Design, synthesis, and characterization of the antitumor activity of novel ceramide analogues.
A deficiency in apoptosis is one of the key events in the proliferation and resistance of malignant cells to antitumor agents; for these reasons, the search for apoptosis-inducing drugs represents a valuable approach for the development of novel anticancer therapies. In this study we report the first example of conformationally restrained analogues of ceramide (compounds 1-4), where the polar portion of the molecule has been replaced by a thiouracil (1, 3) or uracil (2, 4) ring. The evaluation of their biologic activity on CCRF-CEM human leukemia cells demonstrated that the most active was compound 1 followed by compound 2 (mean 50% inhibition of cell proliferation [IC(50)] 1.7 and 7.9 microM, respectively), while compounds 3 and 4 were inactive, as were uracil, thiouracil, and 5,6-dimethyluracil, the pyrimidine moieties of compounds 1-4. For comparison, the IC(50) of the reference substance, the cell-permeable C2-ceramide, was 31.6 microM. Compounds 1 and 2 and C2-ceramide were able to trigger apoptosis, as shown by the occurrence of DNA and nuclear fragmentation, and to release cytochrome c from treated cells. The treatment of female CD-1 nu/nu athymic mice bearing a WiDr human colon xenograft with the most active compound 1 at 2, 10, 50, and 200 mg/kg ip daily for 10 days resulted in an antitumor effect that was equivalent at 50 mg/kg or superior (200 mg/kg) to that of cyclophosphamide, 20 mg/kg ip daily, delivered on the same schedule, with markedly lower systemic toxicity. In conclusion, the present study demonstrates that the new ceramide analogues 1 and 2 are characterized by in vitro and in vivo antitumor activity and low toxicity.
Macchia
M
M
Department of Pharmaceutical Sciences, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy. mmacchia@farm.unipi.it
Barontini
S
S
Bertini
S
S
Di Bussolo
V
V
Fogli
S
S
Giovannetti
E
E
Grossi
E
E
Minutolo
F
F
Danesi
R
R
D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002518:Ceramides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D004354:Drug Screening Assays, Antitumor; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D015151:Immunoblotting; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008819:Mice, Nude; D013329:Structure-Activity Relationship; D013889:Thiouracil / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D014498:Uracil / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
D000970:Antineoplastic Agents; D002518:Ceramides; D003574:Cytochrome c Group; D014498:Uracil; D013889:Thiouracil; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases