Cleavage of cellular DNA by calicheamicin γ1

• It is assumed that the efficient antitumor activity of calicheamicin γ1 is mediated by its ability to introduce DNA double-strand breaks in cellular DNA. To test this assumption we have compared calicheamicin γ1-mediated cleavage of cellular DNA and purified plasmid DNA. Cleavage of purified plasmid DNA was not inhibited by excess tRNA or protein indicating that calicheamicin γ1 specifically targets DNA. Cleavage of plasmid DNA was not affected by incubation temperature. In contrast, cleavage of cellular DNA was 45-fold less efficient at 0°C as compared to 37° due to poor cell permeability at low temperatures. The ratio of DNA double-strand breaks (DSB) to single-stranded breaks (SSB) in cellular DNA was 1:3, close to the 1:2 ratio observed when calicheamicin γ1 cleaved purified plasmid DNA. DNA strand breaks introduced by calicheamicin γ1 were evenly distributed in the cell population as measured by the comet assay. Calicheamicin γ1-induced DSBs were repaired slowly but completely and resulted in high levels of H2AX phosphorylation and efficient cell cycle arrest. In addition, the DSB-repair deficient cell line Mo59J was hyper sensitive to calicheamicin γ. The data indicate that DSBs is the crucial damage after calicheamicin γ1 and that calicheamicin γ1-induced DSBs are recognized normally. The high DSB:SSB ratio, specificity for DNA and the even damage distribution makes calicheamicin γ1 a superior drug for studies of the DSB-response and emphasizes its usefulness in treatment of malignant disease.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Farmakologi och toxikologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Pharmacology and Toxicology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Keyword

Bleomycin

Calicheamicin γ1

DNA damage

DNA double-strand break

DNA repair

DNA single-strand break

Ionizing radiation

calicheamicin gamma1

cell DNA

double stranded DNA

histone H2A

plasmid DNA

single stranded DNA

transfer RNA

article

cell membrane permeability

cell population

comet assay

comparative study

controlled study

DNA cleavage

DNA purification

DNA strand breakage

gene targeting

human

human cell

low temperature

mitosis inhibition

priority journal

protein phosphorylation

temperature dependence

Aminoglycosides

Anti-Bacterial Agents

DNA

Enediynes

Fibroblasts

Humans

Aminoglycosides

Anti-Bacterial Agents

pharmacology

DNA

drug effects

metabolism

DNA Damage

Enediynes

Fibroblasts

Humans

Publication and Content Type

ref (subject category)

art (subject category)