Gui Ren

MiR-150 promotes gastric cancer proliferation by negatively regulating the pro-apoptotic gene EGR2

Accumulating evidence suggests small non-coding RNAs (microRNAs) play important roles in human cancer progression. In the present study, we found miR-150 was overexpressed in gastric cancer cell lines and tissues. Ectopic expression of miR-150 promoted tumorigenesis and proliferation of gastric cancer cells. Luciferase reporter assay demonstrated that EGR2 was a direct target of miR-150. Collectively, our study demonstrated that overexpression of miR-150 in gastric cancer could promote proliferation and growth of cancer cells at least partially through directly targeting the tumor-suppressor EGR2, suggesting a potential strategy for the development of miRNA-based treatment of gastric cancer.

Transcriptional up-regulation of RhoE by hypoxia-inducible factor (HIF)-1 promotes epithelial to mesenchymal transition of gastric cancer cells during hypoxia

Epithelial-mesenchymal transition (EMT) is a key process that drives cancer invasion. Recently, hypoxia has been reported to induce EMT, accompanied by cytoskeleton remodeling. As RhoE is a key regulator in cytoskeleton formation, we hypothesized that RhoE may play a role in hypoxia-induced EMT. For the first time, we report that RhoE protein levels increase in gastric cancer cells under hypoxic conditions. Rigorous analysis revealed that RhoE up-regulation is at the transcriptional levels and requires hypoxia-inducible factor (HIF)-1α induction, and that HIF-1α binds a hypoxia-responsive element (HRE) on the RhoE promoter. Additionally, we discovered that hypoxia or overexpression of RhoE in normoxia up-regulates the mesenchymal marker Vimentin, down-regulates the epithelial marker E-cadherin, and significantly increases cell invasion in vitro. Silencing of HIF-1α or RhoE by specific siRNAs rescued these hypoxia-induced effects. Ectopic expression of RhoE also induced up-regulation of MMP2/MMP-9 in gastric cancer cells. This study identifies RhoE as a direct target for HIF-1 in gastric cancer cells. In addition, RhoE up-regulation represents a pivotal cellular adaptive response to hypoxia with implications in gastric cancer cell EMT and invasion. We propose that RhoE-targeted therapy might inhibit the high invasive potential of gastric cancer cells in hypoxic regions.

RhoE enhances multidrug resistance of gastric cancer cells by suppressing Bax.

We have previously reported that RhoE is overexpressed in the SGC7901/VCR cell line. However, the potential role of RhoE in the development of multidrug resistance of gastric cancer is unknown. In the present study, RhoE enhanced the resistance of SGC7901 cells to several kinds of antitumor drugs. RhoE overexpression did not alter the intracellular adriamycin accumulation of SGC7901 cells nor the expression of P-gp and MRP-1, but protected SGC7901 cells from vincristine-induced apoptosis. RhoE was found to downregulate the expression of Bax at a posttranscriptional level. Western blot revealed no effects of RhoE on the activities of the Caspase family of proteins. In brief, our study demonstrated that RhoE may promote the multidrug resistance phenotype of gastric cancer cells by decreasing the expression of Bax at posttranscriptional level, thus inhibiting vincristine-induced apoptosis.

The miR27b-CCNG1-P53-miR-508-5p axis regulates multidrug resistance of gastric cancer.

Multidrug resistance (MDR) correlates with treatment failure and poor prognosis among gastric cancer (GC) patients. In a previous study using high-throughput functional screening, we identified 11 microRNAs (miRNAs) that regulate MDR in GC and found that miR-508-5p reversed MDR by targeting ABCB1 and ZNRD1. However, the mechanism by which miR-508-5p was decreased in chemo-resistant GC cells was unclear. In this study, we found that ectopic miR-27b is sufficient to sensitize tumors to chemotherapy in vitro and in vivo. Moreover, miR-27b directly targets the 3′ untranslated regions (3′-UTRs) of CCNG1, a well-known negative regulator of P53 stability. Interestingly, miR-27b up-regulation leads to increased miR-508-5p expression, and this phenomenon is mediated by CCNG1 and P53. Further investigation indicated that miR-508-5p is directly regulated by P53. Thus, the miR-27b/CCNG1/P53/miR-508-5p axis plays important roles in GC-associated MDR. In addition, miR-27b and miR-508-5p expression was detected in GC tissues with different chemo-sensitivities, and we found that tissues in which miR-27b and miR-508-5p are up-regulated are more sensitive to chemotherapy. Together, these data suggest that the combination of miR-27b and miR-508-5p represents a potential marker of MDR. Restoring the miR-27b and miR-508-5p levels might contribute to MDR reversion in future clinical practice.

Coronin 3 promotes gastric cancer metastasis via the up-regulation of MMP-9 and cathepsin K

BackgroundCoronins are a family of highly evolutionary conserved proteins reportedly involved in the regulation of actin cytoskeletal dynamics, although only coronin 3 has been shown to be related to cancer cell migration. In glioblastoma cells, the knockdown of coronin 3 inhibits cell proliferation and invasion. Coronin 3 is also associated with the aggression and metastasis of hepatocellular carcinoma. In this paper, we analyze the migration, invasion and metastasis abilities of gastric cancer cells after up- or down-regulation of coronin 3, and explore the mechanism of coronin 3 in the process of gastric cancer metastasis.ResultsThe expression of coronin 3 was higher in the highly metastatic sub-cell line MKN28-M, which we established in our laboratory. We also demonstrated that the expression of coronin 3 was remarkably higher in lymph lode metastases than in primary gastric cancer tissues, and over-expression of coronin 3 was correlated with the increased clinical stage and lymph lode metastasis. Recombinant lentiviral vectors encoding shRNAs were designed to down-regulate coronin 3 expression in gastric cancer cell lines. Stable knockdown of coronin 3 by this lentiviral vector could efficiently inhibit the migration and invasion of MKN45 gastric cancer cells. In contrast, up-regulation of coronin 3 significantly enhanced migration and invasion of MKN28-NM cells. In addition, knockdown of coronin 3 significantly reduced liver metastasis in mice after tail vein injection of gastric cancer cells. The Human Tumor Metastasis PCR Array was used to screen the metastasis-associated genes identified by the down-regulation of coronin 3, and the results suggested that, following the knockdown of coronin 3, the tumor cell migration and invasion were inhibited by the reduced expression of MMP-9 and cathepsin K.ConclusionCoronin 3 is highly expressed in gastric cancer metastases and can promote the metastatic behaviors of gastric cancer cells, including their migration and invasion.

CacyBP/SIP protein promotes proliferation and G1/S transition of human pancreatic cancer cells.

Calcyclin‐binding protein or Siah‐1‐interacting protein (CacyBP/SIP), a component of the ubiquitin‐mediated proteolysis, could participate in beta‐catenin degradation, which was found to be related to the malignant phenotypes of pancreatic cancer previously. However, the role of CacyBP/SIP itself in pancreatic cancer has not been investigated. In the present study, CacyBP/SIP expression was assayed and manipulated to reveal the potential mechanism in pancreatic cancer carcinogenesis. Here, we show that CacyBP/SIP is over‐expressed in pancreatic cancer cells. Down‐regulation of CacyBP/SIP by small interference RNA (siRNA) severely suppresses the proliferation and tumorigenesis in pancreatic cancer. G1/S transition arrest induced by inhibition of CacyBP/SIP is at least partly mediated by down‐regulation of Cyclin E and CDK2 as well as up‐regulation of p27 and Rb. Collectively, CacyBP/SIP as an enhancer of pancreatic cancer malignance might develop into another possible therapeutic target. Mol. Carcinog.

Identification of TRAK1 (Trafficking protein, kinesin-binding 1) as MGb2-Ag : A novel cancer biomarker

The present study aimed to describe the characterization of an antibody MGb2 that reacts with an epitope on gastric cancer cells, and identification of MGb2 antigen (MGb2-Ag). Immunostaining revealed its distribution in human tissues and demonstrated that the positive rate of MGb2-Ag was 81.48% in gastric cancer, 100% in gastric signet-ring cell carcinoma and mucinous adenocarcinoma, 13.16% in precancerous conditions, and 0% in chronic superficial gastritis. Using Western blotting, immunoprecipitation and MALDI-TOF MS (matrix assisted laser desorption/ionization time-of-flight mass spectrometry), MGb2-Ag was identified as TRAK1 (Trafficking protein, kinesin-binding 1), a new molecular gained limited recognition. Both MGb2 and commercial anti-TRAK1 Ab recognized prokaryotic expressed TRAK1. Immunostaining characteristics of TRAK1 were identical with MGb2-Ag in continuous sections of paraffin-embedded tissues of gastric tissues. This is the first report that TRAK1/MGb2-Ag is a promising diagnostic marker for gastric cancer and may help to detect signet-ring cell carcinoma and mucinous adenocarcinoma.

Identification and distribution of thioredoxin-like 2 as the antigen for the monoclonal antibody MC3 specific to colorectal cancer

MC3 is a colorectal cancer (CRC)‐specific mAb previously prepared in our laboratory that can detect CRC with high sensitivity and specificity. However, the target antigen for MC3 had not been identified due to technological limitations. In the present study, immunocytochemistry and immunohistochemistry revealed the expression patterns of MC3 antigen (MC3‐Ag) in colon cancer cell lines and CRC tissues. Western blotting analysis showed that the MC3 antibody reproducibly recognized two ∼30 kDa proteins in the total cell lysates of human colon carcinoma cell lines SW480 and HT‐29. Using a proteomic approach, we identified two MC3 immunoreactive spots as two isoforms of thioredoxin‐like 2 (Txl‐2) protein. Further paired immunostaining showed that Txl‐2 had the same expression profile as probed by the MC3 antibody. Western blotting also showed that both antibodies could detect the same two bands, further verifying that Txl‐2 is the antigen of MC3 antibody. Additionally, tissue arrays revealed the expression patterns of Txl‐2 in various normal and cancer tissues. Further analysis showed that Txl‐2 mRNA was elevated in 18 cases of CRC tissues compared to paracancerous tissues and adjacent normal tissues.

Systematic immunohistochemical analysis of the expression of CD46, CD55, and CD59 in colon cancer.

CONTEXT The expression of membrane-bound complement regulatory proteins (mCRPs) that inhibit the complement system in normal tissues is essential for self-protection against an autologous immune reaction. However, the expression patterns of mCRPs, including CD46, CD55, and CD59, are inconsistent in different types of cancer cells. OBJECTIVES To determine whether CD46, CD55, and CD59 are differentially expressed in neoplastic and adjacent normal colon tissues and to assess their clinical significance. DESIGN Immunohistochemistry was performed on tissue microarrays of cancerous and adjacent normal colon tissues. RESULTS The expression levels of CD46, CD55, and CD59 were significantly higher in colon cancer tissues compared with the normal adjacent colon tissues. We found that the expression levels of CD55 and CD59 correlated with the grade of differentiation in colon cancers. In addition, the expression of CD55 and CD59 was greater in stage III and stage IV colon cancers than in stage I and stage II cancers according to staging by the TNM classification. CONCLUSIONS CD46, CD55, and CD59 are up-regulated in colon cancer. Specifically, CD55 and CD59 are of clinical relevance to differentiation and TNM staging of colon cancer. These data suggest that CD46, CD55, and CD59 have the potential to be used for molecular staging diagnoses and for colon cancer therapies.

Comparison of Endoscopic and Open Resection for Small Gastric Gastrointestinal Stromal Tumor.

The National Comprehensive Cancer Network recommends conservative follow-up for gastric gastrointestinal stromal tumors (GISTs) less than 2 cm. We have previously reported that the mitotic index of 22.22% of small gastric GISTs exceeded 5 per 50 high-power fields and recommended that all small gastric GISTs should be resected once diagnosed. The aim of the present study is to compare the safety and outcomes of endoscopic and open resection of small gastric GISTs. From May 2010 to March 2014, a total of 90 small gastric GIST patients were enrolled in the present study, including 40 patients who underwent surgical resection and 50 patients who underwent endoscopic resection. The clinicopathological characteristics, resection-related factors, and clinical outcomes were recorded and analyzed. The clinicopathological characteristics were comparable between the two groups except for tumor location and DOG-1 expression. Compared with the surgical resection group, the operation time was shorter (P = .000), blood loss was less (P = .000), pain intensity was lower (P < .05), duration of first flatus and defecation was shorter (P < .05), and medical cost of hospitalization was lower (P = .027) in the endoscopic resection group. The complications and postoperative hospital stay were comparable between the two groups. No in situ recurrence or liver metastasis was observed during follow-up. Endoscopic resection of small gastric GISTs is safe and feasible compared with surgical resection, although perforation could not be totally avoided during and after resection. The clinical outcome of endoscopic resection is also favorable.