Identification of the proliferative effect of Smad2 and 3 in the TGF β2/Smad signaling pathway using RNA interference in a glioma cell line

Gliomas are the most frequently occurring primary tumor in the brain. The most malignant form of glioma, glioblastoma multiforme (GBM), is characterized by rapid and invasive growth and is restricted to the central nervous system (CNS). The transforming growth factor β2 (TGFβ2)/small mothers against decapentaplegic (Smad) signaling pathway is important, not only in GBM cell metabolism and invasion, but also in GBM cell proliferation. However, the functions of the downstream mediators of the TGFβ2/Smads signaling pathway remain to be fully elucidated. In the present study, short hairpin (sh)RNA interference was used to specifically inhibit the expression of Smad2 and Smad3 in the TGFβ2/Smad signaling pathway to investigate the effects of shRNA on the proliferation of human GBM cells. The results demonstrated that knockdown of either Smad2 or Smad3 enhanced cellular proliferation. Additionally, the key target genes involved in GBM cell proliferation, induced by TGFβ2, were found to be dependent on Smad3, but not Smad2.