Fibroblast growth factor receptor-mediated activation of AKT-β-catenin-CBP pathway regulates survival and proliferation of murine hepatoblasts and hepatic tumor initiating stem cells

Modulating tumoral exosomes and fibroblast phenotype using nanoliposomes augments cancer immunotherapy

Cancer cells program fibroblasts into cancer associated fibroblasts (CAFs) in a two-step manner. First, cancer cells secrete exosomes to program quiescent fibroblasts into activated CAFs. Second, cancer cells maintain the CAF phenotype via activation of signal transduction pathways. We rationalized that inhibiting this two-step process can normalize CAFs into quiescent fibroblasts and augment the efficacy of immunotherapy. We show that cancer cell-targeted nanoliposomes that inhibit sequential steps of exosome biogenesis and release from lung cancer cells block the differentiation of lung fibroblasts into CAFs. In parallel, we demonstrate that CAF-targeted nanoliposomes that block two distinct nodes in fibroblast growth factor receptor (FGFR)-Wnt/β-catenin signaling pathway can reverse activate CAFs into quiescent fibroblasts. Co-administration of both nanoliposomes significantly improves the infiltration of cytotoxic T cells and enhances the antitumor efficacy of αPD-L1 in immunocompetent lung cancer-bearing mice. Simultaneously blocking the tumoral exosome-mediated activation of fibroblasts and FGFR-Wnt/β-catenin signaling constitutes a promising approach to augment immunotherapy.

Genetic heterogeneity of liver cancer stem cells

Cancer cell heterogeneity is a serious problem in the control of tumor progression because it can cause chemoresistance and metastasis. Heterogeneity can be generated by various mechanisms, including genetic evolution of cancer cells, cancer stem cells (CSCs), and niche heterogeneity. Because the genetic heterogeneity of CSCs has been poorly characterized, the genetic mutation status of CSCs was examined using Exome-Seq and RNA-Seq data of liver cancer. Here we show that different surface markers for liver cancer stem cells (LCSCs) showed a unique propensity for genetic mutations. Cluster of differentiation 133 (CD133)-positive cells showed frequent mutations in the IRF2, BAP1, and ERBB3 genes. However, leucine-rich repeat-containing G protein-coupled receptor 5-positive cells showed frequent mutations in the CTNNB1, RELN, and ROBO1 genes. In addition, some genetic mutations were frequently observed irrespective of the surface markers for LCSCs. BAP1 mutations was frequently observed in CD133-, CD24-, CD13-, CD90-, epithelial cell adhesion molecule-, or keratin 19-positive LCSCs. ASXL2, ERBB3, IRF2, TLX3, CPS1, and NFATC2 mutations were observed in more than three types of LCSCs, suggesting that common mechanisms for the development of these LCSCs. The present study provides genetic heterogeneity depending on the surface markers for LCSCs. The genetic heterogeneity of LCSCs should be considered in the development of LCSC-targeting therapeutics.

TWEAK/FN14 promotes profibrogenic pathway activation in Prominin-1-expressing hepatic progenitor cells in biliary atresia

BACKGROUND AND AIMS

Biliary atresia (BA), a congenital cholestatic liver disease, commonly culminates in end-stage liver disease. We previously demonstrated in BA that Prominin-1 ( Prom1 )-expressing hepatic progenitor cells (HPCs) expand within regions of developing fibrosis, giving rise to cholangiocytes within biliary ductular reactions. Null mutation of Prom1 or ablation of cells expressing Prom1 significantly diminishes fibrogenesis. FN14, the receptor for TNF-like weak inducer of apoptosis (TWEAK), is expressed by HPCs. TWEAK/FN14 signaling promotes fibrosis in multiple organ systems. Therefore, we hypothesized that TWEAK/FN14 signaling mediates Prom1 -expressing HPC proliferation leading to profibrogenic ductular reactions in BA.

APPROACH AND RESULTS

The experimental mouse model of BA mediated by perinatal rhesus rotavirus (RRV) infection resulted in increased co-expression of Fn14 in Prom1 -expressing HPCs within regions of ductular reactions. FN14 antagonist L524-0366 decreased ductular reactions, biliary fibrosis and periportal fibroblast activation in RRV injury. L524-0366 inhibition also demonstrated loss of downstream noncanonical NF-kB signaling expression in RRV injury. Murine HPC organoids demonstrated accelerated organoid growth and proliferation when treated with recombinant TWEAK. Increased organoid proliferation with recombinant TWEAK was lost when also treated with L524-0366. Analysis of a large publicly available RNA sequencing database of BA and normal control patients revealed significant increases in expression of PROM1 , FN14 , and genes downstream of TNF signaling and noncanonical NF-κB signaling pathways in BA infants. Infants who failed to achieve bile drainage after hepatoportoenterostomy had higher relative levels of FN14 expression.

CONCLUSION

TWEAK/FN14 signaling activation in Prom1 -expressing HPCs contributes to proliferation of profibrogenic ductular reactions in BA.

Patient Selection Approaches in FGFR Inhibitor Trials-Many Paths to the Same End?

Inhibitors of fibroblast growth factor receptor (FGFR) signaling have been investigated in various human cancer diseases. Recently, the first compounds received FDA approval in biomarker-selected patient populations. Different approaches and technologies have been applied in clinical trials, ranging from protein (immunohistochemistry) to mRNA expression (e.g., RNA in situ hybridization) and to detection of various DNA alterations (e.g., copy number variations, mutations, gene fusions). We review, here, the advantages and limitations of the different technologies and discuss the importance of tissue and disease context in identifying the best predictive biomarker for FGFR targeting therapies.

Geographic, climatic, and phylogenetic drivers of variation in colobine activity budgets

Folivorous primates are typically considered time minimizers because the constraints of their unique digestive systems require them to spend a large portion of their activity budgets resting. However, inter- and intraspecific behavioral variation in their activity budgets may be influenced by local geographic and climatic conditions and evolutionary history. We compiled 48 studies representing ten genera, 31 species, and 50 populations to assess geographic (elevation, latitude), climatic (precipitation, temperature), and phylogenetic correlates of colobine activity budgets. Time spent resting negatively correlated with time spent feeding, moving, and socializing. Except for time spent socializing, activity budgets were independent of phylogeny, with more time spent feeding and less time resting in higher-elevation habitats and at lower temperatures. Among the four most common genera in our sample, only in Rhinopithecus did time spent feeding increase with higher elevations (range, 950-3950 m above mean sea level) and lower temperatures (range, 0.9-25 ℃). Only in Trachypithecus did time spent resting decrease with lower temperatures (range, 19-25 ℃). Our findings suggest that there are no apparent effects of geographic or climatic gradients on colobine activity budgets except for Rhinopithecus and Trachypithecus, whose activities are biased in favor of energy maximization rather than time minimization. Compared with other colobines, the ability of Rhinopithecus to adapt their activity budget at high elevations may make them less vulnerable to climate change, while the greater sensitivity of Trachypithecus to heat may make them more vulnerable to climate change.

Frontier progress of the combination of modern medicine and traditional Chinese medicine in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC, accounting for 90% of primary liver cancer) was the sixth most common cancer in the world and the third leading cause of cancer death in 2020. The number of new HCC patients in China accounted for nearly half of that in the world. HCC was of occult and complex onset, with poor prognosis. Clinically, at least 15% of patients with HCC had strong side effects of interventional therapy (IT) and have poor sensitivity to chemotherapy and targeted therapy. Traditional Chinese medicine (TCM), as a multi-target adjuvant therapy, had been shown to play an active anti-tumor role in many previous studies. This review systematically summarized the role of TCM combined with clinically commonly used drugs for the treatment of HCC (including mitomycin C, cyclophosphamide, doxorubicin, 5-fluorouracil, sorafenib, etc.) in the past basic research, and summarized the efficacy of TCM combined with surgery, IT and conventional therapy (CT) in clinical research. It was found that TCM, as an adjuvant treatment, played many roles in the treatment of HCC, including enhancing the tumor inhibition, reducing toxic and side effects, improving chemosensitivity and prolonging survival time of patients. This review summarized the advantages of integrated traditional Chinese and modern medicine in the treatment of HCC and provides a theoretical basis for clinical research.

Role of fibroblast growth factor signalling in hepatic fibrosis

Fibrotic remodelling is a highly conserved protective response to tissue injury and it is essential for the maintenance of structural and functional tissue integrity. Also hepatic fibrosis can be considered as a wound-healing response to liver injury, reflecting a balance between liver repair and scar formation. In contrast, pathological fibrosis corresponds to impaired wound healing. Usually, the liver regenerates after acute injury. However, if the damaging mechanisms persist, the liver reacts with progressive and uncontrolled accumulation of extracellular matrix proteins. Eventually, excessive fibrosis can lead to cirrhosis and hepatic failure. Furthermore, cirrhosis is the major risk factor for the development of hepatocellular cancer (HCC). Therefore, hepatic fibrosis is the most critical pathological factor that determines the morbidity and mortality of patients with chronic liver disease. Still, no effective anti-fibrogenic therapies exist, despite the very high medical need. The regulation of fibroblast growth factor (FGF) signalling is a prerequisite for adequate wound healing, repair and homeostasis in various tissues and organs. The FGF family comprises 22 proteins that can be classified into paracrine, intracrine and endocrine factors. Most FGFs signal through transmembrane tyrosine kinase FGF receptors (FGFRs). Although FGFRs are promising targets for the treatment of HCC, the expression and function of FGFR-ligands in hepatic fibrosis is still poorly understood. This review summarizes the latest advances in our understanding of FGF signalling in hepatic fibrosis. Furthermore, the potential of FGFs as targets for the treatment of hepatic fibrosis and remaining challenges for the field are discussed.

Vascular Adventitial Fibroblasts-Derived FGF10 Promotes Vascular Smooth Muscle Cells Proliferation and Migration in vitro and the Neointima Formation in vivo

Background

Activation of vascular adventitial fibroblasts (VAFs) upon vascular injury contributes greatly to the medial vascular smooth muscle cells (VSMCs) proliferation, migration and the subsequent neointima formation. A number of factors including fibroblast growth factors (FGFs) have been shown to control VSMC growth, proliferation and phenotypic switching, suggesting that they may function as paracrine signals for VAFs to modulate VSMCs functions. However, little is known about the signaling molecule(s) and its mechanism of action. This study is set to identify which and how FGF family members are involved in VAFs mediated vascular remodeling.

Methods

We used qPCR, Western blot and Immunohistochemistry to observe the spatiotemporal expression of FGF10 and FGFR2 in injured vascular tissue. The proliferation and migration assays of VSMCs were performed in a co-culture system. The activation of signaling pathway was detected by Western blot, immunohistochemistry and immunofluorescence. Hematoxylin-eosin and immunofluorescence were used to assess the effects of exogenous FGF10 and siFGF10 on the neointima formation.

Results

The expression of FGF10 and FGFR2 were increased from day 3 through day 14 post injury. FGF10 was significantly upregulated in adventitia, and FGFR2 was detected in both media and neointima after injury. In vitro, FGF10 was most prominently expressed in VAFs and FGFR2 was significantly expressed in VSMCs. Both were regulated by PDGF. Co-culture of VAFs and VSMCs in vitro showed that VAF-derived FGF10 promoted the proliferation and migration of VSMCs. PDGF could synergistically enhance the process. VAF-derived FGF10 can significantly activate the FGFR2 in VSMCs and furthermore significantly activate the downstream MAPK/PI3K-AKT signaling pathways. Delivery of exogenous FGF10 potentiated the neointima formation, while siFGF10 attenuated the neointima formation.

Conclusion

VAFs-derived FGF10 promoted the proliferation and migration of VSMCs and neointima formation, and FGF10-FGFR2 signaling triggered the activation of MAPK/PI3K-AKT pathways in VSMCs and PDGF synergistically amplified FGF10 signaling.

Interplay of autophagy and cancer stem cells in hepatocellular carcinoma

Liver cancer is the sixth most common cancer and the fourth leading cause of cancer deaths in the world. The most common type of liver cancers is hepatocellular carcinoma (HCC). Autophagy is the cellular digestion of harmful components by sequestering the waste products into autophagosomes followed by lysosomal degradation for the maintenance of cellular homeostasis. The impairment of autophagy is highly associated with the development and progression of HCC although autophagy may be involved in tumour-suppressing cellular events. In regards to its protecting role, autophagy also shelters the cells from anoikis- a programmed cell death in anchorage-dependent cells detached from the surrounding extracellular matrix which facilitates metastasis in HCC. Liver cancer stem cells (LCSCs) have the ability for self-renewal and differentiation and are associated with the development and progression of HCC by regulating stemness, resistance and angiogenesis. Interestingly, autophagy is also known to regulate normal stem cells by promoting cellular survival and differentiation and maintaining cellular homeostasis. In this review, we discuss the basal autophagic mechanisms and double-faceted roles of autophagy as both tumour suppressor and tumour promoter in HCC, as well as its association with and contribution to self-renewal and differentiation of LCSCs.

Genome-wide characterization and expression analysis of pseudo-response regulator gene family in wheat

Pseudo-response regulator (PRR) gene family members play a significant role in plant circadian clocks, flowering time inflorescence architecture development during transition from vegetative growth phase to reproductive phase. In current study, we analyzed the expression profiling, phylogenetic relationship, and molecular characterization of PRR gene family members of common wheat by using IWGSC Ref seq v1.1 wheat genome database with a coverage rate of 90%. By using bioinformatic approach total 20 candidate gene sequences were identified and divided into six groups and four clades. It was found that mostly genes have same number of exons and introns showed similar features because they originated through duplication events during evolution processes. Although all the proteins have conserved PRR domains, but some are distinct in their sequences suggesting functional divergence. By comparative synteny analysis it was revealed that Group 1, 2, 3 and 11-D of group 4 have duplication events while group 5 and TaPRR9-B,10-D showed conservation with previously identified PRR members from rice. While expression variation of six groups from each analysis matches with each other. Five groups highly expressed in leaf, spike, and roots in pattern like leaf > spike > root at all three stages booting, heading and anthesis of spike development. This suggests that TaPRR genes play important roles in different photoperiod signaling pathways in different organs at different stages of spike development and flowering via unknown pathway. These findings will also provide comprehensive knowledge about future investigations on wheat PRR family members involved in complex network of circadian system for plant development.

Associations between SNP83 of phosphodiesterase 4D gene and carotid atherosclerosis in a southern Chinese Han population: a case-control study

Atherosclerosis was an important pathophysiological basis of atherothrombotic stroke, and phosphodiesterase 4D (PDE4D) polymorphism (SNP83/rs966221) was reported to be associated with the susceptibility to atherothrombotic stroke. Aim of the present study was to explore the potential association between SNP83 and carotid atherosclerosis (CAS). 204 southern Chinese Han participants were divided into two groups according to the carotid intima-media thickness (IMT) of the carotid artery: CAS group (carotid IMT ≥ 1.0 mm) and non-CAS group (carotid IMT < 1.0 mm). Carotid IMT was measured by color Doppler ultrasound. The PDE4D SNP83 polymorphism was determined by SNaPshot technique. Our study found that SNP83 was associated significantly with CAS susceptibility under the dominant, overdominant and codominant models. After adjusting for age, gender, low-density lipoprotein cholesterol, Hemoglobin A1c, cigarette smoking, hypertension history, and diabetes mellitus history, the association still remained significant (dominant model: crude OR = 2.373, 95% CI: 1.268-4.442, P = 0.007; adjusted OR = 3.129, 95% CI: 1.104-8.866, P = 0.032; overdominant model: crude OR = 1.968, 95% CI: 1.043-3.714, P = 0.037; adjusted OR = 2.854, 95% CI: 1.005-8.108, P = 0.049; codominant: crude OR = 2.102, 95% CI: 1.110-3.979, P = 0.023; adjusted OR = 2.984, 95% CI: 1.047-8.502, P = 0.041). Carotid IMT of carriers with CT + CC genotypes was higher than carriers with TT genotype (P = 0.016). Our results indicated that the SNP83/rs966221 located on PDE4D gene was significantly associated between CAS susceptibility and carotid IMT independently of conventional risk factors in a southern Chinese Han population.

IRF2 regulates cellular survival and Lenvatinib-sensitivity of hepatocellular carcinoma (HCC) through regulating β-catenin

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IRF2 and β-catenin are highly expressed in HCC tissues.

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IRF2 upregulation of β-catenin promotes HCC cell proliferation.

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IRF2 enhances lenvatinib resistance in HCC cells.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Lenvatinib oral chemotherapy is approved as a first-line treatment of patients with unresectable HCC. The efficacy and therapeutic duration of lenvatinib are limited by drug resistance, and the mechanism is unclear. IRF2 is a constitutive transcription factor associated with the development of various cancers by regulating cancer cell growth, apoptosis, and drug resistance. However, the potential role of IRF2 in lenvatinib resistance in HCC has not been explored. In this study, we found that IRF2 promoted proliferation, inhibited apoptosis, and increased lenvatinib resistance of HCC cells by regulating β-catenin expression. Silencing IRF2 downregulated the expression of β-catenin, while overexpressing IRF2 upregulated β-catenin. Moreover, the expression of β-catenin and IRF2 was positively correlated in HCC tissues. Inhibiting β-catenin with XAV-939 effectively abrogated β-catenin expression caused by lenvatinib treatment. These findings identify an important function of IRF2 in HCC and demonstrate a mechanism of lenvatinib resistance of HCC cells. Targeting IRF2 may be a potential strategy to improve the therapeutic effect of lenvatinib on HCC.

Typing FGFR2 translocation determines the response to targeted therapy of intrahepatic cholangiocarcinomas

Chromosomal translocations involving fibroblast growth factor receptor 2 (FGFR2) gene at the breakpoints are common genetic lesions in intrahepatic cholangiocarcinoma (ICC) and the resultant fusion protein products have emerged as promising druggable targets. However, predicting the sensitivity of FGFR2 fusions to FGFR kinase inhibitors is crucial to the prognosis of the ICC-targeted therapy. Here, we report identification of nine FGFR2 translocations out of 173 (5.2%) ICC tumors. Although clinicopathologically these FGFR2 translocation bearing ICC tumors are indistinguishable from the rest of the cohort, they are invariably of the mass-forming type originated from the small bile duct. We show that the protein products of FGFR2 fusions can be classified into three subtypes based on the breaking positions of the fusion partners: the classical fusions that retain the tyrosine kinase (TK) and the Immunoglobulin (Ig)-like domains (n = 6); the sub-classical fusions that retain only the TK domain without the Ig-like domain (n = 1); and the non-classical fusions that lack both the TK and Ig-like domains (n = 2). We demonstrate that cholangiocarcinoma cells engineered to express the classical and sub-classical fusions show sensitivity to FGFR-specific kinase inhibitors as evident by the suppression of MAPK/ERK and AKT/PI3K activities following the inhibitor treatment. Furthermore, the kinase-deficient mutant of the sub-classical fusion also lost its sensitivity to the FGFR-specific inhibitors. Taken together, our study suggests that it is essential to determine the breakpoint and type of FGFR2 fusions in the small bile duct subtype of ICC for the targeted treatment.

Ribociclib enhances infigratinib-induced cancer cell differentiation and delays resistance in FGFR-driven hepatocellular carcinoma

BACKGROUND & AIMS

Infigratinib is a pan-FGFR (fibroblast growth factor receptor) inhibitor that has shown encouraging activity in FGFR-dependent hepatocellular carcinoma (HCC) models. However, long-term treatment results in the emergence of resistant colonies. We sought to understand the mechanisms behind infigratinib-induced tumour cell differentiation and resistance and to explore the potential of adding the CDK4/6 inhibitor ribociclib to prolong cell differentiation.

METHODS

Nine high and three low FGFR1-3-expressing HCC patient-derived xenograft (PDX) tumours were subcutaneously implanted into SCID mice and subsequently treated with either infigratinib alone or in combination with ribociclib. Tumour tissues were then subjected to immunohistochemistry to assess cell differentiation, as indicated by the cytoplasmic-to-nuclear ratio and markers such as CYP3A4, HNF4α and albumin. Western blot analyses were performed to investigate the signalling pathways involved.

RESULTS

Infigratinib induced cell differentiation in FGFR1-3-dependent HCC PDX models, as indicated by an increase in the cytoplasmic/nuclear ratio and an increase in CYP3A4, HNF4α and albumin. Resistant colonies emerged in long-term treatment, characterised by a reversal of differentiated cell morphology, a reduction in the cytoplasmic-to-nuclear ratio and a loss of differentiation markers. Western blot analyses identified an increase in the CDK4/Cdc2/Rb pathway. The addition of ribociclib effectively blocked this pathway and reversed resistance to infigratinib, resulting in prolonged cell differentiation and growth inhibition.

CONCLUSIONS

Our findings demonstrate that the combined inhibition of FGFR/CDK4/6 pathways is highly effective in providing long-lasting tumour growth inhibition and cell differentiation and reducing drug resistance. Therefore, further clinical investigations in patients with FGFR1-3-dependant HCC are warranted.

SHARPIN: Role in Finding NEMO and in Amyloid-Beta Clearance and Degradation (ABCD) Pathway in Alzheimer's Disease?

SHANK- associated RH domain-interacting protein (SHARPIN) is a multifunctional protein associated with numerous physiological functions and many diseases. The primary role of the protein as a LUBAC-dependent component in regulating the activation of the transcription factor NF-κB accounts to its role in inflammation and antiapoptosis. Hence, an alteration of SHARPIN expression or genetic mutations or polymorphisms leads to the alteration of the above-mentioned primary physiological functions contributing to inflammation-associated diseases and cancer, respectively. However, there are complications of targeting SHARPIN as a therapeutic approach, which arises from the wide-range of LUBAC-independent functions and yet unknown roles of SHARPIN including neuronal functions. The identification of SHARPIN as a postsynaptic protein and the emerging studies indicating its role in several neurodegenerative diseases including Alzheimer's disease suggests a strong role of SHARPIN in neuronal functioning. This review summarizes the functional roles of SHARPIN in normal physiology and disease pathogenesis and strongly suggests a need for concentrating more studies on identifying the unknown neuronal functions of SHARPIN and hence its role in neurodegenerative diseases.

The Emerging Roles of Cancer Stem Cells and Wnt/Beta-Catenin Signaling in Hepatoblastoma

Hepatoblastoma (HB) is the most common form of primary liver malignancy found in pediatric populations. HB is considered to be clonal and arises from hepatoblasts, or embryonic liver progenitor cells. These less differentiated tumor-initiating progenitor cells, or cancer stem cells (CSCs), may contribute to tumor recurrence and resistance to therapies, and have high metastatic abilities. Phenotypic heterogeneity, undesired genetic and epigenetic alterations, and dysregulated signaling pathways provide CSCs with a survival advantage over current therapies. The molecular and cellular basis of HB and the mechanism of CSC induction are not fully understood. The Wnt/beta-catenin pathway is one of the major developmental pathways and is believed to play an important role in the pathogenesis of HB and CSC formation. This review summarizes the cellular and molecular characteristics of HB with a specific emphasis on CSCs and Wnt/beta-catenin signaling.

MicroRNA-145 Regulates the Differentiation of Adipose Stem Cells Toward Microvascular Endothelial Cells and Promotes Angiogenesis

RATIONALE

Adipose-derived stem cells (ASCs) are a potential adult mesenchymal stem cell source for restoring endothelial function in ischemic tissues. However, the mechanism that promotes ASCs differentiation toward endothelial cells (ECs) is not known.

OBJECTIVE

To investigate the mechanisms of ASCs differentiation into ECs.

METHODS AND RESULTS

ASCs were isolated from clinical lipoaspirates and cultured with DMEM or endothelial cell-conditioned medium. Endothelial cell-conditioned medium induced downregulation of miR-145 in ASCs and promoted endothelial differentiation. We identified bFGF (basic fibroblast growth factor) released by ECs as inducer of ASCs differentiation through receptor-induced AKT (protein kinase B) signaling and phosphorylation of FOXO1 (forkhead box protein O1) suppressing its transcriptional activity and decreasing miR-145 expression. Blocking bFGF-receptor or PI3K/AKT signaling in ASCs increased miR-145 levels. Modulation of miR-145 in ASCs, using a miR-145 inhibitor, regulated their differentiation into ECs: increasing proliferation, migration, inducing expression of EC markers (VE-cadherin, VEGFR2 [vascular endothelial growth factor receptor 2], or VWF [von Willebrand Factor]), and tube-like formation. Furthermore, in vivo, downregulation of miR-145 in ASCs enhanced angiogenesis in subcutaneously implanted plugs in mice. In a murine hindlimb ischemia model injection of ASCs with downregulated miR-145 induced collateral flow and capillary formation evidenced by magnetic resonance angiography. Next, we identified ETS1 (v-ets avian erythroblastosis virus E26 oncogene homolog 1) as the target of miR-145. Upregulation of miR-145 in ASCs, by mimic miR-145, suppressed ETS1 expression and consequently abolished EC differentiation and the angiogenic properties of endothelial cell-conditioned medium-preconditioned ASCs; whereas, overexpression of ETS1 reversed the abrogated antiangiogenic capacity of miR-145. ETS1 overexpression induced similar results to those obtained with miR-145 knockdown.

CONCLUSIONS

bFGF released by ECs induces ASCs differentiation toward ECs through miR-145-regulated expression of ETS1. Downregulation of miR-145 in ASCs induce vascular network formation in ischemic muscle.

Prominin-1 Promotes Biliary Fibrosis Associated With Biliary Atresia

In patients with biliary atresia (BA), the extent of intrahepatic biliary fibrosis negatively correlates with successful surgical bypass of the congenital cholangiopathy as well as subsequent transplant-free survival. We recently linked the expansion of a population of prominin-1 (Prom1)-expressing hepatic progenitor cells to biliary fibrogenesis. Herein, we hypothesized that Prom1-expressing progenitor cells play a role in BA-associated fibrosis. Rhesus rotavirus (RRV)-mediated experimental BA was induced in newborn mice homozygous for the transgene Prom1^{cre-ert2-nlacz} , which was knocked in to the Prom1 gene locus, thus creating functional Prom1 knockout (KO) mice, and their wildtype (WT) littermates. Clinical data and tissue samples from BA infants from the Childhood Liver Disease Research Consortium were analyzed. Extrahepatic biliary obliteration was present in both WT and KO mice; there was no difference in serum total bilirubin (TBili) levels. The intrahepatic periportal expansion of the PROM1^pos cell population, typically observed in RRV-induced BA, was absent in KO mice. RRV-treated KO mice demonstrated significantly fewer cytokeratin-19 (CK19)-positive ductular reactions (P = 0.0004) and significantly less periportal collagen deposition (P = 0.0001) compared with WT. RRV-treated KO mice expressed significantly less integrin-β6, which encodes a key biliary-specific subunit of a transforming growth factor (TGF) β activator (P = 0.0004). Infants with successful biliary drainage (Tbili ≤1.5 mg/dL within 3 months postoperatively), which is highly predictive of increased transplant-free survival, expressed significantly less hepatic PROM1, CK19, and COLLAGEN-1α compared with those with TBili >1.5 (P < 0.05). Conclusion: Prom1 plays an important role in biliary fibrogenesis, in part through integrin-mediated TGF pathway activation.

The role of fibroblast growth factor 1 and 2 on the pathological behavior of valve interstitial cells in a three-dimensional mechanically-conditioned model

Background

More than five million Americans suffer from heart valve disease annually, a condition that worsens cardiac function and gradually leads to heart failure if appropriate treatment is not performed on time. Currently no medication can cure heart valve disease, leaving surgical intervention as the only viable option for patients at late stages of cardiac valve disease. Tremendous efforts have been undertaken to elucidate how resident cells in the valves respond to pathological stimulation as well as the underlying mechanisms that regulate these responses, to identify potential therapeutic targets for non-surgical treatment of valvular heart disease.

Results

Cardiac valve interstitial cells (VICs) naturally reside in a complex three-dimensional environment under varying hemodynamics, which is difficult to replicate in vitro. As a result, most cell signaling studies in the field have traditionally been conducted on two-dimensional models or in the absence of hemodynamic forces. Previously, we reported the fabrication of a hydrogel scaffold that could be used to culture valve cells under dynamic mechanical stimulation in a valve-mimetic environment. This model, therefore appeared to be suitable for VIC signaling studies as it provided cells a three-dimensional environment with the ability to incorporate mechanical stretching stimulation. Utilizing this model, we investigated the possible role of fibroblast growth factor 1 and 2 (FGF1 and FGF2) via FGFR1 receptor signaling in regulating valve cell activation under physiological (10% stretch) and pathological (20% stretch) mechanical conditions as well as in mediating cell proliferation and metabolism via the Akt/mTOR pathways. We reported that 1) FGF1 and FGF2 treatment was able to maintain the quiescent phenotype of VICs; 2) Cells increased proliferation as determined by optical redox ratios under elevated cyclic stretch via Akt/mTOR pathways; and 3) FGF1 and 2 signaling via the FGFR1 reduced VIC proliferation and activation under elevated cyclic stretch conditions.

Conclusions

Overall, these results suggested that targeting FGFR1 receptor signaling may represent a possible therapeutic strategy for preventing heart valve disease progression.

Electronic supplementary material

The online version of this article (10.1186/s13036-019-0168-1) contains supplementary material, which is available to authorized users.

Regulation of FGF10 Signaling in Development and Disease

Fibroblast Growth Factor 10 (FGF10) is a multifunctional mesenchymal-epithelial signaling growth factor, which is essential for multi-organ development and tissue homeostasis in adults. Furthermore, FGF10 deregulation has been associated with human genetic disorders and certain forms of cancer. Upon binding to FGF receptors with heparan sulfate as co-factor, FGF10 activates several intracellular signaling cascades, resulting in cell proliferation, differentiation, and invasion. FGF10 activity is modulated not only by heparan sulfate proteoglycans in the extracellular matrix, but also by hormones and other soluble factors. Despite more than 20 years of research on FGF10 functions, context-dependent regulation of FGF10 signaling specificity remains poorly understood. Emerging modes of FGF10 signaling regulation will be described, focusing on the role of FGF10 trafficking and sub-cellular localization, heparan sulfate proteoglycans, and miRNAs. Systems biology approaches based on quantitative proteomics will be considered for globally investigating FGF10 signaling specificity. Finally, current gaps in our understanding of FGF10 functions, such as the relative contribution of receptor isoforms to signaling activation, will be discussed in the context of genetic disorders and tumorigenesis.

Inhibition of CREB binding protein-beta-catenin signaling down regulates CD133 expression and activates PP2A-PTEN signaling in tumor initiating liver cancer cells

Background

The WNT-beta-catenin pathway is known to regulate cellular homeostasis during development and tissue regeneration. Activation of WNT signaling increases the stability of cytoplasmic beta-catenin and enhances its nuclear translocation. Nuclear beta-catenin function is regulated by transcriptional co-factors such as CREB binding protein (CBP) and p300. Hyper-activated WNT-beta-catenin signaling is associated with many cancers. However, its role in inducing stemness to liver cancer cells, its autoregulation and how it regulates tumor suppressor pathways are not well understood. Here we have investigated the role of CBP-beta-catenin signaling on the expression of CD133, a known stem cell antigen and PP2A-PTEN pathway in tumor initiating liver cancer cells.

Methods

Human hepatoblastoma cell line HepG2 and clonally expanded CD133 expressing tumor initiating liver cells (TICs) from premalignant murine liver were used in this study. CBP-beta-catenin inhibitor ICG001 was used to target CBP-beta catenin signaling in liver cancer cells in vitro. Western blotting and real time PCR (qPCR) were used to quantify protein expression/phosphorylation and mRNA levels, respectively. CBP and CD133 gene silencing was performed by siRNA transfection. Fluorescence Activated Cell Sorting (FACS) was performed to quantify CD133 positive cells. Protein Phosphatase (PP2A) activity was measured after PP2AC immunoprecipitation.

Results

CBP inhibitor ICG001 and CBP silencing significantly reduced CD133 expression and anchorage independent growth in HepG2 and murine TICs. CD133 silencing in TICs decreased cell proliferation and expression levels of cell cycle regulatory genes, CyclinD1 and CyclinA2. ICG001 treatment and CBP silencing reduced the levels of phospho^{Ser380/Tyr382/383}PTEN, phospho^Ser473-AKT, Phospho-^Ser552beta-catenin in TICs. ICG001 mediated de-phosphorylation of PTEN in TICs was PP2A dependent and partly prevented by co-treatment with PP2A inhibitor okadaic acid.

Conclusions

CBP-beta-catenin signaling promotes stemness via CD133 induction and cell proliferation in TICs. We found a novel functional link between CBP-beta-catenin and PP2A-PTEN-AKT pathway in liver TICs. Therefore, CBP-beta-catenin-PP2A-PTEN-AKT signaling axis could be a novel therapeutic target to prevent liver tumor initiation and cancer recurrence.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0222-5) contains supplementary material, which is available to authorized users.

Wnt Signaling in Stem Cells and Cancer Stem Cells: A Tale of Two Coactivators

Wnt signaling in stem cells plays critical roles in development, normal adult physiology, and disease. In this chapter, we focus on the role of the Wnt signaling pathway in somatic stem cell biology and its critical role in normal tissue homeostasis and cancer. Wnt signaling can both maintain potency and initiate differentiation in somatic stem cells, depending on the cellular and environmental context. Based principally on studies from our lab, we will explain the dichotomous behavior of this signaling pathway in determining stem cell fate decisions, placing special emphasis on the interaction of β-catenin with either of the two highly homologous Kat3 coactivator proteins, CBP and p300. We will also discuss our results, both preclinical and clinical, demonstrating that small molecule modulators of the β-catenin/Kat3 coactivator interaction can be safely utilized to shift the balance between maintenance of potency and initiation of differentiation.

Aging of Human Adult Stem Cells

With the continuous development of stem cell research in recent years, it is realized that stem cell aging may be the core issue of organ aging. As an important approach and main content of regenerative medicine, the stem cell research brings great hope to overcome difficult diseases and improve the quality of life for human beings and become the key to solve this issue. Based on this research, the varying characteristics of stem cells in aging could be recognized; the role of stem cells in the organ aging and regeneration will be revealed; the function of stem cells will be controllable and regulatable in tissues and organs; the stem cells from tissues and organs with rapid or slow cell renewal (e.g., liver and neuron) could be continuously observed from the levels of cellular molecules and dynamic complex. With the assistance of systematical research approaches, the function and mechanism studies can be conducted via multi-perspectives and levels during the different stages of organ aging and regeneration. All of the abovementioned requires great efforts to thoroughly understand the basic rule and the way of stem cell regulation in organ aging and regeneration. Final to the end, the dream of antiaging, efficient repair, and organ remodeling could be realized and also can meet the major needs of population health and disease treatment in our country, meaningfully to contribute benefits for the health of human beings.

Akt Activation Mediates Acquired Resistance to Fibroblast Growth Factor Receptor Inhibitor BGJ398

Activation of FGFR signaling through mutations, amplifications, or fusions involving FGFR1, 2, 3, or 4 is seen in multiple tumors, including lung, bladder, and cholangiocarcinoma. Currently, several clinical trials are evaluating the role of novel FGFR inhibitors in solid tumors. As we move forward with FGFR inhibitors clinically, we anticipate the emergence of resistance with treatment. Consequently, we sought to study the mechanism(s) of acquired resistance to FGFR inhibitors using annotated cancer cell lines. We identified cancer cell lines that have activating mutations in FGFR1, 2, or 3 and treated them chronically with the selective FGFR inhibitor, BGJ398. We observed resistance to chronic BGJ398 exposure in DMS114 (small-cell lung cancer, FGFR1 amplification) and RT112 (urothelial carcinoma, FGFR3 fusion/amplification) cell lines based on viability assays. Reverse-phase protein array (RPPA) analysis showed increased phosphorylation of Akt (T308 and S473) and its downstream target GSK3 (S9 and S21) in both the resistant cell lines when compared with matching controls. Results of RPPA were confirmed using immunoblots. Consequently, the addition of an Akt inhibitor (GSK2141795) or siRNA was able to restore sensitivity to BGJ398 in resistant cell lines. These data suggest a role for Akt pathway in mediating acquired resistance to FGFR inhibition. Mol Cancer Ther; 16(4); 614-24. ©2017 AACR.

Hepatic Prominin-1 expression is associated with biliary fibrosis

BACKGROUND

Intrahepatic biliary fibrosis, as seen with cholestatic liver injuries such as biliary atresia, is mechanistically distinct from fibrosis caused by hepatocyte toxicity. We previously demonstrated the expansion of cells expressing the stem/progenitor cell marker Prominin-1, within regions of developing fibrosis in biliary atresia. Thus, we hypothesized that Prominin-1 expression is biliary fibrosis-specific.

METHODS

Gene expression of Prominin-1 was analyzed in adult mice undergoing either cholestatic bile duct ligation or hepatotoxic carbon tetrachloride administration by quantitative polymerase chair reaction. Lineage tracing of Prominin-1-expressing cells and Collagen-1α-expressing cells was performed after bile duct ligation in Prominin-1^{cre-ert2-lacz};Gfp^lsl and Collagen-1α^Gfp transgenic mice, respectively.

RESULTS

Prominin-1 expression increased significantly after bile duct ligation compared with sham (6.6 ± 0.9-fold change at 2 weeks, P < .05) but not with carbon tetrachloride (-0.7 ± 0.5-fold change, not significant). Upregulation of Prominin-1 was observed histologically throughout the liver as early as 5 days after bile duct ligation in Prominin-1^{cre-ert2-lacz} mice by LacZ staining in nonhepatocyte cells. Lineage tracing of Prominin-1-expressing cells labeled prior to bile duct ligation in Prominin-1^{cre-ert2-lacz};Gfp^lsl mice, demonstrated increasing colocalization of GREEN FLUORESCENT PROTEIN with biliary marker CYTOKERATIN-19 within ductular reactions up to 5 weeks after bile duct ligation consistent with biliary transdifferentiation. In contrast, rare colocalization of GREEN FLUORESCENT PROTEIN with mesenchymal marker α-SMOOTH MUSCLE ACTIN in Prominin-1^{cre-ert2-lacz};Gfp^lsl mice and some colocalization of GREEN FLUORESCENT PROTEIN with PROMININ-1 in Collagen-1α^Gfp mice, indicate minimal contribution of Prominin-1 progenitor cells to the pool of collagen-producing myofibroblasts.

CONCLUSION

During biliary fibrosis Prominin-1-expressing progenitor cells transdifferentiate into cells within ductular reactions. This transdifferentiation may promote fibrosis.

The WNT-less wonder: WNT-independent β-catenin signaling

β-catenin is known as an Armadillo protein that regulates gene expression following WNT pathway activation. However, WNT-independent pathways also activate β-catenin. During the establishment of the melanocyte lineage, β-catenin plays an important role. In the context of physiopathology, β-catenin is activated genetically or transiently in various cancers, including melanoma, where it can be found in the nucleus of tumors. In this review, we discuss alternative pathways that activate β-catenin independent of WNTs and highlight what is known regarding these pathways in melanoma. We also discuss the role of β-catenin as a transcriptional regulator in various cell types, with emphasis on the different transcription factors it associates with independent of WNT induction. Finally, the role of WNT-independent β-catenin in melanocyte development and melanomagenesis is also discussed.

Toll-like receptor 3 mediates PROMININ-1 expressing cell expansion in biliary atresia via Transforming Growth Factor-Beta

BACKGROUND

In biliary atresia (BA), epithelial-mesenchymal hepatic progenitor cells (HPC) expressing the stem/progenitor cell marker PROMININ-1 (PROM1) undergo expansion and subsequent transdifferentiation into collagen-producing myofibroblasts within regions of evolving biliary fibrosis under the regulation of Transforming Growth Factor-β (TGFβ) signaling. We hypothesized that pro-inflammatory Toll-like Receptor-3 (TLR3) signal activation promotes the differentiation of PROM1+ HPC via TGFβ pathway activation in vitro.

METHODS

PROM1+ Mat1a(-/-) HPC were treated with a double-stranded RNA analog, polyionosinic-polycytidylic acid (Poly I:C), ± small molecule inhibitors nafamostat, or SB431542.

RESULTS

Poly I:C induced myofibroblastic-like morphologic changes, degradation of IκB-α consistent with TLR3-NFκB activation, a 15-fold increase in the expression of Vimentin, a 9-fold increase in Collagen-1a, a 4.6-fold increase in Snail at 24h (p<0.05), and an 8.2-fold increase in Prom1 at 72h (p<0.0001) by qPCR. Immunofluorescence demonstrated nuclear phosphorylated SMAD3, TLR3, and COLLAGEN-1α staining following Poly I:C treatment. Degradation of IκBα was inhibited by nafamostat. Co-treatment with either nafamostat or SB431542 blocked the morphologic change and abrogated the increased expression of Cd133, Collagen, Vimentin, and Snail1.

CONCLUSIONS

TLR3 activation induces myofibroblastic differentiation of PROM1+ HPC in part via TGFβ pathway activation to promote BA-associated biliary fibrosis.

APC haploinsufficiency coupled with p53 loss sufficiently induces mucinous cystic neoplasms and invasive pancreatic carcinoma in mice

Adenomatous polyposis coli (APC), a tumor-suppressor gene critically involved in familial adenomatous polyposis, is integral in Wnt/β-catenin signaling and is implicated in the development of sporadic tumors of the distal gastrointestinal tract including pancreatic cancer (PC). Here we report for the first time that functional APC is required for the growth and maintenance of pancreatic islets and maturation. Subsequently, a non-Kras mutation-induced premalignancy mouse model was developed; in this model, APC haploinsufficiency coupled with p53 deletion resulted in the development of a distinct type of pancreatic premalignant precursors, mucinous cystic neoplasms (MCNs), exhibiting pathomechanisms identical to those observed in human MCNs, including accumulation of cystic fluid secreted by neoplastic and ovarian-like stromal cells, with 100% penetrance and the presence of hepatic and gastric metastases in >30% of the mice. The major clinical implications of this study suggest targeting the Wnt signaling pathway as a novel strategy for managing MCN.

p300/β-Catenin Interactions Regulate Adult Progenitor Cell Differentiation Downstream of WNT5a/Protein Kinase C (PKC)

Maintenance of stem/progenitor cell-progeny relationships is required for tissue homeostasis during normal turnover and repair. Wnt signaling is implicated in both maintenance and differentiation of adult stem/progenitor cells, yet how this pathway serves these dichotomous roles remains enigmatic. We previously proposed a model suggesting that specific interaction of β-catenin with either of the homologous Kat3 co-activators, p300 or CREB-binding protein, differentially regulates maintenance versus differentiation of embryonic stem cells. Limited knowledge of endogenous mechanisms driving differential β-catenin/co-activator interactions and their role in adult somatic stem/progenitor cell maintenance versus differentiation led us to explore this process in defined models of adult progenitor cell differentiation. We focused primarily on alveolar epithelial type II (AT2) cells, progenitors of distal lung epithelium, and identified a novel axis whereby WNT5a/protein kinase C (PKC) signaling regulates specific β-catenin/co-activator interactions to promote adult progenitor cell differentiation. p300/β-catenin but not CBP/β-catenin interaction increases as AT2 cells differentiate to a type I (AT1) cell-like phenotype. Additionally, p300 transcriptionally activates AT1 cell-specific gene Aqp-5. IQ-1, a specific inhibitor of p300/β-catenin interaction, prevents differentiation of not only primary AT2 cells, but also tracheal epithelial cells, and C2C12 myoblasts. p300 phosphorylation at Ser-89 enhances p300/β-catenin interaction, concurrent with alveolar epithelial cell differentiation. WNT5a, a traditionally non-canonical WNT ligand regulates Ser-89 phosphorylation and p300/β-catenin interactions in a PKC-dependent manner, likely involving PKCζ. These studies identify a novel intersection of canonical and non-canonical Wnt signaling in adult progenitor cell differentiation that has important implications for targeting β-catenin to modulate adult progenitor cell behavior in disease.

Protein-protein interactions among signaling pathways may become new therapeutic targets in liver cancer (Review)

Numerous signaling pathways have been shown to be dysregulated in liver cancer. In addition, some protein-protein interactions are prerequisite for the uncontrolled activation or inhibition of these signaling pathways. For instance, in the PI3K/AKT signaling pathway, protein AKT binds with a number of proteins such as mTOR, FOXO1 and MDM2 to play an oncogenic role in liver cancer. The aim of the present review was to focus on a series of important protein-protein interactions that can serve as potential therapeutic targets in liver cancer among certain important pro-carcinogenic signaling pathways. The strategies of how to investigate and analyze the protein-protein interactions are also included in this review. A survey of these protein interactions may provide alternative therapeutic targets in liver cancer.

Wnt blockers inhibit the proliferation of lung cancer stem cells

Background

Previous study has confirmed that the occurrence of Wnt pathway activation is associated with risk of non-small-cell lung cancer recurrence. However, whether the pharmacologic blocking of the Wnt signaling pathway could provide therapeutic possibility remains unknown. The aim of the present study was to evaluate the therapeutic functions of the Wnt signaling pathway inhibitor pyrvinium pamoate (PP) on lung cancer stem cells (LCSCs) in vitro.

Methods

Colony formation and sphere culture were performed to enrich LCSCs from three lung cancer cell lines: PC9, SPC-A1, and A549. After confirming stemness by immunofluorescence, PP was employed for cell viability assay by comparison with three other kinds of Wnt signaling inhibitor: salinomycin, ICG-001, and silibinin. The effect of PP on LCSCs was further verified by colony formation assay and gene expression analysis.

Results

LCSCs were successfully generated by sphere culture from SPC-A1 and PC9 cells, but not A549 cells. Immunofluorescence assay showed that LCSCs could express pluripotent stem cell markers, including NANOG, Oct4, KLF5, and SOX2, and Wnt signaling pathway molecules β-catenin and MYC. Half-maximal inhibitory concentrations of PP on SPC-A1, PC9, and A549 were 10 nM, 0.44 nM, and 0.21 nM, respectively, which are much lower than those of salinomycin, ICG-001, and silibinin. Moreover, significantly decreased colony formation and downregulation of pluripotent stem cell signaling pathway were observed in lung cancer cells after treatment with PP.

Conclusion

Wnt signaling inhibitor PP can inhibit proliferation of LCSCs, and the Wnt signaling pathway could be considered a promising therapeutic or interventional target in lung adenocarcinoma.

Expansion of prominin-1-expressing cells in association with fibrosis of biliary atresia

Biliary atresia (BA), the most common cause of end-stage liver disease and the leading indication for pediatric liver transplantation, is associated with intrahepatic ductular reactions within regions of rapidly expanding periportal biliary fibrosis. Whereas the extent of such biliary fibrosis is a negative predictor of long-term transplant-free survival, the cellular phenotypes involved in the fibrosis are not well established. Using a rhesus rotavirus-induced mouse model of BA, we demonstrate significant expansion of a cell population expressing the putative stem/progenitor cell marker, PROMININ-1 (PROM1), adjacent to ductular reactions within regions of periportal fibrosis. PROM1positive (pos) cells express Collagen-1α1. Subsets of PROM1pos cells coexpress progenitor cell marker CD49f, epithelial marker E-CADHERIN, biliary marker CYTOKERATIN-19, and mesenchymal markers VIMENTIN and alpha-SMOOTH MUSCLE ACTIN (αSMA). Expansion of the PROM1pos cell population is associated with activation of Fibroblast Growth Factor (FGF) and Transforming Growth Factor-beta (TGFβ) signaling. In vitro cotreatment of PROM1-expressing Mat1a-/- hepatic progenitor cells with recombinant human FGF10 and TGFβ1 promotes morphologic transformation toward a myofibroblastic cell phenotype with increased expression of myofibroblastic genes Collagen-1α1, Fibronectin, and α-Sma. Infants with BA demonstrate similar expansion of periportal PROM1pos cells with activated Mothers Against Decapentaplegic Homolog 3 (SMAD3) signaling in association with increased hepatic expression of FGF10, FGFR1, and FGFR2 as well as mesenchymal genes SLUG and SNAIL. Infants with perinatal subtype of BA have higher tissue levels of PROM1 expression than those with embryonic subtype.

CONCLUSION

Expansion of collagen-producing PROM1pos cells within regions of periportal fibrosis is associated with activated FGF and TGFβ pathways in both experimental and human BA. PROM1pos cells may therefore play an important role in the biliary fibrosis of BA.

CMV-induced pathology: pathway and gene-gene interaction analysis

Mucoepidermoid carcinoma (MEC) is the most prevalent malignant tumor in major and minor salivary glands (SGs). We have recently identified human cytomegalovirus (hCMV) as a principle component in the multifactorial causation of SG-MEC. This finding is corroborated by the ability of the purified mouse CMV (mCMV) to induce malignant transformation of SG cells in a three-dimensional in vitro mouse model, using a similar oncogenic signaling pathway. Our prior studies indicate that the core tumor microenvironment (TME) is a key regulator of pathologic progression, particularly the cancer-associated fibroblast (CAF) component. Studies of early CAFs immunodetect aberrant expression of ECM components, as well as multiple growth factors, cytokines and transcription factors. Here we present the mechanistic insight derived from a mathematical structure ("wiring diagram") used to model complex relationships between a highly relevant (p=9.43×10(-12)) global "cancer network" of 32 genes and their known links. Detailed characterization of the functional architecture of the examined "cancer network" exposes the critical crosstalk and compensatory pathways that limit the efficacy of targeted anti-kinase therapies.

Crosstalk between DNA repair and cancer stem cell (CSC) associated intracellular pathways

DNA damaging agents (ionizing radiation and chemotherapeutics) are considered as most effective in cancer treatment. However, there is a subpopulation of carcinoma cells within the tumour demonstrating resistance to DNA damaging treatment approaches. It is suggested that limited tumour response to this kind of therapy can be associated with specific molecular properties of carcinoma stem cells (CSCs) representing the most refractory cell subpopulation. This review article presents novel data about molecular features of CSCs underlying DNA damage response and related intracellular signalling.

Fibroblast growth factor family as a potential target in the treatment of hepatocellular carcinoma

Hepatocellular cancer (HCC) is currently the third leading cause of cancer death worldwide. The prognosis of patients diagnosed with late-stage disease is dismal due to high resistance to conventional systemic therapies. The introduction of sorafenib, despite its limited efficacy, as the standard systemic therapy for advanced HCC has paved a way for targeted molecular therapies for HCC. Fibroblast growth factor (FGF) signaling plays an important role in the developing embryo and the adult. The FGF signaling pathway is often hijacked by cancer cells, including HCC. Several alterations in FGF signaling correlate with poor outcome in HCC patients, suggesting that this family of signaling molecules plays an important role in the development of HCC. Multikinase inhibitors targeting FGF signaling are currently under investigation in clinical trials. This review discusses the current understanding of the biological and clinical implications of aberrant FGF signaling in the prognosis, diagnosis, and treatment of HCC.

Fibroblast growth factor signaling regulates the expansion of A6-expressing hepatocytes in association with AKT-dependent β-catenin activation

BACKGROUND & AIMS

Fibroblast Growth Factors (FGFs) promote the proliferation and survival of hepatic progenitor cells (HPCs) via AKT-dependent β-catenin activation. Moreover, the emergence of hepatocytes expressing the HPC marker A6 during 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced liver injury is mediated partly by FGF and β-catenin signaling. Herein, we investigate the role of FGF signaling and AKT-mediated β-catenin activation in acute DDC liver injury.

METHODS

Transgenic mice were fed DDC chow for 14days concurrent with either Fgf10 over-expression or inhibition of FGF signaling via expression of soluble dominant-negative FGF Receptor (R)-2IIIb.

RESULTS

After 14days of DDC treatment, there was an increase in periportal cells expressing FGFR1, FGFR2, and AKT-activated phospho-Serine 552 (pSer552) β-Catenin in association with up-regulation of genes encoding the FGFR2IIIb ligands, Fgf7, Fgf10, and Fgf22. In response to Fgf10 over-expression, there was an increase in the number of pSer552-β-Catenin((positive)+ive) periportal cells as well as cells co-positive for A6 and hepatocyte marker, Hepatocyte Nuclear Factor-4α (HNF4α). A similar expansion of A6(+ive) cells was observed after Fgf10 over-expression with regular chow and after partial hepatectomy during ethanol toxicity. Inhibition of FGF signaling increased the periportal A6(+ive)HNF4α(+ive) cell population while reducing centrolobular A6(+ive) HNF4α(+ive) cells. AKT inhibition with Wortmannin attenuated FGF10-mediated A6(+ive)HNF4α(+ive) cell expansion. In vitro analyses using FGF10 treated HepG2 cells demonstrated AKT-mediated β-Catenin activation but not enhanced cell migration.

CONCLUSIONS

During acute DDC treatment, FGF signaling promotes the expansion of A6-expressing liver cells partly via AKT-dependent activation of β-Catenin expansion of A6(+ive) periportal cells and possibly by reprogramming of centrolobular hepatocytes.

FGF signalling through Fgfr2 isoform IIIb regulates adrenal cortex development

Developmental signalling pathways are implicated in the formation and maintenance of the adrenal gland, but their roles are currently not well defined. In recent years it has emerged that Sonic hedgehog (Shh) and Wnt/β catenin signalling are crucial for the growth and development of the adrenal cortex. Here we demonstrate that Fibroblast growth factor receptor (Fgfr) 2 isoforms IIIb and IIIc are expressed mainly in the adrenal subcapsule during embryogenesis and that specific deletion of the Fgfr2 IIIb isoform impairs adrenal development, causing reduced adrenal growth and impaired expression of SF1 and steroidogenic enzymes. The hypoplastic adrenals also have thicker, disorganised capsules which retain Gli1 expression but no longer express Dlk1. Fgfr2 ligands were detected in both the capsule and the cortex, suggesting the importance of signalling between the capsule and the cortex in adrenal development.

Intracellular Signaling Pathways in Rheumatoid Arthritis

Dysfunctional intracellular signaling involving deregulated activation of the Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT) and "cross-talk" between JAK/STAT and the stress-activated protein kinase/mitogen-activated protein kinase (SAPK/MAPK) and Phosphatidylinositide-3-Kinase/AKT/mammalian Target of Rapamycin (PI-3K/AKT/mTOR) pathways play a critical role in rheumatoid arthritis. This is exemplified by immune-mediated chronic inflammation, up-regulated matrix metalloproteinase gene expression, induction of articular chondrocyte apoptosis and "apoptosis-resistance" in rheumatoid synovial tissue. An important consideration in the development of novel therapeutics for rheumatoid arthritis will be the extent to which inhibiting these signal transduction pathways will sufficiently suppress immune cell-mediated inflammation to produce a lasting clinical remission and halt the progression of rheumatoid arthritis pathology. In that regard, the majority of the evidence accumulated over the past decade indicated that merely suppressing pro-inflammatory cytokine-mediated JAK/ STAT, SAPK/MAPK or PI-3K/AKT/mTOR activation in RA patients may be necessary but not sufficient to result in clinical improvement. Thus, targeting aberrant enzyme activities of spleen tyrosine kinase, sphingosine kinases-1, -2, transforming growth factor β-activated kinase-1, bone marrow kinase, and nuclear factor-κB-inducing kinase for intervention may also have to be considered.