Crosstalk between NF-kappaB/p65 and beta-catenin/TCF4/p300 signalling pathways through alterations in GSK-3beta expression during trans-differentiation of endometrial carcinoma cells

A Complex Interplay between Notch Effectors and β-Catenin Signaling in Morular Differentiation of Endometrial Carcinoma Cells

Notch signaling contributes to tissue development and homeostasis, but little is known about its role in morular differentiation of endometrial carcinoma (Em Ca) cells. The current study focused on crosstalk between Notch and β-catenin signaling in Em Ca with morules. Promoters of hairy and enhancer of split 1 (Hes1) and mastermind-like 2 (MAML2) were activated by Notch intracellular domain 1 but not β-catenin, and a positive feedback loop between Hes1 and MAML2 was observed. Immunoreactivities for nuclear β-catenin, Hes1, and MAML2, as well as the interaction between β-catenin and Hes1 or MAML2, were significantly higher in morular lesions compared with surrounding carcinoma in Em Ca. Inhibition of glycogen synthase kinase-3β (GSK-3β) increased expression of total nuclear and cytoplasmic GSK-3β and its phosphorylated forms, as well as Notch intracellular domain 1, Hes1, and active β-catenin. GSK-3β inhibition also decreased proliferation and migration, consistent with the response of cells stably overexpressing Hes1. Finally, the nuclear/cytoplasmic GSK-3β score was significantly higher in morules compared with surrounding carcinoma in Em Ca, and it was positively correlated with nuclear β-catenin, Hes1, and MAML2 scores. This complex interplay between Notch effectors and β-catenin signaling through GSK-3β inhibition contributes to the establishment and maintenance of β-catenin-mediated morular differentiation, which is, in turn, associated with reduced proliferation and inhibition of migration in Em Ca.

Patterns of NFkB activation resulting from damage, reactive microglia, cytokines, and growth factors in the mouse retina

Müller glia are a cellular source for neuronal regeneration in vertebrate retinas. However, the capacity for retinal regeneration varies widely across species. Understanding the mechanisms that regulate the reprogramming of Müller glia into progenitor cells is key to reversing the loss of vision that occurs with retinal diseases. In the mammalian retina, NFkB signaling promotes glial reactivity and represses the reprogramming of Müller glia into progenitor cells. Here we investigate different cytokines, growth factors, cell signaling pathways, and damage paradigms that influence NFkB-signaling in the mouse retina. We find that exogenous TNF and IL1β potently activate NFkB-signaling in Müller glia in undamaged retinas, and this activation is independent of microglia. By comparison, TLR1/2 agonist indirectly activates NFkB-signaling in Müller glia, and this activation depends on the presence of microglia as Tlr2 is predominantly expressed by microglia, but not other types of retinal cells. Exogenous FGF2 did not activate NFkB-signaling, whereas CNTF, Osteopontin, WNT4, or inhibition of GSK3β activated NFkB in Müller glia in the absence of neuronal damage. By comparison, dexamethasone, a glucocorticoid agonist, suppressed NFkB-signaling in Müller glia in damaged retinas, in addition to reducing numbers of dying cells and the accumulation of reactive microglia. Although NMDA-induced retinal damage activated NFkB in Müller glia, optic nerve crush had no effect on NFkB activation within the retina, whereas glial cells within the optic nerve were responsive. We conclude that the NFkB pathway is activated in retinal Müller glia in response to many different cell signaling pathways, and activation often depends on signals produced by reactive microglia.

Periostin promotes ovarian cancer metastasis by enhancing M2 macrophages and cancer-associated fibroblasts via integrin-mediated NF-κB and TGF-β2 signaling

BACKGROUND

Ovarian cancer has the highest mortality among gynecological cancers due to late diagnosis and lack of effective targeted therapy. Although the study of interplay between cancer cells with their microenvironment is emerging, how ovarian cancer triggers signaling that coordinates with immune cells to promote metastasis is still elusive.

METHODS

Microarray and bioinformatics analysis of low and highly invasive ovarian cancer cell lines were used to reveal periostin (POSTN), a matrix protein with multifunctions in cancer, with elevated expression in the highly invasive cells. Anchorage independent assay, Western blot, RNA interference, confocal analysis and neutralizing antibody treatment were performed to analyze the effects of POSTN on tumor promotion and to explore the underlying mechanism. Chemotaxis, flow cytometry and cytokine array analyses were undertaken to analyze the involvement of POSTN in cancer-associated fibroblast (CAF) and macrophage modulation. Correlations between POSTN expression levels and clinical characteristics were analyzed using the Oncomine, commercial ovarian cancer cDNA and China Medical University Hospital patient cohort. In vivo effect of POSTN on metastasis was studied using a mouse xenograft model.

RESULTS

Expression of POSTN was found to be elevated in highly invasive ovarian cancer cells. We observed that POSTN was co-localized with integrin β3 and integrin β5, which was important for POSTN-mediated activation of ERK and NF-κB. Ectopic expression of POSTN enhanced whereas knockdown of POSTN decreased cancer cell migration and invasion in vitro, as well as tumor growth and metastasis in vivo. POSTN enhanced integrin/ERK/NF-κB signaling through an autocrine effect on cancer cells to produce macrophage attracting and mobilizing cytokines including MIP-1β, MCP-1, TNFα and RANTES resulting in increased chemotaxis of THP-1 monocytes and their polarization to M2 macrophages in vitro. In agreement, tumors derived from POSTN-overexpressing SKOV3 harbored more tumor-associated macrophages than the control tumors. POSTN induced TGF-β2 expression from ovarian cancer cells to promote activation of adipose-derived stromal cells to become CAF-like cells expressing alpha smooth muscle actin and fibroblast activation protein alpha. Consistently, increased CAFs were observed in POSTN overexpressing SKOV3 cells-derived metastatic tumors. In clinical relevance, we found that expression of POSTN was positively correlated with advanced-stage diseases and poor overall survival of patients.

CONCLUSIONS

Our study revealed a POSTN-integrin-NF-κB-mediated signaling and its involvement in enhancing M2 macrophages and CAFs, which could potentially participate in promoting tumor growth. Our results suggest that POSTN could be a useful prognosis marker and potential therapeutic target.

TP53 positivity combined with high fibrinogen expression defines a subtype of oral squamous cell carcinoma with an unfavorable prognosis

The number of deaths due to oral squamous cell carcinoma (OSCC), a malignant tumor of the oral cavity, is on the increase. We examined fibrinogen (FIB) expression in patients with OSCC and developed novel immunoprofile classification methods that include FIB. The plasma FIB level in patients with OSCC was elevated compared with that in patients with non-tumor oral disease (non-T); using a cut-off point of 342 mg/dL, we found the area under the curve-receiver operating characteristic level for OSCC was 0.745. Similarly, FIB expression in OSCC tissues was significantly higher compared with that in non-T tissues. Hierarchical clustering based on the immunoprofile of several markers including FIB, p53, and p16 revealed four groups that could be used to categorize OSCC cases (referred to as immunoprofile subtypes [IPS], I-IV). Tumors in IPS-II, which were FIB+/p53+, were associated with a significantly worse overall survival (OS) when compared with the other subtypes. We conclude that our IPS classification system can facilitate prognostic evaluation in OSCC, and that quantification of FIB is an important component of the classification strategy for this disease.

Pathological features of pyloric gland adenoma of the gallbladder in comparison with gastric subtype of intracholecystic papillary neoplasm

BACKGROUND AND AIMS

Pyloric gland adenoma (PGA) of the gallbladder is a polypoid, preinvasive epithelial neoplasm composed of uniform back-to-back, pyloric glands in a tubular configuration. Intracholecystic papillary neoplasm (ICPN), another preinvasive grossly visible neoplasm of the gallbladder, is subdividable into four subtypes, including gastric subtype. In this study, PGA was reappraised referring to gastric subtype of ICPN (gICPN).

MATERIALS AND METHODS

PGA and gICPN pathologically defined by WHO 2019 classification were surveyed in a total of 104 cases of gallbladder epithelial neoplasms of our Hospital (2002 January to 2021 May) and were pathologically and immunohistochemically compared.

RESULTS

PGA (7 cases) was characterized by i) a well-demarcated, polypoid lesion and ii) packed tubular components resembling pyloric glands. gICPNs (14 cases) were subdivided into i) pyloric gland predominant (2 cases), ii) foveola predominant (6 cases) and iii) mixed foveola and pyloric gland type (6 cases). gICPNs were also divided into a solitary, polypoid lesion with well demarcation from the surrounding mucosa (5 cases) and a conglomerated polypoid and granular lesions with poor demarcation (9 cases). PGA shared gross and histologic features with solitary, polypoid gICPNs, and PGA could be regarded as solitary gICPN predominantly composed of pyloric glands. Nuclear expression of β-catenin was found in 6 of 7 PGA, but absent in gICPN, including solitary, polypoid gICPN.

CONCLUSION

PGA could correspond to a solitary gICPN mainly composed of pyloric glands, but may undergo a different molecular pathway from gICPN.

Targeting the crosstalk between canonical Wnt/β-catenin and inflammatory signaling cascades: A novel strategy for cancer prevention and therapy

Emerging scientific evidence indicates that inflammation is a critical component of tumor promotion and progression. Most cancers originate from sites of chronic irritation, infections and inflammation, underscoring that the tumor microenvironment is largely orchestrated by inflammatory cells and pro-inflammatory molecules. These inflammatory components are intimately involved in neoplastic processes which foster proliferation, survival, invasion, and migration, making inflammation the primary target for cancer prevention and treatment. The influence of inflammation and the immune system on the progression and development of cancer has recently gained immense interest. The Wnt/β-catenin signaling pathway, an evolutionarily conserved signaling strategy, has a critical role in regulating tissue development. It has been implicated as a major player in cancer development and progression with its regulatory role on inflammatory cascades. Many naturally-occurring and small synthetic molecules endowed with inherent anti-inflammatory properties inhibit this aberrant signaling pathway, making them a promising class of compounds in the fight against inflammatory cancers. This article analyzes available scientific evidence and suggests a crosslink between Wnt/β-catenin signaling and inflammatory pathways in inflammatory cancers, especially breast, gastrointestinal, endometrial, and ovarian cancer. We also highlight emerging experimental findings that numerous anti-inflammatory synthetic and natural compounds target the crosslink between Wnt/β-catenin pathway and inflammatory cascades to achieve cancer prevention and intervention. Current challenges, limitations, and future directions of research are also discussed.

Interplay of Opposing Effects of the WNT/β-Catenin Pathway and PPARγ and Implications for SARS-CoV2 Treatment

The Coronavirus disease 2019 (COVID-19), caused by the novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), has quickly reached pandemic proportions. Cytokine profiles observed in COVID-19 patients have revealed increased levels of IL-1β, IL-2, IL-6, and TNF-α and increased NF-κB pathway activity. Recent evidence has shown that the upregulation of the WNT/β-catenin pathway is associated with inflammation, resulting in a cytokine storm in ARDS (acute respire distress syndrome) and especially in COVID-19 patients. Several studies have shown that the WNT/β-catenin pathway interacts with PPARγ in an opposing interplay in numerous diseases. Furthermore, recent studies have highlighted the interesting role of PPARγ agonists as modulators of inflammatory and immunomodulatory drugs through the targeting of the cytokine storm in COVID-19 patients. SARS-CoV2 infection presents a decrease in the angiotensin-converting enzyme 2 (ACE2) associated with the upregulation of the WNT/β-catenin pathway. SARS-Cov2 may invade human organs besides the lungs through the expression of ACE2. Evidence has highlighted the fact that PPARγ agonists can increase ACE2 expression, suggesting a possible role for PPARγ agonists in the treatment of COVID-19. This review therefore focuses on the opposing interplay between the canonical WNT/β-catenin pathway and PPARγ in SARS-CoV2 infection and the potential beneficial role of PPARγ agonists in this context.

The Landscape of Glycogen Synthase Kinase-3 Beta Genomic Alterations in Cancer

Glycogen synthase kinase-3β (GSK-3β), a serine/threonine kinase, has been implicated in the pathogenesis of many cancers, with involvement in cell-cycle regulation, apoptosis, and immune response. Small-molecule GSK-3β inhibitors are currently undergoing clinical investigation. Tumor sequencing has revealed genomic alterations in GSK-3β, yet an assessment of the genomic landscape in malignancies is lacking. This study assessed >100,000 tumors from two databases to analyze GSK-3β alterations. GSK-3β expression and immune cell infiltrate data were analyzed across cancer types, and programmed death-ligand 1 (PD-L1) expression was compared between GSK-3β-mutated and wild-type tumors. GSK-3β was mutated at a rate of 1%. The majority of mutated residues were in the kinase domain, with frequent mutations occurring in a GSK-3β substrate binding pocket. Uterine endometrioid carcinoma was the most commonly mutated (4%) tumor, and copy-number variations were most commonly observed in squamous histologies. Significant differences across cancer types for GSK-3β-mutated tumors were observed for B cells (P = 0.018), monocytes (P = 0.002), dendritic cells (P = 0.005), neutrophils (P = 0.0003), and endothelial cells (P = 0.014). GSK-3β mRNA expression was highest in melanoma. The frequency of PD-L1 expression was higher among GSK-3β-mutated tumors compared with wild type in colorectal cancer (P = 0.03), endometrial cancer (P = 0.05), melanoma (P = 0.02), ovarian carcinoma (P = 0.0001), and uterine sarcoma (P = 0.002). Overall, GSK-3β molecular alterations were detected in approximately 1% of solid tumors, tumors with GSK-3β mutations displayed a microenvironment with increased infiltration of B cells, and GSK-3β mutations were associated with increased PD-L1 expression in selected histologies. These results advance the understanding of GSK-3β complex signaling network interfacing with key pathways involved in carcinogenesis and immune response.

S100A4/Nonmuscle Myosin IIA/p53 Axis Contributes to Aggressive Features in Ovarian High-Grade Serous Carcinoma

S100A4 is a small calcium-binding protein that exerts its biological functions by interacting with nonmuscle myosin IIA (NMIIA) and p53. Although S100A4 promotes metastasis in several tumors, little is known about its involvement in the progression of ovarian high-grade serous carcinomas (HGSCs). Herein, we focused on functional roles of the S100A4/NMIIA/p53 axis in these tumors. In HGSC cell lines harboring mutant p53, knockdown (KD) of S100A4 reduced the expression of several epithelial-mesenchymal transition/cancer stem cell markers and the ALDH1^high population, consistent with an inhibition of stemness features. S100A4-KD also increased apoptosis, decreased cell proliferation, and accelerated cell mobility. This was accompanied by increased Snail expression, which, in turn, was likely due to loss of p53 function. In contrast, specific inhibition of NMIIA by blebbistatin induced phenotypes that-with the exception of cell proliferation and mobility-were opposite to those observed in S100A4-KD cells. In clinical samples, cytoplasmic and/or nuclear interactions between S100A4, NMIIA, and mutant p53 were observed. In addition, high expression of S100A4, but not NMIIA or p53, was a significant and independent unfavorable prognostic factor in HGSC patients. These findings suggest that, via its interaction with NMIIA and p53, overexpressed S100A4 may induce epithelial-mesenchymal transition/cancer stem cell properties in HGSC and elicit several other tumor-associated phenotypes.

Upregulation of fibronectin following loss of p53 function is a poor prognostic factor in ovarian carcinoma with a unique immunophenotype

Background

We previously demonstrated that ovarian high grade serous carcinomas (OHGSeCa) and ovarian clear cell carcinomas (OCCCa) with an HNF-1β+/p53+/ARID1A+ immunophenotype were associated with the worst unfavorable prognosis. To clarify the molecular mechanisms underlying this finding, we focused on alterations in the p53 signaling pathway in these tumors.

Methods

Changes in cell phenotype and function following knockdown of wild-type p53 (p53-KD) were assessed using OCCCa cells expressing endogenous HNF-1β and ARID1A. The prognostic significance of molecules that were deregulated following p53-KD was also examined using 129 OCCCa/OHGSeCa cases.

Results

p53-KD cells had increased expression of Snail, phospho-Akt (pAkt), and pGSK3β, and decreased E-cadherin expression, leading to epithelial-mesenchymal transition (EMT)/cancer stem cell (CSC) features. The cells also exhibited acceleration of cell motility and inhibition of cell proliferation and apoptosis. Next generation sequencing revealed that fibronectin (FN) expression was significantly increased in the p53 KD-cells, in line with our observation that wild-type p53 (but not mutant p53) repressed FN1 promoter activity. In addition, treatment of OCCCa cells with FN significantly increased cell migration capacity and decreased cell proliferation rate, independent of induction of EMT features. In clinical samples, FN/p53 scores were significantly higher in OCCCa/OHGSeCa with the HNF-1β+/p53+/ARID1A+ immunophenotype when compared to others. Moreover, high FN/high p53 expression was associated with the worst overall survival and progression-free survival in OCCCa/OHGSeCa patients.

Conclusion

These findings suggest that upregulation of FN following loss of p53 function may impact the biological behavior of OCCCa/OHGSeCa, particularly in tumors with an HNF-1β+/p53+/ARID1A+ immunophenotype, through alterations in cell mobility and cell proliferation. The accompanying induction of EMT/CSC properties and inhibition of apoptosis due to p53 abnormalities also contribute to the establishment and maintenance of tumor phenotypic characteristics.

S100A4/non-muscle myosin II signaling regulates epithelial-mesenchymal transition and stemness in uterine carcinosarcoma

Uterine carcinosarcoma (UCS) represents a true example of cancer associated with epithelial-mesenchymal transition (EMT), which exhibits cancer stem cell (CSC)-like traits. Although S100A4 is an inducer of EMT, little is known about its involvement in UCS tumorigenesis. Herein, we focused on the functional role of S100A4 during development of UCS. Expression of S100A4 and molecules associated with its function were also examined in 35 UCS cases. In endometrial carcinoma cell lines, S100A4 promoter activity and mRNA levels were significantly increased by the transfection of NF-κB/p65, independent of a putative κB-binding site in the promoter. Cells stably overexpressing S100A4 showed enhancement of CSC properties, along with decreased cell proliferation and acceleration of cell migration. These phenotypes were abrogated in S100A4-knockdown cells. A combination of S100A4 antibody-mediated co-immunoprecipitation and shotgun proteomics analysis revealed that S100A4 strongly interacted with non-muscle myosin II (NMII) heavy chains, including myosin 9 and myosin 14. Specific inhibition of NMII by blebbistatin phenocopied S100A4 overexpression and induced a fibroblast-like morphology. In clinical samples, S100A4 score was significantly higher in sarcomatous as compared with carcinomatous components of UCS, and was positively correlated with ALDH1, Slug, and vimentin scores, and inversely with Ki-67 labeling indices. These findings suggest that an S100A4/NMII-related signaling cascade may contribute to the establishment and maintenance of EMT/CSC properties, along with changes in cell proliferation and migration capability. These events may be initiated in carcinomatous components in UCS and lead to divergent sarcomatous differentiation.

COX-2 mediated crosstalk between Wnt/β-catenin and the NF-κB signaling pathway during inflammatory responses induced by Haemophilus parasuis in PK-15 and NPTr cells

Haemophilus parasuis infection causes typical acute systemic inflammation in pigs, is characterized by fibrinous polyserositis inflammation, and results in great economic losses to the swine industry worldwide. However, the molecular details of how the host modulates the acute inflammatory response induced by H. parasuis are largely unknown. In previous studies, we found that H. parasuis high-virulence strain SH0165 infection induced the activation of both Wnt/β-catenin and NF-κB signaling in PK-15 and NPTr cells. In this study, we found that the activation of NF-κB, a central hub in inflammatory signaling, was impeded by the Wnt/β-catenin pathway during H. parasuis infection. In contrast, blocking NF-κB activity had no effect on the Wnt/β-catenin pathway during H. parasuis infection. Furthermore, we found that the inhibitory effect of β-catenin on NF-κB activity was mediated by its target gene, pig cyclooxygenase-2 (COX-2). Therefore, we demonstrated that H. parasuis infection activates the canonical Wnt/β-catenin signaling pathway, which leads to decreased NF-κB activity, reducing the acute inflammatory response in pigs. Additionally, the data provide a possible perspective for understanding the anti-inflammatory role of Wnt/β-catenin in pigs during bacterial infection.

Curcumin: a therapeutic strategy in cancers by inhibiting the canonical WNT/β-catenin pathway

Numerous studies have presented that curcumin could have a positive effect in the prevention of cancer and then in tumor therapy. Several hypotheses have highlighted that curcumin could decreases tumor growth and invasion by acting on both chronic inflammation and oxidative stress. This review focuses on the interest of use curcumin in cancer therapy by acting on the WNT/β-catenin pathway to repress chronic inflammation and oxidative stress. In the cancer process, one of the major signaling pathways involved is the WNT/β-catenin pathway, which appears to be upregulated. Curcumin administration participates to the downregulation of the WNT/β-catenin pathway and thus, through this action, in tumor growth control. Curcumin act as PPARγ agonists. The WNT/β-catenin pathway and PPARγ act in an opposed manner. Chronic inflammation, oxidative stress and circadian clock disruption are common and co-substantial pathological processes accompanying and promoting cancers. Circadian clock disruption related to the upregulation of the WNT/β-catenin pathway is involved in cancers. By stimulating PPARγ expression, curcumin can control circadian clocks through the regulation of many key circadian genes. The administration of curcumin in cancer treatment would thus appear to be an interesting therapeutic strategy, which acts through their role in regulating WNT/β-catenin pathway and PPARγ activity levels.

Targeting the Canonical WNT/β-Catenin Pathway in Cancer Treatment Using Non-Steroidal Anti-Inflammatory Drugs

Chronic inflammation and oxidative stress are common and co-substantial pathological processes accompanying and contributing to cancers. Numerous epidemiological studies have indicated that non-steroidal anti-inflammatory drugs (NSAIDs) could have a positive effect on both the prevention of cancer and tumor therapy. Numerous hypotheses have postulated that NSAIDs could slow tumor growth by acting on both chronic inflammation and oxidative stress. This review takes a closer look at these hypotheses. In the cancer process, one of the major signaling pathways involved is the WNT/β-catenin pathway, which appears to be upregulated. This pathway is closely associated with both chronic inflammation and oxidative stress in cancers. The administration of NSAIDs has been observed to help in the downregulation of the WNT/β-catenin pathway and thus in the control of tumor growth. NSAIDs act as PPARγ agonists. The WNT/β-catenin pathway and PPARγ act in opposing manners. PPARγ agonists can promote cell cycle arrest, cell differentiation, and apoptosis, and can reduce inflammation, oxidative stress, proliferation, invasion, and cell migration. In parallel, the dysregulation of circadian rhythms (CRs) contributes to cancer development through the upregulation of the canonical WNT/β-catenin pathway. By stimulating PPARγ expression, NSAIDs can control CRs through the regulation of many key circadian genes. The administration of NSAIDs in cancer treatment would thus appear to be an interesting therapeutic strategy, which acts through their role in regulating WNT/β-catenin pathway and PPARγ activity levels.

Inhibition of TPPP3 attenuates β-catenin/NF-κB/COX-2 signaling in endometrial stromal cells and impairs decidualization

Embryo implantation and decidualization are critical events that occur during early pregnancy. Decidualization is synchronized by the crosstalk of progesterone and the cAMP signaling pathway. Previously, we confirmed the role of TPPP3 during embryo implantation in mice, but the underlying role and mechanism of TPPP3 in decidualization has not yet been understood. The current study was aimed to investigate the role of TPPP3 in decidualization in vivo and in vitro. For in vivo experiments, decidual reaction was artificially induced in the uteri of BALB/c mice. TPPP3 was found to be highly expressed during decidualization, whereas in the uteri receiving TPPP3 siRNA, decidualization was suppressed and the expression of β-catenin and decidual marker prolactin was reduced. In human endometrium, TPPP3 protein was found to be predominantly expressed in the mid-secretory phase (LH+7). In the primary culture of human endometrial stromal cells (hESCs), TPPP3 siRNA knockdown inhibited stromal-to-decidual cell transition and decreased the expression of the decidualization markers prolactin and IGFBP-1. Immunofluorescence and immunoblotting experiments revealed that TPPP3 siRNA knockdown suppressed the expression of β-catenin, NF-κB and COX-2 in hESCs during decidualization. TPPP3 inhibition also decreased NF-kB nuclear accumulation in hESCs and suppressed NF-κB transcriptional promoter activity. COX-2 expression was significantly decreased in the presence of a selective NF-kB inhibitor (QNZ) implicating that NF-kB is involved in COX-2 expression in hESCs undergoing decidualization. TUNEL assay and FACS analysis revealed that TPPP3 knockdown induced apoptosis and caused loss of mitochondrial membrane potential in hESCs. The study suggested that TPPP3 plays a significant role in decidualization and its inhibition leads to the suppression of β-catenin/NF-κB/COX-2 signaling along with the induction of mitochondria-dependent apoptosis.

Interactions Between the Canonical WNT/Beta-Catenin Pathway and PPAR Gamma on Neuroinflammation, Demyelination, and Remyelination in Multiple Sclerosis

Multiple sclerosis (MS) is marked by neuroinflammation and demyelination with loss of oligodendrocytes in the central nervous system. The immune response is regulated by WNT/beta-catenin pathway in MS. Activated NF-kappaB, a major effector of neuroinflammation, and upregulated canonical WNT/beta-catenin pathway positively regulate each other. Demyelinating events present an upregulation of WNT/beta-catenin pathway, whereas proper myelinating phases show a downregulation of WNT/beta-catenin pathway essential for the promotion of oligodendrocytes precursors cells proliferation and differentiation. The activation of WNT/beta-catenin pathway results in differentiation failure and impairment in remyelination. However, PI3K/Akt pathway and TCF7L2, two downstream targets of WNT/beta-catenin pathway, are upregulated and promote proper remyelination. The interactions of these signaling pathways remain unclear. PPAR gamma activation can inhibit NF-kappaB, and can also downregulate the WNT/beta-catenin pathway. PPAR gamma and canonical WNT/beta-catenin pathway act in an opposite manner. PPAR gamma agonists appear as a promising treatment for the inhibition of demyelination and the promotion of proper remyelination through the control of both NF-kappaB activity and canonical WNT/beta-catenin pathway.

Crosstalk Between Peroxisome Proliferator-Activated Receptor Gamma and the Canonical WNT/β-Catenin Pathway in Chronic Inflammation and Oxidative Stress During Carcinogenesis

Inflammation and oxidative stress are common and co-substantial pathological processes accompanying, promoting, and even initiating numerous cancers. The canonical WNT/β-catenin pathway and peroxisome proliferator-activated receptor gamma (PPARγ) generally work in opposition. If one of them is upregulated, the other one is downregulated and vice versa. WNT/β-catenin signaling is upregulated in inflammatory processes and oxidative stress and in many cancers, although there are some exceptions for cancers. The opposite is observed with PPARγ, which is generally downregulated during inflammation and oxidative stress and in many cancers. This helps to explain in part the opposite and unidirectional profile of the canonical WNT/β-catenin signaling and PPARγ in these three frequent and morbid processes that potentiate each other and create a vicious circle. Many intracellular pathways commonly involved downstream will help maintain and amplify inflammation, oxidative stress, and cancer. Thus, many WNT/β-catenin target genes such as c-Myc, cyclin D1, and HIF-1α are involved in the development of cancers. Nuclear factor-kappaB (NFκB) can activate many inflammatory factors such as TNF-α, TGF-β, interleukin-6 (IL-6), IL-8, MMP, vascular endothelial growth factor, COX2, Bcl2, and inducible nitric oxide synthase. These factors are often associated with cancerous processes and may even promote them. Reactive oxygen species (ROS), generated by cellular alterations, stimulate the production of inflammatory factors such as NFκB, signal transducer and activator transcription, activator protein-1, and HIF-α. NFκB inhibits glycogen synthase kinase-3β (GSK-3β) and therefore activates the canonical WNT pathway. ROS activates the phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) signaling in many cancers. PI3K/Akt also inhibits GSK-3β. Many gene mutations of the canonical WNT/β-catenin pathway giving rise to cancers have been reported (CTNNB1, AXIN, APC). Conversely, a significant reduction in the expression of PPARγ has been observed in many cancers. Moreover, PPARγ agonists promote cell cycle arrest, cell differentiation, and apoptosis and reduce inflammation, angiogenesis, oxidative stress, cell proliferation, invasion, and cell migration. All these complex and opposing interactions between the canonical WNT/β-catenin pathway and PPARγ appear to be fairly common in inflammation, oxidative stress, and cancers.

Thermodynamic Aspects and Reprogramming Cellular Energy Metabolism during the Fibrosis Process

Fibrosis is characterized by fibroblast proliferation and fibroblast differentiation into myofibroblasts, which generate a relaxation-free contraction mechanism associated with excessive collagen synthesis in the extracellular matrix, which promotes irreversible tissue retraction evolving towards fibrosis. From a thermodynamic point of view, the mechanisms leading to fibrosis are irreversible processes that can occur through changing the entropy production rate. The thermodynamic behaviors of metabolic enzymes involved in fibrosis are modified by the dysregulation of both transforming growth factor β (TGF-β) signaling and the canonical WNT/β-catenin pathway, leading to aerobic glycolysis, called the Warburg effect. Molecular signaling pathways leading to fibrosis are considered dissipative structures that exchange energy or matter with their environment far from the thermodynamic equilibrium. The myofibroblastic cells arise from exergonic processes by switching the core metabolism from oxidative phosphorylation to glycolysis, which generates energy and reprograms cellular energy metabolism to induce the process of myofibroblast differentiation. Circadian rhythms are far-from-equilibrium thermodynamic processes. They directly participate in regulating the TGF-β and WNT/β-catenin pathways involved in energetic dysregulation and enabling fibrosis. The present review focusses on the thermodynamic implications of the reprogramming of cellular energy metabolism, leading to fibroblast differentiation into myofibroblasts through the positive interplay between TGF-β and WNT/β-catenin pathways underlying in fibrosis.

Interactions between TGF-β1, canonical WNT/β-catenin pathway and PPAR γ in radiation-induced fibrosis

Radiation therapy induces DNA damage and inflammation leading to fibrosis. Fibrosis can occur 4 to 12 months after radiation therapy. This process worsens with time and years. Radiation-induced fibrosis is characterized by fibroblasts proliferation, myofibroblast differentiation, and synthesis of collagen, proteoglycans and extracellular matrix. Myofibroblasts are non-muscle cells that can contract and relax. Myofibroblasts evolve towards irreversible retraction during fibrosis process. In this review, we discussed the interplays between transforming growth factor-β1 (TGF-β1), canonical WNT/β-catenin pathway and peroxisome proliferator-activated receptor gamma (PPAR γ) in regulating the molecular mechanisms underlying the radiation-induced fibrosis, and the potential role of PPAR γ agonists. Overexpression of TGF-β and canonical WNT/β-catenin pathway stimulate fibroblasts accumulation and myofibroblast differentiation whereas PPAR γ expression decreases due to the opposite interplay of canonical WNT/β-catenin pathway. Both TGF-β1 and canonical WNT/β-catenin pathway stimulate each other through the Smad pathway and non-Smad pathways such as phosphatidylinositol 3-kinase/serine/threonine kinase (PI3K/Akt) signaling. WNT/β-catenin pathway and PPAR γ interact in an opposite manner. PPAR γ agonists decrease β-catenin levels through activation of inhibitors of the WNT pathway such as Smad7, glycogen synthase kinase-3 (GSK-3 β) and dickkopf-related protein 1 (DKK1). PPAR γ agonists also stimulate phosphatase and tensin homolog (PTEN) expression, which decreases both TGF-β1 and PI3K/Akt pathways. PPAR γ agonists by activating Smad7 decrease Smads pathway and then TGF-β signaling leading to decrease radiation-induced fibrosis. TGF-β1 and canonical WNT/β-catenin pathway promote radiation-induced fibrosis whereas PPAR γ agonists can prevent radiation-induced fibrosis.

Cytosolic THUMPD1 promotes breast cancer cells invasion and metastasis via the AKT-GSK3-Snail pathway

Human THUMP domain-containing protein 1 (THUMPD1) is a specific adaptor protein that modulates tRNA acetylation through interaction with NAT10. Immunohistochemical analysis of 146 breast cancer specimens (82 triple-negative and 64 non-triple-negative cases) indicated THUMPD1 expression is higher in breast cancer tissues (60.9%, 89/146) than normal breast tissues (28.3%, 15/53; p < 0.001). Overall and cytosolic, but not nuclear, THUMPD1 expression in breast cancer correlated with advanced TNM stage (p = 0.003 and p < 0.001, respectively), lymph node metastasis (p = 0.001 and p < 0.001, respectively), and poor patient prognosis (p = 0.001 and p < 0.001, respectively). THUMPD1 interacted and co-localized with YAP, but did not affect Hippo pathway activity. THUMPD1 overexpression enhanced breast cancer cells invasion and migration in vivo and in vitro, possibly through activation of AKT, GSK3β and Snail, and inhibition of E-cadherin. Treatment with the AKT inhibitor, LY294002, reduced the effects of THUMPD1 overexpression in breast cancer cells. These results indicate that THUMPD1 promotes breast cancer cells invasion and migration via the AKT-GSK3β-Snail pathway.

Aerobic Glycolysis Hypothesis Through WNT/Beta-Catenin Pathway in Exudative Age-Related Macular Degeneration

Exudative age-related macular degeneration (AMD) is characterized by molecular mechanisms responsible for the initiation of choroidal neovascularization (CNV). Inflammatory processes are associated with upregulation of the canonical WNT/beta-catenin pathway in exudative AMD. We focus this review on the link between WNT/beta-catenin pathway activation and neovascular progression in exudative AMD through activation of aerobic glycolysis for production of angiogenic factors. Increased WNT/beta-catenin pathway involves hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2). WNT/beta-catenin pathway stimulates PI3K/Akt pathway and then HIF-1alpha which activates glycolytic enzymes: glucose transporter (Glut), pyruvate dehydrogenase kinase 1 (PDK1), lactate dehydrogenase A (LDH-A), and monocarboxylate lactate transporter (MCT-1). This phenomenon is called aerobic glycolysis or the Warburg effect. Consequently, phosphorylation of PDK-1 inhibits the pyruvate dehydrogenase complex (PDH). Thus, a large part of pyruvate cannot be converted into acetyl-CoA in mitochondria and only a part of acetyl-CoA can enter the tricarboxylic acid cycle. Cytosolic pyruvate is converted into lactate through the action of LDH-A. In exudative AMD, high level of cytosolic lactate is correlated with increase of VEGF expression, the angiogenic factor of CNV. Photoreceptors in retina cells can metabolize glucose through aerobic glycolysis to protect them against oxidative damage, as cancer cells do.

Functional role of ALK-related signal cascades on modulation of epithelial-mesenchymal transition and apoptosis in uterine carcinosarcoma

BACKGROUND

Anaplastic lymphoma kinase (ALK), which is a receptor tyrosine kinase, is essentially and transiently expressed in the developing nervous system. Recently, the deregulated expression of full-length ALK has been observed in some primary solid tumors, but little is known about its involvement in the tumorigenesis of uterine carcinosarcomas (UCSs). Here we examined the functional role of the ALK gene in UCSs.

METHODS

Regulation and function of the ALK gene were assessed using two endometrial carcinoma cell lines. Expression of ALK and its related molecules were also investigated using clinical samples of UCSs.

RESULTS

In cell lines, ALK promoter activity was significantly increased by transfection of Sox11 and N-myc, which are known to contribute to neuronal properties. Cells stably overexpressing full-length ALK showed an enhancement of EMT properties mediated by TGF-β1 and HGF, along with an increase in phosphorylated (p) Akt and nuclear p65. Overexpression of p65 also led to transactivation of Twist1 gene, known as an EMT inducer. Finally, treatment of the stable ALK-overexpressing cells with doxorubicin resulted in inhibition of apoptosis with progressive increase in the expression ratio of both pAkt and bcl2 relative to total Akt and bax, respectively. In clinical samples, strong cytoplasmic ALK immunoreactivity and mRNA signals without rearrangement or amplification of the ALK locus were frequently observed in UCSs, particularly in the sarcomatous components. Further, ALK IHC score was found to be positively correlated with Sox11, N-myc, Twist1, and bcl2 scores.

CONCLUSION

ALK-related signal cascades containing Akt, NF-κB, Twist1, and bcl2 may participate in initial signaling for divergent sarcomatous differentiation driven from carcinomatous components in UCSs through induction of the EMT process and inhibition of apoptotic features.

Crosstalk between Wnt/β-Catenin and NF-κB Signaling Pathway during Inflammation

Besides its important role in embryonic development and homeostatic self-renewal in adult tissues, Wnt/β-catenin signaling exerts both anti-inflammatory and proinflammatory functions. This is, at least partially, due to either repressing or enhancing the NF-κB pathway. Similarly, the NF-κB pathway either positively or negatively regulates Wnt/β-catenin signaling. Different components of the two pathways are involved in this crosstalk, forming a complex regulatory network. This review summarizes our current understanding of the molecular mechanisms underlying the cross-regulation between the two pathways and discusses their involvement in inflammation and inflammation-associated diseases such as cancer.

Cloning, identification and functional analysis of a β-catenin homologue from Pacific white shrimp, Litopenaeus vannamei

Wnt signaling is known to control multiple of cellular processes such as cell differentiation, communication, apoptosis and proliferation, and is also reported to play a role during microbial infection. β-catenin is a key regulator of the Wnt signaling cascade. In the present study, we cloned and identified a β-catenin homologue from Litopenaeus vannamei termed Lvβ-catenin. The full-length of Lvβ-catenin transcript was 2797 bp in length within a 2451 bp open reading frame (ORF) that encoded a protein of 816 amino acids. Lvβ-catenin protein was comprised of several characteristic domains such as an N-terminal region of GSK-β consensus phosphorylation site and Coed coil section, a central region of 12 continuous Armadillo/β-Catenin-like repeat (ARM) domains and a C-terminal region. Real-time PCR showed Lvβ-catenin expression was responsive to Vibrio parahaemolyticus and white spot syndrome virus (WSSV) infection. Dual-reporter analysis showed that over-expression of Lvβ-catenin could induce activation of the promoter activities of several antimicrobial peptides (AMPs) such as shrimp PEN4, suggesting that Lvβ-catenin could play a role in regulating the production of AMPs. Knockdown of Lvβ-catenin enhanced the sensitivity of shrimps to V. parahaemolyticus and WSSV challenge, suggesting Lvβ-catenin could play a positive role against bacterial and viral pathogens. In summary, the results presented in this study provided some insights into the function of Wnt/β-catenin of shrimp in regulating AMPs and the host defense against invading pathogens.

Distinct Effect of TCF4 on the NFκB Pathway in Human Primary Chondrocytes and the C20/A4 Chondrocyte Cell Line

OBJECTIVE

Previous studies indicated a difference in crosstalk between canonical WNT pathway and nuclear factor-κB (NFκB) signaling in human and animal chondrocytes. To assess whether the differences found were dependent on cell types used, we tested the effect of WNT modulation on NFκB signaling in human primary articular chondrocytes in comparison with the immortalized human costal chondrocyte cell line C20/A4.

DESIGN

We used gene expression analysis to study the effect of WNT modulation on IL1β-induced matrix metalloproteinase (MMP) expression as well as on WNT and NFκB target gene expression. In addition, we tested the involvement of RelA and TCF4 on activation of the WNT and NFκB pathway by TCF/LEF and NFκB reporter experiments, respectively.

RESULTS

We found an inhibitory effect of both induction and inhibition of WNT signaling on IL1β-induced MMP mRNA expression in primary chondrocytes, whereas WNT modulation did not affect MMP expression in C20/A4 cells. Furthermore, TCF/LEF and NFκB reporter activation and WNT and NFκB target gene expression were regulated differentially by TCF4 and RelA in a cell type-dependent manner. Additionally, we found significantly higher mRNA and protein expression of TCF4 and RelA in C20/A4 cells in comparison with primary chondrocytes.

CONCLUSIONS

We conclude that WNT modulation of NFκB is, at least in part, cell type dependent and that the observed differences are likely because of impaired sensitivity of the NFκB pathway in C20/A4 cells to modulations in WNT signaling. This might be caused by higher basal levels of TCF4 and RelA in C20/A4 cells compared to primary chondrocytes.

β-catenin promotes the type I IFN synthesis and the IFN-dependent signaling response but is suppressed by influenza A virus-induced RIG-I/NF-κB signaling

BACKGROUND

The replication cycle of most pathogens, including influenza viruses, is perfectly adapted to the metabolism and signal transduction pathways of host cells. After infection, influenza viruses activate several cellular signaling cascades that support their propagation but suppress those that interfere with viral replication. Accumulation of viral RNA plays thereby a central role. Its sensing by the pattern recognition receptors of the host cells leads to the activation of several signal transduction waves that result in induction of genes, responsible for the cellular innate immune response. Type I interferon (IFN) genes and interferon-stimulated genes (ISG) coding for antiviral-acting proteins, such as MxA, OAS-1 or PKR, are primary targets of these signaling cascades. β- and γ-catenin are closely related armadillo repeat-containing proteins with dual roles. At the cell membrane they serve as adapter molecules linking cell-cell contacts to microfilaments. In the cytosol and nucleus, the proteins form a transcriptional complex with the lymphoid enhancer factor/T-cell factor (LEF/TCF), regulating the transcription of many genes, thereby controlling different cellular functions such as cell cycle progression and differentiation.

RESULTS

In this study, we demonstrate that β- and γ-catenin are important regulators of the innate cellular immune response to influenza A virus (IAV) infections. They inhibit viral replication in lung epithelial cells by enhancing the virus-dependent induction of the IFNB1 gene and interferon-stimulated genes. Simultaneously, the prolonged infection counteracts the antiviral effect of β- and γ-catenin. Influenza viruses suppress β-catenin-dependent transcription by misusing the RIG-I/NF-κB signaling cascade that is induced in the course of infection by viral RNA.

CONCLUSION

We identified β- and γ-catenin as novel antiviral-acting proteins. While these factors support the induction of common target genes of the cellular innate immune response, their functional activity is suppressed by pathogen evasion.

IKK-β/NF-κB p65 mediates p27(Kip1) protein degradation in arsenite response

p27(Kip1) is a potent inhibitor of the cyclin-dependent kinases that drive G1 to S phase transition. Since deregulation of p27(Kip1) is found in many malignancies and is associated with the poor prognosis, elucidation of the molecular bases for regulation of p27(Kip1) expression is of great significance, not only in providing insight into the understanding of biological p27(Kip1), but also in the development of new cancer therapeutic tactics. We here explored the inhibitory regulation of IKKβ on p27(Kip1) expression following arsenite exposure. We found that although the basal level of p27(Kip1) expression in the IKKβ(-/-) cells is much lower than that in the IKKβ(+/+) cells, the deletion of IKKβ in the MEFs led to a marked increase in p27(Kip1) protein induction due to arsenite exposure in comparison to that in the IKKβ(+/+) cells. The IKKβ regulatory effect on p27(Kip1) expression was also verified in the IKKβ(-/-) and IKKβ(-/-) cells with IKKβ reconstitutional expression, IKKβ(-/-) (IKKβ). Further studies indicated that IKKβ-mediated p27(Kip1) downregulation occurred at protein degradation level via p65-dependent and p50-independent manner. Moreover, the results obtained from the comparison of arsenite-induced GSK3β activation among transfectants of WT, IKKβ(-/-) and IKKβ(-/-) (IKKβ), and the utilization of GSKβ shRNA, demonstrated that IKKβ regulation of p27 protein degradation was mediated by GSK3β following arsenite exposure.

Transcriptional upregulation of HIF-1α by NF-κB/p65 and its associations with β-catenin/p300 complexes in endometrial carcinoma cells

The hypoxia-inducible factor (HIF)-1α, which has a major role in cell adaptation to hypoxia, is mainly regulated at post-translational levels. Recently, HIF-1α mRNA was also shown to be upregulated by several signal pathways under normoxic conditions. Here we focused on relationships of HIF-1α with NF-κB and β-catenin signaling in endometrial carcinomas (Em Cas). Long-term exposure of Ishikawa cells to cobalt chloride (CoCl2), which is known to mimic the effect of hypoxia, caused a decrease in the growth, along with increased HIF-1α protein but not mRNA expression. In contrast, short-term exposure resulted in a rapid and transient increase in HIF-1α mRNA expression along with stabilization of nuclear NF-κB/p65 (p65). Transfection of p65 increased HIF-1α expression through activation of the promoter, whereas overexpression of HIF-1α also activated NF-κB-dependent transcription, indicating the existence of a positive feedback loop. In addition, HIF-1α was indirectly associated with nuclear β-catenin through interactions with p300, leading to slight enhancement of both HIF-1α- and β-catenin-mediated transcriptional activity. In clinical samples, biphasic upregulation of HIF-1α expression was observed in normal endometrial glandular components during the menstrual cycle, with the labeling indices showing significantly higher values in the early secretory stage. Significantly higher values for phosphorylated p65 and nuclear β-catenin were also observed in HIF-1α-positive than -negative lesions of Em Cas, in contrast to significantly lower Ki-67 status. These data therefore suggest that transcriptional associations with HIF-1α and NF-κB, as well as β-catenin/p300 complexes, may contribute to modulation of changes in tumor cell kinetics in response to a hypoxic condition in Em Cas.

4-1BB signaling activates the t cell factor 1 effector/β-catenin pathway with delayed kinetics via ERK signaling and delayed PI3K/AKT activation to promote the proliferation of CD8+ T Cells

4-1BB (CD137), an inducible costimulatory molecule, strongly enhances the proliferation and effector function of CD8(+) T cells. Since the serine/threonine kinase, glycogen synthase kinase-3 (GSK-3), is involved in a variety of signaling pathways of cellular proliferation, migration, immune responses, and apoptosis, we examined whether 4-1BB signaling activates GSK-3/β-catenin signaling and downstream transcription factors to enhance the proliferation of CD8(+) T cells. 4-1BB signaling induces rapid activation of ERK and IκB degradation, and shows delayed activation of AKT at 24 h post 4-1BB stimulation on anti-CD3 activated T cells. ERK and AKT signals were required for sustained β-catenin levels by inactivating GSK-3, which was also observed with delayed kinetics after 4-1BB stimulation. As a transcriptional partner of β-catenin, 4-1BB signaling decreased levels of FOXO1 and increased levels of stimulatory TCF1 in CD8(+) T cells at 2-3 days but not at early time points after 4-1BB engagement. The enhanced proliferation of CD8(+) T cells due to 4-1BB signaling was completely abolished by treatment with the TCF1/β-catenin inhibitor quercetin. These results show that 4-1BB signaling enhances the proliferation of activated CD8(+) T cells by activating the TCF1/β-catenin axis via the PI3K/AKT/ERK pathway. As effects of 4-1BB on AKT, FOXO1, β-catenin and GSK-3β showed delayed kinetics it is likely that an intervening molecule induced by 4-1BB and ERK signaling in activated T cells is responsible for these effects. These effects were observed on CD8(+) but not on CD4(+) T cells. Moreover, 4-1BB appeared to be unique among several TNFRs tested in inducing increase in stimulatory over inhibitory TCF-1.

Tumor necrosis factor α-induced hypoxia-inducible factor 1α-β-catenin axis regulates major histocompatibility complex class I gene activation through chromatin remodeling

Hypoxia-inducible factor 1α (HIF-1α) plays a crucial role in the progression of glioblastoma multiforme tumors, which are characterized by their effective immune escape mechanisms. As major histocompatibility complex class I (MHC-I) is involved in glioma immune evasion and since HIF-1α is a pivotal link between inflammation and glioma progression, the role of tumor necrosis factor alpha (TNF-α)-induced inflammation in MHC-I gene regulation was investigated. A TNF-α-induced increase in MHC-I expression and transcriptional activation was concurrent with increased HIF-1α, ΝF-κΒ, and β-catenin activities. While knockdown of HIF-1α and β-catenin abrogated TNF-α-induced MHC-I activation, NF-κB had no effect. β-Catenin inhibition abrogated HIF-1α activation and vice versa, and this HIF-1α-β-catenin axis positively regulated CREB phosphorylation. Increased CREB activation was accompanied by its increased association with β-catenin and CBP. Chromatin immunoprecipitation revealed increased CREB enrichment at CRE/site α on the MHC-I promoter in a β-catenin-dependent manner. β-Catenin replaced human Brahma (hBrm) with Brg1 as the binding partner for CREB at the CRE site. The hBrm-to-Brg1 switch is crucial for MHC-I regulation, as ATPase-deficient Brg1 abolished TNF-α-induced MHC-I expression. β-Catenin also increased the association of MHC-I enhanceosome components RFX5 and NF-YB at the SXY module. CREB acts as a platform for assembling coactivators and chromatin remodelers required for MHC-I activation in a HIF-1α/β-catenin-dependent manner.

Nuclear factor-κB modulates osteogenesis of periodontal ligament stem cells through competition with β-catenin signaling in inflammatory microenvironments

Inflammation can influence multipotency and self-renewal of mesenchymal stem cells (MSCs), resulting in their awakened bone-regeneration ability. Human periodontal ligament tissue-derived MSCs (PDLSCs) have been isolated, and their differentiation potential was found to be defective due to β-catenin signaling indirectly regulated by inflammatory microenvironments. Nuclear factor-κB (NF-κB) is well studied in inflammation by many different groups. The role of NF-κB needs to be studied in PDLSCs, although genetic evidences have recently shown that NF-κB inhibits osteoblastic bone formation in mice. However, the mechanism as to how inflammation leads to the modulation of β-catenin and NF-κB signaling remains unclear. In this study, we investigated β-catenin and NF-κB signaling through regulation of glycogen synthase kinase 3β activity (GSK-3β, which modulates β-catenin and NF-κB signaling) using a specific inhibitor LiCl and a phosphatidylinositol 3-kinase (PI3K) inhibitor LY 294002. We identified that NF-κB signaling might be more important for the regulation of osteogenesis in PDLSCs from periodontitis compared with β-catenin. BAY 11-7082 (an inhibitor of NF-κB) could inhibit phosphorylation of p65 and partly rescue the differentiation potential of PDLSCs in inflammation. Our data indicate that NF-κB has a central role in regulating osteogenic differentiation of PDLSCs in inflammatory microenvironments. Given the molecular mechanisms of NF-κB in osteogenic differentiation governed by inflammation, it can be said that NF-κB helps in improving stem cell-mediated inflammatory bone disease therapy.

Epithelial to mesenchymal transition in the pathogenesis of uterine malignant mixed Müllerian tumours: the role of ubiquitin proteasome system and therapeutic opportunities

Malignant mixed Müllerian tumours (malignant mixed mesodermal tumours, MMMT) of the uterus are metaplastic carcinomas with a sarcomatous component and thus they are also called carcinosarcomas. It has now been accepted that the sarcomatous component is derived from epithelial elements that have undergone metaplasia. The process that produces this metaplasia is epithelial to mesenchymal transition (EMT), which has recently been described as a neoplasia-associated programme shared with embryonic development and enabling neoplastic cells to move and metastasise. The ubiquitin proteasome system (UPS) regulates the turnover and functions of hundreds of cellular proteins. It plays important roles in EMT by being involved in the regulation of several pathways participating in the execution of this metastasis-associated programme. In this review the specifi c role of UPS in EMT of MMMT is discussed and therapeutic opportunities from UPS manipulations are proposed.

Transcriptional up-regulation of Sox9 by NF-κB in endometrial carcinoma cells, modulating cell proliferation through alteration in the p14(ARF)/p53/p21(WAF1) pathway

The Sox factors are a large family of transcription factors that play important roles in tumor development and progression in a variety of human malignancies and diverse developmental processes, but little is known about their roles in endometrial tumorigenesis. Herein, we focus on the functions of Sox9 in endometrial carcinomas. Cells stably overexpressing Sox9 showed a low proliferation rate, particularity in the exponential growth phase, along with increased amounts of p21(WAF1). Transient transfection of Sox9 caused transactivation of p21(WAF1) and p14(ARF) promoters, in cooperation with p53, resulting in activation of the p14(ARF)/p53/p21(WAF1) pathway. Overexpression of p65, and the constitutively active form myristylated Akt, led to an increase in Sox9 expression through transcriptional and posttranslational mechanisms. In normal endometrium, biphasic up-regulation of Sox9 expression was observed during the menstrual cycle, labeling indices being significantly higher in the proliferative stage than in the secretory stage. Moreover, expression also showed a significant stepwise increase from normal through grade 1 to grade 2/3 tumors, being correlated positively with labeling indices of p53, p21(WAF1), pp65, and Ki-67, probably due to a feedback system regarding cell proliferation through NF-κB and Akt signaling. These data, therefore, suggest that associations between Sox9 and NF-κB signaling, as well as Akt status, may participate in modulation of the cell kinetics of endometrial carcinomas cells through alteration in the p14(ARF)/p53/p21(WAF1) pathway.

Vimentin and PSF act in concert to regulate IbeA+ E. coli K1 induced activation and nuclear translocation of NF-κB in human brain endothelial cells

BACKGROUND

IbeA-induced NF-κB signaling through its primary receptor vimentin as well as its co-receptor PSF is required for meningitic E. coli K1 penetration and leukocyte transmigration across the blood-brain barrier (BBB), which are the hallmarks of bacterial meningitis. However, it is unknown how vimentin and PSF cooperatively contribute to IbeA-induced cytoplasmic activation and nuclear translocation of NF-κB, which are required for bacteria-mediated pathogenicities.

METHODOLOGY/PRINCIPAL FINDINGS

IbeA-induced E. coli K1 invasion, polymorphonuclear leukocyte (PMN) transmigration and IKK/NF-κB activation are blocked by Caffeic acid phenethyl ester (CAPE), an inhibitor of NF-κB. IKKα/β phosphorylation is blocked by ERK inhibitors. Co-immunoprecipitation analysis shows that vimentin forms a complex with IκB, NF-κB and tubulins in the resting cells. A dissociation of this complex and a simultaneous association of PSF with NF-κB could be induced by IbeA in a time-dependent manner. The head domain of vimentin is required for the complex formation. Two cytoskeletal components, vimentin filaments and microtubules, contribute to the regulation of NF-κB. SiRNA-mediated knockdown studies demonstrate that IKKα/β phosphorylation is completely abolished in HBMECs lacking vimentin and PSF. Phosphorylation of ERK and nuclear translocation of NF-κB are entirely dependent on PSF. These findings suggest that vimentin and PSF cooperatively contribute to IbeA-induced cytoplasmic activation and nuclear translocation of NF-κB activation. PSF is essential for translocation of NF-κB and ERK to the nucleus.

CONCLUSION/SIGNIFICANCE

These findings reveal previously unappreciated facets of the IbeA-binding proteins. Cooperative contributions of vimentin and PSF to IbeA-induced cytoplasmic activation and nuclear translocation of NF-κB may represent a new paradigm in pathogen-induced signal transduction and lead to the development of novel strategies for the prevention and treatment of bacterial meningitis.

Xrel3/XrelA attenuates β-catenin-mediated transcription during mesoderm formation in Xenopus embryos

In Xenopus laevis embryonic development, activation of the Wnt/β-catenin pathway promotes mesoderm cell fate determination via Xnr (Xenopus nodal-related) expression. We have demonstrated previously that Rel/NF-κB (nuclear factor κB) proteins expressed in presumptive ectoderm limit the activity of Xnrs to the marginal zone of embryos during mesoderm induction, which assists to distinguish mesoderm from ectoderm. The mechanism of this regulation, however, is unknown. In the present study, we investigated whether Rel/NF-κB proteins are able to modulate mesoderm formation by mediating Wnt/β-catenin signalling. We determined that ectopic expression of XrelA or Xrel3 in the dorsal marginal zone perturbed dorsal mesoderm formation by down-regulating multiple Wnt/β-catenin target genes including Xnr3, Xnr5 and Xnr6. Ventral co-expression of XrelA or Xrel3 with either wild-type β-catenin or constitutively active β-cateninS37A abrogated β-catenin-induced axis duplication and attenuated β-catenin-stimulated reporter transcription. Lastly, we provide evidence that Xrel3, but not XrelA, can interact with β-catenin without affecting the association of β-catenin with other transcriptional co-activators in vitro. Both Xrel3 and XrelA, however, prevented the accumulation, in nuclei, of exogenously expressed and endogenous β-catenin in vivo. These results suggest that Rel proteins are able to bind β-catenin and attenuate β-catenin-mediated transcription by nuclear exclusion.

Single nucleotide polymorphisms of TCF7L2 are linked to diabetic coronary atherosclerosis

Background

Coronary artery disease (CAD) shares common risk factors with type 2 diabetes (T2DM). Variations in the transcription factor 7-like 2 (TCF7L2) gene, particularly rs7903146, increase T2DM risk. Potential links between genetic variants of the TCF7L2 locus and coronary atherosclerosis are uncertain. We therefore investigated the association between TCF7L2 polymorphisms and angiographically determined CAD in diabetic and non-diabetic patients.

Methodology/Principal Findings

We genotyped TCF7L2 variants rs7903146, rs12255372, and rs11196205 in a cross-sectional study including 1,650 consecutive patients undergoing coronary angiography for the evaluation of established or suspected stable CAD. Significant CAD was diagnosed in the presence of coronary stenoses ≥50%. Variant rs7903146 in the total study cohort was significantly associated with significant CAD (adjusted additive OR = 1.29 [1.09–1.53]; p = 0.003). This association was strong and significant in T2DM patients (n = 393; OR = 1.91 [1.32–2.75]; p = 0.001) but not in non-diabetic subjects (OR = 1.09 [0.90–1.33]; p = 0.370). The interaction risk allele by T2DM was significant (p_interaction = 0.002), indicating a significantly stronger impact of the polymorphism on CAD in T2DM patients than in non-diabetic subjects. TCF7L2 polymorphisms rs12255372 and rs11196205 were also significantly associated with CAD in diabetic patients (adjusted additive OR = 1.90 [1.31–2.74]; p = 0.001 and OR = 1.75 [1.22–2.50]; p = 0.002, respectively). Further, haplotype analysis demonstrated that haplotypes including the rare alleles of all investigated variants were significantly associated with CAD in the whole cohort as well as in diabetic subjects (OR = 1.22 [1.04–1.43]; p = 0.013 and OR = 1.67 [1.19–2.22]; p = 0.003, respectively).

Conclusions/Significance

These results suggest that TCF7L2 variants rs7903146 rs12255372, and rs11196205 are significantly associated with angiographically diagnosed CAD, specifically in patients with T2DM. TCF7L2 therefore appears as a genetic link between diabetes and atherosclerosis.

Lentivirus-mediated gene silencing of beta-catenin inhibits growth of human tongue cancer cells

BACKGROUND

Beta-catenin is one of the key components of Wnt signaling pathway. Increased level of this protein has been proved to be associated with enhanced cellular proliferation and the development of many kinds of cancers. But its role in the carcinogenesis in human tongue squamous cell carcinoma, one of the most common carcinomas of the human oral cavity, remains poorly characterized.

METHODS

In this study, we used lentivirus-mediated RNA interference (RNAi) targeted against beta-catenin to determine the effects of decreasing the high constitutive level of this protein in human tongue carcinoma cell line Tca8113.

RESULTS

Our studies demonstrated that RNAi directly against beta-catenin markedly decreased beta-catenin gene expression and inhibited cellular proliferation as reflected in the reduced growth of tongue cancer cells both in vitro and in nude mice.

CONCLUSIONS

RNA interference (RNAi) targeting against beta-catenin can induce cell growth suppression of tongue cancer and may have the potential as a therapeutic modality to treat human tongue cancer.

Pin1 acts as a modulator of cell proliferation through alteration in NF-κB but not β-catenin/TCF4 signalling in a subset of endometrial carcinoma cells

Prolyl isomerase Pin1 is frequently up-regulated in a variety of human malignancies, modulating signalling in several oncogenic pathways, including those involving NF-κB and β-catenin. Our previous study provided evidence that alterations in these signal pathways are essential events during trans-differentiation of endometrial carcinoma (Em Ca) cells. Here we focused on the functional roles of Pin1. In normal endometrium, Pin1 expression showed a stepwise decrease from proliferative to secretory phases during the menstrual cycle, correlating positively with cell proliferation and expression of several cell cycle-related molecules including E2F1 and pRb. Transfection of E2F1 caused transactivation of Pin1, indicating control by E2F1/Rb pathways. In Em Cas with morules, Pin1 expression was found to be significantly increased in glandular but not in morular components, correlating inversely with nuclear accumulation of β-catenin. Overexpression also caused an increase in the stability of nuclear p65, leading to enhancement of NF-κB-mediated transactivation of the cyclin D1 gene, in contrast to minimal inhibition of β-catenin/TCF4 transcription activity. These findings indicate that Pin1 may play an important role in preserving cell proliferative activity in glandular carcinoma components through enhancement of NF-κB signalling, but its down-regulation may be a key signal for induction of trans-differentiation of Em Ca cells, contributing to a shift from NF-κB to β-catenin/TCF signalling pathways.

Mathematical modelling of Wnt/β-catenin signalling

The Wnt/β-catenin pathway plays an important role in development and disease. Theoretical approaches have been used to describe this pathway and have provided intriguing insights into its signalling characteristics. In the present paper, we review mathematical models of the pathway. We focus on a quantitative kinetic model for canonical Wnt/β-catenin signalling describing the reactions of the pathway's core compounds [Lee, Salic, Krüger, Heinrich and Kirschner (2003) PLoS Biol. 1, 116–132]. Numerous modifications and further analyses with respect to signalling characteristics, transcriptional feedback and cross-talk were performed. In addition, the role of β-catenin in gene expression and cell–cell adhesion as well as spatial aspects of signalling are investigated in various theoretical models.

Constitutive activation of glycogen synthase kinase-3beta correlates with better prognosis and cyclin-dependent kinase inhibitors in human gastric cancer

Background

Aberrant regulation of glycogen synthase kinase-3β (GSK-3β) has been implicated in several human cancers; however, it has not been reported in the gastric cancer tissues to date. The present study was performed to determine the expression status of active form of GSK-3β phosphorylated at Tyr²¹⁶ (pGSK-3β) and its relationship with other tumor-associated proteins in human gastric cancers.

Methods

Immunohistochemistry was performed on tissue array slides containing 281 human gastric carcinoma specimens. In addition, gastric cancer cells were cultured and treated with a GSK-3β inhibitor lithium chloride (LiCl) for immunoblot analysis.

Results

We found that pGSK-3β was expressed in 129 (46%) of 281 cases examined, and was higher in the early-stages of pathologic tumor-node-metastasis (P < 0.001). The expression of pGSK-3β inversely correlated with lymphatic invasion (P < 0.001) and lymph node metastasis (P < 0.001) and correlated with a longer patient survival (P < 0.001). In addition, pGSK-3β expression positively correlated with that of p16, p21, p27, p53, APC, PTEN, MGMT, SMAD4, or KAI1 (P < 0.05), but not with that of cyclin D1. This was confirmed by immunoblot analysis using SNU-668 gastric cancer cells treated with LiCl.

Conclusions

GSK-3β activation was frequently observed in early-stage gastric carcinoma and was significantly correlated with better prognosis. Thus, these findings suggest that GSK-3β activation is a useful prognostic marker for the early-stage gastric cancer.

Cross-Regulation Between Wnt and NF-κB Signaling Pathways

Cross-regulation between the Wnt and nuclear factor (NF)-κB signaling pathways has emerged as an important area for the regulation of a diverse array of genes and pathways active in chronic inflammation, immunity, development, and tumorigenesis. The ligands, kinases, transcription factors, and products of their target gene expression are involved in cross-regulation of these two signaling pathways. Both β-catenin and NF-κB activate inducible nitric oxide synthase (iNOS) gene expression; however, β-catenin also exerts an inhibitory effect on NF-κB-mediated transcriptional activation, including iNOS. The recent discovery of functional cross-regulation between these two pathways has shown complex roles for Wnt/β-catenin and NF-κB signaling in the pathogenesis of certain cancers and other diseases. This review focuses on the molecular mechanisms of cross-regulation between Wnt/β-catenin and NF-κB signaling pathways in cancer cells.

Progesterone inhibition of Wnt/beta-catenin signaling in normal endometrium and endometrial cancer

PURPOSE

Wnt signaling regulates the fine balance between stemness and differentiation. Here, the role of Wnt signaling to maintain the balance between estrogen-induced proliferation and progesterone-induced differentiation during the menstrual cycle, as well as during the induction of hyperplasia and carcinogenesis of the endometrium, was investigated.

EXPERIMENTAL DESIGN

Endometrial gene expression profiles from estradiol (E(2)) and E(2) + medroxyprogesterone acetate-treated postmenopausal patients were combined with profiles obtained during the menstrual cycle (PubMed; GEO DataSets). Ishikawa cells were transfected with progesterone receptors and Wnt inhibitors dickkopf homologue 1 (DKK1) and forkhead box O1 (FOXO1), measuring Wnt activation. Expression of DKK1 and FOXO1 was inhibited by use of sequence-specific short hairpins. Furthermore, patient samples (hormone-treated endometria, hyperplasia, and endometrial cancer) were stained for Wnt activation using nuclear beta-catenin and CD44.

RESULTS

In vivo, targets and components of the Wnt signaling pathway (among them DKK1 and FOXO1) are regulated by E(2) and progesterone. In Wnt-activated Ishikawa cells, progesterone inhibits Wnt signaling by induction of DKK1 and FOXO1. Furthermore, using siRNA-mediated knockdown of both DKK1 and FOXO1, progesterone inhibition of Wnt signaling was partly circumvented. Subsequently, immunohistochemical analysis of the Wnt target gene CD44 showed that progesterone acted as an inhibitor of Wnt signaling in hyperplasia and in well-differentiated endometrial cancer.

CONCLUSION

Progesterone induction of DKK1 and FOXO1 results in inhibition of Wnt signaling in the human endometrium. This Wnt inhibitory effect of progesterone is likely to play a rate-limiting role in the maintenance of endometrial homeostasis and, on its loss, in tumor onset and progression toward malignancy.

Requirement of the Akt/beta-catenin pathway for uterine carcinosarcoma genesis, modulating E-cadherin expression through the transactivation of slug

Uterine carcinosarcomas (UCSs) are considered to represent true examples of the epithelial-mesenchymal transition. Akt plays a key role in the induction of epithelial-mesenchymal transition, but little is known about its involvement in tumorigenesis. Here we examined the functional roles of the Akt/beta-catenin pathway in UCSs. In clinical samples, phospho-Akt (pAkt) expression was found to be significantly increased in mesenchymal compared with epithelial components, exhibiting both positive and negative correlations with nuclear beta-catenin and E-cadherin, respectively. Expression levels of the transcription factor Slug were also significantly up-regulated in the mesenchymal components and strongly correlated with both pAkt and nuclear beta-catenin. In endometrial cancer cell lines, active Akt induced the stabilization of nuclear beta-catenin through the phosphorylation of GSK-3beta, and this, in turn, led to the transactivation of Slug, which was mediated by nuclear beta-catenin. Moreover, Slug overexpression itself caused repression of E-cadherin, with subtle changes in cell morphology. In addition, knockdown of the retinoblastoma gene product (Rb) up-regulated pAkt and repressed E-cadherin, consistent with the in vivo finding of significantly decreased Rb expression in mesenchymal components. These findings suggest that changes in the Akt/beta-catenin pathway, as well as alterations in Rb expression, may be essential for both the establishment and maintenance of phenotypic characteristics of UCSs, playing key roles in the regulation of E-cadherin through the transactivation of the Slug gene.

Transcription factor Egr1 acts as an upstream regulator of beta-catenin signalling through up-regulation of TCF4 and p300 expression during trans-differentiation of endometrial carcinoma cells

The beta-catenin/TCF4/p300 pathway is involved in early signalling for trans-differentiation towards the morular phenotype of endometrial carcinoma cells, but little is known about the upstream regulators. Here we show that transcription factor early growth response 1 (Egr1) acts as an initial mediator through up-regulating the expression of TCF4 and p300. In an endometrial carcinoma cell line with abundant oestrogen receptor alpha, Egr1 expression at both mRNA and protein levels was significantly increased by serum and 17beta-oestradiol stimuli. Serum-stimulated cells also showed increased expression of TCF4 and p300, while inhibition of Egr1 by specific siRNAs resulted in decreased expression. Transfection of Egr1 led to transactivation of TCF4 as well as p300 genes, through specific binding to a promoter region, and thus in turn resulted in nuclear accumulation of beta-catenin mediated by the up-regulating TCF4. The overexpression also caused inhibition of beta-catenin/TCF4/p300-mediated transcription, probably through sequestration of p300. Egr1 promoter activity was increased by serum but not 17beta-oestradiol, in contrast to the marked repression associated with TCF4, p300, and Egr1 itself, indicating that the regulation involves several feedback loops. In clinical samples, cells immunopositive for nuclear Egr1, as well as beta-catenin and TCF4, were found to be sporadically distributed in glandular components of endometrial carcinoma with morules. A significant positive correlation between nuclear beta-catenin and TCF4 was observed, but no such link was evident for Egr1, probably due to the existence of negative feedback regulation. Together, these data indicate that Egr1 may participate in modulation of the beta-catenin/TCF4/p300 signalling pathway as an initial event during trans-differentiation of endometrial carcinoma cells, through its impact on several signalling networks.

Activation of epidermal growth factor receptor results in snail protein but not mRNA overexpression in endometrial cancer

Reduced E-cadherin expression is associated with tumour progression of many carcinomas, including endometrial cancers. The transcription factor Snail is known as one of the most prominent transcriptional E-cadherin repressors; its regulation in cancer tissues, however, still remains unclear. Here, we report that activation of epidermal growth factor receptor (EGFR) resulted in overexpression of Snail and also identified critical downstream signalling molecules. Stimulation of two endometrial carcinoma cell lines with epidermal growth factor (EGF) lead to an increase of Snail protein expression. In primary human endometrioid endometrial carcinomas Snail protein expression correlated with the activated, phosphorylated form of EGFR (Tyr1086) as revealed by profiling 24 different signalling proteins using protein lysate microarrays. In addition, we observed an inverse correlation between Snail and E-cadherin protein levels in these tumours. Most likely, p38 MAPK, PAK1, AKT, ERK1/2 and GSK-3β are involved in the up-regulation of Snail downstream of EGFR. Snail mRNA expression did not show a correlation with activated EGFR in these tumours. Taken together, profiling of signalling proteins in primary human tissues provided strong evidence that EGFR signalling is involved in Snail protein overexpression.