Elevated hyaluronan concentration without hyaluronidase activation in malignant epithelial ovarian tumors

The concentration and histological distribution of hyaluronan, a tumor promoting extracellular matrix polysaccharide, and the activity of hyaluronidase, a potential source of angiogenic hyaluronan oligosaccharides, were analyzed in malignant epithelial (n = 24), borderline (n = 8), benign epithelial (n = 20), functional cyst (n = 21), and normal (n = 5) tissue samples of human ovary. Hyaluronan concentration increased specifically in cancers (P = 0.001), particularly in grade 3 tumors (>49-fold) and in metastases (>89-fold). Hyaluronan staining in the tissues correlated with hyaluronan concentration (P = 0.002). Hyaluronidase activity slightly decreased from semimalignant through low grade to high grade tumors (P = 0.041). Therefore, hyaluronan accumulation, but not hyaluronidase activation, is associated with the aggressiveness of ovarian epithelial cancer.