Angiogenesis inhibitor TNP-470 reduces human pancreatic cancer growth

In this study we investigated the effects of the angiogenesis inhibitor TNP -470 on human pancreatic cancer cells in vitro and in vivo. The action of T NP-470 on vascular endothelial growth factor (VEGF) was also assessed. In v itro human pancreatic cancer cells (MIAPaCa-2, AsPC-1, and Capan-1), and hu man umbilical vein endothelial cells (HUVEC) were exposed to increasing con centrations (1 pg/ml to 100 mug/ml) of TNP-470. Cell proliferation uas asse ssed after 3 days by cell count and MTT assay. In vivo, 5 x 10(6)' pancreat ic cancer cells were injected subcutaneously into nude mice. Four weeks lat er, 1 mm(3) fragments of the resulting tumors were implanted into the pancr eas of other mice. Animals received either TNP-470 (30 mg/kg every other da y) or vehicle subcutaneously for 14 weeks. The volume of the primary tumor and metastatic spread were determined at autopsy Concentrations of VEGF wer e determined in serum (VEGF(S)) and ascites (VEGF(A)) by enzyme-linked immu nosorbent assay. Microvessel density was analyzed by immunohistochemistry i n CD31-stained tumor sections. In vitro, proliferation and viability of the human pancreatic cancer cell lines were significantly inhibited at high co ncentrations of TNP-470 (> 1 mug/ml). In contrast, TNP -470 effectively dec reased the grow th of HUVEC at 100 pg/ml. In vivo, tumor volume and dissemi nation scores were significantly lower in all three pancreatic cancer cell lines. VEGF(S) and VEGF(A) were not different between treated groups. Treat ment with TNP-470 significantly reduced neoangiogenesis in tumors of all th ree human pancreatic cancer cell lines: MIAPaCa-2 = 74.8 +/- 7.8/0.74mm(2) vs. 24.8 +/- 3.7/0.74 mm(2); AsPC-1 = 65.3 +/- 5.0/0.74 mm(2) vs. 26.0 +/- 3.4/0.74 mm(2); and Capan-1 = 82.2 +/- 5.8/0.74 mm(2) vs. 26.9 +/- 2.5/0.74 mm(2) (P <0.001). However, survival was not statistically different betwee n groups. TNP-470 reduced tumor growth and metastatic spread of pancreatic cancer in vivo. This was probably due to the antiproliferative effect of th e agent on endothelial cells rather than to the direct inhibition of pancre atic cancer cell growth. TNP-470 activity was not associated with alteratio n of VEGF secretion.