BackgroundThe 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.MethodsIn 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.ResultsWe 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.ConclusionThe present finding enlighten the relative roles of HA expression on tumor vs. stroma during the progression of tumors.

Down regulation of hyaluronan (HA) at tumour epithelial cells results in the generation of O-HA. Increasing evidence about O-HA biological functions (mainly in vitro) are available, but we lack information of O-HA sizes generated during tumorigenesis and less information is available about their receptor interaction. We used biochemical approaches and identified that tumour cells of different grade possessing heterogeneity in generation of O-HA and specificity towards receptor binding. We identified a new receptor for HA 6-mer that over express in cancer tissue that shows its role in tumour progression. Collectively, simultaneous identification of HA sizes and their receptors could serve as a prognostic marker.

Colorectal cancer (CRC) is the third most common cancer; cancer biomarker discovery is important for disease detection and management. It is known that hyaluronic acid and its receptors are ubiquitously expressed in almost all human tissues. Earlier we have shown that a monoclonal antibody H11B2C2, presently known as UNIVmAb, reactive hyaladherin expressed in multiple human cancers mainly using immunohistochemistry. However, the nature of the antigen and its sequence homology are not known. In the current study, a comprehensive investigation was performed to explore the nature of the antigen and its homology using both biochemical and proteomic analysis. Our results showed that UNIVmAb reactive 57 kDa antigen was overexpressed in advanced grade colorectal cancer tissues compared to benign and its adjacent benign tissues. Biochemical investigations including biotinylated hyaluronic acid-pulldown, Immunoprecipitation, HA-oligo competition experiments confirmed that the UNIVmAb reactive 57 kDa antigen is a member of hyaladherin. Further Proteomic analysis showed that the antigen has homology with IGHG1 (Igγ-1 chain C region), IGg superfamily, and is associated with human serum albumin.