Abstract 4652: Wide antiproliferative and proapoptotic activity of the natural prenyl-flavonoid Xanthohumol and its derivatives on cancer cells, peripheral blood mononuclear cells, and human primary endothelial cells
Authors: Dallaglio Katiuscia , Fragliasso Valentina , Gallo Cristina , Frazzi Raffaele , Maccari Clara , Rossello Armando , Albini Adriana 
Published: August 2015

Chemo-preventive drugs are molecules able to prevent or retard cancer development and progression. Recently, diet flavonoids have been recognized as chemo- and angio-preventive agents. Among these, Xanthohumol (XN), is the principal prenylated chalcone of the female inflorescence of the hop plant (Humulus lupulus L.) with chemo-/angio-preventive properties. The biological effects of the chalcones mostly depend on their chemical structure, whose variations influence their anti-tumor effects. In order to identify novel potential chemo-/angio-preventive agents, we analyzed the effects of seven synthetic derivatives of XN on tumor and normal cells. We used different tumor cell lines (lymphoma, colon and prostate cancer cell lines) and healthy human primary cells (mononuclear cells isolated from peripheral blood (PBMCs) and umbilical vein endothelial cells (HUVEC)). XN derivatives have a lower IC50 on both cancer and normal cells as compared to XN. XN10 exerts the highest anti-proliferative activity in cancer and normal primary cells and we therefore focused our experiments on this compound in comparison with XN master molecule. Interestingly, the IC50 values for XN10 are two-three fold higher in primary cells than tumor cells, suggesting an anti-tumor effect of XN10 which spares healthy cells both from peripheral blood and the microenvironment. The treatment with XN10 leads to apoptosis as demonstrated in lymphoma cell lines by PARP-1 cleavage and dose-dependent caspase-3 activation. Preliminary data also show that XN downregulates the enzyme cyclooxygenase-1 while inducing a DNA damage as demonstrated by the increase of the specific marker γ-H2AX in the cell lysates treated with the indicated drugs. We then treated both PBMCs and HUVECs with XN and XN10 in a range of 1-20μM for 48 hr. XN10 affects PBMCs and HUVEC cells viability starting at lower doses (1 μM) than the parental molecule. 20μM XN mainly decreases monocyte population whereas XN10 affects both

CD19+/CD20+ and CD14+/CD33+ cells in parallel with the increase of apoptosis and caspase activation. Further, in HUVECs, XN activates AMPK in a time and dose-dependent manner with a peak of activation after 5 minutes of exposure up to 1h, independently from LKB1 activation. Activation of AMPK signalling pathway by XN was confirmed by ACC phosphorylation at Ser-79 at the same timepoints. In this cellular context, XN modulates AMPK downstream target, mTOR and eNOS, particularly inhibiting eNOS phosphorylation. Collectively, our data show that XN and its novel derivative XN10 exert a strong antiproliferative activity on a variety of tumor cell lines and normal cells. XN10 features the strongest pro-apoptotic activity yet causing the most dramatic cytotoxic effect on normal cells. Moreover, XN activity seems to involve AMPK activation, in HUVEC cells.

Citation Format: Katiuscia Dallaglio, Valentina Fragliasso, Cristina Gallo, Raffaele Frazzi, Clara Maccari, Armando Rossello, Adriana Albini. Wide antiproliferative and proapoptotic activity of the natural prenyl-flavonoid Xanthohumol and its derivatives on cancer cells, peripheral blood mononuclear cells, and human primary endothelial cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4652. doi:10.1158/1538-7445.AM2015-4652