Inhibition Of Hedgehog Signaling Research Articles

Molecular Profiling and the Interaction of Somatic Mutations with Transcriptomic Profiles in Non-Melanoma Skin Cancer (NMSC) in a Population Exposed to Arsenic

Exposure to inorganic arsenic (As) is recognized as a risk factor for non-melanoma skin cancer (NMSC). We followed up with 7000 adults for 6 years who were exposed to As. During follow-up, 2.2% of the males and 1.3% of the females developed basal cell carcinoma (BCC), while 0.4% of the male and 0.2% of the female participants developed squamous cell carcinoma (SCC). Using a panel of more than 400 cancer-related genes, we detected somatic mutations (SMs) in the first 32 NMSC samples (BCC = 26 and SCC = 6) by comparing paired (tissue–blood) samples from the same individual and then comparing them to the SM in healthy skin tissue from 16 participants. We identified (a) a list of NMSC-associated SMs, (b) SMs present in both NMSC and healthy skin, and (c) SMs found only in healthy skin. We also demonstrate that the presence of non-synonymous SMs in the top mutated genes (like PTCH1, NOTCH1, SYNE1, PKHD1 in BCC and TP53 in SCC) significantly affects the magnitude of differential expressions of major genes and gene pathways (basal cell carcinoma pathways, NOTCH signaling, IL-17 signaling, p53 signaling, Wnt signaling pathway). These findings may help select groups of patients for targeted therapy, like hedgehog signaling inhibitors, IL17 inhibitors, etc., in the future.

P-EKKE Alleviates Myocardial Infarction (MI) in MI Rats by Inhibiting Hedgehog Signaling Pathway-mediated Inflammation and Inhibiting α-actin Mediated Myocardial Fibrosis

Background: Myocardial infarction (MI) is an ischemic heart disorder that causes apoptosis or necrosis of myocardial cells. Objective: The study aimed to evaluate the effect of P-EKKE on myocardial infarction and explore the associated mechanisms in MI rats. Methods: The MI in rats was established by ligating the left coronary artery of rats; the rats were divided into the MI group (without treatment) and the P-EKKE group (treated with P-EKKE). Normal rats were assigned to the NC group (without treatment) and the sham group (under LAD without ligation). Cardiac function was evaluated using echocardiography. The MI area was measured with TTC staining. Histological analysis was performed to evaluate inflammation (HE staining) and myocardial fibrosis (Masson and immunofluorescence staining). RT-PCR and Western blotting were used to determine Gli-1/SHH expression in myocardial tissues. Results: P-EKKE clearly improved the cardiac function of MI rats. The area of myocardial infarction in MI rats undergoing P-EKKE treatment (P-EKKE group) was found to be predominantly decreased compared to MI rats without treatment (p < 0.05). P-EKKE treatment clearly inhibited apoptosis and increased H3S10ph expression in the area of myocardial infarction of MI rats compared to MI rats without treatment (p < 0.05). P-EKKE treatment significantly alleviated inflammation and decreased myocardial fibrosis in the area of myocardial infarction in MI rats compared to MI rats without treatment (p < 0.05). P-EKKE significantly increased the expression of Gil-1 and SHH in myocardial infarction of MI rats compared to MI rats without treatment (p < 0.05). Conclusion: P-EKKE inhibited myocardial infarction and played an anti-inflammatory and myocardial protective role in MI rats. P-EKKE inhibited myocardial inflammation by activating the hedgehog signaling pathway and inhibited myocardial fibrosis by decreasing α-actin expression.

Abstract 3586: A Hedgehog-dependent signaling axis drives neural plasticity and oncogenic reprogramming in gastroenteropancreatic neuroendocrine tumors

Abstract Background: Neuroendocrine tumors (NETs) represent heterogenous malignancies whose origins and etiology remain poorly understood. Men1-driven reprogramming of neural crest-derived glial cells was recently implicated in NET development. In these studies, aberrant Sonic hedgehog (SHH) pathway activation known to pattern neural cell fate coincided with the neuroendocrine phenotype in mice. Here, we investigated the hypothesis that loss of menin encoded by the MEN1 gene drives SHH-dependent oncogenic reprogramming of NETs by modulating the neural crest cell fate. Methods: Glial cell specific Men1 deletion was accomplished by expressing Cre recombinase downstream of the human glial fibrillary acidic protein promoter (GFAPΔMen1). Hedgehog (HH) activation of Men1-deficient glial cells was blocked by deleting the gene encoding primary ciliary protein Kif3a required for transducing SHH signaling. The resulting GFAPΔMen1 mice were evaluated for NET development and dysregulated hormone profiles. To identify aberrant SHH activation leading to neuroendocrine reprogramming, we performed single cell RNA- and Assay for Transposase Accessible Chromatin sequencing on GFAPΔMen1 NETs and primary glial cultures. Hyperactivation of SHH in human gastroenteropancreatic (GEP)-NETs was confirmed by immunofluorescent staining and western blot. Lastly, primary mouse and human NET organoids were treated with an agonist and inhibitors of HH signaling and evaluated for ERK/AKT activation, proliferation, and transcript fluctuations indicative of neural crest cell reprogramming. Results: GFAPΔMen1 mice developed NETs in the pancreas, pituitary, and small intestine. Astonishingly, impaired SHH activation in GFAP+/Men1−/− cells abolished the development of NETs and restored hormone levels to that of wild type mice. GFAPΔMen1 NETs and glial cultures showed increased SHH signaling and chromatin accessibility of HH pathway genes, whereas additive Kif3a deletion blocked HH activation. Moreover, menin negative glial cells demonstrated a phenotypic shift in neuroglial lineages that suggested SHH-mediated reprogramming of neural crest-derived cells following the loss of menin. Consistent with hyperactive SHH activation in the GFAPΔMen1 mice, human GEP-NETs overexpressed SHH and downstream signaling targets. Functionally, SHH induced ERK/AKT activation, cell proliferation, and neuroendocrine transcript expression in human and mouse NET organoids, whereas pharmacological inhibition of HH signaling reversed these effects. Conclusions: Our observations implicate neural crest-derived glial cells as potential neuroendocrine cell precursors that are susceptible to transformation through increased HH signaling. These studies warrant future investigation into the delivery of Hedgehog inhibitors in the adjuvant setting for NET treatment. Citation Format: Suzann Duan, Ricky A. Sontz, Martin Deymier, Juanita L. Merchant. A Hedgehog-dependent signaling axis drives neural plasticity and oncogenic reprogramming in gastroenteropancreatic neuroendocrine tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3586.

Synthesis and molecular docking simulations of novel azepines based on quinazolinone moiety as prospective antimicrobial and antitumor hedgehog signaling inhibitors

A series of novel azepine derivatives based on quinazolinone moiety was synthesized through the reaction of quinazolinone chalcones (2a–d) either with 2-amino aniline in acidic medium to give diazepines (3a–d) or with 2-aminophenol to offer oxazepine (4a–d). The structure of the synthesized compounds was confirmed via melting points, elemental analyses, and different spectroscopic techniques. Moreover, these newly compounds mode of action was investigated in-silico using molecular docking against the outer membrane protein A (OMPA), exo-1,3-beta-glucanase for their antimicrobial activity, and against Smoothened (SMO), transcription factor glioma-associated homology (SUFU/GLI-1), the main proteins of Hedgehog signaling pathway to inspect their anticancer potential. Our results showed that, diazepine (3a) and oxazepine (4a) offered the highest binding energy against the target OMPA/ exo-1,3-beta-glucanase proteins and exhibited the potent antimicrobial activities against E. coli, P. aeruginosa, S. aureus, B. subtilis, C. Albicans and A. flavus. As well, diazepine (3a) and oxazepine (4a) achieved the best results among the other compounds, in their binding energy against the target SMO, SUFU/GLI-1 proteins. The in-vitro cytotoxic study was done for them on panel of cancer cell lines HCT-116, HepG2, and MCF-7 and normal cell line WI-38. Conclusively, it was revealed that molecular docking in-silico simulations and the in-vitro experiments were agreed. As a result, our findings elucidated that diazepine (3a) and oxazepine (4a), have the potential to be used as antimicrobial agents and as possible cancer treatment medications.

Intervertebral disc-intrinsic Hedgehog signaling maintains disc cell phenotypes and prevents disc degeneration through both cell autonomous and non-autonomous mechanisms

Intervertebral disc degeneration is closely related to abnormal phenotypic changes in disc cells. However, the mechanism by which disc cell phenotypes are maintained remains poorly understood. Here, Hedgehog-responsive cells were found to be specifically localized in the inner annulus fibrosus and cartilaginous endplate of postnatal discs, likely activated by Indian Hedgehog. Global inhibition of Hedgehog signaling using a pharmacological inhibitor or Agc1-CreERT2-mediated deletion of Smo in disc cells of juvenile mice led to spontaneous degenerative changes in annulus fibrosus and cartilaginous endplate accompanied by aberrant disc cell differentiation in adult mice. In contrast, Krt19-CreER-mediated deletion of Smo specifically in nucleus pulposus cells led to healthy discs and normal disc cell phenotypes. Similarly, age-related degeneration of nucleus pulposus was accelerated by genetic inactivation of Hedgehog signaling in all disc cells, but not in nucleus pulposus cells. Furthermore, inactivation of Gli2 in disc cells resulted in partial loss of the vertebral growth plate but otherwise healthy discs, whereas deletion of Gli3 in disc cells largely corrected disc defects caused by Smo ablation in mice. Taken together, our findings not only revealed for the first time a direct role of Hedgehog-Gli3 signaling in maintaining homeostasis and cell phenotypes of annuls fibrosus and cartilaginous endplate, but also identified disc-intrinsic Hedgehog signaling as a novel non-cell-autonomous mechanism to regulate nucleus pulposus cell phenotype and protect mice from age-dependent nucleus pulposus degeneration. Thus, targeting Hedgehog signaling may represent a potential therapeutic strategy for the prevention and treatment of intervertebral disc degeneration.

Pharmacology of Veratrum californicum Alkaloids as Hedgehog Pathway Antagonists.

Veratrum californicum contains steroidal alkaloids that function as inhibitors of hedgehog (Hh) signaling, a pathway involved in the growth and differentiation of cells and normal tissue development. This same Hh pathway is abnormally active for cell proliferation in more than 20 types of cancer. In this current study, alkaloids have been extracted from the root and rhizome of V. californicum, followed by their separation into five fractions using high performance liquid chromatography. Mass spectrometry was used to identify the presence of twenty-five alkaloids, nine more than are commonly cited in literature reports, and the Bruker Compass Data Analysis software was used to predict the molecular formula for every detected alkaloid. The Gli activity of the raw extract and each fraction were compared to 0.1 µM cyclopamine, and fractions 1, 2, and 4 showed increased bioactivity through suppression of the Hh signaling pathway. Fractions 2 and 4 had enhanced bioactivity, but fraction 1 was most effective in inhibiting Hh signaling. The composition of fraction 1 consisted of veratrosine, cycloposine, and potential isomers of each.

Vicious Cycle-Breaking Lipid Nanoparticles Remodeling Multicellular Crosstalk to Reverse Liver Fibrosis.

During liver fibrogenesis, the reciprocal crosstalk among capillarized liver sinusoidal endothelial cells (LSECs), activated hepatic stellate cells (HSCs), and dysfunctional hepatocytes constructs a self-amplifying vicious cycle, greatly exacerbating the disease condition and weakening therapeutic effect. Limited by the malignant cellular interactions, the previous single-cell centric treatment approaches show unsatisfactory efficacy and fail to meet clinical demand. Herein, a vicious cycle-breaking strategy is proposed to target and repair pathological cells separately to terminate the malignant progression of liver fibrosis. Chondroitin sulfate-modified and vismodegib-loaded nanoparticles (CS-NPs/VDG) are designed to efficiently normalize the fenestrae phenotype of LSECs and restore HSCs to quiescent state by inhibiting Hedgehog signaling pathway. In addition, glycyrrhetinic acid-modified and silybin-loaded nanoparticles (GA-NPs/SIB) are prepared to restore hepatocytes function by relieving oxidative stress. The results show successful interruption of vicious cycle as well as distinct fibrosis resolution in two animal models through multiregulation of the pathological cells. This work not only highlights the significance of modulating cellular crosstalk but also provides a promising avenue for developing antifibrotic regimens.

Current Status of Hedgehog Signaling Inhibitors.

The Hedgehog (Hh) signaling pathway plays a crucial role in diverse biological processes such as cell differentiation, proliferation, senescence, tumorigenesis, malignant transformation, and drug resistance. Aberrant Hh signaling, resulting from mutations and excessive activation, can contribute to the development of various diseases during different stages of biogenesis and development. Moreover, it has been linked to unfavorable outcomes in several human cancers, including basal cell carcinoma (BCC), multiple myeloma (MM), melanoma, and breast cancer. Hence, the presence of mutations and excessive activation of the Hh pathway presents obstacles and constraints in the realm of cancer treatment. Extant research has demonstrated that small molecule inhibitors are regarded as the most effective therapeutic approaches for targeting the Hh pathway in contrast to traditional chemotherapy and radiotherapy. Consequently, this review focuses on the present repertoire of small molecule inhibitors that target various components of the Hh pathway, including Hh ligands, Ptch receptors, Smo transmembrane proteins, and Gli nuclear transcription factors. This study provides a comprehensive analysis of small molecules' structural and functional aspects in the preclinical and clinical management of cancer. Additionally, it elucidates the obstacles encountered in targeting the Hh pathway for human cancer therapy and proposes potential therapeutic approaches.

Spatiotemporal modulation of growth factors directs the generation of multilineage mouse embryonic stem cell-derived mammary organoids

Ectodermal appendages, such as the mammary gland (MG), are thought to have evolved from hair-associated apocrine glands to serve the function of milk secretion. Through the directed differentiation of mouse embryonic stem cells (mESCs), here, we report the generation of multilineage ESC-derived mammary organoids (MEMOs). We adapted the skin organoid model, inducing the dermal mesenchyme to transform into mammary-specific mesenchyme via the sequential activation of Bone Morphogenetic Protein 4 (BMP4) and Parathyroid Hormone-related Protein (PTHrP) and inhibition of hedgehog (HH) signaling. Using single-cell RNA sequencing, we identified gene expression profiles that demonstrate the presence of mammary-specific epithelial cells, fibroblasts, and adipocytes. MEMOs undergo ductal morphogenesis in Matrigel and can reconstitute the MG invivo. Further, we demonstrate that the loss of function in placode regulators LEF1 and TBX3 in mESCs results in impaired skin and MEMO generation. In summary, our MEMO model is a robust tool for studying the development of ectodermal appendages, and it provides a foundation for regenerative medicine and disease modeling.

The deubiquitinating enzyme USP44 suppresses hepatocellular carcinoma progression by inhibiting Hedgehog signaling and PDL1 expression

Hepatocellular carcinoma (HCC) is one of the deadliest malignancies in the world. Research into the key genes that maintain the malignant behavior of cancer cells is crucial for the treatment of HCC. Here, we identified ubiquitin‐specific peptidase 44 (USP44), a member of the deubiquitinase family, as a novel regulator of HCC progression. The tumor suppressive function of USP44 was evaluated in a series of in vitro and in vivo experiments. Through quantitative proteomics examination, we demonstrated that USP44 inhibits HCC PDL1 expression by downregulating the Hedgehog (Hh) signaling pathway. Mechanistically, we found that USP44 directly interacts with Itch, an E3 ligase involved in Hh signaling, and promotes the deubiquitination and stabilization of Itch. These events result in the proteasomal degradation of Gli1 and subsequent inactivation of Hh signaling, which ultimately suppresses PDL1 expression and the progression of HCC. Furthermore, the HCC tissue microarray was analyzed by immunohistochemistry to evaluate the pathological relevance of the USP44/Itch/Gli1/PDL1 axis. Finally, the Gli1 inhibitor GANT61 was found to act in synergy with anti-PDL1 therapy. Overall, USP44 can act as a suppressive gene in HCC by modulating Hh signaling, and co-inhibition of Gli1 and PDL1 might be an effective novel combination strategy for treating HCC patients.

The HEDGEHOG-GLI1 pathway is important for fibroproliferative properties in keloids and as a candidate therapeutic target

Keloids are benign fibroproliferative skin tumors caused by aberrant wound healing that can negatively impact patient quality of life. The lack of animal models has limited research on pathogenesis or developing effective treatments, and the etiology of keloids remains unknown. Here, we found that the characteristics of stem-like cells from keloid lesions and the surrounding dermis differ from those of normal skin. Furthermore, the HEDGEHOG (HH) signal and its downstream transcription factor GLI1 were upregulated in keloid patient–derived stem-like cells. Inhibition of the HH-GLI1 pathway reduced the expression of genes involved in keloids and fibrosis-inducing cytokines, including osteopontin. Moreover, the HH signal inhibitor vismodegib reduced keloid reconstituted tumor size and keloid-related gene expression in nude mice and the collagen bundle and expression of cytokines characteristic for keloids in ex vivo culture of keloid tissues. These results implicate the HH-GLI1 pathway in keloid pathogenesis and suggest therapeutic targets of keloids.

The Challenge of Treating Relapsed Myeloid Leukemia in Children with Down Syndrome - a Targeted Analysis Using Patient-Derived Xenograft Models

Background. Myeloid leukemia occurs with a 150-fold increased incidence in children with Down syndrome (ML-DS) and is characterized by distinct disease mechanism and response to treatment. In the context of trisomy 21, somatic GATA1 mutations first initiate preleukemic transient abnormal myelopoiesis, a disorder of fetal liver hematopoiesis. Co-operating events, which target cohesin complex components, epigenetic modifiers or signal transducers including RAS pathway genes (Yoshida 2013, Labuhn M 2019), then drive transformation to ML-DS in 20% of infants with TAM, typically by age 4 years. Abnormal sonic hedgehog signaling was recently associated with trisomy 21 (Galati 2019). Its role in the development of ML-DS is unknown. Hypersensitivity of ML-DS blasts to chemotherapy with cytarabine and other agents accounts at least in part for the more favorable response of ML-DS compared to acute myeloid leukemia of children without DS. Contemporary treatment protocols for ML-DS achieve event-free and overall survival of approx. 89% and 90% at 5 years (Taub 2017). In marked contrast, patients who develop a relapse of ML-DS face a significantly lower probability of survival (EFS 20.9% and OS 22% at 3 years, Raghuram 2023), compared to children with relapsed AML who do not have DS, and appear to be resistant against conventional chemotherapy. Since the few survivors with a relapsed ML-DS are almost exclusively found among patients who first achieve a second remission and then undergo hematopoietic stem cell transplantation, successful identification of agents with efficacy against the blasts of relapsed ML-DS is essential for survival. We tested if blasts of relapsed ML-DS had lost their sensitivity to cytarabine and whether new drugs could be identified that target pathways active in the blasts of ML-DS. Patients, Materials and Methods . We used patient-derived xenografts (PDX) of human ML-DS and relapsed ML-DS blasts in immunodeficient mice (NSG and NSG-W41) to determine in vivo responses to standard chemotherapeutic agents (cytarabine, vincristine) and novel approaches such as demethylating agents (azacytidine), inhibition of histone deacetylation (panobinostat), mTOR (rapamycin), PARP (olaparib), and sonic hedgehog signaling (glasdegib) alone or in combination (glasdegib + cytarabine; panobinostast + azacytidine). Injection of leukemic cells was performed intrafemorally. Endpoint was inhibition of leukemic engraftment compared to control recipients receiving vehicle only. Results.Responses of primary and relapsed ML-DS samples to drugs tested in PDX models showed marked heterogeneity. While some ML-DS samples showed resistance to cytarabine at the time of relapse this was not the universal cause of failure of primary treatment of ML-DS and some blasts of relapsed ML-DS retained sensitivity to cytarabine. Some primary and relapsed ML-DS blasts showed unexpected sensitivity to vincristine, a drug more commonly used to treat acute lymphoblastic leukemia. Despite intriguing rationales we observed no responses of primary and relapsed ML-DS blasts to the PARP inhibitor olaparib, mTOR inhibition by rapamycin and sonic hedgehog inhibition by glasdegib. Conclusions. Loss of hypersensitivity to cytarabine was not universal at the time of ML-DS relapse. Some agents not typically used to treat AML, such as vincristine, showed unexpected efficacy whereas others lacked responses despite a plausible mechanistic rationale. Patient-specific molecular mechanisms underlying relapsed ML-DS are likely to have an impact on drug sensitivity. They should be determined for all patients with relapsed ML-DS to assist identification of targets and selection of drugs in order to establish urgently needed but currently still lacking efficacious treatment for relapsed ML-DS.

Inhibition of Hedgehog signaling ameliorates foam cell formation by promoting autophagy in early atherosclerosis

Macrophages are the origin of most foam cells in the early stage of atherosclerotic plaques. However, the mechanism involved in the formation of macrophage-derived foam cell formation remains unclear. Here, we revealed that the hedgehog (Hh) signaling is critical in autophagy-lysosome pathway regulation and macrophage-derived foam cell formation. Inhibition of Hh signaling by vismodegib ameliorated lipid deposition and oxidative stress level in atherosclerotic plaques in high-fat diet-fed apoE−/− mice. For mechanistic study, how the Hh signaling modulate the process of foam cell formation were accessed afterward. Unexpectedly, we found that suppression of Hh signaling in apoE−/− mice had no significant impact on circulating cholesterol levels, indicating that Hh pathway modulate the procession of atherosclerotic plaque not through a traditional lipid-lowing mechanism. Instead, vismodegib was found to accelerate autophagosomes maturation as well as cholesterol efflux in macrophage-derived foam cell and in turn improve foam cell formation, while autophagy inhibitors (LY294002 or CQ) administration significantly attenuated vismodegib-induced cholesterol efflux and reversed the effect on foam cell formation. Therefore, our result demonstrated that inhibition of the Hh signaling pathway increases cholesterol efflux and ameliorates macrophage-derived foam cell formation by promoting autophagy in vitro. Our data thus suggested a novel therapeutic target of atherosclerosis and indicated the potential of vismodegib to treat atherosclerosis.

Hedgehog signaling and the glioma-associated oncogene in cancer radioresistance.

Tumor radioresistance remains a key clinical challenge. The Hedgehog (HH) signaling pathway and glioma-associated oncogene (GLI) are aberrantly activated in several cancers and are thought to contribute to cancer radioresistance by influencing DNA repair, reactive oxygen species production, apoptosis, autophagy, cancer stem cells, the cell cycle, and the tumor microenvironment. GLI is reported to activate the main DNA repair pathways, to interact with cell cycle regulators like Cyclin D and Cyclin E, to inhibit apoptosis via the activation of B-cell lymphoma-2, Forkhead Box M1, and the MYC proto-oncogene, to upregulate cell stemness related genes (Nanog, POU class 5 homeobox 1, SRY-box transcription factor 2, and the BMI1 proto-oncogene), and to promote cancer stem cell transformation. The inactivation of Patched, the receptor of HH, prevents caspase-mediated apoptosis. This causes some cancer cells to survive while others become cancer stem cells, resulting in cancer recurrence. Combination treatment using HH inhibitors (including GLI inhibitors) and conventional therapies may enhance treatment efficacy. However, the clinical use of HH signaling inhibitors is associated with toxic side effects and drug resistance. Nevertheless, selective HH agonists, which may relieve the adverse effects of inhibitors, have been developed in mouse models. Combination therapy with other pathway inhibitors or immunotherapy may effectively overcome resistance to HH inhibitors. A comprehensive cancer radiotherapy with HH or GLI inhibitor is more likely to enhance cancer treatment efficacy while further studies are still needed to overcome its adverse effects and drug resistance.

Oxidative Stress Induces Skin Pigmentation in Melasma by Inhibiting Hedgehog Signaling.

There is growing evidence that oxidative stress plays a role in melasma and disrupts primary cilia formation. Additionally, primary cilia have been suggested to have an inhibitory role in melanogenesis. This study examined the potential link between oxidative stress, skin hyperpigmentation, and primary cilia. We compared the expression levels of the nuclear factor E2-related factor 2 (NRF2), intraflagellar transport 88 (IFT88), and glioma-associated oncogene homologs (GLIs) in skin samples from patients with melasma, both in affected and unaffected areas. We also explored the roles of NRF2, IFT88, and GLIs in ciliogenesis and pigmentation using cultured adult human keratinocytes, with or without melanocytes. Our findings revealed decreased levels of NRF2, heme oxygenase-1, IFT88, and GLIs in lesional skin from melasma patients. The knockdown of NRF2 resulted in reduced expressions of IFT88 and GLI1, along with fewer ciliated cells. Furthermore, NRF2, IFT88, or GLI1 knockdown led to increased expressions in protease-activated receptor-2 (PAR2), K10, involucrin, tyrosinase, and/or melanin. These effects were reversed by the smoothened agonist 1.1. Calcium also upregulated these proteins, but not NRF2. The upregulation of involucrin and PAR2 after NRF2 knockdown was mitigated with a calcium chelator. In summary, our study suggests that oxidative stress in NRF2-downregulated melasma keratinocytes impedes ciliogenesis and related molecular processes. This inhibition stimulates keratinocyte differentiation, resulting in melanin synthesis and melanosome transfer, ultimately leading to skin hyperpigmentation.

Phosphatidic acid binding to Patched contributes to the inhibition of Smoothened and Hedgehog signaling in Drosophila wing development.

Hedgehog (Hh) signaling controls growth and patterning during embryonic development and homeostasis in adult tissues. Hh binding to the receptor Patched (Ptc) elicits intracellular signaling by relieving Ptc-mediated inhibition of the transmembrane protein Smoothened (Smo). We uncovered a role for the lipid phosphatidic acid (PA) in the regulation of the Hh pathway in Drosophila melanogaster. Deleting the Ptc C-terminal tail or mutating the predicted PA-binding sites within it prevented Ptc from inhibiting Smo in wing discs and in cultured cells. The C-terminal tail of Ptc directly interacted with PA in vitro, an association that was reduced by Hh, and increased the amount of PA at the plasma membrane in cultured cells. Smo also interacted with PA in vitro through a binding pocket located in the transmembrane region, and mutating residues in this pocket reduced Smo activity in vivo and in cells. By genetically manipulating PA amounts in vivo or treating cultured cells with PA, we demonstrated that PA promoted Smo activation. Our findings suggest that Ptc may sequester PA in the absence of Hh and release it in the presence of Hh, thereby increasing the amount of PA that is locally available to promote Smo activation.

Integrated PK/PD Modeling Relates Smoothened Inhibitor Biomarkers to The Heterogeneous Intratumor Disposition of Cetuximab in Pancreatic Cancer Tumor Models

Therapeutic antibodies have shown little efficacy in the treatment of pancreatic ductal adenocarcinomas (PDAC). Tumor desmoplasia, hypovascularity, and poor perfusion result in insufficient tumor cell exposure, contributing to treatment failure. Smoothened inhibitors of hedgehog signaling (sHHi) increase PDAC tumor permeability, perfusion, and drug delivery, and provide a tool to develop a quantitative, mechanistic understanding as to how the temporal dynamics of tumor priming can impact intratumor distribution of monoclonal antibodies (mAb). A linked pharmacokinetic (PK)/pharmacodynamic (PD) model was developed to integrate the plasma and tumor PK of a sHHi priming agent with its effects upon downstream stromal biomarkers Gli1, hyaluronic acid, and interstitial fluid pressure in PDAC patient-derived xenograft (PDX) tumors. In parallel, in situ tumor concentrations of cetuximab (CTX: anti-epidermal growth factor receptor; EGFR) were quantified as a marker for tumor delivery of mAb or antibody-drug conjugates. A minimal, physiologically-based pharmacokinetic (mPBPK) model was constructed to link sHHi effects upon mechanistic effectors of tumor barrier compromise with the intratumor distribution of CTX, and CTX occupancy of EGFR in tumors. Integration of the mPBPK model of mAb deposition and intratumor distribution with the PK/PD model of tumor responses to priming not only identified physiological parameters that are critical for tumor antibody distribution, but also provides insight into dosing regimens that could achieve maximal tumor disposition of therapeutic antibodies under conditions of transient PDAC tumor permeability barrier compromise that mechanistically-diverse tumor priming strategies may achieve.

A phase I trial of sequential dosing of sonidegib and pembrolizumab in advanced solid tumors (aST) and non–small-cell lung cancer (NSCLC).

9093 Background: Pembrolizumab interrupts PD-1/-L1 interaction and is efficacious in many cancers. However, resistance invariably emerges in the majority of patients. Potential mechanisms include activation of compensatory pathways. The inhibition of sonic hedgehog signaling (sHH) was previously shown to induce intra-tumoral (IT) infiltration by CD4+, CD8+ and HLA-DR class II cells. Our preclinical data showed sHH inhibitor enhanced IT penetration by monoclonal antibodies and induced PD-L1 expression. We conducted a phase I study using a novel sequential pulse dosing of sonedegib followed by pembrolizumab in aST with an expansion cohort to determine the maximum tolerated dose (MTD), tolerability and preliminary efficacy. Methods: The dose escalation utilized a 3+3 design to determine the MTD and proceeded to expansion cohort upon determination of the MTD. Patients enrolled to each dose level were observed for dose limiting toxicities (DLTs) during the 1st cycle. The expansion cohort consisted of NSCLC and head/neck squamous cell carcinoma (HNSCC) previously treated by anti-PD1/-L1. The recommended phase 2 dose (RP2D) was determined following the review of the toxicity profile of the combination from all cycles. The study treatment consisted of sonidegib oral daily from day 1 to 8 and pembrolizumab I.V. 200 mg on day 8 on an every 3-week cycle. The sonidegib dose levels explored were 400, 600 and 800 mg. Archival tumor and blood specimens were collected for correlative studies. Adverse events (AEs) were categorized and graded per CTCAE v5.0, and tumor response by RECIST v1.1. Results: The study enrolled a total of 33 patients and 29 received treatment (13 in escalation and 16 in expansion), including patients with NSCLC, HNSCC, skin cancer, gastric cancer and melanoma. The enrollment to the NSCLC cohort is complete and HNSCC continues. No DLT was encountered during dose escalation and the MTD was not reached. The highest planned dose level was selected to proceed to expansion (sonidegib 800mg days 1-8 in combination with pembrolizumab I.V. 200 mg on day 8 on an every 3-week cycle). The expansion cohort proceeded to enroll 15 patients evaluable for AEs (10 NSCLC and 5 HSNCC). Grade 3 and above treatment-related AEs across all patients were hyperglycemia, fatigue, dyspepsia, abdominal pain. The mature efficacy data will be reported at the meeting. Conclusions: The study successfully determined the RP2D of sonidegib when dosed sequentially with pembrolizumab in advanced solid tumors. The AE profile of the combination is similar to that for respective agents given individually. The efficacy data among anti-PD1/-PDL1-treated NSCLC will be reported at the meeting. Clinical trial information: NCT04007744 .

Saikosaponin A alleviates rat liver fibrosis by inhibiting Hedgehog signaling pathway-mediated autophagy and NLRP3 inflammasome

Purpose: To investigate the effect of saikosaponin A (SSa) on liver fibrosis, and the underlying mechanism of action. 
 Methods: Sprague-Dawley (SD) rats were treated with carbon tetrachloride (CCl4) in an in vivo model of liver fibrosis. The effect of SSa on liver fibrosis was determined by spectrophotometry, Sirius staining, and western blotting. The mechanism of SSa in autophagy and NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasome were examined by western blotting. 
 Results: Saikosaponin A treatment reduced CCl4-induced serum aminotransferase (ALT) and aspartate aminotransferase (AST) levels, hydroxyproline (HYP) content, relative protein expression of alpha-smooth muscle actin (α-SMA), as well as Collagen 1 and deposition of collagenous fiber in liver tissues (p < 0.05). Saikosaponin A administration also downregulated the CCl4-induced protein levels of Hedgehog signaling pathway-related proteins that mediate autophagy and the NLRP3 inflammasome in hepatic tissues (p < 0.05). 
 Conclusion: Saikosaponin A mitigates liver fibrosis by suppressing Hedgehog signaling pathway-mediated autophagy and NLRP3 inflammasome in CCl4-induced rats. Thus, SSa is a potential drug for the management of liver fibrosis.

Hedgehog signaling is a potential therapeutic target for vascular calcification

BackgroundPatients with chronic kidney disease (CKD) suffered from vascular calcification (VC), one major contributor for their increased mortality rate. Hedgehog (Hh) signaling plays a crucial role in physiological bone mineralization and is associated with several cardiovascular diseases. However, the molecular changes underlying VC is ill defined and it remains unclear whether Hh signaling intervention affects VC. MethodsWe constructed human primary vascular smooth muscle cell (VSMC) calcification model and performed RNA sequencing. Alizarin red staining and calcium content assay were conducted to identify the occurrence of VC. Three different R packages were applied to determine differentially expressed genes (DEGs). Enrichment analysis and protein–protein interaction (PPI) network analysis were carried out to explore the biological roles of DEGs. qRT-PCR assay was then applied to validate the expression of key genes. By using Connectivity Map (CMAP) analysis, several small molecular drugs targeting these key genes were obtained, including SAG (Hedgehog signaling activator) and cyclopamine (CPN) (Hedgehog signaling inhibitor), which were subsequently used to treat VSMC. ResultsObvious Alizarin red staining and increased calcium content identified the occurrence of VC. By integrating results from three R packages, we totally obtained 166 DEGs (86 up-regulated and 80 down-regulated), which were significantly enriched in ossification, osteoblast differentiation, and Hh signaling. PPI network analysis identified 10 key genes and CMAP analysis predicted several small molecular drugs targeting these key genes including chlorphenamine, isoeugenol, CPN and phenazopyridine. Notably, our in vitro experiment showed that SAG markedly alleviated VSMC calcification, whereas CPN significantly exacerbated VC. ConclusionsOur research provided deeper insight to the pathogenesis of VC and indicated that targeting Hh signaling pathway may represent a potential and effective therapy for VC.