Activation of matrix metalloproteinase-9 (MMP-9) via a converging plasmin/stromelysin-1 cascade enhances tumor cell invasion
Activation of matrix metalloproteinase-9 (MMP-9) via a converging plasmin/stromelysin-1 cascade enhances tumor cell invasion
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DOI：
10.1074/jbc.274.19.13066
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发表时间：
1999-05-07
影响因子：
4.8
通讯作者：
Quigley, JP
中科院分区：
文献类型：
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作者：
Ramos-DeSimone, N;Hahn-Dantona, E;Quigley, JP
基质金属蛋白酶-9在体内组织重塑中可能起着关键的催化作用，但它是由细胞分泌的，是一种稳定的、无活性的酶原，需要激活才能发挥催化功能。许多蛋白水解酶在体外激活原MIMP-9，但天然的激活剂(S)尚不清楚。为了检测基质金属蛋白酶-9在细胞环境中的激活情况，我们使用了人类肿瘤细胞(MDA-MB-231乳腺癌细胞)的培养，这些细胞被诱导产生超过200倍的浓度范围(0.03-8.1 nm)的基质金属蛋白酶-9。诱导培养中金属蛋白酶组织抑制物(TIMPs)的水平在1-4 nM时保持相对稳定。对MDA-MB-231细胞中MMP9的酶原/活性酶状态的定量检测表明，即使在潜在的激活剂存在的情况下，内源性MMP9与TIMP的摩尔比也决定了MMP9前体的激活是否能够进行。当MMP9/TIMP的比值超过1.0时，MMP9的激活进行，但通过纤溶酶和基质分解酶1(MMP3)相互作用的蛋白酶级联进行。纤溶酶是由内源性尿激酶型纤溶酶原激活剂产生的，不是前-基质金属蛋白酶-9的有效激活剂，既不是分泌的原-基质金属蛋白酶-9，也不是与完整细胞相关的极低水平的原-基质金属蛋白酶-9。虽然纤溶酶可以蛋白水解酶处理原-基质金属蛋白酶-9，但这种有限的作用并不产生具有酶活性的基质金属蛋白酶-9，也不会使基质金属蛋白酶-9更容易被激活。然而，纤溶酶在从外源添加的前基质金属蛋白酶-3中产生活性基质金属蛋白酶-3(基质分解酶-L)是非常有效的。活化的基质金属蛋白酶-3成为92-kDa原-基质金属蛋白酶-9的有效激活剂，产生一种在溶液中具有酶活性的82-kDa物种，代表了高达50-75%的酶原转化率。活化的基质金属蛋白酶-9增强了培养细胞的侵袭表型，因为它们降解细胞外基质和横向基底膜的能力在酶原激活后显著增加。这种增强的组织重塑能力是由于激活了基质金属蛋白酶-9，这是通过使用特定的抗基质金属蛋白酶-9阻断的单抗来证明的。
Matrix metalloproteinase-g (MMP-9) may play a critical catalytic role in tissue remodeling in vivo, but it is secreted by cells as a stable, inactive zymogen, pro MMP-9, and requires activation for catalytic function. A number of proteolytic enzymes activate pro-MIMP-9 in vitro, but the natural activator(s) of MMP-9 is unknown. To examine MMP-9 activation in a cellular setting we employed cultures of human tumor cells (MDA-MB-231 breast carcinoma cells) that were induced to produce MMP-9 over a 200-fold concentration range (0.03-8.1 nM). The levels of tissue inhibitors of metalloproteinase (TIMPs) in the induced cultures remain relatively constant at 1-4 nM. Quantitation of the zymogen/active enzyme status of MMP-9 in the MDA-MB-231 cultures indicates that even in the presence of potential activators, the molar ratio of endogenous MMP-9 to TIMP dictates whether pro-MMP-9 activation can progress. When the MMP-9/TIMP ratio exceeds 1.0, MMP-9 activation progresses, but through an interacting protease cascade involving plasmin and stromelysin 1 (MMP-3). Plasmin, generated by the endogenous urokinase-type plasminogen activator, is not an efficient activator of pro-MMP-9, neither the secreted pro-MMP-9 nor the very low levels of pro-MMP-9 associated with intact cells. Although plasmin can proteolytically process pro-MMP-9, this limited action does not yield an enzymatically active MMP-9, nor does it cause the MMP-9 to be more susceptible to activation. Plasmin, however, is very efficient at generating active MMP-3 (stromelysin-l) from exogenously added pro-MMP-3. The activated MMP-3 becomes a potent activator of the 92-kDa pro-MMP-9, yielding an 82-kDa species that is enzymatically active in solution and represents up to 50-75% conversion of the zymogen, The activated MMP-9 enhances the invasive phenotype of the cultured cells as their ability to both degrade extracellular matrix and transverse basement membrane is significantly increased following zymogen activation. That this enhanced tissue remodelling capability is due to the activation of MMP-9 is demonstrated through the use of a specific anti-MMP-9 blocking monoclonal antibody.