Transcriptional silencing of hedgehog-interacting protein by CpG hypermethylation and chromatic structure in human gastrointestinal cancer

Breathing new life into the study of COPD with genes identified from genome-wide association studies

COPD is a major cause of morbidity and mortality globally. While the significance of environmental exposures in disease pathogenesis is well established, the functional contribution of genetic factors has only in recent years drawn attention. Notably, many genes associated with COPD risk are also linked with lung function. Because reduced lung function precedes COPD onset, this association is consistent with the possibility that derangements leading to COPD could arise during lung development. In this review, we summarise the role of leading genes (HHIP, FAM13A, DSP, AGER and TGFB2) identified by genome-wide association studies in lung development and COPD. Because many COPD genome-wide association study genes are enriched in lung epithelial cells, we focus on the role of these genes in the lung epithelium in development, homeostasis and injury.

Emerging trends in gastrointestinal cancers: Targeting developmental pathways in carcinogenesis and tumor progression

Gastrointestinal carcinomas are a group of cancers associated with the digestive system and its accessory organs. The most prevalent cancers related to the gastrointestinal tract are colorectal, gall bladder, gastric, hepatocellular, and esophageal cancers, respectively. Molecular aberrations in different signaling pathways, such as signal transduction systems or developmental pathways are the chief triggering mechanisms in different cancers Though a massive advancement in diagnostic and therapeutic interventions results in improved survival of patients with gastrointestinal cancer; the lower malignancy stages of these carcinomas are comparatively asymptomatic. Various gastrointestinal-related cancers are detected at advanced stages, leading to deplorable prognoses and increased rates of recurrence. Recent molecular studies have elucidated the imperative roles of several signaling pathways, namely Wnt, Hedgehog, and Notch signaling pathways, play in the progression, therapeutic responsiveness, and metastasis of gastrointestinal-related cancers. This book chapter gives an interesting update on recent findings on the involvement of developmental signaling pathways their mechanistic insight in gastrointestinalcancer. Subsequently, evidences supporting the exploration of gastrointestinal cancer related molecular mechanisms have also been discussed for developing novel therapeutic strategies against these debilitating carcinomas.

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.

B13, a well-tolerated inhibitor of hedgehog pathway, exhibited potent anti-tumor effects against colorectal carcinoma in vitro and in vivo

Abnormal activation of Hedgehog (Hh) signaling pathway mediates the genesis and progression of various tumors [1]. Currently, three drugs targeting the Hh signaling component Smoothened (Smo) have been marketed for the clinical treatment of basal cell tumors or acute myeloid leukemia. However, drug resistance is a common problem in those drugs, so the study of Smo inhibitors that can overcome drug resistance has important guiding significance for clinical adjuvant drugs. MTT assay, clone formation assay and EdU assay were used to detect the proliferation inhibitory activity of the drugs on tumor cells. The effect of B13 on cell cycle and apoptosis were detected by flow cytometry. An acute toxicity test was used to detect the toxicity of B13 in vivo, and xenograft tumor model was used to detect the efficacy of B13 in vivo. The binding of B13 to Smo was studied by BODIPY-cyclopamine competitive binding assay and molecular docking. The effect of B13 on the expression and localization of downstream target gene Gli1/2 of Smo was investigated by Western Blot and immunofluorescence assay. Smo^D473H mutant cell line was constructed to study the effect of B13 against drug resistance. (1) B13 had the strongest inhibitory activity against colorectal cancer cells. (2) B13 can effectively inhibit the clone formation and EdU positive rate of colon cancer cells. (3) B13 can block the cell cycle in the G2/M phase and cell apoptosis. (4) B13 has low toxicity in vivo, and its efficacy in vivo is better than that of the Vismodegib. (5) Molecular docking and BODIPY-cyclopamine experiments showed that B13 could bind to Smo protein. (6) B13 can inhibit the protein expression of Gli1, the downstream of Smo, and inhibit its entry into the nucleus. (7) B13 could inhibit the expression of Gli1 in the HEK293 cells with Smo^D473H, and the molecular docking results showed that B13 could bind Smo^D473H protein. B13 with the best anti-tumor activity was screened out by MTT assay. In vitro, pharmacodynamics experiments showed that B13 could effectively inhibit the proliferation and metastasis of colorectal cancer cells, induce cell cycle arrest, and induce cell apoptosis. In vivo pharmacodynamics experiments showed that B13 was superior to Vismodegib in antitumor activity and had low toxicity in vivo. Mechanism studies have shown that B13 can bind Smo protein, inhibit the expression of downstream Gli1 and its entry into the nucleus. Notably, B13 overcomes resistance caused by Smo^D473H mutations.

Targets for Renal Carcinoma Growth Control Identified by Screening FOXD1 Cell Proliferation Pathways

Simple Summary

FOXD1 regulates the proliferation of clear cell renal cell carcinoma (ccRCC) cells, and ccRCC cells in which FOXD1 has been inactivated do not form tumors efficiently in an animal model. Reproducing growth inhibition in tumor cells by inhibiting FOXD1 pathways presents a possible therapeutic approach for ccRCC and other cancers. We have established an analysis strategy to identify FOXD1-regulated target pathways that may be therapeutically tractable, and compounds that modulate these pathways were selected for testing. Targets in three pathways were identified: FOXM1, PME1, and TMEM167A, which were inhibited by compounds FDI-6, AMZ-30, and silibinin, respectively. The effects of these compounds on the growth of tumor cells from patients cultured in a novel 3D tumor-replica culture environment revealed that FDI-6 and silibinin had strong growth inhibitory effects. This investigation informs new therapeutic targets to control ccRCC tumor growth, and provides a strategy to compare the responsiveness of individual patient tumor replicas to growth-inhibitory compounds.

Abstract

Clinical association studies suggest that FOXD1 is a determinant of patient outcome in clear cell renal cell carcinoma (ccRCC), and laboratory investigations have defined a role for this transcription factor in controlling the growth of tumors through regulation of the G2/M cell cycle transition. We hypothesized that the identification of pathways downstream of FOXD1 may define candidates for pharmacological modulation to suppress the G2/M transition in ccRCC. We developed an analysis pipeline that utilizes RNA sequencing, transcription factor binding site analysis, and phenotype validation to identify candidate effectors downstream from FOXD1. Compounds that modulate candidate pathways were tested for their ability to cause growth delay at G2/M. Three targets were identified: FOXM1, PME1, and TMEM167A, which were targeted by compounds FDI-6, AMZ-30, and silibinin, respectively. A 3D ccRCC tumor replica model was used to investigate the effects of these compounds on the growth of primary cells from five patients. While silibinin reduced 3D growth in a subset of tumor replicas, FDI-6 reduced growth in all. This study identifies tractable pathways to target G2/M transition and inhibit ccRCC growth, demonstrates the applicability of these strategies across patient tumor replicas, and provides a platform for individualized patient testing of compounds that inhibit tumor growth.

Signaling Pathways Involved in 5-FU Drug Resistance in Cancer

Anti-metabolite drugs prevent the synthesis of essential cell growth compounds. 5-fluorouracil is used as an anti-metabolic drug in various cancers in the first stage of treatment. Unfortunately, in some cancers, 5-fluorouracil has low effectiveness because of its drug resistance. Studies have shown that drug resistance to 5-fluorouracil is due to the activation of specific signaling pathways and increased expressions of enzymes involved in drug metabolites. However, when 5-fluorouracil is used in combination with other drugs, the sensitivity of cancer cells to 5-fluorouracil increases, and the effect of drug resistance is reversed. This study discusses how the function of 5-fluorouracil in JAK/STAT, Wnt, Notch, NF-κB, and hedgehogs in some cancers.

Advances in understanding of relationship between Hhip and Lpar2 gene expression and gastric cancer

Gastric cancer (GC) is a malignant tumor derived from gastric mucosal epithelial cells. In recent years, it has been found that the Hhip and Lpar2 genes play an important role in the development of GC. The Hhip gene can inhibit the proliferation and invasion of GC cells by participating in the Hedgehog signaling pathway, while the Lpar2 gene promotes the development of GC by activating the ATX-LPA signaling pathway. In this paper, we will review the changes of expression levels, molecular mechanism, and clinical application of Hhip and Lpar2 genes in GC patients.

Downregulation of hedgehog-interacting protein (HHIP) contributes to hexavalent chromium-induced malignant transformation of human bronchial epithelial cells

Hexavalent chromium [Cr(VI)] is a potent human lung carcinogen. Multiple mechanisms have been proposed that contribute to Cr(VI)-induced lung carcinogenesis including oxidative stress, DNA damage, genomic instability and epigenetic modulation. However, the molecular mechanisms and pathways mediating Cr(VI) carcinogenicity have not been fully elucidated. Hedgehog (Hh) signaling is a key pathway that plays important roles in the formation of multiple tissues during embryogenesis and in the maintenance of stem cell populations in adults. Dysregulation of Hh signaling pathway has been reported in many human cancers. Here, we report a drastic reduction in both mRNA and protein levels of hedgehog-interacting protein (HHIP), a downstream target and a negative regulator of Hh signaling, in Cr(VI)-transformed cells. These findings point to a potential role of Hh signaling in Cr(VI)-induced malignant transformation and lung carcinogenesis. Cr(VI)-transformed cells exhibited DNA hypermethylation and silencing histone marks in the promoter region of HHIP, indicating that an epigenetic mechanism mediates Cr(VI)-induced silencing of HHIP. In addition, the major targets of Hh signaling (GLI1-3 and PTCH1) were significantly increased in Cr(VI)-transformed cells, suggesting an aberrant activation of Hh signaling in these cells. Moreover, ectopically expressing HHIP not only suppressed Hh signaling but also inhibited cell proliferation and anchorage-independent growth in Cr(VI)-transformed cells. In conclusion, these findings establish a novel regulatory mechanism underlying Cr(VI)-induced lung carcinogenesis and provide new insights for developing a better diagnostic and prognostic strategy for Cr(VI)-related human lung cancer.

GLI1: A Therapeutic Target for Cancer

GLI1 is a transcriptional effector at the terminal end of the Hedgehog signaling (Hh) pathway and is tightly regulated during embryonic development and tissue patterning/differentiation. GLI1 has low-level expression in differentiated tissues, however, in certain cancers, aberrant activation of GLI1 has been linked to the promotion of numerous hallmarks of cancer, such as proliferation, survival, angiogenesis, metastasis, metabolic rewiring, and chemotherapeutic resistance. All of these are driven, in part, by GLI1’s role in regulating cell cycle, DNA replication and DNA damage repair processes. The consequences of GLI1 oncogenic activity, specifically the activity surrounding DNA damage repair proteins, such as NBS1, and cell cycle proteins, such as CDK1, can be linked to tumorigenesis and chemoresistance. Therefore, understanding the underlying mechanisms driving GLI1 dysregulation can provide prognostic and diagnostic biomarkers to identify a patient population that would derive therapeutic benefit from either direct inhibition of GLI1 or targeted therapy towards proteins downstream of GLI1 regulation.

DNA methylation in Hepatoblastoma-a literature review

Hepatoblastoma (HB) is the most common malignant liver tumor in children. Abnormal activation of the Wnt/β-catenin signaling pathway plays an important role in the formation and development of HB. Genes in HB show a global hypomethylation change, accompanied by hypermethylation of specific tumor suppressor genes (TSGs). This article reviews the hypermethylation changes in several TSGs, such as RASSF1A, SOCS1, APC, HHIP, and P16, and analyzes the pathways and mechanisms of TSGs regulating gene expression. The role of the methylation-regulating enzymes DNA methyltransferases (DNMTs) and ten-eleven translocation (TET) family members enzymes in the methylation changes of HB was analyzed, and it was speculated that the occurrence of HB is partly due to the obstruction of liver differentiation in the early stage of differentiation. The origin cells may be incompletely differentiated hepatocytes remaining in the liver of children after birth. Therefore, further studying the role of methylation regulating enzymes in methylation changes in HB is a promising future research direction.

Comprehensive LC-MS/MS-based phytochemical perspectives and osteogenic effects of Uraria crinita

Osteogenesis plays a vital role in the maintenance of bone health. Imbalances in osteogenesis influence the onset of several bone loss-associated diseases. The intake of Uraria crinita (Fabaceae) through dietary supplements is advised for childhood bone dysplasia. This botanical provides edible tonics and detoxifiers, and is also used as a folk beverage. We evaluated the osteogenic effects of a 50% ethanol extract of the root of U. crinita on primary human osteoblasts (HObs) and initiated a novel comprehensive phytochemical strategy using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for quality control of this functional food. Two isoflavones, genistein (5) and 5,7-dihydroxy-3',5'-dihydroxyisoflavone (6), increased the alkaline phosphatase activity (differentiation stage); the flavone glycoside vitexin (1), and the phenolic acid salicylic acid (2) enhanced the mineralization (mature stage). The isoflavone 2'-hydroxygenistein (4) possessed high osteogenic potential among the isolated compounds in HObs. It promoted osteogenesis-related stages and upregulated the gene expressions in a dose-dependent manner. The major compounds in the active fraction were quantitatively analyzed via phytochemical fingerprint detection. These LC-MS/MS-based phytochemical perspectives can act as reference standards in developing food supplements from U. crinita.

In vitro and in vivo evaluation of the neuroprotective activity of Uncaria hirsuta Haviland

The incidence of neurodegeneration leading to the conditions such as Alzheimer's and Parkinson's diseases are on the increase, they require the approaches that focus on protection prevention rather than treatment. Plants are rich sources of many compounds which possess medicinal properties. We sought to investigate the neuroprotective effects of Uncariahirsuta and its compounds on d-galactose-induced stress in BALB/c mice as well as 6-hydroxydopamine (6-OHDA)-induced stress in mouse nerve growth factor (mNGF)-differentiated PC12 cells. Our results demonstrate that the 95% ethanol extract of U. hirsuta reversed the d-galactose-induced learning and memory dysfunctions and decreased the malodialdehyde levels. Furthermore, the isolated compounds, 5β-carboxystrictosidine (1) and chlorogenic acid (2), protected mNGF-differentiated PC12 cells against toxicity induced by 6-OHDA by acting as antiapoptotic agents. The 50% inhibitory concentration (IC₅₀) for intracellular reactive oxygen species (ROS) scavenging was found to be 24.5 (for 1) and 19.7 μM (for 2), and both 1 and 2 reduced intracellular calcium levels with respective IC₅₀ values of 46.9 and 27 μM. Interestingly, both compounds inhibited caspase 3 and 9 activities with respective IC₅₀ values of 25.6 and 24.5 μM for 1 and 19.4 and 16.3 μM for 2. Our results identify U. hirsuta and its active compounds as potential neuroprotective agents and deserve further evaluation for drug development for neuroprotection in the future.

Histone methyltransferase SUV39H2 regulates cell growth and chemosensitivity in glioma via regulation of hedgehog signaling

Background

Malignant glioma is one of the essentially incurable tumors with chemoresistance and tumor recurrence. As a histone methyltransferase, SUV39H2 can trimethylate H3K9. SUV39H2 is highly expressed in many types of human tumors, while the function of SUV39H2 in the development and progression of glioma has never been elucidated.

Methods

RT-qPCR and IHC were used to test SUV39H2 levels in glioma tissues and paired normal tissues. The clinical relevance of SUV39H2 in glioma was analyzed in a public database. Colony formation assays, CCK-8 assays, and flow cytometry were conducted to explore the role of SUV39H2 in the growth of glioma cells in vitro. A cell line-derived xenograft model was applied to explore SUV39H2’s role in U251 cell proliferation in vivo. Sphere formation assays, RT-qPCR, flow cytometry, and IF were conducted to illustrate the role of SUV39H2 in the stemness and chemosensitivity of glioma. Luciferase reporter assays and WB were applied to determine the function of SUV39H2 in Hh signaling.

Results

SUV39H2 was highly expressed in glioma tissues relative to normal tissues. SUV39H2 knockdown inhibited cell proliferation and stemness and promoted the chemosensitivity of glioma cells in vitro. In addition, SUV39H2 knockdown also significantly inhibited glioma cell growth in vivo. Moreover, we further uncovered that SUV39H2 regulated hedgehog signaling by repressing HHIP expression.

Conclusions

Our findings delineate the role of SUV39H2 in glioma cell growth and chemosensitivity as a pivotal regulator of the hedgehog signaling pathway and may support SUV39H2 as a potential target for diagnosis and therapy in glioma management.

A Pilot Study Using a Multistaged Integrated Analysis of Gene Expression and Methylation to Evaluate Mechanisms for Evening Fatigue in Women Who Received Chemotherapy for Breast Cancer

CONTEXT

Fatigue is the most common symptom associated with cancer and its treatment. Investigation of molecular mechanisms associated with fatigue may identify new therapeutic targets.

OBJECTIVE

The objective of this pilot study was to evaluate the relationships between gene expression and methylation status and evening fatigue severity in women with breast cancer who received chemotherapy.

METHODS

Latent class analysis (LCA) was used to identify evening fatigue phenotypes. In this analysis, the lowest (i.e., moderate, n = 7) and highest (i.e., very high, n = 29) fatigue-severity classes identified using LCA were analyzed via two stages. First, a total of 32,609 transcripts from whole blood were evaluated for differences in expression levels between the classes. Next, 637 methylation sites located within the putative transcription factor binding sites for those genes demonstrating differential expression were evaluated for differential methylation state between the classes.

RESULTS

A total of 89 transcripts in 75 unique genes were differentially expressed between the moderate (the lowest fatigue-severity class identified) and very high evening fatigue classes. In addition, 23 differentially methylated probes and three differentially methylated regions were found between the moderate and very high evening fatigue classes.

CONCLUSIONS

Using a multistaged integrated analysis of gene expression and methylation, differential methylation was identified in the regulatory regions of genes associated with previously hypothesized mechanisms for fatigue, including inflammation, immune function, neurotransmission, circadian rhythm, skeletal muscle energy, carbohydrate metabolism, and renal function as well as core biological processes including gene transcription and the cell-cycle regulation.

Hedgehog Interacting Protein 1 is a Prognostic Marker and Suppresses Cell Metastasis in Gastric Cancer

Background: The gene Hedgehog interacting protein (HHIP) is a pivotal morphogen for multiple developmental processes. However, the expression and clinical correlation of HHIP in gastric cancer (GC) has not been fully investigated. Here, we aimed to explore the expression of HHIP in gastric cancer (GC) and evaluate its clinicopathological and functional correlations.

Methods: The expression of HHIP mRNA was first determined in the Human Protein Atlas (HPA) and The Cancer Genome Atlas (TCGA) GC database and then validated by RT-qPCR (n = 41) and immunohistochemistry (IHC, n = 95) in a cohort of in-house GC patients and in 29 cases of gastric intraepithelial neoplasia (GIN). The clinicopathological and functional relationship of HHIP with GC were also analyzed.

Results: We found that HHIP mRNA were significantly downregulated in GC in the TCGA and HPA databases, as well as in our in-house cohort (P < 0.05). HHIP mRNA is mainly located in the cell nucleus, while HHIP protein is mainly located in the cell cytoplasm. Moreover, the HHIP protein level in the GIN tissues was significantly higher than that in the GC tissues (P < 0.001) and significantly lower than that in adjacent normal controls (P < 0.001). In addition, low HHIP expression was correlated with lymphatic metastasis (P = 0.041), pTNM stage (P = 0.007) and nervous system invasion (P = 0.001). Furthermore, we observed strong positive correlations between HHIP protein expression and overall survival (P < 0.001) and disease-free survival (P = 0.027) in GC patients. HHIP protein expression was an independent prognostic factor for overall survival (P < 0.001). Functional experimental results showed that overexpression of HHIP attenuated the migration and invasion ability of GC cells (P < 0.01).

Conclusion: HHIP may be a promising tumor metastatic-suppressor and prognostic biomarker for gastric cancer.

Gastric cancer and Hedgehog signaling pathway: emerging new paradigms

Ever since its initial discovery in Drosophila, hedgehog signaling has been linked to foregut development, The mammalian genome expresses three Hedgehog paralogues, sonic hedgehog (Shh), Indian Hedgehog, and desert hedgehog. In the mucosa of the embryonic and adult foregut, Shh expression is the highest. It has now become clear that hedgehog signaling is of pivotal importance in gastric homeostasis. Aberrant activation of hedgehog signaling is associated with a range of pathological consequences including various cancers. Also in gastric cancer, clinical and preclinical data support a role of Hedgehog signaling in neoplastic transformation, and gastrointestinal cancer development, also through cancer stroma interaction. Technological advance are facilitating monitoring Hedgehog signaling broadening options for the more efficient screening of individuals predisposed to eventually developing gastric cancer and targeting Hedgehog signaling may provide opportunities for prophylactic therapy once atrophic gastritis develops. Nevertheless, convincing evidence that Hedgehog antagonists are of clinically useful in the context of gastric cancer is still conspicuously lacking. Here we analyze review the role of Hedgehog in gastric physiology and the potential usefulness of targeting Hedgehog signaling in gastric cancer.

Hedgehog signaling pathway in colorectal cancer: function, mechanism, and therapy

Colorectal cancer (CRC) is one of the most common gastrointestinal cancers worldwide. It is a complicated and often fatal cancer, and is related to a high disease-related mortality. Around 90% of mortalities are caused by the metastasis of CRC. Current treatment statistics shows a less than 5% 5-year survival for patients with metastatic disease. The development and metastasis of CRC involve multiple factors and mechanisms. The Hedgehog (Hh) signaling plays an important role in embryogenesis and somatic development. Abnormal activation of the Hh pathway has been proven to be related to several types of human cancers. The role of Hh signaling in CRC, however, remains controversial. In this review, we will go through previous literature on the Hh signaling and its functions in the formation, proliferation, and metastasis of CRC. We will also discuss the potential of targeting Hh signaling pathway in the treatment, prognosis, and prevention of CRC.

Hhip regulates tumor-stroma-mediated upregulation of tumor angiogenesis

Tumor growth is governed by the coordinated action of various types of cells that are present in the tumor environment. Fibroblasts, which constitute a major fraction of the stroma, participate actively in various signaling events and regulate tumor development and metastasis. The Hedgehog (Hh) pathway plays an important role in promoting tumor malignancy via fibroblasts; however, the role of hedgehog interacting protein (hhip; inhibitor of Hh pathway) in tumor growth is poorly understood. Here we implanted B16F10 tumors in hhip+/- mice to study the tumor growth characteristics and the vascular phenotype. Furthermore, the mechanism involved in the observed phenomena was explored to reveal the role of hhip in tumor growth. The tumors that were implanted in hhip+/- mice exhibited accelerated growth and increased tumor angiogenesis. Although we observed a decrease in hypoxia, blood vessels still had abnormal phenotype. We found that increased Hh signaling in tumor fibroblasts induced a high expression of vascular endothelial growth factor (VEGF), which subsequently resulted in an increased proliferation of endothelial cells. Thus, the heterozygous knockdown of hhip in mice could affect Hh signaling in tumor fibroblasts, which could cause the increased production of the growth factor VEGF. This signaling, via a paracrine effect on endothelial cells, increased tumor vascular density.

Prognostic significance of the methylation of Wnt pathway antagonists-CXXC4, DACT2, and the inhibitors of sonic hedgehog signaling-ZIC1, ZIC4, and HHIP in head and neck squamous cell carcinomas

Objectives

Aberrations in Wnt and Shh signaling pathways are related to the pathogenesis of head and neck carcinomas, and their activation frequently results from epigenetic alterations. This study aimed to assess the frequency of methylation of negative regulators of Wnt signaling: CXXC4, DACT2, HDPR1, and FBXW11 and Shh signaling: HHIP, PTCH1, SUFU, ZIC1, and ZIC4 and correlate it with clinicopathological features in this group of patients.

Materials and methods

Methylation-specific PCR was used to detect gene promoter methylation, and real-time PCR was used to assess gene expression level.

Results

The analysis of the occurrence of gene promoter methylation in head and neck carcinoma cell lines indicated that CXXC4, DACT2, HHIP, ZIC1, and ZIC4 are methylated in these tumors. These genes were further analyzed in tumor sections from oral and laryngeal cancer patients. Gene methylation rate was higher in laryngeal tumors. The methylation index in tumor samples correlated with the overall survival in a subgroup of oral cancer patients who died of the disease. Moreover, ZIC4 methylation correlated with lymph node involvement in oral cancer patients.

Conclusions

Our findings corroborate that the activation of Wnt signaling in head and neck squamous cell carcinoma (HNSCC) is related to epigenetic silencing of its negative regulators. Moreover, the results indicate that the same mechanism of activation may operate in the case of Shh signaling.

Clinical relevance

The methylation of ZIC4 may be considered a new prognostic marker in oral cavity and oropharyngeal tumors. Further investigations should determine the diagnostic significance of methylation of ZIC4, HHIP, and DACT2 in head and neck carcinomas.

Hedgehog pathway maintains cell survival under stress conditions, and drives drug resistance in lung adenocarcinoma

Hedgehog (HH) pathway plays an important role in embryonic development, but is largely inactive in adult except for tissue repair. Aberrant activation of HH pathway has been found in a variety of cancer types. In non-small cell lung cancer, however, the role and importance of HH pathway remain controversial. In the current study, we found that HH pathway was maintained in low activity in lung adenocarcinoma (LAC) cells under normal culture condition, but was highly induced in response to stress conditions. Activation of HH pathway promoted cell survival, growth, and invasion partially through HGF and MET signaling. Hedgehog-Interacting Protein (HHIP), a cell-surface negative regulator of HH pathway, was epigenetically silenced in LAC. Overexpression of HHIP blocked the activation of HH and HGF/MET pathways, and made cells significantly more susceptible to stress conditions. In LAC cells with acquired resistance to Epidermal Growth Factor Receptor Tyrosin Kinase Inhibitor (EGFR-TKI), we found that a part of tumor cells were much more sensitive to HH or HGF/MET inhibitors, suggesting an oncogenic addiction shift from EGFR to HH and HGF/MET pathways. In conclusion, this study showed that HH pathway is a survival signaling that drives LAC cell growth under stress conditions, and HHIP is a key regulator to block the induction of HH pathway. Targeting the HH pathway through inhibitors or HHIP thus holds promise to address EGFR-TKI resistance in LAC in clinic.

The Prognostic Significance of the Hedgehog Signaling Pathway in Colorectal Cancer

Despite significant advances in the management of colorectal cancer (CRC) the identification of new prognostic biomarkers continues to be a challenge. Since its initial discovery, the role of the Hedgehog (Hh) signaling pathway in carcinogenesis has been extensively studied. We herein review and comment on the prognostic significance of the Hh signaling pathway in CRC. The differential expression of Hh pathway components between malignant and nonmalignant conditions as well as correlation of Hh activation markers with various clinicopathological parameters and the effect on disease-free survival, overall survival, and disease recurrence in patients with CRC is summarized and discussed. According to the studies reviewed herein the activation of the Hh pathway seems to be correlated with adverse clinicopathological features and worse survival. However, to date study results show significant variability with regard to the effect on outcomes. Such results need to be interpreted carefully and emphasize the need for further well designed studies to characterize the actual influence of the Hh pathway in CRC prognosis.

The hedgehog antagonist HHIP as a favorable prognosticator in glioblastoma

Inactivation of hedgehog-interacting protein (HHIP) and overexpression of Gli1 play vital roles in the development of diverse human cancers. The aim of this study is to examine the association of HHIP and Gli1 with the clinicopathologic features and prognosis of patients with glioblastoma (GBM). The expression of HHIP and Gli1 in 103 patients with GBM and 32 control patients was investigated by immunohistochemistry. Statistical analysis was utilized to evaluate the association of HHIP as well as Gli1 with clinicopathological characteristics and prognosis of patients. HHIP and Gli1 were dysregulated in GBM. Spearman's rank analysis showed that HHIP and Gli1 had an inverse correlation (r = -0.386, P = 0.000). Expression of HHIP was significantly correlated with age (P = 0.000), gender (P = 0.003), seizure (P = 0.013), resection degree (P = 0.033), adjuvant treatment (P = 0.030), and O(6)-methylguanine-DNA methyltransferase (MGMT) methylation (P = 0.021), while Gli1 expression was significantly correlated with age (P = 0.002), gender (P = 0.033), Karnofsky performance status (KPS) score (P = 0.028), resection degree (P = 0.000), adjuvant treatment (P = 0.014), and MGMT methylation (P = 0.030). Kaplan-Meier method showed that patients with low Gli1 expression had longer overall survival (OS) than those with high Gli1 expression (P = 0.000) and the OS of the patients with HHIP-positive GBM was significantly longer than that of the patients with HHIP-negative GBM (P = 0.000). Univariate and multivariate analyses confirmed that HHIP expression and Gli1 expression were independent prognostic factors. Our data suggested that expression of HHIP could be considered as significant prognostic marker for patients with GBM.

Neurocytoprotective Effects of Aliphatic Hydroxamates from Lovastatin, a Secondary Metabolite from Monascus-Fermented Red Mold Rice, in 6-Hydroxydopamine (6-OHDA)-Treated Nerve Growth Factor (NGF)-Differentiated PC12 Cells

Lovastatin, a secondary metabolite isolated from Monascus-fermented red rice mold, has neuroprotective activity and permeates the blood-brain barrier. The aim of this study was to enhance the activity of lovastatin for potential use as a treatment for neuronal degeneration in Parkinson's disease. Six lovastatin-derived compounds were semisynthesized and screened for neurocytoprotective activity against 6-hydroxydopamine (6-OHDA)-induced toxicity in human neuroblastoma PC12 cells. Four compounds, designated as 3a, 3d, 3e, and 3f, significantly enhanced cell viability. In particular, compound 3f showed excellent neurocytoprotective activity (97.0 ± 2.7%). Annexin V-FITC and propidium iodide double staining and 4',6-diamidino-2-phenylindole staining indicated that compound 3f reduced 6-OHDA-induced apoptosis in PC12 cells. Compound 3f also reduced caspase-3, -8, and -9 activities, and intracellular calcium concentrations elevated by 6-OHDA in a concentration-dependent manner, without inhibiting reactive oxygen species generation. JC-1 staining indicated that compound 3f also stabilized mitochondrial membrane potential. Thus, compound 3f may be used as a neurocytoprotective agent. Future studies should investigate its potential application as a treatment for Parkinson's disease.

Epigenetic regulation of human hedgehog interacting protein in glioma cell lines and primary tumor samples

Glioma constitutes one of the most common groups of brain tumors, and its prognosis is influenced by different genetic and epigenetic modulations. In this study, we demonstrated low or no expression of hedgehog interacting protein (HHIP) in most of the cell lines and primary glioma tumor samples. We further proceeded to promoter methylation study of this gene in the same cell lines and primary tumor samples and found 87 % (7/8) HHIP methylation in glioblastoma cell lines and 75 % (33/44) in primary tumor samples. These methylation pattern correlates with low or unexpressed HHIP in both cell lines and primary tumor samples. Our results suggest the possibility of epigenetic regulation of this gene in glioma, similarly to medulloblastoma, gastric, hepatic, and pancreatic cancers. Also, HHIP might be a diagnostic or prognostic marker in glioma and help to the detection of these tumors in early stages of disease.

Role of PTCH1 gene methylation in gastric carcinogenesis

The present study aimed to investigate the role of PTCH1 methylation in gastric carcinogenesis and the therapeutic effect of the methylation inhibitor, 5-aza-2′-deoxycytidine (5-aza-dC), in the treatment of gastric cancer. Total RNA was extracted from 20 gastric cancer tissues, their corresponding adjacent normal tissues and a gastric cancer AGS cell line. PTCH1 mRNA expression was detected by quantitative PCR, and the PTCH1 methylation of the promoter was examined by methylation-specific PCR. The AGS cells were treated with 5-Aza-dC; apoptosis and the cell cycle were examined by flow cytometry, and the PTCH1 methylation level was observed. PTCH1 expression was negatively correlated with promoter methylation in the gastric cancer tissues, their corresponding adjacent normal tissues and the gastric cancer AGS cell line (r=−0.591, P=0.006). 5-Aza-dC treatment caused apoptosis and the G₀/G₁ phase arrest of the AGS cells, and also induced the demethylation and increased expression of PTCH1. In conclusion, the study found that the hypermethylation of the PTCH1 gene promoter region is one of the main causes of low PTCH1 expression in AGS cells. Demethylation agent 5-Aza-dC can reverse the methylation status of PTCH1 and regulate the expression of PTCH1, indicating its potential role in gastric cancer treatment.

DNA methylation subgroups and the CpG island methylator phenotype in gastric cancer: a comprehensive profiling approach

BACKGROUND

Methylation-induced silencing of promoter CpG islands in tumor suppressor genes plays an important role in human carcinogenesis. In colorectal cancer, the CpG island methylator phenotype (CIMP) is defined as widespread and elevated levels of DNA methylation and CIMP+ tumors have distinctive clinicopathological and molecular features. In contrast, the existence of a comparable CIMP subtype in gastric cancer (GC) has not been clearly established. To further investigate this issue, in the present study we performed comprehensive DNA methylation profiling of a well-characterised series of primary GC.

METHODS

The methylation status of 1,421 autosomal CpG sites located within 768 cancer-related genes was investigated using the Illumina GoldenGate Methylation Panel I assay on DNA extracted from 60 gastric tumors and matched tumor-adjacent gastric tissue pairs. Methylation data was analysed using a recursively partitioned mixture model and investigated for associations with clinicopathological and molecular features including age, Helicobacter pylori status, tumor site, patient survival, microsatellite instability and BRAF and KRAS mutations.

RESULTS

A total of 147 genes were differentially methylated between tumor and matched tumor-adjacent gastric tissue, with HOXA5 and hedgehog signalling being the top-ranked gene and signalling pathway, respectively. Unsupervised clustering of methylation data revealed the existence of 6 subgroups under two main clusters, referred to as L (low methylation; 28% of cases) and H (high methylation; 72%). Female patients were over-represented in the H tumor group compared to L group (36% vs 6%; P = 0.024), however no other significant differences in clinicopathological or molecular features were apparent. CpG sites that were hypermethylated in group H were more frequently located in CpG islands and marked for polycomb occupancy.

CONCLUSIONS

High-throughput methylation analysis implicates genes involved in embryonic development and hedgehog signaling in gastric tumorigenesis. GC is comprised of two major methylation subtypes, with the highly methylated group showing some features consistent with a CpG island methylator phenotype.

Induction of calcium sensing receptor in human colon cancer cells by calcium, vitamin D and aquamin: Promotion of a more differentiated, less malignant and indolent phenotype

The calcium sensing receptor (CaSR) is a robust promoter of differentiation in colonic epithelial cells and functions as a tumor suppressor. Cancer cells that do not express CaSR (termed CaSR null) are highly malignant while acquisition of CaSR expression in these cells circumvents the malignant phenotype. We hypothesize that chemopreventive agents mediate their action through the induction of CaSR. Here, we compare the effectiveness of Ca(2+), vitamin D, and Aquamin (a marine algae product containing Ca(2+), magnesium and detectable levels of 72 additional minerals) on the induction of CaSR in the CBS and HCT116 human colon carcinoma cell lines and the corresponding CaSR null cells isolated from these lines. All three agonists induced CaSR mRNA and protein expression and inhibited cellular proliferation in the parental and CaSR null cells. Aquamin was found to be most potent in this regard. Induction of CaSR expression by these agonists resulted in demethylation of the CaSR gene promoter with a concurrent increase in CaSR promoter reporter activity. However, demethylation per se did not induce CaSR transcription. Induction of CaSR expression resulted in a down-regulated expression of tumor inducers and up-regulated expression of tumor suppressors. Again, Aquamin was found to be most potent in these biologic effects. This study provides a rationale for the use of a multi-mineral approach in the chemoprevention of colon cancer and suggests that induction of CaSR may be a measure of the effectiveness of chemopreventive agents.

High expression of trimethylated histone H3 at lysine 27 predicts better prognosis in non-small cell lung cancer

Epigenetic parameters such as DNA methylation and histone modifications play pivotal roles in carcinogenesis. Global histone modification patterns have been implicated as possible predictors of cancer recurrence and prognoses in a great variety of tumor entities. Our study was designed to evaluate the association among trimethylated histone H3 at lysine 27 (H3K27me3), clinicopathological variables and outcome in early-stage non-small cell lung cancer (NSCLC). The expression of H3K27me3 and its methyl-transferase, enhancer of zeste homolog 2 (EZH2) together with proliferating cell nuclear antigen (PCNA) were evaluated by immunohistochemistry in normal lung tissue (n=5) and resected NSCLC patients (n=42). In addition, the specificity of antibody for H3K27me3 was tested by western blot analysis. The optimal cut-off point of H3K27me3 expression for prognosis was determined by the X-tile program. The prognostic significance was determined by means of Kaplan-Meier survival estimates and log-rank tests. As a result, enhanced trimethylation of H3K27me3 was correlated with longer overall survival (OS) and better prognosis (P<0.05). Moreover, both univariate and multivariate analyses indicated that H3K27me3 level was a significant and independent predictor of better survival (hazard ratio, 0.187; 95% confidence interval, 0.066-0.531, P=0.002). Furthermore, H3K27me3 expression was positively correlated with DNA methylation level at CCGG sites while reversely related to EZH2 expression (P<0.05). In conclusion, H3K27me3 level defines unrecognized subgroups of NSCLC patients with distinct epigenetic phenotype and clinical outcome, and can probably be used as a novel predictor for better prognosis in NSCLC patients.

Induction of CaSR expression circumvents the molecular features of malignant CaSR null colon cancer cells

We recently reported on the isolation and characterization of calcium sensing receptor (CaSR) null human colon cancer cells (Singh et al., Int J Cancer 2013; 132: 1996-2005). CaSR null cells possess a myriad of molecular features that are linked to a highly malignant and drug resistant phenotype of colon cancer. The CaSR null phenotype can be maintained in defined human embryonic stem cell culture medium. We now show that the CaSR null cells can be induced to differentiate in conventional culture medium, regained the expression of CaSR with a concurrent reversal of the cellular and molecular features associated with the null phenotype. These features include cellular morphology, expression of colon cancer stem cell markers, expression of survivin and thymidylate synthase and sensitivity to fluorouracil. Other features include the expression of epithelial mesenchymal transition linked molecules and transcription factors, oncogenic miRNAs and tumor suppressive molecule and miRNA. With the exception of cancer stem cell markers, the reversal of molecular features, upon the induction of CaSR expression, is directly linked to the expression and function of CaSR because blocking CaSR induction by shRNA circumvented such reversal. We further report that methylation and demethylation of the CaSR gene promoter underlie CaSR expression. Due to the malignant nature of the CaSR null cells, inclusion of the CaSR null phenotype in disease management may improve on the mortality of this disease. Because CaSR is a robust promoter of differentiation and mediates its action through diverse mechanisms and pathways, inactivation of CaSR may serve as a new paradigm in colon carcinogenesis.

Chemical and biological evaluation of nephrocizin in protecting nerve growth factor-differentiated PC12 cells by 6-hydroxydopamine-induced neurotoxicity

The neurotoxin 6-hydroxydopamine (6-OHDA) has been widely used to generate an experimental model of Parkinson's disease. This model is crucial in the search for compounds that diminish 6-OHDA-induced nerve growth factor (NGF)-differentiated PC12 cell death. Nephrocizin (luteolin-7-O-β-D-glucopyranoside), a flavone glycoside, was isolated from widely distributed plants. The protective effects of pre-treatment with nephrocizin on the induced neurotoxicity in PC12 cells by 6-OHDA and its oxidative products, H₂O₂-, and p-quinone, were evaluated herein. Nephrocizin promoted cell viability, scavenged ROS-related products, increased cellular glutathione (GSH) levels, and reduced caspase-3 and -8 activities in 6-OHDA-, H₂O₂-, or p-quinone-treated PC12 cells. Furthermore, nephrocizin-conjugated metabolites in PC12 cells were identified with the boronate-affinity method and LC-MS technology, and preferential regioselectivity at the C2' and C5' positions by the nephrocizin-GSH (or NAC) adduct method was observed. These lines of evidence established that nephrocizin could form a dimer to diminish the intracellular ROS. These results demonstrate the first neuroprotective mechanism of nephrocizin against 6-OHDA-, H₂O₂- or p-quinone-induced cytotoxicity in PC12 cells via chemical and biological studies. These dietary antioxidants are potential candidates for use in intervention in neurodegenerative diseases.

Identification of signature genes for detecting hedgehog signaling activation in gastric cancer

The aim of this study was to investigate the expression of hedgehog signaling molecules in gastric cancer. In situ hybridization, immunohistochemistry and RT-PCR for hedgehog signaling molecules, smoothened (SMO), suppressor of fused [Su(Fu)], and the target genes hedgehog-interacting protein (HIP) and platelet-derived growth factor receptor α (PDGFRα) were performed in 30 gastric cancer and two gastritis specimens. Using in situ hybridization, SMO expression was detected in 18/30 cancerous specimens (60%) as well as in 1/2 gastritis specimens (50%). Su(Fu) was expressed in 15/30 (50%), HIP in 14/30 (≈47%), and PDGFRα in 6/30 (20%) gastric cancer specimens. Despite the heterogeneous expression pattern, SMO, Su(Fu) and PDGFRα transcripts were highly correlated with the HIP transcript in the 30 gastric cancer specimens (p=0.0006, 0.0003 and 0.0441, respectively). Results from the in situ hybridization were further confirmed by RT-PCR for the expression of all of the genes and by immunohistochemistry for SMO expression. The findings revealed a set of genes for detecting Hh signaling activation in gastric cancer.

Guidance for life, cell death, and colorectal neoplasia by netrin dependence receptors

This review is focusing on a critical mediator of embryonic and postnatal development with multiple implications in inflammation, neoplasia, and other pathological situations in brain and peripheral tissues. These morphogenetic guidance and dependence processes are involved in several malignancies targeting the epithelial and immune systems including the progression of human colorectal cancers. We consider the most important findings and their impact on basic, translational, and clinical cancer research. Expected information can bring new cues for innovative, efficient, and safe strategies of personalized medicine based on molecular markers, protagonists, signaling networks, and effectors inherent to the Netrin axis in pathophysiological states.

Stromal cells expressing hedgehog-interacting protein regulate the proliferation of myeloid neoplasms

Aberrant reactivation of hedgehog (Hh) signaling has been described in a wide variety of human cancers including cancer stem cells. However, involvement of the Hh-signaling system in the bone marrow (BM) microenvironment during the development of myeloid neoplasms is unknown. In this study, we assessed the expression of Hh-related genes in primary human CD34⁺ cells, CD34⁺ blastic cells and BM stromal cells. Both Indian Hh (Ihh) and its signal transducer, smoothened (SMO), were expressed in CD34⁺ acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS)-derived cells. However, Ihh expression was relatively low in BM stromal cells. Remarkably, expression of the intrinsic Hh-signaling inhibitor, human Hh-interacting protein (HHIP) in AML/MDS-derived stromal cells was markedly lower than in healthy donor-derived stromal cells. Moreover, HHIP expression levels in BM stromal cells highly correlated with their supporting activity for SMO⁺ leukemic cells. Knockdown of HHIP gene in stromal cells increased their supporting activity although control cells marginally supported SMO⁺ leukemic cell proliferation. The demethylating agent, 5-aza-2′-deoxycytidine rescued HHIP expression via demethylation of HHIP gene and reduced the leukemic cell-supporting activity of AML/MDS-derived stromal cells. This indicates that suppression of stromal HHIP could be associated with the proliferation of AML/MDS cells.

Hedgehog signaling: from the cuirass to the heart of pancreatic cancer

Exocrine pancreatic cancer is the fifth cause of cancer-related death in Europe and carries a very poor prognosis for all disease stages. To date no medical treatment has significantly increased patients' survival. One of the reasons for pancreatic cancer's chemoresistence is the complex tumor architecture: cancer cells are surrounded by a dense desmoplastic stroma that blocks drug delivery. Moreover, pancreatic cancer is characterized by a marked heterogeneity of cells, including cancer stem cells (CSCs) that act as tumor-initiating cells and hierarchically control the differentiated cancer cells. In particular, this subpopulation is resistant to classic cytotoxic therapies, and seems to be responsible for disease renewal. Hedgehog signaling (HH) is implicated in pancreatic gland development during embryogenesis and is reactivated during tumorigenesis and the maintenance of pancreatic cancer. Some studies demonstrated that the Hedgehog-secreted signaling proteins are overexpressed in both the stromal and CSCs pools, implying an abnormal activation of HH in the main compartment of pancreatic cancer. For this reason, the Hedgehog pathway could be an interesting target for clinical trials to increase drug concentration in neoplastic cells and hence deplete the stroma and directly kill tumor-initiating cells.

Identification of a chronic obstructive pulmonary disease genetic determinant that regulates HHIP

Multiple intergenic single-nucleotide polymorphisms (SNPs) near hedgehog interacting protein (HHIP) on chromosome 4q31 have been strongly associated with pulmonary function levels and moderate-to-severe chronic obstructive pulmonary disease (COPD). However, whether the effects of variants in this region are related to HHIP or another gene has not been proven. We confirmed genetic association of SNPs in the 4q31 COPD genome-wide association study (GWAS) region in a Polish cohort containing severe COPD cases and healthy smoking controls (P = 0.001 to 0.002). We found that HHIP expression at both mRNA and protein levels is reduced in COPD lung tissues. We identified a genomic region located ∼85 kb upstream of HHIP which contains a subset of associated SNPs, interacts with the HHIP promoter through a chromatin loop and functions as an HHIP enhancer. The COPD risk haplotype of two SNPs within this enhancer region (rs6537296A and rs1542725C) was associated with statistically significant reductions in HHIP promoter activity. Moreover, rs1542725 demonstrates differential binding to the transcription factor Sp3; the COPD-associated allele exhibits increased Sp3 binding, which is consistent with Sp3's usual function as a transcriptional repressor. Thus, increased Sp3 binding at a functional SNP within the chromosome 4q31 COPD GWAS locus leads to reduced HHIP expression and increased susceptibility to COPD through distal transcriptional regulation. Together, our findings reveal one mechanism through which SNPs upstream of the HHIP gene modulate the expression of HHIP and functionally implicate reduced HHIP gene expression in the pathogenesis of COPD.

Epigenetic inactivation of calcium-sensing receptor in colorectal carcinogenesis

Ca2+ is a chemopreventive agent for colon cancer. Ion transport systems are often altered in human cancer. The aim of this study was to clarify the alterations of calcium-sensing receptor (CASR), a member of the G protein-coupled receptor family, in colorectal carcinogenesis. We analyzed the expression of CASR in colorectal cancer cell lines and in cancer and adenoma tissues by RT-PCR and immunostaining. In addition, we analyzed methylation of the CASR promoter by using bisulfite sequence analysis and methylation-specific PCR. CASR mRNA and protein expression was significantly downregulated in most of the cancer cell lines. CpG islands were densely methylated in cancer cell lines with reduced CASR mRNA expression. Treatment with a demethylating agent, 5-aza-2'-deoxycytidine, and/or a histone deacetylase inhibitor, trichostatin A, restored CASR expression in the cancer cell lines. Disruption of CASR expression in CASR-unmethylated HCT-8 cells blocked the enhancing effect of Ca2+ on the cytotoxic response to 5-fluorouracil. CASR expression was observed in normal colonic epithelial cells and was retained in most adenoma tissues. CASR mRNA and protein expression was significantly downregulated in cancer tissues. There was an inverse relationship between CASR expression and degree of differentiation. Immunohistochemical CASR staining was reduced more predominantly in less-differentiated cancer tissues and/or in cancer cells at the invasive front, where nuclear/cytoplasmic β-catenin was often localized. CASR methylation was detected in 69% of colorectal cancer tissues and 90% of lymph node metastatic tissues and was significantly correlated with reduced CASR expression. CASR methylation was also detected in 32% of advanced adenoma tissues but was detected in only 9% of adenoma tissues and was not detected in hyperplastic polyp tissues. CASR methylation seems to occur at an early stage and progress in colorectal carcinogenesis. The results suggest that epigenetic inactivation of CASR has an important role in colorectal carcinogenesis.

Identification of signature genes for detecting hedgehog pathway activation in esophageal cancer

The hedgehog signaling pathway plays an important role in cell growth and differentiation both in normal embryonic development and in tumors. Our previous work shows that hedgehog pathway is frequently activated in esophageal cancers. To further elucidate the role of hedgehog pathway in esophageal cancers we examined the expression of the target genes, hedgehog-interacting protein (HIP) and platelet derived growth factor receptor alpha (PDGFRα) and hedgehog signaling molecules, smoothened (SMO), suppressor of fused (Su(Fu)) in the specimens using in-situ hybridization and RT-PCR. We found that HIP, PDGFRα, SMO and Su(Fu) gene highly expressed in the primary esophageal squamous cell carcinomas but not in normal esophageal tissue. The transcripts of HIP, PDGFRα and SMO were expressed in 13 of 15 esophageal cancers. Su(Fu) expression was missing in 2 esophageal cancers. The results from in-situ hybridization were further confirmed by RT-PCR. Our results revealed a set of genes for detecting hedgehog signaling activation in esophageal cancer.

Neurocytoprotective effects of the bioactive constituents of Pueraria thomsonii in 6-hydroxydopamine (6-OHDA)-treated nerve growth factor (NGF)-differentiated PC12 cells

Chronic neurodegenerative disorders are having an increasing impact on public health as human longevity increases. Parkinson's disease (PD) is a degenerative disorder of the central nervous system and is characterized by motor system disorders resulting in loss of dopamine-producing brain cells. Pueraria thomsonii Benth. (Fabaceae) is an herbal medicine that has traditionally been used as an antipyretic agent. In the present study, the active constituents, daidzein and genistein, were isolated from P. thomsonii. Both compounds exhibited neurocytoprotective effects against 6-hydroxydopamine (6-OHDA)-induced cytotoxicity in nerve growth factor (NGF)-differentiated PC12 cells. Neither daidzein nor genistein affected 6-OHDA-induced cellular reactive oxygen species (ROS) generation according to flow cytometric analysis. Rather, they inhibited caspase-8 and partially inhibited caspase-3 activation, providing a protective mechanism against 6-OHDA-induced cytotoxicity in NGF-differentiated PC12 cells. The present results imply that daidzein and genistein may be useful in the development of future strategies for the treatment of PD.

Frequent deregulations in the hedgehog signaling network and cross-talks with the epidermal growth factor receptor pathway involved in cancer progression and targeted therapies

The hedgehog (Hh)/glioma-associated oncogene (GLI) signaling network is among the most important and fascinating signal transduction systems that provide critical functions in the regulation of many developmental and physiological processes. The coordinated spatiotemporal interplay of the Hh ligands and other growth factors is necessary for the stringent control of the behavior of diverse types of tissue-resident stem/progenitor cells and their progenies. The activation of the Hh cascade might promote the tissue regeneration and repair after severe injury in numerous organs, insulin production in pancreatic beta-cells, and neovascularization. Consequently, the stimulation of the Hh pathway constitutes a potential therapeutic strategy to treat diverse human disorders, including severe tissue injuries; diabetes mellitus; and brain, skin, and cardiovascular disorders. In counterbalance, a deregulation of the Hh signaling network might lead to major tissular disorders and the development of a wide variety of aggressive and metastatic cancers. The target gene products induced through the persistent Hh activation can contribute to the self-renewal, survival, migration, and metastasis of cancer stem/progenitor cells and their progenies. Moreover, the pivotal role mediated through the Hh/GLI cascade during cancer progression also implicates the cooperation with other oncogenic products, such as mutated K-RAS and complex cross-talk with different growth factor pathways, including tyrosine kinase receptors, such as epidermal growth factor receptor (EGFR), Wnt/beta-catenin, and transforming growth factor-beta (TGF-beta)/TGF-beta receptors. Therefore, the molecular targeting of distinct deregulated gene products, including Hh and EGFR signaling components and other signaling elements that are frequently deregulated in highly tumorigenic cancer-initiating cells and their progenies, might constitute a potential therapeutic strategy to eradicate the total cancer cell mass. Of clinical interest is that these multitargeted approaches offer great promise as adjuvant treatments for improving the current antihormonal therapies, radiotherapies, and/or chemotherapies against locally advanced and metastatic cancers, thereby preventing disease relapse and the death of patients with cancer.

Extent and patterns of MGMT promoter methylation in glioblastoma- and respective glioblastoma-derived spheres

PURPOSE

Quantitative methylation-specific tests suggest that not all cells in a glioblastoma with detectable promoter methylation of the O6-methylguanine DNA methyltransferase (MGMT) gene carry a methylated MGMT allele. This observation may indicate cell subpopulations with distinct MGMT status, raising the question of the clinically relevant cutoff of MGMT methylation therapy. Epigenetic silencing of the MGMT gene by promoter methylation blunts repair of O6-methyl guanine and has been shown to be a predictive factor for benefit from alkylating agent therapy in glioblastoma.

EXPERIMENTAL DESIGN

Ten paired samples of glioblastoma and respective glioblastoma-derived spheres (GS), cultured under stem cell conditions, were analyzed for the degree and pattern of MGMT promoter methylation by methylation-specific clone sequencing, MGMT gene dosage, chromatin status, and respective effects on MGMT expression and MGMT activity.

RESULTS

In glioblastoma, MGMT-methylated alleles ranged from 10% to 90%. In contrast, methylated alleles were highly enriched (100% of clones) in respective GS, even when 2 MGMT alleles were present, with 1 exception (<50%). The CpG methylation patterns were characteristic for each glioblastoma exhibiting 25% to 90% methylated CpGs of 28 sites interrogated. Furthermore, MGMT promoter methylation was associated with a nonpermissive chromatin status in accordance with very low MGMT transcript levels and undetectable MGMT activity.

CONCLUSIONS

In MGMT-methylated glioblastoma, MGMT promoter methylation is highly enriched in GS that supposedly comprise glioma-initiating cells. Thus, even a low percentage of MGMT methylation measured in a glioblastoma sample may be relevant and predict benefit from an alkylating agent therapy.

Human hedgehog interacting protein expression and promoter methylation in medulloblastoma cell lines and primary tumor samples

Medulloblastoma is the most common pediatric brain tumor and its development is affected by genetic and epigenetic factors. In this study we found there is low or no expression of the hedgehog interacting protein (HHIP), a negative regulator of the sonic hedgehog pathway, in most medulloblastoma cell lines and primary samples explored. We proceeded to promoter methylation assays of this gene by MCA-Meth, and found that HHIP was hypermethylated in all medulloblastoma cell lines, but only in 2 out of 14 (14%) primary tumor samples. Methylation correlated with low or unexpressed HHIP in cell lines but not in primary tumor samples. These results suggest the possibility of epigenetic regulation of HHIP in medulloblastoma, similarly to gastric, hepatic and pancreatic cancer. However, HHIP seems to be not only under regulation of promoter methylation, but under other factors involved in the control of its low levels of expression in medulloblastoma.

Association of glypican-3 expression with growth signaling molecules in hepatocellular carcinoma

AIM: To clarify the association of glypican-3 (GPC3) expression with Wnt and other growth signaling molecules in hepatocellular carcinoma (HCC).

METHODS: Expression of GPC3, Wnt, matrix metalloproteinases (MMPs), sulfatase (SULF)1, SULF2, and other growth signaling molecules was analyzed in HCC cell lines and tissue samples by real-time reverse transcription-polymerase chain reaction, immunoblotting, and/or immunostaining. Expression of various genes in GPC3 siRNA-transfected HCC cells was analyzed.

RESULTS: GPC3 was overexpressed in most HCCs at mRNA and protein levels and its serum levels were significantly higher in patients with HCC than in non-HCC subjects (P < 0.05). Altered expressions of various MMPs and growth signaling molecules, some of which were correlated with GPC3 expression, were observed in HCCs. Down-regulation of GPC3 expression by siRNA in GPC3-overexpressing HCC cell lines resulted in a significant decrease in expressions of MMP2, MMP14, fibroblast growth factor receptor 1, insulin-like growth factor 1 receptor. GPC3 expression was significantly correlated with nuclear/cytoplasmic localization of β-catenin.

CONCLUSION: These results suggest that GPC3, in conjunction with MMPs and growth signaling molecules, might play an important role in the progression of HCC.

Hedgehog signaling and gastrointestinal cancer

Hedgehog (Hh) signaling is critical for embryonic development and in differentiation, proliferation, and maintenance of multiple adult tissues. De-regulation of the Hh pathway is associated with birth defects and cancer. In the gastrointestinal tract, Hh ligands Sonic (Shh) and Indian (Ihh), as well as the receptor Patched (Ptch1), and transcription factors of Glioblastoma family (Gli) are all expressed during development. In the adult, Shh expression is restricted to the stomach and colon, while Ihh expression occurs throughout the luminal gastrointestinal tract, its expression being highest in the proximal duodenum. Several studies have demonstrated a requirement for Hh signaling during gastrointestinal tract development. However to date, the specific role of the Hh pathway in the adult stomach and intestine is not completely understood. The current review will place into context the implications of recent published data related to the biochemistry and cell biology of Hh signaling on the luminal gastrointestinal tract during development, normal physiology and subsequently carcinogenesis.

Gene expression profiling supports the hypothesis that human ovarian surface epithelia are multipotent and capable of serving as ovarian cancer initiating cells

BACKGROUND

Accumulating evidence suggests that somatic stem cells undergo mutagenic transformation into cancer initiating cells. The serous subtype of ovarian adenocarcinoma in humans has been hypothesized to arise from at least two possible classes of progenitor cells: the ovarian surface epithelia (OSE) and/or an as yet undefined class of progenitor cells residing in the distal end of the fallopian tube.

METHODS

Comparative gene expression profiling analyses were carried out on OSE removed from the surface of normal human ovaries and ovarian cancer epithelial cells (CEPI) isolated by laser capture micro-dissection (LCM) from human serous papillary ovarian adenocarcinomas. The results of the gene expression analyses were randomly confirmed in paraffin embedded tissues from ovarian adenocarcinoma of serous subtype and non-neoplastic ovarian tissues using immunohistochemistry. Differentially expressed genes were analyzed using gene ontology, molecular pathway, and gene set enrichment analysis algorithms.

RESULTS

Consistent with multipotent capacity, genes in pathways previously associated with adult stem cell maintenance are highly expressed in ovarian surface epithelia and are not expressed or expressed at very low levels in serous ovarian adenocarcinoma. Among the over 2000 genes that are significantly differentially expressed, a number of pathways and novel pathway interactions are identified that may contribute to ovarian adenocarcinoma development.

CONCLUSIONS

Our results are consistent with the hypothesis that human ovarian surface epithelia are multipotent and capable of serving as the origin of ovarian adenocarcinoma. While our findings do not rule out the possibility that ovarian cancers may also arise from other sources, they are inconsistent with claims that ovarian surface epithelia cannot serve as the origin of ovarian cancer initiating cells.

Activation of hedgehog signaling is not a frequent event in ovarian cancers

The hedgehog (Hh) signaling pathway regulates many processes of development and tissue homeostasis. Activation of hedgehog signaling has been reported in about 30% of human cancer including ovarian cancer. Inhibition of hedgehog signaling has been pursued as an effective strategy for cancer treatment including an ongoing phase II clinical trial in ovarian cancer. However, the rate of hedgehog signaling activation in ovarian cancer was reported differently by different groups. To predict the successful for future clinical trials of hedgehog signaling inhibitors in ovarian cancer, we assessed hedgehog pathway activation in 34 ovarian epithelial tumor specimens through analyses of target gene expression by in-situ hybridization, immunohistochemistry, RT-PCR and real-time PCR. In contrast to previous reports, we only detected a small proportion of ovarian cancers with hedgehog target gene expression, suggesting that identification of the tumors with activated hedgehog signaling activation will facilitate chemotherapy with hedgehog signaling inhibitors.