title: Cytotoxic and radio-sensitizing effects of polyphenolic acetates in a human glioma cell line (BMG-1).
abstract: OBJECTIVE
  Polyphenolic acetates (PAs) have antioxidant/ pro-oxidant properties and can also acetylate proteins (enzymes) by a novel acetoxy drug: calreticulin transacetylase acetylation system. While PAs have been investigated as pharmacological agents for the treatment of various diseases, their potential as anti-cancer agents or their efficacy as an adjuvant in anti-cancer therapeutics remains to be explored. In the present study we investigated the cytotoxic and radio-sensitizing effects of 7, 8- diacetoxy-4-methyl coumarin (DAMC) and 7- acetoxy-4-methyl coumarin (7-AMC) in a human glioma cell line (BMG-1).
  
  
  METHODS
  Cytotoxic and radio-sensitizing effects were investigated by studying reactive oxygen species (ROS) levels, metabolic viability, clonogenic survival, growth inhibition, cell cycle perturbation, DNA repair and cytogenetic damage, besides analyzing the histone (H3) acetylation.
  
  
  RESULTS
  Exposure of cells to DAMC and 7-AMC for 24 h showed a dose dependent increase in toxicity as indicated by reduced metabolic viability, clonogenic survival and cell proliferation, with DAMC being more toxic than 7-AMC. The degree of radiosensitization by DAMC was also higher as compared to 7-AMC as reflected by a decrease in the clonogenicity, enhanced radiation-induced cell cycle perturbation and apoptosis. DAMC impaired the removal of radiation-induced DNA double stranded breaks (measured by γH2AX immuno- fluorescence) and enhanced the cytogenetic damage (micronuclei formation), leading to an increase in mitotic death. While DAMC alone induced pan nuclear γH2AX fluorescence, both pan nuclear and spatially restricted foci was observed with the combined treatment (DAMC + Radiation) suggesting a complex nature of DNA damage and repair. DAMC- induced cytotoxic and radio-sensitizing effects were independent of its pro-oxidant activity, whereas histone H3 lysine (9/14) hyperacetylation appeared to be a potential target, regulating cellular responses to ionizing radiation (IR).
  
  
  CONCLUSIONS
  The polyphenolic acetate 7, 8- diacetoxy-4-methyl coumarin (DAMC) demonstrates both anticancer effects and radiosensitizing potential under in vitro conditions.
authors.forename: Amit
authors.initials: A
authors.lastname: Verma
authors.forename: Kavya
authors.initials: K
authors.lastname: Venkateswaran
authors.forename: Abdullah
authors.initials: A
authors.lastname: Farooque
authors.forename: Anant Narayan
authors.initials: AN
authors.lastname: Bhatt
authors.forename: Namita
authors.initials: N
authors.lastname: Kalra
authors.forename: Anu
authors.initials: A
authors.lastname: Arya
authors.forename: Ashish
authors.initials: A
authors.lastname: Dhawan
authors.forename: Mohan B
authors.initials: MB
authors.lastname: Arya
authors.forename: Hanumantharao G
authors.initials: HG
authors.lastname: Raj
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Prasad
authors.forename: Virinder S
authors.initials: VS
authors.lastname: Parmar
authors.affiliation: Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Majumdar Marg, Timarpur. Delhi-110 054, India. bsd@inmas.drdo.in.
authors.forename: Bilikere S
authors.initials: BS
authors.lastname: Dwarakanath
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000107:Acetylation / Q000187:drug effects; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003374:Coumarins / Q000494:pharmacology*; D004249:DNA Damage / Q000187:drug effects; D004260:DNA Repair / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D059808:Polyphenols / Q000494:pharmacology; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D014468:Umbelliferones / Q000494:pharmacology*
chemical_list: C114369:7,8-diacetoxy-4-methylcoumarin; D000085:Acetates; D000970:Antineoplastic Agents; D003374:Coumarins; D059808:Polyphenols; D011838:Radiation-Sensitizing Agents; D014468:Umbelliferones; C032078:4-methylumbelliferyl acetate