The effect of 12-0-tetradecanoyl phorbol-13-acetate(TPA), 1, 25 dihydroxy-vitamin D3(DHVD3), dehydroepiandrosterone(DHEA), glucocorticosteroid(GCS) alone or in combination on the degree of cellular differentiation and the level of c-myc
expression
was
assessed in human myelomonocytic leukemic cell line U-937 by morphological observation, flow cytometry and Northern blot hybridization.
1) The TPA-treated U-937 cells showed to be gathered, to shape irregulary and to die, while either DHVD3-, DHEA-, or GCS-treated cells showed no change in the morphology. Among three combinations of TPA and other agents the cells treated with
combination of TPA and DHVD3 were partly changed into long cells.
2) The mean fluorescence intensity of CD14 molecules on the cell surface and the percentage of the CD14+ cells were increased up to 78 66 and 61.2%, respectively in the cells treated with combination of TPA and DHVD3 in comparison with the
control
cells(6.17, 2.9%). The mean fluorescence intensity of CD15 moleules on the cell surface and the percentage of the CD15+ cells were decreased to 147.18 and 17.7%, respectively in the TPA-treated cells in compariosn with the control cells(292.09,
51.3%),
whereas the expression levels of CD15 molecules on the cell surface treated with combined agents showed similar to the cells treated with TPA.
3) Poly(A+)mRNA was extracted from cells treated with various agents alone or in combination for 3 or 18 hours. Northern blot analysis showed that the c-myc expression of treated with TPA alone or combined agents for 3 hours decreased compared
with
control cells, while that of cells treated with combination of TPA and DHVD3 for 18 hour3 decreased significantly among various groups.
4) Control cells and cells treated with various agents showed the similar level of fluorescence intensity for antibody against c-myc protein.
These results indicated that the differentiation of U-937 cells related considerably to the increase of CD14 antigen expression and the decrease of c-myc mRNA production.
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