Aquaporins in Cancer Biology

Deciphering Glioblastoma: Fundamental and Novel Insights into the Biology and Therapeutic Strategies of Gliomas

Gliomas constitute a diverse and complex array of tumors within the central nervous system (CNS), characterized by a wide range of prognostic outcomes and responses to therapeutic interventions. This literature review endeavors to conduct a thorough investigation of gliomas, with a particular emphasis on glioblastoma (GBM), beginning with their classification and epidemiological characteristics, evaluating their relative importance within the CNS tumor spectrum. We examine the immunological context of gliomas, unveiling the intricate immune environment and its ramifications for disease progression and therapeutic strategies. Moreover, we accentuate critical developments in understanding tumor behavior, focusing on recent research breakthroughs in treatment responses and the elucidation of cellular signaling pathways. Analyzing the most novel transcriptomic studies, we investigate the variations in gene expression patterns in glioma cells, assessing the prognostic and therapeutic implications of these genetic alterations. Furthermore, the role of epigenetic modifications in the pathogenesis of gliomas is underscored, suggesting that such changes are fundamental to tumor evolution and possible therapeutic advancements. In the end, this comparative oncological analysis situates GBM within the wider context of neoplasms, delineating both distinct and shared characteristics with other types of tumors.

Data-driven energy landscape reveals critical genes in cancer progression

The evolution of cancer is a complex process characterized by stable states and transitions among them. Studying the dynamic evolution of cancer and revealing the mechanisms of cancer progression based on experimental data is an important topic. In this study, we aim to employ a data-driven energy landscape approach to analyze the dynamic evolution of cancer. We take Kidney renal clear cell carcinoma (KIRC) as an example. From the energy landscape, we introduce two quantitative indicators (transition probability and barrier height) to study critical shifts in KIRC cancer evolution, including cancer onset and progression, and identify critical genes involved in these transitions. Our results successfully identify crucial genes that either promote or inhibit these transition processes in KIRC. We also conduct a comprehensive biological function analysis on these genes, validating the accuracy and reliability of our predictions. This work has implications for discovering new biomarkers, drug targets, and cancer treatment strategies in KIRC.

Homeostatic status of thyroid hormones and brain water movement as determinant factors in biology of cerebral gliomas: a pilot study using a bioinformatics approach

Introduction

The expression and localization of the water channel transporters, aquaporins (AQPs), in the brain are substantially modified in gliomas during tumorigenesis, cell migration, edema formation, and resolution. We hypothesized that the molecular changes associated with AQP1 and AQP4 in the brain may potentially be anticancer therapeutic targets. To test this hypothesis, a bioinformatics analysis of publicly available data from international consortia was performed.

Methods

We used RNA-seq as an experimental strategy and identified the number of differential AQP1 and AQP4 transcript expressions in glioma tissue compared to normal brain tissue.

Results

AQPs genes are overexpressed in patients with glioma. Among the glioma subtypes, AQP1 and AQP4 were overexpressed in astrocytoma (low-grade glioma) and classical (high-grade glioma). Overall survival analysis demonstrated that both AQP genes can be used as prognostic factors for patients with low-grade glioma. Additionally, we observed a correlation between the expression of genes involved in the tyrosine and thyroid hormone pathways and AQPs, namely: PNMT, ALDH1A3, AOC2, HGDATP1B1, ADCY5, PLCB4, ITPR1, ATP1A3, LRP2, HDAC1, MED24, MTOR, and ACTB1 (Spearman's coefficient = geq 0.20 and p-value = ≤ 0.05).

Conclusion

Our findings indicate that the thyroid hormone pathways and AQPs 1 and 4 are potential targets for new anti-tumor drugs and therapeutic biomarkers for malignant gliomas.

Uncovering the role of aquaporin and chromobox family members as potential biomarkers in head and neck squamous cell carcinoma via integrative multiomics and in silico approach

Head and neck squamous cell carcinoma (HNSC) is a diverse group of tumors arising from oral cavity, oropharynx, larynx, and hypopharynx squamous epithelium, posing significant morbidity. Aquaporins (AQPs) are membrane proteins forming water channels, some associated with carcinomas. Chromobox (CBX) family is known to modulate physiological and oncological processes. In our study, we analyzed AQPs and CBXs having significant expression followed by their prognostic and mutational assessment. Next, we performed enrichment and tumor infiltration analysis followed by HPA validation. Lastly, we established a 3-node miRNA-TF-mRNA regulatory network and performed protein-protein docking of the highest-degree subnetwork motif between TF and mRNA. Significant upregulation of CBX3/2 and downregulation of AQP3/5/7 correlated with poor overall survival (OS) in HNSC patients. The most significant pathway, GO-BP, GO-MF, and GO-CC terms associated with AQP3 and CBX3 were passive transport by aquaporins, response to vitamin, glycerol channel activity, and condensed chromosome, centromeric region. AQP3 negatively correlated with [Formula: see text] T cells, positively with [Formula: see text] T cells and B cells, and negatively with tumor purity, whereas CBX3 positively correlated with [Formula: see text] T cells, negatively with [Formula: see text] T cells and B cells, and positively with tumor purity. Three-node miRNA-TF-mRNA regulatory network revealed a highest-degree subnetwork motif comprising one TF (SMAD3), one miRNA (miR-423-5p), and one mRNA (AQP3). Protein-protein interaction studies suggested a direct interaction between AQP3 and Smad3 proteins. We concluded that AQP3 and CBX3 hold potential as treatment strategies and individual prognostic biomarkers, while further protein-protein interaction studies of AQP3 could offer insights into its interactions with Smad3 proteins.

Blockage of aquaporin-3 peroxiporin activity by organogold compounds affects melanoma cell adhesion, proliferation and migration

Aquaporin-3 (AQP3) is a membrane channel with dual aquaglyceroporin/peroxiporin activity, facilitating the diffusion of water, glycerol and H2 O2 across cell membranes. AQP3 shows aberrant expression in melanoma and its role in cell adhesion, migration and proliferation is well described. Gold compounds were shown to modulate AQP3 activity with reduced associated toxicity, making them promising molecules for cancer therapy. In this study, we validated the phenotype resulting from AQP3-silencing of two melanoma cell lines, MNT-1 and A375, which resulted in decreased H2 O2 permeability. Subsequently, the AQP3 inhibitory effect of a new series of organogold compounds derived from Auphen, a potent AQP3 inhibitor, was first evaluated in red blood cells (RBCs) that highly express AQP3, and then in HEK-293T cells with AQP3 overexpression to ascertain the compounds' specificity. The first screening in RBCs unveiled two organogold compounds as promising blockers of AQP3 permeability. Moderate reduction of glycerol permeability but drastic inhibition of H2 O2 permeability was detected for some of the gold derivatives in both AQP3-overexpressing cells and human melanoma cell lines. Additionally, all compounds were effective in impairing cell adhesion, proliferation and migration, although in a cell type-dependent manner. In conclusion, our data show that AQP3 peroxiporin activity is crucial for melanoma progression and highlight organogold compounds as promising AQP3 inhibitors with implications in melanoma cell adhesion, proliferation and migration, unveiling their potential as anticancer drugs against AQP3-overexpressing tumours. KEY POINTS: AQP3 affects cellular redox balance. Gold compounds inhibit AQP3 permeability in melanoma cells. AQP3 is involved in cell adhesion, proliferation and migration of melanoma. Blockage of AQP3 peroxiporin activity impairs melanoma cell migration. Gold compounds are potential anticancer drug leads for AQP3-overexpressing cancers.

Cranberry Proanthocyanidins Mitigate Reflux-Induced Transporter Dysregulation in an Esophageal Adenocarcinoma Model

We recently reported that cranberry proanthocyanidins (C-PACs) inhibit esophageal adenocarcinoma (EAC) by 83% through reversing reflux-induced bacterial, inflammatory and immune-implicated proteins and genes as well as reducing esophageal bile acids, which drive EAC progression. This study investigated whether C-PACs' mitigation of bile reflux-induced transporter dysregulation mechanistically contributes to EAC prevention. RNA was isolated from water-, C-PAC- and reflux-exposed rat esophagi with and without C-PAC treatment. Differential gene expression was determined by means of RNA sequencing and RT-PCR, followed by protein assessments. The literature, coupled with the publicly available Gene Expression Omnibus dataset GSE26886, was used to assess transporter expression levels in normal and EAC patient biopsies for translational relevance. Significant changes in ATP-binding cassette (ABC) transporters implicated in therapeutic resistance in humans (i.e., Abcb1, Abcb4, Abcc1, Abcc3, Abcc4, Abcc6 and Abcc10) and the transport of drugs, xenobiotics, lipids, and bile were altered in the reflux model with C-PACs' mitigating changes. Additionally, C-PACs restored reflux-induced changes in solute carrier (SLC), aquaporin, proton and cation transporters (i.e., Slc2a1, Slc7a11, Slc9a1, Slco2a1 and Atp6v0c). This research supports the suggestion that transporters merit investigation not only for their roles in metabolism and therapeutic resistance, but as targets for cancer prevention and targeting preventive agents in combination with chemotherapeutics.

Effects of cold atmospheric-pressure plasma in combination with doxorubicin drug against breast cancer cells in vitro and invivo

Cold atmospheric plasma (CAP) has been suggested for medical applications that can be applied indirectly through plasma-activated medium (PAM) and recently it has been introduced as an innovative therapeutic approach for all cancer types. Studies have exhibited that ROS/RNS are key factors in CAP-dependent apoptosis; nevertheless, ROS/RNS stability are weak. Combination therapy is considered an effective strategy to overcome these problems. In the present research, we revealed that the combination of CAP and doxorubicin (DOX) significantly induces the apoptosis of breast cancer cells both in vitro and in vivo. Our results indicated that both Ar and He/O2 CAP treatment as well as DOX drug alone reduced cell growth. CAP/PAM treatment in combination with DOX induced apoptosis in MCF-7 breast cancer cells and 4T1-implanted BALB/c mice, resulting in a significant increase in antitumor activity. The apoptotic effects of CAP-DOX on MCF-7 cells were inferred from altered expression of BAX and cleaved-caspase-3 which mechanistically take place through the mitochondrial pathway mediated by Bcl-2 family members. Besides, the BAX/BCL-2 ratio is significantly higher in the simultaneous treatment of CAP and DOX. This ratio was equal to 2.82 ± 0.24, 2.54 ± 0.30, and 11.27 ± 0.31 for treatment with DOX, He/O2 plasma, and combination treatment, respectively. Additionally, the tumor growth rate of He/O2-PAM + DOX and Ar-PAM + DOX treatments was significantly inhibited by PAM-injection, and the tumor growth rate of PAM alone or DOX alone was slightly reduced. It can be concluded that the effect of PAM + DOX may increase the anticancer activity and decrease the dose required for the chemotherapeutic treatment.

Aquaporin 9 causes recurrent spontaneous abortion by inhibiting trophoblast cell epithelial-mesenchymal transformation and invasion through the PI3K/AKT pathway†

BACKGROUND

Invasion of the endometrium by trophoblast cells is a key event during pregnancy, although the underlying mechanism remains unclear. Aquaporin 9 (AQP 9) is expressed in many eukaryotes and is associated with cell invasion. The objective of this study was to evaluate the significance of AQP9 in recurrent spontaneous abortion.

METHODS

We screened the GSE22490 dataset and further differentiated aquaporin 9 expression in villi. AQP9 was evaluated as one of the key factors in abortion by injecting AQP9 overexpressed plasmid into the uterus of CD1 mice. Trophoblast cells were transfected with AQP9-overexpressing plasmid or siAQP9 to measure cell proliferation, migration, invasion, and apoptosis. Western blot was used to measure changes in the expression of invasion, epithelial-mesenchymal transformation process, and PI3K/AKT pathway. Finally, the role of AQP9 in PI3K/AKT signaling pathway was determined using the PI3K/AKT inhibitor, LY294002, and activator, 740Y-P.

RESULTS

AQP9 is highly expressed in recurrent spontaneous abortion villus. Intrauterine injections of AQP9-overexpressing plasmid into CD1 mice resulted in atrophy and blackness of the gestational sac and increased the absorption rate, it is the causative factor of abortion. AQP9 upregulation inhibited the proliferation, invasion, migration, and epithelial-mesenchymal transformation process in vitro of trophoblast cells and increased cell apoptosis. The opposite result was observed after silencing AQP9. AQP9 overexpression also inhibited the PI3K/AKT pathway. LY294002 and 740Y-P partially recovered AQP9-induced trophoblast invasion and migration via the PI3K/AKT pathway.

CONCLUSIONS

AQP9 reduces the invasive ability of trophoblast cells by regulating PI3K/AKT signaling pathway, participating in recurrent spontaneous abortion.

Hepatocellular Carcinoma: Up-regulated Circular RNAs Which Mediate Efficacy in Preclinical In Vivo Models

Hepatocellular carcinoma (HCC) ranges as number two with respect to the incidence of tumors and is associated with a dismal prognosis. The therapeutic efficacy of approved multi-tyrosine kinase inhibitors and checkpoint inhibitors is modest. Therefore, the identification of new therapeutic targets and entities is of paramount importance. We searched the literature for up-regulated circular RNAs (circRNAs) which mediate efficacy in preclinical in vivo models of HCC. Our search resulted in 14 circRNAs which up-regulate plasma membrane transmembrane receptors, while 5 circRNAs induced secreted proteins. Two circRNAs facilitated replication of Hepatitis B or C viruses. Three circRNAs up-regulated high mobility group proteins. Six circRNAs regulated components of the ubiquitin system. Seven circRNAs induced GTPases of the family of ras-associated binding proteins (RABs). Three circRNAs induced redox-related proteins, eight of them up-regulated metabolic enzymes and nine circRNAs induced signaling-related proteins. The identified circRNAs up-regulate the corresponding targets by sponging microRNAs. Identified circRNAs and their targets have to be validated by standard criteria of preclinical drug development. Identified targets can potentially be inhibited by small molecules or antibody-based moieties and circRNAs can be inhibited by small-interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs) for therapeutic purposes.

Identification of key genes and validation of key gene aquaporin 1 on Wilms' tumor metastasis

Background

Wilms' tumor (WT) is one of the most common solid tumors in children with unsatisfactory prognosis, but few molecular prognostic markers have been discovered for it. Many genes are associated with the occurrence and prognosis of WT. This study aimed to explore the key genes and potential molecular mechanisms through bioinformatics and to verify the effects of aquaporin 1 (AQP1) on WT metastasis.

Methods

Differentially expressed genes (DEGs) were generated from WT gene expression data sets from the Gene Expression Omnibus (GEO) database. Gene functional enrichment analysis was carried out with the Database for Annotation, Visualization and Integrated Discovery (DAVID). A protein-protein interaction network (PPI) was constructed and visualized by the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database and Cytoscape software. Minimal Common Oncology Data Elements (MCODE) was used to detect the important modules in the PPI network, and the important nodes (genes) in the PPI module were sorted by CytoHubba. RT-qPCR was performed to validate the expression of the key genes in WT. Wound healing and Transwell assays were used to detect the cell migration and invasion abilities of AQP1-overexpressing cells. Phalloidin-iFlour 488 was used to stain the cytoskeleton to observe how AQP1 overexpression affects cytoskeletal microfilament structure.

Results

A total of 73 co-expressed DEGs were chosen for further investigation. The importance of homeostasis and transmembrane transport of ions and water were highlighted by functional analysis. Gene regulatory network and PPI network were predicted. MCODE plug identified two important modules. Finally, top five key genes were identified using CytoHubba, including Renin (REN), nephrosis 2 (NPHS2), Solute Carrier Family 12 Member 3 (SLC12A3), Solute Carrier Family 12 Member 1 (SLC12A1) and AQP1. The five key genes were mainly enriched in cell volume and ion homeostasis. RT-qPCR confirmed the expression of the five key genes in WT. AQP1 was validated to be expressed at significantly lower levels in WT than in normal tissue. AQP1 overexpression significantly reduced the migratory and invasive capacity of Wit-49 cells, as evidenced by reducing the scratch healing rate and the number of perforated control cells by Wit-49 cells. AQP1 overexpression also reduced the expression of biomarkers of epithelial-mesenchymal transformation, decreased levels of vimentin and N-cadherin and increased expression of E-cadherin, resulting in decreased formation of conspicuous lamellipodial protrusions, characteristic of diminished WT cell invasion and migration.

Conclusion

Our study reveals the key genes of WT. These key genes may provide novel insight for the mechanism and diagnosis of WT. AQP1 overexpression inhibited invasion, migration, EMT, and cytoskeletal rearrangement of WT cells, indicating that AQP1 plays a role in the pathogenesis of WT.

Short-term topiramate treatment prevents radiation-induced cytotoxic edema in preclinical models of breast-cancer brain metastasis

BACKGROUND

Brain edema is a common complication of brain metastases (BM) and associated treatment. The extent to which cytotoxic edema, the first step in the sequence that leads to ionic edema, vasogenic edema, and brain swelling, contributes to radiation-induced brain edema during BM remains unknown. This study aimed to determine whether radiation-associated treatment of BM induces cytotoxic edema and the consequences of blocking the edema in preclinical models of breast-cancer brain metastases (BCBM).

METHODS

Using in vitro and in vivo models, we measured astrocytic swelling, trans-electric resistance (TEER), and aquaporin 4 (AQP4) expression following radiation. Genetic and pharmacological inhibition of AQP4 in astrocytes and cancer cells was used to assess the role of AQP4 in astrocytic swelling and brain water intake. An anti-epileptic drug that blocks AQP4 function (topiramate) was used to prevent cytotoxic edema in models of BM.

RESULTS

Radiation-induced astrocytic swelling and transient upregulation of AQP4 occurred within the first 24 hours following radiation. Topiramate decreased radiation-induced astrocytic swelling and loss of TEER in astrocytes in vitro, and acute short-term treatment (but not continuous administration), prevented radiation-induced increase in brain water content without pro-tumorigenic effects in multiple preclinical models of BCBM. AQP4 was expressed in clinical BM and breast-cancer cell lines, but AQP4 targeting had limited direct pro-tumorigenic or radioprotective effects in cancer cells that could impact its clinical translation.

CONCLUSIONS

Patients with BM could find additional benefits from acute and temporary preventive treatment of radiation-induced cytotoxic edema using anti-epileptic drugs able to block AQP4 function.

Insights into the Function of Aquaporins in Gastrointestinal Fluid Absorption and Secretion in Health and Disease

Aquaporins (AQPs), transmembrane proteins permeable to water, are involved in gastrointestinal secretion. The secretory products of the glands are delivered either to some organ cavities for exocrine glands or to the bloodstream for endocrine glands. The main secretory glands being part of the gastrointestinal system are salivary glands, gastric glands, duodenal Brunner's gland, liver, bile ducts, gallbladder, intestinal goblet cells, exocrine and endocrine pancreas. Due to their expression in gastrointestinal exocrine and endocrine glands, AQPs fulfill important roles in the secretion of various fluids involved in food handling. This review summarizes the contribution of AQPs in physiological and pathophysiological stages related to gastrointestinal secretion.

Aquaporins Transcripts with Potential Prognostic Value in Pancreatic Cancer

Pancreatic cancer is anticipated to be the second leading cause of cancer-related death by 2030. Aquaporins (AQPs), a family of water channel proteins, have been linked to carcinogenesis. The aim of this study was to determine AQP gene expression in pancreatic cancer tissues and to validate aquaporins as possible diagnosis and/or prognosis genes. The relative gene expression levels of AQP1, AQP3, AQP5, and AQP9 were analyzed using real-time quantitative PCR (RT-qPCR) in 24 paired pancreatic tumors and adjacent healthy tissues according to variables such as age, gender, and tumor invasiveness and aggressiveness. AQPs transcripts were detected in both healthy and tumor tissues. While AQP1 was downregulated in the tumor samples, AQP3 was particularly overexpressed in low-grade invasive tumors. Interestingly, most of the strong positive Pearson correlation coefficients found between AQPs in healthy tissues were lost when analyzing the tumor tissues, suggesting disruption of the coordinated AQP-gene expression in pancreatic cancer.

Aquaporin 1 is a prognostic marker and inhibits tumour progression through downregulation of Snail expression in intrahepatic cholangiocarcinoma

BACKGROUND

Recently, some studies have suggested a link between AQP1 and cancer progression.

AIMS

The aim of the present study was to investigate the influence of AQP1 on the clinicopathology and prognosis of intrahepatic cholangiocarcinoma (ICC) patients.

METHODS

We retrospectively detected the expression of AQP1 protein in 307 patients with ICC who underwent partial hepatectomy. Western blot analysis was used to detect AQP1 protein levels in stable AQP1 overexpression and knockdown cell lines. The influence of AQP1 on the invasion and metastasis ability of ICC cells was assessed by wound-healing and Transwell assays in vitro as well as by a splenic liver metastasis model in vivo.

RESULTS

Positive membranous AQP1 expression was identified in 34.2% (105/307) of the ICC specimens. Survival data revealed that positive AQP1 expression was significantly associated with favourable disease-free survival (DFS) and overall survival (OS) (p = 0.0290 and p = 0003, respectively). Moreover, high AQP1 expression inhibited the invasion and migration of ICC cells in vitro as well as inhibited liver metastasis in nude mice. Mechanistically, high AQP1 expression in ICC cells increased the levels of E-cadherin but decreased the levels of the Snail transcription factor.

CONCLUSIONS

AQP1 expression is associated with a favourable prognosis in ICC patients. AQP1 inhibits ICC cell invasion, metastasis, and epithelial-mesenchymal transition (EMT) through downregulation of Snail expression.

PAI1 inhibits the pathogenesis of primary focal hyperhidrosis by targeting CHRNA1

BACKGROUND

Primary focal hyperhidrosis (PFH) may be attributed to the up-regulation of the cholinergic receptor nicotinic alpha 1 subunit (CHRNA1) in eccrine glands. Plasminogen activator inhibitor-1 (PAI1, encoded by SERPINE1) is reported to inhibit the expression of CHRNA1, while the role of PAI1 in hyperhidrosis is unknown.

METHODS

Serpine1 KO mice, Serpine1-Tg mice, and wild type BALB/c mice were intraperitoneally injected with pilocarpine hydrochloride to induce PFH. Cisatracurium (CIS, antagonist of CHRNA1) or PAI-039 (small-molecule inhibitor of PAI1) was pre-administrated before the induction of hyperhidrosis. On the other hand, Chrna1-expressing AAV was constructed and administered to Serpine1-Tg mice with hydrochloride stimulation. Hydrochloride-related biomarkers, such as acetylcholine (ACH) in the serum, calcium voltage-gated channel subunit alpha1 C (CACNA1C), and aquaporin 5 (AQP5) in sweat glands of mice were assayed with ELISA, RT-PCR, and Western blot.

RESULTS

The administration of PAI-039 or Pai1 knock-out increased Chrna1 expression, sweat secretion, and hydrochloride-related biomarkers (ACH, CACNA1C, and AQP5) expression. On the other hand, CIS administration diminished the strengthened hyperhidrosis phenotype induced by Pai1 knock-out with decreased sweat gland secretion.

CONCLUSION

PAI1 inhibits CHRNA1-mediated hydrochloride-induced hyperhidrosis, with decreased sweat gland secretion and diminished ACH, AQP5, and CACNA1C expression. These results indicate the potential to utilize PAI1 to alleviate PFH.

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.

Short-term Topiramate treatment prevents radiation-induced cytotoxic edema in preclinical models of breast-cancer brain metastasis

Background

Brain edema is a common complication of brain metastases (BM) and associated treatment. The extent to which cytotoxic edema, the first step in the sequence that leads to ionic edema, vasogenic edema and brain swelling, contributes to radiation-induced brain edema during BM remains unknown. This study aimed to determine whether radiation-associated treatment of BM induces cytotoxic edema and the consequences of blocking the edema in pre-clinical models of breast cancer brain metastases (BCBM).

Methods

Using in vitro and in vivo models, we measured astrocytic swelling, trans-electric resistance (TEER) and aquaporin 4 (AQP4) expression following radiation. Genetic and pharmacological inhibition of AQP4 in astrocytes and cancer cells was used to assess the role of AQP4 in astrocytic swelling and brain water intake. An anti-epileptic drug that blocks AQP4 function (topiramate) was used to prevent cytotoxic edema in models of BM.

Results

Radiation-induced astrocytic swelling and transient upregulation of AQP4 within the first 24 hours following radiation. Topiramate decreased radiation-induced astrocytic swelling, loss of TEER in astrocytes in vitro , and acute short term treatment (but not continuous administration), prevented radiation-induced increase in brain water content without pro-tumorigenic effects in multiple pre-clinical models of BCBM. AQP4 was expressed in clinical BM and breast cancer cell lines, but AQP4 targeting had limited direct pro-tumorigenic or radioprotective effects in cancer cells that could impact its clinical translation.

Conclusions

Patients with BM could find additional benefits from acute and temporary preventive treatment of radiation-induced cytotoxic edema using anti-epileptic drugs able to block AQP4 function.

Key points

Radiation induces cytotoxic edema via acute dysregulation of AQP4 in astrocytes in preclinical models of BM. Pharmacologic blockage of AQP4 function prevents water intake, astrocytic swelling and restores TEER in vitro. Pre-treatment with single-dose Topiramate prevents brain radiation-induced brain edema without direct tumor effects in pre-clinical models of BCBM.

IMPORTANCE OF THE STUDY

In this study we describe a novel role for astrocytic swelling and cytotoxic edema in the progression of radiation-induced brain edema during BM treatment. While radiation-induced edema has been fully attributed to the disruption of the blood-brain barrier (BBB) and ensuing vasogenic effects, our results suggest that cytotoxic edema affecting astrocytes in the acute setting plays an important role in the progression of brain edema during BM standard of care. Current standard of care for brain edema involves pre-treatment with steroids and the use of bevacizumab only after clinically significant edema develops. Both interventions are presumed to target vasogenic edema. This study suggests that patients with BM could find additional benefits from acute and temporary preventive treatment of radiation-induced cytotoxic edema using an already FDA-approved anti-epileptic drug. Such early prevention strategy can be easily clinically implemented with the goal of minimizing treatment-related toxicities.

The Role of Aquaporin 5 (AQP5) in Lung Adenocarcinoma: A Review Article

Aquaporins (AQPs) are selective, transmembrane proteins, which are primarily responsible for the transport of water and small molecules. They have been demonstrated to play a key role in the development and progression of cancer. Lung adenocarcinoma is the most common primary lung cancer diagnosed in patients in Europe and the USA. The research done so far has provided firm evidence that some AQPs can be biomarkers for various diseases. The objective of this review article is to present a potential role of AQP5 in the development of lung adenocarcinoma. Original papers discussing the involvement of AQP5 in carcinogenesis and containing relevant clinical data were identified. In order to analyze the research material in accordance with PRISMA guidelines, a systematic search of the ScienceDirect, Web of Science, and Pubmed databases was conducted. Out of the total number of 199 papers identified, 14 original articles were subject to analysis. This article presents the pathophysiological role of AQP5 in the biology of lung adenocarcinoma as well as its prognostic value. The analysis substantiates the conclusion that the prognostic value of AQP5 in lung cancer requires further research. Another aim of this paper is to disseminate knowledge about AQPs among clinicians.

Ablation of AQP5 gene in mice leads to olfactory dysfunction caused by hyposecretion of Bowman's gland

Smell detection depends on nasal airflow, which can make absorption of odors to the olfactory epithelium by diffusion through the mucus layer. The odors then act on the chemo-sensitive epithelium of olfactory sensory neurons (OSNs). Therefore, any pathological changes in the olfactory area, for instance, dry nose caused by Sjögren's Syndrome (SS) may interfere with olfactory function. SS is an autoimmune disease in which aquaporin (AQP) 5 autoantibodies have been detected in the serum. However, the expression of AQP5 in olfactory mucosa and its function in olfaction is still unknown. Based on the study of the expression characteristics of AQP5 protein in the nasal mucosa, the olfaction dysfunction in AQP5 knockout (KO) mice was found by olfactory behavior analysis, which was accompanied by reduced secretion volume of Bowman's gland by using in vitro secretion measure system, and the change of acid mucin in nasal mucus layer was identified. By excluding the possibility that olfactory disturbance was caused by changes in OSNs, the result indicated that AQP5 contributes to olfactory functions by regulating the volume and composition of OE mucus layer, which is the medium for the dissolution of odor molecules. Our results indicate that AQP5 can affect the olfactory functions by regulating the water supply of BGs and the mucus layer upper the OE that can explain the olfactory loss in the patients of SS, and AQP5 KO mice might be used as an ideal model to study the olfactory dysfunction.

Screening of possible biomarkers and therapeutic targets in kidney renal clear cell carcinoma: Evidence from bioinformatic analysis

Renal cell carcinoma (RCC), as one of the most common urological malignancies, has many histologic and molecular subtypes, among which clear cell renal cell carcinoma (ccRCC) is one of the most common causes of tumor-related deaths. However, the molecular mechanism of ccRCC remains unclear. In order to identify the candidate genes that may exist in the occurrence and development of ccRCC, microarray datasets GSE6344, GSE16441, GSE36895, GSE53757 and GSE76351 had been downloaded from Gene Expression Omnibus (GEO) database. Apart from that, the differentially expressed genes (DEGs) were screened through Bioinformatics & Evolutionary Genomics. In addition, the protein-protein interaction network (PPI) was constructed, and the module analysis was performed using STRING and Cytoscape. By virtue of DAVID online database, GO/KEGG enrichment analysis of DEGs was performed. Consequently, a total of 118 DEGs were screened, including 24 up-regulated genes and 94 down-regulated genes. The plug-in MCODE of Cytoscape was adopted to analyze the most significant modules of DEGs. What’s more, the genes with degree greater than 10 in DEGs were selected as the hub genes. The overall survival (OS) and disease progression free survival (DFS) of 9 hub genes were analyzed through GEPIA2 online platform. As shown by the survival analysis, SLC34A1, SLC12A3, SLC12A1, PLG, and ENO2 were closely related to the OS of ccRCC, whereas SLC34A1 and LOX were closely related to DFS. Among 11 SLC members, 6 SLC members were highly expressed in non-cancerous tissues (SLC5A2, SLC12A1, SLC12A3, SLC34A1, SLC34A2, SLC34A3). Besides, SLC12A5 and SLC12A7 were highly expressed in ccRCC. Furthermore, SLC12A1-A7, SLC34A1 and SLC34A3 were closely related to OS, whereas SLC12A2/A4/A6/A7 and SLC34A1/A3 were closely related to DFS. In addition, 5 algorithms were used to analyze hub genes, the overlapping genes were AQP2 and KCNJ1. To sum up, hub gene can help us understand the molecular mechanism of the occurrence and development of ccRCC, thereby providing a theoretical basis for the diagnosis and targeted therapy of ccRCC.

Physiological Cooperation between Aquaporin 5 and TRPV4

Aquaporins—among them, AQP5—are responsible for transporting water across biological membranes, which is an important process in all living organisms. The transient receptor potential channel 4 (TRPV4) is a cation channel that is mostly calcium-permeable and can also be activated by osmotic stimuli. It plays a role in a number of different functions in the body, e.g., the development of bones and cartilage, and it is involved in the body’s osmoregulation, the generation of certain types of sensation (pain), and apoptosis. Our earlier studies on the uterus and the literature data aroused our interest in the physiological role of the cooperation of AQP5 and TRPV4. In this review, we focus on the co-expression and cooperation of AQP5 and TRPV4 in the lung, salivary glands, uterus, adipose tissues, and lens. Understanding the cooperation between AQP5 and TRPV4 may contribute to the development of new drug candidates and the therapy of several disorders (e.g., preterm birth, cataract, ischemia/reperfusion-induced edema, exercise- or cold-induced asthma).

A Comprehensive Prognostic Analysis of Tumor-Related Blood Group Antigens in Pan-Cancers Suggests That SEMA7A as a Novel Biomarker in Kidney Renal Clear Cell Carcinoma

Blood group antigen is a class of heritable antigenic substances present on the erythrocyte membrane. However, the role of blood group antigens in cancer prognosis is still largely unclear. In this study, we investigated the expression of 33 blood group antigen genes and their association with the prognosis of 30 types of cancers in 31,870 tumor tissue samples. Our results revealed that blood group antigens are abnormally expressed in a variety of cancers. The high expression of these antigen genes was mainly related to the activation of the epithelial-mesenchymal transition (EMT) pathway. High expression of seven antigen genes, i.e., FUT7, AQP1, P1, C4A, AQP3, KEL and DARC, were significantly associated with good OS (Overall Survival) in six types of cancers, while ten genes, i.e., AQP1, P1, C4A, AQP3, BSG, CD44, CD151, LU, FUT2, and SEMA7A, were associated with poor OS in three types of cancers. Kidney renal clear cell carcinoma (KIRC) is associated with the largest number (14 genes) of prognostic antigen genes, i.e., CD44, CD151, SEMA7A, FUT7, CR1, AQP1, GYPA, FUT3, FUT6, FUT1, SLC14A1, ERMAP, C4A, and B3GALT3. High expression of SEMA7A gene was significantly correlated with a poor prognosis of KIRC in this analysis but has not been reported previously. SEMA7A might be a putative biomarker for poor prognosis in KIRC. In conclusion, our analysis indicates that blood group antigens may play functional important roles in tumorigenesis, progression, and especially prognosis. These results provide data to support prognostic marker development and future clinical management.