Hyaluronan _(HA) oligomers sensitize human leukemia cell lines to the effect of vincristine.

LOMPARDÍA SILVINA; PAPADEMETRIO DANIELA; CORDÓ RUSSO ROSALÍA; SIMUNOVICH TANIA; MASCARÓ MARILINA; ERNST GLENDA; MODENUTTI CARLOS; ALVAREZ ELIDA; HAJOS SILVIA

Buenos Aires

Congreso; 1º Congreso Franco Argentino de Inmunología; 2010

SAI ySoc Francaise du immunology

Hyaluronan (HA) is a glycosaminoglycan constituted by repetitive units of N-acetyl-glucosamine and glucuronic acid. By enzymatic digestion of HA it is possible to obtain fragments between 2 to 7 disaccharides called hyaluronan oligomers (oHA) that are able to block HA action. Several tumors produce high levels of HA which promote survival. This effect has been associated to deregulation of survival pathways, such as PI3K/Akt and MAPK. The aim of this work was to determine if oHA sensitize a human resistant cell line to the effect of Vincristine (VCR) and if Pgp mediates this mechanism. For this purpose, we used both K562 (sensitive) and Kv562 (VCR resistant) cell lines. We analyzed the role of oHA and VCR on K562 and Kv562 cell proliferation showing that oHA inhibited 20% and VCR 90% K562 cell proliferation after 72h of treatment (p<0.05 and p<0.01 respectively). No effect was observed for any treatment on Kv562. We also studied the effect of the combination of oHA with VCR to determine if oHA were able to sensitize Kv562 to the effect of VCR. Cells were co-incubated with oHA (100-300mg/ml) plus VCR (0.5-1mM) for 48-72h. We showed that oHA 300mg/ml + VCR 1mM inhibited 30% cell proliferation (p<0.01) after 48h and 72h treatment, only at 72h oHA 100mg/ml + VCR 1mM inhibited 25% Kv562 proliferation. To analyze if PI3K/Akt and MAPK pathways were implicated, we assessed by western blot the level of those proteins. We found that oHA decreased pAkt/Akt ratio on both K562 and Kv562 and decreased pERK/ERK ratio on K562 (p<0.01). Finally, we analyzed if oHA were able to inhibit Pgp. By flow cytometry we observed that oHA inhibited 20% daunorubicine extrusion. This effect was abolished by addition of an antibody against CD44. We conclude that oHA could sensitize Kv562 cells to the effect of VCR through Pgp inhibition and PI3K/Akt modulation. These findings highlighted the potential use of oHA as a coadjuvant for treating resistant leukemia.