RESUMO
<p><b>OBJECTIVES</b>To obtain high therapeutic effect and low toxicity single-chain immunotoxin against hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>Human mutant tumor necrosis factor-alpha (mTNFalpha) was linked with the 3' end of humanized single-chain Fv against HCC (hscFv25) in pGEX4T-1 vector. The anti-HCC immunotoxin was expressed in Escherichia coli and identified by western blot. The primary tumor regression trial in nude mice bearing HCC was evaluated the targeting therapeutic value of hscFv25-mTNFalpha. The tumor tissues were stained by immunohistochemical with TNFalpha antibody.</p><p><b>RESULTS</b>The expression of single-chain immunotoxin hscFv25-mTNFalpha was 12% of total bacteria proteins. The tumor regression trials of hscFv25-mTNFalpha showed 5/5 effective. It had 2/5 completely remission and 3/5 partly remission. The therapeutic result of hscFv25-mTNFalpha was better than that of mTNFalpha (F=8.70, 0.05). The HCC tissue treated by hscFv25-mTNFalpha expressed TNFalpha positive reaction. The positive granule mainly existed in HCC cytoplasm.</p><p><b>CONCLUSION</b>The single-chain immunotoxin hscFv25-mTNFalpha has high therapeutic effect and low toxicity. It has potentialities for clinical application.</p>