Src family kinase activity is required for signal tranducer and activator of transcription 3 and focal adhesion kinase phosphorylation and vascular endothelial growth factor signaling in vivo and for anchorage-dependent and -independent growth of human tumor cells.
The Src family kinases (SFKs) Src and Yes are believed to play critical roles in tumor growth, angiogenesis, invasion, and dissemination. Using a panel of highly selective and structurally diverse Src inhibitors, we found that phosphorylation of signal transducer and activator of transcription 3 [STAT3 (Y705)] and focal adhesion kinase [FAK (Y861)] was SFK dependent in cultured human colon, breast, lung, and ovarian tumor cells. These findings were reproduced in vivo in target modulation studies using tumors derived from fibroblasts overexpressing activated Src. Additionally, treatment of mice with multiple Src inhibitors resulted in inhibition of phosphorylation of FAK (Y861) and of a putative Src autophosphorylation epitope (Y419) in HT-29 human colon tumor xenografts. Next we pharmacologically examined the requirement for SFKs in asynchronous proliferation of human tumor cells. At concentrations sufficient to selectively inhibit Src, structurally diverse Src inhibitors inhibited growth of cultured human colon, breast, and lung cells on plastic under low serum conditions. In addition, these compounds inhibited anchorage-independent growth of HT-29 human colon tumor cells in soft agar. The role of SFK activity in vascular endothelial growth factor signaling was also evaluated. Inhibition of SFK signaling using structurally distinct Src inhibitors resulted in complete inhibition of vascular endothelial growth factor-dependent vascular permeability in vivo. These data demonstrate that STAT3 (Y705) and FAK (Y861) phosphoepitopes are SFK-dependent in tumor cells and reveal a requirement for SFK function in tumor cell proliferation and vascular permeability.
Laird
A Douglas
AD
Preclinical Research and Exploratory Development, SUGEN, Inc., South San Francisco, California 94080, USA. Douglas-Laird@sugen.com
Li
Guangmin
G
Moss
Katherine G
KG
Blake
Robert A
RA
Broome
Martin A
MA
Cherrington
Julie M
JM
Mendel
Dirk B
DB
D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D042461:Vascular Endothelial Growth Factor A; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; C496051:Ptk2 protein, mouse; D019061:src-Family Kinases