Inhibition of Src impairs the growth of met-addicted gastric tumors.
OBJECTIVE
We examined whether inhibition of Src tyrosine kinase, a downstream effector of the MET oncogene, can hinder the malignant properties of gastric tumors dependent on Met for growth and survival.


METHODS
Sensitivity to Src inhibition was determined in vitro by measuring clonogenic survival (anchorage-independent growth) and in vivo by establishing xenograft models. Four "Met-addicted" gastric carcinoma cell lines (GTL16, MKN45, HS746T, and SNU5) and three Met-independent gastric carcinoma cell lines (KATO III, AGS, and NCI-N87) were treated with the Src inhibitor saracatinib (AZD0530). In GTL16 and KATO III, Src neutralization was also achieved by dasatinib and RNA interference. The biochemical and transcriptional consequences of Src inhibition were explored using anti-phosphoprotein antibodies and oligonucleotide microarrays.


RESULTS
Inhibition of Src in Met-addicted gastric carcinoma cell lines (a) decreased the phosphorylation/activation levels of signaling intermediates involved in cell proliferation and protection from apoptosis and down-modulated the expression of several cell cycle regulators; (b) reduced anchorage-independent growth; (c) enhanced impairment of cell viability produced by Met inhibition; and (d) delayed tumorigenesis in xenotransplantation models. Immunohistochemical analysis of tumor xenograft tissues following systemic treatment with saracatinib showed a reduction of tumor cell proliferation index, increased apoptosis, and diminished phospho-focal adhesion kinase and phospho-paxillin staining. Tumor stroma parameters such as angiogenesis or inflammatory infiltration were unaffected. In clonogenic survival assays, gastric carcinoma cells without addiction to Met were less sensitive than Met-addicted cells to Src inhibition.


CONCLUSIONS
Src is as a key downstream transducer of Met-driven tumor growth. Targeting Src might provide therapeutic benefit in Met-addicted tumors.
Bertotti
Andrea
A
Division of Molecular Oncology and Laboratory of Functional Genomics, The Oncogenomics Center, Institute for Cancer Research and Treatment, University of Torino Medical School, Strada Provinciale 142, Candiolo, Turin, Italy.
Bracco
Cecilia
C
Girolami
Flavia
F
Torti
Davide
D
Gastaldi
Stefania
S
Galimi
Francesco
F
Medico
Enzo
E
Elvin
Paul
P
Comoglio
Paolo M
PM
Trusolino
Livio
L
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics
D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D019859:Proto-Oncogene Proteins c-met; D019061:src-Family Kinases