In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 98, No. 20 ( 2001-09-25), p. 11283-11288
Abstract:
Cancer cells and aneuploid cell lines can acquire resistance
against multiple unrelated chemotherapeutic drugs that are over 3,000-fold those of normal levels and display spontaneous resistances
up to 20-fold of normal levels. Two different mechanisms were proposed for this phenotype: ( i ) classical mutation of drug
metabolizing genes or ( ii ) chromosome reassortments,
catalyzed by cancer- and cell line-specific aneuploidy, which generate, via new gene dosage combinations, a plethora of cancer phenotypes,
including drug resistance. To distinguish between these mechanisms, we have asked whether three mouse cell lines can become drug resistant,
from which two or three genes have been deleted, and on which multidrug resistance is thought to depend: Mdr1a , Mdr1b , and Mrp1 . Because all three lines
could acquire multidrug resistance and were aneuploid, whereas diploid mouse cells could not, we conclude that aneuploid cells become drug
resistant via specific chromosome assortments, independent of putative resistance genes. We have asked further whether aneuploid
drug-resistant Chinese hamster cells revert spontaneously to drug sensitivity in the absence of cytotoxic drugs at the high rates that
are typical of chromosome reassortments catalyzed by aneuploidy or at the very low or zero rates (i.e., deletion) of gene mutation. We found
that four drug-resistant hamster cell lines reverted to drug sensitivity at rates of about 2–3% per generation, whereas two
closely related lines remained resistant under our conditions. Thus, the karyotypic instability generated by aneuploidy emerges as the
common source of the various levels of drug resistance of cancer cells: minor spontaneous resistances reflect accidental chromosome
assortments, the high selected resistances reflect complex specific assortments, and multidrug resistance reflects new combinations of
unselected genes located on the same chromosomes as selected genes.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.201398998
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2001
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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