title: Oxime bond-linked daunorubicin-GnRH-III bioconjugates exert antitumor activity in castration-resistant prostate cancer cells via the type I GnRH receptor.
abstract: It is well established that gonadotropin-releasing hormone receptors (GnRH-R) are expressed in different types of cancers, including castration-resistant prostate cancer (CRPC) and mediate the antiproliferative effect of GnRH analogs. Thus, these compounds are employed as targeting moieties to selectively deliver chemotherapeutic agents to cancer cells. GnRH-III, the decapeptide isolated from the sea lamprey brain, has lower potency than GnRH in stimulating gonadotropin secretion, but it exerts antiproliferative effects on many tumors expressing the GnRH-R. GnRH-III-based peptides are considered promising targeting moieties for the preparation of anticancer drug delivery systems. These studies were aimed at i) evaluating the antitumor activity of two cytotoxic oxime bond-linked daunorubicin (Dau)-GnRH-III derivative bioconjugates (Dau-GnRH-III, in which daunorubicin was coupled to the 8Lys in the native form of GnRH-III, and Dau-[4Lys(Ac)]-GnRH-III, in which daunorubicin was attached to the 8Lys of a GnRH-III derivative where 4Ser was replaced by an acetylated lysine) on CRPC cells; and ii) to elucidate the involvement of the classical GnRH-R (type I GnRH-R) in this antitumor activity. Our results demonstrated that both Dau-GnRH-III and Dau-[4Lys(Ac)]-GnRH-III were rapidly internalized into DU145 prostate cancer cells and exerted a significant cytostatic effect. Both bioconjugates increased the levels of the active form of caspase-3, indicating the involvement of apoptosis in their antitumor activity. The antiproliferative effect of both Dau-GnRH-III and Dau-[4Lys(Ac)]-GnRH-III was counteracted by the simultaneous treatment of the cells with Antide, an antagonist of the GnRH-R. Moreover, after silencing the type I GnRH-R the antitumor activity of both bioconjugates was completely abolished. These data demonstrate that in CRPC cells, daunorubicin-GnRH-III derivative bioconjugates: i) inhibit tumor cell proliferation, by triggering the apoptosis process; ii) exert their antitumor effect through the activation of the type I GnRH-R expressed on these cells. Cytotoxic-GnRH-III derivative may represent promising targeted chemotherapeutics for the treatment of CRPC patients.
authors.affiliation: Department of Pharmacological and Biomolecular Sciences, University of Milan, I-20133 Milan, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Montagnani Marelli
authors.affiliation: Department of Chemistry, University of Konstanz, D-78457 Konstanz, Germany.
authors.forename: Marilena
authors.initials: M
authors.lastname: Manea
authors.affiliation: Department of Pharmacological and Biomolecular Sciences, University of Milan, I-20133 Milan, Italy.
authors.forename: Roberta M
authors.initials: RM
authors.lastname: Moretti
authors.affiliation: Department of Pharmacological and Biomolecular Sciences, University of Milan, I-20133 Milan, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Marzagalli
authors.affiliation: Department of Pharmacological and Biomolecular Sciences, University of Milan, I-20133 Milan, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Limonta
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003630:Daunorubicin / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010091:Oximes / Q000737:chemistry / Q000494:pharmacology*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000473:pathology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D011966:Receptors, LHRH / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; C484844:GNRHR protein, human; D010091:Oximes; D011966:Receptors, LHRH; C448022:gonadotropin-releasing hormone-III; D007987:Gonadotropin-Releasing Hormone; D011761:Pyrrolidonecarboxylic Acid; D003630:Daunorubicin