title: Triple negative breast cancers express receptors for LHRH and are potential therapeutic targets for cytotoxic LHRH-analogs, AEZS 108 and AEZS 125.
abstract: BACKGROUND
  Triple negative breast cancer (TNBC) is a distinct subtype of breast cancer burdened with a dismal prognosis due to the lack of effective therapeutic agents. Receptors for LHRH (luteinizing hormone-releasing hormone) can be successfully targeted with AEZS-108 [AN-152], an analog of LHRH conjugated to doxorubicin. Our study evaluates the presence of this target LHRH receptor in human specimens of TNBC and investigates the efficacy and toxicity of AEZS-108 in vivo. We also studied in vitro activity of AEZS-125, a new LHRH analog conjugated with the highly potent natural compound, Disorazol Z.
  
  
  METHODS
  69 human surgical specimens of TNBC were investigated for LHRH-R expression by immunohistochemistry. Expression of LHRH-R in two TNBC cell lines was evaluated by real time RT-PCR. Cytotoxicity of AEZS-125 was evaluated by Cell Titer Blue cytoxicity assay. LHRH- receptor expression was silenced with an siRNA in both cell lines. For the in vivo experiments an athymic nude mice model xenotransplanted with the cell lines, MDA-MB-231 and HCC 1806, was used. The animals were randomised to three groups receiving solvent only (d 1, 7, 14, i.v.) for control, AEZS-108 (d 1, 7, 14, i.v.) or doxorubicin at an equimolar dose (d 1, 7, 14, i.v.).
  
  
  RESULTS
  In human clinical specimens of TNBC, expression of the LHRH-receptor was present in 49% (n = 69).HCC 1806 and MDA-MB-231 TNBC cells expressed mRNA for the LHRH-receptor. Silencing of the LHRH-receptor significantly decreased the cytotoxic effect of AEZS-108. MDA-MB-231 and HCC 1806 tumors xenografted into nude mice were significantly inhibited by treatment with AEZS-108; doxorubicin at equimolar doses was ineffective.As compared to AEZS 108, the Disorazol Z - LHRH conjugate, AEZS-125, demonstrated an increased cytotoxicity in vitro in HCC 1806 and MDA-MB-231 TNBC; this was diminished by receptor blockade with synthetic LHRH agonist (triptorelin) pretreatment.
  
  
  CONCLUSIONS
  The current study confirms that LHRH-receptors are expressed by a significant proportion of TNBC and can be successfully used as homing sites for cytotoxic analogs of LHRH, such as AEZS-108 and AEZS-125.
authors.forename: Stephan
authors.initials: S
authors.lastname: Seitz
authors.forename: Stefan
authors.initials: S
authors.lastname: Buchholz
authors.forename: Andrew Victor
authors.initials: AV
authors.lastname: Schally
authors.forename: Florian
authors.initials: F
authors.lastname: Weber
authors.forename: Monika
authors.initials: M
authors.lastname: Klinkhammer-Schalke
authors.forename: Elisabeth C
authors.initials: EC
authors.lastname: Inwald
authors.forename: Roberto
authors.initials: R
authors.lastname: Perez
authors.forename: Ferenc G
authors.initials: FG
authors.lastname: Rick
authors.forename: Luca
authors.initials: L
authors.lastname: Szalontay
authors.forename: Florian
authors.initials: F
authors.lastname: Hohla
authors.forename: Sabine
authors.initials: S
authors.lastname: Segerer
authors.forename: Chui Wai
authors.initials: CW
authors.lastname: Kwok
authors.forename: Olaf
authors.initials: O
authors.lastname: Ortmann
authors.affiliation: Depertment of Obsteterics and Gynecology, Medical University of Gießen, 35392 Gießen, Germany. joergbengel@hotmail.com.
authors.forename: Jörg Bernhard
authors.initials: JB
authors.lastname: Engel
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004317:Doxorubicin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010080:Oxazoles / Q000008:administration & dosage* / Q000494:pharmacology; D011966:Receptors, LHRH / Q000235:genetics / Q000378:metabolism*; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: C000600168:AEZS-125; D000970:Antineoplastic Agents; D010080:Oxazoles; D011966:Receptors, LHRH; C080883:LHRH, lysine(6)-doxorubicin; D007987:Gonadotropin-Releasing Hormone; D004317:Doxorubicin