title: Uncovering the dual role of RHAMM as an HA receptor and a regulator of CD44 expression in RHAMM-expressing mesenchymal progenitor cells.
abstract: The interaction of hyaluronan (HA) with mesenchymal progenitor cells impacts trafficking and fate after tissue colonization during wound repair and these events contribute to diseases such as cancer. How this interaction occurs is poorly understood. Using 10T½ cells as a mesenchymal progenitor model and fluorescent (F-HA) or gold-labeled HA (G-HA) polymers, we studied the role of two HA receptors, RHAMM and CD44, in HA binding and uptake in non-adherent and adherent mesenchymal progenitor (10T½) cells to mimic aspects of cell trafficking and tissue colonization. We show that fluorescent labeled HA (F-HA) binding/uptake was high in non-adherent cells but dropped over time as cells became increasingly adherent. Non-adherent cells displayed both CD44 and RHAMM but only function-blocking anti-RHAMM and not anti-CD44 antibodies significantly reduced F-HA binding/uptake. Adherent cells, which also expressed CD44 and RHAMM, primarily utilized CD44 to bind to F-HA since anti-CD44 but not anti-RHAMM antibodies blocked F-HA uptake. RHAMM overexpression in adherent 10T½ cells led to increased F-HA uptake but this increased binding remained CD44 dependent. Further studies showed that RHAMM-transfection increased CD44 mRNA and protein expression while blocking RHAMM function reduced expression. Collectively, these results suggest that cellular microenvironments in which these receptors function as HA binding proteins differ significantly, and that RHAMM plays at least two roles in F-HA binding by acting as an HA receptor in non-attached cells and by regulating CD44 expression and display in attached cells. Our findings demonstrate adhesion-dependent mechanisms governing HA binding/ uptake that may impact development of new mesenchymal cell-based therapies.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratories Berkeley, CA, USA ; Palo Alto Research Center (a Xerox Company) Palo Alto, CA, USA.
authors.forename: Mandana
authors.initials: M
authors.lastname: Veiseh
authors.affiliation: Departments of Oncology/Biochemistry/Surgery, Western Schulich School of Medicine, London Regional Cancer Program, Western University London, ON, Canada.
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Leith
authors.affiliation: Departments of Oncology/Biochemistry/Surgery, Western Schulich School of Medicine, London Regional Cancer Program, Western University London, ON, Canada.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Tolg
authors.affiliation: Departments of Oncology/Biochemistry/Surgery, Western Schulich School of Medicine, London Regional Cancer Program, Western University London, ON, Canada.
authors.forename: Sallie S
authors.initials: SS
authors.lastname: Elhayek
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratories Berkeley, CA, USA.
authors.forename: S Bahram
authors.initials: SB
authors.lastname: Bahrami
authors.affiliation: Departments of Oncology/Biochemistry/Surgery, Western Schulich School of Medicine, London Regional Cancer Program, Western University London, ON, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Collis
authors.affiliation: Departments of Oncology/Biochemistry/Surgery, Western Schulich School of Medicine, London Regional Cancer Program, Western University London, ON, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Hamilton
authors.affiliation: Department of Laboratory Medicine and Pathology, Masonic Comprehensive Cancer Center, University of Minnesota Minneapolis, MN, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: McCarthy
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratories Berkeley, CA, USA.
authors.forename: Mina J
authors.initials: MJ
authors.lastname: Bissell
authors.affiliation: Departments of Oncology/Biochemistry/Surgery, Western Schulich School of Medicine, London Regional Cancer Program, Western University London, ON, Canada.
authors.forename: Eva
authors.initials: E
authors.lastname: Turley
keywords: CD44; HMMR; RHAMM; hyaluronan; progenitor