Effect of Src kinase inhibition on metastasis and tumor angiogenesis in human pancreatic cancer

Tumor angiogenesis is a process that requires migration,
proliferation, and differentiation of endothelial cells. We
hypothesized that decrease in pancreatic tumor growth due to
inhibition of src activity is associated with the inability of src
kinase to trigger a network of such signaling processes, which
finally leads to endothelial cell death and dormancy of
angiogenesis. The therapeutic efficacy of Src kinase inhibitor
AZM475271 was tested in nude mice orthotopically xenografted with
L3.6pl pancreatic carcinoma cells. No liver metastases and
peritoneal carcinosis were detected and a significant effect on the
average pancreatic tumor burden was observed following treatment
with AZM475271, which in turn correlated with a decrease in cell
proliferation and an increase in apoptotic endothelial cells.
AZM475271 was shown to significantly inhibit migration of human
umbilical vein endothelial cells in an in vitro Boyden Chamber cell
migration assay. In a rat aortic ring assay we could demonstrate as
well inhibition of endothelial cell migration and sprouting
following therapy with Src kinase inhibitor at similar doses.
Furthermore, we could show reduced proliferation of HUVECs
determined with the TACS MTT Cell Viability Assay Kit. The blockade
of Src kinase significantly reduced the level of VEGF in L3.6pl
medium, the effect which was found also in the cell culture
supernate from HUVECs. Inhibition of Src kinase by AZM475271 also
showed prevention of survival signalling from VEGF and EGF
receptors. Treatment with AZM475271 resulted in VEGF – dependent
inhibition of tyrosine phosphorylation of FAK. HUVECs were also
examined using propidium iodide staining for cell cycle analysis by
FACS. Inhibition of src kinase promoted HUVEC apoptosis in a
dose-dependent manner. Taken together, our results suggest that the
Src kinase inhibitor AZM475271, in addition to its effects on tumor
cells, suppresses tumor growth and metastasis in vitro and in vivo
potentially also by anti-angiogenic mechanisms.