Notch signalling and voltage-gated Na+ channel activity in human prostate cancer cells: independent modulation of in vitro motility

Effect of Voltage-Gated Sodium Channel Inhibitors on the Metastatic Behavior of Prostate Cancer Cells: A Meta-Analysis

<b>Background and Objective:</b> Functional Voltage-Gated Sodium Channels (VGSCs) are expressed in metastatic prostate cancer (PCa) cells. A number of <i>in vitro</i> studies have evaluated the effect of functional VGSC expression on the metastatic cell behavior of PCa cells. This study aimed to evaluate the effect of VGSC inhibition on metastatic cell behavior in PCa cells by meta-analysis. <b>Materials and Methods:</b> Meta-analysis was performed on data taken from 13 publications that examined the effect of VGSC inhibitors on the metastatic cell behavior of metastatic PCa cells expressing functional VGSCs. The measure of effect was calculated according to the random effects model using mean differences and presented with a forest plot graph. Heterogeneity was checked using the Cochran's Q Test (Chi-square statistic) and the I² test statistic. In order to evaluate the objectivity, the funnels-plot graph was used. <b>Results:</b> The g value showing the effect size was calculated as 4.49 (95% CI = 5.35-3.62) in the experiments where Tetrodotoxin (TTX) was used, which has a very high specificity for VGSCs but is not licensed for clinical use. In experiments using licensed inhibitors Lamotrigine, Oxcarbazepine, Phenytoin, Ranolazine, Riluzole and Lidocaine, the g value was 1.37 (95 % CI = 2.02-0.71). Suppression of metastatic cell behavior in both subgroups is statistically significant (p<0.00001). <b>Conclusion:</b> Meta-analysis confirmed that VGSCs are an enhancing factor in the metastasis of PCa cells. The VGSCs appear to be an important target in the diagnosis and development of new treatment options in PCa.

Interplay of Developmental Hippo-Notch Signaling Pathways with the DNA Damage Response in Prostate Cancer

Prostate cancer belongs in the class of hormone-dependent cancers, representing a major cause of cancer incidence in men worldwide. Since upon disease onset almost all prostate cancers are androgen-dependent and require active androgen receptor (AR) signaling for their survival, the primary treatment approach has for decades relied on inhibition of the AR pathway via androgen deprivation therapy (ADT). However, following this line of treatment, cancer cell pools often become resistant to therapy, contributing to disease progression towards the significantly more aggressive castration-resistant prostate cancer (CRPC) form, characterized by poor prognosis. It is, therefore, of critical importance to elucidate the molecular mechanisms and signaling pathways underlying the progression of early-stage prostate cancer towards CRPC. In this review, we aim to shed light on the role of major signaling pathways including the DNA damage response (DDR) and the developmental Hippo and Notch pathways in prostate tumorigenesis. We recapitulate key evidence demonstrating the crosstalk of those pathways as well as with pivotal prostate cancer-related 'hubs' such as AR signaling, and evaluate the clinical impact of those interactions. Moreover, we attempt to identify molecules of the complex DDR-Hippo-Notch interplay comprising potentially novel therapeutic targets in the battle against prostate tumorigenesis.

miR-130b suppresses the invasion and migration of prostate cancer via inhibiting DLL1 and regulating the PI3K/Akt pathways

Prostate cancer occurs in the prostatic epithelium and poses a threat to the health of middle-aged and older males. The objective of the present study was to explore the roles of microRNA (miRNA/miR)-130b in prostate cancer and potential molecular mechanisms in order to control the migration and invasion of prostate cancer. For this purpose, reverse transcription-PCR was performed to evaluate the mRNA levels of DLL1, phosphoinositide-3 kinase (PI3K), protein kinase B (Akt) and matrix metalloproteinase (MMP)9, and western blot analysis was carried out to detect the protein expression levels of DLL1, phosphorylated (p)-PI3K, p-Akt and MMP9. A Transwell assay was conducted to examine the invasion rate of prostate cancer cells. Furthermore, a scratch wound assay was performed to examine the migration rate of prostate cancer cells. A luciferase assay was performed to examine the interaction between miRNA and its target mRNA. The results revealed that miR-130b had abnormal (low) expression in tumor tissues compared with that in the adjacent normal tissue. An miR-130b mimic suppressed the expression of DLL1. The expression of p-PI3K, p-Akt and MMP9 in prostate cancer cells transfected with the miR-130b mimic was decreased in comparison to the negative control and control groups. Furthermore, migration and invasion were significantly suppressed in the miR-130b mimic group. In conclusion, a novel pathway interlinking miR-130b and MMP9, p-Akt and p-PI3K, which regulates the migration and invasion of prostate cancer cells, was identified. These findings provide an intriguing biomarker and treatment strategy for patients with prostate cancer.

Antiandrogen abiraterone and docetaxel treatments affect Notch1, Jagged1 and Hes1 expressions in metastatic prostate cancer cells

BACKGROUND

Prostate cancer is the most common cancer in men. A Notch signaling pathway is an important pathway in cell proliferation, differentiation, and fate. However, currently, the effects of abiraterone based-anti-androgene therapy and docetaxel, the most commonly used standard chemotherapy in prostate cancer treatment, on Notch signaling pathway are unknown. This study aimed to investigate the effects of abiraterone acetate and docetaxel on the expression of Notch1, Jagged1 and Hes1 in prostate cancer cell lines.

METHODS

In vitro effects of abiraterone acetate and docetaxel were examined on Notch1, Jagged1, and Hes1 expression in LNCaP and PC3 PCa cell lines by immunofluorescence, Western blot, and qRT-PCR. MTT proliferation assay was used to evaluate cell proliferation and survival.

RESULTS

We found that in the treatment of PC3 cells with abiraterone acetate, docetaxel, and their combination, only mRNA expressions of Notch1, Jagged1 and Hes1 were affected compared to control, but these expression differences were not observed in protein expression. In LNCaP cells, abiraterone acetate and the combination groups reduced Notch1 protein expression. All treatment groups did not alter Jagged1 expression compared to control, but significantly increased the Hes1 gene and protein expression.

CONCLUSION

Our findings suggest that abiraterone and docetaxel treatments affects the expression of Notch signal pathway proteins. But these drugs especially cause significant upregulation in Hes1 expression in PCa cells. Therefore, co-application of Notch signaling inhibitors together with docetaxel and abiraterone chemotherapy, it was thought that decreased Hes1 expression could be stopped the deterioration of the prognosis of the patient.

Evaluation of the anticancer and anti-metastasis effects of novel synthetic sodium channel blockers in prostate cancer cells in vitro and in vivo

BACKGROUND

Voltage-gated sodium channels (VGSCs) are involved in several cellular processes related to cancer cell growth and metastasis, including adhesion, proliferation, apoptosis, migration, and invasion. We here in investigated the effects of S0154 and S0161, two novel synthetic sodium channel blockers (SCBs), on human prostate cancer cells (PC3, DU145, and LnCaP) and a prostate cancer xenograft model.

METHODS

The MTT assay was used to assess the anticancer effects of SCBs in PC3, DU145, and LnCaP cells. Sodium indicator and glucose uptake assays were used to determine the effects of S0154 and S0161 in PC3 cells. The impact of these SCBs on the proliferation, cell cycle, apoptosis, migration, and invasion of PC3 cells were determined using a CFDA-SE cell proliferation assay, cell cycle assay, annexin V-FITC apoptosis assay, transwell cell invasion assay, and wound-healing assay, respectively. The protein expression levels of Nav1.6, Nav1.7, CDK1, cyclin B1, MMP2, MMP9 in PC3 cells were analysis by Western blotting. The in vivo anticancer activity was evaluated using a PC3 xenograft model in nude mice.

RESULTS

S0154 and S0161 both showed anticancer and anti-metastatic effects against prostate cancer cells and significantly inhibited cell viability, with IC₅₀ values in the range of 10.51-26.60 μmol/L (S0154) and 5.07-11.92 μmol/L (S0161). Both compounds also increased the intracellular level of sodium, inhibited the protein expression of two α subunits of VGSCs (Nav1.6 and Nav1.7), and caused G2/M phase cell cycle arrest, with no or minor effects on cell apoptosis. Concentrations of 5 and 10 μmol/L of S0154 and S0161 significantly decreased the glucose uptake of PC3 cells. The compounds also inhibited the proliferation of PC3 cells and decreased their invasion in transwell assays. Furthermore, S0161 exerted antitumor activity in an in vivo PC3 xenograft model in nude mice, inhibiting the growth of the tumors by about 51% compared to the control group.

CONCLUSIONS

These results suggest that S0154 and S0161 have anticancer and anti-metastasis effects in prostate cancer cells both in vitro and in vivo, supporting their further development as potential therapeutic agents for prostate cancer.

The Notch-3 receptor: A molecular switch to tumorigenesis?

The Notch pathway is a highly conserved pathway increasingly implicated with the progression of human cancers. Of the four existing receptors associated with the pathway, the deregulation in the expression of the Notch-3 receptor is associated with more aggressive disease and poor prognosis. Selective targeting of this receptor has the potential to enhance current anti-cancer treatments. Molecular profiling strategies are increasingly incorporated into clinical decision making. This review aims to evaluate the clinical potential of Notch-3 within this new era of personalised medicine.

The Notch-1 receptor in prostate tumorigenesis

The Notch signalling pathway plays a fundamental role in tissue development due to its involvement in cell fate determination and postnatal tissue differentiation. Its capacity to regulate cell growth and development has been linked to the occurrence of several cancers including that of the prostate. The transmembrane receptor Notch-1 of this pathway has been linked to the oncogenic role of Notch signalling in prostate adenocarcinoma. Other studies have suggested a tumour suppressive function for Notch-1. This review focuses on the role of Notch-1 in prostate cancer development and maintenance and relates this to the fundamental role of Notch in normal prostate development. The current understanding of the aberrant Notch signalling characteristic of prostate cancer is discussed, and recent therapeutic advances in this field are presented.

Volatile Organic Compound Gamma-Butyrolactone Released upon Herpes Simplex Virus Type -1 Acute Infection Modulated Membrane Potential and Repressed Viral Infection in Human Neuron-Like Cells

Herpes Simplex Virus Type -1 (HSV-1) infections can cause serious complications such as keratitis and encephalitis. The goal of this study was to identify any changes in the concentrations of volatile organic compounds (VOCs) produced during HSV-1 infection of epithelial cells that could potentially be used as an indicator of a response to stress. An additional objective was to study if any VOCs released from acute epithelial infection may influence subsequent neuronal infection to facilitate latency. To investigate these hypotheses, Vero cells were infected with HSV-1 and the emission of VOCs was analyzed using two-dimensional gas chromatograph/mass spectrometry (2D GC/MS). It was observed that the concentrations of gamma-butyrolactone (GBL) in particular changed significantly after a 24-hour infection. Since HSV-1 may establish latency in neurons after the acute infection, GBL was tested to determine if it exerts neuronal regulation of infection. The results indicated that GBL altered the resting membrane potential of differentiated LNCaP cells and promoted a non-permissive state of HSV-1 infection by repressing viral replication. These observations may provide useful clues towards understanding the complex signaling pathways that occur during the HSV-1 primary infection and establishment of viral latency.

Hypoxia regulates Notch-3 mRNA and receptor activation in prostate cancer cells

The Notch-3 receptor is a recognized key regulator of vascular responses and is increasingly associated with tumorigenesis. Hypoxia-inducible factors activate specific signaling pathways such as Notch in a number of cellular models. This study aimed to evaluate the regulation of Notch-3 by hypoxia in prostate cancer cells. Notch-3 gene and protein expression was established in a panel of aerobic and hypoxic prostate cell lines in vitro, the CWR22 xenograft model and RNA extracted from low grade (Gleason score < = 6); high grade (Gleason score > = 7); non-hypoxic (low HIF, low VEGF); hypoxic (high HIF, high VEGF) patient FFPE specimens. NOTCH-3 was upregulated in PC3 (3-fold), 22Rv1 (4.1-fold) and DU145 (3.8-fold) but downregulated in LnCaP (12-fold) compared to the normal cell lines. NOTCH-3 expression was modified following hypoxic exposure in these cells. NOTCH-3 was upregulated (2.2-fold) in higher grade and hypoxic tumors, when compared to benign and aerobic pools. In the CWR22 xenograft model, Notch-3 expression was restored in castrate resistant tumors. Nuclear translocation of the Notch-3 intracellular domain was no longer detected following exposure of cells to hypoxia but not associated with a change in expression of HES-1. Our data further identifies Notch-3 as a potentially key hypoxic-responsive member of the Notch pathway in prostate tumorigenesis.

Notch signaling in the prostate: critical roles during development and in the hallmarks of prostate cancer biology

PURPOSE

This review aims to summarize the evidence that Notch signaling is associated with prostate development, tumorigenesis and prostate tumor progression.

METHODS

Studies in PubMed database were searched using the keywords of Notch signaling, prostate development and prostate cancer. Relevant literatures were identified and summarized.

RESULTS

The Notch pathway plays an important role in determining cell fate, proliferation, differentiation and apoptosis. Recent findings have highlighted the involvement of Notch signaling in prostate development and in the maintenance of adult prostate homeostasis. Aberrant Notch expression in tissues leads to dysregulation of Notch functions and promotes various neoplasms, including prostate cancer. High expression of Notch has been implicated in prostate cancer, and its expression increases with higher cancer grade. However, the precise role of Notch in prostate cancer has yet to be clearly defined. The roles of Notch either as an oncogene or tumor suppressor in prostate cancer hallmarks such as cell proliferation, apoptosis and anoikis, hypoxia, migration and invasion, angiogenesis as well as the correlation with metastasis are therefore discussed.

CONCLUSIONS

Notch signaling is a complicated signaling pathway in modulating prostate development and prostate cancer. Understanding and manipulating Notch signaling could therefore be of potential therapeutic value in combating prostate cancer.

Notch signaling in prostate cancer: refining a therapeutic opportunity

Notch is an evolutionarily conserved signaling pathway that plays a critical role in specifying cell fate and regulating tissue homeostasis and carcinogenesis. Studies using organ cultures and genetically engineered mouse models have demonstrated that Notch signaling regulates prostate development and homeostasis. However, the role of the Notch signaling pathway in prostate cancer remains inconclusive. Many published studies have documented consistent deregulation of major Notch signaling components in human prostate cancer cell lines, mouse models for prostate cancers, and human prostate cancer specimens at both the mRNA and the protein levels. However, functional studies in human cancer cells by modulation of Notch pathway elements suggest both tumor suppressive and oncogenic roles of Notch. These controversies may originate from our inadequate understanding of the regulation of Notch signaling under versatile genetic contexts, and reflect the multifaceted and pleiotropic roles of Notch in regulating different aspects of prostate cancer cell biology, such as proliferation, metastasis, and chemo-resistance. Future comprehensive studies using various mouse models for prostate cancer may help clarify the role of Notch signaling in prostate cancer and provide a solid basis for determining whether and how Notch should be employed as a therapeutic target for prostate cancer.

Notch signaling dynamics in the adult healthy prostate and in prostatic tumor development

BACKGROUND

The Notch signaling pathway has been implicated in prostate development, maintenance and tumorigenesis by its key role in cell-fate determination, differentiation and proliferation. Therefore, we proposed to analyze Notch family members transcription and expression, including ligands (Dll1, 3, 4 and Jagged1 and 2), receptors (Notch1-4) and effectors (Hes1, 2, 5 and Hey1, 2, L), in both normal and tumor bearing mouse prostates to better understand the dynamics of Notch signaling in prostate tumorigenesis.

METHODS

Wild type mice and transgenic adenocarcinoma of the mouse prostate model (TRAMP) mice were sacrificed at 18, 24 or 30 weeks of age and the prostates collected and processed for either whole prostate or prostate cell specific populations mRNA analysis and for protein expression analysis by immunohistochemistry and immunofluorescence.

RESULTS

We observed that Dll1 and Dll4 are expressed in the luminal compartment of the mouse healthy prostate, whereas Jagged2 expression is restricted to the basal and stromal compartment. Additionally, Notch2 and Notch4 are normally expressed in the prostate luminal compartment while Notch2 and Notch3 are also expressed in the stromal layer of the healthy prostate. As prostate tumor development takes place, there is up-regulation of Notch components. Particularly, the prostate tumor lesions have increased expression of Jagged1 and 2, of Notch3 and of Hey1. We have also detected the presence of activated Notch3 in prostatic tumors that co-express Jagged1 and ultimately the Hey1 effector.

CONCLUSIONS

Taken together our results point out the Notch axis Jagged1-2/Notch3/Hey1 to be important for prostate tumor development and worthy of additional functional studies and validation in human clinical disease.

Hes1 triggers epithelial-mesenchymal transition (EMT)-like cellular marker alterations and promotes invasion and metastasis of nasopharyngeal carcinoma by activating the PTEN/AKT pathway

Overexpression of the transcriptional factor Hes1 (hairy and enhancer of split-1) has been observed in numerous cancers, but the precise roles of Hes1 in epithelial-mesenchymal transition (EMT), cancer invasion and metastasis remain unknown. Our current study firstly revealed that Hes1 upregulation in a cohort of human nasopharyngeal carcinoma (NPC) biopsies is significantly associated with the EMT, invasive and metastatic phenotypes of cancer. In the present study, we found that Hes1 overexpression triggered EMT-like cellular marker alterations of NPC cells, whereas knockdown of Hes1 through shRNA reversed the EMT-like phenotypes, as strongly supported by Hes1-mediated EMT in NPC clinical specimens described above. Gain-of-function and loss-of-function experiments demonstrated that Hes1 promoted the migration and invasion of NPC cells in vitro. In addition, exogenous expression of Hes1 significantly enhanced the metastatic ability of NPC cells in vivo. Chromatin immunoprecipitation (ChIP) assays showed that Hes1 inhibited PTEN expression in NPC cells through binding to PTEN promoter region. Increased Hes1 expression and decreased PTEN expression were also observed in a cohort of NPC biopsies. Additional studies demonstrated that Hes1-induced EMT-like molecular changes and increased motility and invasion of NPC cells were mediated by PTEN. Taken together, our results suggest, for what we believe is the first time, that Hes1 plays an important role in the invasion and metastasis of NPC through inhibiting PTEN expression to trigger EMT-like phenotypes.

Hes1 triggers epithelial-mesenchymal transition (EMT)-like cellular marker alterations and promotes invasion and metastasis of nasopharyngeal carcinoma by activating the PTEN/AKT pathway

Overexpression of the transcriptional factor Hes1 (hairy and enhancer of split-1) has been observed in numerous cancers, but the precise roles of Hes1 in epithelial-mesenchymal transition (EMT), cancer invasion and metastasis remain unknown. Our current study firstly revealed that Hes1 upregulation in a cohort of human nasopharyngeal carcinoma (NPC) biopsies is significantly associated with the EMT, invasive and metastatic phenotypes of cancer. In the present study, we found that Hes1 overexpression triggered EMT-like cellular marker alterations of NPC cells, whereas knockdown of Hes1 through shRNA reversed the EMT-like phenotypes, as strongly supported by Hes1-mediated EMT in NPC clinical specimens described above. Gain-of-function and loss-of-function experiments demonstrated that Hes1 promoted the migration and invasion of NPC cells in vitro. In addition, exogenous expression of Hes1 significantly enhanced the metastatic ability of NPC cells in vivo. Chromatin immunoprecipitation (ChIP) assays showed that Hes1 inhibited PTEN expression in NPC cells through binding to PTEN promoter region. Increased Hes1 expression and decreased PTEN expression were also observed in a cohort of NPC biopsies. Additional studies demonstrated that Hes1-induced EMT-like molecular changes and increased motility and invasion of NPC cells were mediated by PTEN. Taken together, our results suggest, for what we believe is the first time, that Hes1 plays an important role in the invasion and metastasis of NPC through inhibiting PTEN expression to trigger EMT-like phenotypes.

Hes1 triggers epithelial-mesenchymal transition (EMT)-like cellular marker alterations and promotes invasion and metastasis of nasopharyngeal carcinoma by activating the PTEN/AKT pathway

Overexpression of the transcriptional factor Hes1 (hairy and enhancer of split-1) has been observed in numerous cancers, but the precise roles of Hes1 in epithelial-mesenchymal transition (EMT), cancer invasion and metastasis remain unknown. Our current study firstly revealed that Hes1 upregulation in a cohort of human nasopharyngeal carcinoma (NPC) biopsies is significantly associated with the EMT, invasive and metastatic phenotypes of cancer. In the present study, we found that Hes1 overexpression triggered EMT-like cellular marker alterations of NPC cells, whereas knockdown of Hes1 through shRNA reversed the EMT-like phenotypes, as strongly supported by Hes1-mediated EMT in NPC clinical specimens described above. Gain-of-function and loss-of-function experiments demonstrated that Hes1 promoted the migration and invasion of NPC cells in vitro. In addition, exogenous expression of Hes1 significantly enhanced the metastatic ability of NPC cells in vivo. Chromatin immunoprecipitation (ChIP) assays showed that Hes1 inhibited PTEN expression in NPC cells through binding to PTEN promoter region. Increased Hes1 expression and decreased PTEN expression were also observed in a cohort of NPC biopsies. Additional studies demonstrated that Hes1-induced EMT-like molecular changes and increased motility and invasion of NPC cells were mediated by PTEN. Taken together, our results suggest, for what we believe is the first time, that Hes1 plays an important role in the invasion and metastasis of NPC through inhibiting PTEN expression to trigger EMT-like phenotypes.

Characterization of Notch Signalling Pathway Members in Normal Prostate, Prostatic Intraepithelial Neoplasia (PIN) and Prostatic Adenocarcinoma

Prostate Cancer (PCa) holds the second place in terms of cancer-related mortality rate among men. The Notch signalling pathway regulates the proliferation and differentiation in embryonic and adult tissues and determines the cell fate. The body of knowledge in the present literature is currently controversial about the effect of the Notch pathway on prostatic cancer. Therefore, the present study aimed to examine the immunolocalization and expression levels of Notch1-4, Jagged1-2, Delta, HES1 and HES5 from among the members of the Notch signalling pathway in tissues of normal, prostatic intraepithelial neoplasia (PIN) and malignant prostate. The current study included a sample of 20 patients with localised prostatic adenocarcinoma, 18 patients with high grade PIN (H-PIN) and 18 normal prostatic tissue. Immunolocalisations of Notch1, 2, 3, 4, Jagged1, 2, Delta, HES1 and HES5 were identified through the immunohistochemical method. The findings of the present study showed that all in-scope members of the Notch signalling pathway were localised in PIN structures to a greater extent than in other tissues and from amongst these members, specifically Notch1, Notch4, Jagged1 and HES1 were at more significant levels. Consequently, the findings of the present study may indicate that the Notch signalling pathway can play a role especially in the formation of PIN structures.

In vitro effects of phenytoin and DAPT on MDA-MB-231 breast cancer cells

Voltage-gated sodium channel (VGSC) activity enhances cell behaviors related to metastasis, such as motility, invasion, and oncogene expression. Neonatal alternative splice form of Nav1.5 isoform is expressed in metastatic breast cancers. Furthermore, aberrant Notch signaling pathway can induce oncogenesis and may promote the progression of breast cancers. In this study, we aimed to analyze the effect of the nNav1.5 inhibitor phenytoin and Notch signal inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine-t-butyl ester (DAPT) on triple negative breast cancer cell line (MDA-MB-231) via inhibition of nNav1.5 VGSC activity and Notch signaling, respectively. In order to determine the individual and combined effects of these inhibitors, the 4-[3-(4-iyodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1) test, wound healing assay, and zymography were performed to detect the proliferation, lateral motility, and matrix metalloproteinase-9 (MMP9) activity, respectively. The expressions of nNav1.5, Notch4, MMP9, and tissue inhibitor of metalloproteinases-1 (TIMP1) were also detected by quantitative real-time reverse transcriptase-polymerase chain reaction. DAPT caused an antiproliferative effect when the doses were higher than 10 µM, whereas phenytoin showed no inhibitory action either alone or in combination with DAPT on the MDA-MB-231 cells. Furthermore, it was found that the lateral motility was inhibited by both inhibitors; however, this inhibitory effect was partially rescued when they were used in combination. Meanwhile, the results showed that the MMP9 activity and the ratio of MMP9 mRNA to TIMP1 mRNA were only decreased by DAPT. Thus, we conclude that the combined effect of DAPT and phenytoin is not as beneficial as using DAPT alone on MDA-MB-231 breast cancer cells.

The role of notch signaling in bone marrow niche

OBJECTIVE

Bone marrow (BM) niche is a three-dimensional structure composed of a series of cells and it is one of the most controversial topics in hematological malignancies, leukemia, and even metastasis. Here, we review the relationship between Notch signaling and different fates of stem cells and other BM niche cells.

METHODS

Relevant English-language literature were searched and retrieved from PubMed (2000-2013) using the terms Notch signaling, BM niche, and microRNAs (miRNAs).

DISCUSSION

Notch signaling pathway is a signaling system involved in cellular processes such as proliferation, differentiation, and apoptosis. The notch signaling pathway components are associated with interaction between leukemic, metastatic, and normal cells and their microenvironment. miRNAs play an important role in expression and regulation of signaling molecules. It is necessary to evaluate the relationship between aberrant miRNA expression and notch signaling such as miR-128 and miR-30 in glioma and angiogenesis with notch signaling, respectively.

CONCLUSIONS

Characterizing malignant cells and future studies focus on better understanding the variety of cancers and apoptosis with activated Notch signaling pathway, may remain promising this signaling system as a safe and effective therapeutic target.

Androgen receptor promotes the oncogenic function of overexpressed Jagged1 in prostate cancer by enhancing cyclin B1 expression via Akt phosphorylation

The Jagged1, a Notch signaling pathway ligand, had been shown to have a positive correlation with prostate cancer development. Our study for Jagged1 expression in 218 prostate cancer tissue samples also supports this conclusion. However, the detailed molecular mechanism of Jagged1 in promoting the progression of prostate cancer is still unclear. Through cell proliferation examination, androgen receptor (AR) was found to promote the oncogenic function of Jagged1 to enhance the cell proliferation rate by comparing four prostate cancer cell lines, LNCaP, LAPC4, DU145, and PC3, which was further validated through analyzing the survival of 118 patients treated with androgen-deprivation therapy (ADT) with different expression levels of Jagged1 and AR. More importantly, our data showed that Jagged1 combined with AR could increase the phosphorylation level of Akt and, in turn, phosphorylated Akt plays an important role in regulating the expression level of cyclin B1 by interacting with AR and increasing the transcriptional activity of AR. These data indicate that prostate cancer progression regulated by Jagged1 can be dramatically enhanced by combining with AR through promoting Akt activity.

IMPLICATIONS

This study could benefit our clinical treatments for patients with prostate cancer with overexpressed Jagged1 by targeting AR and Akt.

Activation of Notch signaling by short-term treatment with Jagged-1 enhances store-operated Ca(2+) entry in human pulmonary arterial smooth muscle cells

Notch signaling plays a critical role in controlling proliferation and differentiation of pulmonary arterial smooth muscle cells (PASMC). Upregulated Notch ligands and Notch3 receptors in PASMC have been reported to promote the development of pulmonary vascular remodeling in patients with pulmonary arterial hypertension (PAH) and in animals with experimental pulmonary hypertension. Activation of Notch receptors by their ligands leads to the cleavage of the Notch intracellular domain (NICD) to the cytosol by γ-secretase; NICD then translocates into the nucleus to regulate gene transcription. In this study, we examined whether short-term activation of Notch functionally regulates store-operated Ca(2+) entry (SOCE) in human PASMC. Treatment of PASMC with the active fragment of human Jagged-1 protein (Jag-1) for 15-60 min significantly increased the amplitude of SOCE induced by passive deletion of Ca(2+) from the intracellular stores, the sarcoplasmic reticulum (SR). The Jag-1-induced enhancement of SOCE was time dependent: the amplitude was maximized at 30 min of treatment with Jag-1, which was closely correlated with the time course of Jag-1-mediated increase in NICD protein level. The scrambled peptide of Jag-1 active fragment had no effect on SOCE. Inhibition of γ-secretase by N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT) significantly attenuated the Jag-1-induced augmentation of SOCE. In addition to the short-term effect, prolonged treatment of PASMC with Jag-1 for 48 h also markedly enhanced the amplitude of SOCE. These data demonstrate that short-term activation of Notch signaling enhances SOCE in PASMC; the NICD-mediated functional interaction with store-operated Ca(2+) channels (SOC) may be involved in the Jag-1-mediated enhancement of SOCE in human PASMC.

Elevated expression of notch1 is associated with metastasis of human malignancies

The expression level of Notch1 has been studied in many primary tumor types, but has not been widely investigated in metastatic lesions from human malignancies. Using immunohistochemistry (IHC), the expression level of Notch1 was evaluated and compared between primary and metastatic tumors in 12 different cancers. The mean IHC score of Notch1 was significantly increased in metastatic hepatocellular carcinoma (HCC; 5.4 ± 0.7) and in metastatic renal cell carcinoma (RCC; 5.0 ± 2.3) compared with primary HCC (3.1 ± 0.7, P = .035) and RCC (1.3 ± 0.6, P = .049), respectively. Similarly, the expression level of Notch1 showed an increasing trend in the metastatic malignancies in the larynx, prostate, and stomach compared with corresponding primary malignancies (P values are .055, .072, and .074, respectively). The results demonstrate elevated expression of Notch1 in some metastatic tumors, suggesting that Notch1 may play an important role in the development or maintenance of metastatic lesions, and targeting of Notch1 might be a therapeutic approach against tumor metastasis.

Hypoxia, notch signalling, and prostate cancer

The notch signalling pathway is involved in differentiation, proliferation, angiogenesis, vascular remodelling, and apoptosis. Deregulated expression of notch receptors, ligands, and targets is observed in many solid tumours, including prostate cancer. Hypoxia is a common feature of prostate tumours, leading to increased gene instability, reduced treatment response, and increased tumour aggressiveness. The notch signalling pathway is known to regulate vascular cell fate and is responsive to hypoxia-inducible factors. Evidence to date suggests similar, therapeutically exploitable, behaviour of notch-activated and hypoxic prostate cancer cells.

Silencing Notch-1 induces apoptosis and increases the chemosensitivity of prostate cancer cells to docetaxel through Bcl-2 and Bax

Although docetaxel-based chemotherapy is therapeutically efficacious, drug resistance often leads to treatment failure in castration-resistant prostate cancer patients. The Notch signaling pathway plays a key role in prostate development and prostate cancer. We investigated whether silencing Notch-1 has therapeutic potential for the treatment of prostate cancer. To determine this, we performed cell and molecular analyses following the silencing of the Notch-1 gene in PC-3 castration-resistant prostate cancer cells using small interfering RNA. The results demonstrated that silencing the Notch-1 gene effectively inhibits proliferation and induces apoptosis in PC-3 cells. In addition, docetaxel treatment results in decreased proliferation and increased apoptosis in the Notch-1-silenced cells compared to the control PC-3 cells. Docetaxel treatment was also accompanied by an upregulation of Bax and a downregulation of Bcl-2. Thus, Notch-1 silencing downregulates the anti-apoptotic protein Bcl-2, and upregulates the pro-apoptotic protein Bax, which ultimately results in increased sensitivity of PC-3 cells to docetaxel. Taken together, these results suggest that Notch-1 is potentially an effective target for treating castration-resistant prostate cancer.

Notch activation by phenethyl isothiocyanate attenuates its inhibitory effect on prostate cancer cell migration

Phenethyl isothiocyanate (PEITC) is a promising cancer chemopreventive component of edible cruciferous vegetables with in vivo efficacy against prostate cancer in experimental rodents. Cancer chemopreventive response to PEITC is characterized by its ability to inhibit multiple oncogenic signaling pathways, including nuclear factor-κB, Akt, and androgen receptor. The present study demonstrates, for the first time, that PEITC treatment activates Notch signaling in malignant as well as normal human prostate cells. Exposure of human prostate cancer cells (LNCaP, PC-3, and DU145) and a normal human prostate epithelial cell line (PrEC) to PEITC resulted in cleavage (active form) of Notch1 and Notch2, and increased transcriptional activity of Notch. In PC-3 and LNCaP cells, PEITC treatment caused induction of Notch ligands Jagged1 and Jagged2 (PC-3), overexpression of γ-secretase complex components Presenilin1 and Nicastrin (PC-3), nuclear enrichment of cleaved Notch2, and/or up-regulation of Notch1, Notch2, Jagged1, and/or Jagged2 mRNA. PEITC-induced apoptosis in LNCaP and PC-3 cells was significantly attenuated by RNA interference of Notch2, but not by pharmacological inhibition of Notch1. Inhibition of PC-3 and LNCaP cell migration resulting from PEITC exposure was significantly augmented by knockdown of Notch2 protein as well as pharmacological inhibition of Notch1 activation. Nuclear expression of cleaved Notch2 protein was significantly higher in PC-3 xenografts from PEITC-treated mice and dorsolateral prostates from PEITC-fed TRAMP mice compared with respective control. Because Notch signaling is implicated in epithelial-mesenchymal transition and metastasis, the present study suggests that anti-metastatic effect of PEITC may be augmented by a combination regimen involving a Notch inhibitor.

Down regulation of CSL activity inhibits cell proliferation in prostate and breast cancer cells

The Notch receptor pathway provides a paradigm for juxtacrine signaling pathways and controls stem cell function, developmental cell fate decisions, and cellular differentiation. The Notch pathway is constitutively activated in human cancers by chromosomal rearrangements, activating point mutations, or altered expression patterns. Therefore, the Notch pathway is the subject of chemotherapeutic intervention in a variety of human cancers. Notch receptor activation results in the gamma-secretase dependent proteolytic cleavage of the receptor to liberate the Notch intracellular domain that acts to mediate co-activator recruitment to the DNA binding transcription factor, CSL (CBF-1/RBP-Jκ, Su(H), Lag-1). Therapeutic targeting of the Notch pathway by gamma-secretase inhibitors prevents NICD production and regulates CSL-dependent transcriptional activity. To interrogate the loss of CSL activity in breast and prostate cancer cells, we used lentiviral-based shRNA knockdown of CSL. Knockdown of CSL expression was assessed by decreased DNA binding activity and resulted in decreased cell proliferation. In contrast, gamma-secretase inhibitor (GSI) treatment of these prostate and breast cancer cell lines resulted in minimal growth effects. PCR profiling of Notch pathway genes identified expression changes in few genes (Delta-like-1, Deltex-1, LMO2, and SH2D1A) after CSL knockdown. Consistent with differential effects of GSI on cell survival, GSI treatment failed to recapitulate the gene expression changes observed after CSL knockdown. Thus, CSL inhibition may provide a more effective mechanism to inhibit Notch-pathway dependent cancer cell proliferation as compared to GSI treatment.

Targeting Notch signalling by the conserved miR-8/200 microRNA family in development and cancer cells

A genetic screen in Drosophila uncovers miR-8 as an inhibitor of Notch-induced overgrowth, and identifies a conserved regulatory network comprising the Notch pathway, ZEB1 and this miRNA regulating metastasis and proliferation in flies and cancer cells. See also Brabletz et al in this issue.

Notch signalling is crucial for the correct development and growth of numerous organs and tissues, and when subverted it can cause cancer. Loss of miR-8/200 microRNAs (miRNAs) is commonly observed in advanced tumours and correlates with their invasion and acquisition of stem-like properties. Here, we show that this miRNA family controls Notch signalling activation in Drosophila and human cells. In an overexpression screen, we identified the Drosophila miR-8 as a potent inhibitor of Notch-induced overgrowth and tumour metastasis. Gain and loss of mir-8 provoked developmental defects reminiscent of impaired Notch signalling and we demonstrated that miR-8 directly inhibits Notch ligand Serrate. Likewise, miR-200c and miR-141 directly inhibited JAGGED1, impeding proliferation of human metastatic prostate cancer cells. It has been suggested that JAGGED1 may also be important for metastases. Although in metastatic cancer cells, JAGGED1 modestly regulated ZEB1, the miR-200c's target in invasion, studies in Drosophila revealed that only concurrent overexpression of Notch and Zfh1/ZEB1 induced tumour metastases. Together, these data define a new way to attenuate or boost Notch signalling that may have clinical interest.

Notch pathway inhibition significantly reduces rhabdomyosarcoma invasiveness and mobility in vitro

PURPOSE

Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children and can be divided into two main subtypes: embryonal and alveolar RMS. Patients with metastatic disease continue to have very poor prognosis although aggressive therapies and recurrences are common in advanced localized disease. The oncogenic potential of the Notch pathway has been established in some cancers of the adult and in some pediatric malignancies.

EXPERIMENTAL DESIGN

A real-time PCR assay was used to ascertain the expression of several Notch pathway components in a wide panel of RMS and cell lines. Four γ-secretase inhibitors (GSIs) were tested for pathway inhibition and the degree of inhibition was assessed by analysis of Hes1 and Hey1 expression. The putative effects of Notch pathway inhibition were evaluated by wound-healing, matrigel/transwell invasion, cell-cycle, and apoptosis assays.

RESULTS

The Notch pathway was widely expressed and activated in RMS and underwent substantial inhibition when treated with GSIs or transfected with a dominant negative form of MAML1. RMS cells showed a significant decrease in its mobility and invasiveness when the Notch pathway was properly inhibited; conversely, its inhibition had no noticeable effect on cell cycle or apoptosis.

CONCLUSION

Pharmacological or genetic blockage of the pathway significantly reduced invasiveness of RMS cell lines, thereby suggesting a possible role of the Notch pathway in the regulation of the metastatic process in RMS.

Human homolog of Drosophila Hairy and enhancer of split 1, Hes1, negatively regulates δ-catenin (CTNND2) expression in cooperation with E2F1 in prostate cancer

Background

Neuronal synaptic junction protein δ-catenin (CTNND2) is often overexpressed in prostatic adenocarcinomas but the mechanisms of its activation are unknown. To address this question, we studied the hypothesis that Hes1, human homolog of Drosophila Hairy and enhancer of split (Hes) 1, is a transcriptional repressor of δ-catenin expression and plays an important role in molecular carcinogenesis.

Results

We identified that, using a δ-catenin promoter reporter assay, Hes1, but not its inactive mutant, significantly repressed the upregulation of δ-catenin-luciferase activities induced by E2F1. Hes1 binds directly to the E-boxes on δ-catenin promoter and can reduce the expression of δ-catenin in prostate cancer cells. In prostate cancer CWR22-Rv1 and PC3 cell lines, which showed distinct δ-catenin overexpression, E2F1 and Hes1 expression pattern was altered. The suppression of Hes1 expression, either by γ-secretase inhibitors or by siRNA against Hes1, increased δ-catenin expression. γ-Secretase inhibition delayed S/G2-phase transition during cell cycle progression and induced cell shape changes to extend cellular processes in prostate cancer cells. In neuroendocrine prostate cancer mouse model derived allograft NE-10 tumors, δ-catenin showed an increased expression while Hes1 expression was diminished. Furthermore, E2F1 transcription was very high in subgroup of NE-10 tumors in which Hes1 still displayed residual expression, while its expression was only moderately increased in NE-10 tumors where Hes1 expression was completely suppressed.

Conclusion

These studies support coordinated regulation of δ-catenin expression by both the activating transcription factor E2F1 and repressive transcription factor Hes1 in prostate cancer progression.

Stemness markers characterize IGR-CaP1, a new cell line derived from primary epithelial prostate cancer

Deciphering molecular pathways involved in the early steps of prostate oncogenesis requires both in vitro and in vivo models derived from human primary tumors. However the few recognized models of human prostate epithelial cancer originate from metastases. To date, very few models are proposed from primary tumors and immortalizing normal human prostate cells does not recapitulate the natural history of the disease. By culturing human prostate primary tumor cells onto human epithelial extra-cellular matrix, we successfully selected a new prostate cancer cell line, IGR-CaP1, and clonally-derived subclones. IGR-CaP1 cells, that harbor a tetraploid karyotype, high telomerase activity and mutated TP53, rapidly induced subcutaneous xenografts in nude mice. Furthermore, IGR-CaP1 cell lines, all exhibiting negativity for the androgen receptor and PSA, express the specific prostate markers alpha-methylacyl-CoA racemase and a low level of the prostate-specific membrane antigen PSMA, along with the prostate basal epithelial markers CK5 and CK14. More importantly, these clones express high CD44, CD133, and CXCR4 levels associated with high expression of α2β1-integrin and Oct4 which are reported to be prostate cancer stemness markers. RT-PCR data also revealed high activation of the Sonic Hedgehog signalling pathway in these cells. Additionally, the IGR-CaP1 cells possess a 3D sphere-forming ability and a renewal capacity by maintaining their CSC potential after xenografting in mice. As a result, the hormone-independent IGR-CaP1 cellular clones exhibit the original features of both basal prostate tissue and cancer stemness. Tumorigenic IGR-CaP1 clones constitute invaluable human models for studying prostate cancer progression and drug assessment in vitro as well as in animals specifically for developing new therapeutic approaches targeting prostate cancer stem cells.

Pro-oncogenic and anti-oncogenic pathways: opportunities and challenges of cancer therapy

Carcinogenesis is the uncontrolled growth of cells gaining the potential to invade and disrupt vital tissue functions. This malignant process includes the occurrence of 'unwanted' gene mutations that induce the transformation of normal cells, for example, by overactivation of pro-oncogenic pathways and inactivation of tumor-suppressive or anti-oncogenic pathways. It is now recognized that the number of major signaling pathways that control oncogenesis is not unlimited; therefore, suppressing these pathways can conceivably lead to a cancer cure. However, the clinical application of cancer intervention has not matched up to scientific expectations. Increasing numbers of studies have revealed that many oncogenic-signaling elements show double faces, in which they can promote or suppress cancer pathogenesis depending on tissue type, cancer stage, gene dosage and their interaction with other players in carcinogenesis. This complexity of oncogenic signaling poses challenges to traditional cancer therapy and calls for considerable caution when designing an anticancer drug strategy. We propose future oncology interventions with the concept of integrative cancer therapy.

Notch-1 signaling is lost in prostate adenocarcinoma and promotes PTEN gene expression

Prostate tumorigenesis is associated with loss of PTEN gene expression. We and others have recently reported that PTEN is regulated by Notch-1 signaling. Herein, we tested the hypothesis that alterations of the Notch-1 signaling pathway are present in human prostate adenocarcinoma and that Notch-1 signaling regulates PTEN gene expression in prostate cells. Prostate adenocarcinoma cases were examined by immunohistochemistry for ligand cleaved (activated) Notch-1 protein. Tumor foci exhibited little cleaved Notch-1 protein, but expression was observed in benign tissue. Both tumor and benign tissue expressed total (uncleaved) Notch-1. Reduced Hey-1 expression was seen in tumor foci but not in benign tissue, confirming loss of Notch-1 signaling in prostate adenocarcinoma. Retroviral expression of constitutively active Notch-1 in human prostate tumor cell lines resulted in increased PTEN gene expression. Incubation of prostate cell lines with the Notch-1 ligand, Delta, resulted in increased PTEN expression indicating that endogenous Notch-1 regulates PTEN gene expression. Chromatin immunoprecipitation demonstrated that CBF-1 was bound to the PTEN promoter. These data collectively indicate that defects in Notch-1 signaling may play a role in human prostate tumor formation in part via a mechanism that involves regulation of the PTEN tumor suppressor gene.

Targeted knockdown of Notch1 inhibits invasion of human prostate cancer cells concomitant with inhibition of matrix metalloproteinase-9 and urokinase plasminogen activator

PURPOSE

Notch, a type 1 transmembrane protein, plays a key role in the development of many tissues and organ types. Aberrant Notch signaling, found in a wide variety of human cancers, contributes to tumor development. Because Notch1 was found to be overexpressed in prostate cancer (PCa) cells and human PCa tissue, we therefore tested our hypothesis that overexpression of Notch1 in PCa promotes tumor invasion.

EXPERIMENTAL DESIGN

Notch1 expression was evaluated in human PCa cells and human PCa tissues. PCa cells were transiently transfected with Notch1-specific small interfering RNAs in concentrations ranging from 30 to 120 nmol/L and subsequently evaluated for effects on invasion and expression analysis for molecules involved in invasion.

RESULTS

Small interfering RNA-mediated knockdown of Notch1 in PC3 and 22Rnu1 PCa cells dramatically decreased their invasion. Focused cDNA array revealed that Notch1 knockdown resulted in significant reduction in the expression of urokinase plasminogen activator (uPA) and matrix metalloproteinase-9 (MMP9) gene transcripts. These data were further verified by reverse transcription-PCR, real-time reverse transcription-PCR, and immunoblot analysis. Knockdown of Notch1 was also observed to significantly reduce the mRNA expression and protein levels of uPA and its receptor uPAR. A significant reduction in MMP9 expression in Notch1 knockdown cells suggested a role for Notch1 in augmenting MMP9 transcription.

CONCLUSIONS

Our data show the involvement of Notch1 in human PCa invasion and that silencing of Notch1 inhibits invasion of human PCa cells by inhibiting the expression of MMP9 and uPA. Thus, targeting of Notch1 could be an effective therapeutic approach against PCa.

The Notch pathway in prostate development and cancer

The Notch family of transmembrane receptors are important mediators of cell fate determination. Accordingly, Notch signaling is intimately involved in the development of numerous tissues. Recent findings have highlighted a critical role for Notch signaling in normal prostate development. Notch signaling is required for embryonic and postnatal prostatic growth and development, for proper cell lineage specification within the prostate, as well as for adult prostate maintenance and regeneration following castration and hormone replacement. Evidence for Notch as a regulator of prostate cancer development, progression, and metastasis has also emerged. This review summarizes our current understanding of the role of Notch pathway elements, including members of the Jagged, Delta-like, hairy/enhancer-of-split, and hairy/enhancer-of-split related with YRPW motif families, in prostate development and tumorigenesis. Data supporting Notch pathway elements as oncogenes and tumor suppressors in prostate tumors, as well as data implicating Notch receptors and ligands as potential markers of normal prostate stem/progenitor cells and prostate cancer stem/initiating cells, are also presented.

Gene expression profile of prostate cancer cell lines: effect of nerve growth factor treatment

A dysregulation of the nerve growth factor (NGF)-mediated control of prostate cell growth is associated with the malignant progression of prostate epithelial cells. Exogenous NGF induced in prostate cancer (PCa) cell lines DU145 and PC3 the expression of p75(NGFR), accompanied by a reduction of the cell malignancy. The aim of this study was to analyze the profile of NGF-regulated genes the PCa cell line DU145 by using the cDNA microarray technique. NGF treatment of DU145 cells decreased the expression of 52 known genes, while the expression of 40 known genes was increased. NGF treatment of the DU145 cell line modified the expression profile of clusters of genes involved in invasion and metastasis, in cell proliferation and apoptosis, inflammation, cell metabolism and transcriptional activity. Interestingly, NGF induced the same pattern of gene modifications in both PCa cell lines. Data presented here may help to identify gene/proteins that dispose to PCa progression and to assess future markers that could allow the development of new clinic diagnostic and therapeutical approaches.

Ion channels in death and differentiation of prostate cancer cells

Plasma membrane ion channels contribute to virtually all basic cellular processes, including such crucial ones for maintaining tissue homeostasis as proliferation, differentiation, and apoptosis. Enhanced proliferation, aberrant differentiation, and impaired ability to die are the prime reasons for abnormal tissue growth, which can eventually turn into uncontrolled expansion and invasion, characteristic of cancer. Prostate cancer (PCa) cells express a variety of plasma membrane ion channels. By providing the influx of essential signaling ions, perturbing intracellular ion concentrations, regulating cell volume, and maintaining membrane potential, PCa cells are critically involved in proliferation, differentiation, and apoptosis. PCa cells of varying metastatic ability can be distinguished by their ion channel characteristics. Increased malignancy and invasiveness of androgen-independent PCa cells is generally associated with the shift to a 'more excitable' phenotype of their plasma membrane. This shift is manifested by the appearance of voltage-gated Na(+) and Ca(2+) channels which contribute to their enhanced apoptotic resistance together with downregulated store-operated Ca(2+) influx, altered expression of different K(+) channels and members of the Transient Receptor Potential (TRP) channel family, and strengthened capability for maintaining volume constancy. The present review examines channel types expressed by PCa cells and their involvement in metastatic behaviors.