Biology Reference
In-Depth Information
Chapter 16
Centrosomal Amplification and Related
Abnormalities Induced by Nucleoside
Analogs
Ofelia A. Olivero
Abstract Although very effective, anti-retroviral nucleoside analog drugs are
genotoxic in humans and carcinogenic in mice. The effect of the nucleoside
reverse transcriptase inhibitor (NRTI) AZT (zidovudine) as a centrosomal dis-
ruptor will be discussed. Centrosomal amplification was measured on MCF10A
cells by immunocytochemistry with antibodies to centrosomal proteins pericentrin
and Cep 170. Doses of 0, 10, 100, and 200 lM AZT for 24 h showed 0.9,1.75, 2.3,
and 3.1 % of cells containing centrosomal amplification (supernumerary centro-
somes), respectively. Furthermore, the origin of the extra centrosomes was ana-
lyzed by addressing the maturity of the structures. Typically mature centrosomes,
identified by the presence of Cep170 proteins, are the result of overduplication of
pre-existing centrosomes. Conversely, it is believed that, Cep170 negative,
immature centrosomes are the result of accumulation of the organelles by impaired
cytokinesis. Scoring of Cep170-stained AZT-induced centrosomes revealed that
40, 50, and 53 % of the supernumerary centrosomes in cells exposed to 10, 100,
and 200 lM AZT, respectively, were mature, compared to 22 % of unexposed
cells centrosomes in the control. Therefore, AZT-induced centrosomal amplifi-
cation is the result of both overduplication and cytokinesis impairment.
O. A. Olivero (
&
)
Laboratory of Cancer Biology and Genetics, Carcinogen-DNA Interactions Section 37
Convent Dr. MSC 4255, National Cancer Institute, NIH, Bldg 37 Rm 4032,
Bethesda, MD 20892-4255, USA
e-mail: oliveroo@exchange.nih.gov
