ipi-926 and Disease-Models--Animal

Hedgehog (Hh) pathway inhibition in cancer has been evaluated in both the ligand-independent and ligand-dependent settings, where Hh signaling occurs either directly within the cancer cells or within the nonmalignant cells of the tumor microenvironment. Chondrosarcoma is a malignant tumor of cartilage in which there is ligand-dependent activation of Hh signaling. IPI-926 is a potent, orally delivered small molecule that inhibits Hh pathway signaling by binding to Smoothened (SMO). Here, the impact of Hh pathway inhibition on primary chondrosarcoma xenografts was assessed. Mice bearing primary human chondrosarcoma xenografts were treated with IPI-926. The expression levels of known Hh pathway genes, in both the tumor and stroma, and endpoint tumor volumes were measured. Gene expression profiling of tumors from IPI-926-treated mice was conducted to identify potential novel Hh target genes. Hh target genes were studied to determine their contribution to the chondrosarcoma neoplastic phenotype. IPI-926 administration results in downmodulation of the Hh pathway in primary chondrosarcoma xenografts, as demonstrated by evaluation of the Hh target genes GLI1 and PTCH1, as well as inhibition of tumor growth. Chondrosarcomas exhibited autocrine and paracrine Hh signaling, and both were affected by IPI-926. Decreased tumor growth is accompanied by histopathologic changes, including calcification and loss of tumor cells. Gene profiling studies identified genes differentially expressed in chondrosarcomas following IPI-926 treatment, one of which, ADAMTSL1, regulates chondrosarcoma cell proliferation. These studies provide further insight into the role of the Hh pathway in chondrosarcoma and provide a scientific rationale for targeting the Hh pathway in chondrosarcoma.

Topics: ADAMTS Proteins; Animals; Antineoplastic Agents; Calcinosis; Cell Line, Tumor; Cell Proliferation; Chondrosarcoma; Disease Models, Animal; Extracellular Matrix Proteins; Hedgehog Proteins; Humans; Mice; Receptors, G-Protein-Coupled; Signal Transduction; Smoothened Receptor; Tumor Burden; Veratrum Alkaloids; Xenograft Model Antitumor Assays

The Hedgehog (Hh) signaling pathway regulates tissue patterning during development, including patterning and growth of limbs and face, but whether Hh signaling plays a role in adult kidney remains undefined. In this study, using a panel of hedgehog-reporter mice, we show that the two Hh ligands (Indian hedgehog and sonic hedgehog ligands) are expressed in tubular epithelial cells. We report that the Hh effectors (Gli1 and Gli2) are expressed exclusively in adjacent platelet-derived growth factor receptor-β-positive interstitial pericytes and perivascular fibroblasts, suggesting a paracrine signaling loop. In two models of renal fibrosis, Indian Hh ligand was upregulated with a dramatic activation of downstream Gli effector expression. Hh-responsive Gli1-positive interstitial cells underwent 11-fold proliferative expansion during fibrosis, and both Gli1- and Gli2-positive cells differentiated into α-smooth muscle actin-positive myofibroblasts. In the pericyte-like cell line 10T1/2, hedgehog ligand triggered cell proliferation, suggesting a possible role for this pathway in the regulation of cell cycle progression of myofibroblast progenitors during the development of renal fibrosis. The hedgehog antagonist IPI-926 abolished Gli1 induction in vivo but did not decrease kidney fibrosis. However, the transcriptional induction of Gli2 was unaffected by IPI-926, suggesting the existence of smoothened-independent Gli activation in this model. This study is the first detailed description of paracrine hedgehog signaling in adult kidney, which indicates a possible role for hedgehog-Gli signaling in fibrotic chronic kidney disease.

Topics: Animals; Cell Line; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Epithelial Cells; Fibroblasts; Fibrosis; Hedgehog Proteins; Kidney; Kidney Tubules; Kruppel-Like Transcription Factors; Ligands; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Paracrine Communication; Patched Receptors; Pericytes; Receptors, Cell Surface; Signal Transduction; Up-Regulation; Veratrum Alkaloids; Zinc Finger Protein GLI1; Zinc Finger Protein Gli2

Pancreatic ductal adenocarcinoma (PDA) is among the most lethal human cancers in part because it is insensitive to many chemotherapeutic drugs. Studying a mouse model of PDA that is refractory to the clinically used drug gemcitabine, we found that the tumors in this model were poorly perfused and poorly vascularized, properties that are shared with human PDA. We tested whether the delivery and efficacy of gemcitabine in the mice could be improved by coadministration of IPI-926, a drug that depletes tumor-associated stromal tissue by inhibition of the Hedgehog cellular signaling pathway. The combination therapy produced a transient increase in intratumoral vascular density and intratumoral concentration of gemcitabine, leading to transient stabilization of disease. Thus, inefficient drug delivery may be an important contributor to chemoresistance in pancreatic cancer.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Proliferation; Deoxycytidine; Disease Models, Animal; Drug Resistance, Neoplasm; Gemcitabine; Hedgehog Proteins; Humans; Kruppel-Like Transcription Factors; Mice; Neoplasm Transplantation; Neovascularization, Pathologic; Pancreatic Neoplasms; Receptors, G-Protein-Coupled; Signal Transduction; Smoothened Receptor; Stromal Cells; Veratrum Alkaloids; Zinc Finger Protein GLI1

Topics: Animals; Disease Models, Animal; Hedgehog Proteins; Humans; Mice; Pancreatic Neoplasms; Receptors, G-Protein-Coupled; Signal Transduction; Smoothened Receptor; Veratrum Alkaloids