title: Inhibition of Wnt-2 and galectin-3 synergistically destabilizes beta-catenin and induces apoptosis in human colorectal cancer cells.
abstract: 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.
authors.affiliation: Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California, San Francisco, CA 94115, USA.
authors.forename: Yihui
authors.initials: Y
authors.lastname: Shi
authors.forename: Biao
authors.initials: B
authors.lastname: He
authors.forename: Kristopher M
authors.initials: KM
authors.lastname: Kuchenbecker
authors.forename: Liang
authors.initials: L
authors.lastname: You
authors.forename: Zhidong
authors.initials: Z
authors.lastname: Xu
authors.forename: Iwao
authors.initials: I
authors.lastname: Mikami
authors.forename: Adam
authors.initials: A
authors.lastname: Yagui-Beltran
authors.forename: Genevieve
authors.initials: G
authors.lastname: Clement
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Lin
authors.forename: Junichi
authors.initials: J
authors.lastname: Okamoto
authors.forename: Dawn T
authors.initials: DT
authors.lastname: Bravo
authors.forename: David M
authors.initials: DM
authors.lastname: Jablons
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism*; D037502:Galectin 3 / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D051154:Wnt2 Protein / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D037502:Galectin 3; D034741:RNA, Small Interfering; D051154:Wnt2 Protein; D051176:beta Catenin