Activation Of Hedgehog Signaling Research Articles

AMPK attenuates SHH subgroup medulloblastoma growth and metastasis by inhibiting NF-κB activation

BackgroundMedulloblastoma (MB) is one of the most common malignant pediatric brain tumors. Metastasis and relapse are the leading causes of death in MB patients. The initiation of the SHH subgroup of MB (SHH-MB) is due to the aberrant activation of Sonic Hedgehog (Shh) signaling. However, the mechanisms for its metastasis are still unknown.ResultsAMP-dependent protein kinase (AMPK) restrains the activation of Shh signaling pathway, thereby impeding the proliferation of SHH-MB cells. More importantly, AMPK also hinders the growth and metastasis of SHH-MB cells by regulating NF-κB signaling pathway. Furthermore, Vismodegib and TPCA-1, which block the Shh and NF-κB pathways, respectively, synergistically restrained the growth, migration, and invasion of SHH-MB cells.ConclusionsThis work demonstrates that AMPK functions through two signaling pathways, SHH-GLI1 and NF-κB. AMPK-NF-κB axis is a potential target for molecular therapy of SHH-MB, and the combinational blockade of NF-κB and Shh pathways confers synergy for SHH-MB therapy.

Superenhancer activation of KLHDC8A drives glioma ciliation and hedgehog signaling.

Glioblastoma ranks among the most aggressive and lethal of all human cancers. Self-renewing, highly tumorigenic glioblastoma stem cells (GSCs) contribute to therapeutic resistance and maintain cellular heterogeneity. Here, we interrogated superenhancer landscapes of primary glioblastoma specimens and patient-derived GSCs, revealing a kelch domain-containing gene, specifically Kelch domain containing 8A (KLHDC8A) with a previously unknown function as an epigenetically driven oncogene. Targeting KLHDC8A decreased GSC proliferation and self-renewal, induced apoptosis, and impaired in vivo tumor growth. Transcription factor control circuitry analyses revealed that the master transcriptional regulator SOX2 stimulated KLHDC8A expression. Mechanistically, KLHDC8A bound chaperonin-containing TCP1 (CCT) to promote the assembly of primary cilia to activate hedgehog signaling. KLHDC8A expression correlated with Aurora B/C Kinase inhibitor activity, which induced primary cilia and hedgehog signaling. Combinatorial targeting of Aurora B/C kinase and hedgehog displayed augmented benefit against GSC proliferation. Collectively, superenhancer-based discovery revealed KLHDC8A as what we believe to be a novel molecular target of cancer stem cells that promotes ciliogenesis to activate the hedgehog pathway, offering insights into therapeutic vulnerabilities for glioblastoma treatment.

Genomic Profiling of Metastatic Basal cell Carcinoma Reveals Candidate Drivers of Disease and Therapeutic Targets

Basal cell carcinomas (BCCs) are human beings’ most common malignant tumors. Most are easily managed by surgery or topical therapies, and metastasis is rare. Although BCCs can become locally advanced, metastatic BCCs are very uncommon and may be biologically distinct. We assessed the clinicopathologic characteristics of 17 patients with metastatic BCC and pursued whole-exome sequencing of tumor and germline DNA from 8 patients. Genomic profiling revealed aberrant activation of Hedgehog signaling and alterations in GLI transcriptional regulators and Notch and Hippo signaling. Matched local recurrences of primary BCCs and metastases from 3 patients provided evidence of a clonal origin in all cases. Mutations associated with YAP inhibition were found exclusively in 2 hematogenously-spread lung metastases, and metastatic BCCs were enriched for mutations in the YAP/TAZ-binding domain of TEAD genes. Accordingly, YAP/TAZ nuclear localization was associated with metastatic types and Hippo mutations, suggesting an enhanced oncogenic role in hematogenously-spread metastases. Mutations in RET, HGF, and phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (AKT) signaling were enriched compared with a cohort of low clinical-risk BCCs. Our results implicate Hippo and PI3K/AKT dysregulation in metastatic progression of BCCs, making these potential therapeutic targets in metastatic disease. The common clonal origin of matched recurrent and metastatic BCCs suggests that molecular profiling can assist in determining the nature/origin of poorly differentiated metastatic tumors of uncertain type. Genes and pathways enriched for mutations in this cohort are candidate drivers of metastasis and can be used to identify patients at high risk of metastasis who may benefit from aggressive local treatment and careful clinical follow-up.

Combined Inhibition of Smoothened and the DNA Damage Checkpoint WEE1 Exerts Antitumor Activity in Cholangiocarcinoma.

Cholangiocarcinoma (CCA) is characterized by resistance to chemotherapy and a poor prognosis. Therefore, treatments that can effectively suppress tumor growth are urgently needed. Aberrant activation of hedgehog (HH) signaling has been implicated in several cancers, including those of the hepatobiliary tract. However, the role of HH signaling in intrahepatic CCA (iCCA) has not been completely elucidated. In this study, we addressed the function of the main transducer Smoothened (SMO) and the transcription factors (TFs) GLI1 and GLI2 in iCCA. In addition, we evaluated the potential benefits of the combined inhibition of SMO and the DNA damage kinase WEE1. Transcriptomic analysis of 152 human iCCA samples showed increased expression of GLI1, GLI2, and Patched 1 (PTCH1) in tumor tissues compared with nontumor tissues. Genetic silencing of SMO, GLI1, and GLI2 inhibited the growth, survival, invasiveness, and self-renewal of iCCA cells. Pharmacologic inhibition of SMO reduced iCCA growth and viability in vitro, by inducing double-strand break DNA damage, leading to mitotic arrest and apoptotic cell death. Importantly, SMO inhibition resulted in the activation of the G2-M checkpoint and DNA damage kinase WEE1, increasing the vulnerability to WEE1 inhibition. Hence, the combination of MRT-92 with the WEE1 inhibitor AZD-1775 showed increased antitumor activity in vitro and in iCCA xenografts compared with single treatments. These data indicate that combined inhibition of SMO and WEE1 reduces tumor burden and may represent a strategy for the clinical development of novel therapeutic approaches in iCCA.

Activation of Sonic Hedgehog Signaling Promotes Differentiation of Cortical Layer 4 Neurons via Regulation of Their Cell Positioning.

Neuronal subtypes in the mammalian cerebral cortex are determined by both intrinsic and extrinsic mechanisms during development. However, the extrinsic cues that are involved in this process remain largely unknown. Here, we investigated the role of sonic hedgehog (Shh) in glutamatergic cortical subtype specification. We found that E14.5-born, but not E15.5-born, neurons with elevated Shh expression frequently differentiated into layer 4 subtypes as judged by the cell positioning and molecular identity. We further found that this effect was achieved indirectly through the regulation of cell positioning rather than the direct activation of layer 4 differentiation programs. Together, we provided evidence that Shh, an extrinsic factor, plays an important role in the specification of cortical superficial layer subtypes.

Hyperglycemia Induces Endothelial Dysfunction through Hedgehog Signaling-Mediated TNF-α Production

Abstract: When patients with diabetic factors undergo hemodialysis with an arteriovenous fistula (AVF), the fistula is prone to stenosis with unclear mechanism. As a dynamic barrier between the blood and the vessel wall, the endothelium is easily damaged by molecules in the blood, and the mechanism between its dysfunction and the pathogenesis of AVF is still unclear. In this study, we aimed to investigate the mechanism of endothelial dysfunction, and the interventions of endothelial function to rescue of AVF stenosis. We investigated the release of inflammatory cytokine TNF-α from endothelial cells during AVF stenosis in Diabetes Mellitus, the mechanism of endothelial dysfunction, and the improvement of endothelial cell function to rescue of AVF stenosis after the implementation of interventions in clinical collected data, animal models, and cell-based studies. Our study finds high glucose stimulation could induce inflammatory cytokine TNF-α overproduction and dysfunction of endothelial cells. SMO expression was upregulated in high glucose stimulated endothelial cells, indicating activation of hedgehog signaling. Inhibition of SMO expression either by genetically knockdown or with its inhibitor Cyclopamine (Cyc) efficiently reduced the release of TNF-α and partially reverted the endothelial dysfunction in vitro and in vivo. GLI1 was further confirmed to be a downstream effector of SMO to induce the expression of TNF-α, and its inhibitor could block this effect. This study provides a new perspective that SMO-GLI1 axis as a promising therapeutic target for reducing the release of inflammatory cytokine TNF-α and alleviating endothelial cell dysfunction to prevent AVF stenosis in diabetic patients. Keywords: arteriovenous fistula stenosis; endothelial cell dysfunction; hedgehog signaling pathway; high glucose; inflammatory cytokine. Disclosures: No relevant conflicts of interest to declare. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Targeting Hedgehog Signaling with Glasdegib in Patients with Refractory Sclerotic Chronic Graft vs. Host Disease: A Report of Two Phase I/II Trials

Introduction Sclerotic chronic graft vs. host disease (scGVHD) is characterized by progressive skin fibrosis that often causes limited mobility and poor quality of life. Aberrant activation of hedgehog signaling leading to the differentiation of dermal fibroblasts into collagen-releasing myofibroblasts has been implicated in scGVHD. Targeted inhibition with hedgehog pathway inhibitors ameliorate fibrosis in experimental models. Our objective was to determine the safety and efficacy of glasdegib, an oral antagonist of the hedgehog signalling transducer Smoothened (SMO) in adult patients (pts) with refractory scGVHD. Methods Two independent, single-arm, open-label, phase I/II investigator-initiated studies [NCT03415867, Spanish Transplantation and Cellular Therapy Cooperative Group (GETH); NCT04111497, Fred Hutchinson Cancer Center/Huntsman Cancer Institute/Duke University Medical Center (FHD)] were performed. Adults with active scGVHD after ≥1 (FHD) or ≥2 (GETH) lines of prior therapy were enrolled. The GETH trial followed a 3+3 dose-finding strategy, whereas the FHD trial employed a fixed-dose design. Primary endpoints were dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) in the GETH trial, and safety and tolerability in the FHD trial. Secondary endpoints included efficacy, patient-reported outcomes and biological correlates of response. Glasdegib was administered once daily in continuous 28-day cycles. Individual organs were scored per 2014 NIH cGVHD criteria. A scGVHD partial response (PR) was defined as skin and/or joints score improvement (≥1 point for body surface area [BSA], skin features or joints/fascia scores; ≥2 points for skin/joints tightening or total P-ROM scores) in the absence of worsening in those scores or an increase ≥2 points in the global severity score. Data cut-off was at 12 months from time of glasdegib initiation. Results Twenty (GETH) and 15 (FHD) pts were enrolled who received a median of 4 (range 2-10) and 4 (1-16) prior lines of therapy. The median age was 47 years (range 27-73) and 64 (33-74) in the GETH and FHD studies, respectively. In the GETH trial, 3 pts were included in cohort 1 (50 mg), 3 in cohort 2 (100 mg) and 16 in the expansion cohort (50 mg). All pts in the FHD trial received glasdegib at an initial dose of 50 mg. Frequent treatment-emergent grade (G) ≥2 adverse events (AEs) in the GETH trial included muscle cramps (85%), alopecia (50%) and dysgeusia (35%). Two pts in cohort 2 experienced a DLT (G3 muscle cramps) that resulted in establishment of the MTD at 50 mg. Similarly, G3 muscle cramps were the most frequently reported adverse event (AE) occurring in 33% of pts in the FHD trial. In the FHD study, a pre-specified trial stopping rule was triggered by the emergence of G3 muscle cramps AEs in 5 pts. In the GETH trial, glasdegib dose reductions were undertaken in 10 pts, and 8 pts stopped glasdegib before completion of 12 cycles of therapy. Ten pts remained on treatment beyond 12 months. In the FHD trial, the glasdegib dose was reduced in 5 pts; 12 pts stopped glasdegib before 12 cycles. Two pts remained on treatment for longer than 12 months and one pt remains on glasdegib at 10 months. At the 12-month data cut-off, 9 (45%) pts in the GETH trial achieved a skin BSA score and/or sclerotic features score PR, and 9 (45%) pts had obtained a joints/fascia score response (6 PRs, 3 complete responses). Corresponding findings in the FHD trial were 4 pts (27%; 3 PRs, 1 CR) and 3 pts (20%; 2 PRs, 1 CR). An improvement ≥2 points in the total P-ROM score was observed in 11 (55%) pts in the GETH study and 4 (27%) pts in the FHD study, Additionally, an improvement ≥2 points in the 0-10 skin and/or joint tightening severity scale was reported in 13 (65%) and 4 (31%; 2 pts with missing data) pts in the GETH and FHD trials, respectively. Overall, 13 (65%) pts obtained a scGVHD PR in the GETH trial, with a median time of 2.4 months to response. Likewise, 7 (47%) pts had a scGVHD PR in the FHD group, with a median time of 0.9 months to response. Preliminary correlative studies did not show changes in the distribution of T-cell subpopulations or TCR diversity in the GETH trial. Conclusions Glasdegib demonstrated high rates of clinical activity in heavily pretreated pts with scGVHD, but tolerability was hampered by the emergence of treatment-related muscle cramps. Yet, selected pts derived a sustained benefit from treatment in the absence of limiting toxicities. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

ARL13B promotes angiogenesis and glioma growth by activating VEGFA-VEGFR2 signaling.

Tumor angiogenesis is essential for solid tumor progression, invasion and metastasis. The aim of this study was to identify potential signaling pathways involved in tumor angiogenesis. Genetically engineered mouse models were used to investigate the effects of endothelial ARL13B(ADP-ribosylation factor-like GTPase 13B) over-expression and deficiency on retinal and cerebral vasculature. An intracranially transplanted glioma model and a subcutaneously implanted melanoma model were employed to examine the effects of ARL13B on tumor growth and angiogenesis. Immunohistochemistry was used to measure ARL13B in glioma tissues, and scRNA-seq was used to analyze glioma and endothelial ARL13B expression. GST-fusion protein-protein interaction and co-immunoprecipitation assays were used to determine the ARL13B-VEGFR2 interaction. Immunobloting, qPCR, dual-luciferase reporter assay and functional experiments were performed to evaluate the effects of ARL13B on VEGFR2 activation. Endothelial ARL13B regulated vascular development of both the retina and brain in mice. Also, ARL13B in endothelial cells regulated the growth of intracranially transplanted glioma cells and subcutaneously implanted melanoma cells by controlling tumor angiogenesis. Interestingly, this effect was attributed to ARL13B interaction with VEGFR2, through which ARL13B regulated the membrane and ciliary localization of VEGFR2 and consequently activated its downstream signaling in endothelial cells. Consistent with its oncogenic role, ARL13B was highly expressed in human gliomas, which was well correlated with the poor prognosis of glioma patients. Remarkably, ARL13B, transcriptionally regulated by ZEB1, enhanced the expression of VEGFA by activating Hedgehog signaling in glioma cells. ARL13B promotes angiogenesis and tumor growth by activating VEGFA-VEGFR2 signaling. Thus, targeting ARL13B might serve as a potential approach for developing an anti-glioma or anti-melanoma therapy.

Role of Sonic Hedgehog Signaling Activation in the Prevention of Neurological Abnormalities Associated with Obsessive-Compulsive Disorder.

The smoothened sonic hedgehog (Smo-Shh) pathway is one mechanism that influences neurogenesis, including brain cell differentiation and development during childhood. Shh signaling dysregulation leads to decreased target gene transcription, which contributes to increased neuronal excitation, apoptosis, and neurodegeneration, eventually leading to neurological deficits. Neuropsychiatric disorders such as OCD and related neurological dysfunctions are characterized by neurotransmitter imbalance, neuroinflammation, oxidative stress, and impaired neurogenesis, disturbing the cortico-striato-thalamo-cortical (CSTC) link neuronal network. Despite the availability of several treatments, such as selective serotonin reuptake inhibitors, some individuals may not benefit much from them. Several trials on the use of antipsychotics in the treatment of OCD have also produced inadequate findings. This evidence-based review focuses on a potential pharmacological approach to alleviating OCD and associated neuronal deficits by preventing neurochemical alterations, in which sonic hedgehog activators are neuroprotective, lowering neuronal damage while increasing neuronal maintenance and survival. As a result, stimulating SMO-Shh via its potential activators may have neuroprotective effects on neurological impairment associated with OCD. This review investigates the link between SMO-Shh signaling and the neurochemical abnormalities associated with the progression of OCD and associated neurological dysfunctions. Role of Smo-Shh signaling in serotonergic neurogenesis and in maintaining their neuronal identity. The Shh ligand activates two main transcriptional factors known as Foxa2 and Nkx2.2, which again activates another transcriptional factor, GATA (GATA2 and GATA3), in post mitotic precursor cells of serotonergic neurons-following increased expression of Pet-1 and Lmx1b after GATA regulates the expression of many serotonergic enzymes such as TPH2, SERT, VMAT, slc6a4, Htr1a, Htr1b (Serotonin receptor enzymes), and MAO that regulate and control the release of serotonin and maintain their neuronal identity after their maturation. Abbreviation: Foxa2: Forkhead box; GATA: Globin transcription factor; Lmx1b: LIM homeobox transcription factor 1 beta; TPH2: Tryptophan hydroxylase 2; Htr1a: Serotonin receptor 1a; Htr1b: Serotonin receptor 1b; SERT: Serotonin transporter; VMAT: Vesicular monoamine transporter; MAO: Monoamine oxidase.

Ethanol Effects on Early Developmental Stages Studied Using the Zebrafish.

Fetal alcohol spectrum disorder (FASD) results from prenatal ethanol exposure. The zebrafish (Danio rerio) is an outstanding in vivo FASD model. Early development produced the three germ layers and embryonic axes patterning. A critical pluripotency transcriptional gene circuit of sox2, pou5f1 (oct4; recently renamed pou5f3), and nanog maintain potency and self-renewal. Ethanol affects sox2 expression, which functions with pou5f1 to control target gene transcription. Various genes, like elf3, may interact and regulate sox2, and elf3 knockdown affects early development. Downstream of the pluripotency transcriptional circuit, developmental signaling activities regulate morphogenetic cell movements and lineage specification. These activities are also affected by ethanol exposure. Hedgehog signaling is a critical developmental signaling pathway that controls numerous developmental events, including neural axis specification. Sonic hedgehog activities are affected by embryonic ethanol exposure. Activation of sonic hedgehog expression is controlled by TGF-ß family members, Nodal and Bmp, during dorsoventral (DV) embryonic axis establishment. Ethanol may perturb TGF-ß family receptors and signaling activities, including the sonic hedgehog pathway. Significantly, experiments show that activation of sonic hedgehog signaling rescues some embryonic ethanol exposure effects. More research is needed to understand how ethanol affects early developmental signaling and morphogenesis.

Abstract IA013: Rhabdomyosarcoma: visions through the looking glass

Abstract Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Despite aggressive treatment clinical outcomes for RMS have not improved for three decades, emphasizing the need to uncover the molecular underpinnings of the disease. RMS has been presumed to originate from derailed muscle progenitors based on the histologic appearance and gene expression pattern of the tumors resembling embryonic developing skeletal muscle. However, an origin restricted to skeletal muscle does not explain RMS occurring in tissues devoid of skeletal muscle such as the prostate, bladder, and salivary gland. Previously, we described that activation of Sonic Hedgehog signaling through expression of a conditional, constitutively active Smoothened allele, SmoM2, under control of a presumed adipocyte-restricted adipose protein 2 (aP2)-Cre recombinase transgene in mice gives rise to aggressive skeletal muscle tumors. These tumors display the histologic and molecular characteristics of human embryonal fusion-negative RMS (FN-RMS). This model suggested a potential non-myogenic origin of FN-RMS and an avenue to explain FN-RMS development in anatomic sites devoid of skeletal muscle. Lineage tracing showed that RMS can originate from cell reprogramming and transdifferentiation of endothelial progenitor cells. Hedgehog pathway activation in committed endothelial progenitors results in Tbx1 expression and subsequent Myod1 expression driving a partially myogenic program characteristic of FN-RMS. Our work identifies reprogramming cell fate as a mechanism of transformation in pediatric sarcoma and illustrates that it is dangerous to assume the cell of origin from the characteristics of the tumor cell. The cell-reprogramming mechanism that shifts endothelial progenitors to muscle-like cells provides a unique system to define the core regulatory circuitry controlling RMS cell fate and to determine in vivo if targeting this network is a therapeutic vulnerability. Genomic profiling of human FN-RMS failed to uncover a unique mutation that drives oncogenesis. However, the PTEN cis-regulatory region is hypermethylated in more than 90% of all human FN-ERMS tumors, resulting in decreased expression. However, inhibiting the PI3K/AKT/mTOR pathway has had varied efficacy in RMS. In our RMS mouse model, PTEN localizes to the cytoplasm and nucleus, suggesting that PTEN could have functions other than regulating the PI3K/AKT/mTOR pathway. We demonstrate that Pten loss cooperates in RMS tumorigenesis and results in tumors more reflective of human FN-RMS. We show that Pten loss drives expression of the transcription factor PAX7 and identified PAX7 as a dependency in human FN-RMS. Furthermore, Pax7 deletion completely rescues the deleterious effects of Pten loss but also alters tumor cell fate, giving rise to a smooth muscle tumor. Thus, PTEN loss drives the expression of PAX7, a key member of the RMS core regulatory circuitry dictating tumor cell fate. This highlights a synthetic essential relationship between PTEN and PAX7 in FN-RMS tumor maintenance and tumor-fate decisions. Citation Format: Mark E. Hatley, Casey G. Langdon, Katherine E. Gadek, Matthew R. Garcia, Catherine J. Drummond, Jason A. Hanna, Hongjian E. Jin, Jerold E. Rehg. Rhabdomyosarcoma: visions through the looking glass [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr IA013.

Nodal asymmetry and hedgehog signaling during vertebrate left-right symmetry breaking.

Development of visceral left–right asymmetry in bilateria is based on initial symmetry breaking followed by subsequent asymmetric molecular patterning. An important step is the left-sided expression of transcription factor pitx2 which is mediated by asymmetric expression of the nodal morphogen in the left lateral plate mesoderm of vertebrates. Processes leading to emergence of the asymmetric nodal domain differ depending on the mode of symmetry breaking. In Xenopus laevis and mouse embryos, the leftward fluid flow on the ventral surface of the left–right organizer leads through intermediate steps to enhanced activity of the nodal protein on the left side of the organizer and subsequent asymmetric nodal induction in the lateral plate mesoderm. In the chick embryo, asymmetric morphogenesis of axial organs leads to paraxial nodal asymmetry during the late gastrulation stage. Although it was shown that hedgehog signaling is required for initiation of the nodal expression, the mechanism of its asymmetry remains to be clarified. In this study, we established the activation of hedgehog signaling in early chick embryos to further study its role in the initiation of asymmetric nodal expression. Our data reveal that hedgehog signaling is sufficient to induce the nodal expression in competent domains of the chick embryo, while treatment of Xenopus embryos led to moderate nodal inhibition. We discuss the role of symmetry breaking and competence in the initiation of asymmetric gene expression.

1380P High Sonic Hedgehog (HH) signalling activity, low androgen receptor activity and clonal evolution are associated with resistance to androgen-receptor axis inhibitors in patients with metastatic prostate cancer

The androgen-receptor pathway inhibitors (ARPI) are standard treatment of metastatic castration-resistant prostate cancer (mCRPC). However, the mechanisms of both primary and acquired resistance remain largely unknown.

The epigenetic state of EED-Gli3-Gli1 regulatory axis controls embryonic cortical neurogenesis.

SummaryMutations in the embryonic ectoderm development (EED) cause Weaver syndrome, but whether and how EED affects embryonic brain development remains elusive. Here, we generated a mouse model in which Eed was deleted in the forebrain to investigate the role of EED. We found that deletion of Eed decreased the number of upper-layer neurons but not deeper-layer neurons starting at E16.5. Transcriptomic and genomic occupancy analyses revealed that the epigenetic states of a group of cortical neurogenesis-related genes were altered in Eed knockout forebrains, followed by a decrease of H3K27me3 and an increase of H3K27ac marks within the promoter regions. The switching of H3K27me3 to H3K27ac modification promoted the recruitment of RNA-Pol2, thereby enhancing its expression level. The small molecule activator SAG or Ptch1 knockout for activating Hedgehog signaling can partially rescue aberrant cortical neurogenesis. Taken together, we proposed a novel EED-Gli3-Gli1 regulatory axis that is critical for embryonic brain development.

Bone Marrow Mesenchymal Stem Cells (BMSCs)-Derived miR-206 Promotes Breast Cancer Development by Activating Hedgehog Gene Signaling

Bone marrow-derived mesenchymal stem cells (BMSCs) are an integral part of the tumor microenvironment and involved in tumor evolution. Our aim is to further illuminate the relationship of exosomes of BMSC origin and breast cancer cells in breast cancer. Differential diagnosis was performed by identifying exosomal miR-206 secreted by BMSCs, and RT-PCR detected miR-206 expression in tumor tissues. Transwell assayed cell function and Target scan analyzed the regulatory relationship between Rab23 and miR-206. Rab23 expression was examined by western-blot after the addition of Rab23 and the effect of Rab23 on hedgehog was further verified. We demonstrated that exosomal miR-206 from BMSCs is expressed in tumor tissues and miR-206 mimics significantly inhibited tumor cell invasion and proliferation. miR-206 targets Rab23 and negatively regulates its expression. Further results showed that the addition of Rab23 could activate hedgehog signaling and promote the development of breast cancer. In conclusion, our study reveals that BMSC-derived miR-206 activates hedgehog gene signaling and promotes the breast carcinogenesis development by regulating Rab23 expression.

Non-cell-autonomous activation of hedgehog signaling contributes to disease progression in a mouse model of renal cystic ciliopathy.

Polycystic kidney disease (PKD) is a ciliopathy characterized by fluid-filled epithelial cysts in the kidney. Although it is well established that the primary cilium is essential for hedgehog (HH) signaling and HH signaling is abnormally activated in multiple PKD models, the mechanism and function of HH activation in PKD pathogenesis remain incompletely understood. Here we used a transgenic HH reporter mouse line to identify the target tissue of HH signaling in Arl13f/f;Ksp-Cre mutant kidney, in which the cilia biogenesis gene Arl13b is specifically deleted in epithelial cells of the distal nephron. In addition, we used a co-culture system to dissect cross-talk between epithelial and mesenchymal cells in the absence of expanding cysts. Finally, we treated Arl13bf/f;Ksp-Cre mice with the GLI inhibitor GANT61 and analyzed its impact on PKD progression in this model. We found that deletion of Arl13b in epithelial cells in the mouse kidney, in vivo, led to non-cell-autonomous activation of the HH pathway in the interstitium. In vitro, when co-cultured with mesenchymal cells, Arl13b-/- epithelial cells produced more sonic hedgehog in comparison to cells expressing Arl13b. Reciprocally, HH signaling was activated in mesenchymal cells co-cultured with Arl13b-/- epithelial cells. Finally, whole body inhibition of the HH pathway by GANT61 reduced the number of proliferating cells, inhibited cyst progression and fibrosis and preserved kidney function in Arl13bf/f;Ksp-Cre mice. Our results reveal non-cell-autonomous activation of HH signaling in the interstitium of the Arl13bf/f;Ksp-Cre kidney and suggest that abnormal activation of the HH pathway contributes to disease progression.

Influence of Boron Neutron Capture Therapy on Normal Liver Tissue

Radiation-induced liver diseases, including liver fibrosis, occurs when radiation damages the liver. Basic research on hepatic fibrosis, which is a late radiation injury, is necessary for evaluating adverse liver events occurring after boron neutron capture therapy. This study was conducted to establish a method for analyzing the negative effect such as fibrosis in the liver tissue after boron neutron capture therapy. Female C57BL6 mice were injected with p-boronophenylalanine solution subcutaneously at 2 h before neutron irradiation. Masson trichrome staining was performed to determine the degree of liver fibrosis. The degree of fat accumulation in mouse normal liver tissue after boron neutron capture therapy was evaluated using hematoxylin and eosin staining and triglyceride quantification. Western blotting was performed to determine the expression level of Sonic Hedgehog. Liver fat accumulation and fibrosis were significantly increased in the neutron irradiation group injected with p-boronophenylalanine compared with control group. In addition, Sonic Hedgehog expression was increased in response to boron neutron capture therapy-induced liver injury and was involved in liver fibrosis. Hepatocellular fat accumulation and Hedgehog signaling activation may be indicators of adverse events related to boron neutron capture therapy associated with liver fibrosis.

Shh activation restores interneurons and cognitive function in newborns with intraventricular haemorrhage.

Premature infants with germinal matrix haemorrhage-intraventricular haemorrhage (GMH-IVH) suffer from neurobehavioural deficits as they enter childhood and adolescence. Yet the underlying mechanisms remain unclear. Impaired development and function of interneurons contribute to neuropsychiatric disorders. Therefore, we hypothesized that the occurrence of IVH would reduce interneuron neurogenesis in the medial ganglionic eminence and diminish the population of parvalbumin+ and somatostatin+ cortical interneurons. Because Sonic Hedgehog promotes the production of cortical interneurons, we also postulated that the activation of Sonic Hedgehog signalling might restore neurogenesis, cortical interneuron population, and neurobehavioural function in premature newborns with IVH. These hypotheses were tested in a preterm rabbit model of IVH and autopsy samples from human preterm infants. We compared premature newborns with and without IVH for intraneuronal progenitors, cortical interneurons, transcription factors regulating neurogenesis, single-cell transcriptome of medial ganglionic eminence and neurobehavioural functions. We treated premature rabbit kits with adenovirus expressing Sonic Hedgehog (Ad-Shh) or green fluorescence protein gene to determine the effect of Sonic Hedgehog activation on the interneuron production, cortical interneuron population and neurobehaviour. We discovered that IVH reduced the number of Nkx2.1+ and Dlx2+ progenitors in the medial ganglionic eminence of both humans and rabbits by attenuating their proliferation and inducing apoptosis. Moreover, IVH decreased the population of parvalbumin+ and somatostatin+ neurons in the frontal cortex of both preterm infants and kits relative to controls. Sonic Hedgehog expression and the downstream transcription factors, including Nkx2.1, Mash1, Lhx6 and Sox6, were also reduced in kits with IVH. Consistent with these findings, single-cell transcriptomic analyses of medial ganglionic eminence identified a distinct subpopulation of cells exhibiting perturbation in genes regulating neurogenesis, ciliogenesis, mitochondrial function and MAPK signalling in rabbits with IVH. More importantly, restoration of Sonic Hedgehog level by Ad-Shh treatment ameliorated neurogenesis, cortical interneuron population and neurobehavioural function in kits with IVH. Additionally, Sonic Hedgehog activation alleviated IVH-induced inflammation and several transcriptomic changes in the medial ganglionic eminence. Taken together, IVH reduced intraneuronal production and cortical interneuron population by downregulating Sonic Hedgehog signalling in both preterm rabbits and humans. Notably, activation of Sonic Hedgehog signalling restored interneuron neurogenesis, cortical interneurons and cognitive function in rabbit kits with IVH. These findings highlight disruption in cortical interneurons in IVH and identify a novel therapeutic strategy to restore cortical interneurons and cognitive function in infants with IVH. These studies can accelerate the development of new therapies to enhance the neurodevelopmental outcome of survivors with IVH.

115 The impact of aging on murine basal cell carcinoma development

Basal cell carcinoma (BCC) is the most common skin malignancy and most frequently occurs in patients over 70 years of age. Dysregulated Hedgehog (Hh) signaling and consequent activation of GLI transcription factors is a molecular hallmark of human BCC and drives BCC-like tumor development in genetically engineered mice, which are typically studied at a young age. We examined the impact of aging on BCC tumorigenesis in young versus aged cohorts of Lgr6-CreER;R26-LSL-rtTA;tetO-GLI2A mice, in which topical 4-OHT treatment activates Cre function and rtTA expression in Lgr6+ cells and their progeny, and treatment with doxycycline leads to expression of a tetO-driven activator form of GLI2.

1,3,5,8-Tetrahydroxyxanthone suppressed adipogenesis via activating Hedgehog signaling in 3T3-L1 adipocytes.

In this study, we investigated the effect of 1,3,5,8-tetrahydroxyxanthone (THX) on the adipogenesis of 3T3-L1 adipocytes. THX, a xanthone isolated from Gentianella acuta, inhibited lipid accumulation in 3T3-L1 adipocytes and reduced the protein levels of the key adipogenic transcriptional factors, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), in a dose-dependent manner. In addition, THX enhanced the transcriptional activity of Gli1 known as the key indicator of Hedgehog (Hh) signaling activity and increased the expression of Gli1 and its upstream regulator Smo. The Smo activator SAG exerted the similar effect with THX on regulating Gli1, Smo, PPARγ and C/EBPα expression, which led to the suppression of fat formation in 3T3-L1 adipocytes. Furthermore, we found that the inhibitory effect of THX on adipogenesis was derived from regulation of the early stage of adipogenesis. These results suggest that THX suppresses the differentiation of adipocyte through Hh signaling and may be considered as a potent agent for the prevention of obesity.