TGF-BETA-1 STIMULATION OF CELL LOCOMOTION UTILIZES THE HYALURONAN RECEPTOR RHAMM AND HYALURONAN

TGF-beta is a potent stimulator of motility in a variety of cell types . It has recently been shown that hyaluronan (HA) can directly promote locomotion of cells through interaction with the HA receptor RHAMM. W e have investigated the role of RHAMM and HA in TGF-beta-stimulated lo comotion and show that TGF-beta triggers the transcription, synthesis and membrane expression of the RHAMM receptor and the secretion of HA coincident with the induction of the locomotory response. This was dem onstrated by both incubating cells with exogenous TGF-beta1 and by sti mulating the production of bioactive TGF-beta1 in tumor cells transfec ted with TGF-beta1 under the control of the metallothionein promoter. TGF-beta1-induced locomotion was suppressed by antibodies that prevent ed HA/RHAMM interaction, using polyclonal antibodies to either RHAMM f usion protein or RHAMM peptides, or mAbs to purified RHAMM. Peptides c orresponding to the HA-binding motif of RHAMM also suppressed TGF-beta 1-induced increases in motility rate. Spontaneous locomotion of fibros arcoma cells was blocked by neutralizing secreted TGF-beta with panspe cific TGF-beta antibodies and by inhibition of TGF-beta1 secretion wit h antisense oligonucleotides. Polyclonal anti-RHAMM fusion protein ant ibodies and peptide from the RHAMM HA-binding motif also suppressed th e spontaneous motility rate of fibrosarcoma cells. These data suggest that fibrosarcoma cell locomotion requires TGF-beta, and the pathway b y which TGF-beta stimulates locomotion uses the HA receptor RHAMM and HA.