Development of a novel recombinant LHRH fusion protein for therapy of androgen and estrogen dependent cancers.

LHRH based vaccines are promising candidates for therapy of androgen and estrogen dependent cancers. We report in this communication development of a novel recombinant protein vaccine candidate against LHRH. A synthetic gene was designed in which the codon sequence in the LHRH decapeptide was modified by substituting the codon for 6-glycine with that of l-leucine. Further the LHRH(6leu) gene was linked to heat-labile enterotoxin of E. coli (LTB) as carrier. This LHRH(6leu)-LTB gene was cloned into a prokaryotic expression vector under the control of inducible and strong bacteriophage T7 promoter to over-express LHRH(leu) fused to LTB as recombinant protein in E. coli. Recombinant LHRH(leu)-LTB protein of ∼14 kDa size, was purified from inclusion bodies using in-situ refolding on the column and Ni-NTA based immobilized affinity chromatography. Western blot confirmed the immunoreactivity of purified LHRH(leu)-LTB fusion protein with anti-LHRH monoclonal antibody. The vaccine protein was further characterized by mass spectroscopy, circular dichroism and fluorescence spectroscopy. This communication reports a recombinant LHRH fusion protein with potential for blocking of sex hormones production for eventual therapy of sex hormones dependent neoplasms.