Increased expression of DNA-dependent protein kinase confers resistance to adriamycin.
Acquired resistance to adriamycin (ADR) in an HL60 cell line is shown to be accompanied by an increase in DNA-dependent protein kinase catalytic subunit (DNA-PKcs) at both the protein and mRNA levels (15-20-fold) and an overall 3-fold increase in DNA-PK enzyme activity. The other components of the DNA-PK Ku autoantigen complex, Ku70 and Ku80, were 3-fold increased and unchanged, respectively. Time dependent repair of ADR-induced DNA damage was measured by the neutral comet assay and found to be more efficient in the drug resistant cell line (HL60/ADR). Antisense RNA transfection reduced the protein expression of DNA-PKcs to 50% in HL60/ADR and partially reversed drug resistance. A fibroblast cell line from a severe combined immunodeficient (SCID) mouse was deficient in functional DNA-PKcs and showed increased sensitivity to ADR and other DNA damaging agents compared to wild type. These studies demonstrate that alteration in DNA-PK can contribute to chronic stress response leading to acquired drug resistance. The overexpression of DNA-PK is thus shown to be a novel cellular adaptation mechanistically contributing to the resistance of cancer cells to the anthracycline drug adriamycin, and as such, may have implications for its therapeutic use.
Department of Pharmacology, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, PA 19111, USA.
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D000222:Adaptation, Physiological; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D034961:Antigens, Nuclear; D001483:Base Sequence; D002460:Cell Line; D004249:DNA Damage; D004265:DNA Helicases; D017931:DNA Primers / Q000235:genetics; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics / Q000502:physiology; D015870:Gene Expression; D018922:HL-60 Cells; D006801:Humans; D000072200:Ku Autoantigen; D051379:Mice; D016513:Mice, SCID; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016372:RNA, Antisense / Q000235:genetics; D014162:Transfection
D000903:Antibiotics, Antineoplastic; D034961:Antigens, Nuclear; D017931:DNA Primers; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016372:RNA, Antisense; D004317:Doxorubicin; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen