[Construction and expression of anti-CD3/anti-prostate-cancer bispecific single-chain antibody].

OBJECTIVE

To construct a recombinant vector that expresses anti-CD 3/anti-prostate-cancer bispecific single-chain antibody (BsAb), and study its biological activities and clinical significance.

METHODS

An anti-CD 3/anti-prostate-cancer BsAb was constructed by PCR and molecular biological technique of DNA cloning. The fusion gene, confirmed by sequencing, was subcloned into the pSectag2-B plasmid from the pUC18 vector by digestion with EcoR I and Hind III restriction endonucleases, whose sites exist in both the vectors. Then the recombinant plasmid was transfected into HeLa cells. The expression products in the supernatant were analyzed by both SDS-PAGE and Western blot technique, then were purified with Ni(2+)-NTA superflow affinity chromatography. Its biological activities were examined by flow cytometry (FCM).

RESULTS

A fragment of 1.5 kb was inserted into the pUC18 vector, which was sequenced and verified to be identical with that designed. The expression of anti-CD 3 x anti-prostate-cancer BsAb yielded a soluble protein with an apparent molecular mass of 61 KD. The purification rate of the expressed BsAb was up to 90.537% and the yield of purified BsAb from this procedure was 0.09 mg/ml. The positive binding rates of BsAb to PBMC and to PC-3 cell were 54.1% and 53.7% respectively.

CONCLUSION

The anti-CD 3 x anti-prostate-cancer BsAb thus constructed exhibits beneficial biological activities and may play an important role in the treatment of prostate cancer.