Inhibitory effect of polyactin A on the DNA, RNA and protein synthesis of tumor cells in vitro

Polyactin A(PAA), a new home-made biological response modifier, had various biological activities. The prescursors of radioactivity uptake assay, which measure the incorporation of ³H-TdR or ³H-UR or ³H-Leu into DNA, RNA or protein by surviving cells, were used to study the effect of PAA on K₅₆₂, HL-60, E₄B₁₁C₉ hybridoma and B₁₆-F10 melanoma cell in vitro. It was found that PAA ranged from 10 to 5000 μg/ml could inhibit the DNA, RNA and protein synthesis in the K₅₆₂, HL-60, E₄B₁₁C9 hybridoma and B₁₆-F₁₀ melanoma cell at different degree. Especially, the RNA synthesis was strong inhibited at large dose. The effect of PAA was not only dose-dependent, but also different from the cell lines. These results suggest that PAA possessed the inhibitory actions of cell growth, which may play an important role in antitumor activity.