AQP1

Gene Summary

Gene:AQP1; aquaporin 1 (Colton blood group)
Aliases: CO, CHIP28, AQP-CHIP
Location:7p14.3
Summary:This gene encodes a small integral membrane protein with six bilayer spanning domains that functions as a water channel protein. This protein permits passive transport of water along an osmotic gradient. This gene is a possible candidate for disorders involving imbalance in ocular fluid movement. [provided by RefSeq, Aug 2016]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:aquaporin-1
Source:NCBIAccessed: 15 March, 2017

Ontology:

What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 15 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 15 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (8)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: AQP1 (cancer-related)

Crisp RL, Maltaneri RE, Vittori DC, et al.
Red blood cell aquaporin-1 expression is decreased in hereditary spherocytosis.
Ann Hematol. 2016; 95(10):1595-601 [PubMed] Related Publications
Aquaporin-1 (AQP1) is the membrane water channel responsible for changes in erythrocyte volume in response to the tonicity of the medium. As the aberrant distribution of proteins in hereditary spherocytosis (HS) generates deficiencies of proteins other than those codified by the mutated gene, we postulated that AQP1 expression might be impaired in spherocytes. AQP1 expression was evaluated through flow cytometry in 5 normal controls, 1 autoimmune hemolytic anemia, 10 HS (2 mild, 3 moderate, 2 severe, and 3 splenectomized), and 3 silent carriers. The effect of AQP1 inhibitors was evaluated through water flow-based tests: osmotic fragility and hypertonic cryohemolysis. Serum osmolality was measured in 20 normal controls and 13 HS. The effect of erythropoietin (Epo) on AQP1 expression was determined in cultures of erythroleukemia UT-7 cells, dependent on Epo to survive. Independent of erythrocyte size, HS patients showed a lower content of AQP1 in erythrocyte membranes which correlated with the severity of the disease. Accordingly, red blood cells from HS subjects were less sensitive to cryohemolysis than normal erythrocytes after inhibition of the AQP1 water channel. A lower serum osmolality in HS with respect to normal controls suggests alterations during reticulocyte remodeling. The decreased AQP1 expression could contribute to explain variable degrees of anemia in hereditary spherocytosis. The finding of AQP1 expression induced by Epo in a model of erythroid cells may be interpreted as a mechanism to restore the balance of red cell water fluxes.

Liao ZQ, Ye M, Yu PG, et al.
Glioma-Associated Oncogene Homolog1 (Gli1)-Aquaporin1 pathway promotes glioma cell metastasis.
BMB Rep. 2016; 49(7):394-9 [PubMed] Free Access to Full Article Related Publications
Glioma-Associated Oncogene Homolog1 (Gli1) is known to be activated in malignant glioma; however, its downstream pathway has not been fully explained. The aim of this study was to explore the role of Gli1-Aquaporin1 (AQP1) signal pathway in glioma cell survival. Our data suggests that both Gli1 and AQP1 are upregulated in glioma tissues, as in comparison to in normal tissues. These up-regulation phenomena were also observed in glioma U251 and U87 cells. It was demonstrated that Gli1 positively regulated the AQP1 expression. By luciferase reporter gene and ChIP assay, we observed that this modulation process was realized by combination of Gli1 with AQP1 promotor. In addition, knock down of Gli1 by siRNA interference reduced the viability of glioma cells as well as suppressed cell metastasis. Also, the inhibitory effects of cell survival by silenced Gli1 were abrogated by AQP1 overexpression. In summary, glioma cell survival is a regulatory process and can be mediated by Gli1-AQP1 pathway. [BMB Reports 2016; 49(7): 394-399].

Dorward HS, Du A, Bruhn MA, et al.
Pharmacological blockade of aquaporin-1 water channel by AqB013 restricts migration and invasiveness of colon cancer cells and prevents endothelial tube formation in vitro.
J Exp Clin Cancer Res. 2016; 35:36 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Aquaporins (AQP) are water channel proteins that enable fluid fluxes across cell membranes, important for homeostasis of the tissue environment and for cell migration. AQP1 knockout mouse models of human cancers showed marked inhibition of tumor-induced angiogenesis, and in pre-clinical studies of colon adenocarcinomas, forced over-expression of AQP1 was shown to increase angiogenesis, invasion and metastasis. We have synthesized small molecule antagonists of AQP1. Our hypothesis is that inhibition of AQP1 will reduce migration and invasiveness of colon cancer cells, and the migration and tube-forming capacity of endothelial cells in vitro.
METHODS: Expression of AQP1 in cell lines was assessed by quantitative (q) PCR, western blot and immunofluorescence, while expression of AQP1 in human colon tumour tissue was assessed by immunohistochemistry. The effect of varying concentrations of the AQP1 inhibitor AqB013 was tested on human colon cancer cell lines expressing high versus low levels of AQP1, using wound closure (migration) assays, matrigel invasion assays, and proliferation assays. The effect of AqB013 on angiogenesis was tested using an endothelial cell tube-formation assay.
RESULTS: HT29 colon cancer cells with high AQP1 levels showed significant inhibition of migration compared to vehicle control of 27.9% ± 2.6% (p < 0.0001) and 41.2% ± 2.7 (p <0.0001) treated with 160 or 320 μM AqB013 respectively, whereas there was no effect on migration of HCT-116 cells with low AQP1 expression. In an invasion assay, HT29 cells treated with 160 μM of AqB013, showed a 60.3% ± 8.5% decrease in invasion at 144 hours (p < 0.0001) and significantly decreased rate of invasion compared with the vehicle control (F-test, p = 0.001). Almost complete inhibition of endothelial tube formation (angiogenesis assay) was achieved at 80 μM AqB013 compared to vehicle control (p < 0.0001).
CONCLUSION: These data provide good evidence for further testing of the inhibitor as a therapeutic agent in colon cancer.

Willis S, Villalobos VM, Gevaert O, et al.
Single Gene Prognostic Biomarkers in Ovarian Cancer: A Meta-Analysis.
PLoS One. 2016; 11(2):e0149183 [PubMed] Free Access to Full Article Related Publications
PURPOSE: To discover novel prognostic biomarkers in ovarian serous carcinomas.
METHODS: A meta-analysis of all single genes probes in the TCGA and HAS ovarian cohorts was performed to identify possible biomarkers using Cox regression as a continuous variable for overall survival. Genes were ranked by p-value using Stouffer's method and selected for statistical significance with a false discovery rate (FDR) <.05 using the Benjamini-Hochberg method.
RESULTS: Twelve genes with high mRNA expression were prognostic of poor outcome with an FDR <.05 (AXL, APC, RAB11FIP5, C19orf2, CYBRD1, PINK1, LRRN3, AQP1, DES, XRCC4, BCHE, and ASAP3). Twenty genes with low mRNA expression were prognostic of poor outcome with an FDR <.05 (LRIG1, SLC33A1, NUCB2, POLD3, ESR2, GOLPH3, XBP1, PAXIP1, CYB561, POLA2, CDH1, GMNN, SLC37A4, FAM174B, AGR2, SDR39U1, MAGT1, GJB1, SDF2L1, and C9orf82).
CONCLUSION: A meta-analysis of all single genes identified thirty-two candidate biomarkers for their possible role in ovarian serous carcinoma. These genes can provide insight into the drivers or regulators of ovarian cancer and should be evaluated in future studies. Genes with high expression indicating poor outcome are possible therapeutic targets with known antagonists or inhibitors. Additionally, the genes could be combined into a prognostic multi-gene signature and tested in future ovarian cohorts.

Liu YH, Zhu WL
Effects of cetuximab combined with afatinib on the expression of KDR and AQP1 in lung cancer.
Genet Mol Res. 2015; 14(4):16652-61 [PubMed] Related Publications
In this study, we examined the effect of cetuximab (epidermal growth factor receptor monoclonal antibody) combined with afatinib (epidermal growth factor receptorand human epidermal growth factor receptor 2 tyrosine kinase irreversible inhibitor) on the apoptosis of A549 cells and on kinase domain receptor (KDR) and aquaporin 1 (AQP1) expression in A549 cells. A549 cells were cultured in RPMI-1640 and then divided into 4 groups: control group, 1-nM cetuximab group, 25-μM afatinib group, and 1-nM cetuximab + 25-μM afatinib group. After incubation for 48 h, the cell inhibition rate, cell cycle distribution, and invasive ability of A549 cells before and after treatment were examined using MTT, flow cytometry, and transwell assays, respectively. Gene and protein expression levels of KDR and AQP1 were detected by reverse transcription-polymerase chain reaction and western blot analysis. Cetuximab and afatinib significantly inhibited A549 cell growth. Their combination produced greater growth inhibition (P < 0.01). Cetuximab and afatinib both induced the apoptosis of A549 cells, and their combination produced a higher apoptosis rate (P < 0.01). Compared with monotherapy, cetuximab in combination with afatinib induced G1 phase arrest and downregulated the gene and protein expression of KDR and AQP1 (P < 0.05). Cetuximab in combination with afatinib synergistically inhibited the growth and migration of cells and downregulated the gene and protein expression of KDR and AQP1, indicating that a combination of cetuximab and afatinib is a potential strategy for lung cancer therapy.

Zhi F, Wang Q, Xue L, et al.
The Use of Three Long Non-Coding RNAs as Potential Prognostic Indicators of Astrocytoma.
PLoS One. 2015; 10(8):e0135242 [PubMed] Free Access to Full Article Related Publications
Long noncoding RNAs (lncRNAs) are pervasively transcribed and play a key role in tumorigenesis. The aim of the study was to determine the lncRNA expression profile in astrocytomas and to assess its potential clinical value. We performed a three-step analysis to establish the lncRNA profile for astrocytoma: a) the lncRNA expression was examined on 3 astrocytomas as well as 3 NATs (normal adjacent tissues) using the lncRNA microarray; b) the top-hits were validated in 40 astrocytomas (WHO grade II-IV) by quantitative real time-PCR (qRT-PCR); c) the hits with significant differences were re-evaluated using qRT-PCR in 90 astrocytomas. Finally, 7 lncRNAs were found to have a significantly different expression profile in astrocytoma samples compared to the NAT samples. Unsupervised clustering analysis further revealed the potential of the 7-lncRNA profile to differentiate between tumors and NAT samples. The upregulation of ENST00000545440 and NR_002809 was associated with advanced clinical stages of astrocytoma. Using Kaplan-Meier survival analysis, we showed that the low expression of BC002811 or XLOC_010967, or the high expression of NR_002809 was significantly associated with poor patient survival. Moreover, Cox proportional hazard regression analysis revealed that this prognostic impact was independent of other clinicopathological factors. Our results indicate that the lncRNA profile may be a potential prognostic biomarker for the prediction of post-surgical outcomes.

Wu Z, Li S, Liu J, et al.
RNAi-mediated silencing of AQP1 expression inhibited the proliferation, invasion and tumorigenesis of osteosarcoma cells.
Cancer Biol Ther. 2015; 16(9):1332-40 [PubMed] Free Access to Full Article Related Publications
Aquaporin 1 (AQP1), a member of water channel proteins, functions as a water-selective transporting protein in cell membranes. In recent years, AQP1 has been found to be overexpressed in various tumors. However, the molecular mechanism underlying the biological function of AQP1 in osteosarcoma is still unclear. This study was aimed at elucidating the roles of AQP1 in regulating the biological behavior of osteosarcoma cells. In this study, we found that AQP1 mRNA was elevated in osteosarcoma tissue. High level of AQP1 was associated with poor prognosis in osteosarcoma. Then, we found that knockdown of AQP1 in osteosarcoma cells, U2OS or MG63 cells inhibited cell proliferation and significantly increased cells population in G1 phase. Additionally, suppressing AQP1 expression in osteosarcoma cells dramatically induced cell apoptosis. We also found that down-regulation of AQP1 significantly inhibited cell adhesion and invasion. More importantly, AQP1 knockdown inhibited tumor growth in vivo and prolonged the survival time of nude mice. Gene set enrichment analysis (GSEA) showed that transforming growth factor-β (TGF-β) signaling pathway and focal adhesion genes was correlatively with AQP1 expression. In addition, real time PCR and western blot analysis revealed that expression of TGF-β1/TGF-β2, RhoA and laminin β 2 (LAMB2) was remarkably impaired by AQP1 silencing. In conclusion, AQP1 may be a useful diagnosis and prognosis marker for osteosarcoma. AQP1 knockdown can effectively inhibit cell proliferation, adhesion, invasion and tumorigenesis by targeting TGF-β signaling pathway and focal adhesion genes, which may serve a promising therapeutic strategy for osteosarcoma.

Wei X, Dong J
Aquaporin 1 promotes the proliferation and migration of lung cancer cell in vitro.
Oncol Rep. 2015; 34(3):1440-8 [PubMed] Related Publications
To examine the potential role of aquaporin 1 (AQP1) in lung cancer progression, the effects of AQP1 expression and underlying mechanisms on cell proliferation and migration were investigated on LLC and LTEP-A2 cell lines in vitro. LLC and LTEP-A2 lung cancer cells with a discrepant AQP1 expression level were used to determine the role of AQP1 in cancer cell proliferation and migration potential. An immuno-fluorescence assay was used to detect AQP1 expression levels in the LLC and LTEP-A2 cell lines. The method targeting the knockdown of AQP1 on lung cancer cell lines by siRNA was established and validated by RT-PCR and western blot analysis. The proliferation and migration abilities of AQP1 knockdown cell lines were detected by MTT, invasion and wound-healing assays. Moreover, the alteration of MMP-2, MMP-9, TGF-β and epidermal growth factor receptor (EGFR) expression, associated with the migration and metastasis potential of lung cancer cell lines, was identified by western blot analysis in transfected cells. In the tumor cell migration and invasion test, AQP1 knockdown significantly decreased the migration and invasion of AQP1-siRNA cells. Additionally, the expression levels of MMPs were markedly decreased after AQP1-siRNA treatment in the two cell lines. Moreover, the decrease of MMP-2/-9 expression on lung cancer cell lines was associated with AQP1-siRNA doses. However, AQP1 knockdown did not have a significant effect on TGF-β and EGFR. The results suggest that AQP1 may facilitate lung cancer cell proliferation and migration in an MMP-2 and-9-dependent manner.

Noell S, Fallier-Becker P, Mack AF, et al.
Water Channels Aquaporin 4 and -1 Expression in Subependymoma Depends on the Localization of the Tumors.
PLoS One. 2015; 10(6):e0131367 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: We analyzed aquaporin 4 and -1 expression in subependymomas, benign and slow growing brain tumors WHO grade I. Ten subependymoma cases were investigated, five of the fossa inferior and five of the fossa superior.
METHODS AND RESULTS: Using immunohistochemistry, we observed different aquaporin expression patterns depending on localization: aquaporin 4 and -1 were detected in infratentorial subependymomas in the entire tumor tissue. In contrast, supratentorial subependymomas revealed aquaporin 4 and -1 expression only in border areas of the tumor. PCR analyses however showed no difference in aquaporin 4 expression between all subependymomas independent of localization but at higher levels than in normal brain. In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples. The reason for the different distribution pattern of aquaporin 4 in subependymomas still remains unclear. On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found. This was similar to our previous findings in malignant glioblastomas. From these studies, we know that extracellular matrix molecules within the tumor like agrin and its receptor alpha-dystroglycan are involved in forming orthogonal arrays of particles. In subependymomas neither agrin nor alpha-dystroglycan were detected around blood vessels.
CONCLUSIONS: Taken together, we show in this study that in the benign subependymomas aquaporins 1 and 4 are dramatically redistributed and upregulated. We speculate that extracellular environments of infra- and supratentorial subependymomas are different and lead to different distribution patterns of aquaporin 4 and -1.

Lehnerdt GF, Bachmann HS, Adamzik M, et al.
AQP1, AQP5, Bcl-2 and p16 in pharyngeal squamous cell carcinoma.
J Laryngol Otol. 2015; 129(6):580-6 [PubMed] Related Publications
OBJECTIVE: This study aimed to link expression patterns of AQP1, AQP5, Bcl-2 and p16 to clinicopathological characteristics of oro-hypopharyngeal squamous cell carcinomas.
METHODS: Immunohistochemical expression of AQP1, AQP5, Bcl-2 and p16 was investigated in 107 consecutive oro-hypopharyngeal squamous cell carcinoma cases. Molecular interrelationship and correlations with clinicopathological parameters and survival were computed.
RESULTS: AQP1 was expressed exclusively by a subgroup of basaloid-like squamous cell carcinomas. AQP5 was detected in 25.2 per cent of the samples, showing significant association with the absence of p16 and Bcl-2 (p = 0.018; p = 0.010). In multivariate analysis, overexpression of p16 was significantly correlated with favourable overall survival (p = 0.014).
CONCLUSION: AQP5 defined a subset of patients with Bcl-2-negative and p16-negative tumours with a poor clinical outcome. AQP1 was found to be a marker of a subgroup of aggressive basaloid-like squamous cell carcinomas. These findings suggest that AQP1 and AQP5 are interesting candidates for further studies on risk group classification and personalised treatment of oro-hypopharyngeal squamous cell carcinomas.

Lee S, Choi JS, Kim HJ, et al.
Impact of Irradiation on laryngeal hydration and lubrication in rat larynx.
Laryngoscope. 2015; 125(8):1900-7 [PubMed] Related Publications
OBJECTIVES: The larynx is susceptible to irradiation, which causes significant vocal fold (VF) edema and dehydration shortly after radiotherapy for head and neck cancers. However little is known about radiation-induced damage to VF liquid homeostasis. To evaluate the effects of irradiation on VF hydration and lubrication, we investigated changes in water transporters (aquaporins [AQPs]) and mucin production in vivo and ex vivo, as well as morphometric changes in the laryngeal mucosa and glands of irradiated rat larynges.
STUDY DESIGN: Animal study.
MATERIALS AND METHODS: Local irradiation at 18 Gy was delivered to rat larynges. Histologic changes in laryngeal mucosa and glands were observed by light microscopy, and the distributions of AQPs and mucin were investigated by immunofluorescence staining 3 months after irradiation. Early effects on gene regulation of AQPs and mucin were evaluated by quantitative real-time polymerase chain reaction of the extirpated VFs and subglottic laryngeal mucosa at 12, 24, and 72 hours after irradiation.
RESULTS: Laryngeal glands exhibited severe atrophic changes and showed decreased density throughout the irradiated larynx. The expression of AQP1, 4, 5, and mucin in VFs, as well as AQP5 and mucin in submucosal laryngeal glands, decreased significantly 3 months after irradiation. An ex vivo study revealed that the gene expression of AQP5 in VF tissues was significantly downregulated at 12 hours postirradiation.
CONCLUSION: Laryngeal irradiation induces damage in laryngeal mucosal barriers and alters laryngeal liquid homeostasis, which may be one reason for vocal dysfunction following irradiation.
LEVEL OF EVIDENCE: N/A.

Kang BW, Kim JG, Lee SJ, et al.
Expression of aquaporin-1, aquaporin-3, and aquaporin-5 correlates with nodal metastasis in colon cancer.
Oncology. 2015; 88(6):369-76 [PubMed] Related Publications
OBJECTIVES: The clinical significance of aquaporin-1 (AQP1), aquaporin-3 (AQP3), and aquaporin-5 (AQP5) expression was analyzed in a large number of patients with colon cancer.
METHODS: AQP1, AQP3, and AQP5 expression was investigated based on the immunohistochemistry of tissue microarray specimens from 486 colon cancer patients who underwent curative surgery. Scores were given to the staining intensity and percentage of positive cells, and the staining score was defined as the sum of these scores then used to categorize the AQP expression as negative, weakly AQP-positive, or strongly AQP-positive.
RESULTS: A total of 298 (61.3%) patients were identified as strongly AQP1-positive (staining score ≥ 6), while 38 (7.8%) were strongly AQP3-positive and 145 (29.8%) were strongly AQP5-positive. The overexpression of AQP1, AQP3, and AQP5 was significantly correlated with lymph node metastasis in a multivariate logistic analysis (AQP1, p = 0.026; AQP3, p = 0.023; AQP5, p = 0.003). While the multivariate survival analysis, which included age, histology, TNM stage, and CEA level showed that the expression of AQP1, AQP3, and AQP5 had no effect on the overall survival and disease-free survival.
CONCLUSIONS: The current study found a significant correlation between AQP1, AQP3, and AQP5 expression and lymph node metastasis in patients with surgically resected colon cancer.

Chen R, Shi Y, Amiduo R, et al.
Expression and prognostic value of aquaporin 1, 3 in cervical carcinoma in women of Uygur ethnicity from Xinjiang, China.
PLoS One. 2014; 9(2):e98576 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Overexpression of several aquaporins has been reported in different types of human cancer but the role of aquaporins in carcinogenesis has not yet been clearly defined. There is few report concerning role of aquaporins in human cervical carcinogenesis so far. Here, we determined the expression and prognostic value of aquaporin 1, 3 in cervical carcinoma in Chinese women of Uygur ethnicity.
METHODS AND RESULTS: Real-time PCR analyses demonstrated aquaporin 1, 3 mRNA were differentially expressed in cervical carcinoma, CIN 2-3 and mild cervicitis. Immunofluorescent and immunohistochemical analyses demonstrated aquaporin 1 was predominantly localized to stromal endothelial cells in cervical lesions. Aquaporin 3 was localized to the membrane of normal squamous epithelium, CIN and carcinoma cells. Aquaporin 1 and 3 were upregulated in cervical cancer compared to mild cervicitis and CIN2-3 (P<0.05); Tumor expression of aquaporin 1, 3 significantly increased in advanced stage disease, and patients with deeper tumor infiltration, lymph node metastases or larger tumor volume (P<0.05). Multivariate analysis demonstrated that aquaporin 1, 3 were not independent prognostic factors in cervical carcinoma.
CONCLUSION: Aquaporins may participate in the initiation and progression of cervical carcinoma by promoting tumor growth, invasion or lymph node metastasis. Further study is required to determine whether aquaporins have potential as prognostic factors in cervical cancer.

Xia H, Ye J, Bai H, Wang C
[Effects of cetuximab combined with celecoxib on apoptosis and KDR and AQP1 expression in lung cancer].
Zhongguo Fei Ai Za Zhi. 2013; 16(12):625-31 [PubMed] Related Publications
BACKGROUND AND OBJECTIVE: Neoadjuvant chemotherapy is a new development in the treatment of lung cancer. In recent years, cetuximab and celecoxib have been commonly used in this procedure. This study aims to explore the effect of cetuximab combined with celecoxib on apoptosis and KDR and AQP1 expression in lung cancer A549 cells.
METHODS: The cells were cultured in RPMI-1640 and then divided into four groups: control group, 1 nmol/L cetuximab group, 25 µmol/L celecoxib group, and 1 nmol/L cetuximab+25 µmol/L celecoxib group. The treatment time was 48 h. The mRNA and protein expression levels of KDR and AQP1 were detected by RT-PCR and Western blot, respectively. The apoptosis, proliferation, and invasive ability of A549 cells before and after transfection were examined using flow cytometry, MTT, and transwell methods.
RESULTS: Cetuximab and celecoxib inhibited the growth of A549 cells in a dose-dependent manner. Their combination produced a greater growth inhibition than when either was used alone (P<0.01). Cetuximab and celecoxib both induced the apoptosis of A549 cells, and their combination produced a higher apoptosis rate (P<0.01). Cetuximab in combination with celecoxib also induced G1 phase arrest and downregulated the expression of KDR and AQP1 in A549 cells (P<0.05). As a result, the invasion ability of the A549 cells was significantly decreased.
CONCLUSIONS: Cetuximab in combination with celecoxib can synergistically inhibit the growth of A549 cells and downregulate the expression of KDR and AQP1 in A549 cells. The combination of cetuximab and celecoxib is a potential strategy for lung cancer therapy.

Esteva-Font C, Jin BJ, Verkman AS
Aquaporin-1 gene deletion reduces breast tumor growth and lung metastasis in tumor-producing MMTV-PyVT mice.
FASEB J. 2014; 28(3):1446-53 [PubMed] Free Access to Full Article Related Publications
Aquaporin 1 (AQP1) is a plasma membrane water-transporting protein expressed strongly in tumor microvascular endothelia. We previously reported impaired angiogenesis in implanted tumors in AQP1-deficient mice and reduced migration of AQP1-deficient endothelial cells in vitro. Here, we investigated the consequences of AQP1 deficiency in mice that spontaneously develop well-differentiated, luminal-type breast adenomas with lung metastases [mouse mammary tumor virus-driven polyoma virus middle T oncogene (MMTV-PyVT)]. AQP1(+/+) MMTV-PyVT mice developed large breast tumors with total tumor mass 3.5 ± 0.5 g and volume 265 ± 36 mm(3) (SE, 11 mice) at age 98 d. Tumor mass (1.6±0.2 g) and volume (131±15 mm(3), 12 mice) were greatly reduced in AQP1(-/-) MMTV-PyVT mice (P<0.005). CD31 immunofluorescence showed abnormal microvascular anatomy in tumors of AQP1(-/-) MMTV-PyVT mice, with reduced vessel density. HIF-1α expression was increased in tumors in AQP1(-/-) MMTV-PyVT mice. The number of lung metastases (5±1/mouse) was much lower than in AQP1(+/+) MMTV-PyVT mice (31±8/mouse, P<0.005). These results implicate AQP1 as an important determinant of tumor angiogenesis and, hence, as a potential drug target for adjuvant therapy of solid tumors.

El Hindy N, Rump K, Lambertz N, et al.
The functional Aquaporin 1 -783G/C-polymorphism is associated with survival in patients with glioblastoma multiforme.
J Surg Oncol. 2013; 108(7):492-8 [PubMed] Related Publications
BACKGROUND: Despite a dismal prognosis, variability exists regarding the survival-time in patients with glioblastoma-multiforme (GBM), which may be explained by genetic variation. A possible candidate-gene for such variation is Aquaporin-1 (AQP1), since Aquaporin-1-expression influences the pathogenesis and outcome of various malignancies. Functional genetic variants in the promoter of AQP1, modifying Aquaporin-1-expression, could be associated with altered survival in patients with GBM.
METHODS: We sequenced the human AQP1-promoter to detect novel sequence variants, which might impact on Aquaporin-1-expression and tested the hypothesis, that functional single nucleotide polymorphisms are associated with different survival-times of patients suffering from GBM.
RESULTS: Sequencing the AQP1-promoter revealed a novel -783G/C-polymorphism. Reporter-assays showed that substitution of G for C was associated both with increased transcriptional-activation of the AQP1-promoter by serum and with increased AQP1 mRNA expression. Finally, we assessed in a cohort of 155 Caucasian patients with GBM whether the functional single-nucleotide-783G/C-polymorphism is associated with survival-time. Cox-regression analyses revealed the AQP1 -783G/C genotype status as an independent prognostic-factor when jointly considering other predictors of survival. Homozygous CC subjects had a significantly worse outcome compared to GC/GG genotypes (hazard ratio: 3.09; 95% CI, 1.43-6.65; P = 0.004).
CONCLUSIONS: Our findings suggest the novel AQP1 polymorphism as a survival prognosticator in patients suffering from GBM that could help to identify a subgroup of patients at high risk for death. Further studies are necessary to reveal the exact molecular mechanisms.

Jiang YS, Wang FR
Caloric restriction reduces edema and prolongs survival in a mouse glioma model.
J Neurooncol. 2013; 114(1):25-32 [PubMed] Related Publications
Regardless of their cell type of origin, all aggressive brain tumors, such as malignant gliomas and metastatic tumors produce brain edema, which is an important cause of patient morbidity and mortality. Caloric restriction (CR) has long been recognized as a natural therapy that improves health, promotes longevity, and significantly reduces both the incidence and growth of many tumor types. The aim of present work was to investigate the effect of CR on edema and survival in the mice implanted with U87 gliomas. We found that CR significantly inhibited the intracerebral tumor growth, attenuated brain edema, and ultimately prolonged survival of mice with U87 gliomas. Plasma corticosterone level was found higher and serum VEGF and IGF-1 levels were found lower in CR, when compared to AL group. CR upregulated tight junction proteins including claudin-1, claudin-5 and ZO-1, downregulated VEGF and VEGFR2, enhanced α-SMA expression, and reduced AQP1 expression in U87 gliomas. In addition, CR suppressed inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) formation in U87 gliomas. In conclusion, CR attenuated edema in U87 orthotopic mouse glioma model associated with elevation of corticosterone, suppression of VEGF/VEGFR2, improvement of tight junctions, and suppression of iNOS expression and NO formation. Our results suggested that CR might be an effective therapy for recurrent malignant brain cancers through alleviating associated edema.

Cao XC, Zhang WR, Cao WF, et al.
Aquaporin3 is required for FGF-2-induced migration of human breast cancers.
PLoS One. 2013; 8(2):e56735 [PubMed] Free Access to Full Article Related Publications
PURPOSE: The aquaporin (AQP) family consists of a number of small integral membrane proteins that transport water and glycerol. AQPs are critical for trans-epithelial fluid transport. Recent reports demonstrated that AQPs, particularly AQP1 and AQP5, are expressed in high grade tumor cells of a variety of tissue origins, and that AQPs are involved in cell migration and metastasis. Based on this background, we examined whether AQP3, another important member of the AQP family, could facilitate cell migration in human breast cancers.
METHODS: Potential role of AQP3 was examined using two representative breast cancer cell lines (MDA-MB-231 and Bcap-37). Briefly, AQP3 expression was inhibited with a lentivirus construct that stably expressed shRNA against the AQP3 mRNA. AQP3 expression inhibition was verified with Western blot. Cell migration was examined using a wound scratch assay in the presence of fibroblast growth factor-2 (FGF-2). In additional experiments, AQP3 was inhibited by CuSO4. Fibroblast growth factor receptor (FGFR) kinase inhibitor PD173074, PI3K inhibitor LY294002, and MEK1/2 inhibitor PD98059 were used to dissect the molecular mechanism of FGF-2 induced AQP3 expression.
RESULTS: FGF-2 treatment increased AQP3 expression and induced cell migration in a dose dependent manner. Silencing AQP3 expression by a lentiviral shRNA inhibited FGF-2 induced cell migration. CuSO4, a water transport inhibitor selective for AQP3, also suppressed FGF-2-induced cell migration. The FGFR kinase inhibitor PD173074, significantly inhibited FGF-2-induced AQP3 expression and cell migration. The PI3K inhibitor LY294002 and MEK1/2 inhibitor PD98059 inhibited, but not fully blocked, FGF-2-induced AQP3 expression and cell migration.
CONCLUSIONS: AQP3 is required for FGF-2-induced cell migration in cultured human breast cancer cells. Our findings also suggest the importance of FGFR-PI3K and FGFR-ERK signaling in FGF-2-induced AQP3 expression. In summary, our findings suggest a novel function of AQP3 in cell migration and metastasis of breast cancers.

Zou LB, Shi S, Zhang RJ, et al.
Aquaporin-1 plays a crucial role in estrogen-induced tubulogenesis of vascular endothelial cells.
J Clin Endocrinol Metab. 2013; 98(4):E672-82 [PubMed] Related Publications
CONTEXT: Aquaporin-1 (AQP1) has been proposed as a mediator of estrogen-induced angiogenesis in human breast cancer and endometrial cancer. Elucidation of the molecular mechanisms governing AQP1-mediated, estrogen-induced angiogenesis may contribute to an improved understanding of tumor development.
OBJECTIVE: Our objective was to identify the estrogen-response element (ERE) in the promoter of the Aqp1 gene and investigate the effects and mechanisms of AQP1 on estrogen-induced tubulogenesis of vascular endothelial cells.
SETTING: The study was conducted in a university hospital in eastern China.
MAIN OUTCOME MEASURES: Immunohistological, real-time PCR and Western blot analyses were used to determine the expression AQP1 mRNA and protein in vascular endothelial cells. Chromatin immunoprecipitation analyses and luciferase reporter assays identified ERE-like motif in the promoter of the Aqp1 gene.
RESULTS: Expression of AQP1 in blood vessels of human breast and endometrial carcinoma tissues were significantly higher than controls. Estradiol (E2) dose-dependently increased the expression levels of AQP1 mRNA and protein in human umbilical vein endothelial cells (HUVECs). A functional ERE-like motif was identified in the promoter of the Aqp1 gene. AQP1 colocalized with ezrin, a component of the ezrin/radixin/moesin protein complex, and, ezrin colocalized with filamentous actin in HUVECs. Knockdown of AQP1 or ezrin with specific small interfering RNA significantly attenuated the formation of transcytoplasmic filamentous actin stress fibers induced by E2 and inhibited E2-enhanced cell proliferation, migration, invasion, and tubule formation of HUVECs.
CONCLUSIONS: Estrogen induces AQP1 expression by activating ERE in the promoter of the Aqp1 gene, resulting in tubulogenesis of vascular endothelial cells. These results provide new insights into the molecular mechanisms underpinning the angiogenic effects of estrogen.

Deb P, Pal S, Dutta V, et al.
Correlation of expression pattern of aquaporin-1 in primary central nervous system tumors with tumor type, grade, proliferation, microvessel density, contrast-enhancement and perilesional edema.
J Cancer Res Ther. 2012 Oct-Dec; 8(4):571-7 [PubMed] Related Publications
OBJECTIVES: Brain edema, a hallmark of malignant brain tumors, continues to be a major cause of mortality. The underlying molecular mechanisms are poorly understood and thought to be mediated through membrane water-channels: aquaporins (AQP1,4,9). The abnormal upregulation of AQP1 in certain glial neoplasms has suggested a potential role in tumor pathogenesis, apart from being a novel target for newer therapeutic regimen. This study was undertaken to evaluate the expression of AQP1 in primary CNS tumors of various histologic types and grades, and its correlation with contrast-enhancement, perilesional edema, histomorphology, proliferation index and microvessel density.
MATERIALS AND METHODS: Biopsy tissues from 30 patients (10 each from gliomas, meningiomas and other primary CNS tumors) were studied. Autopsy brain sections served as control. AQP1-immunoreactivity was correlated with histomorphology, radiology, proliferation index and microvessel density (MVD).
RESULTS: AQP1 expression was increased in gliomas and ependymal tumors as compared to meningiomas. Intratumoral expression was homogenous in high-grade and membranous in low-grade neoplasms, while peritumoral areas showed expression around vessels and reactive astrocytes. High-grade tumors showed peritumoral upregulation, while low-grade had intense intratumoral expression. A trend of positive correlation was observed between AQP1-immunopositivity and increasing grade, higher MIB-1LI, increasing contrast-enhancement and more perilesional edema, and elevated MVD with raised AQP1:MVD ratio.
CONCLUSIONS: AQP1-immunoexpression had a good correlation with high-grade tumors. AQP-upregulation in perilesional areas of high-grade tumors suggests its role in vasogenic edema. Further studies involving other AQP molecules, vascular endothelial growth factor (VEGF) and hypoxia inducible factor-1 α (HIF-1α) should be undertaken to evaluate its possible role as a potential surrogate marker of high-grade tumors heralding poor outcome, inhibition of which may serve as the basis for future targeted therapy.

Jagirdar R, Solenov EI, Hatzoglou C, et al.
Gene expression profile of aquaporin 1 and associated interactors in malignant pleural mesothelioma.
Gene. 2013; 517(1):99-105 [PubMed] Related Publications
Overexpression of AQP1 has recently been shown to be an independent prognostic factor in pleural mesothelioma favoring survival. This paper presents a data mining and bioinformatics approach towards the evaluation of the gene expression profile of AQP1 in malignant pleural mesothelioma and of AQP1 associated markers in the context of mesothelioma disease phenotype, CDKN2A gene deletion, sex and asbestos exposure. The data generated were thus again subjected to differential expression profile analysis. Here we report that AQP1 is overexpressed in epithelioid mesothelioma and identify TRIP6 and EFEMP2 as candidate genes for further investigation in mesothelioma.

Wei M, Shi R, Jiang L, et al.
[Role of aquaporin-1 gene in erythroid differentiation of erythroleukemia K562 cells induced by retinoic acid].
Nan Fang Yi Ke Da Xue Xue Bao. 2012; 32(12):1689-94 [PubMed] Related Publications
OBJECTIVE: To explore the role of aquaporin-1 (AQP1) gene in erythroid differentiation of erythroleukemia K562 cells induced by retinoic acid (RA).
METHODS: K562 cells were cultured in the presence of 1 µmol/L RA for varying lengths of time, and γ-globin mRNA expression and hemoglobin content in the cells were detected by real-time PCR (RT-PCR) and ultraviolet spectrophotometry, respectively, to evaluate the erythroid differentiation of K562 cells. RT-PCR and Western blotting were used to examine AQP1 expression in the cells following RA treatment. A retroviral expression vector of AQP1 small interfering RNA (pSUPER-retro-puro-shAQP1) was constructed and transfected into K562 cells to establish a K562 cell line with stable AQP1 down-regulation (K562-shAQP1), in which the changes in γ-globin and hemoglobin expressions after RA treatment were detected.
RESULTS: RA treatment significantly increased γ-globin and hemoglobin expressions in K562 cells (P<0.01), causing also significantly enhanced AQP1 mRNA and protein expressions over time (P<0.01). Transfection with the recombinant plasmids pSuper-retro-puro-shAQP1 resulted in stable AQP1 suppression in K562 cells (P<0.01), which showed markedly reduced γ-globin and hemoglobin expressions after RA induction as compared to the control K562 cells (P<0.01).
CONCLUSION: K562 cells show a significant increase of AQP1 expression after RA-induced erythroid differentiation, and suppression of AQP1 expression can partially block the effect of RA, suggesting the important role of AQP1 in RA-induced erythroid differentiation of K562 cells.

Nicchia GP, Stigliano C, Sparaneo A, et al.
Inhibition of aquaporin-1 dependent angiogenesis impairs tumour growth in a mouse model of melanoma.
J Mol Med (Berl). 2013; 91(5):613-23 [PubMed] Related Publications
Prohibiting angiogenesis is an important therapeutic approach for fighting cancer and other angiogenic related diseases. Research focused on proteins that regulate abnormal angiogenesis has attracted intense interest in both academia and industry. Such proteins are able to target several angiogenic factors concurrently, thereby increasing the possibility of therapeutic success. Aquaporin-1 (AQP1) is a water channel membrane protein that promotes tumour angiogenesis by allowing faster endothelial cell migration. In this study we test the hypothesis that AQP1 inhibition impairs tumour growth in a mouse model of melanoma. After validating the inhibitor efficacy of two different AQP1 specific siRNAs in cell cultures, RNA interference experiments were performed by intratumoural injections of AQP1 siRNAs in mice. After 6 days of treatment, AQP1 siRNA treated tumours showed a 75 % reduction in volume when compared to controls. AQP1 protein level, in AQP1 knockdown tumours, was around 75 % that of the controls and was associated with a significant 40 % reduced expression of the endothelial marker, Factor VIII. Immunofluorescence analysis of AQP1 siRNA treated tumours showed a significantly lower microvessel density. Time course experiments demonstrated that repeated injections of AQP1 siRNA over time are effective in sustaining the inhibition of tumour growth. Finally, we have confirmed the role of AQP1 in sustaining an active endothelium during angiogenesis and we have shown that AQP1 reduction causes an increase in VEGF levels. In conclusion, this study validates AQP1 as a pro-angiogenic protein, relevant for the therapy of cancer and other angiogenic-related diseases such as psoriasis, endometriosis, arthritis and atherosclerosis.

Stephen JH, Sievert AJ, Madsen PJ, et al.
Spinal cord ependymomas and myxopapillary ependymomas in the first 2 decades of life: a clinicopathological and immunohistochemical characterization of 19 cases.
J Neurosurg Pediatr. 2012; 9(6):646-53 [PubMed] Related Publications
OBJECT: Primary spinal cord ependymomas (EPNs) are rare in children, comprising classical WHO Grade II and III tumors and Grade I myxopapillary ependymomas (MEPNs). Despite their benign histology, recurrences and neural-axis dissemination have been reported in up to 33% MEPNs in the pediatric population. Treatment options beyond resection are limited, and little is known about their tumorigenesis. The purpose of this study was to explore the tumor biology and outcomes in a consecutive series of pediatric patients treated at a single institution.
METHODS: The authors performed a retrospective clinicopathological review of 19 patients at a tertiary referral children's hospital for resection of a spinal cord ependymoma. The population included 8 patients with a pathological diagnosis of MEPN and 11 patients with a pathological diagnosis of spinal EPN (10 cases were Grade II and 1 case was Grade III). The upregulation of the following genes HOXB13, NEFL, PDGFRα, EGFR, EPHB3, AQP1, and JAGGED 1 was studied by immunohistochemistry from archived paraffin-embedded tumor samples of the entire cohort to compare the expression in MEPN versus EPN.
RESULTS: Gross-total resection was achieved in 75% of patients presenting with MEPNs and in 100% of those with EPNs. The average follow-up period was 79 months for the MEPN subset and 53 months for Grade II/III EPNs. Overall survival for both subsets was 100%. However, event-free survival was only 50% for patients with MEPNs. Of note, in all cases involving MEPNs that recurred, the patients had undergone gross-total resection on initial surgery. In contrast, there were no tumor recurrences in patients with EPNs. Immunohistochemistry revealed no significant differences in protein expression between the two tumor types with the exception of EPHB3, which demonstrates a tendency to be positive in MEPNs (6 reactive tumors of 9) rather than in EPN (2 reactive tumors of 10).
CONCLUSIONS: The authors' experience shows that, following a gross-total resection, MEPNs are more likely to recur than their higher-grade counterpart, EPNs. This supports the recommendation for close long-term radiological follow-up of pediatric patients with MEPNs to monitor for recurrence, despite the tumor's low-grade histological feature. No significant difference in the protein expression of HOXB13, NEFL, PDGFRα, EGFR, EPHB3, AQP1, and JAGGED 1 was present in this selected cohort of pediatric patients.

Pan XY, Guo H, Han J, et al.
Ginsenoside Rg3 attenuates cell migration via inhibition of aquaporin 1 expression in PC-3M prostate cancer cells.
Eur J Pharmacol. 2012; 683(1-3):27-34 [PubMed] Related Publications
Ginsenoside Rg3 (Rg3), one of the bioactive extracts found in ginseng root, was reported to have anti-cancer activity in various cancer models. The anti-proliferation effect of Rg3 on prostate cancer cells has been well reported. To test whether Rg3 has an anti-metastatic effect on prostate cancer, we treated a highly metastatic PC-3M prostate cancer cell line with Rg3. We found that Rg3 (10μM) led to remarkable inhibition of PC-3M cell migration. Simultaneously, exposure to Rg3 suppressed expression of the aquaporin 1 (AQP1) water channel protein, which has previously been reported to be involved in cell migration. Overexpression of AQP1 attenuated Rg3-induced inhibition of cell migration, and introduction of a shRNA targeting AQP1 abrogated the inhibitory effect of Rg3, although the basal level of cell migration was decreased by RNA interference. In mechanism study, estrogen receptor- and glucocorticoid receptor-dependent pathways are proved uninvolved in the AQP1 regulation by Rg3. However, Rg3 treatment triggered the activation of p38 MAPK; and SB202190, a specific inhibitor of p38 MAPK, antagonized the Rg3-induced regulation of AQP1 and cell migration, suggesting a crucial role for p38 in the regulation process. Deletion analysis of the promoter region of AQP1 was also conducted using dual-luciferase assay, which indicated that the -1000 bp to -200 bp promoter region was involved in the AQP1 regulation by Rg3. In all, we conclude that Rg3 effectively suppresses migration of PC-3M cells by down-regulating AQP1 expression through p38 MAPK pathway and some transcription factors acting on the AQP1 promoter.

Fossdal G, Vik-Mo EO, Sandberg C, et al.
Aqp 9 and brain tumour stem cells.
ScientificWorldJournal. 2012; 2012:915176 [PubMed] Free Access to Full Article Related Publications
Several studies have implicated the aquaporins (aqp) 1, 4, and 9 in the pathogenesis of malignant brain tumours, suggesting that they contribute to motility, invasiveness, and oedema formation and facilitate metabolism in tumour cells under hypoxic conditions. We have studied the expression of aqp1, 4, and 9 in biopsies from glioblastomas, isolated tumour stem cells grown in a tumoursphere assay and analyzed the progenitor and differentiated cells from these cultures. We have compared these to the situation in normal rat brain, its stem cells, and differentiated cells derived thereof. In short, qPCR in tumour tissue showed presence of aqp1, 4, and 9. In the tumour progenitor population, aqp9 was markedly more highly expressed, whilst in tumour-derived differentiated cells, aqp4 was downregulated. However, immunostaining did not reveal increased protein expression of aqp9 in the tumourspheres containing progenitor cells; in contrast, its expression (both mRNA and protein) was high in differentiated cultures. We, therefore, propose that aquaporin 9 may have a central role in the tumorigenesis of glioblastoma.

Wang SL, Gao RT
Gene transfer-mediated functional restoration for irradiated salivary glands.
Chin J Dent Res. 2011; 14(1):7-13 [PubMed] Related Publications
Radiation therapy for malignant tumours in the head and neck region are inevitably associated with significant long-term injury to the salivary glands, often resulting in salivary gland hypofunction. The subsequent lack of saliva production leads to many functional and quality-of-life problems for affected patients and there is no effective method to eliminating this problem caused by radiation treatments. Although many studies have been done in animal models, the mechanism of this injury in humans is still unclear. In this review, an animal model (miniature pigs) used in irradiated research is mainly discussed. This review also presents the progress made to date on the gene transfer-mediated functional restoration of irradiated salivary glands and the possibilities provided by future interventions to prevent radiation damage to salivary glands.

Shao C, Sun W, Tan M, et al.
Integrated, genome-wide screening for hypomethylated oncogenes in salivary gland adenoid cystic carcinoma.
Clin Cancer Res. 2011; 17(13):4320-30 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Salivary gland adenoid cystic carcinoma (ACC) is a rare malignancy that is poorly understood. To look for relevant oncogene candidates under the control of promoter methylation, an integrated, genome-wide screen was conducted.
EXPERIMENTAL DESIGN: Global demethylation of normal salivary gland cell strains using 5-aza-2'-deoxycytidine (5-aza-dC) and trichostatin A (TSA), followed by expression array analysis was conducted. ACC-specific expression profiling was generated using expression microarray analysis of primary ACC and normal samples. Next, the two profiles were integrated to identify a subset of genes for further validation of promoter demethylation in ACC versus normal. Finally, promising candidates were further validated for mRNA, protein, and promoter methylation levels in larger ACC cohorts. Functional validation was then conducted in cancer cell lines.
RESULTS: We found 159 genes that were significantly re-expressed after 5-aza-dC/TSA treatment and overexpressed in ACC. After initial validation, eight candidates showed hypomethylation in ACC: AQP1, CECR1, C1QR1, CTAG2, P53AIP1, TDRD12, BEX1, and DYNLT3. Aquaporin 1 (AQP1) showed the most significant hypomethylation and was further validated. AQP1 hypomethylation in ACC was confirmed with two independent cohorts. Of note, there was significant overexpression of AQP1 in both mRNA and protein in the paraffin-embedded ACC cohort. Furthermore, AQP1 was upregulated in 5-aza-dC/TSA-treated SACC83. Finally, AQP1 promoted cell proliferation and colony formation in SACC83.
CONCLUSIONS: Our integrated, genome-wide screening method proved to be an effective strategy for detecting novel oncogenes in ACC. AQP1 is a promising oncogene candidate for ACC and is transcriptionally regulated by promoter hypomethylation.

Warth A, Muley T, Meister M, et al.
Loss of aquaporin-4 expression and putative function in non-small cell lung cancer.
BMC Cancer. 2011; 11:161 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Aquaporins (AQPs) have been recognized to promote tumor progression, invasion, and metastasis and are therefore recognized as promising targets for novel anti-cancer therapies. Potentially relevant AQPs in distinct cancer entities can be determined by a comprehensive expression analysis of the 13 human AQPs.
METHODS: We analyzed the presence of all AQP transcripts in 576 different normal lung and non-small cell lung cancer (NSCLC) samples using microarray data and validated our findings by qRT-PCR and immunohistochemistry.
RESULTS: Variable expression of several AQPs (AQP1, -3, -4, and -5) was found in NSCLC and normal lung tissues. Furthermore, we identified remarkable differences between NSCLC subtypes in regard to AQP1, -3 and -4 expression. Higher transcript and protein levels of AQP4 in well-differentiated lung adenocarcinomas suggested an association with a more favourable prognosis. Beyond water transport, data mining of co-expressed genes indicated an involvement of AQP4 in cell-cell signalling, cellular movement and lipid metabolism, and underlined the association of AQP4 to important physiological functions in benign lung tissue.
CONCLUSIONS: Our findings accentuate the need to identify functional differences and redundancies of active AQPs in normal and tumor cells in order to assess their value as promising drug targets.

Li Q, Zhang B
Expression of aquaporin-1 in nasopharyngeal cancer tissues.
J Otolaryngol Head Neck Surg. 2010; 39(5):511-5 [PubMed] Related Publications
OBJECTIVE: To investigate the expression of aquaporin-1 (AQP1) in nasopharyngeal tumour and nontumour tissues.
METHOD: Thirty nasopharyngeal biopsy samples were collected and examined with both immunohistochemistry and real-time fluorescence quantitative polymerase chain reaction (RT-PCR) to detect the expression level of AQP1 in tissues.
RESULTS: Immunohistochemistry data suggested that AQP1 was expressed in both nasopharyngeal tumour and normal tissues, but tumour tissues were stained a lot stronger than nontumour tissues. RT-PCR analysis further confirmed the overexpression of AQP1 in tumour tissues; migrated tumour tissue had even higher expression.
CONCLUSION: The expression level of aquaporin-1 in nasopharyngeal cancer tissue could be involved in tumour migration.

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