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6th ESACP Congress, Heidelberg, April 7-11, 1999 |
A155
Alterations in nuclear morphology have long been recognised as a hallmark of
cancer cells, but the molecular bases of these alterations remain sometimes
to be established. We showed previously that multidrug-resistant cancer cells
displayed nuclear texture changes. In this work, two tumoral cell line
variants were studied: the human ovarian carcinoma cell line IGROV1 and the
multidrug-resistant subline OV1-VCR selected with vincristine. We confirmed
by immunocytochemistry, RT-PCR, and Southern blot that OV1-VCR cells
overexpress P-glycoprotein and its corresponding mRNA without mdr1 gene DNA
amplification. Cell smears of these two cell populations were stained with
Feulgen method and analysed by image cytometry. As compared to drug-sensitive
cells, OV1-VCR display a chromatin global decondensation as assessed by
textural features analysis. In order to correlate this decondensation with
alterations in chromatin structure, genomic DNA was extracted from both cell
lines nuclei after treatment with various con centrations of DNase I.
OV1-VCR cells DNA displayed an increased (about 5 fold) DNase I sensitivity,
suggesting an increased chromatin accessibility. To investigate further the
presence of putative DNase I hypersensitive (HS) sites in the vicinity of
the mdr1 gene promoter, genomic DNA from both cell lines was analysed by
Southern blot after digestion with DNase I and restriction enzymes (Hind III,
BamH1, EcoR1, and Kpn1). According to the mdr1 probe (1.3kb) and enzymes
used, no change in DNase HS sites could be visualised.
MULTIDRUG-RESISTANCE IN HUMAN OVARIAN CARCINOMA CELLS IS ASSOCIATED WITH
NUCLEAR TEXTURE CHANGES AND DNASE I HYPERSENSITIVITY
Yatouji S, Trentesaux C, Dufer J
Unité médian, EA2063, IFR53, UFR Pharmacie, University of Reims,
Reims, France