Iron containing anti-tumoral agents: unexpected apoptosis-inducing activity of a ferrocene amino acid derivative.
OBJECTIVE
Due to the severe problems accompanied with multiple drug resistance (MDR), agents that can induce apoptosis independently of death-suppressing proteins are required. Here, we show that the ferrocene derivative HUNI 068 is active against cancer cells and overcomes different mechanisms of multiple drug resistance (MDR).


METHODS
Proliferation inhibition was determined by using a CASY(®)CellCounter. DNA fragmentation assay and annexin-V/PI binding assays measured apoptosis, and necrosis was excluded by LDH-release assay. Drug-resistant cell lines were generated to test the ability to overcome MDR. By real-time PCR, alterations in gene expression of treated cells were analyzed. The apoptosis pathway was investigated by immunoblotting and measurement of mitochondrial membrane permeability transition.


RESULTS
HUNI 068 leads to proliferation inhibition and apoptosis mediation, but only minimal necrosis induction. Healthy leukocytes seem to be less affected than cancer cells. The compound overcomes drug resistance to vincristine and daunorubicin. Independence of p-glycoprotein and Bcl-2 overexpression is probable, and upregulation of the anti-Bcl-2 protein harakiri was seen. Combined treatment with vincristine leads to synergistic effects. In different primary tumor cells, HUNI 068 achieved acceptable effects where tolerance to some conventional drugs was shown. Induction of apoptosis is FADD-independent, but associated with a reduced mitochondrial membrane potential and activation of caspase-9, indicating the intrinsic apoptosis pathway via mitochondria.


CONCLUSIONS
HUNI 068 is a promising new compound with activity even against MDR tumor cells. Further investigations into the class of ferrocene-derived agents might reveal compounds with improved activity for a more specific and safe anti-cancer therapy.
Kater
Benjamin
B
Department of Pediatric Oncology/Hematology, University Medical Center Charité, Campus Virchow, Augustenburger Platz 1, 13353 Berlin, Germany. benjamin.kater@charite.de
Hunold
Andrea
A
Schmalz
Hans-G
HG
Kater
Lisa
L
Bonitzki
Birgit
B
Jesse
Patrick
P
Prokop
Aram
A
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D005296:Ferrous Compounds / Q000494:pharmacology*; D006801:Humans; D007938:Leukemia / Q000188:drug therapy; D007962:Leukocytes / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D000075163:Metallocenes; D013386:Succinates / Q000494:pharmacology*; D014750:Vincristine / Q000494:pharmacology
D000970:Antineoplastic Agents; D005296:Ferrous Compounds; C558245:HUNI 068; D000075163:Metallocenes; D013386:Succinates; D014750:Vincristine; D053453:Caspase 9; C004998:ferrocene