Mutant K-ras regulates cathepsin B localization on the surface of human colorectal carcinoma cells
Mutant K-ras regulates cathepsin B localization on the surface of human colorectal carcinoma cells
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DOI：
10.1016/s1476-5586(03)80035-0
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发表时间：
2003-11-01
期刊：
影响因子：
4.8
通讯作者：
Sloane, BF
中科院分区：
文献类型：
--
作者：
Cavallo-Medved, D;Dosescu, J;Sloane, BF
已知组织蛋白酶B蛋白和活性在K-ras突变出现后定位于结肠癌细胞的基底质膜。使用免疫荧光和亚细胞分级技术和两个人结肠癌细胞系-一个突变的K-ras等位基因（HCT 116）和一个女儿线，其中突变的等位基因已被破坏（HKh-2）-我们证明，这些癌细胞的表面上的小窝的组织蛋白酶B的本地化是由突变的K-ras调节。在HCT 116细胞中，更大百分比的组织蛋白酶B分布于小窝，并且组织蛋白酶B的分泌和细胞周（膜相关和分泌的）组织蛋白酶B活性大于在HKh-2细胞中观察到的。先前的研究确定膜联蛋白11四聚体p11的轻链作为肿瘤细胞表面上组织蛋白酶B的结合位点。在HKh-2细胞中，活性K-ras的缺失降低了p11和小窝蛋白-1的稳态水平以及p11向小窝的分布。基于这些结果，我们推测组织蛋白酶B，一种与肿瘤进展有关的蛋白酶，作为该级联的下游组分，在启动小窝中的蛋白水解级联中发挥功能性作用（例如，尿激酶纤溶酶原激活物和尿激酶纤溶酶原激活物受体）也存在于HCT 116小窝中。
Cathepsin B protein and activity are known to localize to the basal plasma membrane of colon carcinoma cells following the appearance of K-ras mutations. Using immunofluorescence and subcellular fractionation techniques and two human colon carcinoma cell lines-one with a mutated K-ras allele (HCT 116) and a daughter line in which the mutated allele has been disrupted (HKh-2)-we demonstrate that the localization of cathepsin B to caveolae on the surface of these carcinoma cells is regulated by mutant K-ras. In HCT 116 cells, a greater percentage of cathepsin B was distributed to the caveolae, and the secretion of cathepsin B and pericellular (membrane-associated and secreted) cathepsin B activity were greater than observed in HKh-2 cells. Previous studies established the light chain of annexin 11 tetramer, p11, as a binding site for cathepsin B on the surface of tumor cells. The deletion of active K-ras in HKh-2 cells reduced the steady-state levels of p11 and caveolin-1 and the distribution of p11 to caveolae. Based upon these results, we speculate that cathepsin B, a protease implicated in tumor progression, plays a functional role in initiating proteolytic cascades in caveolae as downstream components of this cascade (e.g., urokinase plasminogen activator and urokinase plasminogen activator receptor) are also present in HCT 116 caveolae.