SiRNA-mediated Silencing of β-catenin Suppresses Invasion and Chemosensitivity to Doxorubicin in MG-63 Osteosarcoma Cells

Purpose: β-catenin, the chief oncogenic component of the canonical Wnt pathway, is known to be involvedin development of a variety of cancers, but its role in human osteosarcomas is not fully understood. Here weinvestigate the effect of small interfering RNA-mediated β-catenin knockdown on the survival, invasion andchemosensitivity of a human osteosarcoma cell line.
Methods: A siRNA against β-catenin was constructed andtransfected into MG-63 cells. Expression of β-catenin was determined by qRT-PCR and Western blotting. Cellgrowth and apoptosis were assessed in the presence or absence of doxorubicin by MTT and flow cytometry,respectively, cell invasion by transwell assay, and XIAP, Bclxl, nulear P65 and MT1-MMP expression by westernblot and real-time PCR.
Results: Transfection of β-catenin siRNA resulted in decreased expression of β-catenin,suppression of invasion and motility of MG-63 cells and reduced chemosensitivity to doxorubicin in vitro, butlittle change in cell growth and apoptosis. At the same time, down-regulation of MT1-MMP and up-regulationof NF-kappaB activation were observed.
Conclusion: Knock-down of β-catenin gene may decrease the invasionability through down-regulation of MT1-MMP expression and enhance the chemoresistance to doxorubicin viathe NF-kappaB pathway. In contrast to other tumors, β-catenin may not play an oncogenic role in osteosarcomacells.