IDEHU   05542
INSTITUTO DE ESTUDIOS DE LA INMUNIDAD HUMORAL PROF. RICARDO A. MARGNI
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Human leukemic cell lines synthesize hyaluronan to avoid senescence and resist chemotherapy
Autor/es:
LOMBARDIA S.; MASCARO; PAPADEMETRIO D; ALVAREZ E.; HAJOS S
Lugar:
Oklahoma
Reunión:
Simposio; ISHAS; 2013
Institución organizadora:
ISHAS
Resumen:
Hyaluronan (HA) is one of the major components of the extra-cellular matrix. By enzymatic digestion of HA it is possible to obtain fragments of 2-7 disaccharides, hyaluronan oligomers (oHA) that are able to block HA effect (1). Several solid tumors produce high levels of HA which promote survival and multidrug resistance (MDR) (2). These effects have been associated to deregulation of survival pathways, such as PI3K/Akt and MAPK, as well as Pgp activation (3). Up to date, little is known about the role of HA in hematological pathologies. The aim of this work was to determine whether HA or oHA were able to modulate leukemia cells proliferation and their effect on MDR. Besides, receptors and signaling pathways involved were analyzed. For this purpose K562 and Kv562 human leukemic cell lines, sensitive and resistant to Vincristine (VCR), respectively, were used. Both lines cell expressed CD44, RHAMM and also secreted and bound HA. HA treatment increased K562 cell proliferation whereas oHA or VCR induced inhibition. HA effect was reverted by co-treatment with anti-CD44 MAb, Ly294002 (PI3K inhibitor) and UO126 (MEK1/2 inhibitor). HA increased Kv562 cells proliferation, effect that was reverted by anti-RHAMM Ab and Ly294002. Treatment with oHA or VCR failed to modify Kv562 cells growth. We also evaluated PI3K and MEK related proteins phosphorylation by western blot. We found that HA increased whereas oHA decreased the pAkt/Akt ratio on both K562 and Kv562 cell lines. HA also increased while oHA decreased the pERK/ERK ratio only on K562. 4-Methylumbelliferone (4MU) (HA synthesis inhibitor) decresed both cell lines proliferation inducing senescence, decreased pAkt/Akt ratio and pERK/ERK ratio on K562 but only decreased pAkt/Akt ratio on Kv562. HA abolished such effects. To determine if oHA and 4MU were able to sensitize Kv562 to VCR, the effect of oHA or 4MU in addition with VCR was studied. We found that both co-treatments inhibited cell proliferation and induced senescence. oHA+VCR effect on cell growth was reverted by co-treatment with anti-CD44 Mab while 4MU+VCR effect on cell growth as well as on senescence induction was reverted by co-treatment with HA. Besides, oHA and 4MU inhibited Pgp activity. By flow cytometry, we observed that oHA and 4MU inhibited doxorubicine extrusion, effect that was abolished by addition of anti-CD44 Mab and HA, respectively. We conclude that HA induced cell proliferation in both cell lines, on K562 this effect was mediated by CD44 and activation of both PI3K/Akt and MEK/ERK pathways, whereas on Kv562 it was mediated by RHAMM and PI3K/Akt activation. HA synthesis inhibition by 4MU decresed both cells proliferation inducing senescence. Besides, 4MU sensitized Kv562 to the effect of VCR by Pgp inhibition enhancing senescence. Furthermore oHA inhibited K562 proliferation through CD44 as well as Akt and ERK downregulation; oHA also sensitized Kv562 cells to VCR by Pgp inhibition through CD44 inducing senescence. We postulated that HA synthesis would promote leukemia progression through proliferative signals triggered. These findings highlight the potential use of oHA and 4MU as coadjuvants for resistant leukemia treatment.