Project description:Genomic instability is one of the hallmarks of cancer. Several chemotherapeutic drugs and radiotherapy induce DNA damage to prevent cancer cell replication. Cells in turn activate different DNA damage response (DDR) pathways to either repair the damage or induce cell death. These DDR pathways also elicit metabolic alterations which can play a significant role in the proper functioning of the cells. The understanding of these metabolic effects resulting from different types of DNA damage and repair mechanisms is currently lacking. In this study, we used NMR metabolomics to identify metabolic pathways which are altered in response to different DNA damaging agents. By comparing the metabolic responses in MCF-7 cells, we identified the activation of poly (ADP-ribose) polymerase (PARP) in methyl methanesulfonate (MMS)-induced DNA damage. PARP activation led to a significant depletion of NAD+. PARP inhibition using veliparib (ABT-888) was able to successfully restore the NAD+ levels in MMS-treated cells. In addition, double strand break induction by MMS and veliparib exhibited similar metabolic responses as zeocin, suggesting an application of metabolomics to classify the types of DNA damage responses. This prediction was validated by studying the metabolic responses elicited by radiation. Our findings indicate that cancer cell metabolic responses depend on the type of DNA damage responses and can also be used to classify the type of DNA damage.
Project description:Targetted metabolomics in U2OS PRDX1 WT and PRDX1-/- While cellular metabolism impacts the DNA damage response, a systematic understanding of the metabolic requirements that are crucial for DNA damage repair has yet to be achieved. Here, we investigate the metabolic enzymes and processes that are essential when cells are exposed to DNA damage. By integrating functional genomics with chromatin proteomics and metabolomics, we provide a detailed description of the interplay between cellular metabolism and the DNA damage response. Subsequent analysis identified Peroxiredoxin 1, PRDX1, as fundamental for DNA damage repair. During the DNA damage response, PRDX1 translocates to the nucleus where it is required to reduce DNA damage-induced nuclear reactive oxygen species levels. Moreover, PRDX1 controls aspartate availability, which is required for the DNA damage repair-induced upregulation of de novo nucleotide synthesis. Loss of PRDX1 leads to an impairment in the clearance of γΗ2ΑΧ nuclear foci, accumulation of replicative stress and cell proliferation defects, thus revealing a crucial role for PRDX1 as a DNA damage surveillance factor.
Project description:Genotoxic damage is known to disrupt cellular functions and is lethal if not repaired properly. We compare the transcriptional programs activated in response to genotoxic DNA damage induced by ionizing radiation (IR) in pre-B cells from mice deficient in various DNA damage response (DDR) genes. We used microarrays to detail the global gene expression of mutated cells compared to WT cells, with and without exposure to the DNA damaging agent ionizing radiation (IR), and identified differentially-regulated genes and associated pathways responding to the damage.
Project description:Cellular senescence is defined as permanent growth arrest induced by various stresses. Although the transcriptional activity of p53 is essential for senescence induction, the downstream genes that are crucial for senescence remain unsolved. We developed an experimental system in which either senescence or apoptosis is specifically induced in the same cell line (hepatocarcinoma HepG2 cells having the intact p53 gene) by altering concentrations of a DNA-damaging drug and compared gene expression profiles by using microarray analysis to distinguish genes specific for senescence from those universally respond to DNA damage. When we compared the expression profiles at low versus high doses of etoposide, 20 genes were found to be differentially upregulated by more than 2-fold at a low dose of etoposide, which are expected to function in senescence induction. Microarray results were further confirmed by qPCR.
Project description:Transcriptional profiling of human fibroblast cells after DNA damage with Camptothecin or Etoposide or Neocarzinostatin Upon DNA damage, the DNA damage response (DDR) elicits a complex signaling cascade, which includes the induction of multiple non-coding RNA species. Recently long non-coding RNAs (lncRNAs) have been shown to contribute to DDR by regulating gene expression. However, very little is known about the role that lncRNAs play in regulating DNA Repair. Using a genome-wide microarray screen we identified a novel ubiquitously expressed lncRNA, DDSR1 (DNA damage-sensitive RNA 1), which is induced upon DNA damage by several DNA double-strand break (DSB) agents. Two-condition experiment, Control vs. DNA damage human fibroblast cells. No Replicates, DNA damage was induced with either Camptothecin or Etoposide or Neocarzinostatin, Total RNA or Nuclear RNA was profiled.
Project description:The major histocompatibility complex class II (MHC II) is important for the adaptive immune response because it presents processed antigens to CD4-positive T-cells. Conventional chemotherapeutic agents (e.g., melphalan, adriamycin, hydroxyurea) induce tumor cell death by causing DNA double strand breaks (DSBs), which are crucial for anti-tumor effects. However, the cellular response induced at low doses of these agents that do not cause immediate cell death is unclear. We have employed microarray expression profiling to identify genes which are induced by low dose of chemotherapeutic agents. Multiple myeloma cell line KMS12PE was treated with vehicle, 2 μM melphalan, or 50 nM adriamycin. These agents transcriptionally induced the major histocompatibility complex class II (MHC II) genes. They also increased the expressions of MHC class II transactivator (CIITA), the master regulator of MHC II genes and interferon regulatory factor 1 (IRF1), a transcription factor for CIITA.