title: Targeted cytotoxic bombesin analog AN-215 effectively inhibits experimental human breast cancers with a low induction of multi-drug resistance proteins.
abstract: The cytotoxic analog of bombesin (BN)/gastrin releasing peptide (GRP) AN-215 consisting of 2-pyrrolinodoxorubicin (AN-201), a superactive derivative of doxorubicin linked to a bombesin analog carrier, displays a high affinity to BN/GRP receptors and can be targeted to tumors that express these receptors. We evaluated the antitumor effect and the toxicity of AN-215 in 5 human breast cancer cell lines xenografted into nude mice. In addition, we measured the mRNA expression of multi drug resistance protein 1 (MDR-1), multi drug resistance related protein 1 (MRP-1) and breast cancer resistance protein (BCRP) by real-time PCR analysis after treatment with AN-215. All five cell lines expressed BN/GRP receptors, and AN-215 significantly (P < 0.05) inhibited tumor growth in all models, while its cytotoxic radical AN-201 had no significant effect in four models. In MX-1 tumors, AN-201 had a significantly weaker antitumor effect than AN-215. The effect of AN-215 was nullified by a blockade of BN/GRP receptors with a bombesin antagonist. Low or no induction of MDR-1, MRP-1 and BCRP occurred after treatment with AN-215. In conclusion, targeted chemotherapy with the cytotoxic BN/GRP analog AN-215 strongly inhibits breast cancers that express BN/GRP receptors and might provide a new treatment modality for mammary carcinoma.
authors.affiliation: Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center and Section of Experimental Medicine, Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA.
authors.forename: Jörg B
authors.initials: JB
authors.lastname: Engel
authors.forename: Andrew V
authors.initials: AV
authors.lastname: Schally
authors.forename: Gabor
authors.initials: G
authors.lastname: Halmos
authors.forename: Benjamin
authors.initials: B
authors.lastname: Baker
authors.forename: Attila
authors.initials: A
authors.lastname: Nagy
authors.forename: Gunhild
authors.initials: G
authors.lastname: Keller
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001839:Bombesin / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000737:chemistry / Q000188:drug therapy* / Q000378:metabolism; D004317:Doxorubicin / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D018432:Drug Resistance, Multiple; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D018004:Receptors, Bombesin / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism; D015854:Up-Regulation; D023041:Xenograft Model Antitumor Assays
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D001839:Bombesin; D004317:Doxorubicin; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D018004:Receptors, Bombesin; C116614:ABCG2 protein, human; C416531:AN 215; C421109:multidrug resistance-associated protein 1