Synergism of lymphotoxin and interferon-gamma in the growth inhibition of breast cancer cell line MCF-7

Abstract

The effect was studied of recombinant lymphotoxin (rLT) in combination with interferons (rIFN-alpha , huIFN-beta , and rIFN-gamma ) on the proliferation of the breast cancer cell line MCF-7. Spontaneous [3H]thymidine incorporation of MCF-7 cells ranged up to 190,000 cmp after 72 h. The addn. of high doses of rLT (>100 U/mL) caused a significant growth inhibition, whereas low concns. (<20 U/mL) resulted only in a slight decrease of [3H]thymidine incorporation. Low concns. of both types interferons caused no growth inhibition. The combination of rLT (20 U/mL) and rIFN-gamma (20 U/mL) resulted in a synergistic redn. of [3H]thymidine incorporation, whereas the combination of rLT with rIFN-alpha or huIFN-beta caused only an additive growth inhibition. Thus, type II but not type I interferons cause a synergistic growth inhibition of the MCF-7 cell line.