AF1q is a universal marker of neuroblastoma that sustains N-Myc expression and drives tumorigenesis.

Neuroblastoma is the most common extracranial malignant tumor of childhood, accounting for 15% of all pediatric cancer deaths. Despite significant advances in our understanding of neuroblastoma biology, five-year survival rates for high-risk disease remain less than 50%, highlighting the importance of identifying novel therapeutic targets to combat the disease. MYCN amplification is the most frequent and predictive molecular aberration correlating with poor outcome in neuroblastoma. N-Myc is a short-lived protein primarily due to its rapid proteasomal degradation, a potentially exploitable vulnerability in neuroblastoma. AF1q is an oncoprotein with established roles in leukemia and solid tumor progression. It is normally expressed in brain and sympathetic neurons and has been postulated to play a part in neural differentiation. However, no role for AF1q in tumors of neural origin has been reported. In this study, we found AF1q to be a universal marker of neuroblastoma tumors. Silencing AF1q in neuroblastoma cells caused proteasomal degradation of N-Myc through Ras/ERK and AKT/GSK3ß pathways, activated p53 and blocked cell cycle progression, culminating in cell death via the intrinsic apoptotic pathway. Moreover, silencing AF1q attenuated neuroblastoma tumorigenicity in vivo signifying AF1q's importance in neuroblastoma oncogenesis. Our findings reveal AF1q to be a novel regulator of N-Myc and potential therapeutic target in neuroblastoma.

Gene therapy with AAV9-SGPL1 in an animal model of lung fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive scarring disease of the lung that leads rapidly to respiratory failure. Novel approaches to treatment are urgently needed. The bioactive lipid sphingosine-1-phosphate (S1P) is increased in IPF lungs and promotes proinflammatory and profibrotic TGF-ß signaling. Hence, decreasing lung S1P represents a potential therapeutic strategy for IPF. S1P is degraded by the intracellular enzyme S1P lyase (SPL). Here we find that a knock-in mouse with a missense SPL mutation mimicking human disease resulted in reduced SPL activity, increased S1P, increased TGF-ß signaling, increased lung fibrosis, and higher mortality after injury compared to wild type (WT). We then tested adeno-associated virus 9 (AAV9)-mediated overexpression of human SGPL1 (AAV-SPL) in mice as a therapeutic modality. Intravenous treatment with AAV-SPL augmented lung SPL activity, attenuated S1P levels within the lungs, and decreased injury-induced fibrosis compared to controls treated with saline or only AAV. We confirmed that AAV-SPL treatment led to higher expression of SPL in the epithelial and fibroblast compartments during bleomycin-induced lung injury. Additionally, AAV-SPL decreased expression of the profibrotic cytokines TNFα and IL1ß as well as markers of fibroblast activation, such as fibronectin (Fn1), Tgfb1, Acta2, and collagen genes in the lung. Taken together, our results provide proof of concept for the use of AAV-SPL as a therapeutic strategy for the treatment of IPF. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

AAV-SPL 2.0, a Modified Adeno-Associated Virus Gene Therapy Agent for the Treatment of Sphingosine Phosphate Lyase Insufficiency Syndrome.

Sphingosine-1-phosphate lyase insufficiency syndrome (SPLIS) is an inborn error of metabolism caused by inactivating mutations in SGPL1, the gene encoding sphingosine-1-phosphate lyase (SPL), an essential enzyme needed to degrade sphingolipids. SPLIS features include glomerulosclerosis, adrenal insufficiency, neurological defects, ichthyosis, and immune deficiency. Currently, there is no cure for SPLIS, and severely affected patients often die in the first years of life. We reported that adeno-associated virus (AAV) 9-mediated SGPL1 gene therapy (AAV-SPL) given to newborn Sgpl1 knockout mice that model SPLIS and die in the first few weeks of life prolonged their survival to 4.5 months and prevented or delayed the onset of SPLIS phenotypes. In this study, we tested the efficacy of a modified AAV-SPL, which we call AAV-SPL 2.0, in which the original cytomegalovirus (CMV) promoter driving the transgene is replaced with the synthetic "CAG" promoter used in several clinically approved gene therapy agents. AAV-SPL 2.0 infection of human embryonic kidney (HEK) cells led to 30% higher SPL expression and enzyme activity compared to AAV-SPL. Newborn Sgpl1 knockout mice receiving AAV-SPL 2.0 survived ≥ 5 months and showed normal neurodevelopment, 85% of normal weight gain over the first four months, and delayed onset of proteinuria. Over time, treated mice developed nephrosis and glomerulosclerosis, which likely resulted in their demise. Our overall findings show that AAV-SPL 2.0 performs equal to or better than AAV-SPL. However, improved kidney targeting may be necessary to achieve maximally optimized gene therapy as a potentially lifesaving SPLIS treatment.

Self-management interventions for people with pulmonary fibrosis: a scoping review.

BACKGROUND: The most effective method for encouraging self-management in individuals with pulmonary fibrosis (PF) is unclear. This review aimed to identify common self-management components, the outcome measures used and the impact of these components in PF. METHODS: A scoping review was conducted according to the Joanna Briggs Institute Manual for Evidence Synthesis using Medline, Embase, PsychInfo, CINAHL and the Cochrane Central Register of Controlled Trials. Eligible studies included those with educational, behavioural or support components aimed at facilitating self-management among adults with PF and employed quantitative and/or qualitative methods. RESULTS: 87 studies were included. Common self-management components included education (78%), managing physical symptoms (66%) and enhancing psychosocial wellbeing (54%). Components were predominantly delivered in a pulmonary rehabilitation setting (71%). No studies tested a PF-specific self-management package. Common outcome measures were 6-min walk distance (60%), St George's Respiratory Questionnaire (37%) and the Medical Research Council Dyspnoea scale (34%). Clinically significant improvements in these outcomes were seen in ≥50% of randomised controlled trials. Qualitative data highlighted the importance of healthcare professional and peer support and increased confidence in managing PF. CONCLUSION: Self-management components are commonly incorporated into pulmonary rehabilitation programmes rather than being offered as standalone packages. Future research should focus on testing PF-specific self-management packages and employ standardised outcome assessments that include self-efficacy and health-related behaviours.

Perceived Autonomy Support in Telerehabilitation by People With Chronic Respiratory Disease: A Mixed Methods Study.

BACKGROUND: Autonomy-supportive health environments can assist patients in achieving behavior change and can influence adherence positively. Telerehabilitation may increase access to rehabilitation services, but creating an autonomy-supportive environment may be challenging. RESEARCH QUESTION: To what degree does telerehabilitation provide an autonomy-supportive environment? What is the patient experience of an 8-week telerehabilitation program? STUDY DESIGN AND METHODS: Individuals undertaking telerehabilitation or center-based pulmonary rehabilitation within a larger randomized controlled equivalence trial completed the Health Care Climate Questionnaire (HCCQ; short form) to assess perceived autonomy support. Telerehabilitation participants were invited 1:1 to undertake semistructured interviews. Interviews were transcribed verbatim and coded thematically to identify major themes and subthemes. RESULTS: One hundred thirty-six participants (n = 69 telerehabilitation) completed the HCCQ and 30 telerehabilitation participants (42%) undertook interviews. HCCQ summary scores indicated that participants strongly agreed that the telerehabilitation environment was autonomy supportive, which was similar to center-based participants (HCCQ summary score, P = .6; individual HCCQ items, P ≥ .3). Telerehabilitation interview data supported quantitative findings identifying five major themes, with subthemes, as follows: (1) making it easier to participate in pulmonary rehabilitation, because telerehabilitation was convenient, saved time and money, and offered flexibility; (2) receiving support in a variety of ways, including opportunities for peer support and receiving an individualized program guided by expert staff; (3) internal and external motivation to exercise as a consequence of being in a supervised group, seeing results for effort, and being inspired by others; (4) achieving success through provision of equipment and processes to prepare and support operation of equipment and technology; and (5) after the rehabilitation program, continuing to exercise, but dealing with feelings of loss. INTERPRETATION: Telerehabilitation was perceived as an autonomy-supportive environment, in part by making it easier to undertake pulmonary rehabilitation. Support for behavior change, understanding, and motivation were derived from clinicians and patient-peers. The extent to which autonomy support translates into ongoing self-management and behavior change is not clear. TRIAL REGISTRY: Australian and New Zealand Clinical Trials Registry; No.: ACTRN12616000360415; URL: https://anzctr.org.au/.

Web-based physical activity promotion in young people with CF: a randomised controlled trial.

BACKGROUND: Physical activity levels are known to decline following hospitalisation for people with cystic fibrosis (pwCF). However, optimal physical activity promotion strategies are unclear. This study investigated the effect of a web-based application (ActivOnline) in promoting physical activity in young pwCF. METHODS: Multicentre randomised controlled trial with assessor blinding and qualitative evaluation. People with CF (12-35 years) admitted to hospital for a respiratory cause were eligible and randomised to the 12-week ActivOnline intervention (AO) or usual care (UC). The primary outcome was change in device-based time spent in moderate-to-vigorous physical activity (MVPA) from baseline to post-intervention. Follow-up was at 6 months from hospital discharge when qualitative evaluation was undertaken. RESULTS: 107 participants were randomised to AO (n=52) or UC (n=55). Sixty-three participants (59%) contributed to the intention-to-treat analysis. Mean (SD) age was 21 (6) years (n=46, <18 years). At baseline, physical activity levels were high in both groups (AO 102 (52) vs UC 127 (73) min/day). There was no statistically significant difference in MVPA between groups at either timepoint (post-intervention mean difference (95% CI) -14 mins (-45 to 16)). Uptake of the intervention was low with only 40% (n=21) of participants accessing the web application. CONCLUSION: A web-based application, including individualised goal setting, real-time feedback and motivation for behavioural change, was no better than usual care at promoting physical activity in young pwCF following hospital discharge. High levels of baseline physical activity levels in both groups, and limited engagement with the intervention, suggest alternative strategies may be necessary to identify and support young pwCF who would benefit from enhanced physical activity. TRIAL REGISTRATION NUMBER: ACTRN12617001009303, 13 July 13 2017.

Developing a self-management package for pulmonary fibrosis: an international Delphi study.

Rationale: Self-management is considered as an important part of disease management for people with pulmonary fibrosis (PF), but there is a lack of consensus regarding what components should be included. This study aimed to attain consensus from experts in PF and people living with the disease on the essential components and format of a PF self-management package. Methods: A two-round Delphi process was conducted. In each round, a panel of experts completed an online survey to rate a range of components, formats and delivery methods, followed by an online patient focus group to integrate patient perspectives. Consensus was defined a priori. Results: 45 experts participated in Round 1 and 51 in Round 2. Both focus groups included six people with PF. 12 components were considered essential for self-management in PF: 1) understanding treatment options; 2) understanding and accessing clinical trials; 3) managing medications; 4) role of oxygen therapy; 5) role and importance of pulmonary rehabilitation and regular physical activity; 6) managing shortness of breath; 7) managing fatigue; 8) managing mood; 9) managing comorbidities; 10) smoking cessation advice and support; 11) accessing community support; and 12) how to communicate with others when living with PF. Both groups agreed that self-management in PF required individualisation, goal setting and feedback. Conclusion: This study identified 12 essential components and highlighted individualisation, goal setting and feedback in self-management of PF. The findings provide a basis for the development of PF self-management interventions.

Self-management for pulmonary fibrosis: Insights from people living with the disease and healthcare professionals.

OBJECTIVE: People with pulmonary fibrosis (PF) consider self-management essential for maintaining health. This study aims to explore the needs and expectations of PF self-management from the patient and healthcare professionals (HCPs) perspectives. METHODS: Semi-structured interviews were conducted with people with PF and HCPs. Purposive sampling was used to recruit participants. Thematic analysis was performed using the principles of grounded theory. RESULTS: 18 individuals with PF and 15 HCPs were interviewed. Common self-management components reported included exercise, nutrition, maintaining healthy mind, avoiding infections, recognising deterioration and seeking help, managing symptoms and treatments, social support, and end-of-life planning. Both groups felt that effective self-management required individualised strategies, supports, and reliable information. People with PF identified access to personal health data and self-acceptance as part of self-management. HCPs highlighted the importance of accessible supports and managing patient expectations of disease course and treatments. Some HCPs concerned about missed detection of deterioration and suggested that self-management strategies for PF may differ to other lung diseases. CONCLUSION: This study identified components important for self-management in PF and provides a basis for designing a PF self-management package. PRACTICE IMPLICATIONS: Self-management of PF can be facilitated with individualised support from HCPs and reliable information that is accessible.

Structure-Based Design of Potent, Selective, and Orally Bioavailable VPS34 Kinase Inhibitors.

VPS34 is a class III phosphoinositide 3-kinase involved in endosomal trafficking and autophagosome formation. Inhibitors of VPS34 were believed to have value as anticancer agents, but genetic and pharmacological data suggest that sustained inhibition of VPS34 kinase activity may not be well tolerated. Here we disclose the identification of a novel series of dihydropyrazolopyrazinone compounds represented by compound 5 as potent, selective, and orally bioavailable VPS34 inhibitors through a structure-based design strategy. A water-interacting hydrogen bond acceptor within an appropriate distance to a hinge-binding element was found to afford significant VPS34 potency across chemical scaffolds. The selectivity of compound 5 over PIK family kinases arises from interactions between the hinge-binding element and the pseudo-gatekeeper residue Met682. As recent in vivo pharmacology data suggests that sustained inhibition of VPS34 kinase activity may not be tolerated, structure-activity relationships leading to VPS34 inhibition may be helpful for avoiding this target in other ATP-competitive kinase programs.

A mixed-methods pilot study of handheld fan for breathlessness in interstitial lung disease.

Dyspnoea is a cardinal symptom of fibrotic interstitial lung disease (ILD), with a lack of proven effective therapies. With emerging evidence of the role of facial and nasal airflow for relieving breathlessness, this pilot study was conducted to examine the feasibility of conducting a clinical trial of a handheld fan (HHF) for dyspnoea management in patients with fibrotic ILD. In this mixed-methods, randomised, assessor-blinded, controlled trial, 30 participants with fibrotic ILD who were dyspnoeic with a modified Medical Research Council Dyspnoea grade ≥ 2 were randomised to a HHF for symptom control or no intervention for 2 weeks. Primary outcomes were trial feasibility, change in Dyspnoea-12 scores at Week 2, and participants' perspectives on using a HHF for dyspnoea management. Study recruitment was completed within nine months at a single site. Successful assessor blinding was achieved in the fan group [Bang's Blinding Index - 0.08 (95% CI - 0.45, 0.30)] but not the control group [0.47 (0.12, 0.81)]. There were no significant between-group differences for the change in Dyspnoea-12 or secondary efficacy outcomes. During qualitative interviews, participants reported that using the HHF relieved breathlessness and provided relaxation, despite initial scepticism about its therapeutic benefit. Oxygen-experienced participants described the HHF being easier to use, but not as effective for symptomatic relief, compared to oxygen therapy. Our results confirmed the feasibility of a clinical trial of a HHF in fibrotic ILD. There was a high level of patient acceptance of a HHF for managing dyspnoea, with patients reporting both symptomatic benefits and ease of use.

Efficacy of AAV9-mediated SGPL1 gene transfer in a mouse model of S1P lyase insufficiency syndrome.

Sphingosine-1-phosphate lyase insufficiency syndrome (SPLIS) is a rare metabolic disorder caused by inactivating mutations in sphingosine-1-phosphate lyase 1 (SGPL1), which is required for the final step of sphingolipid metabolism. SPLIS features include steroid-resistant nephrotic syndrome and impairment of neurological, endocrine, and hematopoietic systems. Many affected individuals die within the first 2 years. No targeted therapy for SPLIS is available. We hypothesized that SGPL1 gene replacement would address the root cause of SPLIS, thereby serving as a universal treatment for the condition. As proof of concept, we evaluated the efficacy of adeno-associated virus 9-mediated transfer of human SGPL1 (AAV-SPL) given to newborn Sgpl1-KO mice that model SPLIS and die in the first weeks of life. Treatment dramatically prolonged survival and prevented nephrosis, neurodevelopmental delay, anemia, and hypercholesterolemia. STAT3 pathway activation and elevated proinflammatory and profibrogenic cytokines observed in KO kidneys were attenuated by treatment. Plasma and tissue sphingolipids were reduced in treated compared with untreated KO pups. SGPL1 expression and activity were measurable for at least 40 weeks. In summary, early AAV-SPL treatment prevents nephrosis, lipidosis, and neurological impairment in a mouse model of SPLIS. Our results suggest that SGPL1 gene replacement holds promise as a durable and universal targeted treatment for SPLIS.

Modeling the tumor immune microenvironment for drug discovery using 3D culture.

A few decades ago, the notion that a patient's own immune system could recognize and eliminate tumor cells was highly controversial; now, it is the basis for a thriving new field of cancer research, cancer immunology. With these new immune-based cancer treatments come the need for new complex preclinical models to assess their efficacy. Traditional therapeutics have often targeted the intrinsic growth of cancer cells and could, thus, be modeled with 2D monoculture. However, the next generation of therapeutics necessitates significantly greater complexity to model the ability of immune cells to infiltrate, recognize, and eliminate tumor cells. Modeling the physical and chemical barriers to immune infiltration requires consideration of extracellular matrix composition, architecture, and mechanobiology in addition to interactions between multiple cell types. Here, we give an overview of the unique properties of the tumor immune microenvironment, the challenges of creating physiologically relevant 3D culture models for drug discovery, and a perspective on future opportunities to meet this significant challenge.

Characteristics of Pulmonary Rehabilitation Programs Following an Exacerbation of Chronic Obstructive Pulmonary Disease: A SYSTEMATIC REVIEW.

PURPOSE: Early pulmonary rehabilitation (PR) has beneficial impacts on people with chronic obstructive pulmonary disease (COPD) when delivered after an exacerbation; however, program characteristics are diverse. This systematic review aimed to determine the impact of PR program characteristics (mode, length, commencement, frequency, location, and supervision) on clinical outcomes following an exacerbation of COPD. METHODS: Studies were screened from Medline, Medline in progress, Embase, CINAHL, SCOPUS, CENTRAL, and PEDro. Included studies were randomized controlled trials of early PR after an exacerbation of COPD (commenced during hospital stay or ≤4 wk of hospital discharge). The primary outcomes were hospital readmissions and mortality. RESULTS: Thirty studies were included. Exercise training alone was delivered in 43% of studies. Program duration varied from length of inpatient stay to 12 wk. The interventions commenced as early as ≤24 hr of hospitalization for acute exacerbation, and up to 2 wk after discharge. Early PR was compared to usual care, and no studies made a direct comparison of the program characteristics of interest. Program characteristics associated with reduced risk of hospital admission were commencement after hospital discharge, duration longer than 3 wk, and programs that included exercise training and education (relative risk of readmission range 0.6-0.79); however, it was not possible to determine which of these characteristics made the most important contribution. Mortality risk did not vary according to PR program characteristics. CONCLUSION: Programs >3 wk, started after hospital discharge or including an educational component in addition to exercise, were most effective at reducing hospital readmissions.

Top 10 research priorities for people living with pulmonary fibrosis, their caregivers, healthcare professionals and researchers.

INTRODUCTION: People with pulmonary fibrosis (PF) experience a high symptom burden, reduced quality of life and a shortened lifespan. Treatment options are limited and little is known about what patients, caregivers and healthcare professionals (HCPs)/researchers consider as the most important research priorities. This study aimed to identify the top 10 research priorities for PF across all stakeholders. METHODS: Participants included people with PF, caregivers and HCPs/researchers involved with PF. The research priority setting exercise involved three stages: (1) identifying priorities using an open-ended questionnaire and thematic analysis, (2) development of specific research questions at a face-to-face workshop, and (3) online ranking of research questions to identify the top 10 research priorities using nominal group ranking method. RESULTS: 196 participants completed stage 1 generating 560 questions and 14 research themes were identified. Stage 2 involved 32 participants and generated 53 indicative questions from which 39 were used for the final ranking. Stage 3 was completed by 270 participants. The top ranked priorities focussed on medications to reverse scarring in the lungs (ranked 1st), improving lung function (ranked 2nd, 6th and 8th), interventions aimed at alleviating symptoms (ranked 5th and 7th), prevention of PF (ranked 3rd and 4th) and the best exercise programme for PF (ranked 10th). There was good consensus among patients/carers and HCPs/researchers on the top 10 priorities, however, causes of acute exacerbations and early diagnosis for improving survival, was ranked higher by HCPs/researchers. CONCLUSION: Interventions for preserving lung health and alleviation of symptom burden were top research priorities for PF stakeholders.

The supportive care needs of people living with pulmonary fibrosis and their caregivers: a systematic review.

BACKGROUND: People with pulmonary fibrosis often experience a protracted time to diagnosis, high symptom burden and limited disease information. This review aimed to identify the supportive care needs reported by people with pulmonary fibrosis and their caregivers. METHODS: A systematic review was conducted according to PRISMA guidelines. Studies that investigated the supportive care needs of people with pulmonary fibrosis or their caregivers were included. Supportive care needs were extracted and mapped to eight pre-specified domains using a framework synthesis method. RESULTS: A total of 35 studies were included. The most frequently reported needs were in the domain of information/education, including information on supplemental oxygen, disease progression and prognosis, pharmacological treatments and end-of-life planning. Psychosocial/emotional needs were also frequently reported, including management of anxiety, anger, sadness and fear. An additional domain of "access to care" was identified that had not been specified a priori; this included access to peer support, psychological support, specialist centres and support for families of people with pulmonary fibrosis. CONCLUSION: People with pulmonary fibrosis report many unmet needs for supportive care, particularly related to insufficient information and lack of psychosocial support. These data can inform the development of comprehensive care models for people with pulmonary fibrosis and their loved ones.

Peer Connect Service for people with pulmonary fibrosis in Australia: Participants' experiences and process evaluation.

BACKGROUND AND OBJECTIVE: People living with pulmonary fibrosis (PF) report unmet needs for information and support. Lung Foundation Australia (LFA) have developed the Peer Connect Service to facilitate telephone support for people with PF across Australia. This project documented the experiences of participants and the resources required to support the service. METHODS: Consenting participants took part in semi-structured interviews by telephone. Primary peers (peers who agreed to initiate contact) and secondary peers (eligible patients who sought a peer match) were interviewed. Thematic analysis was undertaken by two independent researchers. Data were collected on the number of matches and contacts required to establish each match. RESULTS: Interviews were conducted with 32 participants (16 primary peers, 15 secondary peers and 1 who was both), aged from 53 to 89 years with 56% being male. Major themes included the value of shared experiences, providing mutual support and the importance of shared personal characteristics (e.g. gender and hobbies) in allowing information and emotional support needs to be met. Participants saw face-to-face contact with peers as highly desirable whilst acknowledging the practical difficulties. Primary peers were cognizant that their role was not to provide medical advice but to listen and share experiences. In the 12-month period, 60 peer matches were made, each match requiring a minimum of seven staff contacts. CONCLUSION: The Peer Connect Service provides a unique opportunity for people with PF to share experiences and offer mutual support. This telephone matching model may be useful in providing peer support for individuals with rare diseases who are geographically dispersed.

Identification of cell context-dependent YAP-associated proteins reveals ß1 and ß4 integrin mediate YAP translocation independently of cell spreading.

Yes-associated protein (YAP) is a transcriptional regulator and mechanotransducer, relaying extracellular matrix (ECM) stiffness into proliferative gene expression in 2D culture. Previous studies show that YAP activation is dependent on F-actin stress fiber mediated nuclear pore opening, however the protein mediators of YAP translocation remain unclear. Here, we show that YAP co-localizes with F-actin during activating conditions, such as sparse plating and culturing on stiff 2D substrates. To identify proteins mediating YAP translocation, we performed co-immunoprecipitation followed by mass spectrometry (co-IP/MS) for proteins that differentially associated with YAP under activating conditions. Interestingly, YAP preferentially associates with ß1 integrin under activating conditions, and ß4 integrin under inactivating conditions. In activating conditions, CRISPR/Cas9 knockout (KO) of ß1 integrin (ΔITGB1) resulted in decreased cell area, which correlated with decreased YAP nuclear localization. ΔITGB1 did not significantly affect the slope of the correlation between YAP nuclear localization with area, but did decrease overall nuclear YAP independently of cell spreading. In contrast, ß4 integrin KO (ΔITGB4) cells showed no change in cell area and similarly decreased nuclear YAP. These results reveal proteins that differentially associate with YAP during activation, which may aid in regulating YAP nuclear translocation.

Cell cycle progression in confining microenvironments is regulated by a growth-responsive TRPV4-PI3K/Akt-p27Kip1 signaling axis.

In tissues, cells reside in confining microenvironments, which may mechanically restrict the ability of a cell to double in size as it prepares to divide. How confinement affects cell cycle progression remains unclear. We show that cells progressed through the cell cycle and proliferated when cultured in hydrogels exhibiting fast stress relaxation but were mostly arrested in the G0/G1 phase of the cell cycle when cultured in hydrogels that exhibit slow stress relaxation. In fast-relaxing gels, activity of stretch-activated channels (SACs), including TRPV4, promotes activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which in turn drives cytoplasmic localization of the cell cycle inhibitor p27Kip1, thereby allowing S phase entry and proliferation. Cell growth during G1 activated the TRPV4-PI3K/Akt-p27Kip1 signaling axis, but growth is inhibited in the confining slow-relaxing hydrogels. Thus, in confining microenvironments, cells sense when growth is sufficient for division to proceed through a growth-responsive signaling axis mediated by SACs.

YAP-independent mechanotransduction drives breast cancer progression.

Increased tissue stiffness is a driver of breast cancer progression. The transcriptional regulator YAP is considered a universal mechanotransducer, based largely on 2D culture studies. However, the role of YAP during in vivo breast cancer remains unclear. Here, we find that mechanotransduction occurs independently of YAP in breast cancer patient samples and mechanically tunable 3D cultures. Mechanistically, the lack of YAP activity in 3D culture and in vivo is associated with the absence of stress fibers and an order of magnitude decrease in nuclear cross-sectional area relative to 2D culture. This work highlights the context-dependent role of YAP in mechanotransduction, and establishes that YAP does not mediate mechanotransduction in breast cancer.

Correction to: Sphingadienes show therapeutic efficacy in neuroblastoma in vitro and in vivo by targeting the AKT signaling pathway.

The authors would like to note an omission of disclosure in this paper. Author JDS is cofounder, equity-holder, and consultant of GILTRx Therapeutics.