Dual inhibition of Raf and VEGFR2 reduces growth and vascularization of hepatocellular carcinoma in an experimental model.
OBJECTIVE
Activation of the mitogen-activated protein kinase-extracellular-signal-regulated kinase (ERK) pathways plays an important role in the progression of hepatocellular carcinoma (HCC). Importantly, Raf kinases are principal effectors within this oncogenic signaling cascade. We hypothesized that concomitant inhibition of Raf and vascular endothelial growth factor receptor 2 (VEGFR2) will affect tumor growth and angiogenesis of HCC.


METHODS
Human HCC cell lines, endothelial cells (EC), and vascular smooth muscle cells (VSMC) were used. For blocking Raf kinase and VEGFR2, the small molecule inhibitor NVP-AAL881 (Novartis, USA) was used. Activation of signaling intermediates was assessed by Western blotting, and changes in cell motility were evaluated in migration assays. Effects of NVP-AAL881 on HCC growth were determined in a subcutaneous tumor model.


RESULTS
NVP-AAL881 disrupted activation of ERK and STAT3 in HCC cells and reduced cancer cell motility. In addition, the migration of ECs and VSMC was also significantly impaired. In ECs, HCC-conditioned media-induced activation of STAT3 was diminished by NVP-AAL881 treatment. In vivo, NVP-AAL881 significantly reduced tumor growth, CD31-vessel area, and numbers of BrdU-positive proliferating tumor cells.


CONCLUSIONS
Combined inhibition of Raf and VEGFR2 disrupts oncogenic signaling and efficiently reduces tumor growth and vascularization of HCC. Hence, this strategy could prove valuable for therapy of HCC.
Lang
Sven Arke
SA
Department of Surgery, University of Regensburg Medical Center, Regensburg, Germany. sven.lang@klinik.uni-regensburg.de
Brecht
Isabel
I
Moser
Christian
C
Obed
Aiman
A
Batt
David
D
Schlitt
Hans Juergen
HJ
Geissler
Edward Kenneth
EK
Stoeltzing
Oliver
O
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D008114:Liver Neoplasms, Experimental / Q000098:blood supply* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000473:pathology; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000473:pathology*; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors*; D048490:raf Kinases / Q000037:antagonists & inhibitors*
C514876:AAL 881; D000970:Antineoplastic Agents; D007546:Isoquinolines; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D040301:Vascular Endothelial Growth Factor Receptor-2; D048490:raf Kinases