Department of Biomedical Sciences and Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas, United States of America.
PLoS One. 2011;6(10):e25799. doi: 10.1371/journal.pone.0025799. Epub 2011 Oct 10.
Our previous studies have shown that benzyl isothiocyanate (BITC) suppresses pancreatic tumor growth by inhibiting STAT-3; however, the exact mechanism of tumor growth suppression was not clear. Here we evaluated the effects and mechanism of BITC on pancreatic tumor angiogenesis. Our results reveal that BITC significantly inhibits neovasularization on rat aorta and Chicken-Chorioallantoic membrane. Furthermore, BITC blocks the migration and invasion of BxPC-3 and PanC-1 pancreatic cancer cells in a dose dependant manner. Moreover, secretion of VEGF and MMP-2 in normoxic and hypoxic BxPC-3 and PanC-1 cells was significantly suppressed by BITC. Both VEGF and MMP-2 play a critical role in angiogenesis and metastasis. Our results reveal that BITC significantly suppresses the phosphorylation of VEGFR-2 (Tyr-1175), and expression of HIF-α. Rho-GTPases, which are regulated by VEGF play a crucial role in pancreatic cancer progression. BITC treatment reduced the expression of RhoC whereas up-regulated the expression of tumor suppressor RhoB. STAT-3 over-expression or IL-6 treatment significantly induced HIF-1α and VEGF expression; however, BITC substantially suppressed STAT-3 as well as STAT-3-induced HIF-1α and VEGF expression. Finally, in vivo tumor growth and matrigel-plug assay show reduced tumor growth and substantial reduction of hemoglobin content in the matrigel plugs and tumors of mice treated orally with 12 µmol BITC, indicating reduced tumor angiogenesis. Immunoblotting of BITC treated tumors show reduced expression of STAT-3 phosphorylation (Tyr-705), HIF-α, VEGFR-2, VEGF, MMP-2, CD31 and RhoC. Taken together, our results suggest that BITC suppresses pancreatic tumor growth by inhibiting tumor angiogenesis through STAT-3-dependant pathway.
我们之前的研究表明，苄基异硫氰酸酯（BITC）通过抑制 STAT-3 抑制胰腺肿瘤生长；然而，肿瘤生长抑制的确切机制尚不清楚。在这里，我们评估了 BITC 对胰腺肿瘤血管生成的影响和机制。我们的结果表明，BITC 可显著抑制大鼠主动脉和鸡胚绒毛尿囊膜的新生血管形成。此外，BITC 以剂量依赖的方式阻断 BxPC-3 和 PanC-1 胰腺癌细胞的迁移和侵袭。此外，BITC 可显著抑制常氧和低氧条件下 BxPC-3 和 PanC-1 细胞中 VEGF 和 MMP-2 的分泌。VEGF 和 MMP-2 在血管生成和转移中起关键作用。我们的结果表明，BITC 可显著抑制 VEGFR-2（Tyr-1175）的磷酸化和 HIF-α的表达。VEGF 调节的 Rho-GTPases 在胰腺癌进展中起关键作用。BITC 处理降低了 RhoC 的表达，而上调了肿瘤抑制因子 RhoB 的表达。STAT-3 过表达或 IL-6 处理显著诱导 HIF-1α和 VEGF 的表达；然而，BITC 可显著抑制 STAT-3 以及 STAT-3 诱导的 HIF-1α和 VEGF 的表达。最后，体内肿瘤生长和 Matrigel plugs 实验显示，口服 12 μmol BITC 的小鼠的肿瘤生长和 Matrigel plugs 中的血红蛋白含量显著减少，表明肿瘤血管生成减少。BITC 处理的肿瘤的免疫印迹显示，STAT-3 磷酸化（Tyr-705）、HIF-α、VEGFR-2、VEGF、MMP-2、CD31 和 RhoC 的表达减少。综上所述，我们的研究结果表明，BITC 通过依赖 STAT-3 的途径抑制肿瘤血管生成来抑制胰腺肿瘤生长。
