Differential expression of the alpha(2)-macroglobulin receptor and the receptor associated protein in normal human endometrium and endometrial carcinoma

Extracellular matrix degradation, mediated by the activation of receptor-bo und proteolytic enzymes, is essential to the process of cellular invasion. Many normal physiological functions such as endometrial remodelling are rel iant on the activation of these surface associated proteolytic enzymes, as are pathological functions such as cancer-cell invasion. The internalizatio n of proteolytic complexes is mediated by the multifunctional clearance rec eptor, alpha(2)-macroglobulin receptor/LRP. The role of LRP and its ligand binding inhibitor, the receptor-associated protein (RAP), in the advancemen t of invasive endometrial carcinoma is unknown. The aim of this study was t o compare the expression of LRP and RAP mRNA in normal endometrium (n = 14) and endometrial carcinoma (n = 33) by semi-quantitative reverse transcript ion-polymerase chain reaction (RT-PCR). Expression of LRP mRNA in normal en dometrium was significantly increased in the secretory phase when compared with proliferative phase endometrium (P < 0.05). The expression of LRP in a ll carcinomas examined was significantly reduced to about 20% of the amount in normal endometrium (P < 0.05), whereas RAP expression was not significa ntly different between endometrium and carcinoma. No significant difference in the level of LRP or RAP expression was observed between carcinoma grade s or stages. In conclusion, we have shown that LRP expression is differenti ally regulated in the normal endometrium during the menstrual cycle and is decreased in invasive endometrial carcinomas.