Down-regulation of aquaporin-1 in intrahepatic cholangiocarcinoma is related to tumor progression and mucin expression

Decreased Expression of Alzheimer's Disease-Related Genes in Cancer May Contribute to the Inverse-Relationship-a Computational Study

Alzheimer's disease (AD) has been largely prevalent among the older population. With the increasing incidence of cancer over the years, scientists have explored the relationship between these two conditions which were formerly associated with aging. Interestingly, an inverse relationship between cancer and AD has been observed in large cohort studies which has garnered substantial interest. While this inverse relationship presents a fascinating scientific puzzle, there is limited data on the molecular mechanisms that govern this phenomenon. This study aims to investigate the fundamental molecular mechanisms driving the inverse association between AD and three common cancers: breast, prostate, and colorectal cancers. Gene expression data for AD were obtained from the Gene Expression Omnibus (GEO) repository, specifically the GSE122063 data set. Differentially expressed genes (DEGs) between AD and nondemented controls were identified using the GEO2R tool. Genes associated with breast, prostate, and colorectal cancer were obtained from the Genecards database. Shared genes between cancers and AD-upregulated genes were identified using the Venny 2.1 tool. The UALCAN analysis portal was used to evaluate the mRNA expression of shared genes in cancer types. The DAVID tool, ShinyGO and SRplotter tools were used for functional enrichment analyses and gene ontology annotations. We found 20 genes upregulated in AD but significantly downregulated in breast cancer, 11 significantly downregulated in prostate cancer and 5 genes downregulated in colon cancer. Key genes were involved in pathways related to muscle structure, DNA repair, protein stability, and gene expression regulation. Three (3) of these genes, AQP1, CRYAB, and HSPB2, were downregulated in all three cancers and may play an important role in reduced risk of cancer development while upregulated in AD. This study serves as a foundational effort to delve deeper into the molecular connections between AD and various cancer types, using the identified genes as a promising starting point for future experimental investigations to fully elucidate the mechanisms involved in the inverse interaction and protection of AD patients against cancer development.

The comprehensive potential of AQP1 as a tumor biomarker: evidence from kidney neoplasm cohorts, cell experiments and pan-cancer analysis

Aquaporin1 (AQP1) facilitates water transport. Its ability to be a biomarker at the pan-cancer level remains uninvestigated. We performed immunohistochemical staining on tissues from 370 individuals with kidney neoplasms to measure AQP1 expression. We utilized Kaplan-Meier survival analysis, Chi-square tests, and multivariate Cox regression analyses to assess the prognostic relevance of AQP1 expression. In the pan-cancer context, we explored AQP1's competing endogenous RNAs network, protein-protein interactions, genomic changes, gene set enrichment analysis (GSEA), the correlation of AQP1 expression with survival outcomes, drug sensitivity, drug molecular docking, tumor purity and immunity. AQP1 shRNA expressing 786-O cells were established. Cell proliferation was assessed by Cell Counting Kit-8 and colony formation. Transwell migration, invasion, and cell scratch assays were conducted. In our study, AQP1 expression was an independent protective factor for OS and PFS in renal cancer patients. AQP1 expression significantly correlated with survival outcomes in renal cancers, LGG, SARC, HNSC and UVM. PI-103 sensitivity was related to AQP1 expression and had potential binding cite with AQP1 protein. Knockdown of AQP1 reduced cell proliferation, migration and invasion. Our study uncovered AQP1 as a biomarker for favorable survival outcomes in renal cancers. Furthermore, the bioinformatic analysis promoted its implication in pan-cancer scope.

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.

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.

Understanding the Clinical Significance of MUC5AC in Biliary Tract Cancers

Biliary tract cancers (BTC) arise from biliary epithelium and include cholangiocarcinomas or CCA (including intrahepatic (ICC) and extrahepatic (ECC)) and gallbladder cancers (GBC). They often have poor outcomes owing to limited treatment options, advanced presentations, frequent recurrence, and poor response to available systemic therapy. Mucin 5AC (MUC5AC) is rarely expressed in normal biliary epithelium, but can be upregulated in tissues of benign biliary disease, premalignant conditions (e.g., biliary intraepithelial neoplasia), and BTCs. This mucin's numerous glycoforms can be divided into less-glycosylated immature and heavily-glycosylated mature forms. Reported MUC5AC tissue expression in BTC varies widely, with some associations based on cancer location (e.g., perihilar vs. peripheral ICC). Study methods were variable regarding cancer subtypes, expression positivity thresholds, and MUC5AC glycoforms. MUC5AC can be detected in serum of BTC patients at high concentrations. The hesitancy in developing MUC5AC into a clinically useful biomarker in BTC management is due to variable evidence on the diagnostic and prognostic value. Concrete conclusions on tissue MUC5AC are difficult, but serum detection might be relevant for diagnosis and is associated with poor prognosis. Future studies are needed to further the understanding of the potential clinical value of MUC5AC in BTC, especially regarding predictive and therapeutic value.

Human Aquaporins: Functional Diversity and Potential Roles in Infectious and Non-infectious Diseases

Aquaporins (AQPs) are integral membrane proteins and found in all living organisms from bacteria to human. AQPs mainly involved in the transmembrane diffusion of water as well as various small solutes in a bidirectional manner are widely distributed in various human tissues. Human contains 13 AQPs (AQP0-AQP12) which are divided into three sub-classes namely orthodox aquaporin (AQP0, 1, 2, 4, 5, 6, and 8), aquaglyceroporin (AQP3, 7, 9, and 10) and super or unorthodox aquaporin (AQP11 and 12) based on their pore selectivity. Human AQPs are functionally diverse, which are involved in wide variety of non-infectious diseases including cancer, renal dysfunction, neurological disorder, epilepsy, skin disease, metabolic syndrome, and even cardiac diseases. However, the association of AQPs with infectious diseases has not been fully evaluated. Several studies have unveiled that AQPs can be regulated by microbial and parasitic infections that suggest their involvement in microbial pathogenesis, inflammation-associated responses and AQP-mediated cell water homeostasis. This review mainly aims to shed light on the involvement of AQPs in infectious and non-infectious diseases and potential AQPs-target modulators. Furthermore, AQP structures, tissue-specific distributions and their physiological relevance, functional diversity and regulations have been discussed. Altogether, this review would be useful for further investigation of AQPs as a potential therapeutic target for treatment of infectious as well as non-infectious diseases.

Expression and Serum Levels of Mucin 5AC (MUC5AC) as a Biomarker for Cholangiocarcinoma: a Meta-analysis

AIM

The potential of biomarkers in detecting early cholangiocarcinoma (CCA) is facilitated by examining CCA-associated proteins from primary studies. One such protein is mucin 5AC (MUC5AC) but inconsistency of reported associations between its expression/serum levels and CCA prompts a meta-analysis to obtain more precise estimates.

METHODS

A literature search yielded 17 included articles where multiple data in some raised the number of studies to 22. We calculated pooled odds ratios (OR) and 95% confidence intervals from negative and positive readings of MUC5AC levels. Data were subgrouped by ethnicity, detection method, sample source, and cancer type.

RESULTS

Outcome in the overall analysis was non-significant but those in the subgroups were. Thus, significant associations (P < 0.001) indicating high MUC5AC levels were found in three subgroups: (i) Thai (OR 8.32) and (ii) serum (OR 4.52). Heterogeneity of these two outcomes (I² = 90-93%) was erased with outlier treatment (I² = 0%) which also modulated the pooled effects (OR 2.48-2.59). (iii) Immunoblot (OR 2.61) had low initial heterogeneity (I² = 2%). Robustness and significant tests for interaction (P_interaction = 0.01-0.02) improved MUC5AC associations with CCA in the Thai population.

CONCLUSIONS

Our pooled effect findings target the biomarker potential of MUC5AC to the Thai population.

Decreased expression of aquaporin 1 correlates with clinicopathological features of patients with cervical cancer

Purpose: We aimed to investigate the expression dynamics of Aquaporin 1 (AQP1) in cervical cancer and evaluate correlations among AQP1 levels and the clinicopathological features of patients with cervical cancer.

Patients and methods:AQP1 mRNA and protein levels in cervical cancer and adjacent normal tissues were evaluated by quantitative reverse-transcription PCR (qRT-PCR) and western blot. Immunohistochemistry (IHC) for AQP1 was performed with a tissue microarray of cervical cancer (containing 63 cases of squamous cell cervical cancers and 10 normal cervical tissues) to investigate clinicopathological outcomes. Cut-off scores for positive expression of AQP1 were determined by receiver operating characteristic analysis. The χ² test was used to analyze correlations among AQP1 expression and clinicopathological features of cervical cancer.

Results: The expression of AQP1 was decreased in the majority of cervical cancer tissues by qRT-PCR and western blot analysis. Positive expression of AQP1 was observed in 100% (10/10) of normal cervical tissues and in 42.86% (27/63) of cervical cancer tissues by IHC analysis. The cut-off score for positive expression of AQP1 was determined to be 45% of cancer cells. Decreased expression of AQP1 was correlated with clinicopathological features including; poor pathological grade (P=0.000), late International Federation of Gynecology and Obstetrics stage (P=0.008), and positive lymph nodes (P=0.002).

Conclusion: These data suggest that decreased expression of AQP1 correlated with progressive features in patients with cervical cancer. AQP1 levels may serve as a potential biomarker for the diagnosis of cervical cancer.

Different Prognostic Implications of Aquaporin-1 and Aquaporin-5 Expression among Different Histological Types of Ovarian Carcinoma

The aquaporins (AQPs) are a family of transmembrane water channel proteins that are distributed in various human tissues. Recent studies have suggested that AQP expression correlates with various aspects of cancer biology that determine the aggressiveness of different cancers. Ovarian carcinoma is one of the most lethal gynecological cancers. Some studies have suggested that AQPs are expressed in ovarian carcinoma, and are associated with cancer cell growth and migration. In this study, we immunohistochemically evaluated the expression of AQP1, 3, 5, and 9 in a total of 300 ovarian carcinomas using tissue microarrays. In our analyses of correlations between aquaporin expression and overall survival, high AQP5 expression was significantly associated with poorer prognosis (P = 0.029). For AQP1, the low expression group trended towards poorer prognosis than the high expression group, but the difference was not statistically significant. When ovarian carcinomas were divided by histological types, high AQP5 expression correlated with poorer prognosis in serous carcinoma (P = 0.015), and low AQP1 expression correlated with poorer prognosis in clear cell carcinomas (P = 0.0055). By contrast, high AQP1 expression correlated with poorer prognosis in mucinous carcinoma (P = 0.0001) and endometrioid carcinoma (P = 0.021). Our studies suggest that AQPs can be useful prognostic markers in ovarian carcinoma, but their correlation with prognosis depends on the histological type of ovarian carcinoma.

Intrahepatic Mass-Forming Cholangiocarcinoma: Relationship Between Computed Tomography Characteristics and Histological Subtypes

OBJECTIVE

The aim of this study was to determine the value of multi-detector row computed tomography (MDCT) in differentiating the small-duct (SD) and large-duct (LD) types of intrahepatic mass-forming cholangiocarcinomas (IMCCs) and predicting patient prognosis.

METHODS

The 4-phase MDCT image findings of 82 patients with surgically confirmed IMCCs (60 SD-type and 22 LD-type IMCCs) were compared between 2 types using univariate and multivariate analyses. Overall survival rates for 78 patients with available information were compared using the Kaplan-Meier method.

RESULTS

Arterial hyperenhancement, round or lobulated contour, and lack of bile duct encasement were significant MDCT features suggesting the SD type, and lymph node enlargement was significantly associated with the LD type (all P's < 0.05). The presence of those 3 SD-type-suggestive features (MDCT-suggested SD type) demonstrated high specificity (90.9% [20/22]) in differentiating the SD type. Patients of MDCT-suggested SD type without lymph node enlargement (n = 24) demonstrated significantly better overall survival than other groups.

CONCLUSIONS

Preoperative MDCT features of IMCCs can help differentiate the SD and LD types and predict patient prognosis.

Mechanisms of Aquaporin-Facilitated Cancer Invasion and Metastasis

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

Aquaporin 9 is down-regulated in hepatocellular carcinoma and its over-expression suppresses hepatoma cell invasion through inhibiting epithelial-to-mesenchymal transition

Aquaporin 9 (AQP9) is the main aquaglyceroporin in the liver. Few studies have been performed regarding the role of AQP9 in hepatocellular carcinoma (HCC). Here, we report the expression and function of AQP9 in HCC tissues and cell lines. We found that AQP9 mRNA and protein levels were down-regulated in HCC tissues and human hepatoma cell lines compared to the para-cancer normal liver tissues and normal hepatocyte line, respectively. In a human HCC SMMC-7721 cell line, over-expression of AQP9 suppressed cell invasion in vitro and xenograft tumor growth in vivo. AQP9 over-expression increased the expression of E-cadherin and decreased the expression of N-cadherin in SMMC-7721 cells and xenografted tumors, which was correlated with decreased levels of phosphoinositide 3-kinase (PI3K) and p-Akt. Conversely, using siRNA to knock down AQP9 over-expression could reverse the phenotype caused by AQP9 over-expression. Our findings suggest that AQP9 is down-regulated in hepatocellular carcinoma and its over-expression suppresses hepatoma cell invasion through inhibiting epithelial-to-mesenchymal transition.

Toward understanding the selective anticancer capacity of cold atmospheric plasma--a model based on aquaporins (Review)

Selectively treating tumor cells is the ongoing challenge of modern cancer therapy. Recently, cold atmospheric plasma (CAP), a near room-temperature ionized gas, has been demonstrated to exhibit selective anticancer behavior. However, the mechanism governing such selectivity is still largely unknown. In this review, the authors first summarize the progress that has been made applying CAP as a selective tool for cancer treatment. Then, the key role of aquaporins in the H2O2 transmembrane diffusion is discussed. Finally, a novel model, based on the expression of aquaporins, is proposed to explain why cancer cells respond to CAP treatment with a greater rise in reactive oxygen species than homologous normal cells. Cancer cells tend to express more aquaporins on their cytoplasmic membranes, which may cause the H2O2 uptake speed in cancer cells to be faster than in normal cells. As a result, CAP treatment kills cancer cells more easily than normal cells. Our preliminary observations indicated that glioblastoma cells consumed H2O2 much faster than did astrocytes in either the CAP-treated or H2O2-rich media, which supported the selective model based on aquaporins.

Expression of aquaporin-1, aquaporin-3, and aquaporin-5 correlates with nodal metastasis in colon cancer

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.

Transcriptome-wide signatures of tumor stage in kidney renal clear cell carcinoma: connecting copy number variation, methylation and transcription factor activity

BACKGROUND

Comparative analysis of expression profiles between early and late stage cancers can help to understand cancer progression and metastasis mechanisms and to predict the clinical aggressiveness of cancer. The observed stage-dependent expression changes can be explained by genetic and epigenetic alterations as well as transcription dysregulation. Unlike genetic and epigenetic alterations, however, activity changes of transcription factors, generally occurring at the post-transcriptional or post-translational level, are hard to detect and quantify.

METHODS

Here we developed a statistical framework to infer the activity changes of transcription factors by simultaneously taking into account the contributions of genetic and epigenetic alterations to mRNA expression variations.

RESULTS

Applied to kidney renal clear cell carcinoma (KIRC), the model underscored the role of methylation as a significant contributor to stage-dependent expression alterations and identified key transcription factors as potential drivers of cancer progression.

CONCLUSIONS

Integrating copy number, methylation, and transcription factor activity signatures to explain stage-dependent expression alterations presented a precise and comprehensive view on the underlying mechanisms during KIRC progression.

Bile duct adenoma and von Meyenburg complex-like duct arising in hepatitis and cirrhosis: pathogenesis and histological characteristics

Morphologic features and neoplastic potentials of bile duct adenoma (BDA) and von Meyenburg complex (VMC)-like duct arising in chronic liver disease were unknown. Thirty-five BDAs and 12 VMC-like duct lesions were observed in 39 cases with chronic liver disease. BDAs were divided into the EMA-cytoplasmic type (n = 14) and EMA-luminal type (n = 21). EMA-cytoplasmic BDA composed of a proliferation of cuboidal to low-columnar cells forming an open lumen with NCAM(+)/MUC6(-), resembling an interlobular bile duct. EMA-luminal BDA showed uniform cuboidal cells with narrow lumen, and NCAM(++)/MUC6(++), resembling a ductular reaction. VMC-like duct showed positive MUC1 expression and negative MUC6. The expression of S100P, glucose transporter-1 (GLUT-1) and insulin-like growth factor II mRNA-binding protein 3 (IMP-3) were not detected in three lesions. p16 expression was higher than those of the ductular reaction, and the Ki67 and p53 indexes were very low (<1.0%). Large-sized EMA-luminal BDA shows sclerotic stroma. We classified small nodular lesions of ductal or ductular cells in chronic hepatitis and cirrhosis into the following groups: BDA, interlobular bile duct type; BDA, ductular/peribiliary gland type; and VMC-like duct. They may be reactive proliferation rather than neoplastic lesions.

Key roles of aquaporins in tumor biology

Aquaporins are protein channels that facilitate the flow of water across plasma cell membranes in response to osmotic gradients. This review summarizes the evidence that aquaporins play key roles in tumor biology including tumor-associated edema, tumor cell migration, tumor proliferation and tumor angiogenesis. Aquaporin inhibitors may thus be a novel class of anti-tumor agents. However, attempts to produce small molecule aquaporin inhibitors have been largely unsuccessful. Recently, monoclonal human IgG antibodies against extracellular aquaporin-4 domains have become available and could be engineered to kill aquaporin-4 over-expressing cells in the malignant brain tumor glioblastoma. We conclude this review by discussing future directions in aquaporin tumor research. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Pathogenesis and classification of intrahepatic cholangiocarcinoma: different characters of perihilar large duct type versus peripheral small duct type

Intrahepatic cholangiocarcinomas (ICCs) are made up of heterogenous carcinomas arising from different anatomical sites of the liver. Two types of candidate stem/progenitor cells of the biliary tree are postulated to exist at the peribiliary glands for large bile ducts and at the canals of Hering for small ducts and hepatocytes. According to the recent observations, ICCs can be subclassified into two types: tumors involving the large bile ducts comparable in size to the intrahepatic second branches and composed of a tubular or papillary component with tall columnar epithelium, and tumors involving the smaller duct than segmental branches and composed of small tubules with cuboidal epithelium. Perihilar large duct type ICCs can be interpreted as arising from large bile duct type ICCs, and peripheral small duct type ICCs may arise from small bile duct type or ductular type ICCs. Chronic biliary inflammation induces neoplastic change of the large bile ducts and thereby progression to the perihilar large duct type ICC, which can be grossly classified into periductal filtrating type ICC and intraductal growth type ICC, while chronic hepatitis or cirrhosis induces mass-forming peripheral small duct type ICC. The different morphological and molecular features, including stromal components and tumor vasculature, support the hypothesis that perihilar large duct type ICCs and peripheral small duct type ICCs arise from different backgrounds, have different carcinogenetic pathways, and exhibit different biologic behaviors.

Participation of aquaporin-1 in vascular changes and remodeling in cirrhotic liver

The pathophysiology of arterial capillary proliferation accompanying fibrosis in human cirrhosis remains unclear. However, evidence regarding the molecules participating in the pathophysiological process has been accumulating. Water channel proteins known as aquaporins (AQP)s, notably AQP-1, appear to be involved in the arterial capillary proliferation in the cirrhotic liver.

Hypoxia-induced up-regulation of aquaporin-1 protein in prostate cancer cells in a p38-dependent manner

BACKGROUND/AIMS

Aquaporin-1 (AQP1) is a glycoprotein that mediates osmotic water transport, its expression has been found to correlate with tumour stage in some tumours. However, the mechanism by which AQP1 protein expression is regulated in tumor cells remains to be fully elucidated. We hypothesized that hypoxia might play an important role in AQP1 induction during tumorigenesis and at the late stages of tumor development.

METHODS

Isotonic and serum-free hypoxic models were used to investigate AQP1 expression in PC-3M human prostate cancer cells.

RESULTS

AQP1 expression was up-regulated by density-induced pericellular hypoxia and cobalt(II) chloride (CoCl(2))-induced hypoxia at the transcriptional level. Moreover, phosphorylation of p38 mitogen-activated protein kinase (MAPK) was induced by density-induced pericellular hypoxia and CoCl(2)-induced hypoxia, specific inhibitors of p38 MAPK could concentration-dependently block those effects of hypoxia on AQP1 expression. Intracellular calcium ion (Ca(2+)) and protein kinase C (PKC) were shown to be responsible for the activation of p38 MAPK pathway. In addition, AQP1 induction in dense cultures was dependent on lowered oxygen (O(2)) tension. In high cell density culture, certain secretory proteins might induce AQP1 expression indirectly.

CONCLUSION

These findings suggest that AQP1 could be induced by hypoxia at transcription level, and the regulation of AQP1 in PC-3M cells is dependent on calcium, PKC and p38 MAPK, as well as low oxygen tension.

Aquaporin-3 positively regulates matrix metalloproteinases via PI3K/AKT signal pathway in human gastric carcinoma SGC7901 cells

BACKGROUND

matrix metalloproteinases (MMPs) are produced by tumor cells, so they may be associated with tumor progression including invasion, migration, angiogenesis and metastasis. Aquaporin-3 (AQP3) also plays a critical role in gastric cancer cell migration and proliferation.

METHODS

In this study, AQP3 was silenced or over-expressed in SGC7901 cells.

RESULTS

We found a significant decrease in MT1-MMP, MMP-2, and MMP-9 expression after AQP3 knockdown, and a significant increase in MT1-MMP, MMP-2, and MMP-9 expression after AQP3 over-expression in SGC7901 cells. We also found that AQP3 silence led to a significant decrease of phosphorylation of ser473 in AKT in SGC7901 cells.

CONCLUSION

Our findings showed that AQP3 might positively regulate MMPs proteins expression through PI3K/AKT signal pathway in human gastric carcinoma SGC7901 cells.

Intrahepatic cholangiocarcinoma progression: prognostic factors and basic mechanisms

In this review, we will examine various molecular biomarkers for their potential to serve as independent prognostic factors for predicting survival outcome in postoperative patients with progressive intrahepatic cholangiocarcinoma. Specific rodent models of intrahepatic cholangiocarcinoma that mimic relevant cellular, molecular, and clinical features of the human disease are also described, not only in terms of their usefulness in identifying molecular pathways and mechanisms linked to cholangiocarcinoma development and progression, but also for their potential value as preclinical platforms for suggesting and testing novel molecular strategies for cholangiocarcinoma therapy. Last, recent studies aimed at addressing the role of desmoplastic stroma in promoting intrahepatic cholangiocarcinoma progression are highlighted in an effort to underline the potential value of targeting tumor stromal components together with that of cholangiocarcinoma cells as a novel therapeutic option for this devastating cancer.

Construction of the specific MUC5AC-siRNA expression plasmid and effect of siRNA on proliferation and apoptosis in human bile duct cancer line HCCC-9810

AIM: To observe specific siRNA silencing effect on Mucin-5 subtype AC gene in human intrahepatic cholangiocarcinoma cell line HCCC-9810 as well as to investigate the influence on proliferation and apoptosis after silencing the Mucin-5 subtype AC gene.

METHODS: Three pairs of specific MUC5AC-siRNA were designed and synthesized through transcription in vitro. Three different siRNA expression plasmids (pRNAT-U6.1/Neo-MUC5AC-siRNA1/2/3) were constructed by gene recombination. Then three stable expression plasmids and the comparison plasmid (empty plasmid-transfected control) were transfected into HCCC-9810 by liposome-mediated transfection. Transfection efficiency was evaluated by nonspecific small molecular siRNA (fluorescent conjugate). MUC5AC-mRNA level was detected by RT-PCR. Expression of Mucin-5 subtype AC was investigated by immunohistochemical SABC method. Cell apoptosis and proliferation were analyzed by flow cytometry and MTT, respectively.

RESULTS: The results of gene sequencing indicated that the pRNAT-U6.1/Neo-MUC5AC-siRNA1/2/3 was successfully constructed. After the transfection, the efficiency of fluorescent protein expression reached 28.57%; the results of RT-PCR and immunocytochemistry showed that constructed plasmids down-regulated mRNA and protein of Mucin-5 subtype AC at 48 h after transfection. The results of MTT indicated that the growth of HCCC-9810 was obviously inhibited after silencing the Mucin-5 subtype AC gene. Apoptosis was induced in the tumor cells after suppressing the expression of Mucin-5 subtype AC gene by flow cytometry.

CONCLUSION: Three different stable expression plasmids of siRNA specific for Mucin-5 subtype AC gene obviously inhibit the expression at MUC5AC-mRNA and protein level. The blockage of Mucin-5 subtype AC gene expression in HCCC-9810 cells shows significant effect on cell apoptosis and proliferation.

Expression of aquaporin1, 3, and 4, NKCC1, and NKCC2 in the human endolymphatic sac

OBJECTIVE

To locate aquaporin (AQP) 1, 3, and 4, Na-K-2Cl cotransporter (NKCC) 1 and 2 in the human endolymphatic sac (ES).

METHODS

A sample of human ES was harvested during the removal of vestibular schwannoma via the translabyrinthine approach. The sample was immediately fixed in 4% paraformaldehyde and embedded in OCT compound. Immunohistochemistry was performed with AQP1, 3, and 4, NKCC1, and NKCC2 polyclonal antibodies.

RESULTS

AQP1, AQP3, and NKCC2 were strongly expressed in the epithelial layer of the ES. AQP4 and NKCC1 were weakly expressed in the epithelial layer of the ES.

CONCLUSIONS

As it is impossible to perform quantitative analysis based on the fluorescence intensity of each immunoreactivity, we have presented the existence of AQP1, 3, and 4, NKCC1, and NKCC2 in the ES. The expression of NKCC1 and 2 indicated that the ES may have both secretory and adsorptive functions to maintain the homeostasis of endolymph.

Aquaporins--new players in cancer biology

The aquaporins (AQPs) are small, integral-membrane proteins that selectively transport water across cell plasma membranes. A subset of AQPs, the aquaglyceroporins, also transport glycerol. AQPs are strongly expressed in tumor cells of different origins, particularly aggressive tumors. Recent discoveries of AQP involvement in cell migration and proliferation suggest that AQPs play key roles in tumor biology. AQP1 is ubiquitously expressed in tumor vascular endothelium, and AQP1-null mice show defective tumor angiogenesis resulting from impaired endothelial cell migration. AQP-expressing cancer cells show enhanced migration in vitro and greater local tumor invasion, tumor cell extravasation, and metastases in vivo. AQP-dependent cell migration may involve AQP-facilitated water influx into lamellipodia at the front edge of migrating cells. The aquaglyceroporin AQP3, which is found in normal epidermis and becomes upregulated in basal cell carcinoma, facilitates cell proliferation in different cell types. Remarkably, AQP3-null mice are resistant to skin tumorigenesis by a mechanism that may involve reduced tumor cell glycerol metabolism and ATP generation. Together, the data suggest that AQP expression in tumor cells and tumor vessels facilitates tumor growth and spread, suggesting AQP inhibition as a novel antitumor therapy.