[Construction of carcinoembryonic antigen (CEA) gene vaccine and stable coexpression with an immune adjuvant].

BACKGROUND & OBJECTIVE: Carcinoembryonic antigen (CEA) positive cancers are poorly responded to different kinds of treatments. Gene vaccines are promising in research of gene immunotherapy for these tumors. In this study, a CEA gene vaccine with hIL-2 as an immune adjuvant was constructed into a pVAX1 vector for synchronous expression, so as to explore experimentally a new biotherapy strategy against tumors.

METHODS

Using reverse transcription polymerase chain reaction (RT-PCR), CEA cDNA was obtained from a large intestine carcinoma tissue; its encoded protein was compared with the CEA presented in GenBank using the protein analysis software. The acquired CEA cDNA fragment was linked to hIL-2 cDNA via an IRES site and cloned into the pVAX1 vector. The recombinant plasmid was estimated by CEA luminometry assay and hIL-2 ELISA measurement respectively.

RESULTS

The nucleotide sequences of the target gene fragments of the recombinant plasmid were verified. The acquired CEA sequence is highly homologous with M29540 and M17303 (99.8%) in GenBank; and the PCR sequence of hIL-2 is coincident with the original cDNA (100%) provided. The antigenicity,membrane-spanning segments, signal cleavage sites, secondary structure and 3D structure of the acquired CEA protein were similar to the original proteins of M29540 and M17303 predicted by the protein analysis software. Results showed the recombinant could steadily express CEA antigen and hIL-2 protein synchronously in CHO cells in vitro.

CONCLUSION

The CEA cDNA was obtained from the tumor tissue and the CEA gene vaccine with hIL-2 coexpression was constructed successfully. It has provided a possible method for immunotherapy against CEA positive cancers in vivo.