Inhibition of Src phosphorylation alters metastatic potential of osteosarcoma in vitro but not in vivo.
OBJECTIVE
Pulmonary metastasis remains the major cause of mortality in osteosarcoma. Src tyrosine kinase is a key player involved in metastatic pathways in multiple human cancers. c-Src has been shown to be expressed and phosphorylated in osteosarcoma cell lines and inhibiting Src phosphorylation in these cells causes inhibition of the metastatic phenotype in vitro. We studied the effect of inhibition of Src phosphorylation in preventing the growth and development of pulmonary metastases in osteosarcoma.


METHODS
Dasatinib, a dual Src-Abl kinase inhibitor, was used to study the effect of Src kinase inhibition on proliferation, adhesion, and invasion of osteosarcoma cell lines in vitro and in preventing the development of pulmonary metastases in a spontaneously metastatic mouse model.


RESULTS
In vitro, phosphorylation of Src and its downstream signaling molecules such as focal adhesion kinase, Crk-associated substrate, and c-Jun was inhibited at nanomolar concentrations of dasatinib. Dasatinib was not cytotoxic against the osteosarcoma cells with the IC(50) ranging from 10 to 20 micromol/L but effectively inhibited the adhesion and migration of osteosarcoma cells at 10 to 100 nmol/L. However, in vivo, dasatinib did not inhibit the development of pulmonary metastases despite complete inhibition of Src phosphorylation in the primary tumors. No effect was seen in the primary tumor growth and the degree of apoptosis.


CONCLUSIONS
These results suggest that Src kinase activation might not be the primary pathway involved in the development of pulmonary metastases in osteosarcoma.
Hingorani
Pooja
P
Department of Pediatric Hematology Oncology, Phoenix Children's Hospital, Phoenix, AZ 85016, USA. pooja_gidwani@yahoo.com
Zhang
Wendong
W
Gorlick
Richard
R
Kolb
E Anders
EA
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D000069439:Dasatinib; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000556:secondary; D051379:Mice; D016513:Mice, SCID; D012516:Osteosarcoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D011743:Pyrimidines / Q000494:pharmacology* / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects; D013844:Thiazoles / Q000494:pharmacology* / Q000627:therapeutic use; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays / Q000379:methods; D019061:src-Family Kinases / Q000378:metabolism*
D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D013844:Thiazoles; D019061:src-Family Kinases; D000069439:Dasatinib