miR-145-5p affects the differentiation of gastric cancer by targeting KLF5 directly

Krüppel-like factor 5 (KLF5) takes part in the pathologic processes of many types of cancer; however, its expression and roles in the biological behavior of gastric cancer remain unknown. TargetScan suggested that miR-145-5p is the predicted effective and conserved microRNA (miRNA) that binds to KLF5 through its 3′-untranslated region (UTR). We investigated the expression of KLF5 and miR-145-5p messenger RNA (mRNA) in gastric cancer and then analyzed its role in the biological behavior of gastric cancer cells. Our results indicated that KLF5 expression was detected by immunohistochemistry in 39.7% of the gastric cancer cases and was increased compared with that of the corresponding noncancerous normal mucosa (0.01 < p < 0.05). The poorly differentiated subtype showed positive KLF5 expression, whereas the differentiated subtype showed negative KLF5 expression (p < 0.05). Dual-luciferase reporter assay suggested KLF5 3′-UTR was the direct target of miR-145-5p. Compared with the differentiated gastric cancer, miR-145-5p was downregulated in undifferentiated gastric cancer (p < 0.05). The downregulation of KLF5 expression and differentiation of MGC-803 and BGC-823 caused by siKLF5 or miR-145-5p mimic transfection. Our results indicated that miR-145-5p/KLF5 3′-UTR affected the differentiation of gastric cancer. miR-145-5p was able to promote gastric cancer differentiation by targeting KLF5 3′-UTR directly. Our data suggest a novel mechanism for cancer differentiation and a new facet to the role of miR-145-5p/KLF5 in gastric cancer.     

Retracted: Vinculin promotes gastric cancer proliferation and migration and predicts poor prognosis in patients with gastric cancer

Vinculin is a highly conserved protein involved in cell proliferation, migration, and adhesion. However, the effects of vinculin on gastric cancer (GC) remain unclear. Therefore, we aimed to explore the functional role of vinculin in GC, as well as its underlying mechanism. Expression of vinculin in patients with GC was analyzed by real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Overall survival was evaluated by the Kaplan-Meier method with the log-rank test. The relationship between vinculin and clinicopathological characteristics of patients with GC was further identified. In addition, we assessed the expression of vinculin in GC cell lines. Besides, vinculin was suppressed or overexpressed by transfection with small interfering (si-vinculin) or pcDNA-vinculin and then cell viability, cell apoptosis, and/or migration was respectively examined by the 3-(4, 5-dimethylthiazole-2-yl)-2, 5-biphenyl tetrazolium bromide assay, flow cytometer, and scratch assay, respectively. Moreover, the cell cycle- and apoptosis-related proteins were detected by Western blot analysis. The expression of vinculin was significantly increased in the GC tissues and cells compared with the nontumor tissues or cells. Vinculin protein positive staining was mainly located in the cell membrane and cytoplasm. Moreover, vinculin was significantly associated with Tumor Node Metastasis (TNM) and poor differentiation. Patients with high vinculin levels had significantly worse overall survival than those with low levels. Suppression of vinculin significantly decreased cell viability and migration and promoted cell apoptosis. However, overexpression of vinculin statistically increased cell viability but had no effects on cell apoptosis. Vinculin promotes GC proliferation and migration and predicts poor prognosis in patients with GC.     

Overexpression of CDKN2B is involved in poor gastric cancer prognosis

The objective of this investigation is to elucidate the clinical significance of cyclin-dependent kinase inhibitor 2B (CDKN2B) expression regarding gastric cancer (GC), as well as to detect the involvement of CDKN2B expression in the clinicopathological indexes and prognosis of GC. Immunohistochemical analysis was used for identification of CDKN2B expression in GC specimens. Chi-square (χ²) test was applied to detect the association of CDKN2B expression and clinicopathological parameters of GC. The involvement of CDKN2B expression in the prognosis was analyzed via univariate and multivariate analysis. It was indicated that relative to the corresponding para-carcinoma tissues, CDKN2B expression was notably upregulated in GC specimens. Moreover, the expression of CDKN2B was strongly correlated with the differentiation (r = −0.182; P = .015), invasion (r = −0.157; P = .038), distant metastases (r = −0.196; P = .004), and TNM stage (r = −0.204; P = .005). Nevertheless, no remarkable variance was related to age, tumor loci, or sex. Kaplan-Meier survival curve and univariate analysis showed that CDKN2B overexpression predicted poorer disease-free survival (P = .007) and overall survival (P = .005) in those with GC. In addition, Cox proportional hazards regression model revealed that CDKN2B was an isolated biomarker of disease-free survival and overall survival in patients with GC. Taken together, our data demonstrated that the overexpression of CDKN2B could be an isolated factor for GC prognostic in patients. CDKN2B gene may be a useful target and new treatment for improving the prognosis of GC.     

Long noncoding RNA LINC-PINT is inhibited in gastric cancer and predicts poor survival

Long noncoding RNA (lncRNA) LINC-PINT expression is inhibited in many types of cancer cells, suggesting its role as a tumor suppressor. However, the functionality of LINC-PINT in gastric cancer and the clinical values are unknown. In the present study, we found that lncRNA LINC-PINT was downregulated, while microRNA-21 (miR-21) was upregulated in tumor tissues than in adjacent healthy tissues of gastric cancer patients. A significant and inverse correlation between expression levels of lncRNA LINC-PINT and miR-21 was found in both tumor tissues and adjacent healthy tissues. The low expression level of LINC-PINT and high expression level of the miR-21 tumor were correlated with poor prognosis. LINC-PINT overexpression casued miR-21 inhibition in cells of human gastric cancer cell lines, while miR-21 overexpression did not alter LINC-PINT expression. LINC-PINT overexpression led to inhibited, while miR-21 overexpression led to promoted proliferation, migration, and invasion of gastric cancer cells. Effects of LINC-PINT overexpression on cellular behaviors of gastric cancer cells were attenuated by miR-21 overexpression. Therefore, LINC-PINT may participate in gastric cancer through the crosstalk with miR-21.     

Low expression of Beclin 1, associated with high Bcl-xL,predicts a malignant phenotype and poor prognosis of gastric cancer

Recent studies have suggested that dysregulation of autophagy plays a pivotal role in tumorigenesis. Here, we determined the prognostic value of autophagy-related protein Beclin 1 in gastric cancer. A total of 153 primary gastric cancer patients were subjected to analysis of Beclin 1 expression and survival prognosis. Among them, 68 patients were assigned randomly and used as a training set to generate a cutoff score for Beclin 1 expression by receive operating characteristic (ROC) curve analysis. The ROC-generated cutoff score was subjected to analyze the association of Beclin 1 with clinical characteristics and patient outcome. In a testing set (n = 85) and overall patients (n = 153), both univariate and multivariate analysis found that low expression of Beclin 1 predicted adverse overall survival and progression-free survival for gastric cancer patients. Furthermore, in each stage of gastric cancer patients, Beclin 1 expression was a prognostic indicator in patients with stage II, III and IV. Importantly, a reverse relationship between Beclin 1 and Bcl-xL expression was demonstrated. In patients of elevated Bcl-xL expression, a subset with lower Beclin 1 expression displayed an inferior overall survival and progression-free survival than those with higher Beclin 1 expression. Thus, our data demonstrated that low expression of Beclin 1, associated with high Bcl-xL, played as an independent biomarker, contributing to a more aggressive cancer cell phenotype and poor prognosis for gastric tumor.     

TNFAIP8 regulates gastric cancer growth via mTOR-Akt-ULK1 pathway and autophagy signals

In this study, the purpose of this study was to investigate the role of TNFAIP8 in gastric cancer (GC). The expression of TNFAIP8 was detected by RT-PCR or western blot . TNFAIP8 was silenced or overexpressed in two cell lines. CCK-8 assay, transwell assay and flow cytometry were used to analyse cell viability, cell invasion capability and apoptosis, respectively. Nude mice were inoculated with TNFAIP8 silencing or overexpressing cells to form transplanted tumours. HE staining and immunohistochemistry assay were performed to assess histopathological changes in tumours. We found that the mRNA and protein expression of TNFAIP8 were significantly up-regulated in GC tumour tissues and cells compared with the normal counterparts. Overexpression of TNFAIP8 in GC cells increased cell viability, decreased apoptosis and promoted the cell migration ability. Meanwhile, increased expression of TNFAIP8 promoted autophagy, while inhibiting mTOR-Akt-ULK1 signal pathway. In conclusions, this study presents data that TNFAIP8 inhibits GC cells presumably by down-regulating mTOR-Akt-ULK1 signal pathway and activating autophagy signal.     

PTTG3P promotes gastric tumour cell proliferation and invasion and is an indicator of poor prognosis

Pseudogenes play a crucial role in cancer progression. However, the role of pituitary tumour‐transforming 3, pseudogene (PTTG3P) in gastric cancer (GC) remains unknown. Here, we showed that PTTG3P expression was abnormally up‐regulated in GC tissues compared with that in normal tissues both in our 198 cases of clinical samples and the cohort from The Cancer Genome Atlas (TCGA) database. High PTTG3P expression was correlated with increased tumour size and enhanced tumour invasiveness and served as an independent negative prognostic predictor. Moreover, up‐regulation of PTTG3P in GC cells stimulated cell proliferation, migration and invasion both in vitro in cell experiments and in vivo in nude mouse models, and the pseudogene functioned independently of its parent genes. Overall, these results reveal that PTTG3P is a novel prognostic biomarker with independent oncogenic functions in GC.     

EphA8 acts as an oncogene and contributes to poor prognosis in gastric cancer via regulation of ADAM10

EphA8 is a member of the erythropoietin-producing hepatocellular receptor (Eph) family of receptor tyrosine kinases. Ephs and their ephrins ligands play crucial roles in many cellular processed by mediating intracellular signaling resulting from cell–cell interactions. But the underlying mechanisms of EphA8 in gastric cancer (GC) remains unclearly. 298 clinical specimens in tissues microarray, and was found to be significantly higher in GC tissues compared with nontumor tissues (p < 0.001). EphA8 expression was also strongly associated with differentiation level (p = 0.025), tumor-node-metastasis stage (p = 0.019), and poor 5 years survival (p < 0.001). A panel of GC cell lines showed reduced proliferation, invasion, and migration capacities after RNA-mediated knockdown of EphA8, concomitant with downregulation of the proliferation-related proteins (cyclin A, cyclin D1, and cyclin-dependent kinase 4) and the metastasis-related (matrix metalloproteinases MMP2, and MMP9). EphA8 knockdown also decreased expression of the protease ADAM10 (a disintegrin and metalloproteinase domain-containing protein 10) and ADAM10-related protein AKT, suggesting an interaction between EphA8 and ADAM10. In conclusion, we found that EphA8, which is highly expressed in GC tissues, stimulates proliferation, invasion, and migration of cancer cells, and is an independent risk factor for poor prognosis of GC. These dates suggest that EphA8 could be new diagnostic and/or therapeutic targets for GC.     

Overexpression of GLUT1 in colorectal cancer is independently associated with poor prognosis

Background: To investigate the expression of glucose transporter 1 (GLUT1) in colorectal cancer (CRC) and its relationship to clinicopathological variables. Methods: The expression of GLUT1 in 163 primary tumors together with the corresponding normal mucosa, and 36 liver metastases was examined using real-time PCR. Results: The mean value of GLUT1 was higher in primary tumors (50.390 ± 68.648) than in the corresponding normal mucosa (20.437 ± 28.703, p<0.0001), while there was no significant difference in GLUT1 expression between CRC and liver metastasis (50.390 ± 68.648 vs 52.277 ± 52.482, p=0.190). In CRCs, GLUT1 expression was higher in poorly differentiated than in well and moderately differentiated tumors (p=0.022), and higher in stage III + IV than in stage I + II tumors (p=0.035). The patients with high-expressed GLUT1 had a worse prognosis than those with low-expressed GLUT1 independently of gender, age, tumor site, stage and differentiation (p=0.026, RR 2.737, 95% CI 1.126-6.651) in stage I-III CRCs. In liver metastasis, GLUT1 expression was higher in larger tumors than in smaller ones (p=0.025). Conclusions: Overexpression of GLUT1 in stage I-III CRCs was independently associated with poor prognosis.     

Chaperone-mediated autophagy regulates proliferation by targeting RND3 in gastric cancer

LAMP2A is the key protein of chaperone-mediated autophagy (CMA), downregulation of LAMP2A leads to CMA blockade. CMA activation has been implicated in cancer growth, but the exact mechanisms are unclear. Elevated expression of LAMP2A was found in 8 kinds of tumors (n=747), suggesting that LAMP2A may have an important role in cancer progression. Unsurprisingly, LAMP2A knockdown in gastric cancer (GC) cells hindered proliferation, accompanied with altered expression of cell cycle-related proteins and accumulation of RND3/RhoE. Interactomic and KEGG analysis revealed that RND3 was a putative CMA substrate. Further study demonstrated that RND3 silencing could partly rescue the proliferation arrest induced by LAMP2A knockdown; RND3 was increased upon lysosome inhibition via both chemicals and LAMP2A-shRNA; Furthermore, RND3 could interact with CMA components HSPA8 and LAMP2A, and be engulfed by isolated lysosomes. Thus, constant degradation of RND3 by CMA is required to sustain rapid proliferation of GC cells. At last, the clinical significance of LAMP2A was explored in 593 gastric noncancerous lesions and 173 GC tissues, the results revealed that LAMP2A is a promising biomarker for GC early warning and prognosis of female GC patients.     

Frequent amplification of PTP1B is associated with poor survival of gastric cancer patients

The protein tyrosine phosphatase 1B (PTP1B), a non-transmembrane protein tyrosine phosphatase, has been implicated in gastric pathogenesis. Several lines of recent evidences have shown that PTP1B is highly amplified in breast and prostate cancers. The aim of this study was to investigate PTP1B amplification in gastric cancer and its association with poor prognosis of gastric cancer patients, and further determine the role of PTP1B in gastric tumorigenesis. Our data demonstrated that PTP1B was significantly up-regulated in gastric cancer tissues as compared with matched normal gastric tissues by using quantitative RT-PCR (qRT-PCR) assay. In addition, copy number analysis showed that PTP1B was amplified in 68/131 (51.9%) gastric cancer cases, whereas no amplification was found in the control subjects. Notably, PTP1B amplification was positively associated with its protein expression, and was significantly related to poor survival of gastric cancer patients. Knocking down PTP1B expression in gastric cancer cells significantly inhibited cell proliferation, colony formation, migration and invasion, and induced cell cycle arrested and apoptosis. Mechanically, PTP1B promotes gastric cancer cell proliferation, survival and invasiveness through modulating Src-related signaling pathways, such as Src/Ras/MAPK and Src/phosphatidylinositol-3-kinase (PI3K)/Akt pathways. Collectively, our data demonstrated frequent overexpression and amplification PTP1B in gastric cancer, and further determined the oncogenic role of PTP1B in gastric carcinogenesis. Importantly, PTP1B amplification predicts poor survival of gastric cancer patients.     

Circular RNA circPLOD2 regulates pericyte function by targeting the transcription factor KLF4

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MicroRNA-133 regulates the expression of GLUT4 by targeting KLF15 and is involved in metabolic control in cardiac myocytes

GLUT4 shows decreased levels in failing human adult hearts. We speculated that GLUT4 expression in cardiac muscle may be fine-tuned by microRNAs. Forced expression of miR-133 decreased GLUT4 expression and reduced insulin-mediated glucose uptake in cardiomyocytes. A computational miRNA target prediction algorithm showed that KLF15 is one of the targets of miR-133. It was confirmed that over-expression of miR-133 reduced the protein level of KLF15, which reduced the level of the downstream target GLUT4. Cardiac myocytes infected with lenti-decoy, in which the 3′UTR with tandem sequences complementary to miR-133 was linked to the luciferase reporter gene, had decreased miR-133 levels and increased levels of GLUT4. The expression levels of KLF15 and GLUT4 were decreased at the left ventricular hypertrophy and congestive heart failure stage in a rat model. The present results indicated that miR-133 regulates the expression of GLUT4 by targeting KLF15 and is involved in metabolic control in cardiomyocytes.