title: HeLa Cells Containing a Truncated Form of DNA Polymerase Beta are More Sensitized to Alkylating Agents than to Agents Inducing Oxidative Stress.
abstract: The present study was aimed at determining the effects of alkylating and oxidative stress inducing agents on a newly identified variant of DNA polymerase beta (polβ Δ208-304) specific for ovarian cancer. Pol β Δ208-304 has a deletion of exons 11-13 which lie in the catalytic part of enzyme. We compared the effect of these chemicals on HeLa cells and HeLa cells stably transfected with this variant cloned into in pcDNAI/neo vector by MTT, colony forming and apoptosis assays. Polβ Δ208-304 cells exhibited greater sensitivity to an alkylating agent and less sensitivity towards H2O2 and UV when compared with HeLa cells alone. It has been shown that cell death in Pol β Δ208-304 transfected HeLa cells is mediated by the caspase 9 cascade. Exon 11 has nucleotidyl selection activity, while exons 12 and 13 have dNTP selection activity. Hence deletion of this part may affect polymerizing activity although single strand binding and double strand binding activity may remain same. The lack of this part may adversely affect catalytic activity of DNA polymerase beta so that the variant may act as a dominant negative mutant. This would represent clinical significance if translated into a clinical setting because resistance to radiation or chemotherapy during the relapse of the disease could be potentially overcome by this approach.
authors.affiliation: Department of Biotechnology, Panskura Banamali College; Panskura RS, Purba Medinipur, West Bengal, India E-mail : bhattacharyya_nandan@rediffmail.com.
authors.forename: Kalyani
authors.initials: K
authors.lastname: Khanra
authors.forename: Anindita
authors.initials: A
authors.lastname: Chakraborty
authors.forename: Nandan
authors.initials: N
authors.lastname: Bhattacharyya
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D019951:DNA Polymerase beta / Q000235:genetics / Q000378:metabolism*; D005091:Exons / Q000235:genetics*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
chemical_list: D000477:Alkylating Agents; D016877:Oxidants; D012333:RNA, Messenger; D006861:Hydrogen Peroxide; D019951:DNA Polymerase beta; D020169:Caspases