YAP1 controls the N-cadherin-mediated tumor-stroma interaction in melanoma progression.

The hallmark of epithelial-to-mesenchymal transition (EMT) is the switch from epithelial cadherin (E-cadherin) to neural cadherin (N-cadherin), allowing melanoma cells to form a homotypic N-cadherin-mediated adhesion with stromal fibroblasts. However, how cadherin switching is initiated, maintained, and regulated in melanoma remains elusive. Here, we report a novel mechanism underlying cadherin switching in melanoma cells that is regulated by stromal Yes-associated protein 1 (YAP1) signaling. The progression of a BRAF-mutant mouse melanoma was suppressed in vivo upon YAP1 ablation in cancer-associated fibroblasts (CAFs). On the contrary, overexpressing YAP1 in CAFs accelerated melanoma development. By RNA-Seq, N-cadherin was identified as a major downstream effector of YAP1 signaling in CAFs. YAP1 silencing reduced N-cadherin expression in CAFs, leading to the downregulation of N-cadherin in neighboring melanoma cells. N-cadherin ablation inhibited the PI3K-AKT signaling pathway in melanoma cells and melanoma cell proliferation. The findings suggest that YAP1 depletion in CAFs induces the downregulation of p-AKT signaling in melanoma cells through the N-cadherin-mediated interaction between melanoma cells and CAFs. The data underscore an important role of CAFs in regulating N-cadherin-mediated adhesion and signaling in melanoma and highlight that disentangling cadherin-mediated cell-cell interactions can potentially disrupt tumor-stroma interactions and reverse the tumor cell invasive phenotype.

Teriflunomide Promotes Blood-Brain Barrier Integrity by Upregulating Claudin-1 via the Wnt/ß-catenin Signaling Pathway in Multiple Sclerosis.

The blood-brain barrier (BBB) and tight junction (TJ) proteins maintain the homeostasis of the central nervous system (CNS). The dysfunction of BBB allows peripheral T cells infiltration into CNS and contributes to the pathophysiology of multiple sclerosis (MS). Teriflunomide is an approved drug for the treatment of MS by suppressing lymphocytes proliferation. However, whether teriflunomide has a protective effect on BBB in MS is not understood. We found that teriflunomide restored the injured BBB in the EAE model. Furthermore, teriflunomide treatment over 6 months improved BBB permeability and reduced peripheral leakage of CNS proteins in MS patients. Teriflunomide increased human brain microvascular endothelial cell (HBMEC) viability and promoted BBB integrity in an in vitro cell model. The TJ protein claudin-1 was upregulated by teriflunomide and responsible for the protective effect on BBB. Furthermore, RNA sequencing revealed that the Wnt signaling pathway was affected by teriflunomide. The activation of Wnt signaling pathway increased claudin-1 expression and reduced BBB damage in cell model and EAE rats. Our study demonstrated that teriflunomide upregulated the expression of the tight junction protein claudin-1 in endothelial cells and promoted the integrity of BBB through Wnt signaling pathway.

The repeatability and consistency of different methods for measuring the volume parameters of the primary rectal cancer on diffusion weighted images.

Background: To determine the reproducibility of measuring the gross total volume (GTV) of primary rectal tumor with manual and semi-automatic delineation on the diffusion-weighted image (DWI), examine the consistency of using the same delineation method on DWI images with different high b-values, and find the optimal delineation method to measure the GTV of rectal cancer. Methods: 41 patients who completed rectal MR examinations in our hospital from January 2020 to June 2020 were prospectively enrolled in this study. The post-operative pathology confirmed the lesions were rectal adenocarcinoma. The patients included 28 males and 13 females, with an average age of (63.3 ± 10.6) years old. Two radiologists used LIFEx software to manually delineate the lesion layer by layer on the DWI images (b=1000 s/mm2 and 1500 s/mm2) and used 10% to 90% of the highest signal intensity as thresholds to semi-automatically delineate the lesion and measure the GTV. After one month, Radiologist 1 performed the same delineation work again to obtain the corresponding GTV. Results: The inter- and intra-observer interclass correlation coefficients (ICC) of measuring GTV using semi-automatic delineation with 30% to 90% as thresholds were all >0.900. There was a positive correlation between manual delineation and semi-automatic delineation with 10% to 50% thresholds (P < 0.05). However, the manual delineation was not correlated with the semi-automatic delineation with 60%, 70%, 80%, and 90% thresholds. On the DWI images with b=1000 s/mm2 and 1500 s/mm2, the 95% limit of agreement (LOA%) of measuring GTV using semi-automatic delineation with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% thresholds were -41.2~67.4, -17.8~51.5, -16.1~49.3, -26.2~50.1, -42.3~57.6, -57.1~65.4, -67.3~66.5, -101.6~91.1, -129.4~136.0, and -15.3~33.0, respectively. The time required for GTV measurement by semi-automatic delineation was significantly shorter than that of manual delineation (12.9 ± 3.6s vs 40.2 ± 13.1s). Conclusions: The semi-automatic delineation of rectal cancer GTV with 30% threshold had high repeatability and consistency, and it was positively correlated with the GTV measured by manual delineation. Therefore, the semi-automatic delineation with 30% threshold could be a simple and feasible method for measuring rectal cancer GTV.

An improved human skin explant culture method for testing and assessing personal care products.

BACKGROUND: Cultured human skin models have been widely used in the evaluation of dermato-cosmetic products as alternatives to animal testing and expensive clinical testing. The most common in vitro skin culture approach is to maintain skin biopsies in an airlifted condition at the interface of the supporting culture medium and the air phase. This type of ex vivo skin explant culture is not, however, adequate for the testing of cleansing products, such as shampoos and body washes. One major deficiency is that cleansing products would not remain confined on top of the epidermis and have a high chance of running off toward the dermal side, thus compromising the experimental procedure and data interpretation. MATERIALS AND METHODS: Here, we describe an improved ex vivo method for culturing full-thickness human skin for the effective testing and evaluation of skin care products by topical application. RESULTS: This newly developed ex vivo human skin culture method has the ability to maintain healthy skin tissues for up to 14 days in culture. Importantly, the model provides a quick and safe way to evaluate skin care products at different time points after single or repetitive topical applications using a combined regimen of leave-on and wash-off. We found that the results obtained using the new skin culture method are reproducible and consistent with the data collected from clinical testing. CONCLUSION: Our new ex vivo skin explant method offers a highly efficient and cost-effective system for the evaluation and testing of a variety of personal care products and new formulations.

The dermal papilla dilemma and potential breakthroughs in bioengineering hair follicles.

The generation and growing of de novo hair follicles is the most daring hair replacement approach to treat alopecia. This approach has been explored at least since the 1960s without major success. Latest in the 1980s, the realization that the mesenchymal compartment of hair follicles, the dermal papilla (DP), is the crucial signaling center and element required for fulfilling this vision of hair follicle engineering, propelled research into the fibroblasts that occupy the DP. However, working with DP fibroblasts has been stubbornly frustrating. Decades of work in understanding the nature of DP fibroblasts in vitro and in vivo have led to the appreciation that hair follicle biology is complex, and the dermal papilla is an enigma. Functional DP fibroblasts tend to aggregate in 2D culture, while impaired DP cells do not. This fact has stimulated recent approaches to overcome the hurdles to DP cell culture by mimicking their natural habitat, such as growing DP fibroblasts in three dimensions (3D) by their self-aggregation, adopting 3D matrix scaffold, or bioprinting 3D microstructures. Furthermore, including keratinocytes in the mix to form hair follicle-like composite structures has been explored but remains a far cry from a useful and affordable method to generate human hair follicles in sufficient quantity and quality in a practical time frame for patients. This suggests that the current strategies may have reached their limitations in achieving successful hair follicle bioengineering for clinical applications. Novel approaches are required to overcome these barriers, such as focusing on embryonic cell types and processes in combination with emerging techniques.

High-resolution silkworm pan-genome provides genetic insights into artificial selection and ecological adaptation.

The silkworm Bombyx mori is an important economic insect for producing silk, the "queen of fabrics". The currently available genomes limit the understanding of its genetic diversity and the discovery of valuable alleles for breeding. Here, we deeply re-sequence 1,078 silkworms and assemble long-read genomes for 545 representatives. We construct a high-resolution pan-genome dataset representing almost the entire genomic content in the silkworm. We find that the silkworm population harbors a high density of genomic variants and identify 7308 new genes, 4260 (22%) core genes, and 3,432,266 non-redundant structure variations (SVs). We reveal hundreds of genes and SVs that may contribute to the artificial selection (domestication and breeding) of silkworm. Further, we focus on four genes responsible, respectively, for two economic (silk yield and silk fineness) and two ecologically adaptive traits (egg diapause and aposematic coloration). Taken together, our population-scale genomic resources will promote functional genomics studies and breeding improvement for silkworm.

Effect of human follicle-stimulating hormone on immunomodulatory function of decidual mesenchymal stem cells by reducing interleukin-6 levels.

OBJECTIVE: Women with an elevated basal FSH indicate diminished ovarian reserve and reduced oocyte and embryo numbers. DMSCs are likely to be involved in immune tolerance of pregnancy maintenance. We investigate the effect of follicle-stimulating hormones on the immunomodulatory functions of DMSCs. METHODS: DMSCs were primary cultured from decidual tissue. Pretreated DMSCs with mitomycin C, combined with CD4+ T lymphocytes, DMSCs + CD4+T co-culture system was established. Different physiological dose FSH (3 ng/ml,10 ng/ml,30 ng/ml,100 ng/ml) were used to co-culture system. Cytokines (IFN-γ, IL-2, IL-4, IL-6, IL-10, TNF-α) and other proteins (FSHR, MyD88) were measured. RESULTS: Compared with the control group (FSH (0 ng/mL) + CD4+T + DMSCs), the FSH concentration was 10, 30, and 100 ng/ml, IL-6 levels were significantly reduced (P < 0.05). IL-6, MyD88 protein expression was remarkably decreased (P < 0.05). CONCLUSION: FSH/FSHR could negatively regulate the immunosuppressive function of DMSCs by reducing secretion of IL-6 levels through MyD88 pathways, but upstream and downstream signalling pathways require further validation.

BRAF Inhibitors Reprogram Cancer-Associated Fibroblasts to Drive Matrix Remodeling and Therapeutic Escape in Melanoma.

The tumor stroma and its cellular components are known to play an important role in tumor response to treatment. Here, we report a novel resistance mechanism in melanoma that is elicited by BRAF inhibitor (BRAFi)-induced noncanonical activation of nuclear ß-catenin signaling in cancer-associated fibroblasts (CAF). Treatment with BRAFi leads to an expanded CAF population with increased ß-catenin nuclear accumulation and enhanced biological properties. This CAF subpopulation is essential for melanoma cells to proliferate and acquire resistance to BRAFi/MEK inhibitors (MEKi). Mechanistically, BRAFi induces BRAF-CRAF heterodimerization and subsequent activation of ERK signaling in CAFs, leading to inactivation of the ß-catenin destruction complex. RNA-seq identified periostin (POSTN) as a major downstream effector of ß-catenin in CAFs. POSTN compensates for the loss of ß-catenin in CAFs and mediates melanoma cell BRAFi/MEKi resistance. In melanoma cells, POSTN activates phosphoinositide 3-kinase (PI3K)/AKT signaling and subsequently reactivates the ERK pathway that was inhibited by BRAFi/MEKi. Collectively, these data underscore the role of BRAFi-induced CAF reprogramming in matrix remodeling and therapeutic escape of melanoma cells. SIGNIFICANCE: ß-Catenin activation in cancer-associated fibroblasts in response to BRAF inhibitors stimulates POSTN secretion to promote resistance in cancer cells, revealing POSTN as a potential matrix target in cancer therapy.

A Comprehensive Nomogram Combining CT Imaging with Clinical Features for Prediction of Lymph Node Metastasis in Stage I-IIIB Non-small Cell Lung Cancer.

OBJECTIVE: The status of lymph node metastasis (LNM) is highly correlated with the recurrence and survival outcomes of patients with lung cancer. Thus, a tool that predicts LNM could benefit patient treatment and prognosis. The present study established a new radiomic model by combining computed tomography (CT) radiomic features and clinical parameters to predict the LNM status in patients with non-small cell lung cancer (NSCLC). METHODS: Demographic parameters and clinical laboratory values were analyzed in 217 patients with stage I-IIIB NSCLC; 107 of the patients received CT scanning and radiomic characteristics were used for LNM assessment (76 in the training cohort and 31 in the validation cohort). The minimum redundancy maximum relevance (mRMR) and the least absolute shrinkage and selection operator (LASSO) regression model were used to select the most predictive features on the basis of the 76 patients in the training set. The value of the area under the receiver operator characteristic (ROC) curve (AUC) was adopted to determine the correlation between LN status and the radiomics signature in training cohorts and then validated in the 31 patients of validation set. The radiomics nomogram was analyzed using univariate and multivariate logistic regression. Decision curve analysis (DCA) was performed to evaluate the clinical utility of this model. RESULTS: This was a retrospective study. Five radiomic characteristics were significantly correlated with LNM in the two cohorts (P < 0.05). The radiomic nomogram that incorporated the above radiomic characteristics, the RDW, and the CT-based LN status had satisfactory discrimination and calibration in the training (AUC, 0.79; 95% CI 0.69-0.89) and validation cohorts (AUC, 0.70; 95% CI 0.50-0.89).The DCA showed that the developed nomogram had promising clinical utility. CONCLUSIONS: The developed nomogram, combined with preoperative radiomics evidence, the RDW, and the CT-based LN status, has the potential to preoperatively predict LNM with high accuracy and can facilitate the prediction of LN status for NSCLC patients.

GSS-RiskAsser: A Multi-Modal Deep-Learning Framework for Urban Gas Supply System Risk Assessment on Business Users.

Gas supply system risk assessment is a serious and important problem in cities. Existing methods tend to manually build mathematical models to predict risk value from single-modal information, i.e., pipeline parameters. In this paper, we attempt to consider this problem from a deep-learning perspective and define a novel task, Urban Gas Supply System Risk Assessment (GSS-RA). To drive deep-learning techniques into this task, we collect and build a domain-specific dataset GSS-20K containing multi-modal data. Accompanying the dataset, we design a new deep-learning framework named GSS-RiskAsser to learn risk prediction. In our method, we design a parallel-transformers Vision Embedding Transformer (VET) and Score Matrix Transformer (SMT) to process multi-modal information, and then propose a Multi-Modal Fusion (MMF) module to fuse the features with a cross-attention mechanism. Experiments show that GSS-RiskAsser could work well on GSS-RA task and facilitate practical applications. Our data and code will be made publicly available.

Attenuation model of tunnel blast vibration velocity based on the influence of free surface.

In tunnel blasting excavation, it is important to clarify the attenuation law of blast wave propagation and predict the blast vibration velocity effectively to ensure safe tunnel construction and protection design. The effects of the free surface area its quantity on the blast vibration velocity are considered, and free surface parameters are introduced to improve the existing blast vibration velocity prediction formula. Based on the Tianhuan railway Daqianshiling tunnel project, field blast vibration monitoring tests are performed to determine changes in the peak blasting vibration velocity based on the blast distance and free surface area. LS-DYNA is used to establish tunnel blasting excavation models under three operating conditions; subsequently, the attenuation law of blast vibration velocity and changes in the vibration response spectrum are analysed. Results show that the free surface area and number of free surfaces enable the blast vibration velocity to be predicted under various operating conditions: a smaller free surface area results in a narrower frequency band range, whereas more free surfaces result in a narrower frequency band range. The improved blast vibration velocity prediction formula is validated using field and numerical test data. It is indicated that the improved formula is applicable to various tunnelling conditions.

Bub1 and CENP-U redundantly recruit Plk1 to stabilize kinetochore-microtubule attachments and ensure accurate chromosome segregation.

Bub1 is required for the kinetochore/centromere localization of two essential mitotic kinases Plk1 and Aurora B. Surprisingly, stable depletion of Bub1 by ∼95% in human cells marginally affects whole chromosome segregation fidelity. We show that CENP-U, which is recruited to kinetochores by the CENP-P and CENP-Q subunits of the CENP-O complex, is required to prevent chromosome mis-segregation in Bub1-depleted cells. Mechanistically, Bub1 and CENP-U redundantly recruit Plk1 to kinetochores to stabilize kinetochore-microtubule attachments, thereby ensuring accurate chromosome segregation. Furthermore, unlike its budding yeast homolog, the CENP-O complex does not regulate centromeric localization of Aurora B. Consistently, depletion of Bub1 or CENP-U sensitizes cells to the inhibition of Plk1 but not Aurora B kinase activity. Taken together, our findings provide mechanistic insight into the regulation of kinetochore function, which may have implications for targeted treatment of cancer cells with mutations perturbing kinetochore recruitment of Plk1 by Bub1 or the CENP-O complex.

Activation of peroxymonosulfate by calcined electroplating sludge for ofloxacin degradation.

Developing cost-effective metal/metal oxides for peroxymonosulfate (PMS) activation remains a key issue in the sulfate radical based advanced oxidation process. In this work, electroplating sludge (ES), a transition metal-rich byproduct, was anaerobic calcined and characterized. Then, calcined electroplating sludge (CES) was applied as PMS activator for degradation of ofloxacin (OFL) and CES/PMS system exhibited a nearly 90% of OFL removal in 60 min. In addition, effect of CES, PMS, the initial pH and water constituents (chloride, bicarbonate, natural organic matter (NOM) and water backgrounds) on OFL degradation were systematically studied. Moreover, radical quenching tests and electron spin-resonance spectroscopy studies manifested that both SO4- and HO were the ruling reactive oxygen species. X-ray photoelectron spectroscopy results of the fresh and used CES demonstrated that the PMS activation mainly occur in the transformation from Fe3+ (Cu2+) to Fe2+ (Cu+). Furthermore, liquid chromatography coupled with ion trap time-of-flight mass spectrometry was used to illustrate the possible degradation pathway of OFL. Moreover, CES showed excellent stability and reusability during reaction. This work points out a new way for value-added reuse for ES as a cost-efficient activator of PMS for organic contaminant removal.

The complete chloroplast genome sequence of Citrus maxima (Burm.) Merr. 'Guanximiyou'.

Citrus maxima (Burm.) Merr. 'Guanximiyou' is a major citrus tree largely cultivated in China. A previous study has reported the complete chloroplast genome of C. maxima, but there may be some differences between wild species and cultivating variety. In this study, the complete chloroplast genome sequence of 'Guanximiyou' pummelo was characterized using BGISEQ-500 sequencing. The chloroplast genome was 160,186 bp in length and separated into four distinct regions such as large single-copy region (87,939 bp), small single-copy region (18,395 bp), and a pair of inverted repeat regions (26,926 bp). The genome contained a total of 109 genes including 79 protein-coding genes, 29 tRNA genes, and 4 rRNA genes. Phylogenetic maximum-likelihood analysis revealed that 'Guanximiyou' pummelo was clustered with other Rutaceae species with high bootstrap values.

Serum lipoprotein(a) and risk of periprocedural myocardial injury in patients undergoing percutaneous coronary intervention.

Recent studies and guidelines have indicated that lipoprotein(a) [Lp(a)]was an independent risk factor of arteriosclerotic cardiovascular disease (ASCVD). This study aimed to determine the relationship between serum Lp(a) levels and the risk of periprocedural myocardial injury following percutaneous coronary intervention (PCI) in coronary heartdisease (CHD) patients. This study enrolled 528 nonacute myocardial infarction (AMI) coronary heart disease (CHD) patients who successfully underwent PCI. Fasting serum lipids including Lp(a) were tested before PCI. High-sensitivity cardiac troponin I (hs-cTnI) was tested before PCI and 24 h after PCI. Univariate and multivariate logistic regression analyses were used to determine the relationship between preprocedural Lp(a) levels and postprocedural cTnI elevation from 1 × upper limit of normal (ULN) to 70 × ULN. As a continuous variable, multivariate analyses adjusting for conventional covariates and other serum lipids revealed that increased Lp(a) levels were independently associated with the risk of elevated postprocedural cTnI values above 1 × ULN (odds ratio [OR] per log-unit higher: 1.31, 95% confidence interval [CI]: 1.02-1.68, P = 0.033], 5 × ULN (OR: 1.25, 95%CI: 1.02-1.53, P = 0.032), 10 × ULN (OR: 1.48, 95%CI: 1.18-1.86, P = 0.001) and 15 × ULN (OR: 1.28, 95%CI: 1.01-1.61, P = 0.038). As a categorical variable, Lp(a) > 300 mg/L was an independent risk factor of postproceduralc TnI≥1 × ULN (OR 2.17, 95%CI 1.12-4.21, P = 0.022), ≥5 × ULN (OR 1.82, 95%CI 1.12-2.97, P = 0.017) and ≥10 × ULN (OR 2.17, 95%CI 1.33-3.54, P = 0.002). Therefore, it could be concluded that elevated preprocedural Lp(a) levels were associated with the risk of PCI-related myocardial injury in non-AMI CHD patients.

The dynamic relationship between state mindfulness and negative emotions.

The current study examines the dynamic influence of state mindfulness on negative emotions in daily life, and we developed two models to investigate their dynamic relationship after controlling the role of perceived stress. One hundred participants recruited from a Chinese university reported their daily and momentary emotions and their levels of state mindfulness five times per day for an entire week. Participants provided 3,177 valid responses, accounting for 90.77% of all required responses. Using a multilevel model, we found that (a) state mindfulness at Time t + 1 mediated the association between negative emotions at t and at t + 2, and the negative emotions encompasses three aspects (anxiety, depression, and sadness), and (b) negative emotion at t + 1 significantly mediated the association between state mindfulness at t and at t + 2. The current study showed that state mindfulness and negative emotions could reciprocally weaken each other, meaning that they demonstrate a counterproductive relationship.

Acetylcholine regulates the development of experimental autoimmune encephalomyelitis via the CD4+ cells proliferation and differentiation.

Purpose of the study: Multiple sclerosis is a CD4+ T cell mediated autoimmune disease characterized by inflammatory demyelination in the central nervous system. Acetylcholine (ACh) has been reported to be released by T lymphocytes and plays as an inflammation and immune regulator through the participation of T cells. However, both attenuated and aggravated effects of ACh in inflammation were found. The aim of this study is to further investigate the role of ACh in experimental autoimmune encephalomyelitis (EAE).Materials and methods: The left cervical vagotomy was performed to inhibit ACh release with the sham-operation as control. ACh in cerebral cortex and splenocytes culture supernatants of EAE mice were determined. Interleukin-6, interferon-γ, interleukin-4 and interleukin-17A in brain and splenocytes culture supernatants were evaluated by enzyme-linked immunosorbent assay. The proportion of CD4+ T cells and subsets were assessed by flow cytometry.Results: Compared with the sham-operation group, improved clinical and pathological parameters as well as decreased interleukin-6, interferon-γ, interleukin-4 and interleukin-17A were found in EAE mice with vagotomy suppressing the ACh. Marked reductions of CD4+ and CD4+ChAT+ cells, as well as significant decrease in Th1 with a bias to Th2 in Th1/Th2 balance and increased ChAT+Th2 proportion in the spleen were also observed in vagotomized mice.Conclusions: These findings emphasize that inhibiting ACh release by vagotomy can ameliorate the exacerbation of EAE through suppressing CD4+ T cells proliferation and regulating the differentiation of Th1, Th2 and Th17.

Centromere-localized Aurora B kinase is required for the fidelity of chromosome segregation.

Aurora B kinase plays an essential role in chromosome bi-orientation, which is a prerequisite for equal segregation of chromosomes during mitosis. However, it remains largely unclear whether centromere-localized Aurora B is required for faithful chromosome segregation. Here we show that histone H3 Thr-3 phosphorylation (H3pT3) and H2A Thr-120 phosphorylation (H2ApT120) can independently recruit Aurora B. Disrupting H3pT3-mediated localization of Aurora B at the inner centromere impedes the decline in H2ApT120 during metaphase and causes H2ApT120-dependent accumulation of Aurora B at the kinetochore-proximal centromere. Consequently, silencing of the spindle assembly checkpoint (SAC) is delayed, whereas the fidelity of chromosome segregation is negligibly affected. Further eliminating an H2ApT120-dependent pool of Aurora B restores proper timing for SAC silencing but increases chromosome missegregation. Our data indicate that H2ApT120-mediated localization of Aurora B compensates for the loss of an H3pT3-dependent pool of Aurora B to correct improper kinetochore-microtubule attachments. This study provides important insights into how centromeric Aurora B regulates SAC and kinetochore attachment to microtubules to ensure error-free chromosome segregation.

The ß-catenin/YAP signaling axis is a key regulator of melanoma-associated fibroblasts.

ß-catenin is a multifunctional protein that plays crucial roles in embryonic development, physiological homeostasis, and a wide variety of human cancers. Previously, we showed that in vivo targeted ablation of ß-catenin in melanoma-associated fibroblasts after melanoma formation significantly suppressed tumor growth. However, when the expression of ß-catenin was ablated in melanoma-associated fibroblasts before tumor initiation, melanoma development was surprisingly accelerated. How stromal ß-catenin deficiency leads to opposite biological effects in melanoma progression is not completely understood. Here, we report that ß-catenin is indispensable for the activation of primary human stromal fibroblasts and the mediation of fibroblast-melanoma cell interactions. Using coimmunoprecipitation and proximity ligation assays, we identified Yes-associated protein (YAP) as an important ß-catenin-interacting partner in stromal fibroblasts. YAP is highly expressed in the nuclei of cancer-associated fibroblasts (CAFs) in both human and murine melanomas. Mechanistic investigation revealed that YAP nuclear translocation is significantly modulated by Wnt/ß-catenin activity in fibroblasts. Blocking Wnt/ß-catenin signaling in stromal fibroblasts inhibited YAP nuclear translocation. In the absence of YAP, the ability of stromal fibroblasts to remodel the extracellular matrix (ECM) was inhibited, which is consistent with the phenotype observed in cells with ß-catenin deficiency. Further studies showed that the expression of ECM proteins and enzymes required for remodeling the ECM was suppressed in stromal fibroblasts after YAP ablation. Collectively, our data provide a new paradigm in which the ß-catenin-YAP signaling axis regulates the activation and tumor-promoting function of stromal fibroblasts.

Cancer-Associated Fibroblasts Build and Secure the Tumor Microenvironment.

Tumor cells reside in a highly complex and heterogeneous tumor microenvironment (TME), which is composed of a myriad of genetically stable non-cancer cells, including fibroblasts, immune cells, endothelial cells, and epithelial cells, and a tumor-specific extracellular matrix (ECM). Cancer-associated fibroblasts (CAFs), as an abundant and active stromal cell population in the TME, function as the signaling center and remodeling machine to aid the creation of a desmoplastic tumor niche. Although there is no denial that the TME and CAFs may have anti-tumor effects as well, a great deal of findings reported in recent years have convincingly revealed the tumor-promoting effects of CAFs and CAF-derived ECM proteins, enzymes, chemical factors and other downstream effectors. While there is growing enthusiasm for the development of CAF-targeting therapies, a better understanding of the complexities of CAF-ECM and CAF-cancer cell interactions is necessary before novel therapeutic strategies targeting the malignant tumor "soil" can be successfully implemented in the clinic.