Guo-Hui Fu

MiR-142-3p functions as a tumor suppressor by targeting CD133, ABCG2, and Lgr5 in colon cancer cells

Studies have shown that the expression of CD133, leucine-rich-repeat-containing G-protein-coupled receptor 5 (Lgr5), and ATP binding cassette (ABC)G2 proteins is associated with malignancy and poor prognosis in colon cancer. However, molecular regulation mechanism of the three proteins has not been elucidated. Here, we report that microRNA-142-3p (miR-142-3p) inhibits the expression of CD133, Lgr5, and ABCG2 in colon cancer cells by binding to both the 3′-untranslated region and the coding sequences of the three genes. The miR-142-3p was markedly decreased in colon cancer specimens, in which it was negatively correlated with the expression of CD133, Lgr5, and ABCG2. Reduction of miR-142-3p corresponds to poor differentiation and bigger tumor size in colon cancers. Moreover, miR-142-3p levels were reduced in cells that formed spheres compared to cells that were cultured in regular media. Transfection of miR-142-3p mimics in colon cancer cells downregulated cyclin D1 expression, induced G1 phase cell cycle arrest, and elevated the sensitivity of the cells to 5-fluorouracil. Furthermore, OCT4 suppressed miR-142-3p, and hypomethylation of the OCT4 promoter was associated with a reduction in miR-142-3p. Finally, the miR-142-3p inhibited the growth of colon cancer cells in vivo, which was accompanied by the downregulation of CD133, Lgr5, and ABCG2 in tumor tissues. Our results elucidate a novel regulation pathway in colon cancer cells and suggest a potential therapeutic approach for colon cancer therapy.

Gastrin inhibits a novel, pathological colon cancer signaling pathway involving EGR1, AE2, and P-ERK.

Human anion exchanger 2 (AE2) is a plasma membrane protein that regulates intracellular pH and cell volume. AE2 contributes to transepithelial transport of chloride and bicarbonate in normal colon and other epithelial tissues. We now report that AE2 overexpression in colon cancer cells is correlated with expression of the nuclear proliferation marker, Ki67. Survival analysis of 24 patients with colon cancer in early stage or 33 patients with tubular adenocarcinoma demonstrated that expression of AE2 is correlated with poor prognosis. Cellular and molecular experiments indicated that AE2 expression promoted proliferation of colon cancer cells. In addition, we found that transcription factor EGR1 underlies AE2 upregulation and the AE2 sequester p16INK4a (P16) in the cytoplasm of colon cancer cells. Cytoplasmic P16 enhanced ERK phosphorylation and promoted proliferation of colon cancer cells. Gastrin inhibited proliferation of colon cancer cells by suppressing expression of EGR1 and AE2 and by blocking ERK phosphorylation. Taken together, our data describe a novel EGR1/AE2/P16/P-ERK signaling pathway in colon carcinogenesis, with implications for pathologic prognosis and for novel therapeutic approaches.

EGR1 is critical for gastrin‐dependent upregulation of anion exchanger 2 in gastric cancer cells

The essential anion exchanger (AE) involved in bicarbonate secretion is AE2/SLC4A2, a membrane protein recognized to be relevant for the regulation of the intracellular pH in several cell types. Here we report that gastrin, a major gastrointestinal hormone, upregulates the expression of AE2 mRNA and protein in a cholecystokinin B receptor dependent manner in gastric cancer cells. The upregulated species of AE2 mRNA originates from the classical upstream promoter of the AE2 gene (here referred to as AE2a1) which provides the binding site for transcription factors early growth response 1 (EGR1) and SP1. EGR1 upregulated the AE2 expression that can be competitively inhibited by SP1 in co‐transfection experiments. This competitive inhibition was avoided in cells because the SP1 expression was time‐staggered to EGR1 in response to gastrin. Overexpression or knockdown of EGR1 consistently increased or decreased the expression of AE2. Our data linked a novel signal pathway involved in gastrin‐stimulated AE2 expression.

Anti-tumour effects of small interfering RNA targeting anion exchanger 1 in experimental gastric cancer

BACKGROUND AND PURPOSE Anion exchanger 1 (AE1) is an integral membrane protein found in erythrocytes. Our previous studies have demonstrated that AE1 is expressed in human gastric cancer cells and may be involved in the carcinogenesis of cancer. In this study, we further investigated the role of AE1 in gastric carcinogenesis and the anti‐tumour effects of AE1‐targeted small interfering RNAs (siRNAs) in two experimental models of gastric cancer.

Expression of cytoplasmic p16 and anion exchanger 1 is associated with the invasion and absence of lymph metastasis in gastric carcinoma

The tumor suppressor p16 is a negative regulator of the cell cycle, commonly believed to act in the nucleus. We recently found that p16 protein is expressed in the cytoplasm of gastric cancer cells, concomitantly with anion exchanger 1 (AE1). The aim of this study was to analyze the significance of cytoplasmic p16 and its relationship to AE1 in the progression of gastric cancer. Expression of p16 and AE1 was examined by immunohistochemical analysis in 196 patients; 98 with early gastric cancer and 98 with advanced gastric cancer. The relationship between cytoplasmic p16 and clinicopathological features, and the relationship between cytoplasmic p16 and AE1, were analyzed statistically. Expression of p16 was observed in the nucleus in early stage gastric cancer, but was located mainly in the cytoplasm in advanced cancer cells. Furthermore, cytoplasmic expression of p16 was correlated with AE1 expression, and both were associated with the absence of lymph metastasis in gastric cancer. In conclusion, cytoplasmic immunoreactivity of p16 appears to be a good prognostic indicator in advanced gastric cancer. Co-localization of p16 and AE1 predicts a lack of metastasis in gastric cancer. The role of cytoplasmic p16 and AE1, and the mechanisms involved in the progression of gastric cancer, warrant further investigation.

N-stearoyltyrosine protects primary cortical neurons against Aβ(1–40)-induced injury through inhibiting endocannabinoid degradation

AIMS N-stearoyltyrosine (NsTyr) as an anandamide (AEA) analog has close relationships with AEA not only in structure but also in terms of biological actions of endocannabinoids. Since β-amyloid (Aβ)-induced primary neuronal injury involves the activation of the endocannabinoid systems (ECS), the protective effects of NsTyr against Aβ(1-40)-induced neuronal injury and the mechanism were studied systematically in this paper. MAIN METHODS Cortical neurons were incubated with Aβ(1-40) for 24 h. NsTyr was added to indicated concentrations 30 min prior to injury. KEY FINDINGS The best effects of NsTyr on Aβ(1-40)-induced primary neuronal injury occurred at 10 μM. The mechanism of NsTyr on neuroprotective effects against Aβ(1-40)-induced cellular death first involved anti-apoptosis resulting from the activation of cannabinoid receptors, then the pre-receptor regulation of AEA by the inhibition of endocannabinoid inactivation. These data demonstrated that the protective effects of NsTyr on Aβ(1-40)-induced primary neuronal injury resulted from the inhibition of fatty acid amide hydrolase (FAAH) (IC50=16.54 nM) and blocked AEA uptake mediated by anandamide membrane transporter (AMT) (IC50=11.74 nM). SIGNIFICANCE The activation of ECS by inhibiting the degradation of AEA is an effective pharmacological approach to suppress Aβ-induced neuropathic injury. Our research could result in a more realistic alternative for AD treatment.

Expression of AE1/p16 promoted degradation of AE2 in gastric cancer cells

BackgroundHuman anion exchanger 1 and 2 (AE1 and AE2) mediate the exchange of Cl−/HCO3− across the plasma membrane and regulate intracellular pH (pHi). AE1 is specifically expressed on the surface of erythrocytes, while AE2 is widely expressed in most tissues, and is particularly abundant in parietal cells. Previous studies showed that an interaction between AE1 and p16 is a key event in gastric cancer (GC) progression, but the importance of AE2 in GC is unclear.MethodsThe relationship among AE1, AE2 and p16 in GC cells was characterized by molecular and cellular experiments. AE2 expression and pHi were measured after knockdown or forced expression of AE1 or p16 in GC cells. The effect of AE2 on GC growth and the correlation of AE2 expression with differentiation and prognosis of GC were also evaluated. The effect of gastrin on AE2 expression and GC growth was investigated in cellular experiments and mouse xenograft models.Resultsp16 binds to both AE1 and AE2 simultaneously. AE1 or p16 silencing elevated AE2 expression on the plasma membrane where it plays a role in pHi regulation and GC suppression. AE2 expression was decreased in GC tissue, and these decreased levels were correlated with poor differentiation and prognosis of GC. The low AE2 protein levels are due to rapid ubiquitin-mediated degradation that was facilitated in the presence of p16. Gastrin inhibited the growth of GC cells at least partially through up-regulation of AE2 expression.ConclusionAE1/p16 expression promoted AE2 degradation in GC cells. Gastrin is a potential candidate drug for targeted therapies for AE1- and p16-positive GC.

Gastrin inhibits gastric cancer progression through activating the ERK-P65-miR23a/27a/24 axis

BackgroundTo test the hypothesis that activated extracellular signal-regulated kinase (ERK) regulates P65-miR23a/27a/24 axis in gastric cancer (GC) and the ERK-P65-miR23a/27a/24 axis plays an important role in the development of GC, and to evaluate the role of gastrin in GC progression and ERK-P65-miR23a/27a/24 axis.MethodsThe component levels of the ERK-P65-miR23a/27a/24 axis in four fresh GC tissues, 101 paraffin-embedded GC tissues and four GC cell lines were determined by Western blotting, immunohistochemistry (IHC) or qRT-PCR. The effects of gastrin on GC were first evaluated by measuring gastrin serum levels in 30 healthy and 70 GC patients and performing a correlation analysis between gastrin levels and survival time in 27 GC patients after eight years of follow-up, then evaluated on GC cell lines, GC cell xenograft models, and patient-derived xenografts (PDX) mouse models. The roles of ERK-P65-miR23a/27a/24 axis in GC progression and in the effects of gastrin on GC were examined.ResultsERK- P65-miR23a/27a/24 axis was proved to be present in GC cells. The levels of components of ERK-P65-miR23a/27a/24 axis were decreased in GC tissue samples and PGC cells. The decreased levels of components of ERK-P65-miR23a/27a/24 axis were associated with poor prognosis of GC, and ERK-P65-miR23a/27a/24 axis played a suppressive role in GC progression. Low blood gastrin was correlated with poor prognosis of the GC patients and decreased expression of p-ERK and p-P65 in GC tissues. Gastrin inhibited proliferation of poorly-differentiated GC (PGC) cells through activating the ERK-P65-miR23a/27a/24 axis. Gastrin inhibited GC growth and enhanced the suppression of GC by cisplatin in mice or PGC cell culture models through activating the ERK-P65-miR23a/27a/24 axis or its components.ConclusionsERK-P65-miR23a/27a/24 axis is down-regulated, leading to excess GC growth and poor prognosis of GC. Low gastrin promoted excess GC growth and contributed to the poor prognosis of the GC patients by down-regulating ERK-P65-miR23a/27a/24 axis. Gastrin inhibits gastric cancer growth through activating the ERK-P65-miR23a/27a/24 axis.

Overexpression of dedicator of cytokinesis 2 correlates with good prognosis in colorectal cancer associated with more prominent CD8+ lymphocytes infiltration: a colorectal cancer analysis: MIAO et al.

Recently, dedicator of cytokinesis 2 (DOCK2) has been reportedly exhibited high mutation prevalence in the Asian colorectal cancer (CRC) cohort. However, the expression pattern of DOCK2 and its clinical significance in CRC were still unknown. To characterize the role of DOCK2, a tissue microarray (TMA) containing 481 archived paraffin‐embedded CRC specimens was performed by immunohistochemistry. Among which, 54 primary CRC tissues showed high expression of DOCK2 protein, while others were negative. Moreover, DOCK2 expression was positively associated with invasion depth (P < .001) and tumor size (P = .016). Significantly, Kaplan‐Meier survival analysis revealed that patients with higher DOCK2 expression had a longer overall survival time (P = .017). Furthermore, univariate and multivariate Cox regression analysis confirmed that DOCK2 is an independent prognostic marker in CRC (P = .049,; HR, 0.519; 95% CI, 0.270 to 0.997). In addition, we observed a strong correlation between the infiltration of CD8+ T lymphocytes and DOCK2 expression (P = .0119). Our findings demonstrated that overexpressed DOCK2 might involve in recruiting CD8+ T lymphocytes and serve as a novel prognostic indicator and indicated a potential therapeutic strategy by restoring DOCK2 for CRC.

Low serum gastrin associated with ER+ breast cancer development via inactivation of CCKBR/ERK/P65 signaling

BackgroundGastrin is an important gastrointestinal hormone produced primarily by G-cells in the antrum of the stomach. It normally regulates gastric acid secretion and is implicated in a number of human disease states, but how its function affects breast cancer (BC) development is not documented. The current study investigated the suppressive effects of gastrin on BC and its underlying mechanisms.MethodsSerum levels of gastrin were measured by enzyme-linked immunosorbent assay (ELISA) and correlation between gastrin level and development of BC was analyzed by chi-square test. Inhibitory effects of gastrin on BC were investigated by CCK-8 assay and nude mice models. Expressions of CCKBR/ERK/P65 in BC patients were determined through immunohistochemistry (IHC) and Western blot. Survival analysis was performed using the log-rank test.ResultsThe results indicated that the serum level of gastrin in BC patients was lower compared with normal control. Cellular and molecular experiments indicated that reduction of gastrin is associated with inactivation of cholecystokinin B receptor (CCKBR)/ERK/P65 signaling in BC cells which is corresponding to molecular type of estrogen receptor (ER) positive BC. Furthermore, we found that low expression of gastrin/CCKBR/ERK /P65 was correlated to worse prognosis in BC patients. Gastrin or ERK/P65 activators inhibited ER+ BC through CCKBR-mediated activation of ERK/P65. Moreover, combination treatment with gastrin and tamoxifen more efficiently inhibited ER+ BC than tamoxifen alone.ConclusionsWe concluded that low serum gastrin is related to increased risk of ER+ BC development. The results also established that CCKBR/ERK/P65 signaling function is generally tumor suppressive in ER+ BC, indicating therapies should focus on restoring, not inhibiting, CCKBR/ERK/P65 pathway activity.