MICROFLUORIMETRIC ANALYSIS OF DYNAMICS OF GENOMIC CHANGES OF CHINESE HUMSTER FIBROBLASTS
CHL V-79 RJK WITH MULTIDRUG RESISTANCE
T. M. Grinchuk,1 I. E. Ushal, I. V. Artsybasheva, M. A. Pavlenko, B. N. Kudryavtsev
Institute of Cytology RAS, St. Petersburg;
1 e-mail: gmdmk@mail.cytspb.rssi.ru
Results of karyological analysis of cells CHL V-79 RJK selected for resistance to ethidium bromide (EB) causing
multidrug resistance (MDR) (line Vebr-5) were compared with the data of microfluorimetric determination of
DNA content in individual chromosomes of the karyotype. The analysis was performed at the 11th and 88th passages.
Karyotyping of Vebr-5 has shown the presence of an additional genetic material (ADM) in the form of homogenously
or differentially stained regions (HSRs and DSRs, respectively) in two chromosomes (Z1 and Z6, loci
1p29-31 and 1q26, respectively). HSRs in Z6, in the region of localization of the wild type of gene mdr, had unstable
length and structure characteristic of morphological markers of amplification of genes of the family mdr. During long
cultivation of Vebr-5 in the presence of EB (88 passages), the instability of HSRs in Z6 increased. Results of microfluorimetric
analysis of Vebr-5 at the 11th passage have shown an increase in the DNA content not only in chromosomes
Z1 and Z6 marked by HSRs, but also in three chromosomes (Z5, Z12 and Z13) that have no visual morphological
changes. The corresponding analysis at the 88th passage has also revealed non-random changes in the DNA content
in four more chromosomes: an increase in Z14, while a decrease in chromosomes 8, Z7, and Z9. A decrease of
the DNA content in chromosomes is considered to be a result of a partial loss of genetic material, while its increase is
a result of its translocation and (or) amplification. Coefficient of variation of the DNA content changes for large chromosomes
amounted to about 9 %. while for small chromosomes it is about 26 %, which indicates that small chromosomes
have greater potential for instability than the large ones. The data obtained not only confirm, but also enlarge
the concept of directions and character of destabilization of the cell genetic apparatus in the process of neoplastic
transformation due to the MDR acquisition by cells.
Key words: additional genetic material, chromosome, DNA content, karyotype instability,
microfluorimetric analysis, morfological markers of amplification, multidrug resistance
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