Breast cancer is a major cause of cancer-related death in women. BRCA1 tumour-suppressor function is abolished in sporadic breast cancer by down-regulation of the protein level. This down-regulation inversely correlates with tumour grading. BRCA1 is part of a multiprotein complex, which also contains the recombination factor Rad51. Here we describe that in contrast to BRCA1, histological grading of sporadic invasive ductal breast cancer significantly correlates with over-expression of wild-type Rad51. These data suggest that in addition to the absence of the tumour-suppressor protein BRCA1, over-expression of wild-type Rad51 also contributes to the pathogenesis of a significant percentage of sporadic breast cancers and that other mechanisms than mutations must be responsible for this altered expression. Int. J. Cancer 88:907-913, 2000. (C) 2000 Wiley-Liss, Inc.

Zum Thema Das Verständnis für den Mechanismus der Transformation einer Normalzelle zur Tumorzelle und die Suche nach dabei regelhaft ablaufenden, genetischen Veränderungen sind eng mit möglichen Formen therapeutischer Intervention verknüpft. Das Interesse richtet sich besonders auf das Mammkarzinom. Genbedingte, erbliche Dispositionen (BRCA1, BRCA2) sind bekannt, aber bei 80 % aller Mammakarzinome sind spontane Mutationen die Auslöser. Das Mammakarzinom zeigt im Vergleich zu anderen malignen Tumoren histologisch sehr variable Veränderungen. Komplizierte Formen molekulargenetischer Läsionen sind wahrscheinlich. Auch der Einfluß der Sexualhormone spielt eine Rolle. Für ein besseres Verständnis der Abläufe wurde ein Modell der Mehrschrittkarzinogenese entwickelt. Vorläufer- und Frühformen müssen sowohl histologisch als auch molekulargenetisch analysiert werden. Morphologisch sind die proliferativen Läsionen mit Atypien sehr schwer zu unterscheiden vom Karzinom in situ. Bei letzterem liegen zwar zelluläre Merkmale der Malignität, aber noch keine Infiltrationen vor. Bei den invasiven Karzinomen ist die Definition nach der Morphologie nicht immer eindeutig. Um so wichtiger wird die Kenntnis genetischer Veränderungen. Man unterscheidet zwei Typen: Die Proto-Onkogene werden durch Mutationen, Rearrangements oder Amplifikationen aktiviert. Die Tumorsuppressorgene werden durch Mutationen oder Allelverlust deaktiviert. Es gibt Hinweise, daß Onkogenamplifikationen bestimmten histologischen Subtypen zugeordnet werden können. Für die Tumorsuppressorgene wird angenommen, daß angeboren oder hereditär eine Allel bereits inaktiviert ist. Durch ein somatisches Ereignis kommte es zum Verlust der Heterozygotität. Es resultiert eine komplette Inaktivierung. In multiplen Untersuchungen zur Sequenz und den Loci der genetischen Veränderungen soll die Wahrscheinlichkeit einer Progression zum invasiven Wachstum überprüft werden. Möglicherweise sind in histologisch normal erscheinenden Gewebsabschnitten bereits genetische Veränderungen zu finden.

OBJECTIVE:To assess whether various proteolytic factors which are involved in trophoblast invasion show different concentrations in plasma and placenta of patients with HELLP syndrome, pre-/eclampsia and highly pathological Doppler flow measurements but without additional complications (hpD).DESIGN:Case control and observational study; 18 women with HELLP syndrome, 21 with pre-/eclampsia, 13 with hpD, as well as healthy pregnant women (matched pairs); statistical analysis: sign test and Wilcoxon test.RESULTS:Urokinase-type plasminogen activator (uPA), uPA receptor, tissue-type plasminogen activator (tPA), plasminogen activator inhibitor 1 (PAI-1), matrix metalloproteinases MMP-8, MMP-9 and tissue inhibitor of metalloproteinases TIMP-1 were measured by ELISA. PAI-1 plasma levels are significantly elevated in all three groups studied. In HELLP syndrome, tPA and TIMP-1 are also elevated, and in patients with hpD, MMP-8 is increased, whereas MMP-9, and TIMP-1 are lower. In placenta extract, only pre-/eclampsia shows reduced MMP-9 concentrations.CONCLUSIONS:The increased frequency of small-for-gestational-age infants observed in all three study groups is an expression of impaired placental implantation and remodelling processes. These disturbances manifest themselves in the form of changes in some of the factors in plasma and placenta extract that are involved in these processes.

The receptor for urokinase-type plasminogen activator (uPAR) may contribute to the invasive and metastatic capacity of tumor cells by focusing the serine protease urokinase-type plasminogen activator (uPA) to the cell surface. uPA activates plasminogen to plasmin which in turn degrades extracellular matrix proteins or activates other proteases. Mature uPAR is a heavily glycosylated protein of about 284 amino acids attached to the plasma membrane via a glycosyl-phosphatidylinositol (GPI) anchor. A set of different polyclonal uPAR antibodies has been generated in order to investigate the role of uPAR in tumor spreading in more detail. For this purpose, uPAR (lacking the GPI anchor) was expressed in E. coli and Chinese hamster ovary (CHO) cells. Recombinant uPAR from E. coli (corresponding to amino acids 1-284 of human uPAR) was expressed with an N-terminal histidine-tag insertion and purified by nickel chelate affinity chromatography. Soluble uPAR, synthesized by CHO cells (corresponding to amino acids 1-277 of human uPAR), was isolated by ligand (uPA) affinity chromatography. Expression in E. coli led to a nonglycosylated form of uPAR, whereas uPAR produced by CHO cells seemed to be glycosylated to a similar extent as the naturally occurring human form of uPAR (as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Prior to immunization the N-termini of the recombinant uPAR variants were determined by amino acid sequence analysis. Polyclonal antibodies were generated in chickens and purified from egg yolk. The reaction patterns of these antibodies were analyzed by Western blot analyses and flow cytofluorometry.

OBJECTIVE:Impaired trophoblast invasion plays a major role in the development of preeclampsia. Therefore various factors that are involved in invasion were investigated in gestational disease.METHODS:In pregnant women with HELLP-syndrome (n = 18), pre-/eclampsia (n = 21) and highly pathological Doppler flow measurements (hpD) (n = 13), plasma and placental tissue extract concentrations of uPA, uPA-receptor, tPA, PAI-1, MMP-8, MMP-9, TIMP-1, thrombomodulin, and angiogenin were measured using ELISA.RESULTS:In all three collectives, PAI-1 plasma concentrations were significantly higher (p < 0,05) than in normal pregnancies, in patients with HELLP-syndrome, tPA and TIMP-1 plasma levels were also elevated. MMP-9 concentrations in placental tissue extracts were lower in pre-/eclampsia than in normal pregnancies.CONCLUSIONS:Impaired placental implantation and remodelling in gestational disease is reflected by changes in plasma and placental tissue extract concentrations of various factors that are involved in these processes.

Fragestellung: Bei der Entstehung der PrÄeklampsie spielt die StÖrung der Trophoblastinvasion eine wichtige Rolle. Aus diesem Grunde haben wir verschiedene an der Invasion beteiligte Faktoren bei Gestationserkrankungen untersucht. Methoden: Bei Schwangeren mit HELLP-Syndrom (n = 18), Pr-Ä/Eklampsie (n = 21) und hochpathologischen Dopplerbefunden (hpD) (n = 13) wurden im Plasma und Plazentaextrakt uPA, uPA-Rezeptor, tPA, PAI-1, MMP-8, MMP-9, TIMP-1, Thrombomodulin und Angiogenin mittels ELISA gemessen. Ergebnisse: In alien drei Gruppen war PAI-1 im Plasma erhÖht (p < 0,05), bei HELLP-Syndrom auch tPA und TIMP-1. Im Plazentaextrakt war MMP-9 bei Pr-Ä/Eklampsie erniedrigt. Schlußfolgerungen: Die StÖrung der plazentaren Implantations- und UmbauvorgÄnge bei Gestationserkrankungen spiegelt sich in KonzentrationsverÄnderungen einiger an diesen Prozessen beteiligter Faktoren wider.

Various parameters associated with fibrinolysis were examined in plasma and placenta tissue extract in 18 patients with HELLP syndrome (haemolysis, elevated liver enzymes, and low platelet count). A significant increase in plasma concentrations of tPA and PAl-1 was observed in the HELLP patients in comparison to 18 pregnant women of the control group (equal duration of pregnancy). In contrast, there was no difference in plasma concentrations of uPA, uPA-receptor and D-dimer. In placenta tissue extract, significant differences were found just as rarely for uPA, uPA-receptor and PAl-1 as for tPA and D-dimer. Our findings indicate, that endothelial damage with release of tPA may be involved in the pathophysiological pathway of HELLP syndrome. Increased plasma levels of PAl-1 may reflect deficient fibrinolysis resulting in impairment in microcirculation. Clinical relevance of tPA and PAl-1 plasma concentration as possible predictor of hypertensive pregnancy complications will have to be studied further.

Various parameters associated with fibrinolysis were examined in plasma and placenta tissue extract in 18 patients with HELLP syndrome (haemolysis, elevated liver enzymes, and low platelet count). A significant increase in plasma concentrations of tPA and PAl-1 was observed in the HELLP patients in comparison to 18 pregnant women of the control group (equal duration of pregnancy). In contrast, there was no difference in plasma concentrations of uPA, uPA-receptor and D-dimer. In placenta tissue extract, significant differences were found just as rarely for uPA, uPA-receptor and PAl-1 as for tPA and D-dimer. Our findings indicate, that endothelial damage with release of tPA may be involved in the pathophysiological pathway of HELLP syndrome. Increased plasma levels of PAl-1 may reflect deficient fibrinolysis resulting in impairment in microcirculation. Clinical relevance of tPA and PAl-1 plasma concentration as possible predictor of hypertensive pregnancy complications will have to be studied further.