Efficient elimination of pancreatic cancer stem cells by hedgehog/GLI inhibitor GANT61 in combination with mTOR inhibition

Abstract

BackgroundPancreatic cancer is one of the most lethal malignancies. The innovative treatments are required and now the cancer stem cells (CSCs) are expected to be an effective target for novel therapies. Therefore we investigated the significance of hedgehog (Hh) signaling in the maintenance of CSC-like properties of pancreatic cancer cells, in order to discover the key molecules controlling their unique properties.MethodsHuman pancreatic cancer cell lines, Capan-1, PANC-1, MIA PaCa-2 and Capan-1 M9 were used for our experiments in DMEM/F12 medium containing 10 % fetal bovine serum. Sphere formation assay, immunofluorescence staining, flow cytometric analysis and MTT cell viability assay were performed to investigate molecular signals and the efficacy in the treatment of pancreatic cancer cells.ResultsInhibition of the Hh pathway significantly reduced the expression of stem cell marker CD133 and sphere formation, an index of self-renewal capacity, demonstrating the suppression of CSC-like properties. Moreover, the GLI inhibitor GANT61 induced greater reduction in sphere formation and cell viability of pancreatic cancer cells than the smoothened (SMO) inhibitor cyclopamine. This suggests that GLI transcription factors, but not SMO membrane protein, are the key molecules in the Hh pathway. The treatment using GANT61 in combination with the inhibition of mTOR, which is another key molecule in pancreatic CSCs, resulted in the efficient reduction of cell viability and sphere formation of an inhibitor-resistant cell line, showing the strong efficacy and wide range applicability to pancreatic CSC-like cells.ConclusionsThus, this novel combination treatment could be useful for the control of pancreatic cancer by targeting pancreatic CSCs. This is the first report of the efficient elimination of pancreatic cancer stem-like cells by the double blockage of Hh/GLI and mTOR signaling.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-016-0534-2) contains supplementary material, which is available to authorized users.

Exosomes Derived from Human Bone Marrow Mesenchymal Stem Cells Promote Tumor Growth Through Hedgehog Signaling Pathway

“…Subsequently Smo signaling triggers the final mediator of hedgehog signaling, the activation of glioma-associated oncogene (Gli) family of transcription factors, Activation of the Gli proteins stimulates the transcription of hedgehog pathway target genes, including Gli1, which further amplifies the initial hedgehog signal,Gli2 and Ptch [46]. Blockage of Hedgehog signaling pathway has been proved to inhibit tumor initiation, progression and metastasis [47]. Cyclopamine, specifically binds and inhibits Smo receptor, is the first known inhibitor of the Hedgehog pathway.…”

Targeting Cancer Stem Cells with Small Molecules

“…The Gli inhibitor GANT61 induced greater reduction in sphere formation and cell viability of pancreatic cancer cells (PANC-1) compared to the SMO inhibitor cyclopamine. [50] It also reduced the expression of CD133 on the CSC population of PANC-1 cells and was very efficient in selectively killing CSCs when used in combination with mTOR inhibitors, highlighting how targeting multiple pathways can act synergistically against the proliferation of CSCs. Additionally, vismodegib was shown to target SMO and selectively target CSCs in pancreatic cancer cells in vitro.…”

Tongue and Taste Organ Biology and Function: Homeostasis Maintained by Hedgehog Signaling

“…Thus, other SMO inhibitors or inhibitors of downstream components, such as GLI transcription factors, are being pursued as alternative therapeutics (125–127). Studies of Hh suppression in mice with a Gli2 transgene and Smo and Gli2 deletion predict that drugs targeting these pathway components will have adverse effects on taste function (38, 82, 86).…”