lGnRH-III -- a promising candidate for anticancer drug development.

Lamprey gonadotropin-releasing hormone-III (lGnRH-III; Glp-His-Trp-Ser-His-Asp-Trp-Lys-Pro-Gly-NH2), a native isoform of human GnRH (GnRH-I), was initially isolated from the brain of the sea lamprey (Petromyzon marinus). It is a weak GnRH agonist, which exerts a direct antiproliferative effect on cancer cells and has an insignificant LH and FSH releasing potency in mammals. These features reveal the advantages of lGnRH-III and its derivatives for use in cancer therapy. Here we give an overview of various strategies to increase the antitumor activity of lGnRH-III, such as amino acid replacement, cyclization, dimerization and conjugation to polymers or to chemotherapeutic agents. In vitro and in vivo antitumor activity of lGnRH-III based compounds was demonstrated both on hormone dependent and independent tumors.