In vitro targeting of a cytotoxic analog of luteinizing hormone-releasing hormone AN-207 to ES-2 human ovarian cancer cells as demonstrated by microsatellite analyses.
Targeting of cytotoxic agents represents a modern approach to the treatment of various cancers, that improves the efficacy and reduces peripheral toxicity. Recently we developed a powerful cytotoxic analog of luteinizing hormone-releasing hormone (LHRH), AN-207, designed to be targeted to tumors that express LHRH receptors. This analog consists of the superactive derivative of doxorubicin (DOX), 2-pyrrolino-DOX (AN-201), linked to [D-Lys6]LHRH carrier. In the present study we investigated the cytocidal effects of AN-207 and AN-201 on the LHRH receptor-positive ES-2 ovarian cancer cells. The targeting of AN-207 to ES-2 cells in the presence of LHRH receptor-negative UCI-107 ovarian cancer cells was also evaluated by semi-quantitative polymerase chain reaction (PCR) amplification of microsatellite markers. Ligand competition assays showed a single class of high-affinity and low-capacity binding sites in ES-2 cells with a mean dissociation constant (KD) of 3.93 +/- 0.1 nM and a mean maximal binding capacity (Bmax) of 271 +/- 26.1 fmol/mg membrane protein. Kinetic assays indicated that AN-207 caused cell death in a concentration- and time-dependent manner in ES-2 cells, but not in UCI-107 cells, while the kinetics of cytotoxic effects of AN-201 were similar in both cell lines. To investigate targeting, ES-2 cells were co-cultured with UCI-107 cells, treated with 10 nM AN-207 or AN-201 for different times and then cultured for 48 h in the absence of cytotoxic agents. Genomic DNA was extracted for microsatellite analyses using different markers. Semi-quantitative analyses of the intensity of the alleles that correspond to each cell line indicated that AN-207 was selectively targeted to ES-2 cells, while AN-201 showed no selectivity for either cell line. These results extend our previous findings that AN-207 can be targeted to ovarian cancers and other tumors that express receptors for LHRH. Cytotoxic analogs of LHRH, such as AN-207, should be considered for treatment of LHRH receptor-positive tumors.
Arencibia
J M
JM
Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center and Tulane University School of Medicine, New Orleans, LA 70112-1262, USA.
Schally
A V
AV
Halmos
G
G
Nagy
A
A
Kiaris
H
H
D000970:Antineoplastic Agents / Q000494:pharmacology*; D018920:Coculture Techniques; D004317:Doxorubicin / Q000031:analogs & derivatives / Q000494:pharmacology*; D016503:Drug Delivery Systems; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000494:pharmacology*; D006801:Humans; D018895:Microsatellite Repeats; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D011966:Receptors, LHRH / Q000235:genetics / Q000378:metabolism*; D018675:Toxicity Tests; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D011966:Receptors, LHRH; C104648:AN 207; D007987:Gonadotropin-Releasing Hormone; D004317:Doxorubicin