Specific inhibition of transforming growth factor-β2 expression in human osteoblast cells by antisense phosphorothioate oligonucleotides

To elucidate the role of endogenous transforming growth factor (TGF)-β2 on human osteoblast cell, antisense phosphorothioate oligonucleotides (S-ODNs) complementary to regions in mRNA of TGF-β2 were synthesized and examined their effects on TGF-β2 production and cell proliferation in a human osteoblast cell line ROS 17/2. Antisense S-ODNs were designated for three different target regions in the mRNA of TGF-β2. Among several antisense S-ODN analyzed, an oligonucleotide (AS-11) complementary to the translation initiation site of mRNA of TGF-β2 demonstrated a selective and strong inhibitory effect on TGF-β2 production in osteoblast cells. Other antisense S-ODNs which were designated for other regions in mRNA of TGF-β2 and one- or three-base mismatched analogs of AS-11 showed little or much less antisense activities than AS-11. Therefore, the most effective target site in mRNA of TGF-β2 is at the initiation codon region. The antisense effects of AS-11 were observed without reduction of levels of mRNA of TGF-β2. Furthermore, the inhibition of TGF-β2 expression by antisense S-ODN appeared to enhance cell proliferation, demonstrating the growth inhibitory effect of autocrine TGF-β2 in osteoblast cells.