TGF-α antisense gene therapy inhibits head and neck squamous cell carcinoma growth in vivo

Unlike normal mucosal squamous epithelial cells, head and neck squamous cell carcinomas (HNSCCs) overexpress TGF-α mRNA and protein which is required to sustain the proliferation of HNSCC cells in vitro. To determine whether TGF-α expression contributes to tumor growth in vivo, cationic liposome-mediated gene transfer was used to deliver an antisense expression construct targeting the human TGF-a gene into human head and neck tumor cells, grown as subcutaneous xenografts in nude mice. The TGF-a antisense gene was immediately detected in the cytoplasm of the tumor cells, translocated to the nucleus by 12 h and remained localized to the nucleus for up to 3 days. Direct inoculation of the TGF-a antisense (but not the corresponding sense) construct into established HNSCC tumors resulted in inhibition of tumor growth. Sustained antitumor effects were observed for up to 1 year after the treatments were discontinued. Down-modulation of TGF-a was accompanied by increased apoptosis in vivo. These experiments indicate that interference with the TGF-α/EGFR autocrine signaling pathway may be an effective therapeutic strategy for cancers which overexpress this ligand/receptor pair.