Expression of the hyaluronan receptor RHAMM in endometrial carcinomas suggests a role in tumour progression and metastasis

Purpose: Interactions of hyaluronic acid (HA) with its binding protein RHAMM (receptor for HA-mediated motility) have been proposed as being important in promoting tumour progression and dissemination. This comparative study was designed to investigate the RHAMM expression patterns in endometrial carcinoma. Methods: We examined a series of 89 endometrial carcinomas and 15 normal endometrial tissues by immunohistochemistry, using a RHAMM-specific polyclonal antibody. Expression of RHAMM was assessed according to the pattern and intensity within (overall cytoplasm, center/periphery of tumours) and between the tumours. The staining results were compared to the corresponding clinical data (age, menopause status, histological staining, histological grading, lymph node status). Results: RHAMM-expression was detectable in 58% of the 89 tumours [Histological stage: pT1a (8/12): pT1b (16/37); pT1c (18/26); pT2 (6/9); pT3a (4/5)] and 13% (2/15) of the normal endometrial tissues. The positivity rates for RHAMM were 100% in patients with positive lymph nodes but only 50.7% in patients with negative lymph nodes (P<0.01). Additionally, the expression pattern showed a highly Significant correlation (P<0.01) with the histological grade of the tumours [G1 (6/42), G2 (33/34), G3 (13/13)] and occurrence of lymph node metastases. Conclusions: Our results suggest that RHAMM expression may enhance and improve the invasion and metastasis of endometrial carcinomas.