engleski

Spontaneous PCC in childhood acute leukemia

The phenomenon of premature chromosome condensation (PCC) is a consequence of the fusion of one mitotic and one interphase cell. The prematurely condensed chromosomes may be single stranded, fragmented or double stranded depending on whether the interphase cell was in the G1, S or G2 phase at the moment of cell fusion. Spontaneous occurrence of PCC has been reported in different type of malignancies such as carcinoma of the bladder, large bowel, breast, cervix and acute myelogenous leukemia in adult. The biological and clinical significance of such observation in the malignant process is not clear. It was suggested, however, that the products of cell fusion are viable and source of genomic heterogeneity of tumor cell population. In this study we investigated the frequency of spontaneous PCC in our group of children with acute leukemia. This investigation included 87 children, 55 children with acute lymphocytic leukemia(ALL) and 32 with acute myelocytic leukemia (AML). Cytogenetic analysis was performed at diagnosis on slides obtained by 24-hour peripheral blood or bone marrow culture without mitogenic stimlation. Spontaneous PCC were observed in 6 (6.8%) patients, three (5.5%) with ALL and three (9.4%) with AML. The frequency of spreads with PCC ranged from 5.5%-12%. All observed PCC chromosomes appeared to be pulverized corresponding to S-PCC. The analysis of acquired chromosome aberration revealed normal diploid karyotype in 4 patients, and the presence of pseudodiploid clone in two children with AML-M5. In investigated samples no polyploid mitotic cells were detected. This study gives additional evidence that cell fusion and spontaneous PCC is common in human malignancies. On the other hand this investigation does not support the idea that cell fusion represents a mechanism for the origin of tumor cell genomic variability at least in childhood leukemia.

PCC; children; ALL

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