GLI1; GLI family zinc finger 1 (12q13.2-q13.3)

Gene Summary

Gene:GLI1; GLI family zinc finger 1
Aliases: GLI
Summary:This gene encodes a member of the Kruppel family of zinc finger proteins. The encoded transcription factor is activated by the sonic hedgehog signal transduction cascade and regulates stem cell proliferation. The activity and nuclear localization of this protein is negatively regulated by p53 in an inhibitory loop. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2009]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:zinc finger protein GLI1
Updated:14 December, 2014

Cancer Overview

Research Indicators

Publications Per Year (1989-2014)
Graph generated 14 December 2014 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 14 December, 2014 using data from PubMed, MeSH and CancerIndex

Notable (6)

Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Skin, Basal Cell CarcinomaGLI1 and Basal Cell Carcinoma (BCC) - Skin View Publications39
Pancreatic CancerGLI1 and Pancreatic Cancer View Publications28
Brain, MedulloblastomaGLI1 and Medulloblastoma View Publications23
Stomach CancerGLI1 and Stomach Cancer View Publications12
Ewing's SarcomaGLI1 upregulation by EWSR1/FLI1 in Ewing's Sarcoma
Zwerne et al (2008) reported that EWS/FLI1 fusion produces transcriptional upregulation of GLI1 and its direct transcriptional target PATCHED1 in a model transformation system. Joo et al (2009) found that several known EWS/FLI1 targets appear to be targeted through GLI1 suggesting a central role for GLI1 in the pathogenesis of Ewing Tumours.
View Publications6

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Related Links

Latest Publications: GLI1 (cancer-related)

Li N, Chen M, Truong S, et al.
Determinants of Gli2 co-activation of wildtype and naturally truncated androgen receptors.
Prostate. 2014; 74(14):1400-10 [PubMed] Related Publications
BACKGROUND: Gli2, a transcription factor in the Hedgehog pathway, is overexpressed in castrate-resistant prostate cancer (PCa). Previously we showed that Gli2 overexpression increased transcriptional activity of androgen receptor (AR) and conferred androgen growth-independence to normally growth-dependent PCa cells. Here we localized the regions of AR-Gli2 protein interaction and determined the domains within Gli2 needed for AR co-activation.
METHODS: Co-immunoprecipitation and GST-pulldown assays were used to define AR-Gli binding domains. Co-activation assays using androgen-responsive promoter reporters were used to define Gli2 regions needed for AR co-activation. Chromatin immunoprecipitation (ChIP) assays were used to confirm nuclear interactions of Gli2 with AR in PCa cells.
RESULTS: The Gli2 C-terminal domain (CTD) is sufficient for AR co-activation. Two elements within the CTD were required: (1) an AR binding domain within aa628-897; and (2) at least part of the Gli2 transactivation domain within aa1252-1586. In turn, Gli2 binds the tau5/AF5 ligand-independent activation domain in the AR N-terminus. Mutations in the WxxLF motif in tau5/AF5 greatly diminished binding to Gli2-CTD. Gli2 interaction with AR tau5/AF5 was further substantiated by the ability of Gli2/Gli2-CTD to co-activate truncated AR splice variants (AR-V7/ARV567es). ChIP assays confirmed that Gli2 associates with chromatin at androgen response elements found near androgen-responsive genes in LNCaP cells. These assays also showed that AR associates with chromatin containing a Gli-response element near a Gli-responsive gene.
CONCLUSION: Our findings indicate that Gli2 overexpression in PCa cells might support development of castration resistant PCa through AR co-activation and suggests that AR might modulate transcription from Gli2.

Related: Prostate Cancer

Rack PG, Ni J, Payumo AY, et al.
Arhgap36-dependent activation of Gli transcription factors.
Proc Natl Acad Sci U S A. 2014; 111(30):11061-6 [PubMed] Article available free on PMC after 29/01/2015 Related Publications
Hedgehog (Hh) pathway activation and Gli-dependent transcription play critical roles in embryonic patterning, tissue homeostasis, and tumorigenesis. By conducting a genome-scale cDNA overexpression screen, we have identified the Rho GAP family member Arhgap36 as a positive regulator of the Hh pathway in vitro and in vivo. Arhgap36 acts in a Smoothened (Smo)-independent manner to inhibit Gli repressor formation and to promote the activation of full-length Gli proteins. Arhgap36 concurrently induces the accumulation of Gli proteins in the primary cilium, and its ability to induce Gli-dependent transcription requires kinesin family member 3a and intraflagellar transport protein 88, proteins that are essential for ciliogenesis. Arhgap36 also functionally and biochemically interacts with Suppressor of Fused. Transcriptional profiling further reveals that Arhgap36 is overexpressed in murine medulloblastomas that acquire resistance to chemical Smo inhibitors and that ARHGAP36 isoforms capable of Gli activation are up-regulated in a subset of human medulloblastomas. Our findings reveal a new mechanism of Gli transcription factor activation and implicate ARHGAP36 dysregulation in the onset and/or progression of GLI-dependent cancers.

Related: Childhood Medulloblastoma / PNET

Zahreddine HA, Culjkovic-Kraljacic B, Assouline S, et al.
The sonic hedgehog factor GLI1 imparts drug resistance through inducible glucuronidation.
Nature. 2014; 511(7507):90-3 [PubMed] Article available free on PMC after 03/01/2015 Related Publications
Drug resistance is a major hurdle in oncology. Responses of acute myeloid leukaemia (AML) patients to cytarabine (Ara-C)-based therapies are often short lived with a median overall survival of months. Therapies are under development to improve outcomes and include targeting the eukaryotic translation initiation factor (eIF4E) with its inhibitor ribavirin. In a Phase II clinical trial in poor prognosis AML, ribavirin monotherapy yielded promising responses including remissions; however, all patients relapsed. Here we identify a novel form of drug resistance to ribavirin and Ara-C. We observe that the sonic hedgehog transcription factor glioma-associated protein 1 (GLI1) and the UDP glucuronosyltransferase (UGT1A) family of enzymes are elevated in resistant cells. UGT1As add glucuronic acid to many drugs, modifying their activity in diverse tissues. GLI1 alone is sufficient to drive UGT1A-dependent glucuronidation of ribavirin and Ara-C, and thus drug resistance. Resistance is overcome by genetic or pharmacological inhibition of GLI1, revealing a potential strategy to overcome drug resistance in some patients.

Related: Cytarabine Acute Myeloid Leukemia (AML) Signal Transduction

Yue D, Li H, Che J, et al.
Hedgehog/Gli promotes epithelial-mesenchymal transition in lung squamous cell carcinomas.
J Exp Clin Cancer Res. 2014; 33:34 [PubMed] Article available free on PMC after 03/01/2015 Related Publications
BACKGROUND: Squamous cell carcinomas (SCC) account for approximately 30% of non-small cell lung cancer. Investigation of the mechanism of invasion and metastasis of lung SCC will be of great help for the development of meaningful targeted therapeutics. This study is intended to understand whether the activation of Hedgehog (Hh) pathway is involved in lung SCC, and whether activated Hh signaling regulates metastasis through epithelial-mesenchymal transition (EMT) in lung SCC.
METHODS: Two cohorts of patients with lung SCC were studied. Protein expression was examined by immunohistochemistry, Western blot, or immunofluorescence. Protein expression levels in tissue specimens were scored and correlations were analyzed. Vismodegib and a Gli inhibitor were used to inhibit Shh/Gli activity, and recombinant Shh proteins were used to stimulate the Hh pathway in lung SCC cell lines. Cell migration assay was performed in vitro.
RESULTS: Shh/Gli pathway components were aberrantly expressed in lung SCC tissue samples. Gli1 expression was reversely associated with the expression of EMT markers E-Cadherin and β-Catenin in lung SCC specimens. Inhibition of the Shh/Gli pathway suppressed migration and up-regulated E-Cadherin expression in lung SCC cells. Stimulation of the pathway increased migration and down-regulated E-Cadherin expression in lung SCC cells.
CONCLUSIONS: Our results suggested that the Shh/Gli pathway may be critical for lung SCC recurrence, metastasis and resistance to chemotherapy. Inhibition of the Shh/Gli pathway activity/function is a potential therapeutic strategy for the treatment of lung SCC patients.

Related: Lung Cancer Signal Transduction CDH1

Nye MD, Almada LL, Fernandez-Barrena MG, et al.
The transcription factor GLI1 interacts with SMAD proteins to modulate transforming growth factor β-induced gene expression in a p300/CREB-binding protein-associated factor (PCAF)-dependent manner.
J Biol Chem. 2014; 289(22):15495-506 [PubMed] Article available free on PMC after 30/05/2015 Related Publications
The biological role of the transcription factor GLI1 in the regulation of tumor growth is well established; however, the molecular events modulating this phenomenon remain elusive. Here, we demonstrate a novel mechanism underlying the role of GLI1 as an effector of TGFβ signaling in the regulation of gene expression in cancer cells. TGFβ stimulates GLI1 activity in cancer cells and requires its transcriptional activity to induce BCL2 expression. Analysis of the mechanism regulating this interplay identified a new transcriptional complex including GLI1 and the TGFβ-regulated transcription factor, SMAD4. We demonstrate that SMAD4 physically interacts with GLI1 for concerted regulation of gene expression and cellular survival. Activation of the TGFβ pathway induces GLI1-SMAD4 complex binding to the BCL2 promoter whereas disruption of the complex through SMAD4 RNAi depletion impairs GLI1-mediated transcription of BCL2 and cellular survival. Further characterization demonstrated that SMAD2 and the histone acetyltransferase, PCAF, participate in this regulatory mechanism. Both proteins bind to the BCL2 promoter and are required for TGFβ- and GLI1-stimulated gene expression. Moreover, SMAD2/4 RNAi experiments showed that these factors are required for the recruitment of GLI1 to the BCL2 promoter. Finally, we determined whether this novel GLI1 transcriptional pathway could regulate other TGFβ targets. We found that two additional TGFβ-stimulated genes, INTERLEUKIN-7 and CYCLIN D1, are dependent upon the intact GLI1-SMAD-PCAF complex for transcriptional activation. Collectively, these results define a novel epigenetic mechanism that uses the transcription factor GLI1 and its associated complex as a central effector to regulate gene expression in cancer cells.

Related: Cancer of the Pancreas Pancreatic Cancer Signal Transduction SMAD3 MADH4 TGFB1

Mills LD, Zhang L, Marler R, et al.
Inactivation of the transcription factor GLI1 accelerates pancreatic cancer progression.
J Biol Chem. 2014; 289(23):16516-25 [PubMed] Article available free on PMC after 06/06/2015 Related Publications
The role of GLI1 in pancreatic tumor initiation promoting the progression of preneoplastic lesions into tumors is well established. However, its function at later stages of pancreatic carcinogenesis remains poorly understood. To address this issue, we crossed the gli1 knock-out (GKO) animal with cre-dependent pancreatic activation of oncogenic kras concomitant with loss of the tumor suppressor tp53 (KPC). Interestingly, in this model, GLI1 played a tumor-protective function, where survival of GKO/KPC mice was reduced compared with KPC littermates. Both cohorts developed pancreatic cancer without significant histopathological differences in survival studies. However, analysis of mice using ultrasound-based imaging at earlier time points showed increased tumor burden in GKO/KPC mice. These animals have larger tumors, decreased body weight, increased lactate dehydrogenase production, and severe leukopenia. In vivo and in vitro expression studies identified FAS and FAS ligand (FASL) as potential mediators of this phenomenon. The FAS/FASL axis, an apoptotic inducer, plays a role in the progression of pancreatic cancer, where its expression is usually lost or significantly reduced in advanced stages of the disease. Chromatin immunoprecipitation and reporter assays identified FAS and FASL as direct targets of GLI1, whereas GKO/KPC mice showed lower levels of this ligand compared with KPC animals. Finally, decreased levels of apoptosis were detected in tumor tissue in the absence of GLI1 by TUNEL staining. Together, these findings define a novel pathway regulated by GLI1 controlling pancreatic tumor progression and provide a new theoretical framework to help with the design and analysis of trials targeting GLI1-related pathways.

Related: Cancer of the Pancreas Pancreatic Cancer

Gomes DC, Leal LF, Mermejo LM, et al.
Sonic hedgehog signaling is active in human adrenal cortex development and deregulated in adrenocortical tumors.
J Clin Endocrinol Metab. 2014; 99(7):E1209-16 [PubMed] Related Publications
BACKGROUND: The sonic hedgehog (SHH) pathway plays a key role in rodent adrenal cortex development and is involved in tumorigenesis in several human tissues, but data in human adrenal glands are limited.
OBJECTIVES: The objectives of the study were to analyze the involvement of the SHH pathway in human adrenal development and tumorigenesis and the effects of SHH inhibition on an adrenocortical tumor (ACT) cell line.
PATIENTS AND METHODS: Expression of SHH pathway components was evaluated by immunohistochemistry in 51 normal adrenals (33 fetal) and 34 ACTs (23 pediatric) and by quantitative PCR in 81 ACTs (61 pediatric) and 19 controls (10 pediatric). The effects of SHH pathway inhibition on gene expression and cell viability in the NCI-H295A adrenocortical tumor cell line after cyclopamine treatment were analyzed.
RESULTS: SHH pathway proteins were present in fetal and postnatal normal adrenals and showed distinct patterns of spatiotemporal expression throughout development. Adult adrenocortical carcinomas presented with higher expression of PTCH1, SMO, GLI3, and SUFU compared with normal adult adrenal cortices. Conversely, pediatric ACTs showed lower mRNA expression of SHH, PTCH1, SMO, GLI1, and GLI3 compared with normal pediatric adrenal cortices. In vitro treatment with cyclopamine resulted in decreased GLI3, SFRP1, and CTNNB1 mRNA expression and β-catenin staining as well as decreased cell viability.
CONCLUSIONS: The SHH pathway is active in human fetal and postnatal adrenals, up-regulated in adult adrenocortical carcinomas, and down-regulated in pediatric ACTs. SHH pathway antagonism impaired cell viability. The SHH pathway is deregulated in ACTs and might provide a new target therapy to be explored.

Related: Adrenocortical Cancer Adrenocortical Carcinoma - Molecular Biology Signal Transduction

Santini R, Pietrobono S, Pandolfi S, et al.
SOX2 regulates self-renewal and tumorigenicity of human melanoma-initiating cells.
Oncogene. 2014; 33(38):4697-708 [PubMed] Article available free on PMC after 06/06/2015 Related Publications
Melanoma is one of the most aggressive types of human cancer, characterized by enhanced heterogeneity and resistance to conventional therapy at advanced stages. We and others have previously shown that HEDGEHOG-GLI (HH-GLI) signaling is required for melanoma growth and for survival and expansion of melanoma-initiating cells (MICs). Recent reports indicate that HH-GLI signaling regulates a set of genes typically expressed in embryonic stem cells, including SOX2 (sex-determining region Y (SRY)-Box2). Here we address the function of SOX2 in human melanomas and MICs and its interaction with HH-GLI signaling. We find that SOX2 is highly expressed in melanoma stem cells. Knockdown of SOX2 sharply decreases self-renewal in melanoma spheres and in putative melanoma stem cells with high aldehyde dehydrogenase activity (ALDH(high)). Conversely, ectopic expression of SOX2 in melanoma cells enhances their self-renewal in vitro. SOX2 silencing also inhibits cell growth and induces apoptosis in melanoma cells. In addition, depletion of SOX2 progressively abrogates tumor growth and leads to a significant decrease in tumor-initiating capability of ALDH(high) MICs upon xenotransplantation, suggesting that SOX2 is required for tumor initiation and for continuous tumor growth. We show that SOX2 is regulated by HH signaling and that the transcription factors GLI1 and GLI2, the downstream effectors of HH-GLI signaling, bind to the proximal promoter region of SOX2 in primary melanoma cells. In functional studies, we find that SOX2 function is required for HH-induced melanoma cell growth and MIC self-renewal in vitro. Thus SOX2 is a critical factor for self-renewal and tumorigenicity of MICs and an important mediator of HH-GLI signaling in melanoma. These findings could provide the basis for novel therapeutic strategies based on the inhibition of SOX2 for the treatment of a subset of human melanomas.

Related: Apoptosis Melanoma Signal Transduction Skin Cancer SOX2 gene

Yao M, Wang L, Dong Z, et al.
Glypican-3 as an emerging molecular target for hepatocellular carcinoma gene therapy.
Tumour Biol. 2014; 35(6):5857-68 [PubMed] Related Publications
Glypican-3 (GPC-3), a membrane-associated heparan sulfate proteoglycan, plays a crucial role in cell proliferation and metastasis, particularly in hepatocellular carcinoma (HCC) progression, and perhaps is a valuable target for its gene therapy. However, its mechanism remains to be explored. In the present study, the biological behaviors of HCC cells were investigated by interfering GPC-3 gene transcription. After the cells were transfected with specific GPC-3 short hairpin RNA (shRNA), the inhibition of GPC-3 expression was 75.6 % in MHCC-97H or 73.8 % in Huh7 cells at mRNA level; the rates of proliferation and apoptosis were 53.6 and 60.5 % in MHCC-97H or 54.9 and 54.4 % in Huh7 cells, with the cell cycles arrested in the G1 phase; the incidences of cell migration, metastasis, and invasion inhibition were 80.1, 56.4, and 69.1 % in MHCC-97H or 80.9, 59.6, and 58.3 % in Huh7 cells, respectively. The cell biological behaviors were altered by silencing GPC-3 with down-regulation of β-catenin, insulin-like growth factor-II and vascular endothelial growth factor, and Gli1 up-regulation. The cell proliferation was significantly inhibited (up to 95.11 %) by shRNA plus anti-cancer drugs, suggesting that GPC-3 gene should be a potential target for promoting hepatoma cell apoptosis and inhibiting metastasis through the Wnt/β-catenin and Hh singling pathways.

Related: IGF2 Liver Cancer VEGFA CTNNB1 gene

Lynn M, Shah N, Conroy J, et al.
A study of alveolar rhabdomyosarcoma copy number alterations by single nucleotide polymorphism analysis.
Appl Immunohistochem Mol Morphol. 2014; 22(3):213-21 [PubMed] Related Publications
Rhabdomyosarcoma, the most common pediatric soft tissue malignancy arises in 2 major histologic forms: embryonal and alveolar. Classically, the alveolar subtype is characterized by a chromosomal translocation t(2;13)(q35;q14) or t(1;13)(p36;q14) fusing the PAX3 or PAX7 gene, respectively, to the FOXO1 gene, although fusion-negative cases of alveolar rhabdomyosarcoma (ARMS) occur; these share considerably more with the genomic profiles and biological behavior of embryonal rhabdomyosarcoma than with fusion-positive ARMS. The current understanding of any additional genetic aberrations in fusion-positive ARMS is limited. In this study, we evaluated tumor-specific copy number alterations in a cohort of fusion-positive ARMSs using high-resolution technology. The results presented here include previously described changes as well as completely novel findings of copy number alterations in BCR and DICER. The study furthermore highlights associations between fusion type and genotype, as well as outcomes and genotype. Rearrangement of PAX7 is strongly associated with copy number alteration of Glypican 5 (GPC5) and moderately with amplification of IGF1R. There is a moderate association between death from/relapse of disease and, on the one hand, amplification of 12q13.3 (DDIT3; Gli1), and on the other hand, copy number alteration of Wnt6 or LRP1B. Gains of both LRP1B and Gli1 in turn are strongly associated with MycN amplification.

Related: Chromosome 14 Lung Cancer PAX7 gene IGF1R Rhabdomyosarcoma DICER1 DDIT3 gene LRP1B MYCN (n-myc)

Koso H, Tsuhako A, Lyons E, et al.
Identification of FoxR2 as an oncogene in medulloblastoma.
Cancer Res. 2014; 74(8):2351-61 [PubMed] Related Publications
Medulloblastoma is the most common pediatric brain tumor, and in ∼25% of cases, it is driven by aberrant activation of the Sonic Hedgehog (SHH) pathway in granule neuron precursor (GNP) cells. In this study, we identified novel medulloblastoma driver genes through a transposon mutagenesis screen in the developing brain of wild-type and Trp53 mutant mice. Twenty-six candidates were identified along with established driver genes such as Gli1 and Crebbp. The transcription factor FoxR2, the most frequent gene identified in the screen, is overexpressed in a small subset of human medulloblastoma of the SHH subtype. Tgif2 and Alx4, 2 new putative oncogenes identified in the screen, are strongly expressed in the SHH subtype of human medulloblastoma. Mutations in these two genes were mutually exclusive with mutations in Gli1 and tended to cooccur, consistent with involvement in the SHH pathway. Notably, Foxr2, Tgif2, and Alx4 activated Gli-binding sites in cooperation with Gli1, strengthening evidence that they function in SHH signaling. In support of an oncogenic function, Foxr2 overexpression transformed NIH3T3 cells and promoted proliferation of GNPs, the latter of which was also observed for Tgif2 and Alx4. These findings offer forward genetic and functional evidence associating Foxr2, Tgif2, and Alx4 with SHH subtype medulloblastoma.

Related: Childhood Medulloblastoma / PNET Signal Transduction

Liu C, Li D, Hu J, et al.
Chromosomal and genetic imbalances in Chinese patients with rhabdomyosarcoma detected by high-resolution array comparative genomic hybridization.
Int J Clin Exp Pathol. 2014; 7(2):690-8 [PubMed] Article available free on PMC after 06/06/2015 Related Publications
Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in children. Although associations between ARMS tumorigenesis and PAX3, PAX7, and FKHR are well recognized, the complete genetic etiology underlying RMS pathogenesis and progression remains unclear. Chromosomal copy number variations (CNVs) and the involved genes may play important roles in the pathogenesis and progression of human malignancies. Using high-resolution array comparative genomic hybridization (aCGH), we examined 20 formalin-fixed, paraffin-embedded (FFPE) RMS tumors to explore the involvement of the relevant chromosomal regions with resident genes in RMS tumorigenesis. In RMS, frequent gains were identified on chromosome regions 12q13.3-q14.1, 12q24.31, 17q25.1, 1q21.1, and 7q11.23, whereas frequent losses were observed on chromosome regions 5q13.2, 14q32.33, and 15q11.2. Amplifications were observed on chromosome regions 9p13.3, 12q13.3-q14.1, 12q15, and 16p13.11, whereas deletions were detected on chromosome regions 1p36.33, 1p13.1, 2q11.1, 5q13.2, 8p23.1, 9p24.3, and 16p11.2. Frequent gains were detected in GLI1, GEFT, OS9, and CDK4 (12q13.3-q14.1), being 60% in embryonal rhabdomyosarcoma (ERMS) and 66.67% in alveolar rhabdomyosarcoma (ARMS), respectively. However, frequent losses were detected in IGHG1, IGHM, IGHG3, and IGHG4 (14q32.33), being 70% in ERMS and 55.56% in and ARMS, respectively. Frequent gains were detected in TYROBP, HCST, LRFN3, and ALKBH6 (19q13.12) in ERMS but not in ARMS. The frequency of TYROBP, HCST, LRFN3, and ALKBH6 gains is significantly different in ERMS versus ARMS (P=0.011). The results suggest that novel TYROBP, HCST, LRFN3, and ALKBH6 genes may play important roles in ERMS. The technique used is a feasible approach for array comparative genomic hybridization analysis in archival tumor samples.

Related: CGH Rhabdomyosarcoma

Xin Y, Shen XD, Cheng L, et al.
Perifosine inhibits S6K1-Gli1 signaling and enhances gemcitabine-induced anti-pancreatic cancer efficiency.
Cancer Chemother Pharmacol. 2014; 73(4):711-9 [PubMed] Related Publications
PURPOSE: The pancreatic cancer has extremely low overall 5-year survival, and gemcitabine is the only approved single agent for pancreatic cancer treatment.
METHODS: In the present study, we investigated the potential effect of perifosine, a novel Akt inhibitor on gemcitabine-induced anti-pancreatic cancer effect both in vivo and in vitro.
RESULTS: We showed that sub-cytotoxic low concentration of perifosine dramatically enhanced gemcitabine-induced cytotoxicity in cultured pancreatic cancer cells. Perifosine inhibited Akt-mammalian target of rapamycin and Erk-mitogen-activated protein kinase activation in pancreatic cancer cells. Meanwhile, perifosine suppressed the hedgehog signaling, as it inhibited glioma-associated oncogenes (Gli) 1 activation and decreased its target protein patched 1 (PTCH1) expression. Our data demonstrated that perifosine blocked p70S6K1 (S6K1) activation, thus disrupting S6K1-Gli1 association and subsequent Gli1 activation. The reduction of S6K1 or Gli1 expression by target siRNAs inhibited PTCH1 expression and enhanced gemcitabine-induced cytotoxicity in pancreatic cancer cells. Significantly, perifosine dramatically enhanced gemcitabine-mediated antitumor effect in a PANC-1 xenograft severe combined immunodeficiency mice model.
CONCLUSIONS: In summary, we conclude that perifosine sensitizes gemcitabine-mediated anti-pancreatic cancer efficiency through regulating multiple signaling pathways.

Related: Cancer of the Pancreas Pancreatic Cancer AKT1 Signal Transduction Gemcitabine

Noubissi FK, Kim T, Kawahara TN, et al.
Role of CRD-BP in the growth of human basal cell carcinoma cells.
J Invest Dermatol. 2014; 134(6):1718-24 [PubMed] Article available free on PMC after 06/06/2015 Related Publications
Although the number of new cases of basal cell carcinoma (BCC) has increased rapidly in the last few decades, the molecular basis of its pathogenesis is not completely understood. Activation of the Hedgehog (Hh) signaling pathway has been shown to be a key factor driving the development of BCC. The Wnt/β-catenin signaling pathway was also shown to be activated in BCCs and to perhaps modulate the activity of the Hh pathway. We have previously identified a mechanism by which Wnt signaling regulates the transcriptional outcome of the Hh signaling pathway. We demonstrated that coding region determinant-binding protein (CRD-BP), a direct target of the Wnt/β-catenin signaling, binds to GLI1 mRNA, stabilizes it, and consequently upregulates its levels (mRNA and protein) and activities. We hypothesized that Wnt-induced and CRD-BP-dependent regulation of GLI1 expression and activities is important for the development of BCC. In this study, we show that CRD-BP is overexpressed in BCC and that its expression positively correlates with the activation of both Wnt and Hh signaling pathways. We also describe the generation and characterization of a human BCC cell line. This cell line was utilized to demonstrate the importance of CRD-BP-dependent regulation of GLI1 expression and activities in the development of BCC.

Related: Apoptosis Basal Cell Carcinoma Skin Cancer TERT

Gai X, Lu Z, Tu K, et al.
Caveolin-1 is up-regulated by GLI1 and contributes to GLI1-driven EMT in hepatocellular carcinoma.
PLoS One. 2014; 9(1):e84551 [PubMed] Article available free on PMC after 06/06/2015 Related Publications
Caveolin-1 (Cav-1) has been recently identified to be over-expressed in hepatocellular carcinoma (HCC) and promote HCC cell motility and invasion ability via inducing epithelial-mesenchymal transition (EMT). However, the mechanism of aberrant overexpression of Cav-1 remains vague. Here, we observed that Cav-1 expression was positively associated with GLI1 expression in HCC tissues. Forced expression of GLI1 up-regulated Cav-1 in Huh7 cells, while knockdown of GLI1 decreased expression of Cav-1 in SNU449 cells. Additionally, silencing Cav-1 abolished GLI1-induced EMT of Huh7 cells. The correlation between GLI1 and Cav-1 was confirmed in tumor specimens from HCC patients and Cav-1 was found to be associated with poor prognosis after hepatic resection. The relationship between protein expression of GLI1 and Cav-1 was also established in HCC xenografts of nude mice. These results suggest that GLI1 may be attributed to Cav-1 up-regulation which plays an important role in GLI1-driven EMT phenotype in HCC.

Related: Liver Cancer

Zhao Y, Huang J, Zhang L, et al.
MiR-133b is frequently decreased in gastric cancer and its overexpression reduces the metastatic potential of gastric cancer cells.
BMC Cancer. 2014; 14:34 [PubMed] Article available free on PMC after 06/06/2015 Related Publications
BACKGROUND: Emerging evidence has shown that microRNAs are involved in gastric cancer development and progression. Here we examine the role of miR-133b in gastric cancer.
METHODS: Quantitative real-time PCR analysis was performed in 140 patient gastric cancer tissues and 8 gastric cancer cell lines. The effects of miR-133b in gastric cancer cells metastasis were examined by scratch assay, transwell migration and matrigel invasion. In vivo effects of miR-133b were examined in an intraperitoneal mouse tumor model. Targets of miR-133b were predicted by bioinformatics tools and validated by luciferase reporter analyses, western blot, and quantitative real-time PCR.
RESULTS: MiR-133b was significantly downregulated in 70% (98/140) of gastric cancer patients. Expression of miR-133b was negatively correlated with lymph node metastasis of gastric cancer in patients. Similarly, the expression of miR-133b was significantly lower in seven tested gastric cancer cell lines than in the immortalized non-cancerous GES-1 gastric epithelial cells. Overexpression of miR-133b markedly inhibited metastasis of gastric cancer cells in vitro and in vivo. Moreover, the transcriptional factor Gli1 was identified as a direct target for miR-133b. Level of Gli1 protein but not mRNA was decreased by miR-133b. Activity of luciferase with Gli1 3'-untranslated region was markedly decreased by miR-133b in gastric cancer cells. Gli1 target genes, OPN and Zeb2, were also inhibited by miR133b.
CONCLUSIONS: MiR-133b is frequently decreased in gastric cancer. Overexpression of miR-133b inhibits cell metastasis in vitro and in vivo partly by directly suppressing expression of Gli1 protein. These results suggested that miR-133b plays an important role in gastric cancer metastasis.

Related: Stomach Cancer Gastric Cancer

Matsushita S, Onishi H, Nakano K, et al.
Hedgehog signaling pathway is a potential therapeutic target for gallbladder cancer.
Cancer Sci. 2014; 105(3):272-80 [PubMed] Related Publications
Gallbladder cancer (GBC) is a particularly deadly type of cancer with a 5-year survival rate of only 10%. New effective therapeutic strategies are greatly needed. Recently, we have shown that Hedgehog (Hh) signaling is reactivated in various types of cancer and is a potential therapeutic target. However, little is known about the biological significance of Hh signaling in human GBC. In this study, we determined whether Hh signaling could be a therapeutic target in GBC. The Hh transcription factor Gli1 was detected in the nucleus of GBC cells but not in the nucleus of normal gallbladder cells. The expression levels of Sonic Hh (Shh) and Smoothened (Smo) in human GBC specimens (n = 37) were higher than those in normal gallbladder tissue. The addition of exogenous Shh ligand augmented the anchor-dependent and anchor-independent proliferation and invasiveness of GBC cells in vitro. In contrast, inhibiting the effector Smo decreased the anchor-dependent and anchor-independent proliferation. Furthermore, the suppression of Smo decreased GBC cell invasiveness through the inhibition of MMP-2 and MMP-9 expression and inhibited the epithelial-mesenchymal transition. In a xenograft model, tumor volume in Smo siRNA-transfected GBC cells was significantly lower than in control tumors. These results suggest that Hh signaling is elevated in GBC and may be involved in the acquisition of malignant phenotypes, and that Hh signaling may be a potential therapeutic target for GBC.

Related: Gallbladder Cancer MMP2 MMP9: matrix metallopeptidase 9 Signal Transduction

Kerl K, Moreno N, Holsten T, et al.
Arsenic trioxide inhibits tumor cell growth in malignant rhabdoid tumors in vitro and in vivo by targeting overexpressed Gli1.
Int J Cancer. 2014; 135(4):989-95 [PubMed] Related Publications
Rhabdoid tumors are highly aggressive tumors occurring in infants and very young children. Despite multimodal and intensive therapy prognosis remains poor. Molecular analyses have uncovered several deregulated pathways, among them the CDK4/6-Rb-, the WNT- and the Sonic hedgehog (SHH) pathways. The SHH pathway is activated in rhabdoid tumors by GLI1 overexpression. Here, we demonstrate that arsenic trioxide (ATO) inhibits tumor cell growth of malignant rhabdoid tumors in vitro and in a mouse xenograft model by suppressing Gli1. Our data uncover ATO as a promising therapeutic approach to improve prognosis for rhabdoid tumor patients.

Related: Apoptosis Malignant Rhabdoid Tumour Signal Transduction

Piirsoo A, Kasak L, Kauts ML, et al.
Protein kinase inhibitor SU6668 attenuates positive regulation of Gli proteins in cancer and multipotent progenitor cells.
Biochim Biophys Acta. 2014; 1843(4):703-14 [PubMed] Article available free on PMC after 06/06/2015 Related Publications
Observations that Glioma-associated transcription factors Gli1 and Gli2 (Gli1/2), executers of the Sonic Hedgehog (Shh) signaling pathway and targets of the Transforming Growth Factor β (TGF-β) signaling axis, are involved in numerous developmental and pathological processes unveil them as attractive pharmaceutical targets. Unc-51-like serine/threonine kinase Ulk3 has been suggested to play kinase activity dependent and independent roles in the control of Gli proteins in the context of the Shh signaling pathway. This study aimed at investigating whether the mechanism of generation of Gli1/2 transcriptional activators has similarities regardless of the signaling cascade evoking their activation. We also elucidate further the role of Ulk3 kinase in regulation of Gli1/2 proteins and examine SU6668 as an inhibitor of Ulk3 catalytic activity and a compound targeting Gli1/2 proteins in different cell-based experimental models. Here we demonstrate that Ulk3 is required not only for maintenance of basal levels of Gli1/2 proteins but also for TGF-β or Shh dependent activation of endogenous Gli1/2 proteins in human adipose tissue derived multipotent stromal cells (ASCs) and mouse immortalized progenitor cells, respectively. We show that cultured ASCs possess the functional Shh signaling axis and differentiate towards osteoblasts in response to Shh. Also, we demonstrate that similarly to Ulk3 RNAi, SU6668 prevents de novo expression of Gli1/2 proteins and antagonizes the Gli-dependent activation of the gene expression programs induced by either Shh or TGF-β. Our data suggest SU6668 as an efficient inhibitor of Ulk3 kinase allowing manipulation of the Gli-dependent transcriptional outcome.

Related: Cancer Prevention and Risk Reduction Signal Transduction

Li G, van Niekerk D, Miller D, et al.
Molecular fixative enables expression microarray analysis of microdissected clinical cervical specimens.
Exp Mol Pathol. 2014; 96(2):168-77 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
Formalin-fixed tissue has been a mainstay of clinical pathology laboratories, but formalin alters many biomolecules, including nucleic acids and proteins. Meanwhile, frozen tissues contain better-preserved biomolecules, but tissue morphology is affected, limiting their diagnostic utility. Molecular fixatives promise to bridge this gap by simultaneously preserving morphology and biomolecules, enabling clinical diagnosis and molecular analyses on the same specimen. While previous reports have broadly evaluated the use of molecular fixative in various human tissues, we present here the first detailed assessment of the applicability of molecular fixative to both routine histopathological diagnosis and molecular analysis of cervical tissues. Ten specimens excised via the loop electrosurgical excision procedure, which removes conical tissue samples from the cervix, were cut into alternating pieces preserved in either formalin or molecular fixative. Cervical specimens preserved in molecular fixative were easily interpretable, despite featuring more eosinophilic cytoplasm and more recognizable chromatin texture than formalin-fixed specimens. Immunohistochemical staining patterns of p16 and Ki-67 were similar between fixatives, although Ki-67 staining was stronger in the molecular fixative specimens. The RNA of molecular fixative specimens from seven cases representing various dysplasia grades was assessed for utility in expression microarray analysis. Cluster analysis and scatter plots of duplicate samples suggest that data of sufficient quality can be obtained from as little as 50ng of RNA from molecular fixative samples. Taken together, our results show that molecular fixative may be a more versatile substitute for formalin, simultaneously preserving tissue morphology for clinical diagnosis and biomolecules for immunohistochemistry and gene expression analysis.

Related: MKI67 Cervical Cancer

Xiong A, Wei L, Ying M, et al.
Wwox suppresses breast cancer cell growth through modulation of the hedgehog-GLI1 signaling pathway.
Biochem Biophys Res Commun. 2014; 443(4):1200-5 [PubMed] Related Publications
Wwox is a tumor suppressor that is frequently deleted or altered in several cancer types, including breast cancer. Previous studies have shown that ectopic expression of Wwox inhibits proliferation of breast cancer cells. However, the underlying mechanism remains unclear. To better understand the molecular mechanisms of Wwox function, we investigated novel partners of this protein. Utilizing the coimmunoprecipitation assay, we observed a physical association between Wwox and the Gli1 zinc-finger transcription factor involved in the hedgehog pathway. Our results further demonstrated that Wwox expression triggered redistribution of nuclear Gli1 to the cytoplasm. Additionally, ectopic expression of Wwox reduced Gli1 expression in vitro. Furthermore, Gli1 Blocks Wwox-induced breast cancer cell growth inhibition. These findings suggest a functional crosstalk between Wwox and hedgehog-GLI1 signaling pathway in tumorigenesis.

Related: Apoptosis Breast Cancer Signal Transduction

Chung JH, Bunz F
A loss-of-function mutation in PTCH1 suggests a role for autocrine hedgehog signaling in colorectal tumorigenesis.
Oncotarget. 2013; 4(12):2208-11 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
Hedgehog (Hh) signaling is largely suppressed in the normal differentiated tissues of the adult but activated in many cancers. The Hh pathway can either be activated by the expression of Hh ligands, or by mutations that cause constitutive, ligand-independent signaling. Colorectal cancer cells frequently express Hh ligands that are believed to exert paracrine effects on the stromal component of the tumor. Evidence for a more direct role of Hh signaling on the growth and evolution of colorectal cancer cell clones has been lacking. Here, we report a loss-of-function mutation of PTCH1, a tumor suppressor in the Hh pathway, in a colorectal cancer that exhibits transcriptional upregulation of the downstream Hh gene GLI1. This finding demonstrates that autocrine Hh signaling can provide a selective advantage to evolving tumors that arise in the colorectal epithelia, and suggests a definable group of colorectal cancer patients that could derive enhanced benefit from Hh pathway inhibitors.

Related: Colorectal (Bowel) Cancer Signal Transduction

Yu D, Shin HS, Lee YS, et al.
Genistein attenuates cancer stem cell characteristics in gastric cancer through the downregulation of Gli1.
Oncol Rep. 2014; 31(2):673-8 [PubMed] Related Publications
Genistein is an isoflavone from soy with multiple action targets in cellular processes. Hedgehog signaling and its activator Gli1 are involved not only in oncogenesis, but also in cancer stemness and overexpression of CD44, a typical cancer stem cell surface marker. It has been shown that levels of Gli1 and CD44 expression are downregulated by genistein. Genistein may modulate distinctive cellular characteristics in cancer stem cells by inhibiting Gli1-related signaling pathways. In the present study, we sorted cells from MKN45, a human gastric cancer cell line, according to CD44 expression. CD44(+) cells showed properties of cancer stem-like cells and formed sphere colonies. In addition, sonic hedgehog (Shh) signaling genes were upregulated in CD44(+) cells when compared with these levels in CD44(-) cells. When CD44(+) cancer stem-like cells were treated with genistein, Gli1 and CD44 mRNA and protein expression was significantly reduced. Moreover, other stem cell markers were downregulated by genistein. Gli1 siRNA was used to confirm the action of genistein in inhibiting Gli1 expression. The high cell migration capacity of CD44(+) cells was blocked by genistein. in conclusion, genistein inhibits Gli1 gene expression, resulting in the attenuation of cancer stem-like properties in gastric cancer cells. In addition, genistein suppresses the cell invasive capacity that is required for tumor growth and metastasis. Our data showed that genistein can be an effective agent for gastric cancer therapy by targeting cancer stem-like characteristics.

Related: Signal Transduction Stomach Cancer Gastric Cancer ABCG2

Sheng W, Dong M, Zhou J, et al.
The clinicopathological significance and relationship of Gli1, MDM2 and p53 expression in resectable pancreatic cancer.
Histopathology. 2014; 64(4):523-35 [PubMed] Related Publications
AIMS: To study the expression of Gli1, MDM2 and p53 for clinical significance in pancreatic cancer (PC), and their functional relationship in regulating the biological behaviour of PC cells.
METHODS AND RESULTS: Immunohistochemistry showed that the expression of Gli1, MDM2 and p53 was much higher in 57 cases of PC than in paired normal pancreatic tissues, and was positively associated with tumour UICC stage and T stage (P < 0.05). Patients with expression of Gli1 only or coexpression of Gli1 and MDM2 had significantly worse overall survival than patients with negative expression (P < 0.05). RNA interference showed that p53 knockdown increased the protein level of Gli1 but decreased the level of MDM2, and enhanced cell invasion and migration in wild-type p53 Capan-2 cells; whereas Gli1 or MDM2 knockdown did not change p53 expression, but decreased the protein level of MDM2 or Gli1, respectively, and inhibited cell invasion and migration in mutant p53 PANC-1 cells.
CONCLUSIONS: Overexpression of Gli1, MDM2 and mutant p53 contributes to the development and progression of PC, and plays an important role in predicting PC patients' prognosis. Moreover, we report a positive association between Gli1 and MDM2 in PC cells, but their relationship with p53 is dependent on wild-type or mutant p53 status.

Related: MMP9: matrix metallopeptidase 9 Cancer of the Pancreas Pancreatic Cancer AKT1 MDM2 gene TP53

Fertig EJ, Markovic A, Danilova LV, et al.
Preferential activation of the hedgehog pathway by epigenetic modulations in HPV negative HNSCC identified with meta-pathway analysis.
PLoS One. 2013; 8(11):e78127 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
Head and neck squamous cell carcinoma (HNSCC) is largely divided into two groups based on their etiology, human papillomavirus (HPV)-positive and -negative. Global DNA methylation changes are known to drive oncogene and tumor suppressor expression in primary HNSCC of both types. However, significant heterogeneity in DNA methylation within the groups results in different transcriptional profiles and clinical outcomes. We applied a meta-pathway analysis to link gene expression changes to DNA methylation in distinguishing HNSCC subtypes. This approach isolated specific epigenetic changes controlling expression in HPV- HNSCC that distinguish it from HPV+ HNSCC. Analysis of genes identified Hedgehog pathway activation specific to HPV- HNSCC. We confirmed that GLI1, the primary Hedgehog target, showed higher expression in tumors compared to normal samples with HPV- tumors having the highest GLI1 expression, suggesting that increased expression of GLI1 is a potential driver in HPV- HNSCC. Our algorithm for integration of DNA methylation and gene expression can infer biologically significant molecular pathways that may be exploited as therapeutics targets. Our results suggest that therapeutics targeting the Hedgehog pathway may be of benefit in HPV- HNSCC. Similar integrative analysis of high-throughput coupled DNA methylation and expression datasets may yield novel insights into deregulated pathways in other cancers.

Related: Head and Neck Cancers Head and Neck Cancers - Molecular Biology Signal Transduction

Du WZ, Feng Y, Wang XF, et al.
Curcumin suppresses malignant glioma cells growth and induces apoptosis by inhibition of SHH/GLI1 signaling pathway in vitro and vivo.
CNS Neurosci Ther. 2013; 19(12):926-36 [PubMed] Related Publications
AIMS: To study the role of curcumin on glioma cells via the SHH/GLI1 pathway in vitro and vivo.
METHODS: The effects of curcumin on proliferation, migration, apoptosis, SHH/GLI1 signaling, and GLI1 target genes expression were evaluated in multiple glioma cell lines in vitro. A U87-implanted nude mice model was used to study the role of curcumin on tumor volume and the suppression efficacy of GLI1.
RESULTS: Curcumin showed cytotoxic effects on glioma cell lines in vitro. Both mRNA and protein levels of SHH/GLI1 signaling (Shh, Smo, GLI1) were downregulated in a dose- and time-dependent manner. Several GLI1-dependent target genes (CyclinD1, Bcl-2, Foxm1) were also downregulated. Curcumin treatment prevented GLI1 translocating into the cell nucleus and reduced the concentration of its reporter. Curcumin suppressed cell proliferation, colony formation, migration, and induced apoptosis which was mediated partly through the mitochondrial pathway after an increase in the ratio of Bax to Bcl2. Intraperitoneal injection of curcumin in vivo reduced tumor volume, GLI1 expression, the number of positively stained cells, and prolonged the survival period compared with the control group.
CONCLUSION: This study shows that curcumin holds a great promise for SHH/GLI1 targeted therapy against gliomas.

Related: Apoptosis Signal Transduction

Inaguma S, Riku M, Hashimoto M, et al.
GLI1 interferes with the DNA mismatch repair system in pancreatic cancer through BHLHE41-mediated suppression of MLH1.
Cancer Res. 2013; 73(24):7313-23 [PubMed] Related Publications
The mismatch repair (MMR) system is indispensable for the fidelity of DNA replication, the impairment of which predisposes to the development and progression of many types of cancers. To date, GLI1 transcription factor, a key molecule of the Hedgehog signaling pathway, has been shown to regulate the expression of several genes crucial for a variety of cancer cell properties in many types of cancers, including pancreatic ductal adenocarcinoma (PDAC), but whether GLI1 could control the MMR system was not known. Here, we showed that GLI1 and GLI2 indirectly suppressed the expression of MLH1 in PDAC cells. Through GLI1 target gene screening, we found that GLI1 and GLI2 activated the expression of a basic helix-loop-helix type suppressor BHLHE41/DEC2/SHARP1 through a GLI-binding site in the promoter. Consistent with a previous report that BHLHE41 suppresses the MLH1 promoter activity, we found that the activation of GLI1 led to the BHLHE41-dependent suppression of MLH1, and a double knockdown of GLI1 and GLI2 conversely increased the MLH1 protein in PDAC cells. Using TALEN-based modification of the MLH1 gene, we further showed that GLI1 expression was indeed associated with an increased tolerance to a methylating agent, methylnitrosourea cooperatively with a lower copy number status of MLH1. Finally, GLI1 expression was immunohistochemically related positively with BHLHE41 and inversely with MLH1 in PDAC cells and precancerous lesions of the pancreas. On the basis of these results, we propose that GLI1 depresses the MMR activity and might contribute to the development and progression of PDAC.

Related: Cancer of the Pancreas Pancreatic Cancer Signal Transduction MLH1

Ning H, Mitsui H, Wang CQ, et al.
Identification of anaplastic lymphoma kinase as a potential therapeutic target in Basal Cell Carcinoma.
Oncotarget. 2013; 4(12):2237-48 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
The pathogenesis of BCC is associated with sonic hedgehog (SHH) signaling. Vismodegib, a smoothened inhibitor that targets this pathway, is now in clinical use for advanced BCC patients, but its efficacy is limited. Therefore, new therapeutic options for this cancer are required. We studied gene expression profiling of BCC tumour tissues coupled with laser capture microdissection to identify tumour specific receptor tyrosine kinase expression that can be targeted by small molecule inhibitors. We found a >250 fold increase (FDR<10-4) of the oncogene, anaplastic lymphoma kinase (ALK) as well as its ligands, pleiotrophin and midkine in BCC compared to microdissected normal epidermis. qRT-PCR confirmed increased expression of ALK (p<0.05). Stronger expression of phosphorylated ALK in BCC tumour nests than normal skin was observed by immunohistochemistry. Crizotinib, an FDA-approved ALK inhibitor, reduced keratinocyte proliferation in culture, whereas a c-Met inhibitor did not. Crizotinib significantly reduced the expression of GLI1 and CCND2 (members of SHH-pathway) mRNA by approximately 60% and 20%, respectively (p<0.01). Our data suggest that ALK may increase GLI1 expression in parallel with the conventional SHH-pathway and promote keratinocyte proliferation. Hence, an ALK inhibitor alone or in combination with targeting SHH-pathway molecules may be a potential treatment for BCC patients.

Related: Basal Cell Carcinoma Signal Transduction Skin Cancer Crizotinib (Xalkori)

Lo WW, Wunder JS, Dickson BC, et al.
Involvement and targeted intervention of dysregulated Hedgehog signaling in osteosarcoma.
Cancer. 2014; 120(4):537-47 [PubMed] Related Publications
BACKGROUND: During development, the Hedgehog pathway plays important roles regulating the proliferation and differentiation of chondrocytes, providing a template for growing bone. In this study, the authors investigated the components of dysregulated Hedgehog signaling as potential therapeutic targets for osteosarcoma.
METHODS: Small-molecule agonists and antagonists that modulate the Hedgehog pathway at different levels were used to investigate the mechanisms of dysregulation and the efficacy of Hedgehog blockade in osteosarcoma cell lines. The inhibitory effect of a small-molecule Smoothened (SMO) antagonist, IPI-926 (saridegib), also was examined in patient-derived xenograft models.
RESULTS: An inverse correlation was identified in osteosarcoma cell lines between endogenous glioma-associated oncogene 2 (GLI2) levels and Hedgehog pathway induction levels. Cells with high levels of GLI2 were sensitive to GLI inhibition, but not SMO inhibition, suggesting that GLI2 overexpression may be a mechanism of ligand-independent activation. In contrast, cells that expressed high levels of the Hedgehog ligand gene Indian hedgehog (IHH) and the target genes patched 1 (PTCH1) and GLI1 were sensitive to modulation of both SMO and GLI, suggesting ligand-dependent activation. In 2 xenograft models, active autocrine and paracrine, ligand-dependent Hedgehog signaling was identified. IPI-926 inhibited the Hedgehog signaling interactions between the tumor and the stroma and demonstrated antitumor efficacy in 1 of 2 ligand-dependent models.
CONCLUSIONS: The current results indicate that both ligand-dependent and ligand-independent Hedgehog dysregulation may be involved in osteosarcoma. It is the first report to demonstrate Hedgehog signaling crosstalk between the tumor and the stroma in osteosarcoma. The inhibitory effect of IPI-926 warrants additional research and raises the possibility of using Hedgehog pathway inhibitors as targeted therapeutics to improve treatment for osteosarcoma.

Related: Bone Cancers Osteosarcoma Signal Transduction

Hai B, Qin L, Yang Z, et al.
Transient activation of hedgehog pathway rescued irradiation-induced hyposalivation by preserving salivary stem/progenitor cells and parasympathetic innervation.
Clin Cancer Res. 2014; 20(1):140-50 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
PURPOSE: To examine the effects and mechanisms of transient activation of the Hedgehog pathway on rescuing radiotherapy-induced hyposalivation in survivors of head and neck cancer.
EXPERIMENTAL DESIGN: Mouse salivary glands and cultured human salivary epithelial cells were irradiated by a single 15-Gy dose. The Hedgehog pathway was transiently activated in mouse salivary glands, by briefly overexpressing the Sonic hedgehog (Shh) transgene or administrating smoothened agonist, and in human salivary epithelial cells, by infecting with adenovirus encoding Gli1. The activity of Hedgehog signaling was examined by the expression of the Ptch1-lacZ reporter and endogenous Hedgehog target genes. The salivary flow rate was measured following pilocarpine stimulation. Salivary stem/progenitor cells (SSPC), parasympathetic innervation, and expression of related genes were examined by flow cytometry, salisphere assay, immunohistochemistry, quantitative reverse transcription PCR, Western blotting, and ELISA.
RESULTS: Irradiation does not activate Hedgehog signaling in mouse salivary glands. Transient Shh overexpression activated the Hedgehog pathway in ductal epithelia and, after irradiation, rescued salivary function in male mice, which is related with preservation of functional SSPCs and parasympathetic innervation. The preservation of SSPCs was likely mediated by the rescue of signaling activities of the Bmi1 and Chrm1-HB-EGF pathways. The preservation of parasympathetic innervation was associated with the rescue of the expression of neurotrophic factors such as Bdnf and Nrtn. The expression of genes related with maintenance of SSPCs and parasympathetic innervation in female salivary glands and cultured human salivary epithelial cells was similarly affected by irradiation and transient Hedgehog activation.
CONCLUSIONS: These findings suggest that transient activation of the Hedgehog pathway has the potential to restore salivary gland function after irradiation-induced dysfunction.

Related: Head and Neck Cancers Head and Neck Cancers - Molecular Biology Signal Transduction

Further References

Kinzler KW, Bigner SH, Bigner DD, et al.
Identification of an amplified, highly expressed gene in a human glioma.
Science. 1987; 236(4797):70-3 [PubMed] Related Publications
A gene, termed gli, was identified that is amplified more than 50-fold in a malignant glioma. The gene is expressed at high levels in the original tumor and its derived cell line and is located at chromosome 12 position (q13 to q14.3). The gli gene is a member of a select group of cellular genes that are genetically altered in primary human tumors.

Related: Chromosome 12


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Cite this page: Cotterill SJ. GLI, Cancer Genetics Web: http://www.cancerindex.org/geneweb/GLI.htm Accessed: date

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