Sonic Hedgehog/GLI₁ signaling pathway inhibition restricts cell migration and invasion in human gliomas

Fluoride in the Central Nervous System and Its Potential Influence on the Development and Invasiveness of Brain Tumours-A Research Hypothesis

The purpose of this review is to attempt to outline the potential role of fluoride in the pathogenesis of brain tumours, including glioblastoma (GBM). In this paper, we show for the first time that fluoride can potentially affect the generally accepted signalling pathways implicated in the formation and clinical course of GBM. Fluorine compounds easily cross the blood-brain barrier. Enhanced oxidative stress, disruption of multiple cellular pathways, and microglial activation are just a few examples of recent reports on the role of fluoride in the central nervous system (CNS). We sought to present the key mechanisms underlying the development and invasiveness of GBM, as well as evidence on the current state of knowledge about the pleiotropic, direct, or indirect involvement of fluoride in the regulation of these mechanisms in various tissues, including neural and tumour tissue. The effects of fluoride on the human body are still a matter of controversy. However, given the growing incidence of brain tumours, especially in children, and numerous reports on the effects of fluoride on the CNS, it is worth taking a closer look at these mechanisms in the context of brain tumours, including gliomas.

Hedgehog signaling regulates the development and treatment of glioblastoma

Glioblastoma (GBM) is the most common and fatal malignant tumor type of the central nervous system. GBM affects public health and it is important to identify biomarkers to improve diagnosis, reduce drug resistance and improve prognosis (e.g., personalized targeted therapies). Hedgehog (HH) signaling has an important role in embryonic development, tissue regeneration and stem cell renewal. A large amount of evidence indicates that both normative and non-normative HH signals have an important role in GBM. The present study reviewed the role of the HH signaling pathway in the occurrence and progression of GBM. Furthermore, the effectiveness of drugs that target different components of the HH pathway was also examined. The HH pathway has an important role in reversing drug resistance after GBM conventional treatment. The present review highlighted the relevance of HH signaling in GBM and outlined that this pathway has a key role in the occurrence, development and treatment of GBM.

Hedgehog Signaling: Linking Embryonic Lung Development and Asthmatic Airway Remodeling

The development of the embryonic lung demands complex endodermal-mesodermal interactions, which are regulated by a variety of signaling proteins. Hedgehog (Hh) signaling is vital for lung development. It plays a key regulatory role during several morphogenic mechanisms, such as cell growth, differentiation, migration, and persistence of cells. On the other hand, abnormal expression or loss of regulation of Hh signaling leads to airway asthmatic remodeling, which is characterized by cellular matrix modification in the respiratory system, goblet cell hyperplasia, deposition of collagen, epithelial cell apoptosis, proliferation, and activation of fibroblasts. Hh also targets some of the pathogens and seems to have a significant function in tissue repairment and immune-related disorders. Similarly, aberrant Hh signaling expression is critically associated with the etiology of a variety of other airway lung diseases, mainly, bronchial or tissue fibrosis, lung cancer, and pulmonary arterial hypertension, suggesting that controlled regulation of Hh signaling is crucial to retain healthy lung functioning. Moreover, shreds of evidence imply that the Hh signaling pathway links to lung organogenesis and asthmatic airway remodeling. Here, we compiled all up-to-date investigations linked with the role of Hh signaling in the development of lungs as well as the attribution of Hh signaling in impairment of lung expansion, airway remodeling, and immune response. In addition, we included all current investigational and therapeutic approaches to treat airway asthmatic remodeling and immune system pathway diseases.

Tumor Microenvironment in Glioma Invasion

A major malignant trait of gliomas is their remarkable infiltration capacity. When glioma develops, the tumor cells have already reached the distant part. Therefore, complete removal of the glioma is impossible. Recently, research on the involvement of the tumor microenvironment in glioma invasion has advanced. Local hypoxia triggers cell migration as an environmental factor. The transcription factor hypoxia-inducible factor (HIF) -1α, produced in tumor cells under hypoxia, promotes the transcription of various invasion related molecules. The extracellular matrix surrounding tumors is degraded by proteases secreted by tumor cells and simultaneously replaced by an extracellular matrix that promotes infiltration. Astrocytes and microglia become tumor-associated astrocytes and glioma-associated macrophages/microglia, respectively, in relation to tumor cells. These cells also promote glioma invasion. Interactions between glioma cells actively promote infiltration of each other. Surgery, chemotherapy, and radiation therapy transform the microenvironment, allowing glioma cells to invade. These findings indicate that the tumor microenvironment may be a target for glioma invasion. On the other hand, because the living body actively promotes tumor infiltration in response to the tumor, it is necessary to reconsider whether the invasion itself is friend or foe to the brain.

Current insights on extracellular vesicle-mediated glioblastoma progression: Implications in drug resistance and epithelial-mesenchymal transition

BACKGROUND

Glioblastoma multiforme (GBM) is one of the most fatal tumors of the central nervous system with high rate of disease progression, diagnosis, prognosis and low survival rate. Therapeutic approaches that relied on surgical resection and chemotherapy have been unable to curb the disease progression and subsequently leading to increase in incidences of GBM reoccurrence.

SCOPE OF THE REVIEW

In the recent times, membrane-bound extracellular vesicles (EVs) have been observed as one of the key reasons for the uncontrolled growth of GBM. EVs are shown to have the potential to contribute to the disease progression via mediating drug resistance and epithelial-mesenchymal transition. The GBM-derived EVs (GDEVs) with its cargo contents act as the biological trojan horse and lead to disease progression after being received by the recipient target cells. This review article highlights the biophysical, biochemical properties of EVs, its cargo contents and its potential role in the growth and progression of GBM by altering tumour microenvironment.

MAJOR CONCLUSIONS

EVs are being explored for serving as novel disease biomarkers in a variety of cancer types such as adenocarcinoma, pancreatic cancer, color rectal cancer, gliomas and glioblastomas. Improvement in the EV isolation protocols, polymer-based separation techniques and transcriptomics, have made EVs a key diagnostic marker to unravel the progression and early GBM diagnosis. GDEVs role in tumour progression is under extensive investigations.

GENERAL SIGNIFICANCE

Attempts have been also made to discuss and compare the usage of EVs as potential therapeutic targets versus existing therapies targeting drug resistance and EMT.

Anticancer effects of veratramine via the phosphatidylinositol-3-kinase/serine-threonine kinase/mechanistic target of rapamycin and its downstream signaling pathways in human glioblastoma cell lines

AIMS

Antitumor effects of veratramine in prostate and liver cancers has been investigated, but it is still unclear whether veratramine can be used as an effective therapeutic agent for glioma. The aim of this study was to evaluate the potential pharmacological mechanism of veratramine in glioma.

MAIN METHODS

Using four types of human glioblastoma cell lines, including A172, HS-683, T98G, and U-373-MG the dose-dependent antitumor effect of veratramine was evaluated. The cytotoxicity and cell proliferation were examined by CCK-8, and cell proliferation was further confirmed by anchorage-independent colony formation assay. The cell cycle distribution and apoptotic rate was assessed by flow cytometry, and apoptosis was further evaluated by apoptosis assay. The migration and invasiveness capacity were analyzed by using transwell. Protein and mRNA levels of related factors were determined by western blotting and RT-qPCR, respectively.

KEY FINDINGS

Veratramine markedly induced apoptosis, suppressed the cell proliferation via the cell cycle G₀/G₁ phase arrest, and reduced the capacity for the migration and invasion in human glioblastoma multiforme cell lines. Moreover, veratramine was sufficient to affect the phosphatidylinositol-3-kinase/serine-threonine kinase/mechanistic target of rapamycin signaling pathway and its downstream Mdm2/p53/p21 pathway in human glioblastoma cell lines.

SIGNIFICANCE

Antitumor effects of veratramine in suppression of glioma progression was mediated by the regulation of PI3K/Akt/mTOR and Mdm2/p53/p21 signaling pathway.

Naringenin attenuates cell viability and migration of C6 glioblastoma cell line: a possible role of hedgehog signaling pathway

OBJECTIVE

Gliomas are the most prevalent type of malignant primary brain tumors. Despite the availability of several treatment modalities, these tumors have poor prognostic features. Aberrant Hedgehog (Hh) signaling has been found to be implicated in the development of numerous malignancies including gliomas. Naringenin appears to have anti-proliferative and anti-cancer properties. However, there is no report describing its effects via the Hh signaling pathway on the C6 glioblastoma cell line. The current study was set to examine the anti-cancer effects of naringenin on C6 cells in order to determine the effect of this compound on the Hh signaling pathway.

METHODS

The anti-proliferative and apoptotic effects of naringenin against C6 and 3T3 fibroblast cells were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and annexin-V/PI dual staining assay, respectively. The effect of naringenin on the migration of C6 cells was evaluated by the migration scratch assay. To assess the anti-cancer effect of naringenin on the Hh signaling pathway, the expression of Gli-1, Smo, and Sufu at protein levels in C6 cells was analyzed using western blotting.

RESULTS

The obtained data indicated that naringenin exerted higher cytotoxicity against C6 cells (IC50 value of 114 ± 3.4 µg/mL) than normal 3T3 fibroblasts (IC50 value of 290 ± 7 µg/mL). Naringenin (114 µg/mL) also induced stronger apoptotic effects on C6 cells than 3T3 cells after 24 h of incubation. Furthermore, naringenin at a concentration of 114 µg/mL and a lower concentration of 60 µg/mL inhibited the migration of the C6 cell line. In addition, naringenin at a concentration of 114 µg/mL significantly decreased the expression of Gli-1 and Smo and elevated the expression of Sufu at the protein level in the C6 cell line.

CONCLUSION

These data represent that naringenin may have a potential effect on the management of the proliferation and metastasis of malignant gliomas by inhibiting the Hh signaling pathway.

Expression of activator proteins of SHH/GLI and PI3K/Akt/mTORC1 signaling pathways in human gliomas is associated with high grade tumors

Recent findings have demonstrated a synergic crosstalk between SHH/GLI and PI3K/Akt/mTORC1 signaling in glioblastoma progression cells in vitro and in tumors in mice, but it is not known if this also occurs in human gliomas. We then aimed to investigate the expression of key proteins of these pathways in different human gliomas. The expression of PTEN, phospho-Akt (Ser473), phospho-S6K1 (Thr389), SHH, GLI1, GLI2 and GLI3 was assessed by immunohistochemistry in gliomas and in control brain tissues. The pattern of expression of each protein was established according to glioma type, glioma grade and to cell type; the relative expression of each protein was used to perform statistical analyses. We found that the expression of proteins of both signaling pathways differs between normal brain and glioma tissues. For instance, normal astrocytes had a different protein expression pattern compared with reactive and tumoral astrocytes. Interestingly, we detected a recurrent pattern of expression of GLI3 in oligodendrocytes and of phospho-S6K1 in mitotic neoplastic cells. We also identified differences of cell signaling according to glioma type: oligodendrogliomas and ependymomas are related with the expression of SHH/GLI proteins. Finally, we detected that high grade gliomas statistically correlate with the expression of GLI1 and GLI2, and that GLI1, GLI2, phospho-Akt and phospho-S6K1 are more expressed in patients with less survival, suggesting that activation of these cell signaling influences glioma outcome and patient survival. In summary, our results show that proteins of PI3K/Akt/mTORC1 and SHH/GLI pathways are differentially expressed in human gliomas according to tumor type and grade, and suggest that the activation of these signaling networks is associated with glioma progression.

Drugging the 'undruggable'. Therapeutic targeting of protein-DNA interactions with the use of computer-aided drug discovery methods

Transcription factors (TFs) act as major oncodrivers in many cancers and are frequently regarded as high-value therapeutic targets. The functionality of TFs relies on direct protein-DNA interactions, which are notoriously difficult to target with small molecules. However, this prior view of the 'undruggability' of protein-DNA interfaces has shifted substantially in recent years, in part because of significant advances in computer-aided drug discovery (CADD). In this review, we highlight recent examples of successful CADD campaigns resulting in drug candidates that directly interfere with protein-DNA interactions of several key cancer TFs, including androgen receptor (AR), ETS-related gene (ERG), MYC, thymocyte selection-associated high mobility group box protein (TOX), topoisomerase II (TOP2), and signal transducer and activator of transcription 3 (STAT3). Importantly, these findings open novel and compelling avenues for therapeutic targeting of over 1600 human TFs implicated in many conditions including and beyond cancer.

Modulation of the chemokine/chemokine receptor axis as a novel approach for glioma therapy

Chemokines are a large subfamily of cytokines known for their ability to facilitate cell migration, most notably leukocytes, throughout the body. Chemokines are necessary for a functioning immune system in both health and disease and have received considerable attention for their roles in orchestrating temporal-spatial regulation of immune cell populations in cancer. Gliomas comprise a group of common central nervous system (CNS) primary tumors that are extremely challenging to treat. Immunotherapy approaches for highly malignant brain tumors offer an exciting new avenue for therapeutic intervention but so far, have seen limited successful clinical outcomes. Herein we focus on important chemokine/chemokine receptor systems in the regulation of pro- and anti-tumor mechanisms, highlighting potential therapeutic advantages of modulating these systems in malignant gliomas and other cancers.

Nano drug delivery system reconstruct tumour vasculature for the tumour vascular normalisation

The abnormal structure and function of blood vessels in the TME are obvious characteristics of the tumour. Abnormal blood vessels with high leakage support the occurrence of malignant tumours and increase the possibility of tumour cell invasion and metastasis. The formation of abnormal vascular also enhances immunosuppression and prevents the delivery of chemotherapy drugs to deeper tumours. Therefore, the normalisation of tumour blood vessels is a very promising approach to improve anti-tumour efficacy, aiming to restore the structural integrity of vessels and improve drug delivery efficiency and anti-tumour immunity. In this review, we have summarised strategies to improve cancer treatment that via nano drug delivery technology regulates the normalisation of tumour blood vessels. The treatment strategies related to the structure and function of tumour blood vessels such as angiogenesis factors, tumour-associated macrophages, tumour vascular endothelial cells, tumour-associated fibroblasts and immune checkpoints in the TME were mainly discussed. The normalisation of tumour blood vessels presents new opportunities and challenges for the more efficient delivery of nanoparticles to tumour tissues and cells and an innovative combination of treatments for cancer.

Hedgehog Signaling: Implications in Cancers and Viral Infections

The hedgehog (SHH) signaling pathway is primarily involved in embryonic gut development, smooth muscle differentiation, cell proliferation, adult tissue homeostasis, tissue repair following injury, and tissue polarity during the development of vertebrate and invertebrate organisms. GLIoma-associated oncogene homolog (GLI) family of zinc-finger transcription factors and smoothened (SMO) are the signal transducers of the SHH pathway. Both SHH ligand-dependent and independent mechanisms activate GLI proteins. Various transcriptional mechanisms, posttranslational modifications (phosphorylation, ubiquitination, proteolytic processing, SUMOylation, and acetylation), and nuclear-cytoplasmic shuttling control the activity of SHH signaling pathway proteins. The dysregulated SHH pathway is associated with bone and soft tissue sarcomas, GLIomas, medulloblastomas, leukemias, and tumors of breast, lung, skin, prostate, brain, gastric, and pancreas. While extensively studied in development and sarcomas, GLI family proteins play an essential role in many host-pathogen interactions, including bacterial and viral infections and their associated cancers. Viruses hijack host GLI family transcription factors and their downstream signaling cascades to enhance the viral gene transcription required for replication and pathogenesis. In this review, we discuss a distinct role(s) of GLI proteins in the process of tumorigenesis and host-pathogen interactions in the context of viral infection-associated malignancies and cancers due to other causes. Here, we emphasize the potential of the Hedgehog (HH) pathway targeting as a potential anti-cancer therapeutic approach, which in the future could also be tested in infection-associated fatalities.

Epigenetics of glioblastoma multiforme: From molecular mechanisms to therapeutic approaches

Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.

LINC00294 induced by GRP78 promotes cervical cancer development by promoting cell cycle transition

Cervical cancer is one of the most common gynecological malignancies, and it has become a crucial public health problem. In the present study, the expression profiles of cervical cancer and normal cervical tissues were downloaded from the Gene Expression Omnibus and The Cancer Genome Atlas databases. Subsequently, the dysregulated long non-coding RNAs (lncRNAs) in cervical cancer were identified using R software Differentially expressed lncRNAs in cervical cancer that were associated with glucose-regulated protein 78 (GRP78) were screened out and the results demonstrated that eight lncRNAs were strongly positively correlated with GRP78. In order to confirm the relationship between GRP78 and candidate lncRNAs, GRP78 small interfering RNA (siRNA) was transfected into HeLa cells. The target lncRNAs that were regulated by GRP78 were then identified by reverse transcription-quantitative PCR and it was revealed that LINC00294 was significantly downregulated following GRP78-knockdown. Subsequently, Gene Set Enrichment Analysis demonstrated that LINC00294 was mainly enriched in regulating the cell cycle and the Hedgehog pathway. Following transfection of HeLa and SiHa cells with LINC00294 siRNA, the cell cycle was arrested at the G0/G1 phase. Western blotting suggested that LINC00294-knockdown downregulated the expression of cell cycle-associated factors (cyclin D, cyclin E and cyclin Dependent kinase 4) and upregulated cell cycle inhibitory factors (p16 and p21). The Hedgehog pathway was inhibited following knockdown of LINC00294 in HeLa and SiHa cells. In summary, LINC00294 induced by GRP78 promoted the progression of cervical cancer by regulating the cell cycle via Hedgehog pathway.

Novel insights into astrocyte-mediated signaling of proliferation, invasion and tumor immune microenvironment in glioblastoma

Glioblastoma (GBM) continues to be the most aggressive cancer of the brain. The dismal prognosis is largely attributed to the microenvironment surrounding tumor cells. Astrocytes, the main component of the GBM microenvironment, play several fundamental physiological roles in the central nervous system. During the development of GBM, tumor-associated astrocytes (TAAs) directly contact GBM cells, which activate astrocytes to form reactive astrocytes, facilitating tumor progression, proliferation and migration through multiple well-understood signaling pathways. Notably, TAAs also influence GBM cell behaviors via suppressing immune responses and enhancing the chemoradiotherapy resistance of tumor cells. These new activities are closely linked with the treatment and prognosis of GBM. In this review, we discuss recent advances regarding new functions of reactive astrocytes, including TAA-cancer cell interactions, mechanisms involved in immunosuppressive regulation, and chemoradiotherapy resistance. It is expected that these updated experimental or clinical studies of TAAs may provide a promising approach for GBM treatment in the near future.

Ginsenoside Rh2 activates α-catenin phosphorylation to inhibit lung cancer cell proliferation and invasion

The efficacy of ginsenoside Rh2 (Rh2) in cancer therapy has been reported; however, its function in lung cancer remains unknown. To analyze the role of Rh2 in the inhibition of lung cancer cell proliferation in the present study, protein expression levels of E-cadherin, vimentin, β-catenin, Smo, Gli1, and α-catenin were assessed by western blotting, whilst mRNA expression levels of TCF7 FZD8, Smo, Gli1, Gli2, and Gli3 were determined by reverse transcription-quantitative PCR in the A549 cell line. Phosphorylation sites were detected by proteomic methods and cell proliferation was analyzed by MTT assay. The present study revealed that Rh2 treatment significantly inhibited cell proliferation. Western blotting indicated that the expression levels of E-cadherin were increased and vimentin was downregulated in Rh2-treated cells compared with control cells. Treatment of A549 cells with Rh2 suppressed phosphorylation of five distinct proteins and increased phosphorylation of nine proteins. Among them, the phosphorylation of α-catenin at S641 was significantly induced. Rh2 treatment suppressed the expression levels of key genes involved in Wnt (Wnt3, transcription factor 7 and frizzled class receptor 8) and hedgehog [smoothened, frizzled class receptor (Smo), GLI family zinc finger (Gli)1, Gli2, and Gli3] signaling. Immunoblotting results indicated that β-catenin, Smo and Gli1 protein expression levels were also suppressed by treatment with Rh2 compared with control treatment. Expression of α-catenin S641D, a phosphomimetic form of α-catenin, inhibited the accumulation of β-catenin and Gli1 and inhibited cell proliferation and invasion. Furthermore, knockdown of β-catenin (CTNNB1) or Gli1 with specific small interfering RNAs inhibited cell proliferation, whereas overexpression of these genes had an opposite effect. Additionally, overexpression of β-catenin or Gli1 activated cell proliferation, even in the presence of Rh2, suggesting that Rh2 affects A549 cell proliferation through inhibition of Wnt and hedgehog signaling by phosphorylation of α-catenin at S641. Together, these data suggested that Rh2 treatment may inhibit the proliferation of A549 lung cancer cells. Further exploration of the underlying mechanism by which Rh2 inhibits cell proliferation is warranted.

Hedgehog signaling pathway inhibitors: an updated patent review (2015-present)

Introduction: Hedgehog (Hh) signaling plays a pivotal role in tissue development and stemness, and its deregulation is found in many different tumors. Several efforts have been devoted to discovery of Hh inhibitors, including three drugs approved by the Food and Drug Administration (FDA), targeting the upstream receptor smoothened (SMO). However, SMO mutations or SMO-independent Hh pathway activation raise the need for novel Hh inhibitors.Areas covered: This review describes Hh inhibitors with anticancer potential patented in the period 2015-present.Expert opinion: Despite the initial enthusiasm in SMO antagonists, drug-resistant mutations, and SMO-independent Hh activation limited their clinical application. A growing number of therapeutic strategies are currently focusing on downstream Hh effectors (i.e. glioma-associate oncogenes (GLI) proteins) or other signaling pathways related to Hh, in addition to drug repositioning. Given the heterogenic nature of cancers, a terrific clinical impact is expected by multi-targeting approaches able to modulate simultaneously SMO and GLI, and/or additional targets that act as regulators of Hh signaling. It is expected that these alternative strategies might be investigated in clinical trials in the next years against a wide variety of tumor types, and that they provide improved outcomes compared to current SMO antagonists or other single-agent anticancer drugs.

Current Understanding of Nasal Epithelial Cell Mis-Differentiation

The functional role of the respiratory epithelium is to generate a physical barrier. In addition, the epithelium supports the innate and acquired immune system through various cytokines and chemokines. However, epithelial cells are also involved in the pathogenesis of various respiratory diseases, some of which are mediated by increased permeability of the mucosal membrane or disturbed mucociliary transport. In addition, it has been shown that epithelial cells are involved in the development of inflammatory respiratory diseases. The following review article focuses on the aspects of epithelial mis-differentiation, in particular with respect to nasal mucosal barrier function, epithelial immunogenicity, nasal epithelial-mesenchymal transition and nasal microbiome.

Molecular and Clinical Insights into the Invasive Capacity of Glioblastoma Cells

The invasive capacity of GBM is one of the key tumoral features associated with treatment resistance, recurrence, and poor overall survival. The molecular machinery underlying GBM invasiveness comprises an intricate network of signaling pathways and interactions with the extracellular matrix and host cells. Among them, PI3k/Akt, Wnt, Hedgehog, and NFkB play a crucial role in the cellular processes related to invasion. A better understanding of these pathways could potentially help in developing new therapeutic approaches with better outcomes. Nevertheless, despite significant advances made over the last decade on these molecular and cellular mechanisms, they have not been translated into the clinical practice. Moreover, targeting the infiltrative tumor and its significance regarding outcome is still a major clinical challenge. For instance, the pre- and intraoperative methods used to identify the infiltrative tumor are limited when trying to accurately define the tumor boundaries and the burden of tumor cells in the infiltrated parenchyma. Besides, the impact of treating the infiltrative tumor remains unclear. Here we aim to highlight the molecular and clinical hallmarks of invasion in GBM.

Glutamate Receptors and Glioblastoma Multiforme: An Old "Route" for New Perspectives

Glioblastoma multiforme (GBM) is the most aggressive malignant tumor of the central nervous system, with poor survival in both treated and untreated patients. Recent studies began to explain the molecular pathway, comprising the dynamic structural and mechanical changes involved in GBM. In this context, some studies showed that the human glioblastoma cells release high levels of glutamate, which regulates the proliferation and survival of neuronal progenitor cells. Considering that cancer cells possess properties in common with neural progenitor cells, it is likely that the functions of glutamate receptors may affect the growth of cancer cells and, therefore, open the road to new and more targeted therapies.

A novel, liver-specific long noncoding RNA LINC01093 suppresses HCC progression by interaction with IGF2BP1 to facilitate decay of GLI1 mRNA

Long noncoding RNAs (lncRNAs) are implicated as novel drivers in hepatocellular carcinoma (HCC), but the underlying mechanisms of this relationship with hepatocarcinogenesis are unknown. We report a novel, liver-specific lncRNA LINC01093 that shows significant downregulation in HCC tissues. LINC01093 expression is inversely correlated with cancer embolus and HCC TNM stage and as a prognostic predictor for HCC patients. LINC01093 overexpression significantly suppresses HCC cell proliferation and metastasis in vitro and in vivo. Conversely, its knockdown promotes HCC progression. Mechanistic analyses indicate that LINC01093 directly binds insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), interfering with interaction between IGF2BP1 and glioma-associated oncogene homolog 1 (GLI1) mRNA. The result is degradation of GLI1 mRNA, further affecting expression of GLI1 downstream molecules involved in HCC progression. The liver-enriched lncRNA LINC01093 is a promising prognostic indicator for HCC patients, and the newly identified LINC01093-IGF2BP1-GLI1 axis shows potential for therapeutic targets in HCC.

Abnormal activity of transcription factors gli in high-grade gliomas

Malignant transformation is associated with loss of cell differentiation, anaplasia. Transcription factors gli, required for embryonic development, may be involved in this process. We studied the activity of transcription factors gli in high-grade gliomas and their role in maintenance of stem cell state and glioma cell survival. 20 glioma cell lines and a sample of a normal adult brain tissue were used in the present study. We found the expression of gli target genes, including GLI1 and FOXM1, in all tested glioma cell lines, but not in the normal tissue. Interestingly, the expression of gli target genes in some glioma cell lines was observed together with a high level of their transcriptional repressor, Gli3R. Knockdown of GLI3 in one of these lines resulted in decrease of gli target gene expression. These data suggest that Gli3R does not prevent the gli target genes transcription, and gli3 acts in glioma cells more as an activator, than a repressor of transcription. We observed that gli regulated the expression of such genes, as SOX2 or OCT4 that maintain stem cell state, and TET1, involving in DNA demethylation. Treatment with GANT61 or siRNA against GLI1, GLI2, or GLI3 could result in complete glioma cell death, while cyclopamine had a weaker and line-specific effect on glioma cell survival. Thus, the gli transcription factors are abnormally active in high-grade gliomas, regulate expression of genes, maintaining the stem cell state, and contribute to glioma cell survival.

Wnt3a-regulated TCF4/β-catenin complex directly activates the key Hedgehog signalling genes Smo and Gli1

The Wnt and Hedgehog signalling pathways serve key roles in diverse developmental processes. However, the molecular associations between these two signalling pathways remains unclear. Previous transcriptome studies on human foreskin fibroblasts have indicated that Wnt signalling activation induces the expression of key Hedgehog signalling genes, including smoothened, frizzled class receptor (Smo) and GLI family zinc finger 1 (Gli1). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) results revealed that Wnt3a treatment induced the expression of the key Hedgehog signalling genes, including Smo, patched (PTCH), Gli1, Gli2 and Gli3. In addition, western blot analyses demonstrated that Wnt3a treatment resulted in the accumulation of cellular Smo and Gli proteins. Furthermore, promoter sequence analysis revealed that the putative β-catenin/T-cell factor (TCF)-4 complex binding motifs (^T/_A^C/_GAAAG) were located within 1.5 kb of the Smo and Gli1 promoters. Results of the chromatin immunoprecipitation experiments and yeast-one hybrid assays revealed that TCF4 directly binds to the Smo and Gli1 promoters, with two binding sites for Smo and a single binding site for Gli1. Further analysis showed that the β-catenin/TCF4 complex binds to the Smo and Gli1 promoters. To investigate the functions of TCF4 and β-catenin in transcriptional regulation of Smo and Gli1, TCF4 and β-catenin were transiently expressed in fibroblast cells. RT-qPCR results demonstrated that overexpression of TCF4 and β-catenin induced the expression of Smo and Gli1. In addition, small interfering RNA-mediated suppression of β-catenin resulted in the downregulation of Smo and Gli1 expression levels, even under Wnt3a treatment. Suppression of β-catenin and Gli1 expression inhibited cell proliferation. Taken together, the results of the present study suggested that the β-catenin/TCF4 complex directly activates Smo and Gli1 by binding to their promoters, which in turn controls cell proliferation in human fibroblasts.

Investigating the role of Hedgehog/GLI1 signaling in glioblastoma cell response to temozolomide

Resistance to chemotherapy substantially hinders successful glioblastoma (GBM) treatment, contributing to an almost 100% mortality rate. Resistance to the frontline chemotherapy, temozolomide (TMZ), arises from numerous signaling pathways that are deregulated in GBM, including Hedgehog (Hh) signaling. Here, we investigate suppression of Hh signaling as an adjuvant to TMZ using U87-MG and T98G cell lines as in vitro models of GBM. We found that silencing GLI1 with siRNA reduces cell metabolic activity by up to 30% in combination with TMZ and reduces multidrug efflux activity by 2.5-fold. Additionally, pharmacological GLI inhibition modulates nuclear p53 levels and decreases MGMT expression in combination with TMZ. While we surprisingly found that silencing GLI1 does not induce apoptosis in the absence of TMZ co-treatment, we discovered silencing GLI1 without TMZ co-treatment induces senescence as evidenced by a significant 2.3-fold increase in senescence associated β-galactosidase staining, and this occurs in a loss of PTEN-dependent manner. Finally, we show that GLI inhibition increases apoptosis in glioma stem-like cells by up to 6.8-fold in combination with TMZ, and this reduces the size and number of neurospheres grown from glioma stem-like cells. In aggregate, our data warrant the continued investigation of Hh pathway inhibitors as adjuvants to TMZ chemotherapy and highlight the importance of identifying signaling pathways that determine whether co-treatment will be successful.

Sonic hedgehog-c-Jun N-terminal kinase-zinc finger protein Gli1 signaling protects against high glucose concentration-induced reactive oxygen species generation in human fibroblasts

Diabetes mellitus (DM) complications affect patients and cause varying damage. Skin ulcers exhibit difficulties in wound healing, and the regulatory basis for this remains unclear. High glucose concentration (HG) was utilized to mimic DM in cultured cells. Reverse transcription-quantitative polymerase chain reaction, western blotting and fluorescence dye analyses were performed to analyze the effects of hedgehog signaling in regulation of HG or diabetes in fibroblasts. HG-stress suppressed hedgehog-signaling gene expression, whereas the apoptosis and inflammatory response markers, Caspase-3 and plasminogen activator inhibitor-1 (PAI1), respectively, were induced. In addition, HG-stress inhibited the fibroblast proliferation rate. In parallel, treatment with Sonic hedgehog (Shh), an activator of hedgehog signaling, together with HG eliminated effects of HG on expression of hedgehog-signaling genes, Caspase-3 and PAI1, and rescued the cell proliferation rate in fibroblasts. In addition, Shh application activated c-Jun N-terminal kinase (JNK), which was inhibited by HG stress. sp600125, a JNK specific inhibitor, treatment inhibited the effect of Shh on fibroblast proliferation and hedgehog-signaling marker gene expression. Furthermore, zinc finger protein Gli1 (Gli1) overexpression partially eliminated the effect of HG and sp600125 on fibroblast proliferation, and reduced HG-induced ROS generation in fibroblasts. Together, these results indicate that HG stress inhibits hedgehog signaling, and Shh-JNK-Gli1 pathway positively regulates HG-induced damage on fibroblasts.

Hedgehog/Gli1 signaling pathway regulates MGMT expression and chemoresistance to temozolomide in human glioblastoma

Background

Chemoresistance of glioblastoma (GBM) is a feature of this devastating disease. This study is to determine the relationship between Hedgehog (HH)/Gli1 signaling pathway and chemoresistance to temozolomide (TMZ) in human GBM.

Methods

We analyzed Gli1 nuclear staining and O⁶-methylguanine DNA methyltransferase (MGMT) expression in 48 cases of primary GBM tissues by immunohistochemistry. Quantitative PCR, western blot, methylation-specific PCR, cell proliferation and apoptosis assay were used to investigate changes of MGMT expression and chemosensitivity to TMZ after manipulating HH/Gli1 signaling activity in A172 and U251 GBM cell lines. Chromatin immunoprecipitation assay was utilized to identify potential Gli1 potential binding sites in MGMT gene promoter region. We established GBM xenografts using U251 cells to assess whether inhibiting HH/Gli1 signaling activity restored chemosensitivity to TMZ.

Results

O⁶-Methylguanine DNA methyltransferase-positive GBM tissues had a significantly higher rate of Gli1 nuclear staining than MGMT-negative ones (67.7% vs. 32.3%, p = 0.0159). Activation of HH/Gli1 signaling by pcDNA3.1-Gli1 cell transfection in A172 cells led to increased MGMT expression and enhanced resistance to TMZ treatment. Inhibition of the HH/Gli1 signaling by cyclopamine in U251 cells resulted in decreased MGMT expression and increased sensitivity to TMZ treatment. Both ways altered MGMT levels without changing the MGMT promoter methylation. The potential binding site of Gli1 in the MGMT gene promoter region was located at - 411 to - 403 bp upstream the transcriptional start site. The in vivo study revealed a synergistic effect on tumor growth inhibition with the combined administration of cyclopamine and TMZ.

Conclusions

This study shows that HH/Gli1 signaling pathway regulates MGMT expression and chemoresistance to TMZ in human GBM independent from MGMT promoter methylation status, which offers a potential target to restore chemosensitivity to TMZ in a fraction of GBM with high MGMT expression.

Nucleolar and spindle associated protein 1 promotes the aggressiveness of astrocytoma by activating the Hedgehog signaling pathway

BACKGROUND

The prognosis of human astrocytoma is poor, and the molecular alterations underlying its pathogenesis still needed to be elucidated. Nucleolar and spindle associated protein 1 (NUSAP1) was observed in several types of cancers, but its role in astrocytoma remained unknown.

METHODS

The expression of NUSAP1 in astrocytoma cell lines and tissues were measured with western blotting and Real-Time PCR. Two hundred and twenty-one astrocytoma tissue samples were analyzed by immunochemistry to demonstrate the correlation between the NUSAP1 expression and clinicopathological characteristics. 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay, colony formation, transwell matrix penetration assay, wound healing assay and anchorage-independent growth assay were used to investigate the biological effect of NUSAP1 in astrocytoma. An intracranial brain xenograft tumor model was used to confirm the oncogenic role of NUSAP1 in human astrocytoma. Luciferase reporter assay was used to investigate the effect of NUSAP1 on Hedgehog signaling pathway.

RESULTS

NUSAP1 was markedly overexpressed in astrocytoma cell lines and tissues compared with normal astrocytes and brain tissues. NUSAP1 was found to be overexpressed in 152 of 221 (68.78%) astrocytoma tissues, and was significantly correlated to poor survival. Further, ectopic expression or knockdown of NUSAP1 significantly promoted or inhibited, respectively, the invasive ability of astrocytoma cells. Moreover, intracranial xenografts of astrocytoma cells engineered to express NUSAP1 were highly invasive compared with the parental cells. With regard to its molecular mechanism, upregulation of NUSAP1 in astrocytoma cells promoted the nuclear translocation of GLI family zinc finger 1 (GLI1) and upregulated the downstream genes of the Hedgehog pathway.

CONCLUSION

These findings indicate that NUSAP1 contributes to the progression of astrocytoma by enhancing tumor cell invasiveness via activation of the Hedgehog signaling pathway, and that NUSAP1 might be a potential prognostic biomarker as well as a target in astrocytoma.

EMT- and MET-related processes in nonepithelial tumors: importance for disease progression, prognosis, and therapeutic opportunities

The epithelial-to mesenchymal (EMT) process is increasingly recognized for playing a key role in the progression, dissemination, and therapy resistance of epithelial tumors. Accumulating evidence suggests that EMT inducers also lead to a gain in mesenchymal properties and promote malignancy of nonepithelial tumors. In this review, we present and discuss current findings, illustrating the importance of EMT inducers in tumors originating from nonepithelial/mesenchymal tissues, including brain tumors, hematopoietic malignancies, and sarcomas. Among these tumors, the involvement of mesenchymal transition has been most extensively investigated in glioblastoma, providing proof for cell autonomous and microenvironment-derived stimuli that provoke EMT-like processes that regulate stem cell, invasive, and immunogenic properties as well as therapy resistance. The involvement of prominent EMT transcription factor families, such as TWIST, SNAI, and ZEB, in promoting therapy resistance and tumor aggressiveness has also been reported in lymphomas, leukemias, and sarcomas. A reverse process, resembling mesenchymal-to-epithelial transition (MET), seems particularly relevant for sarcomas, where (partial) epithelial differentiation is linked to less aggressive tumors and a better patient prognosis. Overall, a hybrid model in which more stable epithelial and mesenchymal intermediates exist likely extends to the biology of tumors originating from sources other than the epithelium. Deeper investigation and understanding of the EMT/MET machinery in nonepithelial tumors will shed light on the pathogenesis of these tumors, potentially paving the way toward the identification of clinically relevant biomarkers for prognosis and future therapeutic targets.

Negative prognostic effect of low nuclear GLI1 expression in glioblastomas

The hedgehog signaling plays supportive roles in various aspects of tumorigenesis. Increased expression of the key component, GLI1, has been shown to correlate with poor prognosis in many types of cancers. We aimed to investigate the effect of GLI1 expression in glioblastoma focusing on the nuclear localization. Immunohistochemistry for GLI1, GLI2, PTCH1, SMO, and SHH were done in 140 glioblastoma tissues, and the staining was graded. For GLI1, nuclear and cytoplasmic expression was separately assessed. No significant correlation was found between clinicopathologic parameters and expression grades of the five proteins. Low nuclear GLI1 expression was associated with a worse progression-free survival while overall survival was not significantly affected. In contrast, cytoplasmic GLI1 expression did not have a prognostic effect. PTCH1 expression correlated with nuclear GLI1 expression without exerting a significant prognostic effect. Analysis of the TCGA-glioblastoma dataset revealed that low GLI1 mRNA level also correlated with a poor prognosis for both overall and progression-free survival. The adverse effect of low nuclear GLI1 expression in glioblastomas is in contrast with the negative prognostic effect of high GLI1 expression reported in non-cranial malignancies. The relative impact of hedgehog signaling among other oncogenic pathways in the brain may be responsible for the difference. The different implication of GLI1 expression in glioblastomas needs to be considered in studies of hedgehog signaling-targeted therapy.

Hedgehog signaling contributes to basic fibroblast growth factor-regulated fibroblast migration

Fibroblast migration is a central process in skin wound healing, which requires the coordination of several types of growth factors. bFGF, a well-known fibroblast growth factor (FGF), is able to accelerate fibroblast migration; however, the underlying mechanism of bFGF regulation fibroblast migration remains unclear. Through the RNA-seq analysis, we had identified that the hedgehog (Hh) canonical pathway genes including Smoothened (Smo) and Gli1, were regulated by bFGF. Further analysis revealed that activation of the Hh pathway via up-regulation of Smo promoted fibroblast migration, invasion, and skin wound healing, but which significantly reduced by GANT61, a selective antagonist of Gli1/Gli2. Western blot analyses and siRNA transfection assays demonstrated that Smo acted upstream of phosphoinositide 3-kinase (PI3K)-c-Jun N-terminal kinase (JNK)-β-catenin to promote cell migration. Moreover, RNA-seq and qRT-PCR analyses revealed that Hh pathway genes including Smo and Gli1 were under control of β-catenin, suggesting that β-catenin turn feedback activates Hh signaling. Taken together, our analyses identified a new bFGF-regulating mechanism by which Hh signaling regulates human fibroblast migration, and the data presented here opens a new avenue for the wound healing therapy.

Aberrant expression of Sonic hedgehog signaling in Peutz-Jeghers syndrome

The SHH signaling pathway is critical for gastrointestinal development and organic patterning, and dysregulation of SHH pathway molecules has been detected in multiple gastrointestinal neoplasms. This study investigated the role of the SHH signaling pathway in PJS. Expression of SHH, PTCH, and GLI1 was examined by real-time PCR and immunohistochemistry in 20 normal tissues and 75 colorectal lesions (25 PJPs, 25 adenomas, and 25 adenocarcinomas). Expression of SHH, PTCH, and GLI1 mRNA was higher in PJPs than in normal tissue (P < .05) and gradually increased along the PJP-adenoma-adenocarcinoma sequence (P < .05). Immunostaining indicated that SHH expression was present in 60% of PJPs, 72% of adenomas, and 84% of carcinomas, whereas 68% of PJPs, 72% of adenomas, and 88% of carcinomas exhibited cytoplasmic expression of PTCH. Moreover, high GLI1 expression was detected in 56% of PJPs, 64% of adenomas, and 80% of carcinomas; and high nuclear expression of GLI1 was observed in 8 adenomas with atypia and 15 carcinomas. Increased SHH, PTCH, and GLI1 protein correlated positively with tumor grade (P = .012, P = .003, and P = .007, respectively), tumor depth (P = .024, P = .007, and P = .01), and lymph node metastasis (P = .05, P = .015, and P = .005). This study identified aberrant expression of SHH pathway molecules in PJS, and the findings may supply a novel mechanism for the development of PJ polyps.

Multi-targeting Peptide-Functionalized Nanoparticles Recognized Vasculogenic Mimicry, Tumor Neovasculature, and Glioma Cells for Enhanced Anti-glioma Therapy

Chemotherapy failure of glioma, the most aggressive and devastating cancer, might be ascribed to the physiologic barriers of the tumor mainly including heterogeneous tumor perfusion and vascular permeability, which result in a limited penetration of chemotherapeutics. Besides, the vasculogenic mimicry (VM) channels, which are highly resistant to anti-angiogenic therapy and serve as a complement of angiogenesis, were abound in glioma and always associated with tumor recurrence. In order to enhance the therapy effect of anti-glioma, we developed a PEG-PLA-based nanodrug delivery system (nanoparticles, NP) in this study and modified its surface with CK peptide, which was composed of a human sonic hedgehog (SHH) targeting peptide (CVNHPAFAC) and a KDR targeting peptide (K237) through a GYG linker, for facilitating efficient VM channels, tumor neovasculature, and glioma cells multi-targeting delivery of paclitaxel. In vitro cellular assay showed that CK-NP-PTX not only exhibited the strongest antiproliferation effect on U87MG cells and HUVEC cells but also resulted in the most efficient destruction of VM channels when compared with CVNHPAFAC-NP, K237-NP, and the unmodified ones. Besides, CK-NP accumulated more selectively at the glioma site as demonstrated by in vivo and ex vivo imaging. As expected, the glioma-bearing mice treated with CK-NP-PTX achieved the longest median survival time compared to those treated with CVNHPAFAC-NP-PTX and K237-NP-PTX. These findings indicated that the multi-targeting therapy mediated by CK peptide might provide a promising way for glioblastoma therapy.

Glioblastoma multiforme: Pathogenesis and treatment

Each year, about 5-6 cases out of 100,000 people are diagnosed with primary malignant brain tumors, of which about 80% are malignant gliomas (MGs). Glioblastoma multiforme (GBM) accounts for more than half of MG cases. They are associated with high morbidity and mortality. Despite current multimodality treatment efforts including maximal surgical resection if feasible, followed by a combination of radiotherapy and/or chemotherapy, the median survival is short: only about 15months. A deeper understanding of the pathogenesis of these tumors has presented opportunities for newer therapies to evolve and an expectation of better control of this disease. Lately, efforts have been made to investigate tumor resistance, which results from complex alternate signaling pathways, the existence of glioma stem-cells, the influence of the blood-brain barrier as well as the expression of 0(6)-methylguanine-DNA methyltransferase. In this paper, we review up-to-date information on MGs treatment including current approaches, novel drug-delivering strategies, molecular targeted agents and immunomodulative treatments, and discuss future treatment perspectives.

[The stem cell niche in glioblastoma: from fundamental aspects to targeted therapies]

The concept of cancer stem cell (CSC) was established from models of leukemogenesis explaining tumor repopulation by the clonogenic properties of this specific population of tumoral cells. Among solid tumors, glioblastoma are currently the most documented models. Cancer stem cells reside in specific locations within tumors called niches. Anatomically, two complementary niches have been described in glioblastoma. The first one is a perivascular niche composed of vessels (endothelial cells, pericytes) and their microenvironment (integrins, interleukins) constitutive the nest of "normal" neural stem cells and cancer stem cells. The second one is a hypoxic niche found in regions with low oxygen tension such as the core of the tumor. In these niches, mutual interactions between CSC and their microenvironment involving the activation of multiple signaling pathways promote stemness maintenance and tumor propagation. The median overall survival of glioblastoma does not exceed 15 months despite an aggressive multimodal treatment, thus the therapeutic targeting of these niches, by systemic agents or radiotherapy, in order to inhibit the signaling pathways involved in the maintenance of the CSC niches, represents a major challenge. The combination of these two strategies appears promising and many clinical trials are underway.

Hedgehog signaling in the pathogenesis of neuro-oncology diseases

The review summarizes current knowledge on the Hedgehog signaling pathway, its role in normal embryogenesis and/or initiation and progression of neuro-oncological diseases, especially of high-grade gliomas, the most malignant neuroepithelial tumors. The main proteins forming the Hedgehog signaling pathway include Shh, PTCH1, SMO, HHIP, SUFU and GLI1 isoforms. Effects of other signaling pathways on the family of transcription factors GLI and other proteins are described. The review summarizes modern data about the impact of the Hedgehog signaling pathway on proliferation, migration activity and invasiveness, and also on tumor neoangiogenesis and tumor cell chemoresistance. The role of the Hedgehog signaling pathway in origin of cancer stem cells and epithelial-mesenchymal transition is also analyzed. Some prospects for new anticancer drugs acting on components of the Hedgehog signaling pathway inhibitors are demonstrated.

MicroRNA-338-3p inhibits colorectal carcinoma cell invasion and migration by targeting smoothened

OBJECTIVE

To investigate the regulative effect of microRNA-338-3p on colorectal carcinoma cell invasion and migration.

METHODS

The microRNA-338-3p expression pattern of colorectal carcinoma tissues and cell lines was detected by real-time reverse transcriptase polymerase chain reaction. The protein level of smoothened was detected by western blot analysis. Furthermore, colorectal carcinoma cells were pretreated with or without anti-smoothened-small interfering ribonucleic acid prior to the addition of pre-microRNA-338-3p or anti-microRNA-338-3p. The status of colorectal carcinoma cell invasion and that of migration were detected by transwell assay and wound healing assay, respectively.

RESULTS

The expression of microRNA-338-3p was significantly down-regulated in colorectal carcinoma tissues in comparison with those in the adjacent non-tumorous tissues, and the value was negatively related to advanced tumor, node, metastasis stage and local invasion. The expression of microRNA-338-3p in colorectal carcinoma cells transfected with pre-microRNA-338-3p p was significantly increased. Furthermore, over-expression of microRNA-338-3p inhibited the expression of smoothened protein in colorectal carcinoma cells, which showed obviously suppressed invasion and migration ability. The expression of microRNA-338-3p in colorectal carcinoma cells transfected with anti-microRNA-338-3p was significantly decreased. Moreover, the down-regulated expression of microRNA-338-3p caused the up-regulated expression of smoothened protein in colorectal carcinoma cells, which showed significantly enhanced invasion and migration ability. However, anti-smoothened-small interfering ribonucleic acid largely, but not completely, reversed the effects induced by blockage of microRNA-338-3p, suggesting that the regulative effect of microRNA-338-3p on colorectal carcinoma cell invasion and migration was indeed mediated by smoothened. Additionally, smoothened was identified as a direct target of microRNA-338-3p by luciferase assay.

CONCLUSIONS

MicroRNA-338-3p could inhibit colorectal carcinoma cell invasion and migration by inhibiting smoothened expression.

Curcumin suppresses malignant glioma cells growth and induces apoptosis by inhibition of SHH/GLI1 signaling pathway in vitro and vivo

AIMS

To study the role of curcumin on glioma cells via the SHH/GLI1 pathway in vitro and vivo.

METHODS

The effects of curcumin on proliferation, migration, apoptosis, SHH/GLI1 signaling, and GLI1 target genes expression were evaluated in multiple glioma cell lines in vitro. A U87-implanted nude mice model was used to study the role of curcumin on tumor volume and the suppression efficacy of GLI1.

RESULTS

Curcumin showed cytotoxic effects on glioma cell lines in vitro. Both mRNA and protein levels of SHH/GLI1 signaling (Shh, Smo, GLI1) were downregulated in a dose- and time-dependent manner. Several GLI1-dependent target genes (CyclinD1, Bcl-2, Foxm1) were also downregulated. Curcumin treatment prevented GLI1 translocating into the cell nucleus and reduced the concentration of its reporter. Curcumin suppressed cell proliferation, colony formation, migration, and induced apoptosis which was mediated partly through the mitochondrial pathway after an increase in the ratio of Bax to Bcl2. Intraperitoneal injection of curcumin in vivo reduced tumor volume, GLI1 expression, the number of positively stained cells, and prolonged the survival period compared with the control group.

CONCLUSION

This study shows that curcumin holds a great promise for SHH/GLI1 targeted therapy against gliomas.

miRNA-338-3p suppresses cell growth of human colorectal carcinoma by targeting smoothened

AIM: To investigate the regulative effect of miRNA-338-3p (miR-338-3p) on cell growth in colorectal carcinoma (CRC).

METHODS: The lentiviral vector pLV-THM-miR-338-3p and pLV-THM-miR-338-3p-inhibitor were constructed. The recombinant viral vector encoding the pre-miR-338-3p or miR-338-3p-inhibitor and the two packaging plasmids psPAX2 and pMD2.G were cotransfected into human embryonic kidney 293T cells to package lentivirus. The supernatant containing the lentivirus particles was harvested to determine the viral titer, and this supernatant was then used to transduce CRC-derived cell line, SW-620. Flow cytometry was utilized for sorting the green fluorescent protein (GFP)⁺ cells to establish the SW-620 cell line stably expressing pre-miR-338-3p or miR-338-3p-inhibitor. Moreover, the expression of miR-338-3p was determined by real-time reverse transcriptase polymerase chain reaction, and Western blotting was used to detect the expression of the smoothened (SMO, the possible target of miR-338-3p) protein in SW-620 cells. Furthermore, the status of CRC cell proliferation and apoptosis were detected by 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay and flow cytometry, respectively.

RESULTS: Restriction enzyme digestion and DNA sequencing demonstrated that the lentiviral vector pLV-THM-miR-338-3p and pLV-THM-miR-338-3p-inhibitor were constructed successfully. GFP was expressed after the SW-620 cells were transduced by the lentivirus. Expression of miR-338-3p in SW-620 cells transduced with the lentivirus pLV-THM-miR-338-3p was significantly increased (relative expression 3.91 ± 0.51 vs 2.36 ± 0.44, P < 0.01). Furthermore, overexpression of miR-338-3p inhibited the expression of SMO protein in SW-620 cells, which showed obviously suppressed proliferation ability [cellular proliferation inhibition rate (CPIR) 61.9% ± 5.2% vs 41.6% ± 4.8%, P < 0.01]. Expression of miR-338-3p in SW-620 cells transduced with the lentivirus pLV-THM-miR-338-3p-inhibitor was significantly decreased (relative expression 0.92 ± 0.29 vs 2.36 ± 0.44, P < 0.01). Moreover, the downregulated expression of miR-338-3p caused upregulated expression of the SMO protein in SW-620 cells, which showed significantly enhanced proliferation ability (CPIR 19.2% ± 3.8% vs 41.6% ± 4.8%, P < 0.01). However, anti-SMO-siRNA largely, but not completely, reversed the effects induced by blockage of miR-338-3p, suggesting that the regulative effect of miR-338-3p on CRC cell growth was indeed mediated by SMO.

CONCLUSION: miR-338-3p could suppress CRC growth by inhibiting SMO protein expression.

Construction of lentivirus-based inhibitor of hsa-microRNA-338-3p with specific secondary structure

AIM

To construct a lentivirus-based inhibitor with specific secondary structure that could exert long-term suppression on microRNA-338-3p (miR-338-3p), thus elucidating its molecular function in colorectal carcinoma cells.

METHODS

The miR-338-3p inhibitor sequence was synthesized and inserted into pLV-THM plasmid. HEK-293T cells were co-transfected with the lentiviral vectors pLV-THM-miR-338-3p-inhibitor, psPAX2, and pMD2.G. The supernatant containing the lentivirus particles was harvested to determine the viral titer, and then used to infect colorectal carcinoma-derived SW-620 cells. eGFP(+) cells were sorted using flow cytometry. The expression of miR-338-3p in SW-620 cells was determined with real-time RT-PCR, and the expression of the smoothened (SMO) protein was detected using Western blot analysis. The migration ability of the transfected SW-620 cells was assessed with transwell assay.

RESULTS

Restriction endonuclease analysis and DNA sequencing demonstrated that the lentiviral vector pLV-THM-miR-338-3p-inhibitor was successfully constructed. The expression of miR-338-3p in SW-620 cells was significantly decreased by infection with the lentivirus pLV-THM-miR-338-3p-inhibitor. Moreover, the down-regulated expression of miR-338-3p caused up-regulated expression of the SMO protein in SW-620 cells, which showed significantly enhanced migration in transwell assay.

CONCLUSION

The construction of the lentiviral vector pLV-THM-miR-338-3p-inhibitor with specific secondary structure provides a basis for further studies the molecular function of miR-338-3p in colorectal carcinoma. miR-338-3p may suppress SMO gene expression and thereby inhibit colorectal carcinoma migration.

Hedgehog signaling in glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most malignant brain tumor in adults with a median survival of 14.6 mo under the best available treatment. New treatment strategies are therefore urgently required, for which a profound understanding of tumor biology is necessary. Much effort has been devoted to tumor-specific aberrant signaling processes. Recently it was discovered that the transcription factor Gli1, which is activated by hedgehog signaling, is a highly predictive marker in GBM, as determined by immunohistochemistry. To determine whether GBM cells have transcriptionally active Gli1, we performed experiments with reporter genes with cells isolated from surgically removed human tumors and cell lines. We also determined whether the hedgehog signaling inhibitor cyclopamine influences reporter gene expression and cell viability, and we determined the expression of Gli1, SHH and Patched1 by quantitative real-time RT-PCR. Reporter gene analysis of nine cultures and four cell lines demonstrated a significantly enhanced transcriptional activity in six tumor cell cultures and all cell lines. Analysis of cell viability in the presence of cyclopamine revealed a response of all cell cultures with the exception of one primary culture and one cell line, but only one cell line responded to cyclopamine with reduced hedgehog signaling activity. This indicates that the toxicity of cyclopamine toward GBM cells is independent from hedgehog signaling. Since no correlation between hedgehog activity and SHH, Gli1 and Patched1 mRNA levels was observed we conclude that other mechanisms aside from transcriptional regulation of these factors are responsible for hedgehog activity in tumor cells derived from GBM.

Hedgehog signaling pathway mediates invasion and metastasis of hepatocellular carcinoma via ERK pathway

AIM

To investigate the role of Hedgehog (Hh) signaling pathway in the invasion and metastasis of human hepatocellular carcinoma (HCC).

METHODS

Eighty six HCC tissues samples and HCC cell line Bel-7402 were examined. The protein expression of sonic hedgehog (Shh), nuclear glioma-associated oncogene-1 (Gli1), MMP-9 and p-ERK1/2 in HCC was analyzed using immunohistochemistry and Western blot analysis. Boyden chamber assay and wound-healing assay were used to quantify the invasion and metastasis of Bel-7402 cells.

RESULTS

In 86 HCC tissue samples, the positive ratio of Shh and nucleus Gli1 was 67.44% (58/86) and 60.47% (52/86), respectively; the expression of nucleus Gli1 was correlated with the tumor pathological grade (P=0.034), and with the ability of the tumor to invade and metastasize (P=0.001); the expression of nucleus Gli1 was also correlated with p-ERK1/2 (P=0.031) and with MMP-9 (P=0.034). Neither Shh, nor nucleus Gli1 was observed in normal liver tissue. KAAD-cyclopamine (KAAD-cyc), a specific inhibitor of the Hh pathway, at the concentrations of 1 and 4 μmol/L inhibited the invasion and migration of Bel-7402 cells and decreased the expression of Gli1 in nucleus and MMP-9, p-ERK1/2 proteins in Bel-7402 cells. On the other hand, Shh, a ligand of the Hh pathway, at the concentration of 0.5 μg/mL produced opposite effects. The MAPK pathway inhibitors U0126 and PD98059 at the concentrations of 5 and 10 μmol/L inhibited invasion and metastasis of Bel-7402 cells induced by Shh, and decreased the expression of p-ERK1/2 and MMP-9. However, U0126 and PD98059 had no effect on the expression of Gli1.

CONCLUSION

Hh signaling pathway mediates invasion and metastasis of human HCC by up-regulating the protein expression of MMP-9 via ERK pathway.

Hedgehog signaling: networking to nurture a promalignant tumor microenvironment

In addition to its role in embryonic development, the Hedgehog pathway has been shown to be an active participant in cancer development, progression, and metastasis. Although this pathway is activated by autocrine signaling by Hedgehog ligands, it can also initiate paracrine signaling with cells in the microenvironment. This creates a network of Hedgehog signaling that determines the malignant behavior of the tumor cells. As a result of paracrine signal transmission, the effects of Hedgehog signaling most profoundly influence the stromal cells that constitute the tumor microenvironment. The stromal cells in turn produce factors that nurture the tumor. Thus, such a resonating cross-talk can amplify Hedgehog signaling, resulting in molecular chatter that overall promotes tumor progression. Inhibitors of Hedgehog signaling have been the subject of intense research. Several of these inhibitors are currently being evaluated in clinical trials. Here, we review the role of the Hedgehog pathway in the signature characteristics of cancer cells that determine tumor development, progression, and metastasis. This review condenses the latest findings on the signaling pathways that are activated and/or regulated by molecules generated from Hedgehog signaling in cancer and cites promising clinical interventions. Finally, we discuss future directions for identifying the appropriate patients for therapy, developing reliable markers of efficacy of treatment, and combating resistance to Hedgehog pathway inhibitors.

Targeting GLI1 expression in human inflammatory breast cancer cells enhances apoptosis and attenuates migration

Background:

Inflammatory breast cancer (IBC) is an aggressive subtype of breast cancer with distinct molecular profiles. Gene expression profiling previously identified sonic hedgehog (SHH) as part of a gene signature that is differentially regulated in IBC patients.

Methods:

The effects of reducing GLI1 levels on protein expression, cell proliferation, apoptosis and migration were determined by immunoblots, MTT assay, Annexin-V/PI assay and conventional and automated cell migration assays.

Results:

Evaluation of a panel of breast cancer cell lines revealed elevated GLI1 expression, typically a marker for hedgehog-pathway activation, in a triple-negative, highly invasive IBC cell line, SUM149 and its isogenic-derived counterpart rSUM149 that has acquired resistance to ErbB1/2 targeting strategies. Downregulation of GLI1 expression in SUM149 and rSUM149 by small interfering RNA or a small molecule GLI1 inhibitor resulted in decreased proliferation and increased apoptosis. Further, GLI1 suppression in these cell lines significantly inhibited cell migration as assessed by a wound-healing assay compared with MCF-7, a non-invasive cell line with low GLI1 expression. A novel high-content migration assay allowed us to quantify multiple effects of GLI1 silencing including significant decreases in cell distance travelled and linearity of movement.

Conclusion:

Our data reveal a role for GLI1 in IBC cell proliferation, survival and migration, which supports the feasibility of targeting GLI1 as a novel therapeutic strategy for IBC patients.

Role of sonic hedgehog signaling in migration of cell lines established from CD133-positive malignant glioma cells

The sonic hedgehog (SHH) signaling pathway is essential for normal development and embryogenic morphogenesis. In malignant neoplasms its inappropriate activation correlates with tumorigenesis, proliferation, and migration. However, the role of SHH in infiltrative growth of glioblastoma remains to be elucidated. CD133 is a marker of tumor stem cells in glioblastoma, which are thought to play important roles in tumorigenesis, drug resistance, and tumor recurrence. We investigated the role of the SHH signaling pathway in migration of glioblastoma cell lines derived from CD133-positive cells. Two cell lines, GBM1 and GBM2, were established from CD133-positive cells sorted on an automagnetic cell separator from dispersed human glioblastoma cells. Both cell lines exhibited sphere-like growth in serum-free medium containing growth factor. Expression of patched (PTCH)-, a receptor of SHH, of smoothened (SMO)-, a 7 transmembrane receptor, and of GLI1- and GLI2, PTCH cascade signal proteins, was evaluated by reverse-transcription polymerase chain reaction (RT-PCR). The effects of recombinant SHH in the medium, and of knockdown of SMO-, GLI1- or GLI2 messenger RNA (mRNA) on the migratory ability of neoplastic cells were evaluated by scratch assays. RT-PCR revealed the presence of PTCH-, SMO-, GLI1-, and GLI2 mRNA in these cells. Their migratory ability was significantly enhanced (P < 0.05) by addition of recombinant SHH to the medium. Knockdown of SMO-, GLI1- or GLI2 mRNA resulted in significant decrease in the mobility of the neoplastic cells. Our study suggests that the SHH pathway plays an important role in the migratory ability of cells derived from CD133-positive human glioblastoma cells.

Molecular alterations in glioblastoma: potential targets for immunotherapy

Glioblastoma is the most common and deadly brain tumor, possibly arising from genetic and epigenetic alterations in normal astroglial cells. Multiple cytogenetic, chromosomal, and genetic alterations have been identified in glioblastoma, with distinct expression of antigens (Ags) and biomarkers that may alter therapeutic potential of this aggressive cancer. Current therapy consists of surgical resection, followed by radiation therapy and chemotherapy. In spite of these treatments, the prognosis for glioblastoma patients is poor. Although recent studies have focused on the development of novel immunotherapeutics against glioblastoma, little is known about glioblastoma-specific immune responses. A better understanding of the molecular interactions among glioblastoma tumors, host immune cells, and the tumor microenvironment may give rise to novel integrated approaches for the simultaneous control of tumor escape pathways and the activation of antitumor immune responses. This review provides a detailed overview concerning genetic alterations in glioblastoma, their effects on Ag and biomarker expression, and the future design of chemoimmunotherapeutics against glioblastoma.