T. Gorogh et al., DNA-PLOIDY AND PROTEIN-SYNTHESIS IN SQUAMOUS-CELL CARCINOMA CELL-LINES OF THE HEAD AND NECK, Journal of cancer research and clinical oncology, 123(1), 1997, pp. 39-44
Aneuploidy, as abnormal nuclear DNA content, is considered almost posi
tive evidence of malignancy. In this study three diploid and three ane
uploid squamous cell carcinoma (SCC) cell lines were examined for DNA
content by flow cytometry. The DNA indices of the SCC cell lines were
found to range from 1.0 to 2.1. The mitotic activity of the diploid ce
ll lines was 1.6 times higher and the cells were smaller than aneuploi
d cells. To find a molecular basis for these differences, the pattern
of the de-novo synthesized proteins was analyzed by means of [S-35]met
hionine incorporation, electrophoresis, and autoradiography. In all an
euploid SCC cell lines tested in this experiment, the increase of nucl
ear DNA content is associated with the synthesis of a novel protein wi
th a molecular mass of approximate 55 kDa as well as with altered synt
hesis rates of two preexisting proteins (50 kDa and 100 kDa). For dete
rmination of the amino acid uptake in diploid and aneuploid cells, the
accumulation of [S-35]methionine was measured as a function of time b
y liquid scintillation counting. No significant difference was found i
n the uptake rate between diploid and aneuploid cells with the same pr
otein content. However, discrepancies were revealed when equal numbers
of cells with different DNA index were used, suggesting, that protein
turnover is different in diploid and aneuploid SCC cells.