Elevated hydrostatic pressure enhances the motility and enlarges the size of the lung cancer cells through aquaporin upregulation mediated by caveolin-1 and ERK1/2 signaling

Pressure loading regulates the stemness of liver cancer stem cells via YAP/BMF signaling axis

Cancer stem cells (CSCs) are considered the major cause of the occurrence, progression, chemoresistance/radioresistance, recurrence, and metastasis of cancer. Increased interstitial fluid pressure (IFP) is a key feature of solid tumors. Our previous study showed that the distribution of liver cancer stem cells (LCSCs) correlated with the mechanical heterogeneity within liver cancer tissues. However, the regulation of liver cancer's mechanical microenvironment on the LCSC stemness is not fully understood. Here, we employed a cellular pressure-loading device to investigate the effects of normal IFP (5 mmHg), as well as increased IFP (40 and 200 mmHg) on the stemness of LCSCs. Compared to the control LCSCs (exposure to 5 mmHg pressure loading), the LCSCs exposed to 40 mmHg pressure loading exhibited significantly upregulated expression of CSC markers (CD44, EpCAM, Nanog), enhanced sphere and colony formation capacities, and tumorigenic potential, whereas continuously increased pressure to 200 mmHg suppressed the LCSC characteristics. Mechanistically, pressure loading regulated Yes-associated protein (YAP) activity and Bcl-2 modifying factor (BMF) expression. YAP transcriptionally regulated BMF expression to affect the stemness of LCSCs. Knockdown of YAP and overexpression of BMF attenuated pressure-mediated stemness and tumorgenicity, while YAP-deficient and BMF-deletion recused pressure-dependent stemness on LCSCs, suggesting the involvement of YAP/BMF signaling axis in this process. Together, our findings provide a potential target for overcoming the stemness of CSCs and elucidate the significance of increased IFP in cancer progression.

Estimates of natural frequencies for nuclear vibration, and an assessment of the feasibility of selective ultrasound ablation of cancer cells

Selective ablation of cancer cells by ultrasound would be transformative for cancer therapy, but has not yet been possible. A key challenge is that cancerous and non-cancerous cells typically have similar acoustic impedance and are thus indistinguishable as materials in their responses to ultrasound. However, in certain cancers, cytoskeletal and nuclear lamin structures differ between healthy and malignant cells, opening the possibility of exploiting structural differences that manifest as different vibrational responses. To assess the possibility that the nuclei of certain cancerous cells might vibrate at different frequencies, we measured sizes and effective indentation moduli of a range of cancerous and non-cancerous cells from several cell lines and regions of the brain, and estimated the natural frequencies for nuclear vibration. Results suggest a potential difference in natural frequency for nuclear vibration between certain cancerous and non-cancerous cells, on the order of tens of kHz. This gap is potentially sufficient for selective ablation and motivates future experimentation on these specific cell types.

Confinement controls the directional cell responses to fluid forces

Our understanding of how fluid forces influence cell migration in confining environments remains limited. By integrating microfluidics with live-cell imaging, we demonstrate that cells in tightly-but not moderately-confined spaces reverse direction and move upstream upon exposure to fluid forces. This fluid force-induced directional change occurs less frequently when cells display diminished mechanosensitivity, experience elevated hydraulic resistance, or sense a chemical gradient. Cell reversal requires actin polymerization to the new cell front, as shown mathematically and experimentally. Actin polymerization is necessary for the fluid force-induced activation of NHE1, which cooperates with calcium to induce upstream migration. Calcium levels increase downstream, mirroring the subcellular distribution of myosin IIA, whose activation enhances upstream migration. Reduced lamin A/C levels promote downstream migration of metastatic tumor cells by preventing cell polarity establishment and intracellular calcium rise. This mechanism could allow cancer cells to evade high-pressure environments, such as the primary tumor.

The impact of tumor microenvironment: unraveling the role of physical cues in breast cancer progression

Metastasis accounts for the vast majority of breast cancer-related fatalities. Although the contribution of genetic and epigenetic modifications to breast cancer progression has been widely acknowledged, emerging evidence underscores the pivotal role of physical stimuli in driving breast cancer metastasis. In this review, we summarize the changes in the mechanics of the breast cancer microenvironment and describe the various forces that impact migrating and circulating tumor cells throughout the metastatic process. We also discuss the mechanosensing and mechanotransducing molecules responsible for promoting the malignant phenotype in breast cancer cells. Gaining a comprehensive understanding of the mechanobiology of breast cancer carries substantial potential to propel progress in prognosis, diagnosis, and patient treatment.

Toward innovative approaches for exploring the mechanically regulated tumor-immune microenvironment

Within the complex tumor microenvironment, cells experience mechanical cues-such as extracellular matrix stiffening and elevation of solid stress, interstitial fluid pressure, and fluid shear stress-that significantly impact cancer cell behavior and immune responses. Recognizing the significance of these mechanical cues not only sheds light on cancer progression but also holds promise for identifying potential biomarkers that would predict therapeutic outcomes. However, standardizing methods for studying how mechanical cues affect tumor progression is challenging. This challenge stems from the limitations of traditional in vitro cell culture systems, which fail to encompass the critical contextual cues present in vivo. To address this, 3D tumor spheroids have been established as a preferred model, more closely mimicking cancer progression, but they usually lack reproduction of the mechanical microenvironment encountered in actual solid tumors. Here, we review the role of mechanical forces in modulating tumor- and immune-cell responses and discuss how grasping the importance of these mechanical cues could revolutionize in vitro tumor tissue engineering. The creation of more physiologically relevant environments that better replicate in vivo conditions will eventually increase the efficacy of currently available treatments, including immunotherapies.

Biophysics in tumor growth and progression: from single mechano-sensitive molecules to mechanomedicine

Evidence from physical sciences in oncology increasingly suggests that the interplay between the biophysical tumor microenvironment and genetic regulation has significant impact on tumor progression. Especially, tumor cells and the associated stromal cells not only alter their own cytoskeleton and physical properties but also remodel the microenvironment with anomalous physical properties. Together, these altered mechano-omics of tumor tissues and their constituents fundamentally shift the mechanotransduction paradigms in tumorous and stromal cells and activate oncogenic signaling within the neoplastic niche to facilitate tumor progression. However, current findings on tumor biophysics are limited, scattered, and often contradictory in multiple contexts. Systematic understanding of how biophysical cues influence tumor pathophysiology is still lacking. This review discusses recent different schools of findings in tumor biophysics that have arisen from multi-scale mechanobiology and the cutting-edge technologies. These findings range from the molecular and cellular to the whole tissue level and feature functional crosstalk between mechanotransduction and oncogenic signaling. We highlight the potential of these anomalous physical alterations as new therapeutic targets for cancer mechanomedicine. This framework reconciles opposing opinions in the field, proposes new directions for future cancer research, and conceptualizes novel mechanomedicine landscape to overcome the inherent shortcomings of conventional cancer diagnosis and therapies.

Clinorotation inhibits myotube formation by fluid motion, not by simulated microgravity

To study processes related to weightlessness in ground-based cell biological research, a theoretically assumed microgravity environment is typically simulated using a clinostat - a small laboratory device that rotates cell culture vessels with the aim of averaging out the vector of gravitational forces. Here, we report that the rotational movement during fast clinorotation induces complex fluid motions in the cell culture vessel, which can trigger unintended cellular responses. Specifically, we demonstrate that suppression of myotube formation by 2D-clinorotation at 60 rpm is not an effect of the assumed microgravity but instead is a consequence of fluid motion. Therefore, cell biological results from fast clinorotation cannot be attributed to microgravity unless alternative explanations have been rigorously tested and ruled out. We consider two control experiments mandatory, i) a static, non-rotating control, and ii) a control for fluid motion. These control experiments are also highly recommended for other rotation speed settings and experimental conditions. Finally, we discuss strategies to minimize fluid motion in clinorotation experiments.

Expression of aquaporin 1, 3 and 5 in colorectal carcinoma: correlation with clinicopathological characteristics and prognosis

Background: Prognostic biomarkers in colorectal carcinoma (CRC) have an important role in therapeutic strategy. Studies have shown that high expression of Aquaporin (AQP) is associated with poor prognosis in a variety of human tumors. AQP is involved in the initiation and development of CRC. The present study aimed to investigate the correlation between the expression of AQP1, 3 and 5 and clinicopathological features or prognosis in CRC. Methods: The AQP1, 3 and 5 expressions were analyzed based on the immunohistochemical staining of tissue microarray specimens including 112 patients with CRC between June 2006 and November 2008. The expression score of AQP (Allred_score and H_score) was digitally obtained with Qupath software. Patients were divided into high or low expression subgroups based on the optimal cut-off values. The relationship between expression of AQP and clinicopathological characteristics were evaluated using chi-square test, t-test, or one-way ANOVA, when appropriate. Survival analysis of 5-year progression free survival (PFS) and overall survival (OS) was performed with time-dependent ROC, Kaplan-Meier curves, univariate and multivariate COX analysis. Results: The AQP1, 3 and 5 expressions were associated with regional lymph node metastasis, histological grading, and tumor location in CRC, respectively (p < 0.05). Kaplan-Meier curves showed that patients with high AQP1 expression had worse 5-year PFS than those with low AQP1 expression (Allred_score: 47% vs. 72%, p = 0.015; H_score: 52% vs. 78% p = 0.006), as well as 5-year OS (Allred_score: 51% vs. 75%, p = 0.005; H_score: 56% vs. 80%, p = 0.002). Multivariate Cox regression analysis indicated that AQP1 expression was an independent risk prognostic factor (p = 0.033, HR = 2.274, HR95% CI: 1.069-4.836). There was no significant correlation between the expression of AQP3 and 5 and the prognosis. Conclusion: The AQP1, 3 and 5 expressions correlate with different clinicopathological characteristics and the AQP1 expression may be a potential biomarker of prognosis in CRC.

Mechanotherapy in oncology: Targeting nuclear mechanics and mechanotransduction

Mechanotherapy is proposed as a new option for cancer treatment. Increasing evidence suggests that characteristic differences are present in the nuclear mechanics and mechanotransduction of cancer cells compared with those of normal cells. Recent advances in understanding nuclear mechanics and mechanotransduction provide not only further insights into the process of malignant transformation but also useful references for developing new therapeutic approaches. Herein, we present an overview of the alterations of nuclear mechanics and mechanotransduction in cancer cells and highlight their implications in cancer mechanotherapy.

Aquaporin-mediated dysregulation of cell migration in disease states

Dysregulated cell migration and invasion are hallmarks of many disease states. This dysregulated migratory behavior is influenced by the changes in expression of aquaporins (AQPs) that occur during pathogenesis, including conditions such as cancer, endometriosis, and arthritis. The ubiquitous function of AQPs in migration of diseased cells makes them a crucial target for potential therapeutics; this possibility has led to extensive research into the specific mechanisms underlying AQP-mediated diseased cell migration. The functions of AQPs depend on a diverse set of variables including cell type, AQP isoform, disease state, cell microenvironments, and even the subcellular localization of AQPs. To consolidate the considerable work that has been conducted across these numerous variables, here we summarize and review the last decade's research covering the role of AQPs in the migration and invasion of cells in diseased states.

Aquaporins in Tumor

Recent researches have demonstrated that aquaporins (AQPs), including water-selective channels, aquaglyceroporins and superaquaporins, are generally expressed in various tumors, such as lung, colorectal, liver, brain, breast tumors, etc. Therefore, it is imperative to study the accurate relationship between AQPs and tumor, which may provide innovative approaches to treat and prevent tumor development. In this chapter, we mainly reviewed the expression and pathophysiological function of AQPs in tumor, and summarize recent work on AQPs in tumor. Although, the underlying mechanism of AQP in tumor is not very clear, growing evidences suggest that cell migration, adhesion, angiogenesis, and division contribute to tumor development, in which AQPs might be involved. Therefore, it is still necessary to conduct further studies to determine the specific roles of AQPs in the tumor.

Hydrostatic pressure as a driver of cell and tissue morphogenesis

Morphogenesis, the process by which tissues develop into functional shapes, requires coordinated mechanical forces. Most current literature ascribes contractile forces derived from actomyosin networks as the major driver of tissue morphogenesis. Recent works from diverse species have shown that pressure derived from fluids can generate deformations necessary for tissue morphogenesis. In this review, we discuss how hydrostatic pressure is generated at the cellular and tissue level and how the pressure can cause deformations. We highlight and review findings demonstrating the mechanical roles of pressures from fluid-filled lumens and viscous gel-like components of the extracellular matrix. We also emphasise the interactions and mechanochemical feedbacks between extracellular pressures and tissue behaviour in driving tissue remodelling. Lastly, we offer perspectives on the open questions in the field that will further our understanding to uncover new principles of tissue organisation during development.

The interplay between physical cues and mechanosensitive ion channels in cancer metastasis

Physical cues have emerged as critical influencers of cell function during physiological processes, like development and organogenesis, and throughout pathological abnormalities, including cancer progression and fibrosis. While ion channels have been implicated in maintaining cellular homeostasis, their cell surface localization often places them among the first few molecules to sense external cues. Mechanosensitive ion channels (MICs) are especially important transducers of physical stimuli into biochemical signals. In this review, we describe how physical cues in the tumor microenvironment are sensed by MICs and contribute to cancer metastasis. First, we highlight mechanical perturbations, by both solid and fluid surroundings typically found in the tumor microenvironment and during critical stages of cancer cell dissemination from the primary tumor. Next, we describe how Piezo1/2 and transient receptor potential (TRP) channels respond to these physical cues to regulate cancer cell behavior during different stages of metastasis. We conclude by proposing alternative mechanisms of MIC activation that work in tandem with cytoskeletal components and other ion channels to bestow cells with the capacity to sense, respond and navigate through the surrounding microenvironment. Collectively, this review provides a perspective for devising treatment strategies against cancer by targeting MICs that sense aberrant physical characteristics during metastasis, the most lethal aspect of cancer.

Microfluidic Determination of Distinct Membrane Transport Properties between Lung Adenocarcinoma Cells CL1-0 and CL1-5

The cell membrane permeability of a cell type to water (Lp) and cryoprotective agents (Ps), is the key factor that determines the optimal cooling and mass transportation during cryopreservation. The human lung adenocarcinoma cell line, CL1, has been widely used to study the invasive capabilities or drug resistance of lung cancer cells. Therefore, providing accurate databases of the mass transport properties of this specific cell line can be crucial for facilitating either flexible and optimal preservation, or supply. In this study, utilizing our previously proposed noncontact-based micro-vortex system, we focused on comparing the permeability phenomenon between CL1-0 and its more invasive subline, CL1-5, under several different ambient temperatures. Through the assay procedure, the cells of favor were virtually trapped in a hydrodynamic circulation to provide direct inspection using a high-speed camera, and the images were then processed to achieve the observation of a cell’s volume change with respect to time, and in turn, the permeability. Based on the noncontact nature of our system, we were able to manifest more accurate results than their contact-based counterparts, excluding errors involved in estimating the cell geometry. As the results in this experiment showed, the transport phenomena in the CL1-0 and CL1-5 cell lines are mainly composed of simple diffusion through the lipid bilayer, except for the case where CL1-5 were suspended in the cryoprotective agent (CPA) solution, which also demonstrated higher Ps values. The deviated behavior of CL1-5 might be a consequence of the altered expression of aquaporins and the coupling of a cryoprotective agent and water, and has given a vision on possible studies over these properties, and their potential relationship to invasiveness and metastatic stability of the CL1 cell line.

The biophysics of cancer: emerging insights from micro- and nanoscale tools

Cancer is a complex and dynamic disease that is aberrant both biologically and physically. There is growing appreciation that physical abnormalities with both cancer cells and their microenvironment that span multiple length scales are important drivers for cancer growth and metastasis. The scope of this review is to highlight the key advancements in micro- and nano-scale tools for delineating the cause and consequences of the aberrant physical properties of tumors. We focus our review on three important physical aspects of cancer: 1) solid mechanical properties, 2) fluid mechanical properties, and 3) mechanical alterations to cancer cells. Beyond posing physical barriers to the delivery of cancer therapeutics, these properties are also known to influence numerous biological processes, including cancer cell invasion and migration leading to metastasis, and response and resistance to therapy. We comment on how micro- and nanoscale tools have transformed our fundamental understanding of the physical dynamics of cancer progression and their potential for bridging towards future applications at the interface of oncology and physical sciences.

Targeting ion channels for the treatment of lung cancer

Lung cancer is caused by several environmental and genetic variables and is globally associated with elevated morbidity and mortality. Among these variables, membrane-bound ion channels have a key role in regulating multiple signaling pathways in tumor cells and dysregulation of ion channel expression and function is closely related to proliferation, migration, and metastasis of lung cancer. This work reviews and summarizes current knowledge about the role of ion channels in lung cancer, focusing on the changes in the expression and function of various ion channels in lung cancer and how these changes affect lung cancer cell biology both in vitro and in vivo as evidenced by both genetic and pharmacological studies. It can help understand the molecular mechanisms of various ion channels influencing the initiation and progression of lung cancer and shed new insights into their roles in the development and treatment of this deadly disease.

Hydrostatic pressure stabilizes HIF‑1α expression in cancer cells to protect against oxidative damage during metastasis

The tissue microenvironment is known to play a pivotal role in cancer metastasis. Interstitial fluid hydrostatic pressure generally increases along with the rapid growth of malignant tumors. The aim of the present study was to investigate the role and relevant mechanism of elevated hydrostatic pressure in promoting the metastasis of cancer cells. Using a commercial device, Lewis lung cancer (LLC) cells were exposed to 50 mmHg hydrostatic pressure (HP) for 24 h. The survival time and morphology of the cells did not notably change; however, the results from a PCR array revealed the upregulation of numerous metastasis‑promoting genes (Hgf, Cdh11 and Ephb2) and the downregulation of metastasis suppressing genes (Kiss1, Syk and Htatip2). In addition, compared with that in the control, the cells which had undergone exposure to 50 mmHg HP showed significantly higher protein expression level of HIF‑1α and the antioxidant enzymes, SOD1 and SOD2, as well as improved tolerance to oxidative stress (P<0.05 vs. control). Following an intravenous injection of the LLC cells into healthy mice, to induce lung metastasis, it was found that the exposure of the LLC cells to 50 mmHg HP for 24 h, prior to injection into the mice, resulted in higher cell survival/retention in the lungs 24 h later and also resulted in more metastatic tumor lesions 4 weeks later (P<0.05 vs. control). Further investigation is required to confirm the molecular mechanism; however, the results from the present study suggested that elevated interstitial fluid HP in malignant tumors may promote the metastasis of cancer cells by stabilizing HIF‑1α expression to defend against oxidative damage.

Molecular cancer cell responses to solid compressive stress and interstitial fluid pressure

Alterations to the mechanical properties of the microenvironment are a hallmark of cancer. Elevated mechanical stresses exist in many solid tumors and elicit responses from cancer cells. Uncontrolled growth in confined environments gives rise to elevated solid compressive stress on cancer cells. Recruitment of leaky blood vessels and an absence of functioning lymphatic vessels causes a rise in the interstitial fluid pressure. Here we review the role of the cancer cell cytoskeleton and the nucleus in mediating both the initial and adaptive cancer cell response to these two types of mechanical stresses. We review how these mechanical stresses alter cancer cell functions such as proliferation, apoptosis, and migration.

Hydrostatic pressure promotes migration and filamin-A activation in fibroblasts with increased p38 phosphorylation and TGF-β production

Fibroblast migration is closely regulated by the mechanical characteristics in surrounding microenvironment. While increased interstitial hydrostatic pressure (HP) is a hallmark in many pathological and physiological conditions, little is known about how the HP affects fibroblast motility. Using cell-culture chips with elevated HP conditions, we showed that 20 cmH₂O HP significantly accelerated fibroblast migration. The HP-induced migration acceleration was dependent on the augmentation of transforming growth factor-β₁, and correlated with the activation of filamin A via the phosphorylation of p38 mitogen-activated protein kinase. Our results suggest that interstitial HP elevation associated with various pathological states could significantly regulate fibroblast migration.

Tissue engineered platforms for studying primary and metastatic neoplasm behavior in bone

Cancer is the second leading cause of death in the United States, claiming more than 560,000 lives each year. Osteosarcoma (OS) is the most common primary malignant tumor of bone in children and young adults, while bone is a common site of metastasis for tumors initiating from other tissues. The heterogeneity, continual evolution, and complexity of this disease at different stages of tumor progression drives a critical need for physiologically relevant models that capture the dynamic cancer microenvironment and advance chemotherapy techniques. Monolayer cultures have been favored for cell-based research for decades due to their simplicity and scalability. However, the nature of these models makes it impossible to fully describe the biomechanical and biochemical cues present in 3-dimensional (3D) microenvironments, such as ECM stiffness, degradability, surface topography, and adhesivity. Biomaterials have emerged as valuable tools to model the behavior of various cancers by creating highly tunable 3D systems for studying neoplasm behavior, screening chemotherapeutic drugs, and developing novel treatment delivery techniques. This review highlights the recent application of biomaterials toward the development of tumor models, details methods for their tunability, and discusses the clinical and therapeutic applications of these systems.

Caveolin-1 promotes radioresistance via IRGM-regulated autophagy in lung cancer

Background

Radiotherapy is the standard therapeutic approach for non-small cell lung cancers (NSCLCs). However, radiotherapy resistance accounts for major treatment failures in NSCLC patients. Recently, targeting autophagy-related signaling has shown potential to improve radiotherapy. Furthermore, some studies have reported that caveolin-1 (Cav1), a primary scaffolding protein of caveolae, is positively associated with NSCLC progression and cell autophagy. However, the function of Cav1-mediated autophagy in NSCLC radioresistance remains largely unknown.

Methods

The NSCLC irradiation (IR)-resistant cell lines H358-IRR and A549-IRR were used for in vitro analysis. Real-time quantitative PCR (qPCR), western blot, cell counting kit-8 (CCK-8), colony formation and transmission electron microscopy analyses were performed to explore the relationship between Cav1 and immunity-related GTPase family M protein (IRGM)-regulated autophagy in the radiation resistance of lung cancers.

Results

Cav1 was significantly overexpressed in H358-IRR and A549-IRR cells compared to their parental counterparts. Knockdown of Cav1 significantly decreased the proliferation of IR-resistant NSCLC cells. Combinational treatment of IR and siRNA of Cav1 showed enhanced inhibition of the cell viability and colony formation of IR-resistant NSCLC cells. In addition, Cav1 overexpression could upregulate the autophagic proteins microtubule associated protein 1 light chain 3 II (LC3 II), Beclin-1 and Sequestosome 1 (SQSTM1/p62) in parental NSCLC cells, while Cav1 downregulation by siRNA inhibited the expression of LC3 II, Beclin-1 and p62 and the formation of autophagosomes in IR-resistant NSCLC cells. Furthermore, we observed that IRGM was downregulated after knockdown of Cav1 in IR-resistant NSCLC cells. Thus, Cav1 was observed to promote autophagy and increase IR-resistant cell survival by targeting IRGM.

Conclusions

The results of our study showed that Cav1 is involved in the development of IR resistance in NSCLC through IRGM-regulated autophagy and can be considered as a potential therapeutic target for improving the radiosensitivity of NSCLC.

The importance of water and hydraulic pressure in cell dynamics

All mammalian cells live in the aqueous medium, yet for many cell biologists, water is a passive arena in which proteins are the leading players that carry out essential biological functions. Recent studies, as well as decades of previous work, have accumulated evidence to show that this is not the complete picture. Active fluxes of water and solutes of water can play essential roles during cell shape changes, cell motility and tissue function, and can generate significant mechanical forces. Moreover, the extracellular resistance to water flow, known as the hydraulic resistance, and external hydraulic pressures are important mechanical modulators of cell polarization and motility. For the cell to maintain a consistent chemical environment in the cytoplasm, there must exist an intricate molecular system that actively controls the cell water content as well as the cytoplasmic ionic content. This system is difficult to study and poorly understood, but ramifications of which may impact all aspects of cell biology from growth to metabolism to development. In this Review, we describe how mammalian cells maintain the cytoplasmic water content and how water flows across the cell surface to drive cell movement. The roles of mechanical forces and hydraulic pressure during water movement are explored.

Aquaporins in lung health and disease: Emerging roles, regulation, and clinical implications

Aquaporins (AQPs) aka water channels are a family of conserved transmembrane proteins (~30 kDa monomers) expressed in various organ systems. Of the 13 AQPs (AQP0 through AQP12) in the human body, four (AQPs 1, 3, 4, and 5) are expressed in the respiratory system. These channels are conventionally known for mediating transcellular fluid movements. Certain AQPs (aquaglyceroporins) have the capability to transport glycerol and potentially other solutes. There is an emerging body of literature unveiling the non-conventional roles of AQPs such as in cell proliferation and migration, gas permeation, signal potentiation, etc. Initial gene knock-out studies established a physiological role for lung AQPs, particularly AQP5, in maintaining homeostasis, by mediating fluid secretion from submucosal glands onto the airway surface liquid (ASL) lining. Subsequent studies have highlighted the functional significance of AQPs, particularly AQP1 and AQP5 in lung pathophysiology and diseases, including but not limited to chronic and acute lung injury, chronic obstructive pulmonary disease (COPD), other inflammatory lung conditions, and lung cancer. AQP1 has been suggested as a potential prognostic marker for malignant mesothelioma. Recent efforts are directed toward exploiting AQPs as targets for diagnosis, prevention, intervention, and/or treatment of various lung conditions. Emerging information on regulatory pathways and directed mechanistic research are posited to unravel novel strategies for these clinical implications. Future considerations should focus on development of AQP inhibitors, blockers, and modulators for therapeutic needs, and better understanding the role of lung-specific AQPs in inter-individual susceptibility to chronic lung diseases such as COPD and cancer.

Evaluation of cytotoxic T lymphocyte-mediated anticancer response against tumor interstitium-simulating physical barriers

Tumor antigen-specific cytotoxic T lymphocyte (CTL) is a promising agent for cancer therapy. Most solid tumors are characterized by increased interstitial fluid pressure (IFP) and dense collagen capsule, which form physical barriers to impede cancer treatment. However, it remains unclear how CTL-mediated anticancer response is affected at the presence of these obstacles. Using a microfluidic-based platform mimicking these obstacles, we investigated the migration characteristics and performance of anticancer response of CTLs targeting hepatic cancer cells via antigen-specific and allogeneic recognition. The device consisted of slit channels mimicking the narrow interstitial paths constrained by the fibrous capsule and increased IFP was simulated by applying hydrostatic pressure to the tumor center. We found that antigen-specificity of CTLs against the targeted cancer cells determined the cytotoxic efficacy of the CTLs but did not significantly affect the success rate in CTLs that attempted to infiltrate into the tumor center. When increased IFP was present in the tumor center, CTL recruitment to tumor peripheries was promoted but success of infiltration was hindered. Our results highlight the importance of incorporating the physical characteristics of tumor interstitum into the development of CTL-based cancer immunotherapy.

A role for caveola-forming proteins caveolin-1 and CAVIN1 in the pro-invasive response of glioblastoma to osmotic and hydrostatic pressure

In solid tumours, elevated interstitial fluid pressure (osmotic and hydrostatic pressure) is a barrier to drug delivery and correlates with poor prognosis. Glioblastoma (GBM) further experience compressive force when growing within a space limited by the skull. Caveolae are proposed to play mechanosensing roles, and caveola‐forming proteins are overexpressed in GBM. We asked whether caveolae mediate the GBM response to osmotic pressure. We evaluated in vitro the influence of spontaneous or experimental down‐regulation of caveola‐forming proteins (caveolin‐1, CAVIN1) on the proteolytic profile and invasiveness of GBM cells in response to osmotic pressure. In response to osmotic pressure, GBM cell lines expressing caveola‐forming proteins up‐regulated plasminogen activator (uPA) and/or matrix metalloproteinases (MMPs), some EMT markers and increased their in vitro invasion potential. Down‐regulation of caveola‐forming proteins impaired this response and prevented hyperosmolarity‐induced mRNA expression of the water channel aquaporin 1. CRISPR ablation of caveola‐forming proteins further lowered expression of matrix proteases and EMT markers in response to hydrostatic pressure, as a model of mechanical force. GBM respond to pressure by increasing matrix‐degrading enzyme production, mesenchymal phenotype and invasion. Caveola‐forming proteins mediate, at least in part, the pro‐invasive response of GBM to pressure. This may represent a novel target in GBM treatment.

Multifaceted Roles of Caveolin-1 in Lung Cancer: A New Investigation Focused on Tumor Occurrence, Development and Therapy

Lung cancer is one of the most common and malignant cancers with extremely high morbidity and mortality in both males and females. Although traditional lung cancer treatments are fast progressing, there are still limitations. Caveolin-1 (Cav-1), a main component of caveolae, participates in multiple cellular events such as immune responses, endocytosis, membrane trafficking, cellular signaling and cancer progression. It has been found tightly associated with lung cancer cell proliferation, migration, apoptosis resistance and drug resistance. In addition to this, multiple bioactive molecules have been confirmed to target Cav-1 to carry on their anti-tumor functions in lung cancers. Cav-1 can also be a predictor for lung cancer patients’ prognosis. In this review, we have summarized the valuable research on Cav-1 and lung cancer in recent years and discussed the multifaceted roles of Cav-1 on lung cancer occurrence, development and therapy, hoping to provide new insights into lung cancer treatment.

Inhaled gold nanoparticles cause cerebral edema and upregulate endothelial aquaporin 1 expression, involving caveolin 1 dependent repression of extracellular regulated protein kinase activity

Background

Gold nanoparticles (Au-NPs) have extensive applications in electronics and biomedicine, resulting in increased exposure and prompting safety concerns for human health. After absorption, nanoparticles enter circulation and effect endothelial cells. We previously showed that exposure to Au-NPs (40–50 nm) collapsed endothelial tight junctions and increased their paracellular permeability. Inhaled nanoparticles have gained significant attention due to their biodistribution in the brain; however, little is known regarding their role in cerebral edema. The present study investigated the expression of aquaporin 1 (AQP1) in the cerebral endothelial cell line, bEnd.3, stimulated by Au-NPs.

Results

We found that treatment with Au-NPs induced AQP1 expression and increased endothelial permeability to water. Au-NP exposure rapidly boosted the phosphorylation levels of focal adhesion kinase (FAK) and AKT, increased the accumulation of caveolin 1 (Cav1), and reduced the activity of extracellular regulated protein kinases (ERK). The inhibition of AKT (GDC-0068) or FAK (PF-573228) not only rescued ERK activity but also prevented AQP1 induction, whereas Au-NP-mediated Cav1 accumulation remained unaltered. Neither these signaling molecules nor AQP1 expression responded to Au-NPs while Cav1 was silenced. Inhibition of ERK activity (U0126) remarkably enhanced Cav1 and AQP1 expression in bEnd.3 cells. These data demonstrate that Au-NP-mediated AQP1 induction is Cav1 dependent, but requires the repression on ERK activity. Mice receiving intranasally administered Au-NPs displayed cerebral edema, significantly augmented AQP1 protein levels; furthermore, mild focal lesions were observed in the cerebral parenchyma.

Conclusions

These data suggest that the subacute exposure of nanoparticles might induce cerebral edema, involving the Cav1 dependent accumulation on endothelial AQP1.

Comprehensive characterization of the alternative splicing landscape in head and neck squamous cell carcinoma reveals novel events associated with tumorigenesis and the immune microenvironment

Alternative splicing (AS) has emerged as a key event in tumor development and microenvironment formation. However, comprehensive analysis of AS and its clinical significance in head and neck squamous cell carcinoma (HNSC) is urgently required. Methods: Genome-wide profiling of AS events using RNA-Seq data from The Cancer Genome Atlas (TCGA) program was performed in a cohort of 464 patients with HNSC. Cancer-associated AS events (CASEs) were identified between paired HNSC and adjacent normal tissues and evaluated in functional enrichment analysis. Splicing networks and prognostic models were constructed using bioinformatics tools. Unsupervised clustering of the CASEs identified was conducted and associations with clinical, molecular and immune features were analyzed. Results: We detected a total of 32,309 AS events and identified 473 CASEs in HNSC; among these, 91 were validated in an independent cohort (n = 15). Functional protein domains were frequently altered, especially by CASEs affecting cancer drivers, such as PCSK5. CASE parent genes were significantly enriched in pathways related to HNSC and the tumor immune microenvironment, such as the viral carcinogenesis (FDR < 0.001), Human Papillomavirus infection (FDR < 0.001), chemokine (FDR < 0.001) and T cell receptor (FDR < 0.001) signaling pathways. CASEs enriched in immune-related pathways were closely associated with immune cell infiltration and cytolytic activity. AS regulatory networks suggested a significant association between splicing factor (SF) expression and CASEs and might be regulated by SF methylation. Eighteen CASEs were identified as independent prognostic factors for overall and disease-free survival. Unsupervised clustering analysis revealed distinct correlations between AS-based clusters and prognosis, molecular characteristics and immune features. Immunogenic features and immune subgroups cooperatively depict the immune features of AS-based clusters. Conclusion: This comprehensive genome-wide analysis of the AS landscape in HNSC revealed novel AS events related to carcinogenesis and immune microenvironment, with implications for prognosis and therapeutic responses.

Regulation of Epithelial Cell Functions by the Osmolality and Hydrostatic Pressure Gradients: A Possible Role of the Tight Junction as a Sensor

Epithelia act as a barrier to the external environment. The extracellular environment constantly changes, and the epithelia are required to regulate their function in accordance with the changes in the environment. It has been reported that a difference of the environment between the apical and basal sides of epithelia such as osmolality and hydrostatic pressure affects various epithelial functions including transepithelial transport, cytoskeleton, and cell proliferation. In this paper, we review the regulation of epithelial functions by the gradients of osmolality and hydrostatic pressure. We also examine the significance of this regulation in pathological conditions especially focusing on the role of the hydrostatic pressure gradient in the pathogenesis of carcinomas. Furthermore, we discuss the mechanism by which epithelia sense the osmotic and hydrostatic pressure gradients and the possible role of the tight junction as a sensor of the extracellular environment to regulate epithelial functions.

Regulation of Cell Behavior by Hydrostatic Pressure

Hydrostatic pressure (HP) regulates diverse cell behaviors including differentiation, migration, apoptosis, and proliferation. Abnormal HP is associated with pathologies including glaucoma and hypertensive fibrotic remodeling. In this review, recent advances in quantifying and predicting how cells respond to HP across several tissue systems are presented, including tissues of the brain, eye, vasculature and bladder, as well as articular cartilage. Finally, some promising directions on the study of cell behaviors regulated by HP are proposed.

Does fluid collection impact radiotherapy outcomes after wide excision of lower extremity soft tissue sarcoma?

Background

Fluid collection (FC) of lymph or blood may accumulate at the site of excision after surgery for soft tissue sarcoma, with reported incidence rates from 10% to 36%. The purpose of this study is to analyze the impact of FC on local recurrence (LR) and wound complication rates after adjuvant postoperative radiotherapy (PORT) in lower extremity soft tissue sarcoma (LE-STS).

Methods

Eighty-eight patients diagnosed with LE-STS were curatively treated with wide excision and PORT. FC developed in 51.1% of patients. Full FC volumes were included in the irradiation field throughout the full course of PORT for 36 patients (80.0%). A median of 61.2 and 63 Gy was prescribed for patients with and without FC, respectively.

Results

After a median follow-up of 4.3 years, patients with and without FC had 5-year local control rates of 77.7% and 90.8% (P = 0.105). Eight patients with FC had LR, of which six patients had recurrent tumors at or within 4 cm of the FC wall and three of these patients had out-of-field LR. Wound complication occurred after RT in 3 (6.7%) of 45 patients with FC and 1 (2.3%) of 43 patients without FC.

Conclusions

FC presents a potential risk for increased LR, particularly near the FC wall. Based on reasonable wound complication rates, we suggest the need and feasibility of fully including FC volumes in the irradiation field.

The effect of the rate of hydrostatic pressure depressurization on cells in culture

Changes in hydrostatic pressure, at levels as low as 10 mm Hg, have been reported in some studies to alter cell function in vitro; however, other studies have found no detectable changes using similar methodologies. We here investigate the hypothesis that the rate of depressurization, rather than elevated hydrostatic pressure itself, may be responsible for these reported changes. Hydrostatic pressure (100 mm Hg above atmospheric pressure) was applied to bovine aortic endothelial cells (BAECs) and PC12 neuronal cells using pressurized gas for periods ranging from 3 hours to 9 days, and then the system was either slowly (~30 minutes) or rapidly (~5 seconds) depressurized. Cell viability, apoptosis, proliferation, and F-actin distribution were then assayed. Our results did not show significant differences between rapidly and slowly depressurized cells that would explain differences previously reported in the literature. Moreover, we found no detectable effect of elevated hydrostatic pressure (with slow depressurization) on any measured variables. Our results do not confirm the findings of other groups that modest increases in hydrostatic pressure affect cell function, but we are not able to explain their findings.