Coordinated expression of matrilysin during TPA-induced apoptosis of LNCaP cells: Two parallel processes affected by TPA

Matrix metalloproteinases (MMPs) are upregulated by growth factors and 12-O-tetradecandyl-phorbol-13-acetate (TPA). TPA (10 nM) induced apoptosis in LNCaP cells grown in serum-free medium at high seeding density, and increased mRNA and secreted protein levels for the MMP matrilysin. While the TPA-augmented increase in matrilysin mRNA was seen at 4 h, secreted matrilysin protein levels at 8 h, TPA-induced DNA ladder formation was seen only at 10 h and the TPA-induced apoptosis was detected at 12 h. The sequence of events suggested a functional role for matrilysin in apoptosis. However, when the MMP inhibitor BB-2516 was used (25 μM, with IC₅₀ of 20 nM for matrilysin), there was no effect of BB-2516 on TPA-induced apoptosis in LNCaP cells (P = 0.2072). This observation indicates that MMPs including matrilysin do not play a primary role in TPA-induced apoptosis in LNCaP cells. We conclude that the TPA-induced apoptosis and the regulation of matrilysin (a TPA-response element (TRE)-containing gene), are independent and parallel processes.