Influence of 5-lipoxygenase on in vitro growth of human mammary carcinoma cell line MCF-7.

The aim of this study was to investigate the direct effect of 5-lipoxygenase (5-LO) on the growth of human mammary cancer cells MCF-7 in vitro. Cell growth was measured according to the level of 3H-thymidine incorporation. 5-LO was shown to inhibit 3H-thymidine incorporation. The inhibitory effect was 19, 42 and 78% when administered at concentrations of 0.1, 0.2 or 0.5 U/ml, respectively. Its effect was time- and dose-dependent and was statistically significant at concentrations of 0.2 and 0.5 U/ml. We have also shown that the specific 5-LO inhibitor MK-886 (1 microM) lifts the inhibitory effect of 5-LO (0.2 U/ml). Moreover, when treated with an activator of 5-lipoxygenase calcium ionophore A23187 (10 microM) MCF-7 cells synthesize LTB4. The results of this study are evidence of the role of 5-lipoxygenase in the regulation of human mammary cancer cells growth in vitro.