Expression and clinical significance of Notch receptors in human renal cell carcinoma

Notch signaling pathway in cancer: from mechanistic insights to targeted therapies

Notch signaling, renowned for its role in regulating cell fate, organ development, and tissue homeostasis across metazoans, is highly conserved throughout evolution. The Notch receptor and its ligands are transmembrane proteins containing epidermal growth factor-like repeat sequences, typically necessitating receptor-ligand interaction to initiate classical Notch signaling transduction. Accumulating evidence indicates that the Notch signaling pathway serves as both an oncogenic factor and a tumor suppressor in various cancer types. Dysregulation of this pathway promotes epithelial-mesenchymal transition and angiogenesis in malignancies, closely linked to cancer proliferation, invasion, and metastasis. Furthermore, the Notch signaling pathway contributes to maintaining stem-like properties in cancer cells, thereby enhancing cancer invasiveness. The regulatory role of the Notch signaling pathway in cancer metabolic reprogramming and the tumor microenvironment suggests its pivotal involvement in balancing oncogenic and tumor suppressive effects. Moreover, the Notch signaling pathway is implicated in conferring chemoresistance to tumor cells. Therefore, a comprehensive understanding of these biological processes is crucial for developing innovative therapeutic strategies targeting Notch signaling. This review focuses on the research progress of the Notch signaling pathway in cancers, providing in-depth insights into the potential mechanisms of Notch signaling regulation in the occurrence and progression of cancer. Additionally, the review summarizes pharmaceutical clinical trials targeting Notch signaling for cancer therapy, aiming to offer new insights into therapeutic strategies for human malignancies.

MAPK and Notch-Mediated Effects of Meso-Xanthin F199 Compounds on Proliferative Activity and Apoptosis of Human Melanocytes in Three-Dimensional Culture

Meso-Xanthin (Meso-Xanthin F199™) is a highly active antiaging injection drug of the latest generation. The main acting compound is fucoxanthin, supplemented with several growth factors, vitamins, and hyaluronic acid. Previous examination of fucoxanthin on melanocytes showed its ability to inhibit skin pigmentation through different signaling pathways focused on suppression of melanogenic-stimulating receptors. In turn, the anticancer property of fucoxanthin is realized through MAPK and PI3K pathways. We aimed to evaluate the effect of fucoxanthin and supplemented growth factors on melanocyte growth and transformation at a proteomic level. The effect of fucoxanthin on melanocytes cultivated in three-dimensional (3D) condition was examined using high-throughput proteomic and system biology approaches to disclose key molecular events of the targeted action. Our results demonstrated significant inhibition of cell differentiation and ubiquitination processes. We found that the negative regulation of PSME1 and PTGIS largely determines the inhibition of NF-κB and MAPK2. Besides, fucoxanthin selectively inhibits cell differentiation via negative regulation of Raf signaling and the upstream activation of IL-1 signaling. It is assumed that inhibition of Raf influences the Notch-4 signaling and switches off the MAPK/MAPK2 cascade. Blockage of MAPK/MAPK2 is feasible due to suppression of Ras and NF-κB by the addressed action of IKKB, IKK2, and TRAF6. Suggestively, Meso-Xanthin F199™ can manage processes of proliferative activity and inhibition of apoptosis due to composition of fucoxanthin and growth-stimulating factors, which may increase the risk of skin cancer development under certain condition.

Notch Signaling Pathway in Cancer-Review with Bioinformatic Analysis

Simple Summary

The Notch signaling pathway, which controls multiple cell differentiation processes during the embryonic stage and adult life, is associated with carcinogenesis and disease progression. The aim of the present study was to highlight cancer heterogeneity with respect to the Notch pathway. Our analysis concerns the effects of the Notch signaling at different levels, including core components and downstream target genes. We also demonstrate overall and disease-free survival results, pointing out the characteristics of particular Notch components. Depending on tissue context, Notch members can be either oncogenic or suppressive. We observed different expression profile core components and target genes that could be associated with distinct survival of patients. Advances in our understanding of the Notch signaling in cancer are very promising for the development of new treatment strategies for the benefit of patients.

Abstract

Notch signaling is an evolutionarily conserved pathway regulating normal embryonic development and homeostasis in a wide variety of tissues. It is also critically involved in carcinogenesis, as well as cancer progression. Activation of the Notch pathway members can be either oncogenic or suppressive, depending on tissue context. The present study is a comprehensive overview, extended with a bioinformatics analysis of TCGA cohorts, including breast, bladder, cervical, colon, kidney, lung, ovary, prostate and rectum carcinomas. We performed global expression profiling of the Notch pathway core components and downstream targets. For this purpose, we implemented the Uniform Manifold Approximation and Projection algorithm to reduce the dimensions. Furthermore, we determined the optimal cutpoint using Evaluate Cutpoint software to established disease-free and overall survival with respect to particular Notch members. Our results demonstrated separation between tumors and their corresponding normal tissue, as well as between tumors in general. The differentiation of the Notch pathway, at its various stages, in terms of expression and survival resulted in distinct profiles of biological processes such as proliferation, adhesion, apoptosis and epithelial to mesenchymal transition. In conclusion, whether oncogenic or suppressive, Notch signaling is proven to be associated with various types of malignancies, and thus may be of interest as a potential therapeutic target.

[Involvement of Notch1 and ALK4/5 Signaling Pathways in Renal Tubular Cell Death: Their Application to Clarification of Cadmium Toxicity]

Renal tubular cell death is caused by various extracellular stresses including toxic amounts of cadmium, an occupational and environmental pollutant metal, and is responsible for renal dysfunction. While cadmium exposure disrupts many intracellular signaling pathways, the molecular mechanism underlying cadmium-induced renal tubular cell death has not yet been fully elucidated. We have recently identified two important intracellular signaling pathways that promote cadmium-induced renal tubular cell death: the Notch1 signaling and activin receptor-like kinase (ALK) 4/5 signaling (also known as the activin-transforming growth factor β receptor pathways). In this review paper, we introduce our previous experimental findings, focusing on Notch1 and ALK4/5 signaling pathways, which may uncover the molecular mechanisms involved in cadmium-induced renal tubular cell death.

Tumor-educated B cells promote renal cancer metastasis via inducing the IL-1β/HIF-2α/Notch1 signals

While B cells in the tumor microenvironment (TME) might play important roles in cancer progression, their impacts on the renal cell carcinoma (RCC) metastasis remained unclear, which drew our attention to further explore. We found that RCC tissues could recruit more B cells than the surrounding normal renal tissues from human clinical RCC samples. Wound healing assay, transwell assay and 3D invasion assays demonstrated that recruited B cells, also known as tumor-educated B cells (TEB), could significantly increase the RCC cell migration and invasion. In addition, in vivo data from xenograft RCC mouse model also confirmed that TEB could enhance RCC cell invasive and metastatic capability. Mechanism dissection revealed that TEB activated IL-1β/HIF-2α signals in RCC cells that could induce the downstream Notch1 signaling pathway. The above results demonstrated the key roles of TEB within renal cancer associated tumor microenvironment were metastasis-promotor and might help us to develop the potential therapies via targeting these newly identified IL-1β/HIF-2α/Notch1 signals in RCC progression.

A three-molecule score based on Notch pathway predicts poor prognosis in non-metastasis clear cell renal cell carcinoma

We constructed a three-molecule score based on the expression of Notch pathway molecules: Jagged1, intracellular Notch1 (ICN1) and Hes1 (JIH score). To assess prognostic value of the JIH score in non-metastasis clear cell renal cell carcinoma (ccRCC), we identified 467 patients who underwent nephrectomy during 2008-2009 as our study population. Immunohistochemistry was used to evaluate the expression of these three molecules. Cox regression models were applied to construct the JIH score, while Kaplan-Meier methods, multivariate analyses and nomogram were used to explore prognostic value of the JIH score. Our result confirmed that JIH score was an independent prognosticator for both overall survival (OS) and recurrence-free survival (RFS). Survival analyses showed that a higher JIH score indicated worse clinical outcomes (JIH score 3: 58.3% and 58.0% for 6-year OS and RFS, respectively; JIH score 0: 96.7% and 91.6% for 6-year OS and RFS, respectively). Nomograms based on JIH score and other conventional clinicopathological features had a better capability in predicting patients with pT1 stage disease for both OS and RFS (84.6% and 83.9%, respectively). The JIH score is a novel prognosticator representing activation of Notch pathway for non-metastasis ccRCC, and raises an alternative strategy for excavating potential biomarkers for signal pathways.

Renal carcinoma/kidney progenitor cell chimera organoid as a novel tumorigenesis gene discovery model

Three-dimensional (3D) organoids provide a new way to model various diseases, including cancer. We made use of recently developed kidney-organ-primordia tissue-engineering technologies to create novel renal organoids for cancer gene discovery. We then tested whether our novel assays can be used to examine kidney cancer development. First, we identified the transcriptomic profiles of quiescent embryonic mouse metanephric mesenchyme (MM) and of MM in which the nephrogenesis program had been induced ex vivo. The transcriptome profiles were then compared to the profiles of tumor biopsies from renal cell carcinoma (RCC) patients, and control samples from the same kidneys. Certain signature genes were identified that correlated in the developmentally induced MM and RCC, including components of the caveolar-mediated endocytosis signaling pathway. An efficient siRNA-mediated knockdown (KD) of Bnip3, Gsn, Lgals3, Pax8, Cav1, Egfr or Itgb2 gene expression was achieved in mouse RCC (Renca) cells. The live-cell imaging analysis revealed inhibition of cell migration and cell viability in the gene-KD Renca cells in comparison to Renca controls. Upon siRNA treatment, the transwell invasion capacity of Renca cells was also inhibited. Finally, we mixed E11.5 MM with yellow fluorescent protein (YFP)-expressing Renca cells to establish chimera organoids. Strikingly, we found that the Bnip3-, Cav1- and Gsn-KD Renca-YFP+ cells as a chimera with the MM in 3D organoid rescued, in part, the RCC-mediated inhibition of the nephrogenesis program during epithelial tubules formation. Altogether, our research indicates that comparing renal ontogenesis control genes to the genes involved in kidney cancer may provide new growth-associated gene screens and that 3D RCC-MM chimera organoids can serve as a novel model with which to investigate the behavioral roles of cancer cells within the context of emergent complex tissue structures.

Editor’s Choice: Chimeras between embryonic kidney cells and renal carcinoma cells serve as a novel model to assay the roles of co-regulated genes in kidney development and renal carcinogenesis.

Downregulation of Notch4 - a prognostic marker in distinguishing oral verrucous carcinoma from oral squamous cell carcinoma

Introduction

Oral verrucous carcinoma is a special form of well-differentiated squamous cell carcinoma which possesses specific clinical, morphologic and cytokinetic features that differ from other types of oral cancers and hence diagnosis requires immense experience in histopathology. Hence it is certainly important to distinguish such a lesion from other oral tumors as treatment strategies vary widely between them.

Objective

In search of a critical diagnostic marker in distinguishing oral verrucous carcinoma from oral squamous cell carcinoma, Notch4 receptor, one of the key regulatory molecules of the Notch signaling family has been aberrantly activated in the progression of several types of tumors. However its function in oral verrucous carcinoma remains unexplored. Thus the present study aims in determining the differential expression pattern of Notch4 in oral verrucous carcinoma and oral squamous cell carcinoma.

Methods

Ten patients reported positive for oral cancer (5 patients with oral verrucous carcinoma and 5 patients with oral squamous cell carcinoma). Five normal tissue samples were also obtained and evaluated for clinicopathological parameters and immunohistochemistry, western blotting and real time polymerase chain reaction for Notch4 expression.

Results

Our results reveal that the expression of Notch4 was considerably high in oral squamous cell carcinoma lesions compared to normal tissue, whereas in oral verrucous carcinoma, irrespective of the clinicopathological features, complete regulação descendente of Notch4 was observed.

Conclusions

These preliminary findings strongly support the fact that Notch4 is downregulated in oral verrucous carcinoma and could be considered as a suitable prognostic marker in distinguishing oral verrucous carcinoma from oral squamous cell carcinoma. This distinguishing marker can help in improving therapeutic options in patients diagnosed with oral verrucous carcinoma.

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.

Tumor size, stage and grade alterations of urinary peptidome in RCC

Background

Several promising biomarkers have been found for RCC, but none of them has been used in clinical practice for predicting tumour progression. The most widely used features for predicting tumour aggressiveness still remain the cancer stage, size and grade. Therefore, the aim of our study is to investigate the urinary peptidome to search and identify peptides whose concentrations in urine are linked to tumour growth measure and clinical data.

Methods

A proteomic approach applied to ccRCC urinary peptidome (n = 117) based on prefractionation with activated magnetic beads followed by MALDI-TOF profiling was used. A systematic correlation study was performed on urinary peptide profiles obtained from MS analysis. Peptide identity was obtained by LC–ESI–MS/MS.

Results

Fifteen, twenty-six and five peptides showed a statistically significant alteration of their urinary concentration according to tumour size, pT and grade, respectively. Furthermore, 15 and 9 signals were observed to have urinary levels statistically modified in patients at different pT or grade values, even at very early stages. Among them, C1RL, A1AGx, ZAG2G, PGBM, MMP23, GP162, ADA19, G3P, RSPH3, DREB, NOTC2 SAFB2 and CC168 were identified.

Conclusions

We identified several peptides whose urinary abundance varied according to tumour size, stage and grade. Among them, several play a possible role in tumorigenesis, progression and aggressiveness. These results could be a useful starting point for future studies aimed at verifying their possible use in the managements of RCC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0693-8) contains supplementary material, which is available to authorized users.

Detrimental effects of Notch1 signaling activated by cadmium in renal proximal tubular epithelial cells

We examined the roles of Notch1 signaling and its cross-talk with other signaling pathways, including p53 and phosphatidylinositol-3-kinase (PI3K)/Akt, in cadmium-induced cellular damage in HK-2 human renal proximal tubular epithelial cells. Following exposure to cadmium chloride (CdCl2), the level of Notch intracellular domain (NICD), the cleaved form of the Notch1 receptor, was increased and accumulated in the nuclear fraction. Knockdown of Notch1 with siRNA or treatment with the γ-secretase inhibitor, DAPT (N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester), prevented CdCl2-induced morphological change of HK-2 cells and reduction of cell viability. Knockdown of Jagged1 or Jagged2, the ligands of the Notch1 receptor, partially suppressed cadmium cytotoxicity. Inhibition of p53 activity with pifithrin-α or inhibition of PI3K with LY294002 suppressed CdCl2-induced cellular damage and elevation of Notch1-NICD. In addition, treatment with the epidermal growth factor receptor (EGFR) inhibitor, AG1478, and the insulin-like growth factor-1 receptor inhibitor, PPP, suppressed both Notch1-NICD accumulation and Akt phosphorylation in HK-2 cells exposed to CdCl2. However, knockdown of Notch1 did not affect CdCl2-induced p53 accumulation and phosphorylation but suppressed phosphorylation of EGFR, Akt, and p70 S6 kinase. Depletion of Notch1 suppressed CdCl2-induced reduction of E-cadherin expression and elevation of Snail expression. Furthermore, treatment with SB216763, an inhibitor of glycogen synthase kinase-3, suppressed the potency of LY294002 treatment to reduce Snail expression in HK-2 cells exposed to CdCl2. Knockdown of Snail with siRNA partially prevented HK-2 cells from CdCl2-induced reduction of E-cadherin expression and cellular damage. These results suggest that cadmium exposure induces the activation of Notch1 signaling in renal proximal tubular cells with cooperative activation by the p53 and PI3K/Akt signaling pathways; the resultant expression of Snail, a repressor of E-cadherin expression, might lead to cellular damage by decreasing cell-cell adhesion.

DHH is an independent prognosticator of oncologic outcome of clear cell renal cell carcinoma

PURPOSE

Aberrant HH signaling has proved important in the pathogenesis of several solid cancers. Limited in vitro analyses suggested an oncogenic role for HH in renal cell carcinoma. In this explorative study we sought to validate aberrant HH expression in patients with renal cell carcinoma.

MATERIALS AND METHODS

A tissue microarray was constructed from 140 radical nephrectomy specimens of patients with clear cell renal cell carcinoma. We performed immunohistochemistry for Ki67 and HH pathway biomarkers, including PTCH1, Smo, SHH, IHH, DHH, Gli1, Gli2 and Gli3. Staining intensity was measured by automated image processing and related to tumor stage and grade. The impact of biomarker expression on cancer specific survival was determined by univariate and multivariate Cox regression analysis.

RESULTS

Gli3, PTCH1, DHH and SHH demonstrated markedly higher expression in high than in low grade tumors. Tumor stage was not associated with marker expression. On univariate analysis DHH expression, and tumor grade and stage were associated with cancer specific survival. Multivariate analysis revealed that DHH, grade and stage were independent predictors of cancer specific survival.

CONCLUSIONS

To our knowledge we report for the first time that a biomarker of the HH pathway is associated with adverse pathological features and poor disease outcomes in patients with clear cell renal cell carcinoma. DHH may serve as an independent predictor of cancer specific survival in clear cell renal cell carcinoma cases. This supports further evaluation of HH signaling to validate the pathway as a target for novel therapy.

Expression and clinical significance of RCDG1 in renal cell carcinoma: a novel renal cancer‑associated gene

Recently identified molecular tumor markers have numerous potential applications in the diagnosis, therapy and prognostic prediction of renal cell carcinoma (RCC). Through bioinformatics‑based screening approaches together with validation of western blot and immunohistochemical data, the present study identified a novel renal cancer‑associated gene, preliminarily named Renal Cancer Differentiation Gene 1 (RCDG1), originally known as chromosome 4 open reading frame 46 (C4orf46). RCDG1 expression was evaluated by western blot analysis of RCC and adjacent normal tissues, renal cancer cell lines and normal kidney HEK293T cells. Additionally, RCDG1 expression was assessed in 124 RCC paraffin sections, including 92 paired adjacent normal tissues, by immunohistochemistry. The results showed that RCDG1 was significantly downregulated in RCC tissues as compared with normal adjacent tissues (P<0.001), and the expression of RCDG1 in clear cell (cc) RCC tissues was significantly lower as compared with that of non‑ccRCC tissues (P=0.005). Furthermore, statistical analysis revealed RCDG1 expression was negatively correlated with the Fuhrman grade in ccRCC (P=0.008). A reduction in RCDG1 expression may be associated with the oncogenesis of RCC and the differentiation of ccRCC. Further studies may provide more information about the function of RCDG1 gene in RCC.

Inhibition of γ-secretase induces G2/M arrest and triggers apoptosis in renal cell carcinoma

The present study was performed to explore the effects of Notch pathway inhibition on the proliferation and apoptosis of renal carcinoma cells. The expression levels of Notch1 and Jagged1 were examined by western blot analysis and immunohistochemistry in pathologically identified clear cell renal cell carcinoma (RCC) and normal kidney tissues. Next, γ-secretase inhibitor was used to suppress the Notch pathway in renal carcinoma cell lines. The proliferation was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry analysis was performed to determine the apoptosis, as well as cell cycle alteration. The expression of Notch1 and Jagged1 proteins was detected to be higher in tumor tissues than in non-neoplastic tissues by western blot analysis. The positive staining rates of Notch1 and Jagged1 in clear cell RCC were higher than in normal kidney tissues [95.3 vs. 36.4% (P<0. 05); 93.0 vs. 42.4% (P<0.05), respectively]. The expression levels of Notch1 and Jagged1 were found to statistically correlate with tumor size, grade, TNM stage and disease relapse. The suppression of the Notch pathway was associated with cell proliferation inhibition, as well as induced G2/M phase cell cycle arrest and cell apoptosis. The Notch pathway may be important in oncogenesis of clear cell RCC and the γ-secretase inhibitor may be a potential agent for target therapy of RCC.

A bright single-cell resolution live imaging reporter of Notch signaling in the mouse

BACKGROUND

Live imaging provides an essential methodology for understanding complex and dynamic cell behaviors and their underlying molecular mechanisms. Genetically-encoded reporter expressing mouse strains are an important tool for use in live imaging experiments. Such reporter strains can be engineered by placing cis-regulatory elements of interest to direct the expression of desired reporter genes. If these cis-regulatory elements are downstream targets, and thus activated as a consequence of signaling pathway activation, such reporters can provide read-outs of the signaling status of a cell. The Notch signaling pathway is an evolutionary conserved pathway operating in multiple developmental processes as well as being the basis for several congenital diseases. The transcription factor CBF1 is a central evolutionarily conserved component of the Notch signaling pathway. It binds the active form of the Notch receptor (NICD) and subsequently binds to cis-regulatory regions (CBF1 binding sites) in the promoters of Notch responsive genes. In this way, CBF1 binding sites represent a good target for the design of a Notch signaling reporter.

RESULTS

To generate a single-cell resolution Notch signaling reporter, we used a CBF responsive element to direct the expression of a nuclear-localized fluorescent protein. To do this, we linked 4 copies of a consensus CBF1 binding site to the basal simian virus 40 (SV40) promoter, placed this cassette in front of a fluorescent protein fusion comprising human histone H2B linked to the yellow fluorescent protein (YFP) Venus, one of the brightest available YFPs. We used the CBF:H2B-Venus construct to generate both transgenic embryonic mouse stem (ES) cell lines and a strain of transgenic mice that would report Notch signaling activity.

CONCLUSION

By using multiple CBF1 binding sites together with a subcellular-localized, genetically-encoded fluorescent protein, H2B-Venus, we have generated a transgenic strain of mice that faithfully recapitulates Notch signaling at single-cell resolution. This is the first mouse reporter strain in which individual cells transducing a Notch signal can be visualized. The improved resolution of this reporter makes it ideal for live imaging developmental processes regulated by the Notch signaling pathway as well as a short-term lineage tracer of Notch expressing cells due to the perdurance of the fluorescent reporter. Taken together, the CBF:H2B-Venus mouse strain is a unique tool to study and understand the morphogenetic events regulated by the Notch signaling pathway.

Crossing paths in Human Renal Cell Carcinoma (hRCC)

Historically, cell-signaling pathways have been studied as the compilation of isolated elements into a unique cascade that transmits extracellular stimuli to the tumor cell nucleus. Today, growing evidence supports the fact that intracellular drivers of tumor progression do not flow in a single linear pathway, but disseminate into multiple intracellular pathways. An improved understanding of the complexity of cancer depends on the elucidation of the underlying regulatory networks at the cellular and intercellular levels and in their temporal dimension. The high complexity of the intracellular cascades causes the complete inhibition of the growth of one tumor cell to be very unlikely, except in cases in which the so-called “oncogene addiction” is known to be a clear trigger for tumor catastrophe, such as in the case of gastrointestinal stromal tumors or chronic myeloid leukemia. In other words, the separation and isolation of the driver from the passengers is required to improve accuracy in cancer treatment. This review will summarize the signaling pathway crossroads that govern renal cell carcinoma proliferation and the emerging understanding of how these pathways facilitate tumor escape. We outline the available evidence supporting the putative links between different signaling pathways and how they may influence tumor proliferation, differentiation, apoptosis, angiogenesis, metabolism and invasiveness. The conclusion is that tumor cells may generate their own crossroads/crosstalk among signaling pathways, thereby reducing their dependence on stimulation of their physiologic pathways.

Vitamin D3 triggers antitumor activity through targeting hedgehog signaling in human renal cell carcinoma

Human clear cell renal cell carcinoma (CCC) remains resistant to treatments despite the progress in targeted therapies. Several signaling pathways acting during renal development are reactivated during kidney tumorigenesis; this is the case of the sonic hedgehog (SHH)-Gli. Interestingly, the precursor of active vitamin D3 (VD3), cholecalciferol, has been demonstrated to be a strong inhibitor of SHH-Gli signaling. Here, we show the preclinical efficacy of cholecalciferol in CCC both in vitro and in vivo. A panel of CCC cell lines, tumors and normal corresponding tissues from CCC patients were used to evaluate the expression of the VD3 receptor and metabolizing enzymes and the effects of cholecalciferol treatment. Subsequently, xenografted mice were treated with cholecalciferol in a prophylactic or therapeutic manner; their response and the adverse effects were evaluated on the basis of weekly monitoring, followed by blood collection procedures and X-ray micro-computed tomography. VD3 receptor and metabolizing enzymes are dramatically decreased in human cell lines and tumors. Cholecalciferol decreases cell proliferation and increases cell death by inhibition of the SHH-Gli pathway. Xenografted mice treated with cholecalciferol exhibit absence of tumor development or substantial growth inhibition. The treatment was shown to be safe; it did not induce calcification or calcium reabsorption. These findings establish that, although VD3 receptors and metabolizing enzymes are absent in CCC, cholecalciferol supplementation is a strong tool to block the reactivation of SHH-Gli pathway in this pathology, leading ultimately to tumor regression. Cholecalciferol may have highly therapeutic potential in CCC.

High-level expression of Notch1 increased the risk of metastasis in T1 stage clear cell renal cell carcinoma

Background

Although metastasis of clear cell renal cell carcinoma (ccRCC) is basically observed in late stage tumors, T1 stage metastasis of ccRCC can also be found with no definite molecular cause resulting inappropriate selection of surgery method and poor prognosis. Notch signaling is a conserved, widely expressed signal pathway that mediates various cellular processes in normal development and tumorigenesis. This study aims to explore the potential role and mechanism of Notch signaling in the metastasis of T1 stage ccRCC.

Methodology/Principal Findings

The expression of Notch1 and Jagged1 were analyzed in tumor tissues and matched normal adjacent tissues obtained from 51 ccRCC patients. Compared to non-tumor tissues, Notch1 and Jagged1 expression was significantly elevated both in mRNA and protein levels in tumors. Tissue samples of localized and metastatic tumors were divided into three groups based on their tumor stages and the relative mRNA expression of Notch1 and Jagged1 were analyzed. Compared to localized tumors, Notch1 expression was significantly elevated in metastatic tumors in T1 stage while Jagged1 expression was not statistically different between localized and metastatic tumors of all stages. The average size of metastatic tumors was significantly larger than localized tumors in T1 stage ccRCC and the elevated expression of Notch1 was significantly positive correlated with the tumor diameter. The functional significance of Notch signaling was studied by transfection of 786-O, Caki-1 and HKC cell lines with full-length expression plasmids of Notch1 and Jagged1. Compared to the corresponding controls, all cell lines demonstrated significant promotion in cell proliferation and migration while cell cycle remained unaffected.

Conclusions/Significance

High-level expression of Notch signaling increased the risk of metastasis in T1 stage ccRCC by stimulating the proliferation and migration of tumor cells, which may be helpful for the selection of suitable operation method and prognosis of ccRCC.

Notch in the kidney: development and disease

Notch signalling is a highly conserved cell-cell communication mechanism that regulates development, tissue homeostasis, and repair. Within the kidney, Notch has an important function in orchestrating kidney development. Recent studies indicate that Notch plays a key role in establishing proximal epithelial fate during nephron segmentation as well as the differentiation of principal cells in the renal collecting system. Notch signalling is markedly reduced in the adult kidney; however, increased Notch signalling has been noted in both acute and chronic kidney injury. Increased glomerular epithelial Notch signalling has been associated with albuminuria and glomerulosclerosis, while tubular epithelial Notch activation caused fibrosis development most likely inducing an improper epithelial repair pathway. Recent studies thereby indicate that Notch is a key regulator of kidney development, repair, and injury.

Notch signaling proteins: legitimate targets for cancer therapy

Proteins and small peptides (growth factors and hormones) are key molecules in maintaining cellular homeostasis. To that end, Notch signaling pathway proteins are known to play critical roles in maintaining the balance between cell proliferation, differentiation and apoptosis, and thus it has been suggested that Notch may be responsible for the development and progression of human malignancies. Therefore, the Notch signaling pathway proteins may present novel therapeutic targets, which could have promising therapeutic impact on eradicating human malignancies. This review describes the role of Notch signaling pathway proteins in cancer and how its deregulation is involved in tumor development and progression leading to metastasis and the ultimate demise of patients diagnosed with cancer. Further, we summarize the role of several Notch inhibitors especially "natural agents" that could represent novel therapeutic strategies targeting Notch signaling toward better treatment outcome of patients diagnosed with cancer.

Age-related properties of the tumour vasculature in renal cell carcinoma

OBJECTIVE

To assess whether ageing processes influence angiogenesis in renal cell carcinoma (RCC) we carried out a pilot study of vascular properties in a series of archival primary kidney tumours in patients of different ages.

PATIENTS AND METHODS

A cohort of patients with RCC was identified restrospectively, with an age range of 35-84 years. Paraffin-embedded, formalin-fixed sections of surgical tumour specimens were stained for endothelial (CD31, von Willebrand factor [vWF]), pericyte (alpha smooth muscle actin [SMA]) and leucocytic (CD45) markers, as well as for proliferative (Ki67) and angiogenic activity (tumour endothelial markers [TEMs], delta-like 4 [Dll4], Dll1, endothelial nitric oxide synthase [eNOS]). Vascular properties were compared between patients above and below 65 years of age.

RESULTS

Microvascular density (MVD) within capillary hot spots was generally higher in patients with non-metastatic clear-cell RCC (ccRCC; n = 21) than in those with metastatic RCC (mRCC; n= 9). Patients with ccRCC who were more than 65 years old showed significantly higher MVD than their younger (< 65 years) counterparts. There were dividing (Ki67-positive) endothelial and mural cells in both small (< 20 µm) capillary and large (> 20 µm), pre-capillary vessels, suggesting the involvement of both angiogenic and remodelling/arteriogenic processes. Tumour endothelial markers (TEM1, TEM7, TEM8), Notch ligands (Dll1, Dll4), and other molecular characteristics (eNOS) were analysed. Age-related differences were observed in the frequency of pre-capillary vessels expressing Dll1, which was significantly higher in tumours of younger patients (< 65 years), while eNOS was more prevalent among capillaries associated with ccRCC in older patients (>6 5 years).

CONCLUSIONS

The results of the present study suggest that age influences the structural and molecular properties of the tumour vasculature in ccRCC. We postulate that vascular ageing could also be relevant in the context of anti-angiogenic therapy.

Reduced Notch signaling leads to renal cysts and papillary microadenomas

The formation of proximal nephron segments requires canonical Notch2 signaling, but other functions of Notch signaling during renal development are incompletely understood. Here, we report that proximal tubules forming with reduced Notch signaling, resulting from delayed conditional inactivation of Notch1 and/or Notch2, are prone to cyst formation and tubular epithelial stratification. Conditional inactivation of the DNA binding factor RBP-J, which mediates Notch signaling, also resulted in multiple congenital cysts arising from the proximal tubule. Moreover, a few stratified foci/microadenomas containing hyperproliferative cells, resembling precursors of papillary renal cell carcinoma, formed in these proximal tubules. Epithelial stratification correlated neither with reduced expression of the transcriptional regulator of ciliary proteins TCF2/HNF1beta nor with loss of apical-basal polarity. Instead, Notch signaling helped to restrict the orientation of epithelial mitotic spindles to a plane parallel to the basement membrane during nephron elongation. In the absence of Notch, random spindle orientation may explain the epithelial stratification and cyst formation. Furthermore, post hoc analysis of human class 1 papillary renal cell carcinoma revealed reduced Notch activity in these tumors, resulting from abundant expression of a potent inhibitor of canonical Notch signaling, KyoT3/FHL1B. In summary, these data suggest that canonical Notch signaling maintains the alignment of cell division in the proximal tubules during nephrogenesis and that perturbations in Notch signaling may lead to cystic renal disease and tumorigenesis.