Mahbub AA, Le Maitre CL, Haywood-Small SL, Cross NA, Jordan-Mahy N
Umm Al Qura University, KSA
Sheffield Hallam University, UK
Posters & Accepted Abstracts: Oncol Cancer Case Rep
Background: The study aimed to assess the effects of polyphenol when used in combination with doxorubicin and etoposide, and determine whether polyphenols sensitized leukaemia cells, causing cell-cycle arrest, inhibition of cell proliferation and induction of apoptosis. The rationale being that in some solid tumours, polyphenols have been shown to sensitize cells to apoptosis and/or cell-cycle arrest, potentially reducing doses, whilst maintaining efficacy. Method: Quercetin, apigenin, emodin, rhein, cis-stilbene were investigated alone and in combination with etoposide and doxorubicin in two lymphoid (Jurkat and CCRF-CEM) and two myeloid (THP-1 and KG-1a) leukaemia cells lines. Measurements were made of ATP levels (CellTiter-Glo�®assay), cell-cycle progression (propidium iodide (PI) staining and flow cytometry) and apoptosis (NucView-caspase-3 assay and Hoechst 33342/PI staining). The effects of these combinations on the apoptotic pathway (caspases-3, -8 and -9 Glo�®luminescent assays), glutathione levels (GSH-Gloâ�¢-glutathione assay and cell trackerâ�¢ green-5-chloromethylfluorescein-diacetate-glutathione staining) and DNA damage (Alexa Fluor�® 647 Mouse anti- H2AX staining) were also determined. Results: Doxorubicin and etoposide in combination with polyphenols synergistically reduced ATP levels, induced apoptosis and increased S- and/or G2/M-phase cell-cycle arrest in lymphoid leukaemia cell lines. In the myeloid cell lines doxorubicin and etoposide displayed differential effects. Doxorubicin had a synergistic or additive effect when combined with quercetin, apigenin, emodin, and cis-stilbene, but had an antagonistic effect when combined with rhein. Combination treatment caused a synergistic down regulation of glutathione (GSH) levels and increased DNA damage, driving apoptosis via caspase 8 and 9 activation. However, in myeloid cells were an antagonist effect this was associated with an up-regulation of GSH levels, a reduction in DNA damage and apoptosis. Conclusion: Doxorubicin and etoposide activity can be enhanced by polyphenols, particularly in lymphoid leukaemia cells, although effects were strongly dependent on type of cell line, with some interactions were antagonistic in myeloid cell lines.