Anti-angiogenic effects of differentiation-inducing factor-1 involving VEGFR-2 expression inhibition independent of the Wnt/β-catenin signaling pathway

<p>Abstract</p> <p>Background</p> <p>Differentiation-inducing factor-1 (DIF-1) is a putative morphogen that induces cell differentiation in <it>Dictyostelium discoideum</it>. DIF-1 inhibits proliferation of various mammalian tumor cells by suppressing the canonical Wnt/β-catenin signaling pathway. To assess the potential of a novel cancer chemotherapy based on the pharmacological effect of DIF-1, we investigated whether DIF-1 exhibits anti-angiogenic effects <it>in vitro </it>and <it>in vivo</it>.</p> <p>Results</p> <p>DIF-1 not only inhibited the proliferation of human umbilical vein endothelial cells (HUVECs) by restricting cell cycle in the G₀/G₁phase and degrading cyclin D1, but also inhibited the ability of HUVECs to form capillaries and migrate. Moreover, DIF-1 suppressed VEGF- and cancer cell-induced neovascularization in Matrigel plugs injected subcutaneously to murine flank. Subsequently, we attempted to identify the mechanism behind the anti-angiogenic effects of DIF-1. We showed that DIF-1 strongly decreased vascular endothelial growth factor receptor-2 (VEGFR-2) expression in HUVECs by inhibiting the promoter activity of human VEGFR-2 gene, though it was not caused by inhibition of the Wnt/β-catenin signaling pathway.</p> <p>Conclusion</p> <p>These results suggested that DIF-1 inhibits angiogenesis both <it>in vitro </it>and <it>in vivo</it>, and reduction of VEGFR-2 expression is involved in the mechanism. A novel anti-cancer drug that inhibits neovascularization and tumor growth may be developed by successful elucidation of the target molecules for DIF-1 in the future.</p

Combined Wnt/β-Catenin, Met, and CXCL12/CXCR4 Signals Characterize Basal Breast Cancer and Predict Disease Outcome

SummaryPrognosis for patients with estrogen-receptor (ER)-negative basal breast cancer is poor, and chemotherapy is currently the best therapeutic option. We have generated a compound-mutant mouse model combining the activation of β-catenin and HGF (Wnt-Met signaling), which produced rapidly growing basal mammary gland tumors. We identified the chemokine system CXCL12/CXCR4 as a crucial driver of Wnt-Met tumors, given that compound-mutant mice also deficient in the CXCR4 gene were tumor resistant. Wnt-Met activation rapidly expanded a population of cancer-propagating cells, in which the two signaling systems control different functions, self-renewal and differentiation. Molecular therapy targeting Wnt, Met, and CXCR4 in mice significantly delayed tumor development. The expression of a Wnt-Met 322 gene signature was found to be predictive of poor survival of human patients with ER-negative breast cancers. Thus, targeting CXCR4 and its upstream activators, Wnt and Met, might provide an efficient strategy for breast cancer treatment

Kinetic Mechanism of the Ca2+-Dependent Switch-On and Switch-Off of Cardiac Troponin in Myofibrils

The kinetics of Ca2+-dependent conformational changes of human cardiac troponin (cTn) were studied on isolated cTn and within the sarcomeric environment of myofibrils. Human cTnC was selectively labeled on cysteine 84 with N-((2-(iodoacetoxy)ethyl)-N-methyl)amino-7-nitrobenz-2-oxa-1,3-diazole and reconstituted with cTnI and cTnT to the cTn complex, which was incorporated into guinea pig cardiac myofibrils. These exchanged myofibrils, or the isolated cTn, were rapidly mixed in a stopped-flow apparatus with different [Ca2+] or the Ca2+-buffer 1,2-Bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid to determine the kinetics of the switch-on or switch-off, respectively, of cTn. Activation of myofibrils with high [Ca2+] (pCa 4.6) induced a biphasic fluorescence increase with rate constants of >2000 s−1 and ∼330 s−1, respectively. At low [Ca2+] (pCa 6.6), the slower rate was reduced to ∼25 s−1, but was still ∼50-fold higher than the rate constant of Ca2+-induced myofibrillar force development measured in a mechanical setup. Decreasing [Ca2+] from pCa 5.0–7.9 induced a fluorescence decay with a rate constant of 39 s−1, which was approximately fivefold faster than force relaxation. Modeling the data indicates two sequentially coupled conformational changes of cTnC in myofibrils: 1), rapid Ca2+-binding (kB ≈ 120 μM−1 s−1) and dissociation (kD ≈ 550 s−1); and 2), slower switch-on (kon = 390s−1) and switch-off (koff = 36s−1) kinetics. At high [Ca2+], ∼90% of cTnC is switched on. Both switch-on and switch-off kinetics of incorporated cTn were around fourfold faster than those of isolated cTn. In conclusion, the switch kinetics of cTn are sensitively changed by its structural integration in the sarcomere and directly rate-limit neither cardiac myofibrillar contraction nor relaxation

Serum vitamin D levels and survival of patients with colorectal cancer: Post-hoc analysis of a prospective cohort study

<p>Abstract</p> <p>Background</p> <p>Recently, serum 25-hydroxyvitamin D (25OHD) levels were shown to be associated with the survival of patients with colorectal cancer. However, 25OHD levels were measured a median of 6 years before diagnosis or were predicted levels. In this study, we directly measured serum 25OHD levels at surgery and examined the association with survival among patients with colorectal cancer.</p> <p>Methods</p> <p>We started a prospective cohort study to find prognostic factors in patients with colorectal cancer from 2003 to 2008 and stored serum samples and clinical data. As part of a post-hoc analysis, serum 25OHD levels were measured by radioimmunoassay. Association between overall survival and serum 25OHD levels were computed using the Cox proportional hazard model adjusted for month of serum sampling as well as age at diagnosis, gender, cancer stage, residual tumor after surgery, time period of surgery, location of tumor, adjuvant chemotherapy and number of lymph nodes with metastasis at surgery. Unadjusted and adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) were determined.</p> <p>Results</p> <p>Serum 25OHD levels were measured in 257 patients. Only 3% had sufficient levels (30 ng/ml and greater). Based on month of blood sampling, an annual oscillation of 25OHD levels was seen, with levels being lower in spring and higher in late summer. Higher 25OHD levels were associated with better overall survival under multi-variate analysis (HR, 0.91: 95% CI, 0.84 to 0.99, <it>P </it>= 0.027).</p> <p>Conclusions</p> <p>These results suggest that higher 25OHD levels at surgery may be associated with a better survival rate of patients with colorectal cancer.</p

Dickkopf1 Regulates Fate Decision and Drives Breast Cancer Stem Cells to Differentiation: An Experimentally Supported Mathematical Model

BACKGROUND: Modulation of cellular signaling pathways can change the replication/differentiation balance in cancer stem cells (CSCs), thus affecting tumor growth and recurrence. Analysis of a simple, experimentally verified, mathematical model suggests that this balance is maintained by quorum sensing (QS). METHODOLOGY/PRINCIPAL FINDINGS: To explore the mechanism by which putative QS cellular signals in mammary stem cells (SCs) may regulate SC fate decisions, we developed a multi-scale mathematical model, integrating extra-cellular and intra-cellular signal transduction within the mammary tissue dynamics. Preliminary model analysis of the single cell dynamics indicated that Dickkopf1 (Dkk1), a protein known to negatively regulate the Wnt pathway, can serve as anti-proliferation and pro-maturation signal to the cell. Simulations of the multi-scale tissue model suggested that Dkk1 may be a QS factor, regulating SC density on the level of the whole tissue: relatively low levels of exogenously applied Dkk1 have little effect on SC numbers, whereas high levels drive SCs into differentiation. To verify these model predictions, we treated the MCF-7 cell line and primary breast cancer (BC) cells from 3 patient samples with different concentrations and dosing regimens of Dkk1, and evaluated subsequent formation of mammospheres (MS) and the mammary SC marker CD44(+)CD24(lo). As predicted by the model, low concentrations of Dkk1 had no effect on primary BC cells, or even increased MS formation among MCF-7 cells, whereas high Dkk1 concentrations decreased MS formation among both primary BC cells and MCF-7 cells. CONCLUSIONS/SIGNIFICANCE: Our study suggests that Dkk1 treatment may be more robust than other methods for eliminating CSCs, as it challenges a general cellular homeostasis mechanism, namely, fate decision by QS. The study also suggests that low dose Dkk1 administration may be counterproductive; we showed experimentally that in some cases it can stimulate CSC proliferation, although this needs validating in vivo

The Biology of Cancer Stem Cells and Its Clinical Implication in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant tumor with limited treatment options in its advanced state. The molecular mechanisms underlying HCC remain unclear because of the complexity of its multi-step development process. Cancer stem cells (CSCs) are defined as a small population of cells within a tumor that possess the capability for self-renewal and the generation of heterogeneous lineages of cancer cells. To date, there have been two theories concerning the mechanism of carcinogenesis, i.e., the stochastic (clonal evolution) model and the hierarchical (cancer stem cell-driven) model. The concept of the CSC has been established over the past decade, and the roles of CSCs in the carcinogenic processes of various cancers, including HCC, have been emphasized. Previous experimental and clinical evidence indicated the existence of liver CSCs; however, the potential mechanistic links between liver CSCs and the development of HCC in humans are not fully understood. Although definitive cell surface markers for liver CSCs have not yet been found, several putative markers have been identified, which allow the prospective isolation of CSCs from HCC. The identification and characterization of CSCs in HCC is essential for a better understanding of tumor initiation or progression in relation to signaling pathways. These markers could be used along with clinical parameters for the prediction of chemoresistance, radioresistance, metastasis and survival and may represent potential targets for the development of new molecular therapies against HCC. This review describes the current evidence for the existence and function of liver CSCs and discuss the clinical implications of CSCs in patients demonstrating resistance to conventional anti-cancer therapies, as well as clinical outcomes. Such data may provide a future perspective for targeted therapy in HCC

Inhibition of StearoylCoA Desaturase Activity Blocks Cell Cycle Progression and Induces Programmed Cell Death in Lung Cancer Cells

Lung cancer is the most frequent form of cancer. The survival rate for patients with metastatic lung cancer is ∼5%, hence alternative therapeutic strategies to treat this disease are critically needed. Recent studies suggest that lipid biosynthetic pathways, particularly fatty acid synthesis and desaturation, are promising molecular targets for cancer therapy. We have previously reported that inhibition of stearoylCoA desaturase-1 (SCD1), the enzyme that produces monounsaturated fatty acids (MUFA), impairs lung cancer cell proliferation, survival and invasiveness, and dramatically reduces tumor formation in mice. In this report, we show that inhibition of SCD activity in human lung cancer cells with the small molecule SCD inhibitor CVT-11127 reduced lipid synthesis and impaired proliferation by blocking the progression of cell cycle through the G1/S boundary and by triggering programmed cell death. These alterations resulting from SCD blockade were fully reversed by either oleic (18:1n-9), palmitoleic acid (16:1n-7) or cis-vaccenic acid (18:1n-7) demonstrating that cis-MUFA are key molecules for cancer cell proliferation. Additionally, co-treatment of cells with CVT-11127 and CP-640186, a specific acetylCoA carboxylase (ACC) inhibitor, did not potentiate the growth inhibitory effect of these compounds, suggesting that inhibition of ACC or SCD1 affects a similar target critical for cell proliferation, likely MUFA, the common fatty acid product in the pathway. This hypothesis was further reinforced by the observation that exogenous oleic acid reverses the anti-growth effect of SCD and ACC inhibitors. Finally, exogenous oleic acid restored the globally decreased levels of cell lipids in cells undergoing a blockade of SCD activity, indicating that active lipid synthesis is required for the fatty acid-mediated restoration of proliferation in SCD1-inhibited cells. Altogether, these observations suggest that SCD1 controls cell cycle progression and apoptosis and, consequently, the overall rate of proliferation in cancer cells through MUFA-mediated activation of lipid synthesis

Constitutive activation of glycogen synthase kinase-3β correlates with better prognosis and cyclin-dependent kinase inhibitors in human gastric cancer

Background: Aberrant regulation of glycogen synthase kinase-3 beta (GSK-3 beta) has been implicated in several human cancers; however, it has not been reported in the gastric cancer tissues to date. The present study was performed to determine the expression status of active form of GSK-3 beta phosphorylated at Tyr(216) (pGSK-3 beta) and its relationship with other tumor-associated proteins in human gastric cancers. Methods: Immunohistochemistry was performed on tissue array slides containing 281 human gastric carcinoma specimens. In addition, gastric cancer cells were cultured and treated with a GSK-3 beta inhibitor lithium chloride (LiCl) for immunoblot analysis. Results: We found that pGSK-3 beta was expressed in 129 (46%) of 281 cases examined, and was higher in the early-stages of pathologic tumor-node-metastasis (P < 0.001). The expression of pGSK-3 beta inversely correlated with lymphatic invasion (P < 0.001) and lymph node metastasis (P < 0.001) and correlated with a longer patient survival (P < 0.001). In addition, pGSK-3 beta expression positively correlated with that of p16, p21, p27, p53, APC, PTEN, MGMT, SMAD4, or KAl1 (P < 0.05), but not with that of cyclin D1. This was confirmed by immunoblot analysis using SNU-668 gastric cancer cells treated with LiCl. Conclusions: GSK-3 beta activation was frequently observed in early-stage gastric carcinoma and was significantly correlated with better prognosis. Thus, these findings suggest that GSK-3 beta activation is a useful prognostic marker for the early-stage gastric cancer.Hirakawa H, 2009, ONCOL REP, V22, P481, DOI 10.3892/or_00000460Dar AA, 2009, ONCOGENE, V28, P866, DOI 10.1038/onc.2008.434Holmes T, 2008, STEM CELLS, V26, P1288, DOI 10.1634/stemcells.2007-0600Wang Q, 2008, CELL DEATH DIFFER, V15, P908, DOI 10.1038/cdd.2008.2Takahashi-Yanaga F, 2008, CELL SIGNAL, V20, P581, DOI 10.1016/j.cellsig.2007.10.018Pan MH, 2007, J AGR FOOD CHEM, V55, P7777, DOI 10.1021/jf071520hShakoori A, 2007, CANCER SCI, V98, P1388, DOI 10.1111/j.1349-7006.2007.00545.xZheng HC, 2007, ANTICANCER RES, V27, P3561Saegusa M, 2007, J PATHOL, V213, P35, DOI 10.1002/path.2198Ma C, 2007, CANCER RES, V67, P7756, DOI 10.1158/0008-5472.CAN-06-4665Forde JE, 2007, CELL MOL LIFE SCI, V64, P1930, DOI 10.1007/s00018-007-7045-7Li YW, 2007, J BIOL CHEM, V282, P21542, DOI 10.1074/jbc.M701978200Ding QQ, 2007, CANCER RES, V67, P4564, DOI 10.1158/0008-5472.CAN-06-1788Kunnimalaiyaan M, 2007, MOL CANCER THER, V6, P1151, DOI 10.1158/1535-7163.MCT-06-0665Soto-Cerrato V, 2007, MOL CANCER THER, V6, P362, DOI 10.1158/1535-7163.MCT-06-0266Cao Q, 2006, CELL RES, V16, P671, DOI 10.1038/sj.cr.7310078Yang CH, 2006, PRECIS AGRIC, V7, P33, DOI 10.1007/s11119-005-6788-0Crew KD, 2006, WORLD J GASTROENTERO, V12, P354Mai W, 2007, ONCOLOGY-BASEL, V71, P297, DOI 10.1159/000106429Tan J, 2005, CANCER RES, V65, P9012, DOI 10.1158/0008-5472.CAN-05-1226Shakoori A, 2005, BIOCHEM BIOPH RES CO, V334, P1365, DOI 10.1016/j.bbrc.2005.07.041Farago M, 2005, CANCER RES, V65, P5792Ghosh JC, 2005, CLIN CANCER RES, V11, P4580Liao XB, 2003, MOL CANCER THER, V2, P1215Lee HS, 2003, J PATHOL, V200, P39, DOI 10.1002/path.1288Doble BW, 2003, J CELL SCI, V116, P1175, DOI 10.1242/jcs.00384Gotoh J, 2003, CARCINOGENESIS, V24, P435Goto H, 2002, ORAL ONCOL, V38, P549Lee HS, 2001, INT J CANCER, V91, P619D`Amico M, 2000, J BIOL CHEM, V275, P32649, DOI 10.1074/jbc.M000643200Endoh Y, 2000, J PATHOL, V191, P257Wu LY, 1998, J NATL MED ASSOC, V90, P410WOODGETT JR, 1984, BIOCHIM BIOPHYS ACTA, V788, P339