Modulation of transformed cells by serum amyloid A interaction with TPA

The potential effect of the acute phase protein serum amyloid A (SAA) on the growth of the WISH (U amnion) cell line and a myeloid leukemia cell line (HL-60) was studied. Significant attenuation of U amnion cell proliferation was achieved by 20 μg/ml and 75 μg/ml SAA in a concentration-dependent manner (p < 0.005). These inhibitory levels of SAA are similar to SAA levels in mild acute events or cancer patients, in vivo. SAA by itself caused differentiation of HL-60 cells. Concomitant addition of 12-0-tetradecanoyl phorbol-13-acetate (TPA), 10^-8 M, with SAA to HL-60 cells potentiated the growth inhibitory effect of TPA and enhanced the differentiation of these cells, as assessed by cell adhesion. These results suggest that SAA plays a role in the modulation of transformed cells.