EXPRESSION OF SOME ONCOGENES, MACROMOLECULAR-SYNTHESIS, APOPTOSIS ANDCLONOGENICITY OF LEUKEMIC-CELLS MODIFIED BY MOLECULES PRESENT IN HEMATOPOIETIC-TISSUE

To investigate a possible interrelationship of some fundamental proces ses in leukemic cells, preparations of natural origin have been used a s the tools for manipulation of cellular properties. Lyophylised crude extract from regenerating spleen and its purified fraction added to m ouse leukemia cell cultures rapidly and almost entirely inhibited DNA synthesis in a dose-dependent manner. Total RNA moderate synthesis inh ibition was seen at 4 h and this inhibition increased with time. Prote in synthesis inhibition being minimal at 4 h was observed at 24 h. C-m yc expression was maintained at the same level in the treated and cont rol cells during incubation period and was slightly decreased in treat ed cells at 24 h in comparison with uneffected cells. There were no no ticable changes in c-fos or c-jun expression both in treated and contr ol cells. The level of DNA fragmentation was more pronounced in the tr eated cells after 1 h incubation and coincided with the dissociation o f stopped proliferation and lasting c-myc expression. But later on the re was no discrepancy in the expression of apoptotic process measured by means of apoptotic ladder in treated and uneffected cultures, may b e because of the beginning of RNA and protein synthesis suppression in the former. In contrast, clonogenic potential of leukemic cells was m arkedly reduced after their 24 h treatment. This seemed contradiction may be partially overcome on the basis of understanding of the presenc e of non-clonogenic cells in the analysed cell populations and some pe culiarities of apoptotic process in cultured cells. In any case, regul atory molecules present in repairing hematopoietic tissue may influenc e leukemic cell properties.