Furanodienone inhibits cell proliferation and survival by suppressing ERα signaling in human breast cancer MCF-7 cells

Estrogen receptor alpha (ERα) plays an important role in the development and progression of breast cancer and thus the attenuation of ERα activities is a promising treatment strategy. Furanodienone is one of the main bioactive chemical components of Rhizoma Curcumae which is commonly used in Chinese medicine for the treatment of cancer. In this study, we investigated the effects of furanodienone on human breast cancer MCF‐7, T47D, and MDA‐MB‐231 cells. Our results showed that furanodienone could inhibit MCF‐7, T47D, and MDA‐MB‐231 cells proliferation in a dose (10–160 µM) dependent manner. ERα‐negative MDA‐MB‐231 cells were less sensitive to furanodienone than ERα‐positive MCF‐7 and T47D cells. Furanodienone could effectively block 17β‐estradiol (E2)‐stimulated MCF‐7 cell proliferation and cell cycle progression and induce apoptosis evidenced by the flow cytometric detection of sub‐G1 DNA content and the appearance of apoptotic nuclei after DAPI staining. Furanodienone specifically down‐regulated ERα protein and mRNA expression levels without altering ERβ expression. Furanodienone treatment inhibited E2‐stimulation of estrogen response element (ERE)‐driven reporter plasmid activity and ablated E2‐targeted gene (e.g., c‐Myc, Bcl‐2, and cyclin D1) expression which resulted in the inhibition of cell cycle progression and cell proliferation, and in the induction of apoptosis. Knockdown of ERα in MCF‐7 cells by ERα‐specific siRNA decreased the cell growth inhibitory effect of furanodienone. These findings suggest that effects of furanodienone on MCF‐7 cells are mediated, at least in part, by inhibiting ERα signaling. J. Cell. Biochem. 112: 217–224, 2011. © 2010 Wiley‐Liss, Inc.     

Niclosamide suppresses cancer cell growth by inducing Wnt co-receptor LRP6 degradation and inhibiting the Wnt/β-catenin pathway

The Wnt/β-catenin signaling pathway is important for tumor initiation and progression. The low density lipoprotein receptor-related protein-6 (LRP6) is an essential Wnt co-receptor for Wnt/β-catenin signaling and represents a promising anticancer target. Recently, the antihelminthic drug, niclosamide was found to inhibit Wnt/β-catenin signaling, although the mechanism was not well defined. We found that niclosamide was able to suppress LRP6 expression and phosphorylation, block Wnt3A-induced β-catenin accumulation, and inhibit Wnt/β-catenin signaling in HEK293 cells. Furthermore, the inhibitory effects of niclosamide on LRP6 expression/phosphorylation and Wnt/β-catenin signaling were conformed in human prostate PC-3 and DU145 and breast MDA-MB-231 and T-47D cancer cells. Moreover, we showed that the mechanism by which niclosamide suppressed LRP6 resulted from increased degradation as evident by a shorter half-life. Finally, we demonstrated that niclosamide was able to induce cancer cell apoptosis, and displayed excellent anticancer activity with IC(50) values less than 1 μM for prostate PC-3 and DU145 and breast MDA-MB-231 and T-47D cancer cells. The IC(50) values are comparable to those shown to suppress the activities of Wnt/β-catenin signaling in prostate and breast cancer cells. Our data indicate that niclosamide is a unique small molecule Wnt/β-catenin signaling inhibitor targeting the Wnt co-receptor LRP6 on the cell surface, and that niclosamide has a potential to be developed a novel chemopreventive or therapeutic agent for human prostate and breast cancer.     

KHC-4 inhibits β-catenin expression in prostate cancer cells

ABSTRACT

KHC-4 is a 2-phenyl-4-quinolone analogue that exhibits anticancer activity. Aberrant activation of β-catenin signaling contributes to prostate cancer development and progression. Therefore, targeting β-catenin expression could be a useful approach to treating prostate cancer. We found that KHC-4 can inhibit β-catenin expression and its signaling pathway in DU145 prostate cancer cells. Treatment with KHC-4 decreased total β-catenin expression and concomitantly decreased β-catenin levels in both the cytoplasm and nucleus of cells. KHC-4 treatment also inhibited β-catenin expression and that of its target proteins, PI3K, AKT, GSK3β and TBX3. We monitored the stability of β-catenin with the proteasomal inhibitor, MG132, in DU145 cells and found that MG132 reversed KHC-4-induced proteasomal β-catenin degradation. We verified CDK1/β-catenin expression in KHC-4 treated DU145 cells. We found that roscovitine treatment reversed cell proliferation by arresting the cell cycle at the G2/M phase and β-catenin expression caused by KHC-4 treatment. We suggest that KHC-4 inhibits β-catenin signaling in DU145 prostate cancer cells.     

Silencing of lncRNA ZFAS1 inhibits malignancies by blocking Wnt/β-catenin signaling in gastric cancer cells

Gastric cancer is a common malignancy with high mortality. Long noncoding RNA (lncRNA) zinc finger antisense (ZFAS)1 is upregulated in gastric cancer specimens compared with the para-carcinoma tissues. The silencing of ZFAS1 inhibited the growth, proliferation, cell cycle progress, migration, invasion and epithelial-mesenchymal transition (EMT), and enhanced the sensitivity to cis-platinum or paclitaxel in SGC7901 cells, as evidenced by the expression changes of proliferating cell nuclear antigen, Cyclin D1, Cyclin E, Cyclin B1, E-cadherin, N-cadherin, vimentin, matrix metalloproteinase (MMP)-2 and MMP-14. The ZFAS1 also activated the Wnt/β-catenin signaling. Subsequently, the ZFAS1 knockdown-induced the inhibition of migration, invasion, EMT and resistance to chemotherapeutic reagens was reversed by the overexpression of β-catenin. In summary, the silencing of ZFAS1 inhibited the growth, proliferation, cell cycle progress, migration, invasion, EMT and chemotherapeutic tolerance by blocking the Wnt/β-catenin signaling in gastric cancer cells.     

Wnt/β-catenin signaling regulates cancer stem cells in lung cancer A549 cells

Wnt/β-catenin signaling plays an important role not only in cancer, but also in cancer stem cells. In this study, we found that β-catenin and OCT-4 was highly expressed in cisplatin (DDP) selected A549 cells. Stimulating A549 cells with lithium chloride (LiCl) resulted in accumulation of β-catenin and up-regulation of a typical Wnt target gene cyclin D1. This stimulation also significantly enhanced proliferation, clone formation, migration and drug resistance abilities in A549 cells. Moreover, the up-regulation of OCT-4, a stem cell marker, was observed through real-time PCR and Western blotting. In a reverse approach, we inhibited Wnt signaling by knocking down the expression of β-catenin using RNA interference technology. This inhibition resulted in down-regulation of the Wnt target gene cyclin D1 as well as the proliferation, clone formation, migration and drug resistance abilities. Meanwhile, the expression of OCT-4 was reduced after the inhibition of Wnt/β-catenin signaling. Taken together, our study provides strong evidence that canonical Wnt signaling plays an important role in lung cancer stem cell properties, and it also regulates OCT-4, a lung cancer stem cell marker.     

Waif1/5T4 inhibits Wnt/β-catenin signaling and activates noncanonical Wnt pathways by modifying LRP6 subcellular localization

Wnt proteins can activate distinct signaling pathways, but little is known about the mechanisms regulating pathway selection. Here we show that the metastasis-associated transmembrane protein Wnt-activated inhibitory factor 1 (Waif1/5T4) interferes with Wnt/β-catenin signaling and concomitantly activates noncanonical Wnt pathways. Waif1 inhibits β-catenin signaling in zebrafish and Xenopus embryos as well as in mammalian cells, and zebrafish waif1a acts as a direct feedback inhibitor of wnt8-mediated mesoderm and neuroectoderm patterning during zebrafish gastrulation. Waif1a binds to the Wnt coreceptor LRP6 and inhibits Wnt-induced LRP6 internalization into endocytic vesicles, a process that is required for pathway activation. Thus, Waif1a modifies Wnt/β-catenin signaling by regulating LRP6 subcellular localization. In addition, Waif1a enhances β-catenin-independent Wnt signaling in zebrafish embryos and Xenopus explants by promoting a noncanonical function of Dickkopf1. These results suggest that Waif1 modulates pathway selection in Wnt-receiving cells.     

Silibinin inhibits expression of HIF-1α through suppression of protein translation in prostate cancer cells

Silibinin is a polyphenolic flavonoid isolated from the milk thistle (Silybum marianum) and is reported to exhibit anticancer properties. Recently, it has been reported that silibinin inhibits hypoxia-inducible factor-1α (HIF-1α) expression in cancer cells. However, the precise mechanism by which silibinin decreases HIF-1 expression is not fully understood. In this study, silibinin inhibited basal and hypoxia induced expression levels of HIF-1α protein in LNCaP and PC-3 prostate cancer cells, while the rate of HIF-1α protein degradation and mRNA levels were not affected. We found that the decrease in HIF-1 protein by silibinin correlated with suppression of de novo synthesis of HIF-1α protein. Silibinin inhibited global protein synthesis coincided with reduction of eIF4F complex formation and induction of phosphorylation of the translation initiation factor 2α (eIF-2α) which can cause inhibition of general protein synthesis. These results suggest that silibinin’s activity to inhibit HIF-1α protein expression is associated with the suppression of global protein translation.     

TRAF4 participates in Wnt/β-catenin signaling in breast cancer by upregulating β-catenin and mediating its translocation to the nucleus

Tumor necrosis factor receptor-associated factor 4 (TRAF4) is upregulated in various subtypes of breast cancers and cell lines; however, the precise functions of TRAF4 are poorly understood. Our objective was to investigate its relationship with β-catenin. TRAF4 participates in several signaling pathways, such as NF-κB and JNK signaling pathways. In this study, we identified β-catenin as a TRAF4-binding protein, have shown that TRAF4 enhanced expression of β-catenin, and found that TRAF4 mediated the translocation of β-catenin from the cytoplasm to the nucleus, thereby facilitating activation of the Wnt signaling pathway in breast cancer.     

Upregulated microRNA-301a in breast cancer promotes tumor metastasis by targeting PTEN and activating Wnt/β-catenin signaling

MicroRNAs (miRNAs) are strongly implicated in many cancers, including breast cancer. Recently, microRNA-301a (miR-301a) has been proved to play a substantial role in gastric cancer, but its functions in the context of breast cancer remain unknown. Here we report that miR-301a was markedly upregulated in primary tumor samples from patients with distant metastases and pro-metastatic breast cancer cell lines. Gain-of-function and loss-of-function studies showed that ectopic overexpression of miR-301a promoted breast cancer cell migration, invasion and metastasis both in vitro and in vivo. Notably, Wnt/β-catenin signaling was hyperactivated in metastatic breast cancer cells that express miR-301a, and mediated miR-301a-induced invasion and metastasis. Furthermore, miR-301a directly targeted and suppressed PTEN, one negative regulator of the Wnt/β-catenin signaling cascade. These results demonstrate that miR-301a maintains constitutively activated Wnt/β-catenin signaling by directly targeting PTEN, which promotes breast cancer invasion and metastasis. Taken together, our findings reveal a new regulatory mechanism of miR-301a and suggest that miR-301a might be a potential target in breast cancer therapy.     

Wnt/β-catenin signaling and disease

The WNT signal transduction cascade controls myriad biological phenomena throughout development and adult life of all animals. In parallel, aberrant Wnt signaling underlies a wide range of pathologies in humans. In this Review, we provide an update of the core Wnt/β-catenin signaling pathway, discuss how its various components contribute to disease, and pose outstanding questions to be addressed in the future.     

Roles of Wnt/β-catenin signaling in the gastric cancer stem cells proliferation and salinomycin treatment

The Wnt1 protein, a secreted ligand that activates Wnt signaling pathways, contributes to the self-renewal of cancer stem cells (CSCs) and thus may be a major determinant of tumor progression and chemoresistance. In a series of gastric cancer specimens, we found strong correlations among Wnt1 expression, CD44 expression, and the grade of gastric cancer. Stable overexpression of Wnt1 increased AGS gastric cancer cells'' proliferation rate and spheroids formation, which expressed CSC surface markers Oct4 and CD44. Subcutaneous injection of nude mice with Wnt1-overexpressing AGS cells resulted in larger tumors than injection of control AGS cells. Salinomycin, an antitumor agent, significantly reduced the volume of tumor caused by Wnt1-overexpressing AGS cells in vivo. This is achieved by inhibiting the proliferation of CD44+Oct4+ CSC subpopulation, at least partly through the suppression of Wnt1 and β-catenin expression. Taken together, activation of Wnt1 signaling accelerates the proliferation of gastric CSCs, whereas salinomycin acts to inhibit gastric tumor growth by suppressing Wnt signaling in CSCs. These results suggest that Wnt signaling might have a critical role in the self-renewal of gastric CSCs, and salinomycin targeting Wnt signaling may have important clinical applications in gastric cancer therapy.     

A diterpenoid derivative 15-oxospiramilactone inhibits Wnt/β-catenin signaling and colon cancer cell tumorigenesis

The Wnt/β-catenin signaling pathway is a highly conserved pathway in organism evolution and regulates many biological processes. Aberrant activation of the Wnt/β-catenin signaling pathway is closely related to tumorigenesis. In order to identify potent small molecules to treat the over-activated Wnt signaling-mediated cancer, such as colon cancer, we established a mammalian cell line-based reporter gene screening system. The screen revealed a diterpenoid derivative, 15-oxospiramilactone (NC043) that inhibits Wnt3a or LiCl-stimulated Top-flash reporter activity in HEK293T cells and growth of colon cancer cells, SW480 and Caco-2. Treatment of SW480 cells with NC043 led to decreases in the mRNA and/or protein expression of Wnt target genes Axin2, Cyclin D1 and Survivin , as well as decreases in the protein levels of Cdc25c and Cdc2. NC043 did not affect the cytosol-nuclear distribution and protein level of soluble β-catenin, but decreased β-catenin/TCF4 association in SW480 cells. Moreover, NC043 inhibited anchorage-independent growth and xenograft tumorigenesis of SW480 cells. Collectively these results demonstrate that NC043 is a novel small molecule that inhibits canonical Wnt signaling downstream of β-catenin stability and may be a potential compound for treating colorectal cancer.