CD44 AND RHAMM AS KEY PLAYERS IN HA-MEDIATED GLIOBLASTOMA MIGRATION

PIBUEL M; POODTS D; DIAZ, M; MOLINARI Y; AMOIA S; FRANCO P; HAJOS S; LOMPARDÍA S

virtual

Congreso; Hyaluronan Meeting 2021; 2021

ISHAS

Glioblastoma is the most common primary tumor of the central nervous system (CNS) and theaverage patient?s survival is 14 months(1, 2). Migration and invasion are strongly associated withhigh mortality(2). Hyaluronan (HA) is the main component in the CNS extracellular matrix(3, 4)and is crucial in GBM progression. It mainly interacts with CD44 and RHAMM and activatesseveral signaling pathways, such as MAPK, which makes it key for migration and invasionprocesses(5?7). This work aimed to demonstrate the implication of HA, its receptors andERK/pERK in the migration of GBM cells. For this purpose, the human GBM cell lines U251 andLN229 were used to evaluate migration by wound healing assay after treatments with lowmolecular mass HA (LMM-HA), anti-CD44, anti-RHAMM, U0126 inhibitor and 4-methylumbelliferone (4MU). Results show that LMM-HA increased cell migration in both celllines. Furthermore, treatment with anti-RHAMM, anti-CD44 or both did not modify the migration.Unexpectedly, when cells were treated with LMM-HA in presence of each or both antibodies, themigration stays at control values. Similar results were found when MEK was inhibited by U0126.Considering that 4MU is an HA synthesis inhibitor(8), an ELISA-like assay was performed tocorroborate this in our models. Indeed, 4MU partially diminished HA synthesis on both cell lines.Interestingly, treatment with 4MU decreased cell migration on both cell lines but the co-treatmentwith LMM-HA did not counteract its effects. Furthermore, 4MU modified the expression of CD44,evaluated by western blot, and the localization of RHAMM and pERK, evaluated by flowcytometry and immunofluorescence. All in all, results suggest that the HA-induced migration ismediated by CD44 and RHAMM as well as MEK/ERK signaling pathway. Interestingly, 4MUpartly decreased the synthesis of HA, and its effects on cell migration seem to be independent ofsuch inhibition since the co-treatment with LMM-HA did not modify this parameter. Overall, theeffects of 4MU on CD44 expression and on RHAMM and pERK localization could explain itsindependent effects on GBM migration. Furthermore, the modulation or re-localization of saidmolecules after 4MU treatment would explain why the HA was not able to counteract the effect of4MU on cell migration. Therefore, the reduction of HA synthesis, as well as the modulation of itsreceptors and signaling pathways triggered using 4MU, might be an interesting approach toimprove the GBM therapy.