Construction and high cytoplasmic expression of a tumoricidal single-chain antibody against hepatocellular carcinoma

BACKGROUND: Hep27 monoclonal (Hep27 Mab) is an antibody against hepatocellular carcinoma. Hep27 Mab itself can inhibit the growth of a hepatocellular carcinoma cell line (HCC-S102). We attempted to produce a single-chain fragment (scFv), a small fragment containing an antigen-binding site of Hep27 Mab, by using DNA-recombinant techniques. RESULTS: The sequences encoding the variable regions of heavy (V(H)) and light (V(L)) chains of a murine Hep27 Mab were linked together by a linker peptide (Gly4Ser)(3) and tagged with a hexa-histidine at the C-terminal; the resultant DNA construct was expressed in E. coli as an insoluble protein. The denatured scFv was refolded and purified by immobilized metal ion affinity chromatography (12 mg/l with a molecular weight of 27 kDa). Hep27scFv exhibited a tumoricidal activity against the HCC-S102 cell as its parental antibody (Hep27 Mab). CONCLUSION: This scFv may be a potential candidate for a targeting agent in HCC immunodiagnosis or immunotherapy.