Indirubin 3′-Oxime Inhibits Migration, Invasion, and Metastasis In Vivo in Mice Bearing Spontaneously Occurring Pancreatic Cancer via Blocking the RAF/ERK, AKT, and SAPK/JNK Pathways

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with high invasive and metastatic potential. We generated a spontaneous PDAC mouse model and examined the therapeutic potential of indirubin 3′-oxime (Indox) against PDAC bearing mouse in vivo. METHODS: Randomized 3-month-old LSL-Kras^G12D/+;Trp53^flox/+;Pdx-1-cre (KPC^flox) mice were intraperitoneally injected with 40 mg/kg Indox (n = 9) or a vehicle (n = 10) twice a week. At the end point, tumor status including proliferation, direct invasion, and distant metastasis was analyzed histopathologically. The inhibitory potentials of Indox for proliferation, migration/invasion, and the phosphorylation of target molecules were determined in KPC^flox-derived PDAC cells in vitro. RESULTS: Prolonged survival by Indox via intraperitoneal administration was observed in the KPC^flox mice. Indox inhibited tumor proliferation accompanied with low levels of nuclear phosphorylated cyclin-dependent kinase (p-CDK) and cyclin B1 in vivo. Furthermore, Indox inhibited the migration/invasive activities of PDAC via down-regulation of matrix metalloproteinase (MMP)-9 in vitro and in vivo. Antibody array and immunoblotting analysis revealed that Indox inhibited the phosphorylation of multiple molecules, including key upstream proteins of MMP-9 in RAF/extracellular signal-regulated kinase (ERK), AKT, and stress-activated protein kinase/c-Jun-N-terminal kinase (SAPK/JNK) pathways. CONCLUSION: Indox inhibited the proliferative, invasive, and metastatic potentials of PDAC in vitro and in vivo. Therefore, Indox could a therapeutic candidate for treating spontaneously occurring PDAC via blocking the RAF/ERK, AKT and SAPK/JNK pathways.