Genome position and gene amplification - expressional profiling of methotrexate resistant colonies
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE6361 | GEO | 2007/10/08
SECONDARY ACCESSION(S): PRJNA99573
REPOSITORIES: GEO
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Project description:We investigated the influence of genome position on propensity to amplify. First, we integrated a mutant form of DHFR into different positions in the human genome, challenged cells with methotrexate and then studied the genomic alterations arising in drug resistant cells. We observed site specific differences in methotrexate sensitivity, organization of amplicons and amplification frequency. One site was uniquely associated with a significantly enhanced propensity to amplify and recurrent amplicon boundaries, possibly implicating a rare folate sensitive fragile site in initiating amplification. Hierarchical clustering of gene expression patterns and subsequent gene enrichment analysis revealed two clusters differing significantly in expression of MYC target genes independent of integration site. We introduced a mutant form of DHFR (L22F), which confers greater resistance to methotrexate than the wild type (endogenous) gene into HCT116+chr3 cells and isolated independent clones containing DHFR* at different positions in the genome and identified genome sequences flanking the integration site of DHFR* using inverse PCR. For further analysis, we selected only clones, which were considered to have a single insertion of DHFR* by inverse PCR (13 independent insertion sites). The individual insertion site clones were further characterized with respect to genome copy number profiles. To select methotrexate resistant colonies, we exposed cells to a concentration of methotrexate that was three to four times the IC-50 for each integration site. Genomic copy number profiles were obtained for isolated resistant colonies (GSE6262) by using UCSF HumArray platform (GPL4421). Twelve methotrexate resistant colonies (four different integration sites) were selected for microarray analysis of gene expression at the mRNA level. The untreated integration site clone was used as the reference (Cy5 labeled cDNA) for each of the hybridizations with its respective resistant colonies (Cy3 labeled cDNA). Hybridizations were carried out on arrays of printed long oligonucleotides (70mers) containing 21,000 elements (Operon V2.0, printed in J. David Gladstone Institutes, Genomics Core Laboratory).
2007-10-08 | E-GEOD-6361 | biostudies-arrayexpress
Project description:We investigated the influence of genome position on propensity to amplify. First, we integrated a mutant form of DHFR into different positions in the human genome, challenged cells with methotrexate and then studied the genomic alterations arising in drug resistant cells. We observed site specific differences in methotrexate sensitivity, organization of amplicons and amplification frequency. One site was uniquely associated with a significantly enhanced propensity to amplify and recurrent amplicon boundaries, possibly implicating a rare folate sensitive fragile site in initiating amplification. Hierarchical clustering of gene expression patterns and subsequent gene enrichment analysis revealed two clusters differing significantly in expression of MYC target genes independent of integration site. Keywords: Gene amplification, array CGH, chromosomal fragile sites
2007-10-08 | GSE6360 | GEO
Project description:Amplifications, regions of focal high level copy number change, lead to overexpression of oncogenes or drug resistance genes in tumors. Their presence is often associated with poor prognosis; however the use of amplification as a mechanism for overexpression of a particular gene in tumors varies. To investigate the influence of genome position on propensity to amplify, we integrated a mutant form of DHFR into different positions in the human genome, challenged cells with methotrexate and then studied the genomic alterations arising in drug resistant cells. We observed site specific differences in methotrexate sensitivity, organization of amplicons and amplification frequency. One site was uniquely associated with a significantly enhanced propensity to amplify and recurrent amplicon boundaries, possibly implicating a rare folate sensitive fragile site in initiating amplification. Hierarchical clustering of gene expression patterns and subsequent gene enrichment analysis revealed two clusters differing significantly in expression of MYC target genes independent of integration site. These studies suggest that genome context together with the particular challenges to genome stability experienced during the progression to cancer contribute to the propensity to amplify a specific oncogene or drug resistance gene, whereas the overall functional response to drug (or other) challenge may be independent of the genomic location of an oncogene. Keywords: Gene amplification, array CGH, chromosomal fragile sites
2007-10-08 | GSE6262 | GEO
Project description:A summary of the work associated to these microarrays is the following: Methotrexate (MTX) is one of the earliest cytotoxic drugs used in cancer therapy, and despite the isolation of multiple other folate antagonists, methotrexate maintains its significant role as a treatment for different types of cancer and other disorders. The usefulness of treatment with methotrexate is limited by the development of drug resistance, which may be acquired through different ways. To get insights into the mechanisms associated with drug resistance and sensitization we have performed a functional analysis of genes deregulated in methotrexate resistant cells, either due to its co-amplification with the DHFR gene or as a result of a transcriptome screening using microarrays. Genes adjacent to dhfr locus and included in the 5q14 amplicon were overexpressed in HT29 MTX-resistant cells. Treatment with siRNAs against those genes caused a slight reduction in cell viability in both HT29 sensitive and resistant cells. On the other hand, microarray analysis of HT29 and HT29 MTX resistant cells unveiled overexpression of caveolin 1, enolase 2 and PKCa genes in treated cells without concomitant copy number gain. siRNAs against these three genes effectively reduced cell viability and caused a decreased MTX resistance capacity. Moreover, overexpression of E-cadherin, which was found underexpressed in MTX-resistant cells, also sensitized the cells toward the chemotherapeutic agent. We provide functional evidences indicating that caveolin 1 and E-cadherin may play a critical role in cell survival and may constitute potential targets for coadjuvant therapy. Keywords: DHFR, Methotrexate, drug resistance
2008-09-08 | GSE11440 | GEO
Project description:A summary of the work associated to these microarrays is the following:; Methotrexate (MTX) is one of the earliest cytotoxic drugs used in cancer therapy, and despite the isolation of multiple other folate antagonists, methotrexate maintains its significant role as a treatment for different types of cancer and other disorders. The usefulness of treatment with methotrexate is limited by the development of drug resistance, which may be acquired through different ways. To get insights into the mechanisms associated with drug resistance and sensitization we have performed a functional analysis of genes deregulated in methotrexate resistant cells, either due to its co-amplification with the DHFR gene or as a result of a transcriptome screening using microarrays. Genes adjacent to dhfr locus and included in the 5q14 amplicon were overexpressed in HT29 MTX-resistant cells. Treatment with siRNAs against those genes caused a slight reduction in cell viability in both HT29 sensitive and resistant cells. On the other hand, microarray analysis of HT29 and HT29 MTX resistant cells unveiled overexpression of caveolin 1, enolase 2 and PKCa genes in treated cells without concomitant copy number gain. siRNAs against these three genes effectively reduced cell viability and caused a decreased MTX resistance capacity. Moreover, overexpression of E-cadherin, which was found underexpressed in MTX-resistant cells, also sensitized the cells toward the chemotherapeutic agent. We provide functional evidences indicating that caveolin 1 and E-cadherin may play a critical role in cell survival and may constitute potential targets for coadjuvant therapy. Experiment Overall Design: Two cell lines are compared in the study, which are HT29 colon cancer cells sensitive to methotrexate and HT29 cells resistant to 10e-5M MTX. Six samples are provided which correspond to triplicated of each cell line. The samples provided were subsequently normalyzed and analyzed using the specific software GeneSpring GX v7.3.1.
2008-10-25 | E-GEOD-11440 | biostudies-arrayexpress
Project description:The abstract of the associated publication (Selga E, Noé V, Ciudad CJ. Biochemical Pharmacology, 2008) is the following: While studying differentially expressed genes between sensitive and 10-5 M Methotrexate (MTX) resistant HT29 human colon cancer cells, we identified some members of the aldo-keto reductase (AKR) superfamily. The study was followed with the member AKR1C1 (EC 1.1.1.213), validating its increase in mRNA and protein levels in MTX resistant cells. The genomic content for AKR1C1 remained unchanged between sensitive and resistant cells, thereby excluding a mechanism of AKR1C1 gene amplification. Thus, we cloned the AKR1C1 human promoter and performed luciferase experiments that revealed a transcriptional regulation of the gene in the resistant cells. Computational studies showed a putative binding site for the transcription factor Sp1. The co-transfection of Sp1 or Sp3 with different constructs of AKR1C1 promoter deletions, including and excluding the proximal GC-box, demonstrated a key role for these factors in regulating AKR1C1 transcriptional activity. Gel-shift assays revealed an increase in Sp1 and Sp3 binding in resistant compared to sensitive cells, without differences in Sp1 protein levels. Dephosphorylation of the extracts coincided with a decrease in Sp1 binding, which is consistent with a process of regulation of Sp1 by phosphorylation. We also investigated the possible relationship between AKR1C1 expression and MTX action. Overexpression of AKR1C1 counteracted the S-phase accumulation of cells and apoptosis caused by MTX treatment. This suggests a role of AKR1C1 in cell proliferation. Finally, overexpression of AKR1C1 in MTX sensitive HT29 cells conferred resistance to the chemotherapeutic agent and silencing of AKR1C1 by means of iRNA technology sensitized the cells to MTX. Keywords: DHFR, Methotrexate, drug-resistance
2007-12-30 | GSE9412 | GEO
Project description:bulk sequencing outputs of Caco2 cells after exposure to permeability modifying and permeability rescuing agents. To identify the molecular drivers for methotrexate-induced barrier dysfunction, we conducted RNA sequencing on Caco2 spheroids treated with methotrexate and lactoferrin. Given our observation that barrier function was compromised as early as 4-6 hours after exposure to methotrexate, we isolated RNA from spheroids 4-hour post-treatment to capture the transcriptional events responsible for initiating the processes.
2020-01-10 | GSE140066 | GEO
Project description:Drug repurposing is a fast and effective way to develop drugs for an emerging disease such as COVID-19. The main challenges of effective drug repurposing are the discoveries of the right therapeutic targets and the right drugs for combating the disease. Here, we present a systematic repurposing approach, combining Homopharma and hierarchal systems biology networks (HiSBiN), to predict 327 therapeutic targets and 21,233 drug-target interactions of 1,592 FDA drugs for COVID-19. Among these multi-target drugs, eight candidates (along with pimozide and valsartan) were tested and methotrexate was identified to affect 14 therapeutic targets suppressing SARS-CoV-2 entry, viral replication, and COVID-19 pathologies. Through the use of in vitro (EC50 = 0.4 uM) and in vivo models, we show that methotrexate is able to inhibit COVID-19 via multiple mechanisms. Our in vitro studies illustrate that methotrexate can suppress SARS-CoV-2 entry and replication by targeting furin and DHFR of the host, respectively. Additionally, methotrexate inhibits all four SARS-CoV-2 variants of concern. In a Syrian hamster model for COVID-19, methotrexate reduced virus replication, inflammation in the infected lungs. By analysis of transcriptomic analysis of collected samples from hamster lung, we uncovered that neutrophil infiltration and the pathways of innate immune response, adaptive immune response and thrombosis are modulated in the treated animals. We demonstrate that this systematic repurposing approach is potentially useful to identify pharmaceutical targets, multi-target drugs and regulated pathways for a complex disease. Our findings indicate that methotrexate is established as a promising drug against SARS-CoV-2 variants and can be used to treat lung damage and inflammation in COVID-19, warranting future evaluation in clinical trials.
2022-12-13 | GSE179709 | GEO
Project description:Caco2 response to methotrexate, lactoferrin, and methotrexate-lactoferrin co-exposure
| PRJNA588171 | ENA