Artikel
A Smac Mimetic Blocks TRAIL-Induced Invasion and Metastasis of Cholangiocarcinoma Cells by Inhibition of NF-κB
Suche in Medline nach
Autoren
Veröffentlicht: | 20. Mai 2011 |
---|
Gliederung
Text
Introduction: Cholangiocarcinoma (CCA) remains a devastating disease with limited therapeutic options. CCA cells paradoxically express TRAIL, an apoptosis-inducing ligand which, failing to kill CCA cells, instead promotes their tumorigenicity, especially NF-κB-mediated metastasis. Smac mimetics are new proapoptotic cancer therapeutic agents, which degrade inhibitor of apoptosis proteins (IAPs). We here examined the effects of the Smac mimetic JP1584 in CCA cells in vitro and in vivo.
Materials and methods: We employed human (KMCH-1, TFK-1) and rat (BDEneu) CCA cells as well as an orthotopic, syngeneic, rodent in vivo model of CCA for this study.
Results: Despite JP1584-mediated degradation of the two IAPs cIAP-1 and cIAP-2, TRAIL failed to induce apoptosis in KMCH-1, TFK-1, and BDEneu cells, consistent with a downstream-block in apoptotic signaling. Because cIAP-1 and cIAP-2 also promote canonical NF-κB activation, the effect of JP1584 on this signaling pathway was examined. Treatment with JP1584 inhibited TRAIL-induced NF-κB activation and TRAIL-mediated upregulation of the proinvasive NF-κB target gene matrix metalloproteinase 7 (MMP7) as shown by immunoblot, immunocytochemistry, EMSA analysis and quantitative RT-PCR. JP1584 also reduced TRAIL-mediated CCA cell migration (cells/field; 8 ± 2 vs. 20 ± 2; p < 0.05) and invasion (RFU; 35 ± 2 vs. 55 ± 5; p < 0.05) in vitro. Consistent with these findings, siRNA-knockdown of MMP7 also inhibited TRAIL-induced CCA cell invasion. Finally, in a rat in vivo CCA model (BDEneu cells; Fischer 344 rats) JP1584-administration reduced extrahepatic metastases (11 % vs. 67 %; p < 0.05; Figure 1 [Fig. 1]) and MMP7 mRNA levels in tumors (relative ratio; 1 ± 0.3 vs. 4.5 ± 0.7; p < 0.05) suggesting higher cure rates after early surgical intervention in a future study (i.e., 70% rat liver resection including the tumor-bearing left lateral lobe).
Conclusion: While the Smac mimetic JP1584 does not sensitize to apoptosis, it reduces TRAIL-induced CCA cell metastatic behavior by inhibition of NF-κB. These data support the emerging concept that IAPs are prometastatic and represent targets for antimetastatic neoadjuvant and/or adjuvant therapies.