Phenolic constituents of virgin olive oil are reported to have antitumor activity. However, the underlying molecular mechanisms and specific target proteins of virgin olive oil remain to be elucidated. Here, we report that dialdehydic form of decarboxymethyl ligstroside aglycone ( p -HPEA-EDA), a phenolic compound of virgin olive oil, inhibits tumor promoter-induced cell transformation in JB6 Cl41 cells and suppress cyclooxygenase-2 (COX-2) and tumorigenicity by adenosine monophosphate-activated protein kinase (AMPK) activation in HT-29 cells. p -HPEA-EDA inhibited 12- O -tetradecanoylphorbol-13-acetate (TPA)-induced phosphorylation of extracellular signal-regulated kinases 1/2 and p90RSK in JB6 Cl41 cells, resulting in the inhibition of cell proliferation, activator protein-1 transactivation and cell transformation promoted by TPA. Moreover, p -HPEA-EDA strongly inhibited the cell viability and COX-2 expression by activation of AMPK activity in HT-29 cells, resulted from depletion of intracellular adenosine triphosphate. p -HPEA-EDA-induced activation of caspase-3 and poly-adenosine diphosphate-ribose polymerase, phosphorylation of p53 (Ser15) and DNA fragmentation in HT-29 cells, leading to apoptosis. Importantly, p -HPEA-EDA suppressed the colony formation of HT-29 cells in soft agar. In contrast, Compound C, an AMPK inhibitor, and Z-DEVD-FMK, a caspase-3 inhibitor, blocked the p -HPEA-EDA-inhibited colony formation in HT-29 cells. In vivo chorioallantoic membrane assay also showed that p -HPEA-EDA-inhibited tumorigenicity of HT-29 cells. These findings revealed that targeted activation of AMPK and inhibition of COX-2 expression by p -HPEA-EDA contribute to the chemopreventive and chemotherapeutic potential of virgin olive oil against colon cancer cells.
Inhibiting the bioactivities of circulating endothelial progenitor cells (EPCs) results in significant inhibition of neovessel formation during tumor angiogenesis. To investigate the potential effect of phloroglucinol as an EPC inhibitor, we performed several in vitro functional assays using $CD34^+$ cells isolated from human umbilical cord blood (HUCB). Although a high treatment dose of phloroglucinol did not show any cell toxicity, it specifically induced the cell death of EPCs under serum free conditions through apoptosis. In the EPC colony-forming assay (EPC-CFA), we observed a significant decreased in the small EPC-CFUs for the phloroglucinol group, implying that phloroglucinol inhibited the early stage of EPC commitment. In addition, in the in vitro expansion assay using $CD34^+$ cells, treatment with phloroglucinol was shown to inhibit endothelial lineage commitment, as demonstrated by the decrease in endothelial surface markers of EPCs including $CD34^+$, $CD34^+/CD133^+$, $CD34^+/CD31^+$ and $CD34^+/CXCR4^+$. This is the first report to demonstrate that phloroglucinol can inhibit the functional bioactivities of EPCs, indicating that phloroglucinol may be used as an EPC inhibitor in the development of biosafe anti-tumor drugs that target tumor angiogenesis.
Sirtuin proteins have emerged as important modulators of several age-associated diseases. These include cancer and diabetes, as well as cardiovascular and neurodegenerative diseases. Among the sirtuin family members, SIRT2 mRNA is strongly expressed. To investigate the pathophysiological significance of SIRT2 as a primary regulator of angiogenesis, we focused on the biological role of SIRT2 under hypoxic conditions, examining the gene expression pattern of sirtuin family members in human umbilical vein endothelial cells (HUVECs). SIRT2 was expressed primarily in the cytoplasm, but it was dynamically trans-localized in the nuclear by hypoxia stimuli. Interestingly, both SIRT2 and the pro-angiogenic factor, VEGF, were up- regulated by hypoxia. A Matrigel assay demonstrated that the HUVECs formed a tube-like structure under hypoxia. The SIRT2 inhibitor, AK-1, significantly decreased the tube-forming activity of the HUVECs under either normoxia or hypoxia conditions. These findings suggest that SIRT2 might be a key regulator of angiogenesis.
Endothelial progenitor cells (EPCs) are derived from hematopoietic stem cells, and have the ability to differentiate into mature endothelial cells and contribute to neovascularization. Glyceollins are a type of phytoalexin produced in soybeans under stress conditions. The aim of this study is to determine the effect of glyceollin treatment on EPCs during early tumor vasculogenesis.We found that glyceollin treatment significantly decreased the number of EPC colony-forming units in human cord blood-derived AC133⁺ cells and mouse bone-marrow-derived c-Kit⁺/Sca-1⁺/Lin⁻ cells. Glyceollin treatment diminished the number of lineage-committed EPC cells in a dose-dependent manner (1-20 μM). Glyceollin treatment inhibited EPC migration, tube formation and the mRNA expression of angiopoietin-1 (Ang-1), Tie-2, stromal-derived factor-1 (SDF-1), C-X-C-chemokine receptor-4 (CXCR4), and endothelial nitric oxide synthase (eNOS) in cultured EPCs. Glyceollin treatment suppressed activation of Akt, Erk, and eNOS induced by SDF-1α or vascular endothelial growth factor (VEGF). Treatment with 10 mg/kg glyceollins significantly reduced the number of tumor-induced circulating EPCs and the incorporation of EPCs into neovessels in bone marrow transplanted mice.These results suggest that glyceollins inhibit the function of EPCs in tumor neovascularization. Glyceollins from soybean elicitation could be beneficial in prevention of cancer development via vasculogenesis.
Notch signaling is involved in cell fate decisions during murine vascular development and hematopoiesis in the microenvironment of bone marrow. To investigate the close relationship between hematopoietic stem cells and human endothelial progenitor cells (EPCs) in the bone marrow niche, we examined the effects of Notch signals [Jagged-1 and Delta-like ligand (Dll)-1] on the proliferation and differentiation of human CD133+ cell-derived EPCs. We established stromal systems using HESS-5 murine bone marrow cells transfected with human Jagged-1 (hJagged-1) or human Dll-1 (hDll-1). CD133+ cord blood cells were co-cultured with the stromal cells for 7 days, and then their proliferation, differentiation, and EPC colony formation was evaluated. We found that hJagged-1 induced the proliferation and differentiation of CD133+ cord blood EPCs. In contrast, hDll-1 had little effect. CD133+ cells stimulated by hJagged-1 differentiated into CD31+/KDR+ cells, expressed vascular endothelial growth factor-A, and showed enhanced EPC colony formation compared with CD133+ cells stimulated by hDll-1. To evaluate the angiogenic properties of hJagged-1- and hDll-1-stimulated EPCs in vivo, we transplanted these cells into the ischemic hindlimbs of nude mice. Transplantation of EPCs stimulated by hJagged-1, but not hDll-1, increased regional blood flow and capillary density in ischemic hindlimb muscles. This is the first study to show that human Notch signaling influences EPC proliferation and differentiation in the bone marrow microenvironment. Human Jagged-1 induced the proliferation and differentiation of CD133+ cord blood progenitors compared with hDll-1. Thus, hJagged-1 signaling in the bone marrow niche may be used to expand EPCs for therapeutic angiogenesis.
The development of endothelial progenitor cells (EPCs) is markedly modulated by vascular niche-derived factors for maintaining EPC pool in adult bone marrow. Although SDF-1a/CXCR4 axis have shown to play a critical role in maintaining hematopoietic stem cell (HSC) pool, the precise regulatory mechanism of EPC development remain unclear. In the analysis of tie-2 specific inactivation of CXCR4 in adult mice, we have found that the number of CD34(−/low)/c-kit(+)/Sca-1(+)/Lin(−) or side population (SP) stem cells is profoundly increased. In addition, EPC colony forming capacity of CD34(−)/c-kit(+)/Sca-1(+)/Lin(−) stem cells in endothelial specific CXCR4 null mice are drastically enhanced. Notably, the development of definitive EPC, a late stage of EPC development, is specifically impaired in Tie2cre-CXCR4 null mice, although the colony number of primitive EPCs, an early stage of EPC development, is profoundly increased. EPCs derived from endothelial specific CXCR4 null mice showed showed immatured EPC function, such as migration capacity, proliferation, cell survival. When cultured with SDF-1, niche-derived stem cells gave rise to promoted EPC colony forming capacity. In myocardiac infarction model, we observed the significantly reduced cardiac function,when measured by echocardiography. Furthermore, capillary density was also significantly decreased, as well as induced fibrosis in endothelial specific CXCR4 null mice. In conclusion, the present report clearly showed for the first time that the SDF-1a/CXCR4 axis plays a pivotal role in EPC maturation in special niche, suggesting that the full understanding of EPC development via regulating SDF-1-CXCR4 axis provide a key source of therapeutic tissue regeneration.
'%3e%3cg id='b'%3e%3cpath id='a' stroke='%23000' stroke-width='2' d='M-6-25H6m-12 3H6m-12 3H6'/%3e%3cuse xlink:href='%23a' y='44'/%3e%3c/g%3e%3cpath stroke='%23fff' d='M0 17v10'/%3e%3ccircle r='12' fill='%23cd2e3a'/%3e%3cpath fill='%230047a0' d='M0-12A6 6 0 0 0 0 0a6 6 0 0 1 0 12 12 12 0 0 1 0-24z'/%3e%3c/g%3e%3cg transform='rotate(-123.69)'%3e%3cuse xlink:href='%23b'/%3e%3cpath stroke='%23fff' d='M0-23.5v3M0 17v3.5m0 3v3'/%3e%3c/g%3e%3c/svg%3e)
