Plasminogen activators in endometrial adenocarcinoma

Discordant expression of mRNA and protein for urokinase and tissue plasminogen activators (u-PA, t-PA) in endometrial carcinoma

Tissue samples were obtained from normal (n = 92), hyperplastic (n = 22) and malignant (n = 35) endometria. Urokinase and tissue plasminogen activators (u-PA, t-PA) were assayed in acetate detergent buffer extracts and their mRNAs quantitated in autoradiograms of Northern blots. The tissue content of u-PA was significantly higher in adenocarcinomas compared to normal and hyperplastic endometria. Tumors with poor differentiation and extensive myometrial invasion had the highest levels. The content of t-PA was increased in hyperplastic endometria but not in adenocarcinomas. The tissue content of t-PA was inversely related to clinical stage and loss of differentiation in malignant tumors. In contrast to the protein data, u-PA mRNA was not higher and t-PA mRNA was much lower in malignant compared to benign tumors. Thus, high tumor tissue content of u-PA does not result from transcriptional regulation, and reduction of t-PA mRNA may indicate down-regulation of transcription or possibly reduced mRNA stability. Furthermore, the discrepancy between protein and mRNA for both activators probably indicates up-regulation of the translation process since decreased degradation of activator proteins is a less likely explanation.

Plasminogen activator inhibitors in endometrial adenocarcinoma

BACKGROUND

Plasminogen activators (PA) play an important role in the mediation of pathologic processes, including cancer invasion. Levels of urokinase are increased in malignant endometrium compared with normal endometrium. The role of PA inhibitors (PAI) in the malignant process is not known.

METHODS

PAI-1 (endothelial type inhibitor) and PAI-2 (placental type inhibitor) in extracts of malignant (n = 14) and normal (n = 7) postmenopausal endometrium were measured. The results were correlated with the standard prognostic variables in endometrial carcinoma, namely, stage, histologic grade, depth of myometrial invasion, and estrogen receptor status of the tumor.

RESULTS

PAI-1 was not detectable in normal endometrium and was present in small quantitities (0.11-1.54 ng PAI-1/mg protein) in 4 of 14 specimens of malignant endometrium. PAI-2 was present in 4 of 7 normal and all (14 of 14) malignant endometrial cytosols. PAI-2 levels were higher in Stage II and III compared with Stage I cancers (P < 0.05) and in malignant endometrium that invaded the myometrium to more than half its depth compared with those with less than 50% invasion (P < 0.05). No significant correlation was found between PAI-2 and estrogen receptor levels (r = -0.32).

CONCLUSIONS

Endometrial adenocarcinoma has higher levels of PAI-2 than does normal postmenopausal endometrium. Highest levels of PAI-2 were found in the poorer prognostic categories of endometrial cancer.