Zhenggang Zhu

miR-126 functions as a tumour suppressor in human gastric cancer

MicroRNAs have emerged as important gene regulators and are recognised as key players in carcinogenesis. In the present study, we show that miR-126 was significantly down-regulated in gastric cancer tissues compared with matched normal tissues and was associated with clinicopathological features, including tumour size, lymph node metastasis, local invasion and tumour-node-metastasis (TNM) stage. Ectopic expression of miR-126 in SGC-7901 gastric cancer cells potently inhibited cell growth by inducing cell cycle arrest in G0/G1 phase, migration and invasion in vitro as well as tumorigenicity and metastasis in vivo. Mechanistically, we identified the adaptor protein Crk as a target of miR-126. Taken together, our results suggest that miR-126 may function as a tumour suppressor in gastric cancer, with Crk as a direct target.

miRNA-331-3p directly targets E2F1 and induces growth arrest in human gastric cancer.

Deregulation of E2F1 activity is characteristic of gastric tumorigenesis, which involves in complex molecular mechanisms. microRNA is one of the post-transcriptional regulators for gene expression. Here, we report a member of miR-331 family, miR-331-3p, which was decreased in some kinds of malignancies. However, the biological function of miR-331-3p on gastric cancer is largely unknown. In this study, we screened the expressing levels of miR-331-3p and E2F1 in gastric cancer cell lines. We transfected precursor or inhibitor of miR-331-3p into gastric cancer cells. As results, miR-331-3p is down-regulated in all gastric cancer cell lines by real-time PCR. Over-expression of miR-331-3p blocked G1/S transition on SGC-7901 and AGS cell lines. Introduction of miR-331-3p dramatically suppressed the ability of colony formation and cell growth in vitro by interfering E2F1 activity. Our data highlight an important role of miR-331-3p in cell cycle control by targeting 3-UTR of cell cycle-related molecule E2F1. We concluded that miR-331-3p is a potential tumor suppressor in gastric cancer. Restoring miR-331-3p in gastric cancer cells revealed potential application in gastric cancer therapy.

microRNA-155 is downregulated in gastric cancer cells and involved in cell metastasis.

microRNA-155 (miR-155), an important multifunctional microRNA, has been implicated in the development of multiple solid tumors, yet, its role in gastric cancer cells has not been fully elucidated. In this study, we find that miR-155 was significantly downregulated in gastric cancer cell lines compared with an immortalized gastric epithelial cell line (GES-1). Overexpression of miR-155 in SGC-7901 and MKN-45 gastric cancer cells dramatically suppressed cell migration, invasion and adhesion in vitro. Overexpression of miR-155 significantly reduced the protein levels of SMAD2 and repressed the activity of a luciferase reporter containing one of the two predicted miR-155 binding sites in SMAD2 3-UTR, indicating that SMAD2 may be a miR-155 target gene. miR-155 expression was also remarkably restored by a DNA demethylating agent (5-Aza-2-deoxycytidine) in SGC-7901 and MKN-45 gastric cancer cells. Taken together, these data suggest that miR-155 may function as a tumor suppressor to regulate gastric cancer cell metastasis by targeting SMAD2, and its downregulation in gastric cancer cells may be partly ascribed to DNA methylation.

Value of multidetector-row computed tomography in the preoperative T and N staging of gastric carcinoma: A large-scale Chinese study

To investigate the value of multidetector‐row computed tomography (MDCT) in the preoperative T and N staging of gastric carcinoma and to further investigate the clinicopathological factors affecting the diagnostic accuracy.

MicroRNA-409-3p regulates cell proliferation and apoptosis by targeting PHF10 in gastric cancer.

Emerging evidence has indicated microRNAs are involved in tumor development and progression, acting as tumor suppressors or oncogenes. Here we report that miR-409-3p was significantly downregulated in gastric cancer (GC) cell lines and tissues. Overexpression of miR-409-3p in SGC-7901 gastric cancer cells dramatically suppressed cell proliferation and induced cell apoptosis both in vitro and in vivo. Furthermore, we demonstrate that the transcriptional regulator PHF10 was a target of miR-409-3p. Taken together, these findings suggest that miR-409-3p may function as a novel tumor suppressor in GC and its anti-oncogenic activity may involve the direct targeting and inhibition of PHF10.

Down‐regulated miR‐625 suppresses invasion and metastasis of gastric cancer by targeting ILK

Accumulating evidence has shown that microRNAs are involved in multiple processes in cancer development and progression. Here, we report that expression of miR‐625 is significantly down‐regulated and negatively correlated with lymph node metastasis in gastric cancer. miR‐625 significantly inhibits invasion and metastasis of gastric cancer cells both in vitro and in vivo. Moreover, we identify that ILK is a direct target gene for miR‐625 and knockdown of ILK has a phenocopy of overexpression of miR‐625. Taken together, our findings suggest that miR‐625 plays an important role in the mechanism of tumor metastasis.

Redox-responsive micelles self-assembled from dynamic covalent block copolymers for intracellular drug delivery.

Redox-responsive micelles self-assembled from dynamic covalent block copolymers with double disulfide linkage in the backbone have been developed successfully. The amphiphilic block copolymers PEG-PLA associated with complementary H-bonding sequences can self-assemble into spherical micelles in aqueous media with sizes from 34 nm to 107 nm with different molar mass of PEG and PLA. Moreover, in vitro drug release analyses indicate that reductive environment can result in triggered drug release profiles. The glutathione (GSH) mediated intracellular drug delivery was investigated against HeLa human cervical carcinoma cell line. Flow cytometry and fluorescence microscopy measurements demonstrated that the micelles exhibited faster drug release in glutathione monoester (GSH-OEt) pretreated HeLa cells than that in the nonpretreated cells. Cytotoxicity assay of DOX-loaded micelles indicated the higher cellular proliferation inhibition against 10 mM of GSH-OEt pretreated HeLa cells than that of the nonpretreated ones. These reduction-responsive, biodegradable and biocompatibility micelles could provide a favorable platform to construct excellent drug delivery systems for cancer therapy.

Hepatocyte growth factor activates tumor stromal fibroblasts to promote tumorigenesis in gastric cancer.

Cancer-associated fibroblasts (CAFs), as the activated fibroblasts in tumor stroma, are important modifiers of tumor progression. However, the mechanisms underlying stromal fibroblast activation and their promotion of tumor growth remain largely unknown in gastric cancer. Here, we show that normal fibroblasts (NFs) from non-cancerous regions of gastric cancer exhibit the traits of CAFs when grown together with gastric cancer cells in vivo. Activation of NFs can be induced by co-culture with gastric cancer cells, while deprivation of hepatocyte growth factor (HGF) using a neutralizing antibody inhibits the activation of NFs. Moreover, we identify HGF as an important factor from CAFs that acts in a paracrine manner to promote tumorigenesis in vitro and in vivo. Taken together, these results suggest that HGF may play a pivotal role in the regulatory circuit between gastric cancer cells and stromal fibroblasts, and neutralization of HGF inhibits both activation and tumor-promoting properties of CAFs.

Proteomic identification of serum biomarkers for gastric cancer using multi-dimensional liquid chromatography and 2D differential gel electrophoresis

BACKGROUNDnEarly diagnosis and treatment of gastric cancer patients is essential for improving prognosis. However, no available serum-based test provides sufficient sensitivity or specificity for widespread use. Therefore, in this study we aimed to identify cancer biomarkers in human sera using 2-dimensional difference gel electrophoresis (2D-DIGE), and to characterize protein biomarkers with tandem mass spectrometry.nnnMETHODSnWe compared the serum proteomic profiles of 20 gastric cancer patients and 10 healthy volunteers. Serum samples were first chromatographed using an immunoaffinity high-performance liquid chromatography (HPLC) column to selectively remove albumin, immunoglobulins, transferrin, haptoglobin, and antitrypsin. Differential protein analysis was then performed using DIGE. Significantly increased and decreased protein spot features were excised, trypsin digested, and analyzed by tandem matrix-assisted laser desorption/ionization (MALDI) time of flight (TOF)/TOF and a linear trap quadrupole (LTQ) mass spectrometer.nnnRESULTSnSeventeen protein spot features were significantly increased and 7 were significantly decreased in cancer serum samples compared to healthy controls. We identified 7 unique proteins that were upregulated, including plasminogen, apolipoprotein A-IV, Kininogen-1, complex-forming glycoprotein HC, complement component C4A, apolipoprotein J, and clusterin, and 5 that were decreased.nnnCONCLUSIONSnThese results suggest that the combination of multi-dimensional HPLC and 2D-DIGE provides a valuable tool for serum proteomics in gastric cancer.

Hypermethylated FAM5C and MYLK in Serum as Diagnosis and Pre-Warning Markers for Gastric Cancer

Most cases of gastric cancer (GC) are not diagnosed at early stage which can be curable, so it is necessary to identify effective biomarkers for its diagnosis and pre-warning. We have used methylated DNA immunoprecipitation (MeDIP) to identify genes that are frequently methylated in gastric cancer cell lines. Promoter regions hypermethylation of candidate genes were tested by methylation-specific polymerase chain reaction (MSP) in serum samples, including GC (n = 58), gastric precancerous lesions (GPL, n = 46), and normal controls (NC, n = 30). Eighty two hypermethylated genes were acquired by array analysis and 5 genes (BCAS4, CHRM2, FAM5C, PRAC and MYLK) were selected as the candidate genes. Three genes (CHRM2, FAM5C and MYLK) were further confirmed to show methylation rates increased with progression from NC to GPL, then to GC. There was obvious decrease in detection of FAM5C and MYLK hypermethylation, but not CHRM2, from preoperative to postoperative evaluation (P < 0.001). Combined detection of FAM5C and MYLK hypermethylation had a higher sensitivity in GC diagnosis (77.6%,45/58) and pre-warning (30.4%,14/46) than one single gene detection and also had a high specificity of 90%. The combined hypermethylated status of FAM5C and MYLK correlated with tumor size (P < 0.001), tumor invasion depth (P = 0.001) and tumor-node-metastasis (TNM) stage (P = 0.003). Hypermethylated FAM5C and MYLK can be used as potential biomarkers for diagnosis and pre-warning of GC.