Inhibition ofWnt-2 and galectin-3 synergistically destabilizes β-catenin and induces apoptosis in human colorectal cancer cells

Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California, San Francisco, CA 94115, USA.
International Journal of Cancer (Impact Factor: 5.09). 09/2007; 121(6):1175-81. DOI: 10.1002/ijc.22848
Source: PubMed


Constitutive activation of the Wnt pathway as a result of APC, AXIN1 or CTNNB1 mutations has been found in most colorectal cancers. For a long time, this aberrant Wnt activation has been thought to be independent of upstream signals. However, recent studies indicate that upstream signals retain their ability to regulate the Wnt pathway even in the presence of downstream mutations. Wnt-2 is well known for its overexpression in colorectal cancer. Galectin-3 (Gal-3), a multifunctional carbohydrate binding protein implicated in a variety of biological functions, has recently been reported to interact with beta-catenin. In this study, we investigated roles of Wnt-2 and Gal-3 in the regulation of canonical Wnt/beta-catenin signaling. We found that siRNA silencing of either Wnt-2 or Gal-3 expression inhibited TCF-reporter activity, decreased cytosolic beta-catenin level and induced apoptosis in human colorectal cancer cells containing downstream mutations. More interestingly, we showed that inhibition of both Wnt-2 and Gal-3 had synergistic effects on suppressing canonical Wnt signaling and inducing apoptosis, suggesting that aberrant canonical Wnt/beta-catenin signaling in colorectal cancer can be regulated at multiple levels. The combined inhibition of Wnt-2 and Gal-3 may be of superior therapeutic advantage to inhibition by either one of them, giving rise to a potential development of novel drugs for the targeted treatment of colorectal cancer.

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    • "Soon after, it was demonstrated that Galectin-3 is a key regulator in the Wnt/β-catenin signaling pathway.83 Successive studies later highlighted the role of Galectin-3 in this pathway in several cancers of epithelial origin such as colorectal cancer,84,85 pancreatic and gastric cancer cells,86,87 breast cancer and tongue cancer.88-90 "
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    ABSTRACT: Galectins are a family of animal lectins comprising 15 members in vertebrates. These proteins are involved in many biological processes including epithelial homeostasis and tumor progression by displaying intracellular and extracellular activities. Hence Galectins can be found either in the cytoplasm or the nucleus, associated with membranes or in the extracellular matrix. Current studies aim at understanding the roles of Galectins in cell-cell and cell-matrix adhesion, cellular polarity and motility. This review discusses recent progress in defining the specificities and mechanisms of action of Galectins as cell regulators in epithelial cells. Physiological, cellular and molecular aspects of Galectin specificities will be treated successively.
    05/2014; 2(3):e29103. DOI:10.4161/tisb.29103
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    • "However, there are contradictory findings regarding the over- or under-expression of galectin-3 in human colorectal cancer. Galectin-3 overexpression was observed in colorectal carcinoma, corresponding to a positive correlation with cancer progression and metastasis [7-9]. Zaia Povegliano et al. have found that a high percentage of galectin-3-stained cells could be observed in the most advanced colon cancer patients and patients with recurrence after surgery and chemotherapy treatment [10]. "
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    ABSTRACT: Multidrug resistance (MDR), an unfavorable factor compromising the treatment efficacy of anticancer drugs, involves the upregulation of ATP binding cassette (ABC) transporters and induction of galectin-3 signaling. Galectin-3 plays an anti-apoptotic role in many cancer cells and regulates various pathways to activate MDR. Thus, the inhibition of galectin-3 has the potential to enhance the efficacy of the anticancer drug epirubicin. In this study, we examined the effects and mechanisms of silencing galectin-3 via RNA interference (RNAi) on the β-catenin/GSK-3β pathway in human colon adenocarcinoma Caco-2 cells. Galectin-3 knockdown increased the intracellular accumulation of epirubicin in Caco-2 cells; suppressed the mRNA expression of galectin-3, β-catenin, cyclin D1, c-myc, P-glycoprotein (P-gp), MDR-associated protein (MRP) 1, and MRP2; and downregulated the protein expression of P-gp, cyclin D1, galectin-3, β-catenin, c-Myc, and Bcl-2. Moreover, galectin-3 RNAi treatment significantly increased the mRNA level of GSK-3β, Bax, caspase-3, and caspase-9; remarkably increased the Bax-to-Bcl-2 ratio; and upregulated the GSK-3β and Bax protein expressions. Apoptosis was induced by galectin-3 RNAi and/or epirubicin as demonstrated by chromatin condensation, a higher sub-G1 phase proportion, and increased caspase-3 and caspase-9 activity, indicating an intrinsic/mitochondrial apoptosis pathway. Epirubicin-mediated resistance was effectively inhibited via galectin-3 RNAi treatment. However, these phenomena could be rescued after galectin-3 overexpression. We show for the first time that the silencing of galectin-3 sensitizes MDR cells to epirubicin by inhibiting ABC transporters and activating the mitochondrial pathway of apoptosis through modulation of the β-catenin/GSK-3β pathway in human colon cancer cells.
    PLoS ONE 11/2013; 8(11):e82478. DOI:10.1371/journal.pone.0082478 · 3.23 Impact Factor
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    • "Because Gal-3 binding to β-catenin is involved in the regulation of the Wnt/β-catenin signaling pathway21,22, we analyzed the relationship between Gal-3 and β-catenin. We found that silencing the Gal-3 gene significantly reduced the protein levels of β-catenin in SCC-4 and CAL27 cells (Figure 3A) (PSCC-4<0.01; "
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    ABSTRACT: Aim: Galectin-3 (Gal-3) is a member of the carbohydrate-binding protein family that contributes to neoplastic transformation, tumor survival, angiogenesis, and metastasis. The aim of this study is to investigate the role of Gal-3 in human tongue cancer progression. Methods: Human tongue cancer cell lines (SCC-4 and CAL27) were transfected with a small-interfering RNA against Gal-3 (Gal-3-siRNA). The migration and invasion of the cells were examined using a scratch assay and BD BioCoat Matrigel Invasion Chamber, respectively. The mRNA and protein levels of β-catenin, Akt/pAkt, GSK-3β/pGSK-3β, MMP-9 in the cells were measured using RT-PCR and Western blotting, respectively. Results: Transient silencing of Gal-3 gene for 48 h significantly suppressed the migration and invasion of both SCC-4 and CAL27 cells. Silencing of Gal-3 gene significantly decreased the protein level of β-catenin, leaving the mRNA level of β-catenin unaffected. Furthermore, silencing Gal-3 gene significantly decreased the levels of phosphorylated Akt and GSK-3β, and suppressed the mRNA and protein levels of MMP-9 in the cells. Conclusion: Our data suggest that Gal-3 mediates the migration and invasion of tongue cancer cells in vitro via regulating the Wnt/β-catenin signaling pathway and Akt phosphorylation.
    Acta Pharmacologica Sinica 10/2012; 34(1). DOI:10.1038/aps.2012.150 · 2.91 Impact Factor
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