Evidence of the cross talk between Wnt and Notch signaling pathways in non-small-cell lung cancer (NSCLC): Notch3-siRNA weakens the effect of LiCl on the cell cycle of NSCLC cell lines

Investigating regulated signaling pathways in therapeutic targeting of non-small cell lung carcinoma

Non-small cell lung carcinoma (NSCLC) is the most common malignancy worldwide. The signaling cascades are stimulated via genetic modifications in upstream signaling molecules, which affect apoptotic, proliferative, and differentiation pathways. Dysregulation of these signaling cascades causes cancer-initiating cell proliferation, cancer development, and drug resistance. Numerous efforts in the treatment of NSCLC have been undertaken in the past few decades, enhancing our understanding of the mechanisms of cancer development and moving forward to develop effective therapeutic approaches. Modifications of transcription factors and connected pathways are utilized to develop new treatment options for NSCLC. Developing designed inhibitors targeting specific cellular signaling pathways in tumor progression has been recommended for the therapeutic management of NSCLC. This comprehensive review provided deeper mechanistic insights into the molecular mechanism of action of various signaling molecules and their targeting in the clinical management of NSCLC.

The emerging role of NOTCH3 receptor signalling in human lung diseases

The mammalian respiratory system or lung is a tree-like branching structure, and the main site of gas exchange with the external environment. Structurally, the lung is broadly classified into the proximal (or conducting) airways and the distal alveolar region, where the gas exchange occurs. In parallel with the respiratory tree, the pulmonary vasculature starts with large pulmonary arteries that subdivide rapidly ending in capillaries adjacent to alveolar structures to enable gas exchange. The NOTCH signalling pathway plays an important role in lung development, differentiation and regeneration post-injury. Signalling via the NOTCH pathway is mediated through activation of four NOTCH receptors (NOTCH1-4), with each receptor capable of regulating unique biological processes. Dysregulation of the NOTCH pathway has been associated with development and pathophysiology of multiple adult acute and chronic lung diseases. This includes accumulating evidence that alteration of NOTCH3 signalling plays an important role in the development and pathogenesis of chronic obstructive pulmonary disease, lung cancer, asthma, idiopathic pulmonary fibrosis and pulmonary arterial hypertension. Herein, we provide a comprehensive summary of the role of NOTCH3 signalling in regulating repair/regeneration of the adult lung, its association with development of lung disease and potential therapeutic strategies to target its signalling activity.

The Role of Notch3 Signaling in Cancer Stemness and Chemoresistance: Molecular Mechanisms and Targeting Strategies

Aberrant Notch signaling profoundly affects cancer progression. Especially the Notch3 receptor was found to be dysregulated in cancer, where its expression is correlated with worse clinicopathological features and poor prognosis. The activation of Notch3 signaling is closely related to the activation of cancer stem cells (CSCs), a small subpopulation in cancer that is responsible for cancer progression. In addition, Notch3 signaling also contributes to tumor chemoresistance against several drugs, including doxorubicin, platinum, taxane, epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitors (TKIs) and gemcitabine, through complex mechanisms. In this review, we mainly focus on discussing the molecular mechanisms by which Notch3 modulates cancer stemness and chemoresistance, as well as other cancer behaviors including metastasis and angiogenesis. What’s more, we propose potential treatment strategies to block Notch3 signaling, such as non-coding RNAs, antibodies and antibody-drug conjugates, providing a comprehensive reference for research on precise targeted cancer therapy.

GSK3β rephosphorylation rescues ALPL deficiency-induced impairment of odontoblastic differentiation of DPSCs

Background

Premature exfoliation of the deciduous teeth is a common manifestation in childhood patients with hypophosphatasia (HPP), which is an autosomal inherited disease caused by ALPL mutations. Dysplasia of the cementum, dentin, and alveolar bone has been proposed to be the main reasons for the exfoliation of teeth, while the extraordinarily complex intracellular mechanisms remain elusive. Dental pulp stem cells (DPSCs) have been demonstrated to successfully regenerate functional pulp-dentin-like tissue. Dental pulp cells derived from HPP patients impaired mineralization; however, insight into the deeper mechanism is still unclear.

Methods

The effects of ALPL on odontoblastic differentiation of DPSCs from HPP patient were assessed by Alizarin Red staining, immunofluorescent staining, Western blot and RT-PCR, and micro-CT assays.

Result

Here, we found DPSCs from HPP patient exhibited low ALP activity and impaired odontoblastic differentiation. Meanwhile, we found that loss of function of ALPL reduced phosphorylation of GSK3β in DPSCs. While GSK3β rephosphorylation improved odontoblastic differentiation of HPP DPSCs with LiCl treatment. Finally, we demonstrated systemic LiCl injection ameliorated tooth-associated defects in ALPL^+/− mice by enhanced phosphorylation of GSK3β in the teeth.

Conclusions

Our study indicates that ALPL regulates odontoblastic differentiation of DPSCs and provides useful information for understanding how ALPL deficiency led to tooth dysplasia and, ultimately, may inform efforts at improvement tooth defects in HPP patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02235-7.

The interaction of Notch and Wnt signaling pathways in vertebrate regeneration

Regeneration is an evolutionarily conserved process in animal kingdoms, however, the regenerative capacities differ from species and organ/tissues. Mammals possess very limited regenerative potential to replace damaged organs, whereas non-mammalian species usually have impressive abilities to regenerate organs. The regeneration process requires proper spatiotemporal regulation from key signaling pathways. The canonical Notch and Wnt signaling pathways, two fundamental signals guiding animal development, have been demonstrated to play significant roles in the regeneration of vertebrates. In recent years, increasing evidence has implicated the cross-talking between Notch and Wnt signals during organ regeneration. In this review, we summarize the roles of Notch signaling and Wnt signaling during several representative organ regenerative events, emphasizing the functions and molecular bases of their interplay in these processes, shedding light on utilizing these two signaling pathways to enhance regeneration in mammals and design legitimate therapeutic strategies.

Evodiamine suppresses Notch3 signaling in lung tumorigenesis via direct binding to γ-secretases

BACKGROUND

Notch activation requires proteolytic cleavage of the receptor by γ-secretase protein complex. Inhibition of Notch receptor activation (e.g. Notch3) with γ-secretase inhibitor is a potential new therapeutic approach for the targeted therapy of non-small cell lung cancer (NSCLC). However, only a few safe and effective γ-secretase inhibitors have been discovered. Evodiamine (EVO), a compound derived from Euodiae Fructus (Chinese name, Wu-Zhu-Yu), exhibits remarkable anti-NSCLC activities. However, the underlying mechanisms of action have yet to be fully elucidated.

PURPOSE

We sought to determine the involvement of Notch3 signaling in the anti-NSCLC effects of EVO, and to explore whether EVO suppressed Notch3 signaling by inhibiting γ-secretase in cultured A549 and H1299 NSCLC cells and in urethane-induced lung cancer FVB mouse model.

METHODS

Cell viability, migration, stemness and cell cycle distribution of EVO were examined by the MTT assay, wound healing assay, soft agar colony assay and flow cytometry analysis, respectively. The binding affinity of EVO and γ-secretase complex was analyzed by molecular docking. Cellular thermal shift assay (CETSA) was performed to study the drug-target interactions in NSCLC cells. Protein levels were determined by Western blotting.

RESULTS

EVO dramatically inhibited cell viability, induced G2/M cell cycle arrest, suppressed cell migration, and reduced stemness in NSCLC cells. Mechanistic studies indicated that EVO prevented the γ-secretase cleavage of Notch3 at the cell surface and hence inhibited Notch3 activation. Moreover, EVO notably reduced tumor growth in the mouse model and inhibited Notch3 activity in the tumors.

CONCLUSION

This study provides new insights into the anti-NSCLC action of EVO, and suggests that suppressing Notch3 signaling by inhibiting γ-secretase is a mechanism of action underlying the anti-NSCLC effect of EVO.

Modulation of the Notch System in Response to Wnt Inhibition Induces Restoration of the Rat Luteal Function

The aim of this study was to investigate whether the Notch pathway is modulated in response to the downregulation of the Wnt/Β-catenin system in corpora lutea (CLs) from superovulated rats. To this end, we analyzed the effect of in vitro CL Wnt/Β-catenin inhibition on the expression of Notch members and on luteal function. Mechanically isolated rat CLs were cultured with ICG-001, a Wnt/B-catenin inhibitor. In this system, Wnt/B-catenin inhibition reduced progesterone production and decreased StAR protein levels. Besides, Wnt/B-catenin inhibition stimulated the Notch system, evidenced by an increase in Hes1 expression, and promoted the expression of selected Notch family members. At long incubation times, StAR levels and progesterone concentration reached the control values, effects probably mediated by the Notch pathway. These results provide the first evidence of a compensatory mechanism between Wnt/B-catenin signaling and the Notch system, which contributes to the homeostasis of luteal cells.

Convergence of Wnt and Notch signaling controls ovarian cancer cell survival

In the last 40 years ovarian cancer mortality rates have slightly declined and, consequently, it continues to be the fifth cause of cancer death in women. In the present study, we showed that β-catenin signaling is involved in the functions of ovarian cancer cells and interacts with the Notch system. Wnt and Notch systems showed to be prosurvival for ovarian cancer cells and their inhibition impaired cell proliferation and migration. We also demonstrated that the inhibition of β-catenin by means of two molecules, XAV939 and ICG-001, decreased the proliferation of the IGROV1 and SKOV3 ovarian cancer cell lines and that ICG-001 increased the percentage of IGROV1 cells undergoing apoptosis. The simultaneous inhibition of β-catenin and Notch signaling, by using the DAPT inhibitor, decreased ovarian cancer cell proliferation to the same extent as targeting only the Wnt/β-catenin pathway. A similar effect was observed in IGROV1 cell migration with ICG-001 and DAPT. ICG-001 increased the Notch target genes Hes-1 and Hey-1 and increased Jagged1 expression. However, no changes were observed in Dll4 or Notch 1 and 4 expressions. Our results suggest that Notch and β-catenin signaling co-operate in ovarian cancer to ensure the proliferation and migration of cells and that this could be achieved, at least partly, by the upregulation of Notch Jagged1 ligand in the absence of Wnt signaling. We showed that the Wnt pathway crosstalks with Notch in ovarian cancer cell functions, which may have implications in ovarian cancer therapeutics.

HOXA4, down-regulated in lung cancer, inhibits the growth, motility and invasion of lung cancer cells

The involvement of HOXA4 in colorectal cancer and epithelial ovarian cancer has been reported. Although it has been reported that the Hoxa4 gene is involved in the patterning of the mouse lung during embryonic development, little is known about the biological functions of HOXA4 in lung cancer. In the current study, HOXA4 expression was down-regulated in lung cancer tissues when compared with non-cancerous tissues. HOXA4 expression was associated with tumor size, TNM stage, lymph node metastasis and prognosis. Bioinformatics analysis revealed that HOXA4 expression was negatively correlated with cell cycle, metastasis, and the Wnt signaling pathway. Moreover, HOXA4 overexpression in lung cancer cell lines suppressed cell proliferation, migration, and invasion. HOXA4 decreased the protein expression levels of β-catenin, Cyclin D1, c-Myc and Survivin, indicating the inhibition of Wnt signaling. HOXA4 significantly increased the protein and mRNA levels of glycogen synthase kinase-3β (GSK3β) by promoting its transcription. Furthermore, inhibition of GSK3β by LiCl abolished the suppression of cell growth, migration, and invasion mediated by HOXA4. Overexpression of HOXA4 in xenograft tumors also decreased tumor growth and Wnt signaling. Collectively, these data suggest that HOXA4 is a potential diagnostic and prognostic marker in lung cancer, and its overexpression could inhibit lung cancer progression in part by promoting GSK3β transcription.

Evodiamine, a Novel NOTCH3 Methylation Stimulator, Significantly Suppresses Lung Carcinogenesis in Vitro and in Vivo

Lung cancer is a leading cause of cancer-related deaths worldwide. NOTCH3 signaling is mainly expressed in non-small cell lung carcinoma (NSCLC), and has been proposed as a therapeutic target of NSCLC. While, few agents for preventing or treating NSCLC via targeting NOTCH3 signaling are used in modern clinical practice. Evodiamine (EVO), an alkaloid derived from Euodiae Fructus, possesses low toxicity and has long been shown to exert anti-lung cancer activity. However, the underlying anti-lung cancer mechanisms of EVO are not yet fully understood. In this study, we explored the involvement of NOTCH3 signaling in the anti-lung cancer effects of EVO. Urethane-induced lung cancer mouse model and two NSCLC cell models, A549 and H1299, were used to evaluate the in vivo and in vitro anti-lung cancer action of EVO. A DNA methyltransferase inhibitor was employed to investigate the role of NOTCH3 signaling in the anti-lung cancer effects of EVO. Results showed that EVO potently reduced tumor size and tumor numbers in mice, and inhibited NOTCH3 in the tumors. EVO also dramatically reduced cell viability, induced G2/M cell cycle arrest, inhibited cell migration and reduced stemness in cultured NSCLC cells. Mechanistic studies showed that EVO potently inhibited NOTCH3 signaling by activation of DNMTs-induced NOTCH3 methylation. Importantly, inhibition of NOTCH3 methylation in NSCLC cells diminished EVO's anti-NSCLC effects. Collectively, EVO, a novel NOTCH3 methylation stimulator, exerted potent anti-lung cancer effects partially by inhibiting NOTCH3 signaling. These findings provide new insight into the EVO's anti-NSCLC action, and suggest a potential role of EVO in lung cancer prevention and treatment.

Cigarette smoke enhances initiation and progression of lung cancer by mutating Notch1/2 and dysregulating downstream signaling molecules

Lung cancer is the primary cause of cancer related deaths in the western world and smoking significantly increases the risk of developing lung cancer. Smoking enhances lung cancer initiation and progression. The effects of cigarette smoke on lung cancer are mediated by the presence of highly mutagenic substances, including nicotine, leading to mutations in oncogenes and tumor suppressor genes. An emerging pathway in cancer is the Notch signaling pathway which is essential for embryonic lung development and tissue homeostasis. The role of Notch signaling in lung cancer remains controversial and no studies have directly linked cigarette exposure to mutations in Notch. Therefore, we investigated the direct effect of Notch signaling pathways on cigarette-induced lung tumors and the correlation between smoking and mutations in Notch leading to altered downstream signaling. Human cell lines, mouse models and clinical lung cancer samples were utilized in this study. Cigarette-induced in vitro human lung cancer models and in vivo mouse models demonstrated strong effects of cigarette exposure on the Notch signaling pathway. Immunohistochemistry (IHC) of 50 clinical samples collected from smokers and non-smokers with and without lung cancer also demonstrated a link between smoking and changes in Notch signaling. Finally, 34 lung cancer samples analyzed through direct sequencing indicated smoking significantly increased small nucleotide polymorphisms (SNPs) in Notch 1 and 2 and specific SNPs significantly modulated expression levels of downstream signaling pathway molecules. Taken together, these results demonstrate a direct effect of smoking on the Notch signaling pathway leading to lung cancer initiation and progression.

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.

Synergistic Effect of Notch-3-Specific Inhibition and Paclitaxel in Non-Small Cell Lung Cancer (NSCLC) Cells Via Activation of The Intrinsic Apoptosis Pathway

BACKGROUND Lung cancers are resistant to conventional chemotherapeutic interventions such as paclitaxel. Notch signaling is crucial in the chemoresistance of lung cancer cells. The Notch inhibitor gamma-secretase inhibitor (GSI) inhibits the Notch signaling pathway. MATERIAL AND METHODS Here, we evaluated how Notch-3 inhibition by GSI can enhance the sensitivity of lung cancer cells to paclitaxel. To study how Notch-3-specific inhibition affects non-small cell lung cancer (NSCLC), we compared the cell viability, apoptosis, and colony formation of A549 and H1299 cells treated with Notch-3 siRNA and GSI. RESULTS The expression levels of Notch-3 or Notch intracellular domain 3 (NICD3) and apoptosis-related proteins were measured and compared between different groups. Notch-3 was significantly overexpressed in both cell lines, and Notch-3 expression was elevated after paclitaxel treatment, indicating activation of the Notch signaling pathway. Inhibition of the Notch signaling pathway by GSI and Notch-3 siRNA reduced cell proliferation and induced apoptosis in A549 and H1299 cells, thereby boosting sensitivity of the cell lines to paclitaxel. Concomitant treatment with paclitaxel and GSI or siRNA downregulated Bcl-2 expression and upregulated Bax expression levels. CONCLUSIONS These results indicate a synergistic effect of Notch-3-specific inhibition and paclitaxel through alteration of the intrinsic apoptosis pathway, which was involved in Notch-3-induced chemoresistance in NSCLC cells, and GSI inhibited Notch-3-induced chemoresistance in a concentration-dependent manner. This approach that combines Notch-3-specific inhibition and paclitaxel would be likely to apply in NSCLC.

Regulation of Monocarboxylic Acid Transporter 1 Trafficking by the Canonical Wnt/β-Catenin Pathway in Rat Brain Endothelial Cells Requires Cross-talk with Notch Signaling

The transport of monocarboxylate fuels such as lactate, pyruvate, and ketone bodies across brain endothelial cells is mediated by monocarboxylic acid transporter 1 (MCT1). Although the canonical Wnt/β-catenin pathway is required for rodent blood-brain barrier development and for the expression of associated nutrient transporters, the role of this pathway in the regulation of brain endothelial MCT1 is unknown. Here we report expression of nine members of the frizzled receptor family by the RBE4 rat brain endothelial cell line. Furthermore, activation of the canonical Wnt/β-catenin pathway in RBE4 cells via nuclear β-catenin signaling with LiCl does not alter brain endothelialMct1mRNA but increases the amount of MCT1 transporter protein. Plasma membrane biotinylation studies and confocal microscopic examination of mCherry-tagged MCT1 indicate that increased transporter results from reduced MCT1 trafficking from the plasma membrane via the endosomal/lysosomal pathway and is facilitated by decreased MCT1 ubiquitination following LiCl treatment. Inhibition of the Notch pathway by the γ-secretase inhibitorN-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycinet-butyl ester negated the up-regulation of MCT1 by LiCl, demonstrating a cross-talk between the canonical Wnt/β-catenin and Notch pathways. Our results are important because they show, for the first time, the regulation of MCT1 in cerebrovascular endothelial cells by the multifunctional canonical Wnt/β-catenin and Notch signaling pathways.

Evaluation of role of Notch3 signaling pathway in human lung cancer cells

There is still a debate on the extent to which Notch3 signaling is involved in lung carcinogenesis and whether such function is dependent on cancer type or not.

PURPOSE

To evaluate Notch3 expression in different types of human lung cancer cells.

METHODS

Notch3 was detected in human lung cancer cell lines and in tissues. Then, small interfering RNA (siRNA) was used to down-regulate the expression of Notch3 in H69AR small cell lung carcinoma (SCLC) cells; two non-small cell lung carcinoma (NSCLC) cells; A549 adenocarcinoma (ADC); and H2170 squamous cell carcinoma (SCC). In addition, Notch3 intracellular domain (N3ICD) plasmid was transfected into H1688 human SCLC cells. We observed the effect of deregulating Notch3 signaling on the following cell properties: Notch-related proteins, cell morphology, adhesion, epithelial-mesenchymal transition (EMT), motility, proliferation and neuroendocrine (NE) features of SCLC.

RESULTS

Notch3 is mainly expressed in NSCLC, and the expression of Notch1, Hes1 and Jagged1 is affected by Notch3. Notch3 has opposite functions in SCLC and NSCLC, being a tumor suppressor in the former and tumor promoting in the latter, in the context of cell adhesion, EMT and motility. Regarding cell proliferation, we found that inhibiting Notch3 in NSCLC decreases cell proliferation and induces apoptosis in NSCLC. Notch3 has no effect on cell proliferation or NE features of SCLC.

CONCLUSION

Notch3 signaling in lung carcinoma is dependent on cell type. In SCLC, Notch3 behaves as a tumor suppressor pathway, while in NSCLC it acts as a tumor-promoting pathway.

Epidermal growth factor receptor status and Notch inhibition in non-small cell lung cancer cells

BACKGROUND

Notch may behave as an oncogene or a tumor suppressor gene in lung cancer cells. Notch receptor undergoes cleavage by enzymes, including γ-secretase, generating the active Notch intracellular domain (NICD). The aim of the present study was to investigate the effect of DAPT, a γ-secretase inhibitor, in non-small cell lung cancer (NSCLC) cells, as well as the impact of epidermal growth factor (EGF) that is over-expressed by NSCLC cells, on Notch signaling. H23, A549, H661 and HCC827 human NSCLC cell lines were used, expressing various NICD and EGF receptor (EGFR) protein levels.

RESULTS

DAPT decreased the number of H661 cells in a concentration-dependent manner, while it had a small effect on H23 and A549 cells and no effect on HCC827 cells that carry mutated EGFR. Notch inhibition did not affect the stimulatory effect of EGF on cell proliferation, while EGF prevented DAPT-induced NICD decrease in H23 and H661 cells. The type of cell death induced by DAPT seems to depend on the cell type.

CONCLUSIONS

Our data indicate that inhibition of Notch cleavage may not affect cell number in the presence of EGFR mutations and that EGFR may affect Notch signalling suggesting that a dual inhibition of these pathways might be promising in NSCLC.

The Wnt and Notch signalling pathways in the developing cochlea: Formation of hair cells and induction of regenerative potential

The Wnt and Notch signalling pathways control proliferation, specification, and cell fate choices during embryonic development and in adult life. Hence, there is much interest in both signalling pathways in the context of stem cell biology and tissue regeneration. In the developing ear, the Wnt and Notch signalling pathways specify otic cells and refine the ventral boundary of the otic placode. Since both signalling pathways control events essential for the formation of sensory cells, such as proliferation and hair cell differentiation, these pathways could hold promise for the regeneration of hair cells in adult mammalian cochlea. Indeed, modulating either the Wnt or Notch pathways can trigger the regenerative potential of supporting cells. In the neonatal mouse cochlea, Notch-mediated regeneration of hair cells partially depends on Wnt signalling, which implies an interaction between the pathways. This review presents how the Wnt and Notch signalling pathways regulate the formation of sensory hair cells and how modulating their activity induces regenerative potential in the mammalian cochlea.

Inhibition of Notch3 prevents monocrotaline-induced pulmonary arterial hypertension

It has been shown that activation of Notch3 signaling is involved in the development of pulmonary arterial hypertension (PAH) by stimulating pulmonary arteries remodeling, while the molecular mechanisms underlying this are still largely unknown. The aims of this study are to address these issues. Monocrotaline dramatically increased right ventricle systolic pressure to 39.0 ± 2.6 mmHg and right ventricle hypertrophy index to 53.4 ± 5.3% (P < 0.05 versus control) in rats, these were accompanied with significantly increased proliferation and reduced apoptosis of pulmonary vascular cells as well as pulmonary arteries remodeling. Treatment of PAH model with specific Notch inhibitor DAPT significantly reduced right ventricle systolic pressure to 26.6 ± 1.3 mmHg and right ventricle hypertrophy index to 33.5 ± 2.6% (P < 0.05 versus PAH), suppressed proliferation and enhanced apoptosis of pulmonary vascular cells as well as inhibited pulmonary arteries remodeling. Our results further indicated that level of Notch3 protein and NICD3 were increased in MCT-induced model of PAH, this was accompanied with elevation of Skp2 and Hes1 protein level and reduction of P27Kip1. Administration of rats with DAPT-prevented MCT induced these changes. Our results suggest that Notch3 signaling activation stimulated pulmonary vascular cells proliferation by Skp2-and Hes1-mediated P27Kip1 reduction, and Notch3 might be a new target to treat PAH.

Activation of Notch3 promotes pulmonary arterial smooth muscle cells proliferation via Hes1/p27Kip1 signaling pathway

Activation of the Notch3 cascade is involved in the development of pulmonary arterial hypertension by stimulating the proliferation of vascular smooth muscle cells. However, the detailed molecular mechanisms underlying this effect are still unclear. The present study aims to address this issue. We demonstrated that over-expression of intracellular domain of the Notch3 receptor (NICD3) by adenovirus transfection dramatically induced proliferation of primary cultured pulmonary artery smooth muscle cells. This was accompanied with up-regulation of Hes1 protein and down-regulation of p27Kip1 protein. More importantly, we observed that prior silencing of Hes1 with siRNA blocked NICD3 over-expression-induced p27Kip1 reduction and cell proliferation. The present study suggests that Hes1 lies downstream of NICD3 and particularly mediates Notch3 signaling-induced proliferation of pulmonary arterial smooth muscle cells by down-regulation of p27Kip1 expression.

Notch1 promotes hepatitis B virus X protein-induced hepatocarcinogenesis via Wnt/β-catenin pathway

Hepatitis B virus X protein (HBx) is implicated in the pathogenesis of hepatocellular carcinoma (HCC) via a network of signaling pathways. Notch pathway is a major member of the network. Notch signaling may generate opposing effect in different steps of carcinogenesis, depending on the tumor cell type and the status of other signaling pathways, such as Wnt signaling pathway. Our previous studies have shown that activated Notch1 signaling is required for HBx to promote proliferation and survival of human hepatic cell line L02. However, the exact mechanisms remain vague. Here, we used L02/HBx cell lines as a cell model to study the relationship between Notch and Wnt/β-catenin pathways in promoting proliferation. We observed that activated Notch1 and Wnt/β-catenin signaling pathways and L02 cell malignant transformation were induced by HBx. Inhibition of the Notch1 pathway decreased the activation of Wnt/β-catenin pathway and cell proliferation, while inhibition of the Wnt/β-catenin pathway impaired cell proliferation, but did not significantly affect Notch1 signaling pathway in L02/HBx cells. Furthermore, inhibition of the Wnt/β-catenin pathway overcame the inhibition effect of knockdown Notch1 on proliferation and survival in L02/HBx cells. Additionally, the activity of Wnt/β-catenin signaling appears to be consistent with Fzd10 expression. Therefore, we demonstrate that Wnt signaling is downstream of the Notch pathway in regulating proliferation of L02/HBx cells, and which may be related to Fzd10 instead of Fzd7. These data suggest a new model of HBx-related HCC via cooperation between Wnt and Notch pathways.

Curcumin suppresses cell proliferation through inhibition of the Wnt/β-catenin signaling pathway in medulloblastoma

Recently, the survival rate of medulloblastoma patients has greatly improved; yet, patients undergoing current treatment regimes suffer from serious therapy-related side-effects. The aim of the present study was to investigate the anticancer effects of curcumin on medulloblastoma cells by testing its capacity to suppress proliferation and regulate the Wnt/β-catenin pathway. In the present study, cell proliferation was determined by MTT assay. Cell cycle was observed by flow cytometry. The changes in the Wnt/β-catenin pathway were analyzed by immunofluorescence, western blot analysis and RT-PCR. Curcumin treatment resulted in a dose- and time-dependent inhibition of proliferation in the medulloblastoma cell line. Curcumin treatment arrested the cell-cycle at the G2/M phase. Furthermore, curcumin treatment led to activation of GSK-3β, reduced expression of β-catenin and its downstream target cyclin D1. The attenuation of the Wnt/β‑catenin pathway was due to the loss of nuclear β-catenin. In conclusion, curcumin can inhibit cell growth by suppressing the Wnt/β-catenin signaling pathway, and it has the potential to be developed as a therapeutic agent for medulloblastoma.

The roles of Notch3 on the cell proliferation and apoptosis induced by CHIR99021 in NSCLC cell lines: a functional link between Wnt and Notch signaling pathways

Wnt and Notch signaling pathways both play essential roles and interact closely in development and carcinogenesis, but their interaction in non-small-cell lung cancer (NSCLC) is poorly unknown. Here we investigated the effects of CHIR99021, a Wnt signaling agonist, or Notch3-shRNA, or the combined application of CHIR99021 and Notch3-shRNA on cell proliferation and apoptosis, as well as the expressions of Notch3, its downstream genes, cyclinA and caspase-3. Our results showed that CHIR99021 up-regulated the expression of Notch3 protein and HES1 and HEYL mRNA. CHIR99021 promoted cell proliferation and the expression of cyclinA, which were inhibited by Notch3-shRNA in these three cell lines. Moreover, Notch3-shRNA significantly attenuated the positive effects of CHIR99021 on cell proliferation and cyclinA in H460 and H157. As for apoptosis, Notch3-shRNA induced cell apoptosis and increased the expression of caspase-3, whereas CHIR99021 showed the different effects in these three cell lines. The inhibitory effect of CHIR99021 on apoptosis was significantly weakened by Notch3-shRNA only in H460. Overall, although the effects of CHIR99021 and the combined application of CHIR99021 and Notch3-shRNA on the cell proliferation and apoptosis aren’t completely similar in the three cell lines, our findings still indicate that Notch3 signaling can be activated by canonical Wnt signaling and a functional link between Wnt and Notch signaling pathways exists in NSCLC, at least, which partially is associated with their regulations on the expressions of cyclinA and caspase-3.

Notch inhibitor: a promising carcinoma radiosensitizer

Radiotherapy is an important part of modern cancer management for many malignancies, and enhancing the radiosensitivity of tumor cells is critical for effective cancer therapies. The Notch signaling pathway plays a key role in regulation of numerous fundamental cellular processes. Further, there is accumulating evidence that dysregulated Notch activity is involved in the genesis of many human cancers. As such, Notch inhibitors are attractive therapeutic agents, although as for other anticancer agents, they exhibit significant and potential side effects. Thus, Notch inhibitors may be best used in combination with other agents or therapy. Herein, we describe evidence supporting the use of Notch inhibitors as novel and potent radiosensitizers in cancer therapy.

Notch pathway activity identifies cells with cancer stem cell-like properties and correlates with worse survival in lung adenocarcinoma

PURPOSE

The cancer stem cell theory postulates that tumors contain a subset of cells with stem cell properties of self-renewal, differentiation, and tumor initiation. The purpose of this study is to determine the role of Notch activity in identifying lung cancer stem cells.

EXPERIMENTAL DESIGN

We investigated the role of Notch activity in lung adenocarcinoma using a Notch GFP reporter construct and a γ-secretase inhibitor (GSI), which inhibits Notch pathway activity.

RESULTS

Transduction of lung cancer cells with Notch GFP reporter construct identified a subset of cells with high Notch activity (GFP-bright). GFP-bright cells had the ability to form more tumor spheres in serum-free media and were able to generate both GFP-bright and GFP-dim (lower Notch activity) cell populations. GFP-bright cells were resistant to chemotherapy and were tumorigenic in serial xenotransplantation assays. Tumor xenografts of mice treated with GSI had decreased expression of downstream effectors of Notch pathway and failed to regenerate tumors upon reimplantation in NOD/SCID mice. Using multivariate analysis, we detected a statistically significant correlation between poor clinical outcome and Notch activity (reflected in increased Notch ligand expression or decreased expression of the negative modulators), in a group of 443 patients with lung adenocarcinoma. This correlation was further confirmed in an independent group of 89 patients with adenocarcinoma in which Hes-1 overexpression correlated with poor overall survival.

CONCLUSIONS

Notch activity can identify lung cancer stem cell-like population and its inhibition may be an appropriate target for treating lung adenocarcinoma.

Computational analysis of expression of human embryonic stem cell-associated signatures in tumors

Background

The cancer stem cell model has been proposed based on the linkage between human embryonic stem cells and human cancer cells. However, the evidences supporting the cancer stem cell model remain to be collected. In this study, we extensively examined the expression of human embryonic stem cell-associated signatures including core genes, transcription factors, pathways and microRNAs in various cancers using the computational biology approach.

Results

We used the class comparison analysis and survival analysis algorithms to identify differentially expressed genes and their associated transcription factors, pathways and microRNAs among normal vs. tumor or good prognosis vs. poor prognosis phenotypes classes based on numerous human cancer gene expression data. We found that most of the human embryonic stem cell- associated signatures were frequently identified in the analysis, suggesting a strong linkage between human embryonic stem cells and cancer cells.

Conclusions

The present study revealed the close linkage between the human embryonic stem cell associated gene expression profiles and cancer-associated gene expression profiles, and therefore offered an indirect support for the cancer stem cell theory. However, many interest issues remain to be addressed further.

Norcantharidin impairs medulloblastoma growth by inhibition of Wnt/β-catenin signaling

Medulloblastoma is one of the leading causes of morbidity and mortality in pediatric cancer. Wnt-active tumors, an independent molecular subgroup in medulloblastoma, are characterized by a distinct pattern of genomic aberrations. We assessed the anticancer activity of cantharidin and norcantharidin against medulloblastoma, as cell lines in vitro and in athymic nude mice in vivo. Cantharidin and norcantharidin treatment impaired the growth of DAOY and UW228 medulloblastoma cells and promoted the loss of β-catenin activation and the β-catenin nuclearization linked to N-cadherin impairment in vitro. Intra-peritoneal administration of norcantharidin inhibited the growth of intra-cerebellum tumors in orthotopic xenograft nude mice. Analysis of the xenograft tissues revealed enhanced neuronal differentiation and reduced β-catenin expression. Our findings suggest that norcantharidin has potential therapeutic applications in the treatment of medulloblastoma as a result of its ability to cross the blood-brain barrier and its impairment of Wnt-β-catenin signaling.