DIFFERENTIAL REGULATION OF MMP-2 AND MMP-9 GELATINASES IN CULTURED HUMAN KERATINOCYTES

Background: Among matrix metalloproteinases (MMPs), MMP-2 and MMP-9 ar e considered to play important roles in the tissue metabolism. Objecti ve: To study the production of MMP-2 and MMP-9 in cultured keratinocyt es. Methods: We examined the effect of cell passage number and cell di fferentiation on these enzymes by zymography and immunocytochemistry. Results: Both MMP-2 and MMP-9 gelatinases were detected in keratinocyt e-conditioned media using zymography. The level of MMP-2 in the medium decreased after sequential passage, whereas MMP-9 was detected at a c onstant level. Treatment of keratinocytes with Ca2+, a potent stimulat or for cell differentiation, induced secretion of MMP-9, which was con firmed immunocytochemically. Inversely, treatment with retinoic acid, which inhibits cell differentiation, increased the level of MMP-2. Con clusion: These results suggest that keratinocytes regulate their secre tion of MMP-2 and MMP-9 gelatinase in distinct and independent pattern s during differentiation.