c-Met upregulates aquaporin 3 expression in human gastric carcinoma cells via the ERK signalling pathway

Aquaporin-3 is down-regulated by LMP1 in nasopharyngeal carcinoma cells to regulate cell migration and affect EBV latent infection

Epstein-Barr virus (EBV) infection has a strong correlation with the development of nasopharyngeal carcinoma (NPC). Aquaporin 3 (AQP3), a member of the aquaporin family, plays an important role in tumor development, especially in epithelial-mesenchymal transition. In this study, the expression of AQP3 in EBV-positive NPC cells was significantly lower than that in EBV-negative NPC cells. Western blot and qRT-PCR analysis showed that LMP1 down-regulated the expression of AQP3 by activating the ERK pathway. Cell biology experiments have confirmed that AQP3 affects the development of tumor by promoting cell migration and proliferation in NPC cells. In addition, AQP3 can promote the lysis of EBV in EBV-positive NPC cells. The inhibition of AQP3 expression by EBV through LMP1 may be one of the mechanisms by which EBV maintains latent infection-induced tumor progression.

SCFFBXW5-mediated degradation of AQP3 suppresses autophagic cell death through the PDPK1-AKT-MTOR axis in hepatocellular carcinoma cells

AQP3 (aquaporin 3 (Gill blood group)), a member of the AQP family, is an aquaglyceroporin which transports water, glycerol and small solutes across the plasma membrane. Beyond its role in fluid transport, AQP3 plays a significant role in regulating various aspects of tumor cell behavior, including cell proliferation, migration, and invasion. Nevertheless, the underlying regulatory mechanism of AQP3 in tumors remains unclear. Here, for the first time, we report that AQP3 is a direct target for ubiquitination by the SCFFBXW5 complex. In addition, we revealed that downregulation of FBXW5 significantly induced AQP3 expression to prompt macroautophagic/autophagic cell death in hepatocellular carcinoma (HCC) cells. Mechanistically, AQP3 accumulation induced by FBXW5 knockdown led to the degradation of PDPK1/PDK1 in a lysosomal-dependent manner, thus inactivating the AKT-MTOR pathway and inducing autophagic death in HCC. Taken together, our findings revealed a previously undiscovered regulatory mechanism through which FBXW5 degraded AQP3 to suppress autophagic cell death via the PDPK1-AKT-MTOR axis in HCC cells.Abbreviation: BafA1: bafilomycin A1; CQ: chloroquine; CRL: CUL-Ring E3 ubiquitin ligases; FBXW5: F-box and WD repeat domain containing 5; HCC: hepatocellular carcinoma; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; 3-MA: 3-methyladenine; PDPK1/PDK1: 3-phosphoinositide dependent protein kinase 1; RBX1/ROC1: ring-box 1; SKP1: S-phase kinase associated protein 1; SCF: SKP1-CUL1-F-box protein.

Aquaporin-mediated dysregulation of cell migration in disease states

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

Non-Transport Functions of Aquaporins

Although it has been more than 20 years since the first aquaporin was discovered, the specific functions of many aquaporins are still under investigation, because various mice lacking aquaporins have no significant phenotypes. And in many studies, the function of aquaporin is not directly related to its transport function. Therefore, this chapter will focus on some unexpected functions of aquaporins, such the decreased tumor angiogenesis in AQP1 knockout mice, and AQP1 promotes cell migration, possibly by accelerating the water transport in lamellipodia of migrating cells. AQP transports glycerol, and water regulates glycerol content in epidermis and fat, thereby regulating skin hydration/biosynthesis and fat metabolism. AQPs may also be involved in neural signal transduction, cell volume regulation, and organelle physiology. AQP1, AQP3, and AQP5 are also involved in cell proliferation. In addition, AQPs have also been reported to play roles in inflammation in various tissues and organs. The functions of these AQPs may not depend on the permeability of small molecules such as water and glycerol, suggesting AQPs may play more roles in different biological processes in the body.

KLF5-mediated aquaporin 3 activated autophagy to facilitate cisplatin resistance of gastric cancer

BACKGROUND

Resistance to chemotherapeutic drugs limits the control of gastric cancer (GC) development. The study intended to probe into the mechanism of aquaporin 3 (AQP3) on the chemoresistance of GC.

METHODS

Cisplatin (CDDP)-resistant cells were constructed. Parental AGS and HGC-27 cells and their respective CDDP-resistant cells were transfected with AQP3 overexpression plasmid, AQP3 short hairpin RNA (sh-AQP3) and sh-Kruppel-like factor 5 (shKLF5). The expressions of AQP3 and factors related to autophagy (LC3 I, LC3 II, Atg5, Beclin-1, p62)/epithelial-mesenchymal transition (EMT; E-cadherin and snail) were assessed by Western blot and qRT-PCR. Cell counting kit-8 assay was adopted to test cell viability and half maximal inhibitory concentration (IC 50) was determined. Transwell assay was used for the examination of cell migration and invasion. The regulatory relationship of AQP3 and KLF5 was tested by chromatin immunoprecipitation (ChIP) and dual luciferase reporter assays.

RESULTS

AQP3 was highly-expressed in GC cells and its level was even higher in CDDP-resistant GC cells. AQP3 silencing inhibited viability, autophagy and EMT in CDDP-resistant GC cells, while AQP3 overexpression had the opposite effect. KLF5 positively modulated AQP3 in GC cells resistant to CDDP. KLF5 knockdown reversed AQP3-induced autophagy, viability, migration, invasion and EMT in CDDP-resistant GC cells.

CONCLUSION

KLF5-modulated AQP3 activated autophagy to facilitate the resistance of GC to CDDP.

Clinical value and molecular mechanism of AQGPs in different tumors

Aquaglyceroporins (AQGPs), including AQP3, AQP7, AQP9, and AQP10, are transmembrane channels that allow small solutes across biological membranes, such as water, glycerol, H₂O₂, and so on. Increasing evidence suggests that they play critical roles in cancer. Overexpression or knockdown of AQGPs can promote or inhibit cancer cell proliferation, migration, invasion, apoptosis, epithelial-mesenchymal transition and metastasis, and the expression levels of AQGPs are closely linked to the prognosis of cancer patients. Here, we provide a comprehensive and detailed review to discuss the expression patterns of AQGPs in different cancers as well as the relationship between the expression patterns and prognosis. Then, we elaborate the relevance between AQGPs and malignant behaviors in cancer as well as the latent upstream regulators and downstream targets or signaling pathways of AQGPs. Finally, we summarize the potential clinical value in cancer treatment. This review will provide us with new ideas and thoughts for subsequent cancer therapy specifically targeting AQGPs.

The SKA3-DUSP2 Axis Promotes Gastric Cancer Tumorigenesis and Epithelial-Mesenchymal Transition by Activating the MAPK/ERK Pathway

Background: Spindle and kinetochore-related complex subunit 3 (SKA3), a member of the SKA family of proteins, is associated with the progression of multiple cancers. However, the role of SKA3 in gastric cancer has not been studied.

Methods: The expression levels of SKA3 and dual-specificity phosphatase 2 (DUSP2) proteins were detected by immunohistochemistry. The effects of SKA3 and DUSP2 on the proliferation, migration, invasion, adhesion, and epithelial-mesenchymal transition of gastric cancer were studied in vitro and in vivo.

Results: Immunohistochemical analysis of 164 cases of gastric cancer revealed that high expression of SKA3 was negatively correlated with DUSP2 expression and related to N stage, peritoneal metastasis, and poor prognosis. In vitro studies showed that silencing SKA3 expression inhibited the proliferation, migration, invasion, adhesion and epithelial-mesenchymal transition of gastric cancer. In vivo experiments showed that silencing SKA3 inhibited tumor growth and peritoneal metastasis. Mechanistically, SKA3 negative regulates the tumor suppressor DUSP2 and activates the MAPK/ERK pathway to promote gastric cancer.

Conclusion: Our results indicate that the SKA3-DUSP2-ERK1/2 axis is involved in the regulation of gastric cancer progression, and SKA3 is a potential therapeutic target for gastric cancer.

Receptor Tyrosine Kinases and Their Signaling Pathways as Therapeutic Targets of Curcumin in Cancer

Receptor tyrosine kinases (RTKs) are transmembrane cell-surface proteins that act as signal transducers. They regulate essential cellular processes like proliferation, apoptosis, differentiation and metabolism. RTK alteration occurs in a broad spectrum of cancers, emphasising its crucial role in cancer progression and as a suitable therapeutic target. The use of small molecule RTK inhibitors however, has been crippled by the emergence of resistance, highlighting the need for a pleiotropic anti-cancer agent that can replace or be used in combination with existing pharmacological agents to enhance treatment efficacy. Curcumin is an attractive therapeutic agent mainly due to its potent anti-cancer effects, extensive range of targets and minimal toxicity. Out of the numerous documented targets of curcumin, RTKs appear to be one of the main nodes of curcumin-mediated inhibition. Many studies have found that curcumin influences RTK activation and their downstream signaling pathways resulting in increased apoptosis, decreased proliferation and decreased migration in cancer both in vitro and in vivo. This review focused on how curcumin exhibits anti-cancer effects through inhibition of RTKs and downstream signaling pathways like the MAPK, PI3K/Akt, JAK/STAT, and NF-κB pathways. Combination studies of curcumin and RTK inhibitors were also analysed with emphasis on their common molecular targets.

Polyphenols from Broussonetia papyrifera Induce Apoptosis of HepG2 Cells via Inactivation of ERK and AKT Signaling Pathways

The extract of Broussonetia papyrifera has been proved to have antitumor activity. However, the underlying mechanism remains unclear. This study aimed to elucidate the mechanism of apoptosis of HepG2 cells induced by polyphenols from Broussonetia papyrifera (PBPs). The results revealed that PBPs inhibited the proliferation of HepG2 cells in a dose-dependent and time-dependent manner. Flow cytometry analysis showed that PBPs increased the apoptosis ratio of HepG2 cells significantly. PBPs increased intracellular reactive oxygen species (ROS) production and decreased intracellular superoxide dismutase (SOD) level of HepG2 cells. PBPs induced cell cycle arrest at G1 phase. Western blotting showed that PBPs upregulated the ratio of Bax/Bcl-2 and the expression level of Caspase-3, and activated p53 in HepG2 cells. The inhibition of proliferative relative signals (protein kinase B, PKB/AKT) and survival relative signals (extracellular signal-regulated kinase, ERK) were also observed in PBP-treated HepG2 cells. Our findings suggest that apoptosis of HepG2 cells induced by PBPs is mitochondria-mediated via inactivation of ERK and AKT signaling pathways.

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

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

Aquaporins in health and disease

Aquaporins (AQPs) are transmembrane channel proteins that mainly facilitate the water translocation through the plasma cell membrane. For several years these proteins have been extensively examined for their biologic role in health and their potential implication in different diseases. Technological improvements associated with the methods employed to evaluate the functions of the AQPs have provided us with significant new knowledge. In this chapter, we will examine the role of AQPs in health and disease based on the latest currently available evidence.

Hypoxia-Induced Aquaporin-3 Changes Hepatocellular Carcinoma Cell Sensitivity to Sorafenib by Activating the PI3K/Akt Signaling Pathway

Purpose

Hypoxia-induced changes are primarily activated in patients with hepatocellular carcinoma (HCC) and long-term sorafenib exposure, thereby reducing the sensitivity to the drug. Aquaporin-3 (AQP3), a member of the aquaporin family, is a hypoxia-induced substance that affects the chemosensitivity of non-hepatocellular tumors. However, its expression and role in the sensitivity of hypoxic HCC cells to sorafenib-induced apoptosis remain unclear. The purpose of this study was to detect changes in AQP3 expression in hypoxic HCC cells and to determine whether these changes alter the sensitivity of these cells to sorafenib.

Materials and Methods

Huh7 and HepG2 hypoxic cell models were established and AQP3 expression was detected using quantitative real-time polymerase chain reaction (qPCR) and Western blotting. Furthermore, the role of AQP3 in cell sensitivity to sorafenib was evaluated via flow cytometry, Western blotting, and a CCK-8 assay.

Results

The results of qPCR and Western blotting showed that AQP3 was overexpressed in the Huh7 and HepG2 hypoxic cell models. Furthermore, AQP3 protein levels were positively correlated with hypoxia-inducible factor-1α (HIF-1α) levels. Compared with cells transfected with lentivirus-GFP (Lv-GFP), hypoxic cells transfected with lentivirus-AQP3 (Lv-AQP3) were less sensitive to sorafenib-induced apoptosis. However, the sensitivity to the drug increased in cells transfected with lentivirus-AQP3RNAi (Lv-AQP3RNAi). Akt and Erk phosphorylation was enhanced in Lv-AQP3-transfected cells. Compared with UO126 (a Mek1/2 inhibitor), LY294002 (a PI3K inhibitor) attenuated the AQP3-induced insensitivity to sorafenib observed in hypoxic cells transfected with Lv-AQP3. Combined with LY294002-treated cells, hypoxic cells transfected with Lv-AQP3RNAi were more sensitive to sorafenib.

Conclusion

The study results show that AQP3 is a potential therapeutic target for improving the sensitivity of hypoxic HCC cells to sorafenib.

Aquaporin 3 maintains the stemness of CD133+ hepatocellular carcinoma cells by activating STAT3

An increasing interest in liver cancer stemness arises owing to its aggressive behavior and poor prognosis. CD133, a widely known liver cancer stem cell marker, plays critical roles in the maintenance of liver cancer stemness. Thus, exploring the regulatory mechanism of CD133 expression is significant. In the present study, we proved the carcinogenesis roles of aquaporin 3 (AQP3) in hepatocellular carcinoma (HCC) and demonstrated that AQP3 promotes the stem cell-like properties of hepatoma cells by regulating CD133 expression. In addition, AQP3 promoted the stimulation and nuclear translocation of signal transducer and activator of transcription 3 (STAT3) with a subsequent increase in the level of CD133 promoter-acetylated histone H3. This phenomenon accelerated CD133 transcription. Next, whether AQP3 acted as an oncogenic gene in HCC and maintained the stemness of CD133+ hepatoma cells were elucidated; also, a novel mechanism underlying the AQP3/STAT3/CD133 pathway in HCC was deduced.

LMP2A induces DNA methylation and expression repression of AQP3 in EBV-associated gastric carcinoma

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) is a unique type of gastric carcinomas that promoter hypermethylation of tumor-related genes is extremely frequent to be found. Aquaporin 3 (AQP3) is a small membrane transport protein that plays a crucial role in cancer progression and metastasis. However, there is no experimental study on the expression of AQP3 in EBVaGC and the regulation mechanism of EBV on AQP3. In this study, the loss of AQP3 was contributed by the hypermethylation status of AQP3 promoter in EBVaGC which was caused by elevated expression of DNMT3a. In addition, stable and transient transfection system in SGC7901 showed that viral latent membrane protein 2A (LMP2A) activated phosphorylated ERK and up-regulated DNMT3a. Taken together, LMP2A induced the phosphorylation of ERK, which activated DNMT3a transcription and caused AQP3 expression loss through CpG island methylation of AQP3 promoter in EBVaGC.

Lnc-TALC promotes O6-methylguanine-DNA methyltransferase expression via regulating the c-Met pathway by competitively binding with miR-20b-3p

Long noncoding RNAs (lncRNAs) have emerged as new regulatory molecules implicated in diverse biological processes, including therapeutic resistance. However, the mechanisms underlying lncRNA-mediated temozolomide (TMZ) resistance in glioblastoma (GBM) remain largely unknown. To illustrate the role of lncRNA in TMZ resistance, we induce TMZ-resistant GBM cells, perform a lncRNA microarray of the parental and TMZ-resistant cells, and find an unreported lncRNA in GBM, lnc-TALC (temozolomide-associated lncRNA in glioblastoma recurrence), correlated with TMZ resistance via competitively binding miR-20b-3p to facilitate c-Met expression. A phosphorylated AKT/FOXO3 axis regulated lnc-TALC expression in TMZ-resistant GBM cells. Furthermore, lnc-TALC increased MGMT expression by mediating the acetylation of H3K9, H3K27 and H3K36 in MGMT promoter regions through the c-Met/Stat3/p300 axis. In clinical patients, lnc-TALC is required for TMZ resistance and GBM recurrence. Our results reveal that lnc-TALC in GBM could serve as a therapeutic target to overcome TMZ resistance, enhancing the clinical benefits of TMZ chemotherapy.

Temozolomide resistance in glioblastoma is associated with MGMT overexpression. Here, the authors identify a lncRNA that is a competitive endogenous RNA for miR-20b-3p, which causes c-Met activation to modulate acetylation of histone H3 on MGMT promoter through Stat3/p300 complex to increase MGMT expression and temozolomide resistance.

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

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

MicroRNA-449a suppresses hepatocellular carcinoma cell growth via G1 phase arrest and the HGF/MET c-Met pathway

BACKGROUND

Accumulating evidence demonstrates that microRNAs (miRNAs) play essential roles in tumorigenesis and cancer progression of hepatocellular carcinoma (HCC). Average targets of a miRNA were more than 100. And one miRNA may act in tumor via regulating several targets. The present study aimed to explore more potential targets of miR-449a by proteomics technology and further uncover the role of miR-449a in HCC tumorigenesis.

METHODS

Technologies such as iTRAQ-based quantitative proteomic were used to investigate the effect of miR-449a on HCC. The expression of c-Met and miR-449a was detected by qRT-PCR in HCC samples. Gain- and loss-of-function experiments were performed to identify the function and potential target of miR-449a in HCC cells.

RESULTS

In HCC, miR-449a was significantly downregulated, while c-Met was upregulated concurrently. Quantitative proteomics and luciferase reporter assay identified c-Met as a direct target of miR-449a. Moreover, miR-449a inhibited HCC growth not only by targeting CDK6 but also by suppressing c-Met/Ras/Raf/ERK signaling pathway. Furthermore, the inhibition of c-Met expression with a specific siRNA significantly inhibited cells growth and deregulated the ERK pathway in HCC.

CONCLUSION

The tumor suppressor miR-449a suppresses HCC tumorigenesis by repressing the c-Met/ERK pathway.

Involvement of Aryl Hydrocarbon Receptor and Aryl Hydrocarbon Receptor Repressor in Helicobacter Pylori-related Gastric Pathogenesis

Background: Persistent Helicobacter pylori (H. pylori) infection leads to various gastric diseases. Multiple studies have demonstrated that aryl hydrocarbon receptor (AHR) plays roles in the antibacterial response and aryl hydrocarbon receptor repressor (AHRR) is downregulated in stomach cancer. However, the role of AHR or AHRR in H. pylori-related gastric diseases remains unclear. Aims: To investigate whether AHR or AHRR is involved in H. pylori-related gastric diseases. Methods: Patients with gastritis or gastric adenocarcinoma were enrolled randomly, and gastric tissue specimens were diagnosed pathologically. AHR, AHRR, and H. pylori infection status in tissues were detected by immunohistochemistry. Human gastric cells were cocultured with H. pylori. siRNAs were used to silence AHR or AHRR, and a C57bl/6 mouse model colonized by H. pylori was established. Protein expression was determined by western blotting analysis, and TNF, IL-8 and IL-1β in cell supernatants were measured by ELISA. Results: AHR and AHRR were expressed in gastritis tissues and gastric cancer tissues without H. pylori infection, and principally located in the cytoplasm and nucleus. AHR expression was significantly correlated with AHRR expression in gastric tissues without H. pylori infection (P=0.008). However, their expressions were negatively correlated with H. pylori infection status. H. pylori coculture inhibited AHR and AHRR expression in stomach mucosa in vitro and in vivo. Gastric cells produced more TNF, IL-8 and IL-1β when AHR or AHRR was silenced. Conclusions: This preliminary study indicates that AHR and AHRR may be involved in H. pylori-related gastric pathogenesis, and helps toward understanding of inflammation-initiated carcinogenesis of gastric cancer.

Downregulation of aquaporin 3 inhibits cellular proliferation, migration and invasion in the MDA-MB-231 breast cancer cell line

Aquaporins are membrane proteins that regulate cellular water flow. Recently, aquaporins have been proposed as mediators of cancer cell biology. A subset of aquaporins, referred to as aquaglyceroporins are known to facilitate the transport of glycerol. The present study describes the effect of gene knockdown of the aquaglyceroporin AQP3 on MDA-MB-231 breast cancer cell proliferation, migration, invasion, adherence and response to the chemotherapeutic agent 5-fluorouracil. shRNA mediated AQP3 gene knockdown induced a 28% reduction in cellular proliferation (P<0.01), a 39% decrease in migration (P<0.0001), a 24% reduction in invasion (P<0.05) and a 25% increase in cell death at 100 µM 5-FU (P<0.01). Analysis of cell permeability to water and glycerol revealed that MDA-MB-231 cells with knocked down AQP3 demonstrated a modest decrease in water permeability (17%; P<0.05) but a more marked decrease in glycerol permeability (77%; P<0.001). These results suggest that AQP3 has a role in multiple aspects of breast cancer cell pathophysiology and therefore represents a novel target for therapeutic intervention.

MicroRNA-129-5p Regulates Glycolysis and Cell Proliferation by Targeting the Glucose Transporter SLC2A3 in Gastric Cancer Cells

Tumor cells increase their glucose consumption through aerobic glycolysis to manufacture the necessary biomass required for proliferation, commonly known as the Warburg effect. Accumulating evidences suggest that microRNAs (miRNAs) interact with their target genes and contribute to metabolic reprogramming in cancer cells. By integrating high-throughput screening data and the existing miRNA expression datasets, we explored the roles of candidate glycometabolism-regulating miRNAs in gastric cancer (GC). Subsequent investigation of the characterized miRNAs indicated that miR-129-5p inhibits glucose metabolism in GC cells. miRNA-129-5p directly targets the 3′-UTR of SLC2A3, thereby suppressing glucose consumption, lactate production, cellular ATP levels, and glucose uptake of GC cells. In addition, the PI3K-Akt and MAPK signaling pathways are involved in the effects of the miR-129-5p/SLC2A3 axis, regulating GC glucose metabolism and growth. These results reveal a novel role of the miR-129-5p/SLC2A3 axis in reprogramming the glycometabolism process in GC cells and indicate a potential therapeutic target for the treatment of this disease.

Aquaporin 3 promotes the stem-like properties of gastric cancer cells via Wnt/GSK-3β/β-catenin pathway

Cancer stem cells (CSCs) are believed to contribute to the tumor growth in gastric carcinoma (GC), a common lethal malignancy. This study investigated the effect of aquaporin 3 (AQP3) on stem-like properties of human GC cells. Elevated AQP3 expression was associated with CD44 expression in human GC specimens. Expression of AQP3 and that of CD44 positively correlated with Lauren classification, lymph node metastasis, and lymphovascular invasion. Altering the AQP3 expression had pronounced effects on the tumorigenic potential and self-renewal capacity of the gastric cancer cell lines SGC7901, MGC803, and AGS, both in vitro and in vivo. Overexpression of AQP3 induced CD44 expression and activation of the β-catenin signaling pathway, whereas silencing AQP3 expression using short hairpin RNA had the opposite effect. Furthermore, pharmacological inhibition of GSK-3β using LiCl impaired the effect of AQP3 knockdown in CSCs, whereas the inhibition of the Wnt/β-catenin pathway by XAV939 blocked the effect of AQP3 overexpression. These results demonstrate that AQP3 promotes stem-like properties of human GC cells by activating the Wnt/GSK-3β/β-catenin signaling pathway.

Identification of AQP3 and CD24 as biomarkers for carcinogenesis of gastric intestinal metaplasia

Gastric intestinal metaplasia (GIM) is a precancerous gastric carcinoma (GC) lesion with pivotal roles in carcinogenesis. CD24, LGR5 and Ki67 are expressed in GIM; we previously demonstrated that aquaporin 3 (AQP3) is expressed in goblet cells and is positively correlated with GIM severity. However, the relationships of AQP3 with GIM classification and with other proteins, and their roles in the transition from GIM to gastric carcinoma (GC) remain unknown. Sixteen patients with intestinal-type GC were enrolled in this study. GIM was determined according to the updated Sydney system; GIM classification was determined via HID-AB staining, and AQP3, CD24, LGR5 and Ki67 expression were determined by immunohistochemistry. Type III GIM was more prevalent around the GC and displayed a positive association with GIM severity. CD24 was found in GIM, but LGR5 and Ki67 were found in tissues regardless of GIM. AQP3 expression showed significant correlation to type III GIM. CD24 expression was correlated with the marked GIM and incomplete GIM, while LGR5 expression decreased with GIM aggravation and did not have relationship with classification of GIM. However, Ki67 presented no association with GIM grade or classification. These observations identify AQP3 and CD24 as biomarkers for carcinogenesis of GIM, and may provide a precise strategy for screening at-risk candidates with GIM.

Aquaporin 3 facilitates tumor growth in pancreatic cancer by modulating mTOR signaling

Aquaporins (AQP) have been demonstrated to be dysregulated in many human cancers and is thought to be involved in pancreatic carcinogenesis and progression. However, the oncogenic roles and underlying mechanism of AQP in pancreatic ductal adenocarcinoma (PDAC) remain largely unknown. In this study, by data mining of TCGA dataset and CCLE database, we identified that AQP3 is the major AQP expressed in PDAC. Then, the microRNA-874, was demonstrated to be a key regulator of AQP3 expression in PDAC cells. Genetic silencing of AQP3 expression had pronounced effects on cell proliferation and apoptosis of the PDAC cell lines BXPC3 and HPAFII. Introduction of microRNA-874 suppressed cell proliferation and promoted cell apoptosis, whereas inhibition of microRNA-874 had the opposite effect. Mechanistically, by a large-scale proteomic analysis, we revealed that AQP3 was significantly associated the activity of mTOR signaling. Moreover, modulation of AQP3 or microRNA-874 altered mTOR activity as demonstrated by the phosphorylation level of mTOR and its downstream target S6. Taken together, our data, as a proof of principle, suggest that AQP3 can promote tumor growth of pancreatic cancer cells by activating the Mtor signaling pathway and provide a potential therapeutic target in the treatment of PDAC.

Ion channels or aquaporins as novel molecular targets in gastric cancer

Gastric cancer (GC) is a common disease with few effective treatment choices and poor prognosis, and has the second-highest mortality rates among all cancers worldwide. Dysregulation and/or malfunction of ion channels or aquaporins (AQPs) are common in various human cancers. Furthermore, ion channels are involved in numerous important aspects of the tumor aggressive phonotype, such as proliferation, cell cycle, apoptosis, motility, migration, and invasion. Indeed, by localizing in the plasma membrane, ion channels or AQPs can sense and respond to extracellular environment changes; thus, they play a crucial role in cell signaling and cancer progression. These findings have expanded a new area of pharmaceutical exploration for various types of cancer, including GC. The involvement of multiple ion channels, such as voltage-gated potassium and sodium channels, intracellular chloride channels, ‘transient receptor potential’ channels, and AQPs, which have been shown to facilitate the pathogenesis of other tumors, also plays a role in GC. In this review, an overview of ion channel and aquaporin expression and function in carcinogenesis of GC is presented. Studies of ion channels or AQPs will advance our understanding of the molecular genesis of GC and may identify novel and effective targets for the clinical application of GC.

Aquaporin 3 facilitates chemoresistance in gastric cancer cells to cisplatin via autophagy

Cisplatin (cDDP) remains one of the first-line chemotherapeutic agents for gastric cancer (GC) treatment, and resistance to cDDP is the major limitation in its clinical application. Mechanisms of cDDP resistance have been shown to be varied and complicated. Aquaporin 3 (AQP3) has been demonstrated to be overexpressed in GC tissues and is thought to be involved in GC carcinogenesis and progression. However, the role of AQP3 in chemosensitivity of GC to cytotoxic agents remains unknown. In this study, we show that AQP3 overexpression induced resistance to cDDP in AGS cells (P<0.05), and AQP3 knockdown increased the chemosensitivity in MGC803 and SGC7901 cells (P<0.05). Moreover, cDDP treatment enhanced AQP3 expression in MGC803, SGC7901 and AGS cells. AQP3 overexpression promoted the conversion of LC3-I to LC3-II in AGS cells, whereas AQP3 knockdown inhibited this conversion in MGC803 and SGC7901 cells. AQP3 upregulation increased Atg5 and Beclin-1 expression, and inhibited P62 expression in AGS cells, whereas AQP3 knockdown showed the opposite results in MGC803 and SGC7901 cells. Chloroquine (CQ), an autophagy inhibitor, enhanced the cytotoxicity of cDDP in GC cells, and CQ reversed the chemoresistance to cDDP caused by AQP3 overexpression in GC cells. Together, our data demonstrate that AQP3 facilitates cisplatin resistance in gastric cancer cells via autophagy, and suggest that the development of AQP3-based tumor therapeutics could play a key role in future GC treatment strategies.

Potential role of aquaporin 3 in gastric intestinal metaplasia

Gastric intestinal metaplasia (GIM) is a pre-cancerous condition and a pivotal step in the formation of gastric cancer (GC). Aquaporin 3 (AQP3) has been found to be expressed in goblet cells rather than mucus-secreting glands. To investigate the characteristics of GIM in non-cancerous tissues adjacent to GC, as well as the expression and role of AQP3 in GIM tissues, 16 patients diagnosed with gastric adenocarcinoma of intestinal type located in the lesser curve of the antrum were consecutively enrolled in this study. A new pathological technology called "gastric mucosal sausage roll" was introduced. GIM was determined according to the updated Sydney system, and AQP3 expression in goblet cells was determined by immunohistochemistry. GIM was found in all stomach specimens, and its incidence increased with progression to GC (P < 0.001). GIM prevalence displayed remarkable association with the distance to GC in the anterior gastric wall tissues (P = 0.016) and tissues toward the cardia (P = 0.014), such that GIM was more common in the areas closer to GC (P < 0.001). AQP3 was found to be expressed in 67.71% of parts with GIM, and AQP3 immunoreactivity was identified more frequently in severe GIM areas (P < 0.001). In short, the incidence and severity of GIM correlated with the distance from GC, and AQP3 was differentially expressed in goblet cells, with most AQP3-positive goblet cells presenting in severe GIM. Together, this study suggests that AQP3 may play an important role in gastric carcinogenesis from GIM.

Expression, Distribution and Role of Aquaporin Water Channels in Human and Animal Stomach and Intestines

Stomach and intestines are involved in the secretion of gastrointestinal fluids and the absorption of nutrients and fluids, which ensure normal gut functions. Aquaporin water channels (AQPs) represent a major transcellular route for water transport in the gastrointestinal tract. Until now, at least 11 AQPs (AQP1–11) have been found to be present in the stomach, small and large intestines. These AQPs are distributed in different cell types in the stomach and intestines, including gastric epithelial cells, gastric glands cells, absorptive epithelial cells (enterocytes), goblet cells and Paneth cells. AQP1 is abundantly distributed in the endothelial cells of the gastrointestinal tract. AQP3 and AQP4 are mainly distributed in the basolateral membrane of epithelial cells in the stomach and intestines. AQP7, AQP8, AQP10 and AQP11 are distributed in the apical of enterocytes in the small and large intestines. Although AQP-null mice displayed almost no phenotypes in gastrointestinal tracts, the alterations of the expression and localization of these AQPs have been shown to be associated with the pathology of gastrointestinal disorders, which suggests that AQPs play important roles serving as potential therapeutic targets. Therefore, this review provides an overview of the expression, localization and distribution of AQPs in the stomach, small and large intestine of human and animals. Furthermore, this review emphasizes the potential roles of AQPs in the physiology and pathophysiology of stomach and intestines.

Tbx3 overexpression in human gastric cancer is correlated with advanced tumor stage and nodal status and promotes cancer cell growth and invasion

The objective of the current study was to investigate the expression pattern of Tbx3 and its clinicopathological significance in patients with gastric cancer. The expression pattern of Tbx3 in gastric cancer tissues and adjacent noncancerous surface epithelia and mucosal glands was detected by immunohistochemistry. Tbx3 was found to be overexpressed in 46 of 98 human gastric cancer samples, and this correlated with advanced clinical stage, tumor stage, and nodal status. In addition, in the SGC-7901 gastric cancer cell line, Tbx3 overexpression by plasmid transfection promoted growth and invasion. Conversely, depleting Tbx3 expression by small-interfering RNA inhibited proliferation and invasion in BGC-823 cell line. Moreover, Tbx3 accelerated cell cycle progression at the G1/S boundary. Tbx3 also regulated epithelial-to-mesenchymal transition (EMT) to promote cell invasion by repressing E-cadherin expression and increasing expression levels N-cadherin, vimentin. These results indicate that in gastric cancer, Tbx3 plays an important role and might be a useful therapy target.

Aquaporins: Their role in gastrointestinal malignancies

Aquaporins (AQPs) are small (~30 kDa monomers) integral membrane water transport proteins that allow water to flow through cell membranes in reaction to osmotic gradients in cells. In mammals, the family of AQPs has thirteen (AQP0-12) unique members that mediate critical biological functions. Since AQPs can impact cell proliferation, migration and angiogenesis, their role in various human cancers is well established. Recently, AQPs have been explored as potential diagnostic and therapeutic targets in gastrointestinal (GI) cancers. GI cancers encompass multiple sites including the colon, esophagus, stomach and pancreas. Research in the last three decades has revealed biological aspects and signaling pathways critical for the development of GI cancers. Since the majority of these cancers are very aggressive and rapidly metastasizes, identifying effective targets is crucial for treatment. Preclinical studies have utilized inhibitors of specific AQPs and knock down of AQP expression using siRNA. Although several studies have explored the role of AQPs in colorectal, esophageal, gastric, hepatocellular and pancreatic cancers, there is no comprehensive review compiling the available information on GI cancers as has been published for other malignancies such as ovarian cancer. Due to the similarities and association of various sites of GI cancers, it is helpful to consider these results collectively in order to better understand the role of specific AQPs in critical GI cancers. This review summarizes the current knowledge of the role of AQPs in GI malignancies with particular focus on diagnosis and therapeutic applications.

Role of aquaporins in cell proliferation: What else beyond water permeability?

In addition to the extensive data demonstrating the importance of mammalian AQPs for the movement of water and some small solutes across the cell membrane, there is now a growing body of evidence indicating the involvement of these proteins in numerous cellular processes seemingly unrelated, at least some of them in a direct way, to their canonical function of water permeation. Here, we have presented a broad range of evidence demonstrating that these proteins have a role in cell proliferation by various different mechanisms, namely, by allowing fast cell volume regulation during cell division; by affecting progression of cell cycle and helping maintain the balance between proliferation and apoptosis, and by crosstalk with other cell membrane proteins or transcription factors that, in turn, modulate progression of the cell cycle or regulate biosynthesis pathways of cell structural components. In the end, however, after discussing all these data that strongly support a role for AQPs in the cell proliferation process, it remains impossible to conclude that all these other functions attributed to AQPs occur completely independently of their water permeability, and there is a need for new experiments designed specifically to address this interesting issue.

Hyperglycemia Promotes Human Gastric Carcinoma Progression via Aquaporin 3

BACKGROUND

Hyperglycemia plays an important role in the development of gastric carcinoma (GC). Aquaporin 3 (AQP3) is overexpressed in GC and involved in carcinogenesis and progression of GC. Hyperglycemia promotes AQP3 expression in human peritoneal mesothelial cells.

AIMS

To investigate whether hyperglycemia promotes progression of GC via AQP3.

METHODS

We enrolled 978 patients with GC and evaluated the correlation between preoperative fasting plasma glucose and clinicopathological features. AQP3 was detected by immunohistochemistry in human GC specimens. Western blotting and real-time quantitative polymerase chain reaction evaluated changes in AQP3 expression in human GC MGC803 and SGC7901 cells after co-culture with high glucose. Transwell migration and Cell Counting Kit-8 assays were used to determine migration and proliferation of GC cells.

RESULTS

Hyperglycemia (fasting plasma glucose ≥6.1 mM) correlated with tumor size, location, and pTNM stage. AQP3 expression in tumor tissue was associated with fasting plasma glucose levels. High glucose concentration upregulated AQP3 expression in a dose- and time-dependent manner. High glucose concentration promoted GC cell migration markedly, and AQP3 knockdown with siRNA could abolish the increase in cell migration. However, high glucose concentration inhibited cell proliferation, and AQP3 knockdown significantly enhanced the inhibitory effect of high glucose. The ERK and PI3K/AKT signaling pathways were involved in high glucose regulation of AQP3 in human GC cells.

CONCLUSION

Hyperglycemia promotes GC progress via AQP3. This improves our understanding of the mechanism of hyperglycemia-induced carcinogenesis and provides a potential therapeutic strategy for GC.

microRNA and Wound Healing

microRNAs (miRNAs) are small noncoding RNA molecules which play pivotal roles in wound healing. The increased expression of certain genes and expression of some others represent a key component of the wound biology and are largely under the regulation of naturally occurring miRNAs. Understanding the dysregulated miRNAs in chronic wound biology will therefore enable the development of newer therapies. This chapter focuses on the miRNAs that can be potentially targeted for improving skin wound healing and the challenges in miRNA therapy, including considerations in miRNA target identification and delivery.

Cellular physiological approach for treatment of gastric cancer

Recent studies show that ion channels/transporters play important roles in fundamental cellular functions that would be involved in the cancer process. We review the evidence for their expression and functioning in human gastric cancer (GC), and evaluate the potential of cellular physiological approach in clinical management. Various types of ion channels, such as voltage-gated K⁺ channels, intracellular Cl^- channels and transient receptor potential channels have been found to express in GC cells and tissues, and to control cell cycles. With regard to water channels, aquaporin 3 and 5 play an important role in the progression of GC. Regulators of intracellular pH, such as anion exchanger, sodium-hydrogen exchanger, vacuolar H⁺-ATPases and carbonic anhydrases are also involved in tumorigenesis of GC. Their pharmacological manipulation and gene silencing affect cellular behaviours, suggesting their potential as therapeutic targets for GC. Our studies indicate the intracellular Cl^- concentration could act as a mediator of cellular signaling and control cell cycle progression in GC cells. Further, we demonstrate the cytocidal effects of hypotonic shock on GC cells, and indicate that the blockade of Cl^- channels/transporters enhances these effects by inhibiting regulatory volume decrease. A deeper understanding of molecular mechanisms may lead to the discovery of these cellular physiological approaches as a novel therapeutic strategy for GC.

miR-874 Inhibits cell proliferation, migration and invasion through targeting aquaporin-3 in gastric cancer

BACKGROUND

Aquaporin-3 (AQP3) is a water transporting protein which plays an oncogenic role in several malignant tumors. However, its regulatory mechanism remains elusive to date. In this study, we investigated the microRNA-mediated gene repression mechanism involved in AQP3's role.

METHODS

The potential microRNAs targeting AQP3 were searched via bioinformatic methods and identified by luciferase reporter assays, microRNA RT-PCR and western blotting. The expression patterns of miR-874 and AQP3 in human gastric cancer (GC) specimens and cell lines were determined by microRNA RT-PCR and western blotting. 5-ethynyl-2'-deoxyuridine, cell migration and invasion assays and tumorigenicity in vivo were adopted to observe the effects of miR-874 depletion or ectopic miR-874 expression on GC cell phenotypes. Cell apoptosis was evaluated by FACS and TUNEL in vitro and in vivo respectively.

RESULTS

miR-874 suppressed AQP3 expression by binding to the 3'UTR of AQP3 mRNA in GC cells. miR-874 was significantly down-regulated and reversely correlated with AQP3 protein levels in clinical samples. Analysis of the clinicopathological significance showed that miR-874 and AQP3 were closely correlated with GC characteristics. Functional analyses indicated that ectopic miR-874 expression suppressed the growth, migration, invasion and tumorigenicity of GC cells, whereas miR-874 knockdown promoted these phenotypes. Down-regulation of Bcl-2, MT1-MMP, MMP-2 and MMP-9 and upregulation of caspase-3 activity and Bax were involved in miR-874 inducing cell apoptosis, and inhibiting migration and invasion.

CONCLUSIONS

These results provide a mechanism by which AQP3 is upregulated, as well as highlight the importance of miR-874 in gastric cancer development and progression.

Aquaporin 3 promotes epithelial-mesenchymal transition in gastric cancer

Background

Gastric carcinoma (GC) is a common and lethal malignancy, and epithelial-mesenchymal transition (EMT) is believed to contribute to invasive and metastatic tumor growth. Aquaporin 3 (AQP3) is overexpressed in human GC tissues, while human epidermal growth factor (EGF) and hepatocyte growth factor, which can induce EMT, are able to up-regulate AQP3 expression, subsequently promoting GC cell migration and proliferation. The purpose of this study was to investigate the effects of AQP3 on EMT in human GC.

Methods

AQP3 and EMT-related proteins were detected by immunohistochemistry in human GC specimens and their clinical significance evaluated. AQP3 knockdown was attempted using small interfering RNAs, while EGF was used to up-regulate AQP3 expression. Western blotting, real-time quantitative polymerase chain reaction assays and immunofluorescence were used to evaluate changes in expression of AQP3 and EMT-related proteins in the SGC7901 and MGC803 human GC cell lines.

Results

AQP3 up-expression was associated with EMT-related proteins in human GC specimens, which correlated with poor prognosis for GC. AQP3 modulated GC cell proliferation, migration and invasion in vitro, and induced E-cadherin repression. AQP3 also up-regulated the expression of vimentin and fibronectin in vitro. The PI3K/AKT/SNAIL signaling pathway was likely involved in the induction of EMT by AQP3 in GC.

Conclusions

AQP3 promotes EMT in human cases of GC, allowing us to understand the mechanisms of AQP3 in GC progression, thus providing a potential strategy for its treatment.

AXL and MET crosstalk to promote gonadotropin releasing hormone (GnRH) neuronal cell migration and survival

The membrane tyrosine kinase receptors, AXL and MET, are implicated in GnRH neuron migration and/or survival. We hypothesized that the receptors with their ligands, GAS6 and HGF, respectively may cross-talk in GnRH neuronal function. In NLT GnRH neuronal cells, MET co-immunoprecipitated with AXL, although HGF or GAS6 did not transphosphorylate AXL or MET, respectively. Co-expression of a kinase dead AXL blocked HGF activation of MET and indirectly AKT and p38MAPK. Silencing of AXL decreased HGF's ability to phosphorylate MET and activate AXL's downstream effectors, p38MAPK and AKT. HGF/MET signaling modulated neuron migration dependent and independent of AXL co-expression and p38MAPK. Conversely, AXL's control of GnRH neuronal survival was dependent on HGF/MET signaling. Together, these data support that the importance of membrane tyrosine kinase receptor crosstalk to regulate neuronal cell-specific developmental functions.

ERK1/2 signalling pathway is involved in CD147-mediated gastric cancer cell line SGC7901 proliferation and invasion

This study aimed to investigate the role of CD147 in the progression of gastric cancer and the signalling pathway involved in CD147-mediated gastric cancer cell line SGC7901 proliferation and invasion. Short hairpin RNA (shRNA) expression vectors targeting CD147 were constructed to silence CD147, and the expression of CD147 was monitored by quantitative realtime reverse transcriptase polymerase chain reaction and Western blot and further confirmed by immunohistochemistry in vivo. Cell proliferation was determined by Cell Counting Kit-8 assay, the activities of matrix metalloproteinase (MMP)-2 and MMP-9 were determined by gelatin zymography, and the invasion of SGC7901 was determined by invasion assay. The phosphorylation and non-phosphorylation of the mitogen-activated protein kinases, extracellular signal-regulated kinase1/2 (ERK1/2), P38 and c-Jun NH2-terminal kinase were examined by Western blot. Additionally, the ERK1/2 inhibitor U0126 were used to confirm the signalling pathway involved in CD147-mediated SGC7901 progression. The BALB/c nude mice were used to study tumour progression in vivo. The results revealed that CD147 silencing inhibited the proliferation and invasion of SGC7901 cells, and down-regulated the activities of MMP-2 and MMP-9 and the phosphorylation of the ERK1/2 in SGC7901 cells. ERK1/2 inhibitor U0126 decreased the proliferation, and invasion of SGC7901 cells, and down-regulated the MMP-2 and MMP-9 activities. In a nude mouse model of subcutaneous xenografts, the tumour volume was significantly smaller in the SGC7901/shRNA group compared to the SGC7901 and SGC7901/snc-RNA group. Immunohistochemistry analysis showed that CD147 and p-ERK1/2 protein expressions were down-regulated in the SGC7901/shRNA2 group compared to the SGC7901 and SGC7901/snc-RNA group. These results suggest that ERK1/2 pathway involves in CD147-mediated gastric cancer growth and invasion. These findings further highlight the importance of CD147 in cancer progression, indicating that CD147 would be an attractive therapeutic target for gastric cancer.

Recombinant Erdr1 suppresses the migration and invasion ability of human gastric cancer cells, SNU-216, through the JNK pathway

Erythroid differentiation regulator 1 (Erdr1) suppressed cell motility in vitro and has anti-metastatic effect in vivo on melanoma. The current study investigated the effect of recombinant Erdr1 on the migration and invasion ability of SNU-216 cell, a gastric cancer cell line. The expression of Erdr1 is inversely correlated with IL-18 expression, which has a pro-cancer effect in gastric cancer. Treatment with rErdr1 markedly suppressed the ability of SNU-216 cells to migrate and invade, indicating that recombinant Erdr1 inhibited the motility of gastric cancer cells. E-cadherin expression levels were measured to determine the factor involved in the rErdr1-suppressed motility. E-cadherin is a representative of the cadherin family, known as cell motility enhancement adhesion molecule. Our results revealed that E-cadherin levels were increased by rErdr1 treatment, suggesting the involvement of E-cadherin in rErdr1-reduced cell migration. The cells were treated with specific MAPK inhibitors such as SP600125, SB203580 or PD98059 to identify the signaling mechanism involved with rErdr1 suppressed cell migration. The results indicated that the rErdr1 inhibited migration was primarily reversed by SP600125, a JNK inhibitor. In addition, the level of JNK phosphorylation was markedly increased by recombinant Erdr1. Taken together, these findings suggest that rErdr1 suppressed the ability of gastric cancer cells to metastasis by up regulating E-cadherin through a JNK pathway activation. Furthermore, it can be suggested that the inhibitory effect of recombinant Erdr1 on SNU-216 cell's metastatic potential was through cell motility suppression.

[Correlation of aquaporin 3 expression with the clinicopathologic characteristics of non-small cell lung cancer]

背景与目的

肺癌是严重威胁人类生存和发展的恶性疾病之一，本研究旨在探讨非小细胞肺癌（non-small cell lung cancer, NSCLC）组织中水通道蛋白-3（aquaporins 3, AQP3）的表达，探讨其与NSCLC临床病理学之间的关系。

方法

应用免疫组织化学方法检测180例NSCLC组织中AQP3表达及微血管密度（micro vascular density, MVD）。

结果

NSCLC组织中AQP3阴性表达率为13.9%（25/180），中等强度阳性表达率为37.2%（67/180），强阳性表达率为48.9%（88/180）。NSCLC组织中AQP3表达高于癌旁组织，有明显统计学差异（P < 0.01）。AQP3高表达也同时伴随着MVD计数增高（P < 0.01）。男性患者AQP3表达高于女性患者（P=0.003）。腺癌中AQP3的表达较鳞癌明显增强（P < 0.001）；有淋巴结转移的病例存在AQP3高表达（P=0.026）。NSCLC中AQP3的阳性表达率与肿瘤分化程度呈正相关，表现为AQP3的阳性表达率在高分化癌中明显高于低分化癌（P < 0.001）。

结论

AQP3在NSCLC的肿瘤血管生成和进展中起重要促进作用，AQP3可能为NSCLC治疗的新靶点。

Critical role of aquaporin-3 in epidermal growth factor-induced migration of colorectal carcinoma cells and its clinical significance

Aquaporins (AQPs) are a family of small, integral membrane proteins that have been shown to play an important role in tumor development and metastasis. Several studies have demonstrated that expression of AQP3 contributes to the enhanced migration of epithelial cells and is related to differentiation, metastasis and vascular invasion in lung and gastric cancer. Therefore, we investigated whether AQP3 could enhance human colorectal carcinoma cell migration and we examined the role of AQP3 in the prognosis of colorectal carcinoma. Our results showed that human epidermal growth factor (hEGF) increased the expression of AQP3 and, subsequently, the migration ability of human colorectal carcinoma cells HCT116 in a dose- and time-dependent manner. The enhanced migration ability of HCT116 cells was blocked by the AQP3 inhibitor, CuSO(4). Overexpression of AQP3 induced by hEGF was inhibited by a PI3K/AKT inhibitor, LY294002, but the ERK inhibitor U0126 had a minor effect on the hEGF-induced AQP3 upregulation. Immunohistochemical staining of the cancer tissues and corresponding normal tissues showed that AQP3 expression in cancer tissue was higher compared to that in normal tissue. The expression intensity of AQP3 was associated with the differentiation, lymph node and distant metastasis of colorectal carcinoma patients. Our results suggest that AQP3 overexpression could facilitate colorectal carcinoma cell migration and AQP3 may be considered a potential indicator and therapeutic target for colon tumor metastasis and prognosis.

Involvement of Aquaporin 3 in Helicobacter pylori-related gastric diseases

Background

Gastric cancer is one of the most common and lethal malignant cancers worldwide, and numerous epidemiological studies have demonstrated that Helicobacter pylori (H. pylori) infection plays a key role in the development of gastric carcinomas. Our previous studies showed that aquaporin 3 (AQP3) is overexpressed in gastric carcinoma and promotes the migration and proliferation of human gastric carcinoma cells, suggesting that AQP3 may be a potentially important determinant of gastric carcinoma. However, the role of AQP3 in H. pylori carcinogenesis is unknown.

Methods

The AQP3 protein and H. pylori were detected in human gastric tissues by immunohistochemistry and modified Giemsa staining respectively. AQP3 knockdown was obtained by small interfering (si) RNA. Western blot assays and RT-PCR were used to evaluate the change of AQP3 in the human gastric cancer AGS and SGC7901 cell lines after co-culture with H. pylori. Sprague Dawley rats were orally inoculated with H. pylori to establish a rat model colonized by H. pylori.

Results

The present study found that AQP3 expression correlated with H. pylori infection status in gastric cancer tissues and corresponding normal mucosa, and H. pylori co-culture upregulated AQP3 expression in human gastric adenocarcinoma cells in vitro via the extracellular signal-regulated kinase signaling pathway. H. pylori infection also increased AQP3 expression in gastric mucosa colonized by H. pylori in a Sprague Dawley rat model.

Conclusions

These findings provide further information to understand the mechanism of H. pylori carcinogenesis and a potential strategy for the treatment of H. pylori-associated gastric carcinoma.

Tyrosine kinase inhibitors: views of selectivity, sensitivity, and clinical performance

With the manufacture of imatinib, researchers introduced tyrosine kinase inhibitors (TKIs) into the clinical setting in 2000 to treat cancers; approximately fifteen other TKIs soon followed. Imatinib remains the most successful agent, whereas all the others have had modest effects on the cancers that they target. The current challenge is to identify the agents that need to be combined with TKIs to maximize their efficacy. One of the most promising approaches is to combine immune therapy with TKI treatment. In this review, the therapeutic potential of TKIs for treatment is discussed.