Abstract
Purpose: :
Vascular Endothelial Growth Factor (VEGF) is an important cytokine in the development and formation of new blood vessels and in tumorigenesis. Bevacizumab, a monoclonal antibody that blocks VEGF-A, is used to treat colon and lung cancer. The purpose of this project is to investigate the production of angiogenic factors by uveal melanoma cell lines and to determine the effects of Bevacizumab therapy on proliferation, migration, and invasion.
Methods: :
For the in vitro experiments, 92.1, OCM-1, and UW-1 uveal melanoma cell lines were used. Invasion and migration assays were performed (Cytoselect, Cell Biolabs). The proliferation assay was performed using an MTT-based toxicology kit (Sigma). Assays were performed using 100ul/ml of Bevacizumab (Avastin, Roche) for 24 hours. The production of Angiogenin, ANG-2, EGF, bFGF, HB-EGF, HGF, Leptin, PDGF-BB, PIGF, and VEGF by the three cell lines were quantified using the Quantibody Human Angiogenesis Array 1 (Raybiotech, Inc). Immunostaining for VEGFR-2 was performed using the automated Ventana Benchmark System with a monoclonal antibody against VEGFR-2 (Abcam).
Results: :
100ul/ml of Bevacizumab resulted in inhibition of proliferation in all three cell lines (p<0.05). There was a reduction in the average number of migrating and invading cells once exposed to Bevacizumab at 100ug/ml but this decrease was significant (p <0.05) only in the 92.1 and OCM-1 cell line invasion. Treatment with Bevacizumab eliminated the secretion of VEGF and Angiogenin production was reduced in all cell lines. PIGF was reduced in the two cell lines (92.1 and UW-1) in which it was detected. EGF and HB-EGF were reduced in the 92.1 and UW-1 cell lines. In the OCM-1 cell line, EGF production and HB-EGF production had a slight increase. None of the other cytokines were produced in detectable quantities. All three cell lines showed positive cytoplasmic immnostaining for VEGFR-2.
Conclusions: :
Bevacizumab abolished the production of VEGF in three uveal melanoma cell lines and reduced production of other important angiogenic cytokines, such as Angiogenin, in culture. Bevacizumab also reduced the ability of cell lines to proliferate, migrate, and invade at a concentration of 100ul/mg. VEGFR-2 was expressed, thus the endogenous production of this cytokine may operate in an autocrine or paracrine loop. More studies to investigate the inhibitory effects in vivo are warranted.
Keywords: tumors • melanoma • choroid