Paciucci R, Torà M, Díaz V M, Real F X
Unitat de Biologia Cellular i Molecular, Institut Municipal d'Investigació Mèdica, Barcelona, Spain.
Oncogene. 1998 Feb 5;16(5):625-33. doi: 10.1038/sj.onc.1201564.
Plasminogen activators (PAs) play an important role in tumor cell invasion. We have analysed the expression of tissue-type PA (t-PA), urokinase-type PA (u-PA), and their respective receptors, annexin II and u-PAR, in normal and neoplastic cultures of pancreatic cells, as well as in pancreatic tissues, and have examined their role in tumor invasiveness in vitro. Using Northern blotting, Western blotting, and ELISA, t-PA is detected in cultured pancreas cancer cells displaying a well differentiated phenotype but it is undetectable in less differentiated cells and in normal pancreatic cultures. In contrast, u-PA transcripts, protein, and enzymatic activity are detected both in cancer cells and in normal cultures. Higher levels of u-PAR and annexin II are present in cancer cells than in normal cultures and, in SK-PC-1 cells, both receptors are localized in the basolateral membrane. In vitro invasion assays indicate that both t-PA and u-PA contribute to the invasiveness of SK-PC-1 cells through reconstituted extracellular matrix. To determine the relevance of these studies to pancreas cancer, immunohistochemical assays have been used to examine the expression of t-PA, u-PA, and their receptors in normal and neoplastic tissues. t-PA is absent from normal pancreas and from tumor associated pancreatitis, whereas it is detected in the majority of pancreas cancer tissues (16/17). Annexin II is also overexpressed in some tumors (5/13). u-PAR is overexpressed in most tumor samples examined (14/15), while u-PA is weakly detected in a low number of cases (3/14); both u-PAR and u-PA are overexpressed in areas of tumor associated pancreatitis. Indirect evidences indicate that K-ras and p53 mutated proteins can regulate the expression of PAs. In pancreatic cancer we have found an association between codon 12 K-ras mutations and t-PA expression (P=0.04). These results support the contention that, in the exocrine pancreas, activation of t-PA is more specifically associated to neoplastic transformation and to the invasive phenotype, whereas the induction of u-PA/u-PAR system might be more relevant to inflammatory or non-neoplastic events.
纤溶酶原激活剂（PAs）在肿瘤细胞侵袭中起重要作用。我们分析了组织型PA（t-PA）、尿激酶型PA（u-PA）及其各自的受体膜联蛋白II和u-PAR在胰腺细胞的正常培养和肿瘤培养物以及胰腺组织中的表达，并研究了它们在体外肿瘤侵袭中的作用。通过Northern印迹法、Western印迹法和酶联免疫吸附测定（ELISA），在显示高分化表型的培养胰腺癌细胞中检测到t-PA，但在低分化细胞和正常胰腺培养物中未检测到。相反，在癌细胞和正常培养物中均检测到u-PA转录本、蛋白质和酶活性。癌细胞中u-PAR和膜联蛋白II的水平高于正常培养物，并且在SK-PC-1细胞中，两种受体均定位于基底外侧膜。体外侵袭试验表明，t-PA和u-PA都通过重组细胞外基质促进SK-PC-1细胞的侵袭。为了确定这些研究与胰腺癌的相关性，已使用免疫组织化学方法检测正常组织和肿瘤组织中t-PA、u-PA及其受体的表达。正常胰腺和肿瘤相关性胰腺炎中不存在t-PA，而在大多数胰腺癌组织（16/17）中检测到。膜联蛋白II在一些肿瘤中也过表达（5/13）。在所检测的大多数肿瘤样本（14/15）中u-PAR过表达，而在少数病例（3/14）中微弱检测到u-PA；u-PAR和u-PA在肿瘤相关性胰腺炎区域均过表达。间接证据表明，K-ras和p53突变蛋白可调节PAs的表达。在胰腺癌中，我们发现密码子12的K-ras突变与t-PA表达之间存在关联（P = 0.04）。这些结果支持以下观点，即在外分泌胰腺中，t-PA的激活更具体地与肿瘤转化和侵袭性表型相关，而u-PA/u-PAR系统的诱导可能与炎症或非肿瘤性事件更相关。
