technology to interrogate 19,000 sequence genes to compare gene expression profile of type 1 or non-type 1 Ewing sarcoma cell lines. Data analysis showed few qualitative differences on gene expression; expression of only 41 genes (0.215% of possible sequences analyzed) differed significantly between Ewing tumor cell lines carrying EWS-FLI-1 fusion type 1 with respect to those with non-type 1 fusion.
Subject(s)
Biomarkers, Tumor/genetics , Bone Neoplasms/genetics , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Neoplasm Proteins/genetics , Oncogene Proteins, Fusion/genetics , Proto-Oncogene Protein c-fli-1/genetics , Sarcoma, Ewing/genetics , Humans , Oligonucleotide Array Sequence Analysis , RNA, Messenger/metabolism , RNA-Binding Protein EWS , Reverse Transcriptase Polymerase Chain Reaction , Tumor Cells, CulturedABSTRACT
Chemotherapy with the alkylating agent BCNU (1,3-bis (2-chloroethyl)-1-nitrosourea) is the most commonly used chemotherapeutic agent for gliomas. However, the usefulness of this agent is limited because tumor cell resistance to BCNU is frequently found in clinical brain tumor therapy. The O6-methylguanine-DNA methyltransferase protein (MGMT) reverses alkylation at the O6 position of guanine and we have reported the role of MGMT in the response of brain tumors to alkylating agents. However, the different mechanisms underlying the patterns related to MGMT remain unclear. To better understand the molecular mechanism by which BCNU exerts its effect in glioma cell lines according MGMT expression, we used microarray technology to interrogate 3800 known genes and determine the gene expression profiles altered by BCNU treatment. Our results showed that treatment with BCNU alters the expression of a diverse group of genes in a time-dependent manner. A subset of gene changes was found common in both glioma cell lines and other subset is specific of each cell line. After 24 h of BCNU treatment, up-regulation of transcription factors involved in the nucleation of both RNA polymerase II and III transcription initiation complexes was reported. Interestingly, BCNU promoted the expression of actin-dependent regulators of chromatin. Similar effects were found with higher BCNU doses in MGMT+ cell line showing a similar mechanism that in MGMT-deficient cell with standard doses. Our data suggest that human glioma cell lines treated with BCNU, independently of MGMT expression, show changes in the expression of cell cycle and survival-related genes interfering the transcription mechanisms and the chromatin regulation.
Subject(s)
Antineoplastic Agents, Alkylating/pharmacology , Brain Neoplasms/genetics , Carmustine/pharmacology , Gene Expression/drug effects , Glioma/genetics , O(6)-Methylguanine-DNA Methyltransferase/biosynthesis , Cell Line, Tumor , Cell Proliferation/drug effects , Down-Regulation , Gene Expression Profiling , Humans , O(6)-Methylguanine-DNA Methyltransferase/drug effects , Oligonucleotide Array Sequence Analysis , RNA, Messenger/analysis , Reverse Transcriptase Polymerase Chain Reaction , Time Factors , Up-RegulationABSTRACT
The purpose of this study was to define gene expression profile changes in colorectal tumors in order to identify target genes involved in neoplastic progression. cDNA microarray analysis was used to detect differences in gene expression profiles between colon tumor samples obtained from 20 patients in different tumor stages. Genes included in the cDNA microarray were selected according to their role in the cell cycle, apoptosis process, drug resistance and transcription factor regulation. Cluster analysis showed 2 well differentiated gene expression profiles between colorectal tumors with or without lymph node involvement. Some of these genes are important regulators of apoptotic pathways (DAD1, APO3, DRAK1 or BIK), suggesting that this process could be associated with node involvement. Subsequent analysis of certain genes identified in the microarray analysis were confirmed by quantitative real-time PCR. Our data suggest that microarray technology could discriminate between the involvement of regional lymph node in colon cancer where apoptosis-related genes would be implied. This preliminary analysis also suggests that the gene expression profile may be useful in improving risk-group stratification.
