Hedgehog-GLI Signaling Research Articles

Tumor-derived GLI1 promotes remodeling of the immune tumor microenvironment in melanoma

BackgroundMelanoma progression is based on a close interaction between cancer cells and immune cells in the tumor microenvironment (TME). Thus, a better understanding of the mechanisms controlling TME dynamics and composition will help improve the management of this dismal disease. Work from our and other groups has reported the requirement of an active Hedgehog-GLI (HH-GLI) signaling for melanoma growth and stemness. However, the role of the downstream GLI1 transcription factor in melanoma TME remains largely unexplored.MethodsThe immune-modulatory activity of GLI1 was evaluated in a syngeneic B16F10 melanoma mouse model assessing immune populations by flow cytometry. Murine polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) were differentiated from bone marrow cells and their immunosuppressive ability was assessed by inhibition of T cells. Conditioned media (CM) from GLI1-overexpressing mouse melanoma cells was used to culture PMN-MDSCs, and the effects of CM were evaluated by Transwell invasion assay and T cell inhibition. Cytokine array analysis, qPCR and chromatin immunoprecipitation were performed to explore the regulation of CX3CL1 expression by GLI1. Human monocyte-derived dendritic cells (moDCs) were cultured in CM from GLI1-silenced patient-derived melanoma cells to assess their activation and recruitment. Blocking antibodies anti-CX3CL1, anti-CCL7 and anti-CXCL8 were used for in vitro functional assays.ResultsMelanoma cell-intrinsic activation of GLI1 promotes changes in the infiltration of immune cells, leading to accumulation of immunosuppressive PMN-MDSCs and regulatory T cells, and to decreased infiltration of dendric cells (DCs), CD8 + and CD4 + T cells in the TME. In addition, we show that ectopic expression of GLI1 in melanoma cells enables PMN-MDSC expansion and recruitment, and increases their ability to inhibit T cells. The chemokine CX3CL1, a direct transcriptional target of GLI1, contributes to PMN-MDSC expansion and recruitment. Finally, silencing of GLI1 in patient-derived melanoma cells promotes the activation of human monocyte-derived dendritic cells (moDCs), increasing cytoskeleton remodeling and invasion ability. This phenotype is partially prevented by blocking the chemokine CCL7, but not CXCL8.ConclusionOur findings highlight the relevance of tumor-derived GLI1 in promoting an immune-suppressive TME, which allows melanoma cells to evade the immune system, and pave the way for the design of new combination treatments targeting GLI1.

GLI Transcriptional Targets S100A7 and KRT16 Show Upregulated Expression Patterns in Epidermis Overlying the Tumor Mass in Melanoma Samples.

Although not completely understood, the role of the Hedgehog-GLI (HH-GLI) signaling pathway in melanoma and epithelial skin tumors has been reported before. In this study, we confirmed in various melanoma cell line models that keratin 16 (KRT16) and S100 Calcium-Binding Protein A7 (S100A7) are transcriptional targets of GLI Family Zinc Finger (GLI) proteins. Besides their important role in protecting and maintaining the epidermal barrier, keratins are somehow tightly connected with the S100 family of proteins. We found that stronger expression of KRT16 indeed corresponds to stronger expression of S100A7 in our clinical melanoma samples. We also report a trend regarding staining of GLI1, which corresponds to stronger staining of GLI3, KRT16, and S100A7 proteins. The most interesting of our findings is that all the proteins are detected specifically in the epidermis overlying the tumor, but rarely in the tumor itself. The examined proteins were also not detected in the healthy epidermis at the edges of the sample, suggesting that the staining is specific to the epidermis overlaying the tumor mass. Of all proteins, only S100A7 demonstrated a statistically significant trend regarding tumor staging and staining intensity. Results from our clinical samples prove that immune infiltration is an important feature of melanoma. Pigmentophages and tumor-infiltrating lymphocytes (TIL) demonstrate a significant association with tumor stage, while mononuclear cells are equally present in all stages. For S100A7, we found an association between the number of TILs and staining intensity. Considering these new findings presented in our study, we suggest a more detailed examination of the possible role of the S100A7 protein as a biomarker in melanoma.

Smad4 regulates TGF-β1-mediated hedgehog activation to promote epithelial-to-mesenchymal transition in pancreatic cancer cells by suppressing Gli1 activity

Pancreatic cancer (PC) is an aggressive and metastatic gastrointestinal tumor with a poor prognosis. Persistent activation of the TGF-β/Smad signaling induces PC cell (PCC) invasion and infiltration via epithelial-to-mesenchymal transition (EMT). Hedgehog signaling is a crucial pathway for the development of PC via the transcription factors Gli1/2/3. This study aimed to investigate the underlying molecular mechanisms of action of hedgehog activation in TGF-β1-triggered EMT in PCCs (PANC-1 and BxPc-3). In addition, overexpression and shRNA techniques were used to evaluate the role of Smad4 in TGF-β1-treated PCCs. Our data showed that TGF-β1 promoted PCC invasion and infiltration via Smad2/3-dependent EMT. Hedgehog-Gli signaling axis in PCCs was activated upon TGF-β1 stimulation. Inhibition of hedgehog with cyclopamine effectively antagonized TGF-β1-induced EMT, thereby suggesting that the hedgehog signaling may act as a downstream cascade signaling of TGF-β1. As a key protein that assists the nuclear translocation of Smad2/3, Smad4 was highly expressed in PANC-1 cells, but not in BxPc-3 cells. Conversely, Gli1 expression was low in PANC-1 cells, but high in BxPc-3 cells. Furthermore, knockdown of Smad4 in PANC-1 cells by shRNA inhibited TGF-β1-mediated EMT and collagen deposition. Overexpression of Smad4 did not affect TGF-β1-mediated EMT due to the lack of significant increase in nuclear expression of Smad4. Importantly, Gli1 activity was upregulated by Smad4 knockdown in PANC-1 cells and downregulated by Smad4 overexpression in BxPc-3 cells, indicating that Gli1 may be a negative target protein downstream of Smad4. Thus, Smad4 regulates TGF-β1-mediated hedgehog activation to promote EMT in PCCs by suppressing Gli1 activity.

Alginate microspheres encapsulating hox transcript antisense RNA siRNA regulate the Hedgehog-Gli1 pathway to alleviate epidermal growth factor receptor tyrosine kinase inhibitors resistance.

The long non-coding RNA HOTAIR and the Hedgehog-Gli1 signaling pathway are closely associated with tumor occurrence and drug resistance in various cancers. However, their specific roles in the development of EGFR-TKIs resistance in non-small cell carcinoma remain unclear. To address the issue of EGFR-TKIs resistance, this study utilized the electrospray method to prepare sodium alginate microspheres encapsulating HOTAIR siRNA (SA/HOTAIR siRNA) and investigated its effects on RNA interference (RNAi) in the gefitinib-resistant cell line PC9/GR. Furthermore, the study explored whether HOTAIR could modulate EGFR-TKIs resistance through the Hedgehog-GLi1 signaling pathway. The experimental results showed that sodium alginate (SA) microspheres demonstrated excellent biocompatibility with high encapsulation efficiency and drug-loading capacity, effectively enhancing the silencing efficiency of siRNA. HOTAIR siRNA significantly inhibited the proliferation, migration, and invasion abilities of PC9/GR cells while promoting apoptosis. Additionally, HOTAIR siRNA effectively suppressed tumor growth and downregulated the Hedgehog-GLi1 pathway and anti-apoptotic proteins, which were confirmed in animal experiments. Moreover, SA/HOTAIR siRNA exhibited superior inhibition of cellular and tumor functions compared to using HOTAIR siRNA alone. Clinical research findings indicated that monitoring the expression level of HOTAIR in the serum and urine samples of NSCLC patients before and after receiving EGFR-TKIs treatment can predict the efficacy of EGFR-TKIs to a certain extent. This study provided evidence that HOTAIR siRNA effectively mitigated the development of acquired resistance to EGFR-TKIs by inhibiting the Hedgehog-GLi1 pathway. Furthermore, it introduced a reliable and long-lasting drug delivery system for combating acquired resistance to EGFR-TKIs.

Let’s Talk about Sex Hormone Receptors and Their Physical Interaction with Sonic Hedgehog Protein: A Computational Study with Emphasis on Progesterone Receptor

The mature form of the sonic hedgehog protein (SHH-N) is the main canonical activator of the Hedgehog-GLI signaling pathway whose aberrant activity can lead to the development of hormone-dependent cancers like breast or prostate cancer. In this study, we employed computational methods to explore the potential binding of SHH-N with the progesterone receptor (PR), the sole member of the nuclear sex hormone receptor (SHRs) subfamily not previously linked to SHH-N. Through a combination of molecular docking, robust molecular dynamics (MD) simulations, and free energy calculations, we predicted a stable binding between SHH-N-cholesterol and PR. To validate our findings, we extended our in silico investigation to encompass the complexes between SHH-N-cholesterol and estrogen receptor alpha (ERα) and androgen receptor (AR)—complexes that have been experimentally confirmed in our prior studies. The calculations not only confirmed the stable binding of SHH-N-cholesterol with both ERα and AR but also revealed the strongest binding occurred with ERα, followed by AR and PR, suggesting a non-canonical interaction with potential biological significance. Microsecond-long MD simulations unveiled tight cholesterol binding in the SHRs’ binding sites, and we gained insights into sub-molecular interactions contributing to protein-protein stabilization in complexes involving PR and ERα for the first time. The MM/PBSA calculations indicated comparable binding affinities of PR for progesterone and SHH-N-cholesterol, with ERα exhibiting a more favorable enthalpy of binding with SHH-N-cholesterol than with estradiol.

RMRP accelerates ligamentum flavum hypertrophy by regulating GSDMD-mediated pyroptosis through Gli1 SUMOylation.

Hypertrophy of ligamentum flavum (LF) is a significant contributing factor to lumbar spinal canal stenosis (LSCS). lncRNA plays a vital role in organ fibrosis, but its role in LF fibrosis remains unclear. Our previous findings have demonstrated that Hedgehog-Gli1 signaling is a critical driver leading to LF hypertrophy. Through the RIP experiment, our group found lnc-RMRP was physically associated with Gli1 and exhibited enrichment in Gli1-activated LF cells. Histological studies revealed elevated expression of RMRP in hypertrophic LF. In vitro experiments further confirmed that RMRP promoted Gli1 SUMO modification and nucleus transfer. Mechanistically, RMRP induced GSDMD-mediated pyroptosis, proinflammatory activation, and collagen expression through the Hedgehog pathway. Notably, the mechanical stress-induced hypertrophy of LF in rabbit exhibited analogous pathological changes of LF fibrosis occurred in human and showed enhanced levels of collagen and α-SMA. Knockdown of RMRP resulted in the decreased expression of fibrosis and pyroptosis-related proteins, ultimately ameliorating fibrosis. The above data concluded that RMRP exerts a crucial role in regulating GSDMD-mediated pyroptosis of LF cells via Gli1 SUMOylation, thus indicating that targeting RMRP could serve as a potential and effective therapeutic strategy for LF hypertrophy and fibrosis.

Lobetyolin Alleviates Ferroptosis of Skeletal Muscle in 5/6 Nephrectomized Mice via Activation of Hedgehog-GLI1 Signaling

BackgroundMuscle wasting increases morbidity and mortality and is related to chronic kidney disease (CKD) and dialysis. It is still unclear whether ferroptosis occurs during this progression and whether it is a potential intervention target for the treatment of CKD-related muscle injury. PurposeThe objective is to identify potential compounds for treating ferroptosis and muscle wasting and explore the potential mechanisms in vivo/in vitro. MethodsInitially, we explored whether ferroptosis is present in the skeletal muscle of 5/6 nephrectomized (NPM) mice via RNA-Seq analysis, TUNEL staining, Oil red O staining, MDA/GSH/GSSG level detection and real-time quantitative PCR (qPCR). Subsequently, utilizing our established molecular phenotyping strategy, we screened potential traditional Chinese herb-derived compounds for alleviation of muscle wasting and ferroptosis. HE staining, Oil red O staining, TUNEL staining, immunofluorescence staining, MDA/GSH/GSSG level detection, Fe level detection, western blotting and qPCR were applied to assess the effects of the identified compound on muscle wasting and ferroptosis and explore the potential mechanism. Furthermore, RNA-Seq analysis, ChIP-Seq analysis and further experiments in vitro were performed to determine the role of Hedgehog signaling in the effect of Lobetyolin (LBT) on ferroptosis. ResultsIn NPM mice, skeletal muscle dysfunction, lipogenesis, reduced GSH/GSSG ratio, decreased GSH content, increased MDA production and and higher levels of ferroptosis markers were observed. LBT treatment (30 mg/kg or 50 mg/kg) significantly alleviates skeletal muscle injury by inhibiting ferroptosis. Additionally, in an in vitro investigation, C2C12 cells exposed to Indolyl sulfate (IS) induced ferroptosis and LBT treatment (20 μM and 50 μM) protected C2C12 from such injury, consistent with the results from the in vivo analysis. Furthermore, it was found LBT increased the levels of protein involving Hedgehog signaling pathway (SMO and GLI1), and rescue analysis revealed that this pathway played a crucial role in the regulation of ferroptosis. Further experiments demonstrated that LBT upregulated a series of suppressors of ferroptosis by activating Gli1 transcription. ConclusionLBT alleviates CKD-induced muscle injury by inhibiting ferroptosis through activation of the Hedgehog signaling pathway.

Higher Expressions of SHH and AR Are Associated with a Positive Receptor Status and Have Impact on Survival in a Cohort of Croatian Breast Cancer Patients.

Breast cancers (BC) are usually classified into four molecular subtypes according to the expression of estrogen (ER), progesterone (PR), and human epidermal growth factor 2 (HER2) receptors and proliferation marker Ki-67. Despite available anti-hormonal therapies and due to the inherent propensity of some subtypes to develop metastasis, there is a permanent need to discover new prognostic and predictive biomarkers, as well as therapeutic targets for BC. In this study, we used immunohistochemical staining to determine the expression of androgen receptor (AR) and sonic hedgehog protein (SHH), the main ligand of the Hedgehog-GLI (HH-GLI) signaling pathway, in 185 archival primary BC tissue samples and correlated it with clinicopathological characteristics, molecular subtypes, receptors statuses, and survival in a cohort of Croatian BC patients. Results showed that higher SHH and AR expressions were associated with positive receptor status, but increased SHH expression had a negative impact on survival in receptor-negative BCs. On the contrary, higher AR expression was mostly protective. However, multivariate analysis showed that only higher AR expression could be considered as an independent prognostic biomarker for poorer overall survival in triple-negative breast cancer patients (TNBC) (HR 10.9, 95% CI 1.43–83.67; p = 0.021), what could be Croatian population-related. SHH could be a potential target for treating TNBCs and HER2-enriched BCs, in cases where HH-GLI signaling is canonical (SHH-dependent).

RNA-seq and ChIP-seq Identification of Unique and Overlapping Targets of GLI Transcription Factors in Melanoma Cell Lines.

Simple SummaryThe majority of melanomas show hyperactivation of the MAPK signaling pathway, most often through mutations in BRAF and NRAS. Despite significant progress in therapy, targeting this signaling pathway solely has not been the solution for stopping the progression of this disease. Recently, researchers recognized the involvement of the Hedgehog-GLI (HH-GLI) signaling pathway in melanoma and its crosstalk with the MAPK pathway. In order to identify new HH-GLI-regulated targets that could be involved in the crosstalk with the MAPK pathway, we performed RNA sequencing and ChIP sequencing on three melanoma cell lines. By combining RNA-seq and ChIP-seq results, we successfully validated 15 novel targets of GLI proteins in melanoma cell lines. These findings will contribute to a better understanding of the GLI code and its role in melanoma.Background: Despite significant progress in therapy, melanoma still has a rising incidence worldwide, and novel treatment strategies are needed. Recently, researchers have recognized the involvement of the Hedgehog-GLI (HH-GLI) signaling pathway in melanoma and its consistent crosstalk with the MAPK pathway. In order to further investigate the link between the two pathways and to find new target genes that could be considered for combination therapy, we set out to find transcriptional targets of all three GLI proteins in melanoma. Methods: We performed RNA sequencing on three melanoma cell lines (CHL-1, A375, and MEL224) with overexpressed GLI1, GLI2, and GLI3 and combined them with the results of ChIP-sequencing on endogenous GLI1, GLI2, and GLI3 proteins. After combining these results, 21 targets were selected for validation by qPCR. Results: RNA-seq revealed a total of 808 differentially expressed genes (DEGs) for GLI1, 941 DEGs for GLI2, and 58 DEGs for GLI3. ChIP-seq identified 527 genes that contained GLI1 binding sites in their promoters, 1103 for GLI2 and 553 for GLI3. A total of 15 of these targets were validated in the tested cell lines, 6 of which were detected by both RNA-seq and ChIP-seq. Conclusions: Our study provides insight into the unique and overlapping transcriptional output of the GLI proteins in melanoma. We suggest that our findings could provide new potential targets to consider while designing melanoma-targeted therapy.

Hedgehog-Gli2 Signaling Promotes Chemoresistance in Ovarian Cancer Cells by Regulating MDR1.

BackgroundCisplatin (DDP) resistance remains a key challenge in improving the clinical outcome of patients with ovarian cancer (OC). Gli2 overexpression can lead to DDP resistance in OC cells, but the specific underlying regulatory mechanism remains unclear. The membrane transporter encoding gene MDR1 positively regulates chemotherapy resistance in various cancer types. We evaluated MDR1 as a potential Gli2 downstream target and the contribution of the Gli2/MDR1 axis in promoting DDP resistance in OC cells.MethodsTo generate drug-resistant SKOV3/DDP cells, SKOV3 cells were grown for six months under continuous induction wherein the DDP concentration was steadily increased. Gli2 expression in OC cells with varying DDP sensitivities was detected using western blot. Cell counting kit-8 assays were used to assess the DDP sensitivity of SKOV3, SKOV3/DDP, A2780, and A2780/DDP cells and reversal of DDP resistance in SKOV3/DDP and A2780/DDP cells. Cell proliferation was analyzed using 5-ethynyl-2′-deoxyuridine (EdU) incorporation assays. The transcriptional regulation of MDR1 by Gli2 was determined using luciferase reporter assays. Finally, xenograft OC tumors were generated in nude mice, which were then treated with intraperitoneal DDP or phosphate-buffered saline (PBS) injections to investigate if Gli2 affected DDP resistance in OC in vivo.ResultsDDP-resistant SKOV3/DDP and A2780/DDP cells showed higher expression of Gli2 and MDR1 as compared with that in DDP-sensitive OC cells. Gli2 knockdown in SKOV3/DDP cells significantly reduced MDR1 expression, whereas it increased DNA damage, thereby sensitizing OC cells to DDP. Similar results were obtained after targeting Gli2 expression with the Gli-antagonist 61 inhibitor (GANT61) in SKOV3/DDP and A2780/DDP cells. In cells stably overexpressing Gli2, treatment with gradient concentrations of verapamil, an MDR1 inhibitor, significantly inhibited MDR1 expression. Our findings indicate that downregulation of MDR1 expression may reverse OC cell resistance to DDP. Moreover, dual-luciferase reporter gene assays confirmed that MDR1 is a direct downstream target of Gli2, with Gli2 positively regulating MDR1 expression. Finally, subcutaneous xenotransplantation in nude mice demonstrated that Gli2 plays a key role in regulating OC drug resistance.ConclusionsWe identified a mechanism by which Hedgehog-Gli signaling regulates OC chemoresistance by modulating MDR1 expression. Hence, Gli2 and MDR1 are potential biomarkers and therapeutic targets in patients with chemoresistant OC.

The Hedgehog-GLI Pathway Regulates MEK5-ERK5 Expression and Activation in Melanoma Cells.

Malignant melanoma is the deadliest skin cancer, with a poor prognosis in advanced stages. We recently showed that the extracellular signal-regulated kinase 5 (ERK5), encoded by the MAPK7 gene, plays a pivotal role in melanoma by regulating cell functions necessary for tumour development, such as proliferation. Hedgehog-GLI signalling is constitutively active in melanoma and is required for proliferation. However, no data are available in literature about a possible interplay between Hedgehog-GLI and ERK5 pathways. Here, we show that hyperactivation of the Hedgehog-GLI pathway by genetic inhibition of the negative regulator Patched 1 increases the amount of ERK5 mRNA and protein. Chromatin immunoprecipitation showed that GLI1, the major downstream effector of Hedgehog-GLI signalling, binds to a functional non-canonical GLI consensus sequence at the MAPK7 promoter. Furthermore, we found that ERK5 is required for Hedgehog-GLI-dependent melanoma cell proliferation, and that the combination of GLI and ERK5 inhibitors is more effective than single treatments in reducing cell viability and colony formation ability in melanoma cells. Together, these findings led to the identification of a novel Hedgehog-GLI-ERK5 axis that regulates melanoma cell growth, and shed light on new functions of ERK5, paving the way for new therapeutic options in melanoma and other neoplasms with active Hedgehog-GLI and ERK5 pathways.

Genistein: A Potent Anti-Breast Cancer Agent.

Genistein is an isoflavonoid present in high quantities in soybeans. Possessing a wide range of bioactives, it is being studied extensively for its tumoricidal effects. Investigations into mechanisms of the anti-cancer activity have revealed many pathways including induction of cell proliferation, suppression of tyrosine kinases, regulation of Hedgehog-Gli1 signaling, modulation of epigenetic activities, seizing of cell cycle and Akt and MEK signaling pathways, among others via which the cancer cell proliferation can be controlled. Notwithstanding, the observed activities have been time- and dose-dependent. In addition, genistein has also shown varying results in women depending on the physiological parameters, such as the early or post-menopausal states.

Beta1-integrin/Hedgehog-Gli1 signaling pathway fuels the diameter-dependent osteoblast differentiation on different TiO2 nanotubes: The optimal-diameter nanotubes for osteoblast differentiation.

Micro/nanotextured topographies (MNTs) can modulate cell-biomaterial interactions mostly by their controllable geometrics. Among them, TiO2 nanotubes, regarded as having a highly controllable nanoscale geometry, have been extensively investigated and applied and significantly affect diameter-dependent cell biological behaviors. In this study, we used five typical MNTs decorated with TiO2 nanotubes with diameters of 30, 50, 70, 100 and 120 nm to explore the optimal nanotube diameter for improving the biofunctional properties and to more deeply understand the underlying mechanisms by which these MNTs affect osteogenic differentiation by revealing the effect of beta1-integrin/Hedgehog-Gli1 signaling on this process. The MNTs affected MG63 osteoblast-like cell spreading, osteogenic gene expression (BMP-2, Runx2 and ALP), mineralization and ALP activity in a diameter-dependent pattern, and the optimal TiO2 nanotube diameter of 70 nm provided the best microenvironment for osteogenic differentiation as well as beta1-integrin/Hedgehog-Gli1 signaling activation. This enhanced osteogenic differentiation by the optimal-diameter TiO2 nanotubes of 70 nm was attenuated via suppression of the beta1-integrin/ Hedgehog-Gli1 signaling, which indicated a significant role of this pathway in mediating the diameter-dependent osteogenic differentiation promotional effect of MNTs with different TiO2 nanotube diameters. These results might provide deeper insights into the signal transduction mechanisms by which different nanoscale geometries influence cellular functions for biomaterial modification and biofunctionalization.

PHF19 activates hedgehog signaling and promotes tumorigenesis in hepatocellular carcinoma

Aberrant activation of Hedgehog-Gli1 signaling and accumulation of Gli1 in hepatocellular carcinoma (HCC) are frequently observed. However, the mechanisms leading to the overactivation of this signaling pathway are not fully understood. In this study, we show that the short isoform of PHD finger protein 19 (PHF19) interacts with β-TrCP, the E3 ligase of Gli1, and that knocking down PHF19 promotes the ubiquitination of Gli1. In a biological function study, PHF19 was found to promote the growth of HCC cells both in liquid culture and in soft agar. Moreover, knocking out PHF19 in a HCC mouse model (MycF/F) using the hydrodynamic method inhibited tumorigenesis and improved survival. Taken together, these results demonstrate that PHF19 promotes the growth of HCC cells by activating the Hedgehog signaling pathway.

WISP-1 induced by mechanical stress contributes to fibrosis and hypertrophy of the ligamentum flavum through Hedgehog-Gli1 signaling

Ongoing chronic fibrosis and hypertrophy of the ligamentum flavum (LF) is an important cause of lumbar spinal canal stenosis (LSCS). Our previous work showed that WNT1-inducible signaling pathway protein 1 (WISP-1) is a critical driver of LF fibrosis. However, the potential mechanism has not been explored. Here, we found that Gli1 was upregulated in hypertrophic LF tissues and required for fibrogenesis in fibroblasts. Moreover, mechanical stretching increased the expression of WISP-1 in LF fibroblasts. Furthermore, WISP-1 induced fibrogenesis in vitro through the Hedgehog-Gli1 pathway. This conclusion was supported by the fact that WISP-1 activated the Hedgehog-Gli1 pathway in LF fibroblasts and that cyclopamine attenuated the effect of WISP-1-induced fibrogenesis. WISP-1 also promoted the transition of fibroblasts into myofibroblasts via the Hedgehog pathway. Importantly, a hypertrophic LF rabbit model induced by mechanical stress also showed pathological changes in fibrosis and elevated expression of WISP-1, Gli1, and α-SMA. Therapeutic administration of cyclopamine reduced collagen expression, fibroblast proliferation, and myofibroblast differentiation and ameliorated fibrosis in the mechanical stress-induced rabbit model. Collectively, our findings show mechanical stress/WISP-1/Hedgehog signaling as a new fibrotic axis contributing to LF hypertrophy and identify Hedgehog signaling as a therapeutic target for the prevention and treatment of LF fibrosis.

WISP-1 Induced by Mechanical Stress Contributes to the Fibrosis and Hypertrophy of Ligamentum Flavum Through the Hedgehog-Gli1 Signaling

Background: The chronic fibrosis and hypertrophy of ligamentum flavum (LF) is an important cause of lumbar spinal canal stenosis (LSCS). Our previous work showed WNT1 inducible signaling pathway protein 1 (WISP-1) is a critical driver of LF fibrosis. However, its potential mechanism has not been explored. Methods: We studied the expression of Hedgehog-related proteins in human LF tissues. Cell viability, cell cycle, apoptosis rate and molecular mechanisms were evaluated in LF cells with lentivirus-mediated knockdown or over-expression of WISP-1 and Gli1. Finally, the molecular mechanism was confirmed in in vivo studies. Findings: The results showed Gli1 was upregulated in hypertrophic LF tissues and required for fibroblast proliferation, apoptosis inhibition and collagen expression in fibroblasts. Moreover, mechanical stretching increased the expression of WISP-1 in LF fibroblasts. Furthermore, WISP-1 induced fibrogenesis in vitro through Hedgehog-Gli1 pathway. This conclusion was supported by the fact that WISP-1 activated Hedgehog-Gli1 pathway in LF fibroblasts and cyclopamine attenuated the effect of WISP-1-induced fibrogenesis. WISP-1 also promoted the transition of fibroblasts into myofibroblasts via Hedgehog pathway. Importantly, hypertrophic LF rabbit model induced by mechanical stress also showed pathological change of fibrosis and more higher expression of WISP-1, Gli1 and ɑ-SMA. Therapeutic administration of cyclopamine reduced collagen expression, fibroblast proliferation, myofibroblast differentiation and ameliorated fibrosis in rabbit model of mechanical stress-induced LF fibrosis. Interpretation: Our study showed the mechanical stress/WISP-1/Hedgehog signaling as a new fibrotic axis contributing to the LF hypertrophy and identified Hedgehog signaling as a therapeutic target for the prevention and treatment of LF fibrosis. Funding Statement: This work was supported by the National Natural Science Foundation of China (Grant No. 81802198) and Natural Science Foundation of Jiangsu Province (Grant No. SBK2019022658). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: An informed consent form was signed by the all patients and the study was approved by the Ethics Committee of Nanjing Medical University (Approval No.20180104).

The anti-lung cancer effect of ethyl acetate extract from Wenxia Formula in vivo via the Hedgehog-Gli1 signaling pathway mediated by cancer associated fibroblasts

IntroductionPrevious research had shown that the ethyl acetate extract from Wenxia Formula (WFEA extract) had significant effects in inhibiting tumor and cancer associated fibroblasts (CAFs). However, the anti-cancer mechanism of the WFEA extract was still unclear. In this study, we aimed to illuminate the possible anti-cancer mechanisms of the WFEA extract.Material and methodsUltra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was applied to analyze and identify the constituents of WFEA extract. The lung cancer xenograft model was conducted to explore the antitumor activity of WFEA extract by measuring tumor volume and weight, HE staining, immunohistochemistry, and immunofluorescence assay. Western blot and qRT-PCR were used to measure the expressions of related proteins and genes in the Hedgehog- Gli1 (Hh-Gli1) signaling pathway.ResultsA total of 15 chemical constituents were identified in the WFEA extract. The xenograft model showed that WFEA extract could inhibit tumor growth and had no significant effect on body weight of mice. In addition, WFEA extract reduced the expression of a-SMA, FAP and N-cadherin in the CAF mediated lung cancer xenograft model and increased the expression of E-cadherin. Western blot and qRT-PCR showed that WFEA extract reduced the expression of related proteins and genes (Smo, Gli1 and Ptch1) in the Hh-Gli1 signaling pathway.ConclusionsWFEA extract had a certain inhibitory effect on lung cancer, and its mechanism may be related to the CAF mediated Hh-Gli1 signaling pathway.

Hedgehog-GLI signalling promotes chemoresistance through the regulation of ABC transporters in colorectal cancer cells

Colorectal cancer (CRC) is a leading cause of cancer death. Chemoresistance is a pivotal feature of cancer cells leading to treatment failure and ATP-binding cassette (ABC) transporters are responsible for the efflux of several molecules, including anticancer drugs. The Hedgehog-GLI (HH-GLI) pathway is a major signalling in CRC, however its role in chemoresistance has not been fully elucidated. Here we show that the HH-GLI pathway favours resistance to 5-fluorouracil and Oxaliplatin in CRC cells. We identified potential GLI1 binding sites in the promoter region of six ABC transporters, namely ABCA2, ABCB1, ABCB4, ABCB7, ABCC2 and ABCG1. Next, we investigated the binding of GLI1 using chromatin immunoprecipitation experiments and we demonstrate that GLI1 transcriptionally regulates the identified ABC transporters. We show that chemoresistant cells express high levels of GLI1 and of the ABC transporters and that GLI1 inhibition disrupts the transporters up-regulation. Moreover, we report that human CRC tumours express high levels of the ABCG1 transporter and that its expression correlates with worse patients’ prognosis. This study identifies a new mechanism where HH-GLI signalling regulates CRC chemoresistance features. Our results indicate that the inhibition of Gli1 regulates the ABC transporters expression and therefore should be considered as a therapeutic option in chemoresistant patients.

Sonic Hedgehog-Gli1 Signaling and Cellular Retinoic Acid Binding Protein 1 Gene Regulation in Motor Neuron Differentiation and Diseases.

Cellular retinoic acid-binding protein 1 (CRABP1) is highly expressed in motor neurons. Degenerated motor neuron-like MN1 cells are engineered by introducing SODG93A or AR-65Q to model degenerated amyotrophic lateral sclerosis (ALS) or spinal bulbar muscular atrophy neurons. Retinoic acid (RA)/sonic hedgehog (Shh)-induced embryonic stem cells differentiation into motor neurons are employed to study up-regulation of Crabp1 by Shh. In SODG93A or AR-65Q MN1 neurons, CRABP1 level is reduced, revealing a correlation of motor neuron degeneration with Crabp1 down-regulation. Up-regulation of Crabp1 by Shh is mediated by glioma-associated oncogene homolog 1 (Gli1) that binds the Gli target sequence in Crabp1′s neuron-specific regulatory region upstream of minimal promoter. Gli1 binding triggers chromatin juxtaposition with minimal promoter, activating transcription. Motor neuron differentiation and Crabp1 up-regulation are both inhibited by blunting Shh with Gli inhibitor GANT61. Expression data mining of ALS and spinal muscular atrophy (SMA) motor neurons shows reduced CRABP1, coincided with reduction in Shh-Gli1 signaling components. This study reports motor neuron degeneration correlated with down-regulation in Crabp1 and Shh-Gli signaling. Shh-Gli up-regulation of Crabp1 involves specific chromatin remodeling. The physiological and pathological implication of this regulatory pathway in motor neuron degeneration is supported by gene expression data of ALS and SMA patients.

GLI3 resides at the intersection of hedgehog and androgen action to promote male sex differentiation.

Urogenital tract abnormalities are among the most common congenital defects in humans. Male urogenital development requires Hedgehog-GLI signaling and testicular hormones, but how these pathways interact is unclear. We found that Gli3XtJ mutant mice exhibit cryptorchidism and hypospadias due to local effects of GLI3 loss and systemic effects of testicular hormone deficiency. Fetal Leydig cells, the sole source of these hormones in developing testis, were reduced in numbers in Gli3XtJ testes, and their functional identity diminished over time. Androgen supplementation partially rescued testicular descent but not hypospadias in Gli3XtJ mutants, decoupling local effects of GLI3 loss from systemic effects of androgen insufficiency. Reintroduction of GLI3 activator (GLI3A) into Gli3XtJ testes restored expression of Hedgehog pathway and steroidogenic genes. Together, our results show a novel function for the activated form of GLI3 that translates Hedgehog signals to reinforce fetal Leydig cell identity and stimulate timely INSL3 and testosterone synthesis in the developing testis. In turn, exquisite timing and concentrations of testosterone are required to work alongside local GLI3 activity to control development of a functionally integrated male urogenital tract.