PD98059, nor  Y294002 had any effect on the accumu ation of these aggrecanases. The  ower  eve s of aggrecanase proteins present in the ce  ysates a so did not change (data not shown). DISCUSSION One of the ear y events associated with OA is the  oss of Rutin aggrecan from the carti age. The data provided herein suggest that transcription and protein secretion of ADAMTS-4 and ADAMTS-5 are stimu ated in bovine articu ar chondrocytes in response to HA o igosaccharide treatment. In addition, HA  igosaccharide treatment resu ted in an increased association of ADAMTS-4 with MT4-MMP, an increased re ease of the C-termina –truncated form of ADAMTS-4 into the conditioned medium of cu tures, and an increase in the aggrecanase-derived ITEGE neoepitope.

A 3 of these events indicate an overa enhancement in aggrecanase enzymatic activity. In this system, the stimu ation of ADAMTS-4 was more pronounced than the stimu ation of Docetaxel ADAMTS-5, which is simi ar to previous reports on I -1–treated menisca  carti age exp ants . The question remains as to how chondrocytes, embedded deep within carti age, sense or detect changes in the composition of the extrace  u ar matrix—changes that require activation of the matrix-repair cyc e. Such repair cyc es cou d be initiated through a re ease of a matrix-bound cytokines, feedback by damaged matrix macromo ecu es, or direct sensing by matrix receptors. Our work has focused on the  atter, examining mechanisms whereby changes in mu tiva ent occupancy of the hya uronan receptor CD44 activate a cyc e(s) of matrix repair. For these studies, sma HA o igosaccharides are used as specific antagonists of CD44 interactions with HA–aggrecan– ink protein comp order Silymarin exes. The HA o igosaccharides were used in the present study to mimic events that might be expected to occur during wear-and-tear of the HA/aggrecan-rich extrace  u ar matrix and the  oss of ce  –matrix interactions.

Disaccharides of HA are too sma to compete for binding of HA to CD44 and serve as an important negative contro  (9). As shown in Figures 1C and D, no stimu ation of ADAMTS-4 or ADAMTS-5 was observed fo  owing treatment with HA disaccharides. Since these disaccharides are derived from the same HA o igosaccharide preparation, this demonstrates that the stimu ation events that were observed were not due to potentia  supplier Kinetin contaminants within the o igosaccharide preparation. A of the stimu atory activity in the HA o igosaccharide preparation was susceptib e to chondroitinase ABC digestion. The use of HA o igosaccharides as competitive antagonists of HA–CD44 interactions is not restricted to carti age research.

In the fie d of cancer bio ogy, HA o igosaccharides have been shown to suppress tumor growth, induce tumor regression, and in some cases, inhibit metastasis (30–34). In these cancer mode s, HA o igosaccharides are used as antagonists to se ective y disrupt professionals HA–CD44 interactions, resu ting in the activation of numerous signa ing pathways. For examp e, HA o igosaccharide treatment of anchorage-independent murine carcinoma ce  s resu ts in an inhibition of PI3K (coup ed with an activation of phosphatase and tension homo og [PTEN]), inhibition of Akt phosphory ation, fo  owed by an inhibition of Bc -2–associated agonist of  death (BAD).