Pharmacological blockade of aquaporin-1 water channel by AqB013 restricts migration and invasiveness of colon cancer cells and prevents endothelial tube formation in vitro

The water channels aquaporin-1 and aquaporin-3 interact with and affect the cell polarity protein Scribble in 3D in vitro models of breast cancer

Cellular changes in carcinomas include alterations in cell proliferation, cell migration, cell-cell adhesion, and cellular polarity. In vitro studies have revealed that the water channels, aquaporin-1 (AQP1) and AQP3, can influence cell migration and cell-cell adhesion. Of note, we previously showed that AQP1 overexpression reduced levels of cell-cell adhesion proteins, whereas AQP3 increased levels when overexpressed in normal epithelial cells. Expression of AQP1 and AQP3 in breast carcinoma is associated with lymph node metastasis, recurrence, and poor survival of patients with breast cancer. In this study, we investigated if AQP1 and AQP3 affected cell polarity in breast cancer by studying the relationship between the major polarity protein Scribble and AQP1 and AQP3. In breast cancer tissue samples, the protein expression of AQP1, AQP3, and Scribble did not show an obvious correlation. However, in a GST pull-down assay, AQP1 and AQP3 interacted with Scribble. AQP1 overexpression reduced the size of 3D spheroids as well as reduced Scribble levels at cell-cell contacts, whereas AQP3 overexpression showed no significant change in spheroid size compared with control, AQP3 overexpression also reduced Scribble levels at cell-cell contacts. Of note, AQP1 overexpression increased cell migration and induced cell detachment and dissemination from migrating breast cancer cell sheets, whereas AQP3 overexpression did not. Thus, AQP1 and AQP3 differentially affect 3D-grown breast cancer spheroids, and especially AQP1 may contribute to cancer development and spread via negatively affecting cellular junctions and cell polarity proteins as well as increasing cell migration and cell detachment.NEW & NOTEWORTHY Overexpression of the water channels aquaporin-1 and aquaporin-3 reduced levels of the key polarity protein Scribble at cell-cell junctions, suggesting potential implications in breast cancer progression and metastasis.

Aquaporins in colorectal cancer: exploring their role in tumorigenesis, metastasis, and drug response

Aquaporins (AQPs) are small, integral proteins facilitating water transport across plasma cell membranes in response to osmotic gradients. This family has 13 unique members (AQP0-12), which can also transport glycerol, urea, gases, and other salute small molecules. AQPs play a crucial role in the regulation of different cellular processes, including metabolism, migration, immunity, barrier function, and angiogenesis. These proteins are found to aberrantly overexpress in various cancers, including colorectal cancer (CRC). Growing evidence has explored AQPs as a potential diagnostic biomarker and therapeutic target in different cancers. However, there is no comprehensive review compiling the available information on the crucial role of AQPs in the context of colorectal cancer. This review highlights the significance of AQPs as the biomarker and regulator of tumor cells metabolism. In addition, the proliferation, angiogenesis, and metastasis of tumor cells related to AQPs expression as well as function are discussed. Understanding the AQPs prominent role in chemotherapy resistance is of great importance clinically.

Overexpression of aquaporin-1 plays a vital role in proliferation, apoptosis, and pyroptosis of Wilms' tumor cells

BACKGROUND

Nephroblastoma, also known as Wilms' tumor (WT), is an embryonic malignant tumor and one of the most common malignant tumors in the abdominal region of children. The exact role and underlying mechanisms of aquaporin-1 (AQP1) in the occurrence and development of nephroblastoma remain unclear.

METHODS

After overexpression of AQP1, cell proliferation was assessed using the CCK-8 proliferation assay and EdU staining. Flow cytometry was employed to assess cell apoptosis, and Western blotting (WB) analysis was conducted to validate the expression of relevant protein markers. mRNA sequencing (mRNA-Seq) was performed on WT cells overexpressing AQP1 to predict and characterize the associated mechanisms. Transmission electron microscopy was utilized to observe changes in the ultrastructure of WT cells undergoing apoptosis and pyroptosis following AQP1 overexpression. Functional in vivo validation was conducted through animal experiments.

RESULTS

We validated that overexpression of AQP1 inhibited cell proliferation and promoted cell apoptosis and pyroptosis both in vitro and in vivo. mRNA-Seq analysis of WT cells with AQP1 overexpression suggested that these effects might be mediated through the inhibition of the JAK-STAT signaling pathway. Additionally, we discovered that overexpression of AQP1 activated the classical pyroptosis signaling pathway dependent on caspase-1, thereby promoting pyroptosis in WT.

CONCLUSION

These findings highlight the important functional role of AQP1 in the pathobiology of nephroblastoma, providing novel insights into the development of this disease. Moreover, these results offer new perspectives on the potential therapeutic targeting of AQP1 as a treatment strategy for nephroblastoma.

From Homeostasis to Pathology: Decoding the Multifaceted Impact of Aquaporins in the Central Nervous System

Aquaporins (AQPs), integral membrane proteins facilitating selective water and solute transport across cell membranes, have been the focus of extensive research over the past few decades. Particularly noteworthy is their role in maintaining cellular homeostasis and fluid balance in neural compartments, as dysregulated AQP expression is implicated in various degenerative and acute brain pathologies. This article provides an exhaustive review on the evolutionary history, molecular classification, and physiological relevance of aquaporins, emphasizing their significance in the central nervous system (CNS). The paper journeys through the early studies of water transport to the groundbreaking discovery of Aquaporin 1, charting the molecular intricacies that make AQPs unique. It delves into AQP distribution in mammalian systems, detailing their selective permeability through permeability assays. The article provides an in-depth exploration of AQP4 and AQP1 in the brain, examining their contribution to fluid homeostasis. Furthermore, it elucidates the interplay between AQPs and the glymphatic system, a critical framework for waste clearance and fluid balance in the brain. The dysregulation of AQP-mediated processes in this system hints at a strong association with neurodegenerative disorders such as Parkinson's Disease, idiopathic normal pressure hydrocephalus, and Alzheimer's Disease. This relationship is further explored in the context of acute cerebral events such as stroke and autoimmune conditions such as neuromyelitis optica (NMO). Moreover, the article scrutinizes AQPs at the intersection of oncology and neurology, exploring their role in tumorigenesis, cell migration, invasiveness, and angiogenesis. Lastly, the article outlines emerging aquaporin-targeted therapies, offering a glimpse into future directions in combatting CNS malignancies and neurodegenerative diseases.

Loss of aquaporin-1 expression is associated with worse clinical outcomes in clear cell renal cell carcinoma: an immunohistochemical study

BACKGROUND

Aquaporin (AQP) expression has been investigated in various malignant neoplasms, and the overexpression of AQP is related to poor prognosis in some malignancies. However, the expression of AQP protein in clear cell renal cell carcinoma (ccRCC) has not been extensively investigated by immunohistochemistry with large sample size.

METHODS

We evaluated the AQP expression in 827 ccRCC with immunohistochemical staining in tissue microarray blocks and classified the cases into two categories, high and low expression.

RESULTS

High expression of aquaporin-1 (AQP1) was found in 320 cases (38.7%), but aquaporin-3 was not expressed in ccRCC. High AQP1 expression was significantly related to younger age, low TNM stage, low World Health Organization/International Society of Urologic Pathology nuclear grade, and absence of distant metastasis. Furthermore, high AQP1 expression was also significantly associated with longer overall survival (OS; p<.001) and progression-specific survival (PFS; p<.001) and was an independent predictor of OS and PFS in ccRCC.

CONCLUSIONS

Our study revealed the prognostic significance of AQP1 protein expression in ccRCC. These findings could be applied to predict the prognosis of ccRCC.

Berberine Inhibited Growth and Migration of Human Colon Cancer Cell Lines by Increasing Phosphatase and Tensin and Inhibiting Aquaporins 1, 3 and 5 Expressions

Introduction: Berberine is a natural isoquinoline alkaloid with anti-cancer properties. Nevertheless, the underlying mechanism of its action in human colorectal cancer (CRC) has not been thoroughly elucidated. We investigated the anti-cancer effect of berberine on HT-29, SW-480 and HCT-116 human CRC cell lines. Methods: Cell proliferation, migration and invasion were studied by MTT assay, wound healing, transwell chambers and flow cytometry. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunostaining were used to evaluate the expression of aquaporins (AQPs) 1, 3 and 5 in colon cancer cell lines before and after treatment with berberine (10, 30 and 100 µM). RT-qPCR and Western blotting were used to further explore the PI3K/AKT signaling pathway and the molecular mechanisms underlying berberine-induced inhibition of cell proliferation. Results: We demonstrated that treatment of these CRC cell lines with berberine inhibited cell proliferation, migration and invasion through induction of apoptosis and necrosis. HT-29, SW-480 and HCT-116 stained positively for AQP 1, 3 and 5, and berberine treatment down-regulated the expression of all three types of AQPs. Berberine also modulated PI3K/AKT pathway activity through up-regulating PTEN and down-regulating PI3K, AKT and p-AKT expression as well as suppressing its downstream targets, mTOR and p-mTOR at the protein level. Discussion/Conclusions: These findings indicate that berberine inhibited growth, migration and invasion of these colon cancer cell lines via down-regulation of AQP 1, 3 and 5 expressions, up-regulating PTEN which inhibited the PI3K/AKT pathway at the gene and protein levels, and that AQP 1, 3 and 5 expression level can be used as prognostic biomarkers for colon cancer metastasis.

A novel immune score model predicting the prognosis and immunotherapy response of breast cancer

Breast cancer (BC) is one of the most common malignancies. However, the existing pathological grading system cannot accurately and effectively predict the survival rate and immune checkpoint treatment response of BC patients. In this study, based on The Cancer Genome Atlas (TCGA) database, a total of 7 immune-related genes (IRGs) were screened out to construct a prognostic model. Subsequently, the clinical prognosis, pathological characteristics, cancer-immunity cycle, tumour immune dysfunction and exclusion (TIDE) score, and immune checkpoint inhibitor (ICI) response were compared between the high- and low-risk groups. In addition, we determined the potential regulatory effect of NPR3 on BC cell proliferation, migration, and apoptosis. The model consisting of 7 IRGs was an independent prognostic factor. Patients with lower risk scores exhibited longer survival times. Moreover, the expression of NPR3 was increased but the expression of PD-1, PD-L1, and CTLA-4 was decreased in the high-risk group compared to the low-risk group. In addition, compared with si-NC, si-NPR3 suppressed proliferation and migration but promoted apoptosis in both MDA-MB-231 and MCF-7 cells. This study presents a model for predicting survival outcomes and provides a strategy to guide effective personalized immunotherapy in BC patients.

Relevant Membrane Transport Proteins as Possible Gatekeepers for Effective Pharmacological Ascorbate Treatment in Cancer

Despite the increasing number of newly diagnosed malignancies worldwide, therapeutic options for some tumor diseases are unfortunately still limited. Interestingly, preclinical but also some clinical data suggest that the administration of pharmacological ascorbate seems to respond well, especially in some aggressively growing tumor entities. The membrane transport and channel proteins are highly relevant for the use of pharmacological ascorbate in cancer therapy and are involved in the transfer of active substances such as ascorbate, hydrogen peroxide, and iron that predominantly must enter malignant cells to induce antiproliferative effects and especially ferroptosis. In this review, the relevant conveying proteins from cellular surfaces are presented as an integral part of the efficacy of pharmacological ascorbate, considering the already known genetic and functional features in tumor tissues. Accordingly, candidates for diagnostic markers and therapeutic targets are mentioned.

Forensic application of aquaporins

Aquaporins (AQPs) are a family of water channel proteins that primarily elicit the basic functions of water transport and osmotic homeostasis. To date, at least 17 mammalian AQPs have been identified, AQP-0 to -12 have been found in higher orders including human, and AQP-13 to -16 have been described in older lineages. Moreover, these proteins have recently been shown to regulate many biological processes through unique activities, such as cell proliferation, migration, apoptosis, and mitochondrial metabolism. Several studies have focused on the involvement of AQPs in cell biology aspect, showing that they are involved in a variety of physiological processes and pathophysiological conditions. Furthermore, in the field of forensic medicine, studies on whether AQPs can be a useful marker for diagnosing various causes of death have been conducted using autopsy samples and animal experiments, which have produced interesting results. Herein, we review certain observations regarding AQPs and discuss their potential to contribute to the future practice of forensic research.

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.

The Interplay between Aquaporin-1 and the Hypoxia-Inducible Factor 1α in a Lipopolysaccharide-Induced Lung Injury Model in Human Pulmonary Microvascular Endothelial Cells

Aquaporin-1 (AQP1), a water channel, and the hypoxia-inducible factor 1α (HIF1A) are implicated in acute lung injury responses, modulating among others pulmonary vascular leakage. We hypothesized that the AQP1 and HIF1A systems interact, affecting mRNA, protein levels and function of AQP1 in human pulmonary microvascular endothelial cells (HPMECs) exposed to lipopolysaccharide (LPS). Moreover, the role of AQP1 in apoptosis and wound healing progression was examined. Both AQP1 mRNA and protein expression levels were higher in HPMECs exposed to LPS compared to untreated HPMECs. However, in the LPS-exposed HIF1A-silenced cells, the mRNA and protein expression levels of AQP1 remained unaltered. In the permeability experiments, a statistically significant volume increase was observed at the 360 s time-point in the LPS-exposed HPMECs, while LPS-exposed HIF1A-silenced HPMECs did not exhibit cell swelling, implying a dysfunctional AQP1. AQP1 did not seem to affect cell apoptosis yet could interfere with endothelial migration and/or proliferation. Based on our results, it seems that HIF1A silencing negatively affects AQP1 mRNA and protein expression, as well as AQP1 function, in the setting of lung injury.

Simple and automatic monitoring of cancer cell invasion into an epithelial monolayer using label-free holographic microscopy

The invasiveness of cancer cells describes the metastasizing capability of a primary tumor. The straightforward detection and quantification of cancer cell invasion are important to predict the survival rate of a cancer patient and to test how anti-cancer compounds influence cancer progression. Digital holographic microscopy based M4 Holomonitor (HM) is a technique that allows the label-free monitoring of cell morphological and kinetical parameters in real-time. Here, a fully confluent epithelial monolayer derived from the African green monkey kidney (Vero) on a gelatin-coated surface was established, then HeLa cells were seeded on top of the monolayer, and their behavior was monitored for 24 h using HM. Several cancer cells showing invasiveness were detected during this period, while other HeLa cells did not show any signs of aggressivity. It was demonstrated that the invasion of single cancer cells is soundly observable and also quantifiable through monitoring parameters such as phase shift, optical volume, area, and motility, which parameters can easily be obtained and processed automatically. Based on the experimental data, the invasion speed of cancer cells entering the epithelial layer can be defined as the shrinking of detected single-cell volume per unit time. The invasion speed and its correlation with cell migration parameters were analyzed in depth. A clear linear relationship between migration and invasion speed was found, cancer cells with stronger migration have slower invasion speed. These results not only describe the effect of how cancer cells invade the underlying monolayer in contrast to non-invasive HeLa cells, but could help in future research to optimize drugs affecting cell invasibility in a fully automated, label-free and high-throughput manner.

Aquaporin-6 May Increase the Resistance to Oxidative Stress of Malignant Pleural Mesothelioma Cells

Malignant pleural mesothelioma (MPM) is an aggressive cancer of the pleural surface and is associated with previous asbestos exposure. The chemotherapy drug is one of the main treatments, but the median survival ranges from 8 to 14 months from diagnosis. The redox homeostasis of tumor cells should be carefully considered since elevated levels of ROS favor cancer cell progression (proliferation and migration), while a further elevation leads to ferroptosis. This study aims to analyze the functioning/role of aquaporins (AQPs) as a hydrogen peroxide (H₂O₂) channel in epithelial and biphasic MPM cell lines, as well as their possible involvement in chemotherapy drug resistance. Results show that AQP-3, -5, -6, -9, and -11 were expressed at mRNA and protein levels. AQP-6 was localized in the plasma membrane and intracellular structures. Compared to normal mesothelial cells, the water permeability of mesothelioma cells is not reduced by exogenous oxidative stress, but it is considerably increased by heat stress, making these cells resistant to ferroptosis. Functional experiments performed in mesothelioma cells silenced for aquaporin-6 revealed that it is responsible, at least in part, for the increase in H₂O₂ efflux caused by heat stress. Moreover, mesothelioma cells knocked down for AQP-6 showed a reduced proliferation compared to mock cells. Current findings suggest the major role of AQP-6 in providing mesothelioma cells with the ability to resist oxidative stress that underlies their resistance to chemotherapy drugs.

Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease

The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.

Pathophysiological role of ion channels and transporters in HER2-positive breast cancer

The incidence of breast cancer (BC) has been increasing each year, and BC is now the most common malignant tumor in women. Among the numerous BC subtypes, HER2-positive BC can be treated with a variety of strategies based on targeting HER2. Although there has been great progress in the treatment of HER2-positive BC, recurrence, metastasis and drug resistance remain considerable challenges. The dysfunction of ion channels and transporters can affect the development and progression of HER2-positive BC, so these entities are expected to be new therapeutic targets. This review summarizes various ion channels and transporters associated with HER2-positive BC and suggests potential targets for the development of new and effective therapies.

Peroxiporins Are Induced upon Oxidative Stress Insult and Are Associated with Oxidative Stress Resistance in Colon Cancer Cell Lines

Oxidative stress can induce genetic instability and change cellular processes, resulting in colorectal cancer. Additionally, adaptation of oxidative defense causes therapy resistance, a major obstacle in successful cancer treatment. Peroxiporins are aquaporin membrane channels that facilitate H2O2 membrane permeation, crucial for regulating cell proliferation and antioxidative defense. Here, we investigated four colon cancer cell lines (Caco-2, HT-29, SW620, and HCT 116) for their sensitivity to H2O2, cellular antioxidative status, and ROS intracellular accumulation after H2O2 treatment. The expression of peroxiporins AQP1, AQP3, and AQP5 and levels of NRF2, the antioxidant transcription factor, and PPARγ, a transcription factor that regulates lipid metabolism, were evaluated before and after oxidative insult. Of the four tested cell lines, HT-29 was the most resistant and showed the highest expression of all tested peroxiporins and the lowest levels of intracellular ROS, without differences in GSH levels, catalase activity, nor NF2 and PPARγ levels. Caco-2 shows high expression of AQP3 and similar resistance as HT-29. These results imply that oxidative stress resistance can be obtained by several mechanisms other than the antioxidant defense system. Regulation of intracellular ROS through modulation of peroxiporin expression may represent an additional strategy to target the therapy resistance of cancer cells.

Dose Response of Bumetanide on Aquaporins and Angiogenesis Biomarkers in Human Retinal Endothelial Cells Exposed to Intermittent Hypoxia

Aquaporins (AQPs) are important for regulating cellular water, solute transport, and balance. Recently, AQPs have also been recognized as playing a key role in cell migration and angiogenesis. In the retina, hypoxia induces vascular endothelial growth factor (VEGF), a potent angiogenic and vascular permeability factor, resulting in retinal edema, which is facilitated by AQPs. Bumetanide is a diuretic agent and AQP 1–4 blocker. We tested the hypothesis that bumetanide suppression of AQPs ameliorates intermittent hypoxia (IH)-induced angiogenesis and oxidative stress in human microvascular retinal endothelial cells (HMRECs). HMRECs were treated with a low-dose (0.05 µg/mL) or high-dose (0.2 µg/mL) of bumetanide and were exposed to normoxia (Nx), hyperoxia (50% O₂), or IH (50% O₂ with brief hypoxia 5% O₂) for 24, 48, and 72 h. Angiogenesis and oxidative stress biomarkers were determined in the culture media, and the cells were assessed for tube formation capacity and AQP-1 and -4 expression. Both doses of bumetanide significantly decreased oxidative stress and angiogenesis biomarkers. This response was reflected by reductions in tube formation capacity and AQP expression. These findings confirm the role of AQPs in retinal angiogenesis. Therapeutic targeting of AQPs with bumetanide may be advantageous for IH-induced aberrant retinal development.

MicroRNA-133a-3p inhibits cell proliferation, migration and invasion in colorectal cancer by targeting AQP1

Recently, miR-133a-3p has been identified as a marker for human colorectal cancer (CRC) and the association between miR-133a-3p and aquaporin 1 (AQP1) has been described in endothelial cells. However, the regulatory functions of the miR-133a-3p/AQP1 axis remain unclear in CRC. The present study analyzed the expression of miR-133a-3p and AQP1 in CRC tissues (n=56) and cell lines using reverse transcription-quantitative PCR and western blot analysis. The χ2 test was used to assess the associations between miR-133a-3p/AQP1 and clinicopathological features of patients with CRC. Next, the functional role of miR-133a-3p/AQP1 in CRC was evaluated in vitro by performing Cell Counting Kit-8 and Transwell assays. Moreover, the online software tool TargetScan7.1 was used to predict AQP1 as the target gene of miR-133a-3p, followed by validation using a luciferase reporter assay. The results showed that miR-133a-3p was significantly downregulated, while AQP1 was upregulated in CRC tissues and cell lines compared with corresponding controls. Clinically, it was demonstrated that miR-133a-3p/AQP1 expression was significantly associated with tumor TNM stage (P=0.020). Functional experiments indicated that miR-133a-3p-overexpression remarkably suppressed, while knockdown promoted, cell proliferation, migration and invasion in CRC cells. Mechanically, AQP1 was identified and validated as a target gene of miR-133a-3p in CRC cells. The expression level of AQP1 mRNA was not correlated with miR-133a-3p expression in CRC tissues. Furthermore, AQP1-knockdown induced, while overexpression reversed, the suppressive effects of miR-133a-3p on CRC cells. Taken together, these findings suggested that miR-133a-3p might be a tumor suppressor by suppressing cell proliferation, migration and invasion via targeting AQP1.

In Vitro Synergistic Inhibition of HT-29 Proliferation and 2H-11 and HUVEC Tubulogenesis by Bacopaside I and II Is Associated with Ca2+ Flux and Loss of Plasma Membrane Integrity

We previously showed how triterpene saponin bacopaside (bac) II, purified from the medicinal herb Bacopa monnieri, induced cell death in colorectal cancer cell lines and reduced endothelial cell migration and tube formation, and further demonstrated a synergistic effect of a combination of bac I and bac II on the inhibition of breast cancer cell line growth. Here, we assessed the effects of bac I and II on the colorectal cancer HT-29 cell line, and mouse (2H-11) and human umbilical vein endothelial cell (HUVEC) lines, measuring outcomes including cell viability, proliferation, migration, tube formation, apoptosis, cytosolic Ca²⁺ levels and plasma membrane integrity. Combined bac I and II, each applied at concentrations below IC₅₀ values, caused a synergistic reduction of the viability and proliferation of HT-29 and endothelial cells, and impaired the migration of HT-29 and tube formation of endothelial cells. A significant enhancement of apoptosis was induced only in HUVEC, although an increase in cytosolic Ca²⁺ was detected in all three cell lines. Plasma membrane integrity was compromised in 2H-11 and HUVEC, as determined by an increase in propidium iodide staining, which was preceded by Ca²⁺ flux. These in vitro findings support further research into the mechanisms of action of the combined compounds for potential clinical use.

AQP3 and AQP5-Potential Regulators of Redox Status in Breast Cancer

Breast cancer is still one of the leading causes of mortality in the female population. Despite the campaigns for early detection, the improvement in procedures and treatment, drastic improvement in survival rate is omitted. Discovery of aquaporins, at first described as cellular plumbing system, opened new insights in processes which contribute to cancer cell motility and proliferation. As we discover new pathways activated by aquaporins, the more we realize the complexity of biological processes and the necessity to fully understand the pathways affected by specific aquaporin in order to gain the desired outcome-remission of the disease. Among the 13 human aquaporins, AQP3 and AQP5 were shown to be significantly upregulated in breast cancer indicating their role in the development of this malignancy. Therefore, these two aquaporins will be discussed for their involvement in breast cancer development, regulation of oxidative stress and redox signalling pathways leading to possibly targeting them for new therapies.

AQP1 Is Up-Regulated by Hypoxia and Leads to Increased Cell Water Permeability, Motility, and Migration in Neuroblastoma

The water channel aquaporin 1 (AQP1) has been implicated in tumor progression and metastasis. It is hypothesized that AQP1 expression can facilitate the transmembrane water transport leading to changes in cell structure that promote migration. Its impact in neuroblastoma has not been addressed so far. The objectives of this study have been to determine whether AQP1 expression in neuroblastoma is dependent on hypoxia, to demonstrate whether AQP1 is functionally relevant for migration, and to further define AQP1-dependent properties of the migrating cells. This was determined by investigating the reaction of neuroblastoma cell lines, particularly SH-SY5Y, Kelly, SH-EP Tet-21/N and SK-N-BE(2)-M17 to hypoxia, quantitating the AQP1-related water permeability by stopped-flow spectroscopy, and studying the migration-related properties of the cells in a modified transwell assay. We find that AQP1 expression in neuroblastoma cells is up-regulated by hypoxic conditions, and that increased AQP1 expression enabled the cells to form a phenotype which is associated with migratory properties and increased cell agility. This suggests that the hypoxic tumor microenvironment is the trigger for some tumor cells to transition to a migratory phenotype. We demonstrate that migrating tumor cell express elevated AQP1 levels and a hypoxic biochemical phenotype. Our experiments strongly suggest that elevated AQP1 might be a key driver in transitioning stable tumor cells to migrating tumor cells in a hypoxic microenvironment.

Aquaporins and diseases pathogenesis: From trivial to undeniable involvements, a disease-based point of view

Aquaporins (AQPs), as transmembrane proteins, were primarily identified as water channels with the ability of regulating the transmission of water, glycerol, urea, and other small-sized molecules. The classic view of AQPs involvement in therapeutic plan restricted them and their regulators into managing only a narrow spectrum of the diseases such as diabetes insipidus and the syndrome of inappropriate ADH secretion. However, further investigations performed, especially in the third millennium, has found that their cooperation in water transmission control can be manipulated to handle other burden-imposing diseases such as cirrhosis, heart failure, Meniere's disease, cancer, bullous pemphigoid, eczema, and Sjögren's syndrome.

Targeting Aquaporins in Novel Therapies for Male and Female Breast and Reproductive Cancers

Aquaporins are membrane channels in the broad family of major intrinsic proteins (MIPs), with 13 classes showing tissue-specific distributions in humans. As key physiological modulators of water and solute homeostasis, mutations, and dysfunctions involving aquaporins have been associated with pathologies in all major organs. Increases in aquaporin expression are associated with greater severity of many cancers, particularly in augmenting motility and invasiveness for example in colon cancers and glioblastoma. However, potential roles of altered aquaporin (AQP) function in reproductive cancers have been understudied to date. Published work reviewed here shows distinct classes aquaporin have differential roles in mediating cancer metastasis, angiogenesis, and resistance to apoptosis. Known mechanisms of action of AQPs in other tissues are proving relevant to understanding reproductive cancers. Emerging patterns show AQPs 1, 3, and 5 in particular are highly expressed in breast, endometrial, and ovarian cancers, consistent with their gene regulation by estrogen response elements, and AQPs 3 and 9 in particular are linked with prostate cancer. Continuing work is defining avenues for pharmacological targeting of aquaporins as potential therapies to reduce female and male reproductive cancer cell growth and invasiveness.

Anti-Angiogenic Properties of Ginsenoside Rg3

Ginsenoside Rg3 (Rg3) is a member of the ginsenoside family of chemicals extracted from Panax ginseng. Like other ginsenosides, Rg3 has two epimers: 20(S)-ginsenoside Rg3 (SRg3) and 20(R)-ginsenoside Rg3 (RRg3). Rg3 is an intriguing molecule due to its anti-cancer properties. One facet of the anti-cancer properties of Rg3 is the anti-angiogenic action. This review describes the controversies on the effects and effective dose range of Rg3, summarizes the evidence on the efficacy of Rg3 on angiogenesis, and raises the possibility that Rg3 is a prodrug.

Aquaporin-1 facilitates proliferation and invasion of gastric cancer cells via GRB7-mediated ERK and Ras activation

Gastric cancer, one of the most common malignant tumors of the digestive tract, is devoid of effective treatment owing to its highly invasive ability. Aquaporins (AQPs), transmembrane water channel proteins, has been shown to be involved in the malignancy of gastric cancer. This study aims to investigate the pathophysiological roles of AQP-1 in gastric cancer. We first demonstrated quantitative real-time polymerase chain reaction analysis and found up-regulation of AQP-1 in gastric cancer cell lines. Additionally, silence of AQP-1 inhibited cell proliferation via decrease of proliferating cell nuclear antigen (PCNA) and minichromosome maintenance complex component 2 (MCM2). Moreover, migration and invasion of gastric cancer cells were also suppressed by the interference of AQP-1. However, the tumorigenic mechanism of AQP-1 on gastric cancer is yet to be found. We demonstrated western blot analysis and found that knockdown of AQP-1 decreased protein expression of phospho (p)-GRB7 (growth factor receptor-bound protein 7) and led to a remarkable reduction of p-extracellular signal-regulated kinase (ERK) via inactivation of RAS. In general, our findings indicated that AQP-1 facilitates proliferation and invasion of gastric cancer cells via GRB7-mediated ERK and Ras activation, illuminating a novel AQP-1-RAS/ERK molecular axis as regulator in gastric cancer progression and suggesting potential implications in the treatment of gastric cancer.

Overexpression of Aquaporin 1 in Synovium Aggravates Rat Collagen-Induced Arthritis Through Regulating β-Catenin Signaling: An in vivo and in vitro Study

Introduction

Previous studies have confirmed that aquaporin 1 (AQP1) is up-regulated in synovium of rheumatoid arthritis (RA), but its exact pathogenic mechanisms in RA are unclear. This study revealed the pathogenic role of AQP1 in rat collagen-induced arthritis (CIA) and the underlying mechanisms related to β-catenin signaling.

Materials and Methods

Secondary paw swelling and pathological changes of ankle joints were used to evaluate the severity of rat CIA. Synovial AQP1 and β-catenin expression were measured by immunohistochemistry (IHC) and Western blot assay. AQP1 siRNA was applied to knockdown AQP1 in cultured CIA fibroblast-like synoviocyte (FLS). Assays of MTT, PCNA immunofluorescence and transwell were performed to detect cell proliferation, migration and invasion. The protein levels of β-catenin pathway members and ratio of TOP/FOP luciferase activity were also measured.

Results

In vivo, we revealed that synovial AQP1 and β-catenin expressions in CIA rats were higher than normal rats, and synovial AQP1 expression of CIA rats increased in parallel with secondary paw swelling and total pathological score on joint damage. Correlation analysis of IHC results indicated that synovial AQP1 expression positively correlated with β-catenin expression in CIA rat. In vitro, AQP1 siRNA apparently reduced the proliferation, migration and invasion of CIA FLS by inhibiting β-catenin signaling pathway. As an activator of β-catenin signaling, lithium chloride (an inhibitor of GSK-3β) reversed the inhibitory effects of AQP1 siRNA on the cultured CIA FLS.

Conclusion

We concluded that the overexpression of synovial AQP1 aggravated rat CIA by promoting the activation of FLS through β-catenin signaling pathway.

ERCC1, PARP-1, and AQP1 as predictive biomarkers in colon cancer patients receiving adjuvant chemotherapy

BACKGROUND

The recognition of high-risk colon cancer patients prone to chemoresistant and recurrent disease is a challenge.

OBJECTIVES

We aimed to assess the immunohistochemical expression of ERCC1, PARP-1, and AQP1 in 60 cases of stage II and III colon cancer who underwent curative resection and adjuvant chemotherapy. Their predictive role of tumor progression and disease-free survival (DFS) was analyzed.

METHODS

The immunohistochemical expression of ERCC1, PARP-1, and AQP1 in 60 cases of stage II and III colon cancer who underwent curative resection and adjuvant chemotherapy was studied. The collected data on the overall survival (OS), disease-free survival (DFS), and the response to the chemotherapy were analyzed.

RESULTS

Positive nuclear ERCC1 expression was identified in 58.3% of the patients, ERCC1 expression was significantly associated with left-sided tumors (P< 0.01). Moreover, its expression was significantly associated with the aggressive tumor characteristics including high grade, lymph node metastasis and advanced tumor stage (P< 0.001 for each). High nuclear PARP-1 expression was observed in 63.3% of the cases, and its expression was significantly associated with tumor grade and lymph node metastasis (P= 0.003 for each). Positive membranous AQP1 expression was identified in 41.7% of patients, and it was associated with high grade, lymph node metastasis and advanced tumor stage (P< 0.001 for each). During the follow-up period, 23 patients (38.3%) exhibited a tumor progression; this was significantly associated with positive ERCC1, high PARP-1, and negative AQP1 expression. Statistics of the survival data revealed that shorter DFS was significantly associated with positive ERCC1, high PARP-1, and positive AQP1 expression (P= 0.005, 0.016, 0.002, respectively).

CONCLUSIONS

ERCC1, PARP1, and AQP1 are adverse prognostic biomarkers in stage II-III colon cancer. Moreover, adjuvant chemotherapy may not be beneficial for patients with positive ERCC1, high PARP1, and AQP1-negative tumors. Therefore, we recommend that ERCC1, PARP-1, and AQP1 should be assessed during the selection of the treatment strategy for stage II-III colon cancer patients.

Combined Systematic Review and Transcriptomic Analyses of Mammalian Aquaporin Classes 1 to 10 as Biomarkers and Prognostic Indicators in Diverse Cancers

Aquaporin (AQP) channels enable regulated transport of water and solutes essential for fluid homeostasis, but they are gaining attention as targets for anticancer therapies. Patterns of AQP expression and survival rates for patients were evaluated by systematic review (PubMed and Embase) and transcriptomic analyses of RNAseq data (Human Protein Atlas database). Meta-analyses confirmed predominantly negative associations between AQP protein and RNA expression levels and patient survival times, most notably for AQP1 in lung, breast and prostate cancers; AQP3 in esophageal, liver and breast cancers; and AQP9 in liver cancer. Patterns of AQP expression were clustered for groups of cancers and associated with risk of death. A quantitative transcriptomic analysis of AQP1-10 in human cancer biopsies similarly showed that increased transcript levels of AQPs 1, 3, 5 and 9 were most frequently associated with poor survival. Unexpectedly, increased AQP7 and AQP8 levels were associated with better survival times in glioma, ovarian and endometrial cancers, and increased AQP11 with better survival in colorectal and breast cancers. Although molecular mechanisms of aquaporins in pathology or protection remain to be fully defined, results here support the hypothesis that overexpression of selected classes of AQPs differentially augments cancer progression. Beyond fluid homeostasis, potential roles for AQPs in cancers (suggested from an expanding appreciation of their functions in normal tissues) include cell motility, membrane process extension, transport of signaling molecules, control of proliferation and apoptosis, increased mechanical compliance, and gas exchange. AQP expression also has been linked to differences in sensitivity to chemotherapy treatments, suggesting possible roles as biomarkers for personalized treatments. Development of AQP pharmacological modulators, administered in cancer-specific combinations, might inspire new interventions for controlling malignant carcinomas.

Physiological and pathophysiological role of ion channels and transporters in the colorectum and colorectal cancer

The incidence of colorectal cancer has increased annually, and the pathogenesis of this disease requires further investigation. In normal colorectal tissues, ion channels and transporters maintain the water‐electrolyte balance and acid/base homeostasis. However, dysfunction of these ion channels and transporters leads to the development and progression of colorectal cancer. Therefore, this review focuses on the progress in understanding the roles of ion channels and transporters in the colorectum and in colorectal cancer, including aquaporins (AQPs), Cl⁻ channels, Cl⁻/HCO3‐ exchangers, Na⁺/HCO3‐ transporters and Na⁺/H⁺ exchangers. The goal of this review is to promote the identification of new targets for the treatment and prognosis of colorectal cancer.

Based on Histogram Analysis: ADCaqp Derived from Ultra-high b-Value DWI could be a Non-invasive Specific Biomarker for Rectal Cancer Prognosis

Aquaporins (AQP) are not only water channel protein, but also potential prognostic indicator and therapeutic target for rectal cancer. Some previous studies have demonstrated the AQP expression could be estimated by ADC_aqp value derived from ultra-high b-value diffusion-weighted imaging (DWI). We aim to determine whether ADC_aqp could be a new and specific biomarker for indicating the AQP expression and prognostic factors of rectal cancer. 76 untreated patients with rectal cancer confirmed by colonoscopy biopsy were enrolled. ADC_aqp value was generated from ultra-high b-value DWI with five b-values (1700–3500 s/mm²). AQP (AQP1, 3 and 5)staining intensity was estimated by both of software (QuPath) and manual manner. The relationships between histogram features of ADC_aqp and AQP staining intensity were analyzed. The correlations between histogram features of ADC_aqp and differentiation degrees (good, moderate, poor), T stage (T1–2 vs T3–4), and lymph node status (N+ vs N−) were also evaluated respectively. The mean, 75^th percentile and 97.5^th percentile of ADC_aqp were correlated with AQP1 staining intensity (r = 0.237, 0.323 and 0.362, respectively, all P < 0.05) . No correlation was found between the histogram features of ADC_aqp and AQP3 or AQP5 staining intensity. The mean, 50^th percentile, 75^th percentile and 97.5^th percentile of ADC_aqp value exhibited significant differences between differentiation status (all P < 0.05). Histogram features of ADC_aqp value showed no significant differences in two subgroups of T stage and lymph node status (all P > 0.05). Histogram analysis showed that the ADC_aqp value derived from ultra-high b-value DWI of rectal cancer could reflect AQP1’s expression and rectal cancer’s malignancy degree. ADC_aqp might be a new imaging biomarker for evaluating rectal cancer.

5-Hydroxymethyl-Furfural and Structurally Related Compounds Block the Ion Conductance in Human Aquaporin-1 Channels and Slow Cancer Cell Migration and Invasion

Aquaporin-1 (AQP1) dual water and ion channels enhance migration and invasion when upregulated in leading edges of certain classes of cancer cells. Work here identifies structurally related furan compounds as novel inhibitors of AQP1 ion channels. 5-Hydroxymethyl-2-furfural (5HMF), a component of natural medicinal honeys, and three structurally related compounds, 5-nitro-2-furoic acid (5NFA), 5-acetoxymethyl-2-furaldehyde (5AMF), and methyl-5-nitro-2-furoate (M5NF), were analyzed for effects on water and ion channel activities of human AQP1 channels expressed in Xenopus oocytes. Two-electrode voltage clamp showed dose-dependent block of the AQP1 ion current by 5HMF (IC₅₀ 0.43 mM), 5NFA (IC₅₀ 1.2 mM), and 5AMF (IC₅₀ ∼3 mM) but no inhibition by M5NF. In silico docking predicted the active ligands interacted with glycine 165, located in loop D gating domains surrounding the intracellular vestibule of the tetrameric central pore. Water fluxes through separate intrasubunit pores were unaltered by the furan compounds (at concentrations up to 5 mM). Effects on cell migration, invasion, and cytoskeletal organization in vitro were tested in high-AQP1-expressing cancer lines, colon cancer (HT29) and AQP1-expressing breast cancer (MDA), and low-AQP1-expressing SW480. 5HMF, 5NFA, and 5AMF selectively impaired cell motility in the AQP1-enriched cell lines. In contrast, M5NF immobilized all the cancer lines by disrupting actin cytoskeleton. No reduction in cell viability was observed at doses that were effective in blocking motility. These results define furans as a new class of AQP1 ion channel inhibitors for basic research and potential lead compounds for development of therapeutic agents targeting aquaporin channel activity. SIGNIFICANCE STATEMENT: 5-Hydroxymethyl-2-furfural (5HMF), a component of natural medicinal honeys, blocks the ion conductance but not the water flux through human Aquaporin-1 (AQP1) channels and impairs AQP1-dependent cell migration and invasiveness in cancer cell lines. Analyses of 5HMT and structural analogs demonstrate a structure-activity relationship for furan compounds, supported by in silico docking modeling. This work identifies new low-cost pharmacological antagonists for AQP1 available to researchers internationally. Furans merit consideration as a new class of therapeutic agents for controlling cancer metastasis.

Upregulation of adipocyte enhancer-binding protein 1 in endothelial cells promotes tumor angiogenesis in colorectal cancer

Tumor angiogenesis is an important therapeutic target in colorectal cancer (CRC). We aimed to identify novel genes associated with angiogenesis in CRC. Using RNA sequencing analysis in normal and tumor endothelial cells (TECs) isolated from primary CRC tissues, we detected frequent upregulation of adipocyte enhancer‐binding protein 1 (AEBP1) in TECs. Immunohistochemical analysis revealed that AEBP1 is upregulated in TECs and stromal cells in CRC tissues. Quantitative RT‐PCR analysis showed that there is little or no AEBP1 expression in CRC cell lines, but that AEBP1 is well expressed in vascular endothelial cells. Levels of AEBP1 expression in Human umbilical vein endothelial cells (HUVECs) were upregulated by tumor conditioned medium derived from CRC cells or by direct coculture with CRC cells. Knockdown of AEBP1 suppressed proliferation, migration, and in vitro tube formation by HUVECs. In xenograft experiments, AEBP1 knockdown suppressed tumorigenesis and microvessel formation. Depletion of AEBP1 in HUVECs downregulated a series of genes associated with angiogenesis or endothelial function, including aquaporin 1 (AQP1) and periostin (POSTN), suggesting that AEBP1 might promote angiogenesis through regulation of those genes. These results suggest that upregulation of AEBP1 contributes to tumor angiogenesis in CRC, which makes AEBP1 a potentially useful therapeutic target.

Aquaporin-1 plays a key role in erythropoietin-induced endothelial cell migration

Water influx through aquaporin-1 (AQP-1) has been linked to the ability of different cell types to migrate, and therefore plays an important part in processes like metastasis and angiogenesis. Since the erythroid growth factor erythropoietin (Epo) is now recognized as an angiogenesis promoter, we investigated the participation of AQP-1 as a downstream effector of this cytokine in the migration of endothelial cells. Inhibition of AQP-1 with either mercury ions (Hg²⁺) or a specific siRNA led to an impaired migration of EA.hy926 endothelial cells exposed to Epo (wound-healing assays). Epo also induced the expression of AQP-1 at mRNA and protein levels, an effect which was dependent on the influx of extracellular calcium through L-type calcium channels as well as TRPC3 channels. The relationship between Epo and AQP-1 was further confirmed at shorter exposure times, as the cytokine was unable to trigger calcium influxes in cells where AQP-1 had previously been knocked down. Moreover, Epo promoted changes in the subcellular localization of AQP-1 as well as rearrangements in the actin cytoskeleton, which are consistent with a migratory phenotype. Worthy of note, carbamylated erythropoietin (cEpo), the non-erythropoietic and non-promigratory derivative of Epo, was incapable of AQP-1 modulation. The therapeutical implications of aquaporin targeting in angiogenesis-related diseases highlight the importance of the present results in the context of the relationship between AQP-1 and Epo.

Bacopasides I and II Act in Synergy to Inhibit the Growth, Migration and Invasion of Breast Cancer Cell Lines

Bacopaside (bac) I and II are triterpene saponins purified from the medicinal herb Bacopa monnieri. Previously, we showed that bac II reduced endothelial cell migration and tube formation and induced apoptosis in colorectal cancer cell lines. The aim of the current study was to examine the effects of treatment with combined doses of bac I and bac II using four cell lines representative of the breast cancer subtypes: triple negative (MDA-MB-231), estrogen receptor positive (T47D and MCF7) and human epidermal growth factor receptor 2 (HER2) positive (BT-474). Drug treatment outcome measures included cell viability, proliferation, cell cycle, apoptosis, migration, and invasion assays. Relationships were analysed by one- and two-way analysis of variance with Bonferroni post-hoc analysis. Combined doses of bac I and bac II, each below their half maximal inhibitory concentration (IC50), were synergistic and reduced the viability and proliferation of the four breast cancer cell lines. Cell loss occurred at the highest dose combinations and was associated with G2/M arrest and apoptosis. Migration in the scratch wound assay was significantly reduced at apoptosis-inducing combinations, but also at non-cytotoxic combinations, for MDA-MB-231 and T47D (p < 0.0001) and BT-474 (p = 0.0003). Non-cytotoxic combinations also significantly reduced spheroid invasion of MDA-MB-231 cells by up to 97% (p < 0.0001). Combining bac I and II below their IC50 reduced the viability, proliferation, and migration and invasiveness of breast cancer cell lines, suggesting synergy between bac I and II.

Druggable Molecular Targets for the Treatment of Triple Negative Breast Cancer

Breast cancer (BC) is still the most common cancer among women worldwide. Amongst the subtypes of BC, triple negative breast cancer (TNBC) is characterized by deficient expression of estrogen, progesterone, and human epidermal growth factor receptor 2 receptors. These patients are therefore not given the option of targeted therapy and have worse prognosis as a result. Consequently, much research has been devoted to identifying specific molecular targets that can be utilized for targeted cancer therapy, thereby limiting the progression and metastasis of this invasive tumor, and improving patient outcomes. In this review, we have focused on the molecular targets in TNBC, categorizing these into targets within the immune system such as immune checkpoint modulators, intra-nuclear targets, intracellular targets, and cell surface targets. The aim of this review is to introduce and summarize the known targets and drugs under investigation in phase II or III clinical trials, while introducing additional possible targets for future drug development. This review brings a tangible benefit to cancer researchers who seek a comprehensive comparison of TNBC treatment options.

Combined pharmacological administration of AQP1 ion channel blocker AqB011 and water channel blocker Bacopaside II amplifies inhibition of colon cancer cell migration

Aquaporin-1 (AQP1) has been proposed as a dual water and cation channel that when upregulated in cancers enhances cell migration rates; however, the mechanism remains unknown. Previous work identified AqB011 as an inhibitor of the gated human AQP1 cation conductance, and bacopaside II as a blocker of AQP1 water pores. In two colorectal adenocarcinoma cell lines, high levels of AQP1 transcript were confirmed in HT29, and low levels in SW480 cells, by quantitative PCR (polymerase chain reaction). Comparable differences in membrane AQP1 protein levels were demonstrated by immunofluorescence imaging. Migration rates were quantified using circular wound closure assays and live-cell tracking. AqB011 and bacopaside II, applied in combination, produced greater inhibitory effects on cell migration than did either agent alone. The high efficacy of AqB011 alone and in combination with bacopaside II in slowing HT29 cell motility correlated with abundant membrane localization of AQP1 protein. In SW480, neither agent alone was effective in blocking cell motility; however, combined application did cause inhibition of motility, consistent with low levels of membrane AQP1 expression. Bacopaside alone or combined with AqB011 also significantly impaired lamellipodial formation in both cell lines. Knockdown of AQP1 with siRNA (confirmed by quantitative PCR) reduced the effectiveness of the combined inhibitors, confirming AQP1 as a target of action. Invasiveness measured using transwell filters layered with extracellular matrix in both cell lines was inhibited by AqB011, with a greater potency in HT29 than SW480. A side effect of bacopaside II at high doses was a potentiation of invasiveness, that was reversed by AqB011. Results here are the first to demonstrate that combined block of the AQP1 ion channel and water pores is more potent in impairing motility across diverse classes of colon cancer cells than single agents alone.

Stereoselective Anti-Cancer Activities of Ginsenoside Rg3 on Triple Negative Breast Cancer Cell Models

Ginsenoside Rg3 (Rg3) has two epimers, 20(S)-ginsenoside Rg3 (SRg3) and 20(R)-ginsenoside Rg3 (RRg3), and while Rg3 itself has been reported to have anti-cancer properties, few studies have been reported on the anti-cancer effects of the different epimers. The aim was to investigate the stereoselective effects of the Rg3 epimers on triple negative breast cancer (TNBC) cell lines, tested using cell-based assays for proliferation, apoptosis, cell cycle arrest, migration and invasion. Molecular docking showed that Rg3 interacted with the aquaporin 1 (AQP1) water channel (binding score -9.4 kJ mol-1). The Xenopus laevis oocyte expression system was used to study the effect of Rg3 epimers on the AQP1 water permeability. The AQP1 expression in TNBC cell lines was compared with quantitative-polymerase chain reaction (PCR). The results showed that only SRg3 inhibited the AQP1 water flux and inhibited the proliferation of MDA-MB-231 (100 μM), due to cell cycle arrest at G0/G1. SRg3 inhibited the chemoattractant-induced migration of MDA-MB-231. The AQP1 expression in MDA-MB-231 was higher than in HCC1143 or DU4475 cell lines. These results suggest a role for AQP1 in the proliferation and chemoattractant-induced migration of this cell line. Compared to SRg3, RRg3 had more potency and efficacy, inhibiting the migration and invasion of MDA-MB-231. Rg3 has stereoselective anti-cancer effects in the AQP1 high-expressing cell line MDA-MB-231.

Bumetanide-Derived Aquaporin 1 Inhibitors, AqB013 and AqB050 Inhibit Tube Formation of Endothelial Cells through Induction of Apoptosis and Impaired Migration In Vitro

AqB013 and AqB050 compounds inhibit aquaporin 1 (AQP1), a dual water and ion channel implicated in tumour angiogenesis. We tested AqB013 and AqB050 either as monotherapy or in combination on tube formation of murine endothelial cells (2H-11 and 3B-11) and human umbilical vascular endothelial cells (HUVECs). The mechanism underlying their anti-tubulogenic effect was explored by examining cell viability, induction of apoptosis and migration using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, Annexin V/propidium iodide apoptosis assay and scratch wound assay. Tube formation of all the cell lines was inhibited by AqB013, AqB050 and the combination of the two compounds. The inhibition of 2H-11 and 3B-11 was frequently accompanied by impaired migration, whereas that of HUVEC treated with AqB050 and the combination was associated with reduced cell viability due to apoptosis. AqB013 and AqB050 exhibited an anti-tubulogenic effect through inhibition of AQP1-mediated cell migration and induction of apoptosis. Together with previously reported anti-tumour cell effect of AqB013 and AqB050, our findings support further evaluation of these compounds as potential cancer therapeutics.

Aquaporins 1, 3 and 5 in Different Tumors, their Expression, Prognosis Value and Role as New Therapeutic Targets

All different types of metabolism of tumors are dependent on the flow of water molecules through the biological membrane, where fluid transfer interceded by aquaporins (AQPs) are the basis means for water entrance into the cells or outside them. Aquaporins play other roles including cellular migration, cellular expansion and cellular adhesion facilitation. Therefore, regulators of AQPs may be useful anticancer agents. Medline, Scopus, Embase, and Web of Sciences were searched. From among the papers found, 106 were related to the subject. All of the examined cancers in relation to AQP1 included adenoid cystic carcinoma, bladder, breast, cervical, colon, colorectal, hepatocellular, lung, ovarian, plural mesothelioma, prostate, renal cell carcinoma and squamous cell carcinoma. All of the studied cancers in relation with AQP3 included gastric, breast, prostate, lung, pancreas, skin, bladder, squamous cell carcinoma, cervical, adenoid cystic carcinoma, colon, colorectal, ovarian, and hepatocellular cancers and with regard to AQP5 were lung, squamous cell carcinoma, ovarian, adenoid cystic carcinoma, breast, colon, colorectal, hepatic, pancreas, gallbladder, prostate, and gastric cancers. Over or under-expression of AQP1, 3 and is exist in the mentioned cancers across different studies. Over-expression of AQP1, AQP3 and AQP5 is clearly associated with carcinogenesis, metastasis, reduced survival rate, lymph node metastasis, poorer prognosis, and cellular migration. Also, cancer treatments in relation to these markers suggest AQP reduction during the treatment.

Development of a Photoswitchable Lithium-Sensitive Probe to Analyze Nonselective Cation Channel Activity in Migrating Cancer Cells

This is the first work to use a newly designed Li⁺-selective photoswitchable probe Sabrina Heng Lithium (SHL) in living colon cancer cells to noninvasively monitor cation channel activity in real time by the appearance of lithium hot spots detected by confocal microscopy. Punctate Li⁺ hot spots are clustered in the lamellipodial leading edges of HT29 human colon cancer cells and are colocalized with aquaporin-1 (AQP1) channels. AQP1 is a dual water and cyclic-nucleotide-gated cation channel located in lamellipodia and is essential for rapid cell migration in a subset of aggressive cancers. Both the Li⁺ hot spots and cell migration are blocked in HT29 cells by the AQP1 ion channel antagonist AqB011. In contrast, Li⁺ hot spots are not evident in a poorly migrating colon cancer cell line, SW620, which lacks comparable membrane expression of AQP1. Knockdown of AQP1 by RNA interference in HT29 cells significantly impairs Li⁺ hot spot activity. The SHL probe loaded in living cells shows signature chemical properties of ionic selectivity and reversibility. Dynamic properties of the Li⁺ hot spots, turning on and off, are confirmed by time-lapse imaging. SHL is a powerful tool for evaluating cation channel function in living cells in real time, with particular promise for studies of motile cells or interlinked networks not easily analyzed by electrophysiological methods. The ability to reset SHL by photoswitching allows monitoring of dynamic signals over time. Future applications of the Li⁺ probe could include high-throughput optical screening for discovering new classes of channels, or finding new pharmacological modulators for nonselective cation channels.

L-4, a Well-Tolerated and Orally Active Inhibitor of Hedgehog Pathway, Exhibited Potent Anti-tumor Effects Against Medulloblastoma in vitro and in vivo

Inhibition of aberrant Hedgehog (Hh) pathway had been proved to be a promising therapeutic intervention in cancers like basal cell carcinoma (BCC), medulloblastoma (MB), and so on. Two drugs (Vismodegib, Sonidegib) were approved to treat BCC and more inhibitors are in clinical investigation. However, the adverse effects and drug resistance restricted the use of Hh inhibitors. In the present study, 61 synthesized compounds containing central backbone of phthalazine or dimethylpyridazine were screened as candidates of new Hh signaling inhibitors by performing dual luciferase reporter assay. Among the compounds, L-4 exhibited an IC₅₀ value of 2.33 nM in the Shh-Light II assay. L-4 strongly inhibited the Hh pathway in vitro and blocked the Hh pathway by antagonizing the smoothened receptor (Smo). Remarkably, L-4 could significantly suppress the Hh pathway activity provoked by Smo mutant (D473H) which showed strong resistant properties to existing drugs such as Vismodegib. Orally administered L-4 exhibited prominent dose-dependent anti-tumor efficacy in vivo in Ptch+/-; p53-/- MB allograft model. Furthermore, L-4 showed good tolerance in acute toxicity test using ICR mice. These evidences indicated that L-4 was a potent, well-tolerated, orally active inhibitor of Hedgehog pathway, and might be a promising candidate in development of Hh-targeted anti-cancer drugs.

Reduced aquaporin-1 transcript expression in colorectal carcinoma is associated with promoter hypermethylation

Aquaporin-1 (AQP1) is a homo-tetrameric transmembrane protein that facilitates rapid movement of water and ions across cell membranes. The clinical significance of AQP1 expression in colorectal carcinoma (CRC) is controversial. The aim of this study was to investigate the prognostic significance of AQP1 transcript expression and the association between expression and promoter methylation in normal colonic mucosa, CRC tissues and cell lines. Analysis of publicly available datasets from The Cancer Genome Atlas revealed that AQP1 expression was significantly decreased in CRC compared to normal mucosa (12.7 versus 33.3 respectively, P < 0.0001). However, expression increased with advanced disease, being significantly higher in stage IV (17.6) compared to either stage I (11.8, P = 0.0039) or II (10.9; P = 0.0023), and in patients with lymph node metastasis compared to those without (13.9 versus 11.3 respectively, P = 0.0023). Elevated expression was associated with decreased overall survival with univariate (Cox Proportional Hazard Ratio 1.60, 95% confidence interval 1.05-2.42, P = 0.028), but not multivariable analysis when considering the confounders stage and age. Analysis of HumanMethylation450 data demonstrated that AQP1 promoter methylation was significantly increased in CRC compared to normal mucosa. Analysis of CRC tissues and cell lines strongly suggested that methylation was associated with decreased expression. BRAF^V600E mutation alone did not explain the increase in methylation. In conclusion, AQP1 transcript expression was decreased in CRC compared to normal mucosa, and this was associated with AQP1 promoter hypermethylation. AQP1 transcript expression increased with advanced disease but was not an independent prognostic indicator.

Ginsenoside Rg3: Potential Molecular Targets and Therapeutic Indication in Metastatic Breast Cancer

Breast cancer is still one of the most prevalent cancers and a leading cause of cancer death worldwide. The key challenge with cancer treatment is the choice of the best therapeutic agents with the least possible toxicities on the patient. Recently, attention has been drawn to herbal compounds, in particular ginsenosides, extracted from the root of the Ginseng plant. In various studies, significant anti-cancer properties of ginsenosides have been reported in different cancers. The mode of action of ginsenoside Rg3 (Rg3) in in vitro and in vivo breast cancer models and its value as an anti-cancer treatment for breast cancer will be reviewed.

An accurate and cost-effective alternative method for measuring cell migration with the circular wound closure assay

Cell migration is important in many physiological and pathological processes. Mechanisms of two-dimensional cell migration have been investigated most commonly by evaluating rates of cell migration into linearly scratched zones on the surfaces of culture plates. Here, we present a detailed description of a simple adaptation for the well-known and popular wound closure assay, using a circular wound instead of a straight line. This method demonstrates improved precision, reproducibility, and sampling objectivity for measurements of wound sizes as compared with classic scratch assays, enabling more accurate calculations of migration rate. The added benefits of the method are simplicity and low cost as compared with commercially available assays for generating circular wounds.

Preclinical three-dimensional colorectal cancer model: The next generation of in vitro drug efficacy evaluation

Colorectal cancer (CRC), the third most common cancer diagnosed in both men and women in the United States, shows a highly ineffective therapeutic management. In these years neither substantial improvements nor new therapeutic approaches have been provided to patients. Performing the early lead discovery phases of new cancer drugs in cellular models, resembling as far as possible the real in vivo tumor environment, may be more effective in predicting their future success in the later clinical phases. In this review, we critically describe the most representative bioengineered models for anticancer drug screening in CRC from the conventional two-dimensional models to the new-generation three-dimensional scaffold-based ones. The scaffold aims to replace the extracellular matrix, thus influencing the biomechanical, biochemical, and biological properties of cells and tissues. In this scenario, we believe that reconstitution of tumor condition is mandatory for an alternative in vitro methods to study cancer development and therapeutic strategies.

The Purified Extract from the Medicinal Plant Bacopa monnieri, Bacopaside II, Inhibits Growth of Colon Cancer Cells In Vitro by Inducing Cell Cycle Arrest and Apoptosis

Aquaporin-1 (AQP1), a transmembrane pore-forming molecule, facilitates the rapid movement of water and small solutes across cell membranes. We have previously shown that bacopaside II, an extract from the medicinal herb Bacopa monnieri, blocks the AQP1 water channel and impairs migration of cells that express AQP1. The aim of this study was to further elucidate the anti-tumour potential of bacopaside II in colon cancer cells. Expression of AQP1 in HT-29, SW480, SW620 and HCT116 was determined by quantitative PCR and western immunoblot. Cells were treated with bacopaside II, and morphology, growth, autophagy, cell cycle and apoptosis assessed by time-lapse microscopy, crystal violet, acridine orange, propidium iodide (PI) and annexin V/PI staining respectively. AQP1 expression was significantly higher in HT-29 than SW480, SW620 and HCT116. Bacopaside II significantly reduced growth at ≥20 µM for HT-29 and ≥15 µM for SW480, SW620 and HCT116. Inhibition of HT-29 at 20 µM was primarily mediated by G0/G1 cell cycle arrest, and at 30 µM by G2/M arrest and apoptosis. Inhibition of SW480, SW620 and HCT116 at ≥15 µM was mediated by G2/M arrest and apoptosis. These results are the first to show that bacopaside II inhibits colon cancer cell growth by inducing cell cycle arrest and apoptosis.

Mechanisms of Aquaporin-Facilitated Cancer Invasion and Metastasis

Cancer is a leading cause of death worldwide, and its incidence is rising with numbers expected to increase 70% in the next two decades. The fact that current mainline treatments for cancer patients are accompanied by debilitating side effects prompts a growing demand for new therapies that not only inhibit growth and proliferation of cancer cells, but also control invasion and metastasis. One class of targets gaining international attention is the aquaporins, a family of membrane-spanning water channels with diverse physiological functions and extensive tissue-specific distributions in humans. Aquaporins−1,−2,−3,−4,−5,−8, and−9 have been linked to roles in cancer invasion, and metastasis, but their mechanisms of action remain to be fully defined. Aquaporins are implicated in the metastatic cascade in processes of angiogenesis, cellular dissociation, migration, and invasion. Cancer invasion and metastasis are proposed to be potentiated by aquaporins in boosting tumor angiogenesis, enhancing cell volume regulation, regulating cell-cell and cell-matrix adhesions, interacting with actin cytoskeleton, regulating proteases and extracellular-matrix degrading molecules, contributing to the regulation of epithelial-mesenchymal transitions, and interacting with signaling pathways enabling motility and invasion. Pharmacological modulators of aquaporin channels are being identified and tested for therapeutic potential, including compounds derived from loop diuretics, metal-containing organic compounds, plant natural products, and other small molecules. Further studies on aquaporin-dependent functions in cancer metastasis are needed to define the differential contributions of different classes of aquaporin channels to regulation of fluid balance, cell volume, small solute transport, signal transduction, their possible relevance as rate limiting steps, and potential values as therapeutic targets for invasion and metastasis.

Aquaporin 1 expression is associated with response to adjuvant chemotherapy in stage II and III colorectal cancer

Aquaporin 1 (AQP1), which functions as a water transporter, is associated with cancer cell proliferation, invasion, metastasis and angiogenesis in numerous types of solid cancer, including colorectal cancer (CRC). The focus of the present study was to address the potential clinical use of AQP1 expression in CRC as a prognostic and predictive biomarker for disease recurrence and therapeutic outcomes. The current study investigated the expression of AQP1 in surgically resected specimens from 268 patients with stage 0-IV CRC. AQP1 expression was positive in 112 (41.8%) patients, and was significantly associated with left-sided tumors (P<0.01) and with aggressive tumor phenotypes, including depth of invasion (P=0.03), lymph node metastasis (P=0.03), lymphatic invasion (P<0.01) and venous invasion (P<0.01). However, AQP1 expression had no significant prognostic effect on disease-free survival (DFS) in patients with stage II and III CRC following curative surgery. In 84 stage II and III patients who were administered 5-fluorouracil-based adjuvant chemotherapy, positive AQP1 expression was associated with an increased DFS rate compared with that of AQP1-negative patients (P=0.05). Additionally, these results identified that receiving adjuvant chemotherapy was not beneficial to patients with AQP1-negative tumors. This suggests that the expression of AQP1 may be a candidate biomarker predictive of response to 5-fluorouracil-based adjuvant chemotherapy following surgery in patients with stage II and III CRC.