Hollas W, Hoosein N, Chung L W, Mazar A, Henkin J, Kariko K, Barnathan E S, Boyd D
Department of Tumor Biology, M.D. Anderson Cancer Center, Houston, TX 77030.
Thromb Haemost. 1992 Dec 7;68(6):662-6.
We previously reported that extracellular matrix invasion by the prostate cancer cell lines, PC-3 and DU-145 was contingent on endogenous urokinase being bound to a specific cell surface receptor. The present study was undertaken to characterize the expression of both urokinase and its receptor in the non-invasive LNCaP and the invasive PC-3 and DU-145 prostate cells. Northern blotting indicated that the invasive PC-3 cells, which secreted 10 times more urokinase (680 ng/ml per 10(6) cells per 48 h) than DU-145 cells (63 ng/ml per 10(6) cells per 48 h), had the most abundant transcript for the plasminogen activator. This, at least, partly reflected a 3 fold amplification of the urokinase gene in the PC-3 cells. In contrast, urokinase-specific transcript could not be detected in the non-invasive LNCaP cells previously characterized as being negative for urokinase protein. Southern blotting indicated that this was not a consequence of deletion of the urokinase gene. Crosslinking of radiolabelled aminoterminal fragment of urokinase to the cell surface indicated the presence of a 51 kDa receptor in extracts of the invasive PC-3 and DU-145 cells but not in extracts of the non-invasive LNCaP cells. The amount of binding protein correlated well with binding capacities calculated by Scatchard analysis. In contrast, the steady state level of urokinase receptor transcript was a poor predictor of receptor display. PC-3 cells, which were equipped with 25,000 receptors per cell had 2.5 fold more steady state transcript than DU-145 cells which displayed 93,000 binding sites per cell.
我们先前报道过，前列腺癌细胞系PC-3和DU-145对细胞外基质的侵袭取决于内源性尿激酶与特定细胞表面受体的结合。本研究旨在表征非侵袭性LNCaP细胞以及侵袭性PC-3和DU-145前列腺细胞中尿激酶及其受体的表达情况。Northern印迹法表明，侵袭性PC-3细胞分泌的尿激酶（每48小时每10⁶个细胞分泌680 ng/ml）比DU-145细胞（每48小时每10⁶个细胞分泌63 ng/ml）多10倍，其纤溶酶原激活剂的转录本最为丰富。这至少部分反映了PC-3细胞中尿激酶基因有3倍的扩增。相比之下，在先前被鉴定为尿激酶蛋白阴性的非侵袭性LNCaP细胞中未检测到尿激酶特异性转录本。Southern印迹法表明，这并非尿激酶基因缺失的结果。将放射性标记的尿激酶氨基末端片段与细胞表面交联表明，侵袭性PC-3和DU-145细胞的提取物中存在一种51 kDa的受体，而在非侵袭性LNCaP细胞的提取物中则不存在。结合蛋白的量与通过Scatchard分析计算出的结合能力密切相关。相比之下，尿激酶受体转录本的稳态水平并不能很好地预测受体的表达情况。PC-3细胞每个细胞有25,000个受体，其稳态转录本比DU-145细胞多2.5倍，而DU-145细胞每个细胞有93,000个结合位点。
