Expression of Hyaluronan in human tumor progression

BACKGROUND The development and progression of human tumors is accompanied by various cellular, biochemical and genetic alterations. These events include tumor cells interaction with extracellular matrix molecules including hyaluronan (HA). Hyaluronan is a large polysaccharide associated with pericellular matrix of proliferating, migrating cells. Its implication in malignant transformation, tumor progression and with the degree of differentiation in various invasive tumors has well accepted. It has been well known the role HA receptors in tumor growth and metastasis in various cancer tissues. Previously we have observed the unified over expression of Hyaluronic Acid Binding Protein (HABP), H11B2C2 antigen by the tumor cells in various types progressing tumor tissues with different grades. However, the poor understanding of relation between HA and HA-binding protein expression on tumor cells during tumor progression as well as the asymmetric observations of the role of HA expression in tumor progression prompted us to examine the degree of HA expression on tumor cells vs. stroma in various types of human tumors with different grades. METHODS In the present study clinically diagnosed tumor tissue samples of different grades were used to screen the histopathological expression of hyaluronan by using b-PG (biotinylated proteoglycan) as a probe and we compared the relative HA expression on tumor cells vs. stroma in well differentiated and poorly differentiated tumors. Specificity of the reaction was confirmed either by pre-digesting the tissue sections with hyaluronidase enzyme or by staining the sections with pre-absorbed complex of the probe and HA-oligomers. RESULTS We show here the down regulation of HA expression in tumor cells is associated with progression of tumor from well differentiated through poorly differentiated stage, despite the constant HA expression in the tumor associated stroma. CONCLUSION The present finding enlighten the relative roles of HA expression on tumor vs. stroma during the progression of tumors.