Abstract 928: Combined treatment by manuka honey and metformin inhibited growth and inducted apoptosis in CD133+and CD90+ subpopulation hepatocellular carcinoma cancer stem cells

Abstract

Abstract Manuka honey is well known for its anti-bacterial and wound healing properties but its anticancer role against cancer stem cells (CSC) in hepatocellular carcinoma (HCC) cell lines and the underlying molecular mechanisms remain uninvestigated. Recently, we identified a CSC subpopulation in HCC cell lines characterized by their CD133+ and CD90+ phenotype. The CD133+/ CD90+cells demonstrated a more aggressive phenotype than the CD133-/ CD90- counterpart and formed metastatic lesions in the lung of immunodeficient mice. In order to evaluate the effect of Manuka honey alone or in combined treatment with Metformin, a biguanide that has been widely used to treat type 2 diabetes, on cell viability and apoptosis induction in human HCC cell lines, isolated and identified CD133+/ CD90+subpopulation CSC were used. Cell viability was monitored using an MTT assay. In addition, apoptosis induction was labeled by Annexin V-fluorescein isothiocyanate/propidium iodide and measured using flow cytometry. Western blotting was used to examine the protein expression of p53, Bcl-2, Bax, Bcl-2-associated death promoter (Bad), Bcl-2 homologous antagonist/killer (Bak) and cleaved-caspases-3 and -9. The results of the present study revealed that Manuka honey alone or in combined treatment with Metformin suppressed the cell viability of CD133+/CD90+cells in a concentration-dependent manner and the maximum effect was detected in combined treatment after 24 h. In addition, Manuka honey alone or in combined treatment with Metformin induced a significant apoptosis in the tested cells. Furthermore, it was demonstrated that combined treatment increased the expression of proapoptotic proteins, including p53, Bax, Bad and Bak, while it decreased the protein level of antiapoptotic protein Bcl-2 compared to control, Manuka honey or Metformin alone. Furthermore, the combined treatment strongly inhibited stemness characteristics of CSC subpopulation, colony formation and dramatically inhibited CD133+/CD90+tumor growth in vivo. Our data demonstrated that combined treatment induced apoptosis in CD133+/CD90+ subpopulation through G1 arrest in the cell-cycle and regulating p53/Bcl-2/caspase-3 signaling pathway. In conclusion, our results suggested that Monuka honey alone or combined treatment with Metformin may be a potential treatment for apoptosis induction in CSC and may provide a novel therapeutic model for HCC. Citation Format: Amira S. Fyala, Ahmed S. Sultan. Combined treatment by manuka honey and metformin inhibited growth and inducted apoptosis in CD133+and CD90+ subpopulation hepatocellular carcinoma cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 928. doi:10.1158/1538-7445.AM2017-928