Injury activated alveolar progenitors (IAAPs): the underdog of lung repair.

Alveolar epithelial type II cells (AT2s) together with AT1s constitute the epithelial lining of lung alveoli. In contrast to the large flat AT1s, AT2s are cuboidal and smaller. In addition to surfactant production, AT2s also serve as prime alveolar progenitors in homeostasis and play an important role during regeneration/repair. Based on different lineage tracing strategies in mice and single-cell transcriptomic analysis, recent reports highlight the heterogeneous nature of AT2s. These studies present compelling evidence for the presence of stable or transitory AT2 subpopulations with distinct marker expression, signaling pathway activation and functional properties. Despite demonstrated progenitor potentials of AT2s in maintaining homeostasis, through self-renewal and differentiation to AT1s, the exact identity, full progenitor potential and regulation of these progenitor cells, especially in the context of human diseases remain unclear. We recently identified a novel subset of AT2 progenitors named "Injury-Activated Alveolar Progenitors" (IAAPs), which express low levels of Sftpc, Sftpb, Sftpa1, Fgfr2b and Etv5, but are highly enriched for the expression of the surface receptor programmed cell death-ligand 1 (Pd-l1). IAAPs are quiescent during lung homeostasis but activated upon injury with the potential to proliferate and differentiate into AT2s. Significantly, a similar population of PD-L1 positive cells expressing intermediate levels of SFTPC are found to be expanded in human IPF lungs. We summarize here the current understanding of this newly discovered AT2 progenitor subpopulation and also try to reconcile the relationship between different AT2 stem cell subpopulations regarding their progenitor potential, regulation, and relevance to disease pathogenesis and therapeutic interventions.

Prediction of severe radiation-induced oral mucositis in locally advanced nasopharyngeal carcinoma using the combined systemic immune-inflammatory index and prognostic nutritional index.

OBJECTIVE: Severe radiation-induced oral mucositis (sRIOM) can seriously affect patients' quality of life and treatment compliance. This study was to investigate the utility of the systemic immune-inflammatory index (SII) and prognostic nutritional index (PNI) in predicting sRIOM in patients with locally advanced nasopharyngeal carcinoma (LANPC). METHODS: 295 patients with LANPC were retrospectively screened. The pre-radiotherapy SII and PNI were calculated based on peripheral blood samples. A receiver operating characteristic (ROC) curve was used to determine the cut-off value. Logistic regression was used for univariate and multivariate analyses. Patients were classified into three groups based on the SII-PNI score: score of 2, high SII (> cut-off value) and low PNI (≤ cut-off value); score of 1, either high SII or low PNI; score of 0, neither high SII nor low PNI. RESULTS: The SII-PNI demonstrated significant predictive ability for sRIOM occurrence, as evidenced by an area under the curve (AUC) of 0.738. The incidence rates of sRIOM with SII-PNI score of 2, 1, and 0 were 73.86%, 44.35%, and 18.07%, respectively. Multivariate analysis confirmed that the SII-PNI score was an independent risk factor for sRIOM. CONCLUSION: The SII-PNI score is a reliable and convenient indicator for predicting sRIOM in patients with LANPC.

Identification of a novel subset of alveolar type 2 cells enriched in PD-L1 and expanded following pneumonectomy.

Alveolar type 2 (AT2) cells are heterogeneous cells, with specialised AT2 subpopulations within this lineage exhibiting stem cell properties. However, the existence of quiescent, immature cells within the AT2 lineage that are activated during lung regeneration is unknown.SftpcCreERT2/+;tdTomatoflox/flox mice were used for the labelling of AT2 cells and labelled subpopulations were analysed by flow cytometry, quantitative PCR, assay for transposase-accessible chromatin using sequencing (ATAC-seq), gene arrays, pneumonectomy and culture of precision-cut lung slices. Single-cell RNA-sequencing (scRNA-seq) data from human lungs were analysed.In mice, we detected two distinct AT2 subpopulations, with low tdTomato level (TomLow) and high tdTomato level (TomHigh). TomLow cells express lower levels of the AT2 differentiation markers Fgfr2b and Etv5, while TomHigh, as bona fide mature AT2 cells, show higher levels of Sftpc, Sftpb, Sftpa1, Fgfr2b and Etv5 expression. ATAC-seq analysis indicates that TomLow and TomHigh cells constitute two distinct cell populations, with specific silencing of Sftpc, Rosa26 and cell cycle gene loci in the TomLow population. Upon pneumonectomy, the number of TomLow but not TomHigh cells increases and TomLow cells show upregulated expression of Fgfr2b, Etv5, Sftpc, Ccnd1 and Ccnd2 compared to Sham. TomLow cells overexpress programmed cell death 1 ligand 1 (PD-L1), an immune inhibitory membrane receptor ligand, which is used by flow cytometry to differentially isolate these two subpopulations. In the human lung, data mining of a recent scRNA-seq AT2 data set demonstrates the existence of a PD-L1 Pos population. Therefore, we have identified a novel population of AT2 quiescent, immature progenitor cells in mouse that expand upon pneumonectomy and we have provided evidence for the existence of such cells in human.

Lysosomal dynamics regulate mammalian cortical neurogenesis.

Mammalian neocortex formation follows a stereotypical pattern wherein the self-renew and differentiation of neural stem cells are coordinated with diverse organelle dynamics. However, the role of lysosomes in brain development has long been overlooked. Here, we demonstrate the highly dynamic lysosomal quantities, types, and localizations in developing brain. We observed asymmetric endolysosome inheritance during radial glial cell (RGC) division and the increased autolysosomes within intermediate progenitor cells (IPs) and newborn neurons. Disruption of lysosomal function shortens the S phase of the cell cycle and promotes RGC differentiation. Mechanistically, we revealed a post-transcriptional regulation governing ribosome homeostasis and cell-cycle progression through differential lysosomal activity modulation. In the human forebrain organoid, lysosomal dynamics are conserved; specifically, during the mitosis of outer subventricular zone RGCs (oRGs), lysosomes are inherited by the progeny without basal process. Together, our results identify the critical role of lysosomal dynamics in regulating mouse and human brain development.

Study on carotid artery stenosis after radiotherapy for nasopharyngeal carcinoma.

OBJECTIVE: This study investigated carotid artery stenosis (CAS) and associated risk factors in patients with nasopharyngeal carcinoma (NPC) post-radiotherapy. MATERIALS AND METHODS: The observation group comprised 86 reexamined patients with NPC, divided into Group 1 and Group 2 based on post-radiotherapy duration, alongside 34 newly diagnosed patients with NPC (Group 0). Carotid artery ultrasonography and chi-square analysis were performed. RESULTS: Moderate-to-severe vascular abnormalities were exclusively in Group 2. Considering mild vascular abnormalities as the standard, the overall vascular abnormality rates in Group 2 and Group 0 were 65.9% and 41.2%, respectively. In Group 2 and Group 0, the abnormality rates for unilateral carotid artery (UCA), common carotid artery (CCA), internal carotid artery (ICA), and external carotid artery (ECA) were 47.4% and 30.9%, 44.3% and 22.1%, 44.3% and 16.2%, and 39.8% and 5.9%, respectively. Comparing group 1 to group 0, only UCA abnormalities were statistically significant (45.4% vs. 30.9%). Considering moderate-to-severe vascular abnormalities as the standard, Group 2 had higher overall vascular, UCA, CCA, ICA, and ECA abnormality rates compared to Group 0. The age at revisit over 45 years, T stage, and N stage may influence CAS. CONCLUSION: Radiation increasing CAS incidence after 3 years. So, regular examinations are recommended to dynamically monitor CAS after 3 years of radiotherapy.

Effects of concurrent chemoradiotherapy with or without Endostar on the regression of retropharyngeal lymph node and prognosis of patients with locally advanced nasopharyngeal carcinoma: a retrospective study.

BACKGROUND AND PURPOSE: To investigate the effect of combining Endostar with concurrent chemoradiotherapy (ECCRT) compared to concurrent chemoradiotherapy (CCRT) on the regression rate of retropharyngeal lymph nodes (RLNs) and the relationship between regression rate of RLNs and prognosis of patients with locally advanced nasopharyngeal carcinoma (LANPC). METHODS: A total of 122 LANPC patients with RLNs metastasis were included. Metastatic RLNs were delineated both before and after treatment slice by slice on the magnetic resonance images cross-section. The regression rate of RLNs, adverse effects (AE) were evaluated. The median regression rate of RLNs was taken as the cut-off value, and the patients were furtherly divided into high regression rate (HRR) group and low regression rate (LRR) group, then survival times were evaluated. RESULTS: The median regression rates of RLNs in the ECCRT and CCRT groups were 81% and 50%, respectively (P < 0.001). There was no statistically significant difference in the incidence of grade 3/4 AEs between the two groups, except for oral mucositis (ECCRT 26.23% vs. CCRT 44.26%, P = 0.037). The 3-year overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS) and locoregional failure-free survival (LRFFS) rates in the HRR and LRR groups were 85.48% and 86.67% (P = 0.983), 80.65% and 68.33% (P = 0.037), 83.87% and 85% (P = 0.704), 93.55% and 81.67% (P = 0.033), respectively. CONCLUSIONS: Patients in the ECCRT group had higher regression rates of RLNs and lower incidence of severe oral mucositis. Furthermore, patients in the HRR group had a better 3-year PFS and LRFFS rate than those in the LRR group.

Diet was less significant than physical activity in the prognosis of people with sarcopenia and metabolic dysfunction-associated fatty liver diseases: Analysis of the National Health and Nutrition Examination Survey III.

Background: Sarcopenia is prevalent in metabolic dysfunction-associated fatty liver diseases (MAFLD), and the primary treatment for both diseases is lifestyle modification. We studied how dietary components and physical activity affect individuals with sarcopenia and MAFLD. Materials and methods: We conducted a study utilizing National Health and Nutrition Examination Survey (NHANES) III (1988-1994) data with Linked Mortality file (through 2019). The diagnosis of fatty liver disease (FLD) was based on ultrasound images revealing moderate and severe steatosis. Using bioelectrical measures, sarcopenia was assessed. Using self-report data, dietary intake and physical activity levels were evaluated. Results: Among 12,259 participants, 2,473 presented with MAFLD, and 290 of whom had sarcopenia. Higher levels of physical activity (odds ratio [OR] = 0.51 [0.36-0.95]) and calorie (OR = 0.58 [0.41-0.83]) intake reduced the likelihood of sarcopenia in MAFLD patients. During a median follow-up period of 15.3 years, 1,164 MAFLD and 181 MAFLD patients with sarcopenia perished. Increased activity levels improved the prognosis of patients with sarcopenia (Insufficiently active, HR = 0.75 [0.58-0.97]; Active, HR = 0.64 [0.48-0.86]), which was particularly pronounced in older patients. Conclusion: In the general population, hyperglycemia was highly related to MAFLD prognosis. Physical inactivity and a protein-restricted diet corresponded to sarcopenia, with physical inactivity being connected to poor outcomes. Adding protein supplements would be beneficial for older people with sarcopenia who are unable to exercise due to frailty, while the survival benefits were negligible.

A nomogram model for predicting distant metastasis of newly diagnosed colorectal cancer based on clinical features.

Objective: Colorectal cancer is one of the most common primary malignancies and the third most common cause of cancer death in both men and women in the United States. Among people diagnosed with initial colorectal cancer, 22% had metastatic colorectal cancer, while the 5-year survival rate was less than 20%. The purpose of this study is to develop a nomogram for predicting distant metastasis in newly diagnosed colorectal cancer patients and to identify high-risk groups. Methods: We retrospectively reviewed the data of patients who were diagnosed with colorectal cancer at Zhong nan Hospital of Wuhan University and People's Hospital of Gansu Province between January 2016 and December 2021. Risk predictors for distant metastasis from colorectal patients were determined by the univariate and multivariate logistic regression analyses. Nomograms were developed to predict the probabilities of distant metastatic sites of colorectal cancer patients and evaluated by calibration curves, receiver operating characteristic curves, and decision curve analysis (DCA). Results: A total of 327 cases were included in this study: 224 colorectal cancer patients from Zhong nan Hospital of Wuhan University were incorporated into the training set, and 103 colorectal cancer patients from Gansu Provincial People's Hospital were incorporated into the testing set. By univariate logistic regression analysis, platelet (PLT) level (p = 0.009), carcinoembryonic antigen (CEA) level (p = 0.032), histological grade (p < 0.001), colorectal cancer tumor markers (p < 0.001), N stage (p < 0.001), and tumor site (p = 0.005) were associated with distant metastasis in colorectal cancer patients. Multivariate logistic regression analysis showed that N stage (p < 0.001), histological grade (p = 0.026), and colorectal cancer markers (p < 0.001) were independent predictors of distant metastasis in patients initially diagnosed with colorectal cancer. The above six risk factors were used to predict distant metastasis of newly diagnosed colorectal cancer. The C-indexes for the prediction of the nomogram were 0.902 (95% confidence interval (CI), 0.857-0.948). Conclusion: The nomogram showed excellent accuracy in predicting distant metastatic sites, and clinical utility may facilitate clinical decision-making.

Seizures and Consciousness Disorder Secondary to Intracranial Hypotension After Spinal Surgery: A Case Report and Literature Review.

Rationale: Cerebrospinal fluid (CSF) leakage is a common condition after spinal surgery and is also the most common cause of intracranial hypotension. Intracranial hypotension (IH) is typically characterized by an orthostatic headache with associated nausea, vomiting, tinnitus, vertigo, hypoacusis, neck stiffness, and photophobia. There have been limited case reports describing surgery-associated IH presenting with seizures and disorder of consciousness. Due to the atypia of symptoms, these clinical manifestations are usually ignored or even misdiagnosed. As a result, clinicians face a significant challenge in detecting IH early and understanding its various clinical presentations. Meanwhile, we summarize the cases of IH presenting as seizures in recent years, including its clinical characteristics and effective treatment, which will be very helpful for the early diagnosis of IH. Patient concerns: A 72-year-old Chinese male patient developed status epilepticus, a disorder of consciousness, and quadriplegia when he finished spinal surgery, although he had no previous seizures or any seizure risk factors. Diagnosis: After MRI and CT examination, subdural hygromas were found under both sides of the skull, and combined with the clinical manifestations of the patient, intracranial hypotension due to cerebrospinal fluid leakage was diagnosed. Interventions: In the early stage, we carried out strict perioperative critical care for the patient. Trendelenburg position was conducted to relieve intracranial hypotension. The dural repair surgery was performed after the diagnosis of CSF leakage. Outcomes: Seizures in the patient were resolved. Three months after discharge, he was gradually returning to normal life. Lessons: One possible cause of unexplained seizures and disorder of consciousness after spinal surgery is cerebrospinal fluid leakage associated with intracranial hypotension syndrome. Trendelenburg position and dural repair surgery are effective ways to relieve intracranial hypotension and associated symptoms. Better awareness of the association between IH (intracranial hypotension) and seizures may help us improve early recognition of the syndrome.

Cytomegalovirus Proctitis Developed after COVID-19 Vaccine: A Case Report and Literature Review.

(1) Background: We describe a case of a 58-year-old Chinese woman, without obvious cause of immunosuppression, who developed cytomegalovirus (CMV) proctitis three days after a second COVID-19 vaccination. Electronic colonoscopy revealed a new lesion that was circumferential at the anorectal junction, with an uneven surface and ulceration, which mimicked rectal carcinoma. This is the first case of CMV proctitis following vaccination since the invention of the COVID-19 vaccine, suggesting that the COVID-19 vaccine may cause disorders of immune homeostasis, including not only immune hyperactivity but also immune deficiency. We report this case to increase readers' awareness of the risks after COVID-19 vaccination and to provide new ideas for the diagnosis and treatment of similar cases. (2) Methods: In this case, we used laboratory biochemical examinations, colonoscopy, immunohistochemistry, and a biochemical index to confirm the existence of CMV proctitis. (3) Results: In this case, the vaccine-induced CMV proctitis had a similar endoscopic appearance to rectal neoplastic lesions, which could be confirmed by biopsy and quickly relieved by ganciclovir treatment. Ganciclovir was used to treat the patient, and a good effect was observed. (4) Conclusions: COVID-19 vaccination may cause immune disorders, not just immune hyperactivity as previously reported, but also immune deficiency, such as CMV proctitis in this case. The clinical course of CMV proctitis secondary to COVID-19 vaccination was favorable with ganciclovir therapy.

FGF10 Therapeutic Administration Promotes Mobilization of Injury-Activated Alveolar Progenitors in a Mouse Fibrosis Model.

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease with dire consequences and in urgent need of improved therapies. Compelling evidence indicates that damage or dysfunction of AT2s is of central importance in the development of IPF. We recently identified a novel AT2 subpopulation characterized by low SFTPC expression but that is enriched for PD-L1 in mice. These cells represent quiescent, immature AT2 cells during normal homeostasis and expand upon pneumonectomy (PNX) and were consequently named injury-activated alveolar progenitors (IAAPs). FGF10 is shown to play critical roles in lung development, homeostasis, and injury repair demonstrated in genetically engineered mice. In an effort to bridge the gap between the promising properties of endogenous Fgf10 manipulation and therapeutic reality, we here investigated whether the administration of exogenous recombinant FGF10 protein (rFGF10) can provide preventive and/or therapeutic benefit in a mouse model of bleomycin-induced pulmonary fibrosis with a focus on its impact on IAAP dynamics. C57BL/6 mice and SftpcCreERT2/+; tdTomatoflox/+ mice aged 8-10 weeks old were used in this study. To induce the bleomycin (BLM) model, mice were intratracheally (i.t.) instilled with BLM (2 µg/g body weight). BLM injury was induced after a 7-day washout period following tamoxifen induction. A single i.t. injection of rFGF10 (0.05 µg/g body weight) was given on days 0, 7, 14, and 21 after BLM injury. Then, the effects of rFGF10 on BLM-induced fibrosis in lung tissues were assessed by H&E, IHC, Masson's trichrome staining, hydroxyproline and Western blot assays. Immunofluorescence staining and flow cytometry was used to assess the dynamic behavior of AT2 lineage-labeled SftpcPos (IAAPs and mature AT2) during the course of pulmonary fibrosis. We observed that, depending on the timing of administration, rFGF10 exhibited robust preventive or therapeutic efficacy toward BLM-induced fibrosis based on the evaluation of various pathological parameters. Flow cytometric analysis revealed a dynamic expansion of IAAPs for up to 4 weeks following BLM injury while the number of mature AT2s was drastically reduced. Significantly, rFGF10 administration increased both the peak ratio and the duration of IAAPs expansion relative to EpCAMPos cells. Altogether, our results suggest that the administration of rFGF10 exhibits therapeutic potential for IPF most likely by promoting IAAP proliferation and alveolar repair.

FGF10 and Lipofibroblasts in Lung Homeostasis and Disease: Insights Gained From the Adipocytes.

Adipocytes not only function as energy depots but also secrete numerous adipokines that regulate multiple metabolic processes, including lipid homeostasis. Dysregulation of lipid homeostasis, which often leads to adipocyte hypertrophy and/or ectopic lipid deposition in non-adipocyte cells such as muscle and liver, is linked to the development of insulin resistance. Similarly, an altered secretion profile of adipokines or imbalance between calorie intake and energy expenditure is associated with obesity, among other related metabolic disorders. In lungs, lipid-laden adipocyte-like cells known as lipofibroblasts share numerous developmental and functional similarities with adipocytes, and similarly influence alveolar lipid homeostasis by facilitating pulmonary surfactant production. Unsurprisingly, disruption in alveolar lipid homeostasis may propagate several chronic inflammatory disorders of the lung. Given the numerous similarities between the two cell types, dissecting the molecular mechanisms underlying adipocyte development and function will offer valuable insights that may be applied to, at least, some aspects of lipofibroblast biology in normal and diseased lungs. FGF10, a major ligand for FGFR2b, is a multifunctional growth factor that is indispensable for several biological processes, including development of various organs and tissues such as the lung and WAT. Moreover, accumulating evidence strongly implicates FGF10 in several key aspects of adipogenesis as well as lipofibroblast formation and maintenance, and as a potential player in adipocyte metabolism. This review summarizes our current understanding of the role of FGF10 in adipocytes, while attempting to derive insights on the existing literature and extrapolate the knowledge to pulmonary lipofibroblasts.

Changes in physicochemical profiles and quality of apple juice treated by ultrafiltration and during its storage.

Effects of various factors, such as membrane materials, molecular weight cutoff, transmembrane pressure (TMP), and cross flow rate (CFR) on flux and physicochemical properties of apple juice during ultrafiltration and storage have been investigated. Clarity, color, total phenols, total proteins, total sugars, total soluble solids (TSS), pH, and some specific polyphenols of juices were evaluated. Results show that at conditions of PES-10 kDa, CFR 30 L/hr, and TMP 0.75 MPa, a clarified juice obtained with color 0.15 A, clarity 96.94%T, TSS 9.55 °Brix, pH 4.2, and total phenols, total proteins, and total sugars were 64.12 and 13.20 µg/ml and 50.70 mg/ml, respectively. Chlorogenic acid, epicatechin, phloridzin, catechin, and caffeic acid decreased differently from 32.63, 17.33, 3.25, 7.58, and 0.75 µg/ml to 17.24, 12.38, 1.79, 5.27, and 0.25 µg/ml, respectively. Storage in refrigeration for 4 weeks, clarity, total sugars, and total phenols reduced by 2.5%, 6.4%, and 16.6%, respectively, while TSS increased by 3.1%.

Loss of Rsph9 causes neonatal hydrocephalus with abnormal development of motile cilia in mice.

Hydrocephalus is a brain disorder triggered by cerebrospinal fluid accumulation in brain cavities. Even though cerebrospinal fluid flow is known to be driven by the orchestrated beating of the bundled motile cilia of ependymal cells, little is known about the mechanism of ciliary motility. RSPH9 is increasingly becoming recognized as a vital component of radial spokes in ciliary "9 + 2" ultrastructure organization. Here, we show that deletion of the Rsph9 gene leads to the development of hydrocephalus in the early postnatal period. However, the neurodevelopment and astrocyte development are normal in embryonic Rsph9-/- mice. The tubular structure of the central aqueduct was comparable in Rsph9-/- mice. Using high-speed video microscopy, we visualized lower beating amplitude and irregular rotation beating pattern of cilia bundles in Rsph9-/- mice compared with that of wild-type mice. And the centriolar patch size was significantly increased in Rsph9-/- cells. TEM results showed that deletion of Rsph9 causes little impact in ciliary axonemal organization but the Rsph9-/- cilia frequently had abnormal ectopic ciliary membrane inclusions. In addition, hydrocephalus in Rsph9-/- mice results in the development of astrogliosis, microgliosis and cerebrovascular abnormalities. Eventually, the ependymal cells sloughed off of the lateral wall. Our results collectively suggested that RSPH9 is essential for ciliary structure and motility of mouse ependymal cilia, and its deletion causes the pathogenesis of hydrocephalus.

Histone Variants and Histone Modifications in Neurogenesis.

During embryonic brain development, neurogenesis requires the orchestration of gene expression to regulate neural stem cell (NSC) fate specification. Epigenetic regulation with specific emphasis on the modes of histone variants and histone post-translational modifications are involved in interactive gene regulation of central nervous system (CNS) development. Here, we provide a broad overview of the regulatory system of histone variants and histone modifications that have been linked to neurogenesis and diseases. We also review the crosstalk between different histone modifications and discuss how the 3D genome affects cell fate dynamics during brain development. Understanding the mechanisms of epigenetic regulation in neurogenesis has shifted the paradigm from single gene regulation to synergistic interactions to ensure healthy embryonic neurogenesis.

Erratum: The WW domains dictate isoform-specific regulation of YAP1 stability and pancreatic cancer cell malignancy: Erratum.

[This corrects the article DOI: 10.7150/thno.42795.].

Corrigendum: An FGFR/AKT/SOX2 Signaling Axis Controls Pancreatic Cancer Stemness.

[This corrects the article DOI: 10.3389/fcell.2020.00287.].

The WW domains dictate isoform-specific regulation of YAP1 stability and pancreatic cancer cell malignancy.

YAP1 is a key mediator of the Hippo pathway capable of exerting a profound effect on organ size as well as tumorigenesis. Alternative mRNA splicing of human YAP1 results in at least 8 protein isoforms that differ within the 2nd WW motif and the transcriptional activation domain. Methods: To investigate the isoform-specific differences in their mRNA expression, transcriptional activity and tumor-promoting function, we cloned cDNA encoding all of the eight YAP1 protein isoforms. Then, we examined their mRNA expression, subcellular localization, transcriptional regulation properties, interactions with key regulatory partners, and protein stability in response to changes in cell density, as well as their effects on pancreatic cancer cell malignancy both in vitro and in vivo. Results: Multiple YAP1 mRNA isoforms are expressed in commonly used pancreatic cancer lines as well as human pancreatic cancer PDX lines. Based on the analysis of heterologous reporter and endogenous target genes, all YAP1 isoforms are capable of activating transcription, albeit to a different extent. Importantly, we unveiled a marked discrepancy between the mRNA and protein expression levels of the YAP1-1 and YAP1-2 isoforms. We further discovered that the YAP1-2 isoform, which contains two tandem WW motifs, is less stable at the protein level, particularly at high cell densities. Mechanistically, we found that the presence of the 2nd WW motif in YAP1-2 facilitates the de novo formation of the YAP1-2/AMOT/LATS1 complex and contributes to a stronger binding of YAP1-2 to LATS1 and subsequently increased YAP1-2 ubiquitination and degradation by ß-TRCP. Conclusion: Our data reveals a potent effect of YAP1-1 on pancreatic cancer malignancy in vitro and in vivo and provides novel mechanistic insight into isoform-specific and cell density-dependent regulation of YAP1 stability, as well as its impact on cancer malignancy.

An FGFR/AKT/SOX2 Signaling Axis Controls Pancreatic Cancer Stemness.

Cancer stemness is associated with high malignancy and low differentiation, as well as therapeutic resistance of tumors including pancreatic ductal adenocarcinoma (PDAC). Fibroblast growth factors (FGFs) exert pleiotropic effects on a variety of cellular processes and functions including embryonic stem cell pluripotency and cancer cell stemness via the activation of four tyrosine kinase FGF receptors (FGFRs). FGF ligands have been a major component of the cocktail of growth factors contained in the cancer stemness-inducing (CSI) and organoid culture medium. Although FGF/FGFR signaling has been hypothesized to maintain cancer stemness, its function in this process is still unclear. We report that inhibition of FGF/FGFR signaling impairs sphere-forming ability of PDAC in vitro, and knocking down FGFR1 and FGFR2 decreased their tumorigenesis abilities in vivo. Mechanistically, we demonstrated that SOX2 is down-regulated upon loss of FGFR signaling. The overexpression of SOX2 in SOX2-negative cells, which normally do not display stemness capabilities, is sufficient to induce spheroid formation. Additionally, we found that AKT phosphorylation was reduced upon FGFR signaling inhibition. The inhibition of AKT using specific pharmacological inhibitors in the context of CSI medium leads to the loss of spheroid formation associated with loss of SOX2 nuclear expression and increased degradation. We demonstrate that an FGFR/AKT/SOX2 axis controls cancer stemness in PDAC and therefore may represent an important therapeutic target in the fight against this very aggressive form of cancer.

Role of FGF10/FGFR2b Signaling in Mouse Digestive Tract Development, Repair and Regeneration Following Injury.

During embryonic development, the rudimentary digestive tract is initially a tube-like structure. It is composed of epithelial cells surrounded by mesenchymal cells. Reciprocal epithelial-mesenchymal interactions progressively subdivide this primitive tube into distinct functional regions: the tongue, the pharynx, the esophagus, the stomach, the duodenum, the small intestine, the cecum, the large intestine, the colon, and the anus as well as the pancreas and the liver. Fibroblast growth factors (Fgfs) constitute a family of conserved small proteins playing crucial roles during organogenesis, homeostasis, and repair after injury. Among them, fibroblast growth factor 10 (Fgf10) has been reported to orchestrate epithelial-mesenchymal interactions during digestive tract development. In mice, loss of function of Fgf10 as well as its receptor fibroblast growth factor receptor 2b (Fgfr2b) lead to defective taste papillae in the tongue, underdeveloped and defective differentiation of the stomach, duodenal, cecal, and colonic atresias, anorectal malformation, as well as underdeveloped pancreas and liver. Fgf signaling through Fgfr2b receptor is also critical for the repair process after gut injury. In the adult mice, a malabsorption disorder called small bowel syndrome is triggered after massive small bowel resection (SBR). In wild-type mice, SBR leads to a regenerative process called gut adaptation characterized by an increase in the diameter of the remaining small intestine as well as by the presence of deeper crypts and longer villi, altogether leading to increased intestinal surface. Intestinal stem cells are key for this regeneration process. Induction of Fgf10 expression in the Paneth cells located in the crypt following SBR suggests a critical role for this growth factor in the process of gut adaptation.