02 BOOK OF ABSTRACTS .indd

Tumor VEGF modulates host proteolytic activity during
ovarian cancer progression
D. Belotti 1 , C. Calcagno 1 , A. Garofalo 1 , L. Manenti 1 , M. Broggini 2 ,
G. Taraboletti 1 and R. Giavazzi 1
1
Laboratory of Biology and Treatment of Metastasis, and 2 Laboratory of Molecular
Pharmacology, Department of Oncology, Mario Negri Institute for Pharmacological
Research, 24125 Bergamo, Italy
A mutual regulation between VEGF and MMPs has been recently reported. VEGF
stimulates MMP production, and, in turn, MMPs regulate the bioavailability of VEGF.
We have previously reported that MMPs are involved in the release of VEGF and
in ascites formation in ovarian carcinoma. To further investigate the functional
interplay between VEGF and MMPs in ovarian carcinoma progression, we have
established a model of human ovarian carcinoma cells overexpressing VEGF and
disseminating in the peritoneal cavity of nude mice. Xenograft variants derived
from the A2780 human ovarian carcinoma (1A9), stably expressing VEGF 121
in sense
(1A9-VS-1) and antisense orientation (1A9-VAS-3) were generated and the invasive
and metastatic potential of tumor cells producing different levels of VEGF was
evaluated. 1A9-VS-1 and 1A9-VAS-3 disseminated in the peritoneal cavity of nude
mice, but only 1A9-VS-1, the VEGF 121
overexpressing tumor variant, produced ascites.
Significant levels of soluble VEGF were detected in plasma of mice bearing 1A9-VS-
1.
p2
Supported by the European Union FP6, LSHC-CT-2003-503297.
An augmentation in murine MMP9 expression was observed in tumors of mice
transplanted with 1A9-VS-1 compared to mice bearing 1A9-VAS-3 tumors, indicating
that VEGF produced by tumor cells stimulates host expression of the matrixdegrading
enzyme. Moreover, we found that tumor VEGF modulated the proteolytic
activity of stromal cells not only within the tumor but also in distant organs of
tumor-bearing-mice. In particular the organs could be ordered into three typologies
in relation to their proteolytic activity: 1) organs that presented a general increase
in gelatinases in tumor-bearing mice compared to healthy mice, but independently
from VEGF production (spleen, lung, liver, and uterus); 2) organs that showed no
alteration in the levels of gelatinases (kidney and pancreas); and 3) organs that
presented a VEGF-dependent increase in murine MMP-9 (ovaries). Notably, the
levels of proMMP-9 in ovaries correlated with the plasma levels of VEGF.
In vitro VEGF did not induce autocrine changes in tumor cell migration and
invasiveness. On the contrary, tumor derived VEGF modulated invasion and MMP2
and MMP9 expression in endothelial cells. The use of specific inhibitors of VEGF
receptor demonstrated the specificity of the effects.
Altogether these findings point to a complex cross-talk between VEGF and MMPs in
determining ovarian tumor progression.
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