Benzyl isothiocyanate suppresses pancreatic tumor angiogenesis and invasion by inhibiting HIF-α/VEGF/Rho-GTPases: pivotal role of STAT-3.
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.
Department of Biomedical Sciences and Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas, United States of America.
Srinivas Reddy
SR
Boreddy
Ravi P
RP
Sahu
Sanjay K
SK
Srivastava
D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D017879:Isothiocyanates / Q000494:pharmacology* / Q000627:therapeutic use; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009361:Neoplasm Invasiveness; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D010190:Pancreatic Neoplasms / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051381:Rats; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017879:Isothiocyanates; D050796:STAT3 Transcription Factor; D042461:Vascular Endothelial Growth Factor A; C031403:benzyl isothiocyanate; D040301:Vascular Endothelial Growth Factor Receptor-2; D020778:Matrix Metalloproteinase 2; D020741:rho GTP-Binding Proteins