Análises citogenéticas e expressão da telomerase em sarcoma 180

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The cancer is a result of genetic instability. There are two theorical lines which try to explain this pathology origin, the conventional genetic theories and the chromosomal theory of cancer. A lot of neoplastic cell characteristics cant be explained by the conventional theories and they are explained by the chromosomal theory. The telomerase plays an important role in cancer development, allowing the tumor cells to proliferate without the barriers imposed by the telomeric erosion. It is frequently observed that cancer possesses specific cells responsible by the tumor progression. The purpose of this work was to understand some tumor biology aspects as the telomerase expression, karyotypical response to different types of the cell line maintenance, presence of tumor stem cells and the aneuploidy role in the tumor progression. The sarcoma 180 cell line has an heterogeneous cell population, with modal number of 68 chromosomes (tetraploid) and chromosomal number ranging from 16 to 232. The cell line didnt show karyotypical differences concerned to the different types of cellular maintenance and different times of tumor progression. In all the analyzed metaphases it was found marker chromosomes (three metacentric and four micro-chromosomes). The constitutive heterochromatin is A-T rich and its localization is kept in the pericentromeric regions. The NORs are activated at least in one chromosome of the pair, in all the chromosomes with rDNA (2, 4, 8, 10, 11, 12, 15, 16, 17, 18 e 19). In the cell population it was found cells that possess the correct chromosomal combination to perpetuate the tumor. These cells were called tumor stem-cells. The cell line possesses a high telomerase expression allowing the indefinite cell proliferation. The tetraploidy observed in sarcoma 180 was originated by endoreduplication and during the cell line development, it was selected specific chromosomal alterations which give adaptive advantages to the tumor cells.

ASSUNTO(S)

telomerase genetica telomerase caracterização cromossômica sarcoma 180 chromosomic cacterization sarcoma 180 câncer

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