1,25-dihydroxyvitamin D-3 inhibits proliferation of IMR-90 human fibroblasts and stimulates pyruvate kinase activity in confluent-phase cells

[摘要] This study tested the hypothesis that 1,25-dihydroxyvitamin D-3 (1,25(OH)(2)D-3) plays a role in regulating some aspects of metabolism in IMR-90 normal human fetal lung fibroblasts. Among the enzymes studied, only pyruvate kinase showed a significant increase after treatment of confluent-phase cells with 1,25(OH)(2)D-3 at various concentrations (0.1-100 nM range) for 24 h. A parallel increase in lactate output was observed. Steroid specificity was established by the failure of 10 nM levels of 25-hydroxyvitamin D-3, estradiol-17 beta and progesterone to affect pyruvate kinase activity. The determination of the time course of [H-3]-2-deoxy-D-glucose transport indicated that the hormone did not influence the transmembrane transport system of D-glucose. The addition of the inhibitors cycloheximide and actinomycin D to the culture medium abolished, at least in part, the 1,25(OH)(2)D-3 stimulation of pyruvate kinase activity, suggesting the probable dependence of the hormone effect on cellular RNA and protein synthesis. 1,25(OH)(2)D-3 also affected fibroblast growth and DNA synthesis. Cell number significantly decreased after 2-5 days treatment with 10 nM hormone in comparison with control fibroblasts, and also the incorporation of [H-3]thymidine into DNA decreased after treatment of the cells with 1 and 10 nM hormone for 48 h. In conclusion, these data demonstrate that 1,25(OH)(2)D-3 stimulates pyruvate kinase activity in confluent-phase IMR-90 human fibroblasts by a mechanism probably dependent on de novo protein synthesis, and also affects cell growth and DNA synthesis in sub-confluent-phase cells.

[发布日期] 1995-12-29

[关键词] 1,25-dihydroxyvitamin D-3;IMR-90 human fibroblast;pyruvate kinase;cell proliferation