Durko M, Brodt P
Department of Surgery, McGill University and The Royal Victoria Hospital, Montreal, Quebec, H3A 1A1, Canada.
Biochem Biophys Res Commun. 1998 Jun 18;247(2):342-8. doi: 10.1006/bbrc.1998.8785.
Previously we reported that suppression of type I collagenase synthesis in human melanoma cells with antisense RNA significantly reduced proteolysis of type I and type IV collagen matrices (Durko et al., 1997, Biochim. Biophys. Acta 1356, 271). Because plasmin is a major activator of the type I collagenase, we assessed the impact of type I collagenase suppression on the urokinase/plasmin system of proteolysis. Gel zymography revealed the appearance of two new caseinolytic bands of Mr 81-83000 in conditioned media of type I collagenase-depleted, but not of wild-type cells and these were identified as plasmin bands. This increased extracellular plasmin activity coincided with reduced membrane-associated plasminogen levels and decreased expression of the urokinase-type plasminogen activator receptor at both the mRNA (up to 83% reduction) and cell-surface (up to 48% reduction) levels, while urokinase mRNA levels remained unchanged. The results indicate that in these cells the urokinase/plasmin system is regulated by type I collagenase levels.
此前我们报道过，用反义RNA抑制人黑色素瘤细胞中I型胶原酶的合成，可显著降低I型和IV型胶原基质的蛋白水解作用（Durko等人，1997年，《生物化学与生物物理学报》1356卷，第271页）。由于纤溶酶是I型胶原酶的主要激活剂，我们评估了I型胶原酶抑制对尿激酶/纤溶酶蛋白水解系统的影响。凝胶酶谱分析显示，在I型胶原酶缺失细胞的条件培养基中出现了两条新的分子量为81 - 83000的酪蛋白水解带，而野生型细胞的条件培养基中未出现，这些带被鉴定为纤溶酶带。这种细胞外纤溶酶活性的增加与膜相关纤溶酶原水平的降低以及尿激酶型纤溶酶原激活剂受体在mRNA水平（最多降低83%）和细胞表面水平（最多降低48%）的表达减少同时出现，而尿激酶mRNA水平保持不变。结果表明，在这些细胞中，尿激酶/纤溶酶系统受I型胶原酶水平的调节。
