[Are centrosomal abnormalities correlated to DNA ploidy in breast cancer?]. / Corrélation entre les anomalies centrosomiques et l'ADN-ploïdie dans le cancer du sein.

ADN ploidy was shown to play a role in genomic instability of cancer cells and prognosis. The implication of the centrosome in the cell cycle was also described. Therefore, new prognostic factors could be suggested for a better-tailored therapy. The purpose of this study is to search for correlation between centrosomal abnormality and ADN ploidy in breast cancer. Cell prints were prepared from cell culture of mesothelial ascitis, fibroblast cell line MRC5 and breast cancer cell lines MCF7 and T47D. Fresh cell prints were also obtained from cases with invasive carcinoma. The centrosome was labelled by an indirect immunofluorescence assay using anti-γ-tubulin antibody and F(ab')(2) FITC before quantification with fluorescence microscopy. ADN ploidy was scored with DNA index obtained by means of flux cytometry. The normal mesothelial cells (94% of cells with only one centrosome) and the diploid cell line MRC5 (68% of cells with two centrosomes) were used as controls. DNA ploidy was found to be correlated with centrosomal abnormality in MCF7 cell line (64% of cells had more than three centrosomes) but not in the 10 cases of invasive ductal carcinoma analysed in this study. The absence of correlation between DNA ploidy and centrosomal abnormality in breast cancer samples may be due to the small numbers of cases, the cell prints or tumorigenesis. Correlation analysis of a larger number of cases and types of breast lesions to numerical and morphological abnormalities of the centrosome are ongoing.

Immunolocalization and cell expression of lung resistance-related protein (LRP) in normal and tumoral human respiratory cells.

Lung resistance-related protein (LRP) is an integral part of the multidrug resistance (MDR) phenotype involved in cell resistance toward xenobiotics or chemotherapy. The aim of this study was to compare the intracellular localization and cell expression of LRP in normal bronchial cells and their tumoral counterparts from non-small cell lung cancer (NSCLC). LRP expression was also investigated concurrently with DNA ploidy and chromosome 16 (lrp gene locus) aberrations. Confocal microscopy showed that LRP localization was exclusively intracytoplasmic regardless of the cell type and was never observed in the nuclear pore complex. Flow cytometry demonstrated a similar level of LRP expression in normal bronchial cells and in cancer cells from NSCLC samples. FISH analysis, performed to evaluate the number of chromosome 16 and lrp loci, demonstrated a significant gain of chromosome 16 in DNA aneuploid tumors. Furthermore, we did not find any link between LRP expression and DNA ploidy status or chromosome 16 number. These results suggest that LRP expression observed in NSCLC, maintained through the carcinogenesis process of respiratory cells, is not altered by the increased number of copies of chromosome 16 and probably controlled by mechanisms different from those of MRP1 expression, whereas both proteins are associated with the MDR phenotype.