gant-61 and Cell-Transformation--Neoplastic

Myelodysplastic syndromes (MDSs) are stem cell disorders with risk of transformation to acute myeloid leukemia (AML). Gene expression profiling reveals transcriptional expression of GLI1, of Hedgehog (Hh) signaling, in poor-risk MDS/AML. Using a murine model of MDS we demonstrated that constitutive Hh/Gli1 activation accelerated leukemic transformation and decreased overall survival. Hh/Gli1 activation resulted in clonal expansion of phenotypically defined granulocyte macrophage progenitors (GMPs) and acquisition of self-renewal potential in a non-self-renewing progenitor compartment. Transcriptome analysis of GMPs revealed enrichment in gene signatures of self-renewal pathways, operating via direct Gli1 activation. Using human cell lines we demonstrated that in addition to canonical Hh signaling, GLI1 is activated in a Smoothened-independent manner. GLI1 knockdown or inhibition with GANT61 resulted in decreased proliferation and clonogenic potential. Our data suggest that GLI1 activation is frequent in MDS during disease progression and inhibition of GLI1 is an attractive therapeutic target for a subset of patients.

Topics: Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Granulocyte-Macrophage Progenitor Cells; Hedgehog Proteins; Humans; Leukemia, Myeloid, Acute; Myelodysplastic Syndromes; Pyridines; Pyrimidines; Zinc Finger Protein GLI1

The HH signaling pathway is a 'core' signal transduction pathway in pancreatic cancer that promotes the tumorigenesis of pancreatic cancers via enhancing cell proliferation, increasing invasion and metastasis and protecting against apoptosis. In the present study, we found that HH signaling regulates autophagy in pancreatic cancer cells. Activation of HH signaling inhibits autophagy, while inhibition of the HH pathway induces autophagy. Although the role of autophagy in cell survival and apoptosis may depend on tumor type and the microenvironment, our data clearly demonstrated that GANT61-induced autophagy contributed to reduced viability and increased apoptosis in pancreatic cancer cells both in vivo and in vitro, and these effects were reversed by the autophagy inhibitor, 3-MA. We propose that HH signaling by regulating autophagy plays an important role in determining the cellular response to HH-targeted therapy in pancreatic cancer and further investigation of the interaction between autophagy and HH signaling is particularly important.

Topics: Adenocarcinoma; Animals; Apoptosis; Autophagy; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cell Transformation, Neoplastic; Female; Hedgehog Proteins; Humans; Kruppel-Like Transcription Factors; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Invasiveness; Neoplasm Metastasis; Nuclear Proteins; Pancreatic Ducts; Pancreatic Neoplasms; Pyridines; Pyrimidines; Signal Transduction; Transcription Factors; Xenograft Model Antitumor Assays; Zinc Finger Protein GLI1; Zinc Finger Protein Gli2