title: Modification of radiation-induced DNA double strand break repair pathways by chemicals extracted from Podophyllum hexandrum: an in vitro study in human blood leukocytes.
abstract: Radiation exposure is a serious threat to biomolecules, particularly DNA, proteins and lipids. Various exogenous substances have been reported to protect these biomolecules. In this study we explored the effect of pre-treatment with G-002M, a mixture of three active derivatives isolated from the rhizomes of Podophyllum hexandrum, on DNA damage response in irradiated human blood leukocytes. Blood was collected from healthy male volunteers, preincubated with G-002M and then irradiated with various doses of radiation. Samples were analyzed using flow cytometry to quantify DNA double strand break (DSB) biomarkers including γ-H2AX, P53BP1 and levels of ligase IV. Blood samples were irradiated in vitro and processed to determine time and dose-dependent kinetics. Semiquantitative RT-PCR was performed at various time points to measure gene expression of DNA-PKcs, Ku80, ATM, and 53BP1; each of these genes is involved in DNA repair signaling. Pre-treatment of blood with G-002M resulted in reduction of γ-H2AX and P53BP1 biomarkers levels and elevated ligase IV levels relative to non-G-002M-treated irradiated cells. These results confirm suppression in radiation-induced DNA DSBs. Samples pre-treated with G-002M and then irradiated also showed significant up-regulation of DNA-PKcs and Ku80 and downregulation of ATM and 53BP1 gene expressions, suggesting that G-002M plays a protective role against DNA damage. The protective effect of G-002M may be due to its ability to scavange radiation-induced free radicals or assist in DNA repair. Further studies are needed to decipher the role of G-002M on signaling molecules involved in radiation-induced DNA damage repair pathways.
authors: Radioprotective Drug Development Research Department, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, Timarpur, Delhi, 110054, India.
authors: Nitya N
authors: NN
authors: Srivastava
authors: Sandeep K
authors: SK
authors: Shukla
authors: M H
authors: MH
authors: Yashavarddhan
authors: Memita
authors: M
authors: Devi
authors: Rajendra P
authors: RP
authors: Tripathi
authors: Manju L
authors: ML
authors: Gupta
mesh_terms: D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism; D028141:Berberidaceae; D002478:Cells, Cultured; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects* / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects* / Q000235:genetics / Q000528:radiation effects; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D005720:Gamma Rays / Q000009:adverse effects*; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000072200:Ku Autoantigen; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D011035:Podophyllum / Q000737:chemistry*; D012333:RNA, Messenger / Q000235:genetics; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D004365:Drugs, Chinese Herbal; D005419:Flavonoids; C468783:H2AX protein, human; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D011837:Radiation-Protective Agents; C509544:Sinopodophyllum hexandrum extract; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen
keywords: DNA damage; P53BP1; Podophyllum hexandrum; non-homologous end joining; γ-H2AX