Elucidating the cell signalling modulation of doxorubicin and baicalein in myeloid leukaemia – preliminary studies

The anthracycline doxorubicin (Dox) is an established chemotherapy for myeloid leukaemia (ML) with known adverse side effects, particularly for older patients. Genetic mutations and microenvironment can lead to development of drug resistance and poor prognosis. The flavone baicalein has shown promising anticancer properties with favourable safety. The aim of this study is to determine the effective concentration for baicalein and Dox for further drug combination study.

In silico screening of baicalein binding to previously reported pockets in protein markers associated with ML was performed using PyRx software. Preliminary in vitro cytotoxicity assays in the cell lines K562 (chronic ML), MOLM-13 (acute ML) and U937 (histiocytic lymphoma, myelomonocytes) have been optimised using CyQuant GR after 2-day treatment of cells with varying concentrations of Dox or baicalein.

In silico results predicted the optimal binding conformations of baicalein to apoptosis-related proteins. Dox treatments (0.039 μM - 2.5 μM) presented dose-dependent inverse relationship with viability in all tested cell lines. MOLM-13 presented with highest sensitivity towards Dox (7-fold difference) with significantly lower IC50 (=0.034 μM; p=0.006) compared to K562 (IC50=0.239 μM). For baicalein (1.25 μM - 80 μM), a dose-dependent cytotoxicity was observed if [baicalein]>10 μM with K562 (IC50=22.4 μM) and MOLM-13 (IC50=18.5 μM) presenting similar sensitivity. However, lower sensitivity to baicalein was observed in U937 (IC50=39.3 μM; p<0.0001 compared to other two cell lines).

These are promising preliminary findings on the path to study the possible mechanisms of cell death actions using various flavones in structure-related activities. To further validate these findings, human samples will be obtained. Future work will concentrate on targeting established biomarkers and uncovering the mechanism of action of drug combinations at protein, genetic and epigenetic level in cell signalling pathways such as apoptosis, Wnt, autophagy.