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

- A novel recombinant LHRH fusion protein LHRH(6leu)-LTB is produced from E. coli.
- LHRH is modified by substitution of sixth amino acid glycine by leucine, and linked to E. coli heat-labile enterotoxin as carrier.
- Recombinant LHRH fusion protein is purified to homogeneity from bacteria and characterized.
- Recombinant protein LHRH(6leu)-LTB is immunoreactive with anti-LHRH monoclonal antibodies.
- It can be a potential vaccine candidate for the management of hormone-dependent cancers in humans.

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.