Regulation of Hedgehog Signaling in Cancer by Natural and Dietary Compounds

Sucrose Stearates Stabilized Oil-in-Water Emulsions: Gastrointestinal Fate, Cell Cytotoxicity and Proinflammatory Effects after Simulated Gastrointestinal Digestion

Different structural composition ratios of sucrose stearates with hydrophilic-hydrophobic balance (HLB) values ranging from 1 to 16 on lipolysis in emulsion were investigated using a simulated gastrointestinal tract (GIT). Results showed a direct correlation between the HLB values of sucrose stearates and the lipolysis rate of emulsions, and a lower HLB value led to diminished lipolysis in the GIT simulation model. Mechanism study indicated that poor emulsifying capacity of sucrose stearates and lipolysis of sucrose stearates with lower HLB value inhibited the digestive behavior of oil. In addition, monoester was mainly hydrolyzed in the gastric phase, whereas sucrose polyesters caused lipolysis in the intestinal phase using an in vitro digestive model and HPLC analysis, further suppressing lipid digestion. Furthermore, a decrease in cell cytotoxicity and proinflammatory effects on Caco-2 and Raw264.7 were observed post-digestion, respectively. This work offers important insights into the effects of the degree of esterification of sucrose stearate on lipid digestion behavior in oil-in-water emulsions.

Exploring the Potential of Anthraquinone-Based Hybrids for Identifying a Novel Generation of Antagonists for the Smoothened Receptor in HH-Dependent Tumour

Natural products (NPs) are highly profitable pharmacological tools due to their chemical diversity and ability to modulate biological systems. Accessing new chemical entities while retaining the biological relevance of natural chemotypes is a fundamental goal in the design of novel bioactive compounds. Notably, NPs have played a crucial role in understanding Hedgehog (HH) signalling and its pharmacological modulation in anticancer therapy. However, HH antagonists developed so far have shown several limitations, thus growing interest in the design of second-generation HH inhibitors. Through smart manipulation of the NPs core-scaffold, unprecedented and intriguing architectures have been achieved following different design strategies. This study reports the rational design and synthesis of a first and second generation of anthraquinone-based hybrids by combining the rhein scaffold with variously substituted piperazine nuclei that are structurally similar to the active portion of known SMO antagonists, the main transducer of the HH pathway. A thorough functional and biological investigation identified RH2_2 and RH2_6 rhein-based hybrids as valuable candidates for HH inhibition through SMO antagonism, with the consequent suppression of HH-dependent tumour growth. These findings also corroborated the successful application of the NPs-based hybrid design strategy in the development of novel NP-based SMO antagonists.

Hedgehog signaling in tissue homeostasis, cancers, and targeted therapies

The past decade has seen significant advances in our understanding of Hedgehog (HH) signaling pathway in various biological events. HH signaling pathway exerts its biological effects through a complex signaling cascade involved with primary cilium. HH signaling pathway has important functions in embryonic development and tissue homeostasis. It plays a central role in the regulation of the proliferation and differentiation of adult stem cells. Importantly, it has become increasingly clear that HH signaling pathway is associated with increased cancer prevalence, malignant progression, poor prognosis and even increased mortality. Understanding the integrative nature of HH signaling pathway has opened up the potential for new therapeutic targets for cancer. A variety of drugs have been developed, including small molecule inhibitors, natural compounds, and long non-coding RNA (LncRNA), some of which are approved for clinical use. This review outlines recent discoveries of HH signaling in tissue homeostasis and cancer and discusses how these advances are paving the way for the development of new biologically based therapies for cancer. Furthermore, we address status quo and limitations of targeted therapies of HH signaling pathway. Insights from this review will help readers understand the function of HH signaling in homeostasis and cancer, as well as opportunities and challenges of therapeutic targets for cancer.

Garcinone C Suppresses Tumorsphere Formation and Invasiveness by Hedgehog/Gli1 Signaling in Colorectal Cancer Stem-like Cells

Hyperactivation of hedgehog signaling occurs in colorectal cancer stem-like cells (CSCs), a rare subpopulation, potentially involved in metastasis, chemotherapy resistance, and cancer relapse. Garcinone C, a xanthone isolated from mangosteen (Garcinia mangostana), suppresses colorectal cancer in vivo and in vitro by inhibiting Gli1-dependent noncanonical hedgehog signaling. Herein, we investigated the effect of garcinone C on cancer stemness and invasiveness in colorectal cancer; Gli1 was noted as pivotal in maintaining stemness and invasiveness in HCT116 and HT29 CSCs. Garcinone C inhibited the proliferation and self-renewal of HCT116 and HT29 CSCs. Colon cancer stemness markers such as CD44, CD133, ALDH1, and Nanog were significantly decreased by garcinone C. Computational studies showed that garcinone C showed a high affinity with the Gli1 protein ZF domain by forming hydrogen bonds with amino acid residues of ASP244, ARG223, and ASP216. Besides, MG132 blocked the effects of garcinone C on Gli1. Thus, garcinone C suppressed colorectal CSCs by binding to Gli1 and enhancing its degradation. MMP2 and MMP9 levels, invasive-related markers, were increased in HCT116 CSCs but decreased by garcinone C. E-cadherin level was reduced in HCT116 CSCs, while the presence of garcinone C was restored. Garcinone C inhibited the proliferation and invasiveness of colorectal CSCs by targeting Gli1-dependent Hh signaling. Garcinone C may be a potent natural agent against colorectal cancer relapse.

Cepharanthine hydrochloride inhibits the Wnt/β‑catenin/Hedgehog signaling axis in liver cancer

Cepharanthine, a biscoclaurine alkaloid isolated from the roots of Stephania cephalantha Hayata, has been reported to demonstrate antitumor activity across multiple cancer types; however, the mechanisms are still under investigation. High transcriptional responses by both the Hedgehog and Wnt pathways are frequently associated with specific human cancers, including liver cancer. To investigate whether these signaling pathways are involved in the pharmaceutical action of cepharanthine, we investigated Hedgehog and Wnt signaling in models of liver cancer treated with a semi‑synthetic cepharanthine derivative, cepharanthine hydrochloride (CH), in vitro and in vivo. By using MTT cytotoxic, scratch, Transwell, colony formation and flow cytometry assays, the pharmaceutical effect of CH was assessed. The compound was found to inhibit cellular proliferation and invasion, and promote apoptosis. Subsequent mechanistic investigations revealed that CH suppressed the Hedgehog/Gli1 signaling pathway by inhibiting Gli1 transcription and its transcriptional activity. CH also inhibited Wnt/β‑catenin signaling, and the pathway was found to be an upstream regulator of Hedgehog signaling in CH‑treated liver cancer cells. Finally, the antitumor effects of CH were demonstrated in an in vivo xenograft tumor model. Immunohistochemical analysis indicated that Gli1 protein levels were diminished in CH‑treated xenografts, compared with that noted in the controls. In summary, our results highlight a novel pharmaceutical antitumor mechanism of cepharanthine and provide support for CH as a clinical therapy for refractory liver cancer and other Wnt/Hedgehog‑driven cancers.

Natural Products Targeting Cancer Stem Cells for Augmenting Cancer Therapeutics

Cancer stem cells (CSC) have been identified in several types of solid tumors. In some cases, CSC may be the source of all the tumor cells, the cause of the tumor's resistance to chemotherapeutic agents, and the source of metastatic cells. Thus, a combination therapy targeting non-CSC tumor cells as well as specifically targeting CSCs holds the potential to be highly effective. Natural products (NPs) have been a historically rich source of biologically active compounds and are known for their ability to influence multiple signaling pathways simultaneously with negligible side effects. In this review, we discuss the potential of NPs in targeting multiple signaling pathways in CSC and their potential to augment the efficacy of standard cancer therapy. Specifically, we focus on the anti-CSC activities of flavonoids, FDA-approved drugs originating from natural sources. Additionally, we emphasize the potential of NPs in targeting microRNA-mediated signaling, given the roles of microRNA in the maintenance of the CSC phenotype.

Amentoflavone inhibits tumor necrosis factor-α-induced migration and invasion through AKT/mTOR/S6k1/hedgehog signaling in human breast cancer

Inflammatory cytokine tumor necrosis factor-α (TNFα) has been demonstrated to accelerate the progression and metastasis of various carcinomas. In this study, we investigated the effect of amentoflavone on inhibiting the migration and invasion of TNFα-induced breast cancer cells. Results showed that amentoflavone significantly blocked the cellular migration and invasion of MCF10DCIS.com and MDA-MB-231 cells at a concentration of 10 μM but did not affect the cell viability. The mRNA and protein levels of matrix metalloproteinase (MMP)-9, significantly activated by TNFα, were reversed by amentoflavone treatment in a dose-dependent manner in MCF10DCIS.com cells. Congruent with the protein level, the activity of MMP-9 was significantly suppressed by amentoflavone treatment. Additionally, we found that amentoflavone dampened Gli1-dependent noncanonical hedgehog signaling, which is a key factor in the regulation of migration and invasion in TNFα-induced human breast cancer cells. Further study elucidated that TNFα enhanced Gli1 through the activation of the AKT/mTOR/S6K1 cascade, whereas it receded after amentoflavone treatment in human breast cancer cells. In summary, amentoflavone abrogated Gli1 activation in TNFα-induced mammary tumor cells, resulting in a decrease of invasiveness in human breast cancer cells via mediating AKT/mTOR/S6K1 signaling. Amentoflavone should be considered as a potent food ingredient for the retardation of mammary tumorigenesis.

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.

Identification of Natural Compounds to Inhibit Sonic Hedgehog Pathway in Oral Cancer

BACKGROUND

Conventional treatment resistance remains a significant problem in cancer care. Cancer stem cells might play a major role in treatment resistance, and as a result, basic stem cell pathways are instrumental in cancer. Sonic Hedgehog signaling has not been widely studied in oral cancer, and being one of the major cancer stem cell pathways, targeting it with natural compounds could open many opportunities in the treatment scenario.

OBJECTIVE

The objective of the study was to identify the role of various natural compounds as an anti-cancer agent for oral cancer by targeting the Hedgehog signaling pathway.

METHODS

The selection of natural compounds were identified through literature review and NPACT database. The protein (3M1N and 3MXW) and ligand molecules were retrieved through the PDB and PubChem database. To carry out docking experiments, the AutoDock 4.2 program was used to study the interaction between the identified protein and ligand.

RESULTS

Among the 13 identified natural compounds, the top three were selected based on their binding energy. The higher the binding energy on the negative side, the better the interaction formed between protein and ligand. The natural compound showing best results with 3M1N protein were Butein, Biochanin-A, and Curcumin, whereas, with 3MXW, Zerumbone, Curcumin, and Butein were identified.

CONCLUSION

The identified natural compounds have shown better binding energy to bind the Hh ligands in the absence/presence of a known Sonic Hedgehog inhibitor. Based on the results, natural compounds can be utilized in the current treatment modality for oral cancer either as an individual anti-cancer agent or in combination with the known Sonic Hedgehog inhibitor to curb the increasing incidence rate. Yet, in-vitro evidence in lab setup is required.

Natural Products as a Promising Therapeutic Strategy to Target Cancer Stem Cells

Cancer is still a deadly disease, and its treatment desperately needs to be managed in a very sophisticated way through fast-developing novel strategies. Most of the cancer cases eventually develop into recurrencies, for which cancer stem cells (CSCs) are thought to be responsible. They are considered as a subpopulation of all cancer cells of tumor tissue with aberrant regulation of self-renewal, unbalanced proliferation, and cell death properties. Moreover, CSCs show a serious degree of resistance to chemotherapy or radiotherapy and immune surveillance as well. Therefore, new classes of drugs are rushing into the market each year, which makes the cost of therapy increase dramatically. Natural products are also becoming a new research area as a diverse chemical library to suppress CSCs. Some of the products even show promise in this regard. So, the near future could witness the introduction of natural products as a source of new chemotherapy modalities, which may result in the development of novel anticancer drugs. They could also be a reasonably-priced alternative to highly expensive current treatments. Nowadays, considering the effects of natural compounds on targeting surface markers, signaling pathways, apoptosis, and escape from immunosurveillance have been a highly intriguing area in preclinical and clinical research. In this review, we present scientific advances regarding their potential use in the inhibition of CSCs and the mechanisms by which they kill the CSCs.

Examining the developmental toxicity of piperonyl butoxide as a Sonic hedgehog pathway inhibitor

Piperonyl butoxide (PBO) is a semisynthetic chemical present in hundreds of pesticide formulations used in agricultural, commercial, and residential settings. PBO acts as a pesticide synergist by inhibiting insect cytochrome P450 enzymes and is often present at much higher concentrations than active insecticidal ingredients. PBO was recently discovered to also inhibit Sonic hedgehog (Shh) signaling, a key molecular pathway in embryonic development and in brain and face morphogenesis. Recent animal model studies have shown that in utero PBO exposure can cause overt craniofacial malformations or more subtle neurodevelopmental abnormalities. Related adverse developmental outcomes in humans are etiologically heterogeneous, and, while studies are limited, PBO exposure during pregnancy has been linked to neurodevelopmental deficits. Contextualized in PBO's newly recognized mechanism as a Shh signaling inhibitor, these findings support more rigorous examination of the developmental toxicity of PBO and its potential contribution to etiologically complex human birth defects. In this review, we highlight environmental sources of human PBO exposure and summarize existing animal studies examining the developmental impact of prenatal PBO exposure. Also presented are critical knowledge gaps in our understanding of PBO's pharmacokinetics and potential role in gene-environment and environment-environment interactions that should be addressed to better understand the human health impact of environmental PBO exposure.

Attenuation of hedgehog/GLI signaling by NT1721 extends survival in pancreatic cancer

BACKGROUND

Pancreatic cancer is one of the most lethal malignancies due to frequent late diagnosis, aggressive tumor growth and metastasis formation. Continuously raising incidence rates of pancreatic cancer and a lack of significant improvement in survival rates over the past 30 years highlight the need for new therapeutic agents. Thus, new therapeutic agents and strategies are urgently needed to improve the outcome for patients with pancreatic cancer. Here, we evaluated the anti-tumor activity of a new natural product-based epidithiodiketopiperazine, NT1721, against pancreatic cancer.

METHODS

We characterized the anticancer efficacy of NT1721 in multiple pancreatic cancer cell lines in vitro and in two orthotopic models. We also compared the effects of NT1721 to clinically used hedgehog inhibitors and the standard-of-care drug, gemcitabine. The effect of NT1721 on hedgehog/GLI signaling was assessed by determining the expression of GLI and GLI target genes both in vitro and in vivo.

RESULTS

NT1721 displayed IC₅₀ values in the submicromolar range in multiple pancreatic cancer cell lines, while largely sparing normal pancreatic epithelial cells. NT1721 attenuated hedgehog/GLI signaling through downregulation of GLI1/2 transcription factors and their downstream target genes, which reduced cell proliferation and invasion in vitro and significantly decreased tumor growth and liver metastasis in two preclinical orthotopic mouse models of pancreatic cancer. Importantly, treatment with NT1721 significantly improved survival times of mice with pancreatic cancer compared to the standard-of-care drug, gemcitabine.

CONCLUSIONS

Favorable therapeutics properties, i.e. 10-fold lower IC₅₀ values than clinically used hedgehog inhibitors (vismodegib, erismodegib), a 90% reduction in liver metastasis and significantly better survival times compared to the standard-of-care drug, gemcitabine, provide a rational for testing NT1721 in the clinic either as a single agent or possibly in combination with gemcitabine or other therapeutic agents in PDAC patients overexpressing GLI1/2. This could potentially result in promising new treatment options for patients suffering from this devastating disease.

POM121 is identified as a novel prognostic marker of oral squamous cell carcinoma

Background: The aim of this study was to confirm the role of nuclear pore membrane protein 121(POM121) in oral squamous cell carcinoma and to explore the underlying mechanism. Methods: POM121mRNA and protein expressions were evaluated in OSCC tissues and normal oral tissues by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry. The relationship between POM121 expression and clinical characteristics was analyzed. Bioinformatics analysis was performed to explore the possible mechanisms how POM121 affected OSCC. Results: We confirmed that POM121 mRNA expression in OSCC tissues was significantly higher than that in non-tumorous tissues, as was POM121 protein expression. POM121 expression was associated with distant metastasis and TNM stage. Multivariate analysis confirmed POM121 expression as an independent prognostic factor for OSCC patients. OSCC patients with high POM121 expression had a worse overall survival (OS) compared with patients with low POM121 expression. Bioinformatics analysis indicated POM121 may regulate OSCC through hedgehog and /or p53 signaling pathway. Conclusion: Targeting of POM121 expression levels could provide new diagnostic and therapeutic strategies for OSCC patients.

Hedgehog signalling in the tumourigenesis and metastasis of osteosarcoma, and its potential value in the clinical therapy of osteosarcoma

The Hedgehog (Hh) signalling pathway is involved in cell differentiation, growth and tissue polarity. This pathway is also involved in the progression and invasion of various human cancers. Osteosarcoma, a subtype of bone cancer, is commonly seen in children and adolescents. Typically, pulmonary osteosarcoma metastases are especially difficult to control. In the present paper, we summarise recent studies on the regulation of osteosarcoma progression and metastasis by downregulating Hh signalling. We also summarise the crosstalk between the Hh pathway and other cancer-related pathways in the tumourigenesis of various cancers. We further summarise and highlight the therapeutic value of potential inhibitors of Hh signalling in the clinical therapy of human cancers.