CONICET | Buscador de Institutos y Recursos Humanos

Chronic myeloid leukemia (CML) is a myeloproliferative syndrome characterizedby the presence of the Philadelphia chromosome which encodes a constitutivelyactivated tyrosine kinase (BCRABL).The first line treatment for CML consistson BCRABLinhibitors such as Imatinib. Nevertheless, such treatment may leadto the selection of resistant cells. Therefore, it is of great value to find moleculesthat enhance the antiproliferativeeffect of firstlinedrugs. Hyaluronan is themain glycosaminglican of the extracellular matrix which is involved in tumorprogression and multidrug resistance. We have previously demonstrated thatthe inhibition of hyaluronan synthesis by 4methylumbelliferone(4MU) inducessenescence and can revert Vincristine resistance in CML cell lines. However, theeffect of 4MU on Imatinib therapy remains unknown. The aim of this work was todetermine whether the combination of 4MU with Imatinib is able to modulatethe proliferation as well as apoptosis and senescence induction in human CMLcell lines. For this purpose the ATCC cell line K562, and its multidrug resistantderivate, Kv562 were used. Cells were exposed to 4MU, Imatinib or acombination of both. We demonstrated that 4MU and Imatinib cotreatmentabrogated the proliferation of both cell lines. However, such cotreatmentdid notincrease the levels of apoptosis when compared with the treatment with Imatinibalone. For both cell lines the mechanisms of tumor suppression involved wassenescence, since the combination of 4MU and Imatinib arrested the cell cycle and increased senescence associated βgalactosidaseactivity and senescenceassociated heterochromatin foci presence when compared to each drug alone.Moreover, 4MU, Imatinib and 4MU + Imatinib decreased pAkt/Akt ratio in bothcell lines and reduced the pERK/ERK ratio only in K562 cells. These findingshighlight the potential use of 4MU together with Imatinib for CML therapy.