Effects of polyamine depletion by alpha-difluoromethylornithine on in vitro and in vivo biological properties of 4T1 murine mammary cancer cells.
Increased polyamine synthesis has been associated with proliferation and progression of breast cancer, and thus, is a potential target for anticancer therapy. Polyamine depletion by alpha-difluoromethylornithine (DFMO) has been shown to decrease pulmonary and bone metastasis from human breast cancer cell xenografts. Following these observations, this study was designed to test the effects of DFMO on in vitro and in vivo features of the highly invasive and metastatic 4T1 murine mammary cancer cells. DFMO inhibited proliferation, caused G1-S arrest, and suppressed in vitro invasiveness of 4T1 cells. In contrast to our previous findings with MDA-MB-435 cells, DFMO did not affect the activation of signal transducers and activator of transcription 3, c-Jun N-terminal kinase, and extracellular signal-regulated kinase, but decreased phosphorylation of p38. DFMO did not alter the expression of Twist. DFMO delayed the orthotopic growth of 4T1 xenografts in association with suppressed putrescine and spermidine levels but increased levels of spermine. DFMO did not affect pulmonary metastasis when primary tumors of control and DFMO-treated mice were matched for size. Interestingly, DFMO reduced Ki-67 expression only in the primary tumors but did not affect its expression in the metastatic tumors in the lung. Cleaved caspase-3 expression was not affected by DFMO in either the primary tumors or the pulmonary metastasis. In summary, DFMO treatment markedly inhibited in vitro proliferation and invasiveness of 4T1 cells and retarded the growth of orthotopic xenografts in mice. The failure of DFMO to inhibit pulmonary metastasis in this system appears to be due, at least in part, to its lack of antiproliferative effect at the metastatic sites.
Jun
John Yoonkeun
JY
Department of Medicine, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Griffith
James W
JW
Bruggeman
Richard
R
Washington
Sharlene
S
Demers
Laurence M
LM
Verderame
Michael F
MF
Manni
Andrea
A
D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D000518:Eflornithine / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D066298:In Vitro Techniques; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism; D015674:Mammary Neoplasms, Animal / Q000378:metabolism*; D051379:Mice; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D010766:Phosphorylation; D011073:Polyamines / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D011073:Polyamines; D050796:STAT3 Transcription Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D000518:Eflornithine