c-Met is a potentially new therapeutic target for treatment of human melanoma.
OBJECTIVE
c-Met is a receptor tyrosine kinase involved in cell growth, invasion, metastases, and angiogenesis. In this study, we investigated the role of c-Met in melanoma biology using a novel small-molecule tyrosine kinase inhibitor SU11274 and small interfering (si) RNA against the receptor.


METHODS
The effects of SU11274 and c-Met siRNA were studied on proliferation, apoptosis, differentiation, reactive oxygen species, and intracellular signaling. c-Met mutations were examined, and the expression of c-Met and activated c-Met was studied in nevi, primary, and metastatic melanoma.


RESULTS
c-Met was expressed in 6:7 melanoma cell lines by immunoblotting. SU11274 inhibited cell growth in all melanoma cell lines by 85% to 98% with an IC(50) between 1 and 2.5 mumol/L and caused apoptosis (12-58%) in five out of six cell lines. siRNA against c-Met inhibited proliferation of melanoma cells by 60%. This is the first study that shows that SU11274 and siRNA induced microphthalmia-associated transcription factor (MITF) and several other melanoma differentiation proteins and a morphologically differentiated phenotype. SU11274 also inhibited reactive oxygen species formation and phosphorylation of c-Met receptor, AKT and S-6 kinase by the hepatocyte growth factor. A new missense c-Met mutation N948S was identified in cell lines and R988C in tumor tissue in the juxtamembrane domain of c-Met. It was found that c-Met was expressed in 88% of melanomas and 15% of nevi, and that c-Met (pY1003) was activated in 21% of human melanomas.


CONCLUSIONS
These results support the role of c-Met in proliferation, apoptosis, differentiation, and tumor progression of melanoma. SU11274 could be used in the therapeutic inhibition of melanoma.
Puri
Neelu
N
Departments of Hematology/Oncology and Pathology, University of Chicago Medical Center, Chicago, Illinois 60607, USA.
Ahmed
Salman
S
Janamanchi
Varalakshmi
V
Tretiakova
Maria
M
Zumba
Osvaldo
O
Krausz
Thomas
T
Jagadeeswaran
Ramasamy
R
Salgia
Ravi
R
D000595:Amino Acid Sequence; D001483:Base Sequence; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D005455:Fluorescent Antibody Technique; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007211:Indoles / Q000494:pharmacology*; D008545:Melanoma / Q000188:drug therapy* / Q000378:metabolism; D051739:Microphthalmia-Associated Transcription Factor; D008969:Molecular Sequence Data; D009154:Mutation; D010879:Piperazines / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019859:Proto-Oncogene Proteins c-met / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology*; D014162:Transfection
C478479:((3Z)-N-(3-chlorophenyl)-3-((3,5-dimethyl-4-((4-methylpiperazin-1-yl)carbonyl)-1H-pyrrol-2-yl)methylene)-N-methyl-2-oxo-2,3-dihydro-1H-indole-5-sulfonamide); D007211:Indoles; D051739:Microphthalmia-Associated Transcription Factor; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D013449:Sulfonamides; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met