The effect of mechanical strain on protease production by keratinocytes

Intact skin is under constant tension, transmitted from the underlying dermis, but when tension is lost (i.e. upon wounding) protease activity is upregulated. To investigate the effect of mechanical strain on protease production by both normal and transformed keratinocytes in vitro. Keratinocytes were seeded on to membranes precoated with either type I or type IV collagen. After 48 h medium was replaced with serum-free medium and mechanical strain was applied. Mechanical strain resulted in decreased urokinase-type plasminogen activator (uPA) production by normal human keratinocytes (P < 0.05) but increased production by transformed keratinocytes (P < 0.05) cultured on type I and type IV collagen. Differential production of uPA by normal and transformed keratinocytes is relevant in the context of normal function, wound healing and tumorigenesis.