Hsa_circ_0026344 suppresses gastric cancer progression via modulating the miR-1290/FBP2 axis.

BACKGROUND: Circular RNAs (circRNAs) are a novel type of noncoding RNAs and play important roles in tumorigenesis, including gastric cancer (GC). However, the functions of most circRNAs remain poorly understood. In our study, we mainly learn the influence of hsa_circ_0026344 (circ_0026344) in GC progression. METHODS: Circ_0026344, miR-1290 and Fructose-1,6-bisphosphatase 2 (FBP2) expression was determined by quantitative real-time polymerase chain reaction (qRT-PCR). GC cell proliferation, migration, and invasion were detected by colony formation, 5-ethynyl-2'-deoxyuridine (EdU), and transwell assays, respectively. The interaction between circ_0026344 and miR-1290 complex was evaluated by RNA pull-down assay. The interaction of miR-1290 with circ_0026344 or FBP2 was detected using dual-luciferase reporter assay. A xenograft model was established to determine the effect of circ_0026344 on GC tumor growth in vivo. RESULTS: Circ_0026344 expression was dramatically decreased in GC cells and tissues. Circ_0026344 overexpression inhibited GC cell proliferation, migration and invasion. MiR-1290 was predicted as a target of circ_0026344 and miR-1290 overexpression attenuated the anti-tumor effect of circ_0026344 on GC cells. Furthermore, we predicted FBP2 as the target of miR-1290. FBP2 knockdown reversed the effects of circ_0026344 knockdown on GC cell malignant behaviors. Functional analysis showed that circ_0026344 upregulated FBP2 expression via miR-1290. Additionally, in vivo studies demonstrated that circ_0026344 suppressed GC tumor progression. CONCLUSION: In conclusion, circ_0026344 inhibited GC cell proliferation via the miR-1290/FBP2 axis, which might provide a new therapeutic target for GC patients.

MicroRNA-187 regulates gastric cancer progression by targeting the tumor suppressor CRMP1.

Aberrant expression of microRNAs contributes to the initiation and progression of numerous human cancers. The underlying effects and molecular mechanisms of microRNA-187 (miR-187) in gastric cancer (GC) remain unclear. The present study reports that miR-187 was significantly overexpressed in GC tissues compared to that in non-tumor tissues and was associated with malignant clinical factors such as depth of invasion (P = 0.005), tumor size (P = 0.024), lymph node metastasis (P = 0.048), and TNM stage (P = 0.035). Additionally, miR-187 promoted tumor growth in vivo, and significantly increased migration, invasion, and proliferation, but inhibited apoptosis in GC cells. It was found that collapsin response mediator protein 1 (CRMP1), a tumor suppressor, was a direct downstream target of miR-187 in GC. Furthermore, CRMP1 silencing resulted in similar effects on cell proliferation, migration, and apoptosis as those of miR-187 overexpressing GC cells. Additionally, the effects of miR-187 inhibitor on cell migration and cell apoptosis were reversed by CRMP1 downregulation. In summary, miR-187 promotes tumor progression by regulating CRMP1 expression in GC and may thus be a potential prognostic marker and a therapeutic target in GC.

MicroRNA-103 promotes tumor growth and metastasis in colorectal cancer by directly targeting LATS2.

Colorectal cancer (CRC) has become the third most common cancer worldwide and leads to a high mortality rate. Although colorectal cancer has been studied widely, the underlying molecular mechanism remains unclear. Increasing evidence shows that the abnormal expression of microRNAs (miRNAs) is involved in tumorigenesis. Previous studies have reported that miRNA-103 (miR-103) is dysregulated in CRC; however, the expression, function and mechanism of miR-103 in CRC are not well known. The present study showed that miR-103 was overexpressed in the primary tumor tissues of patients with CRC and was significantly associated with a more aggressive phenotype of CRC in patients. Survival rate analysis demonstrated that CRC patients with high miR-103 expression had a poorer overall survival compared with CRC patients with low miR-103 expression. In CRC cell lines, miR-103 inhibition significantly decreased the proliferation, invasion and migration of the cells in vitro. Furthermore, miR-103 repressed large tumor suppressor kinase 2 (LATS2) expression by directly binding to the LATS2-3'-untranslated region, and an inverse correlation was identified between the expression of miR-103 and LATS2 messenger RNA in primary CRC tissues. In addition, the restoration of LATS2 led to suppressed proliferation, invasion and migration of CRC cells. In vivo, miR-103 promotes tumor growth in nude mice. In summary, miR-103 performs a critical role in the promotion of the invasive and metastatic capacities of CRC, possibly by directly targeting LATS2. This miRNA may be involved in the development and progression of CRC.

Paeoniflorin inhibits human gastric carcinoma cell proliferation through up-regulation of microRNA-124 and suppression of PI3K/Akt and STAT3 signaling.

AIM: To examine the potential anti-tumor activity of paeoniflorin in the human gastric carcinoma cell line MGC-803. METHODS: Cell viability and cytotoxic effects in MGC-803 cells were analyzed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay, respectively. Cell apoptosis of MGC-803 cells was measured using flow cytometry, DAPI staining assay and caspase-3 activity assay. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the expression of microRNA-124 (miR-124) in response to paeoniflorin. The expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), phospho-Akt (p-Akt) and phospho-signal transducer and activator of transcription 3 (p-STAT3) were also measured by quantitative RT-PCR and Western blot analysis in normal, miR-124 and anti-miR-124 over-expressing MGC-803 cells, treated with paeoniflorin. RESULTS: Paeoniflorin was found to inhibit MGC-803 cell viability in a dose-dependent manner. Paeoniflorin treatment was associated with the induction of apoptosis and caspase-3 activity in MGC-803 cells. Paeoniflorin treatment significantly increased miR-124 levels and inhibited the expression of PI3K, Akt, p-Akt and p-STAT3 in MGC-803 cells. Interestingly, the over-expression of miR-124 inhibits PI3K/Akt and phospho-STAT3 expressions in MGC-803 cells. PI3K agonist (IGF-1, 1 µg/10 µL) or over-expression of STAT3 reversed the effect of paeoniflorin on the proliferation of MGC-803 cells. Over-expression of anti-miR-124 in MGC-803 cells reversed paeoniflorin-induced up-regulation. CONCLUSION: In summary, the in vitro data suggest that paeoniflorin is a potential novel therapeutic agent against gastric carcinoma, which inhibits cell viability and induces apoptosis through the up-regulation of miR-124 and suppression of PI3K/Akt and STAT3 signaling.

Expression of delta-like 4 (Drosophila) and vascular endothelial growth factor A in colon cancer and association with tumour angiogenesis.

OBJECTIVE: Angiogenesis depends on interaction between a variety of promoting and inhibiting factors, and is known to involve vascular endothelial growth factor (VEGF) A and the Notch signaling pathway. The present study investigated the expression of Notch ligand delta-like (DLL) 4 (Drosophila), and VEGFA in colon cancer and colorectal adenoma tissue, and the association with tumour angiogenesis. METHODS: Protein level DLL4, VEGFA and CD34 molecule (CD34) expression was detected immunohistochemically in tissue sections from patients with colon cancer and colorectal adenoma. RESULTS: Out of 80 cases (35 with colon cancer, 45 with colorectal adenoma) DLL4 and VEGFA expression was closely related to tumour diameter, clinical stage, histological grade and lymph node metastasis. DLL4 expression was significantly higher in colon cancer tissue than colorectal adenoma tissue. CONCLUSION: High levels of DLL4 expression were closely related to metastasis and prognosis in patients with colon cancer. The results of the present study support the conclusion that prognosis of colon cancer is significantly correlated with angiogenesis.

miR-132 inhibits colorectal cancer invasion and metastasis via directly targeting ZEB2.

AIM: To investigate the biological role and underlying mechanism of miR-132 in colorectal cancer (CRC) progression and invasion. METHODS: Quantitative RT-PCR analysis was used to examine the expression levels of miR-132 in five CRC cell lines (SW480, SW620, HCT116, HT29 and LoVo) and a normal colonic cell line NCM460, as well as in tumor tissues with or without metastases. The Kaplan-Meier method was used to analyze the prognostic significance of miR-132 in CRC patients. The biological effects of miR-132 were assessed in CRC cell lines using the transwell assay. Quantitative RT-PCR and western blot analyses were employed to evaluate the expression of miR-132 targets. The regulation of ZEB2 by miR-132 was confirmed using the luciferase activity assay. RESULTS: miR-132 was significantly down-regulated in the CRC cell lines compared with the normal colonic cell line (P < 0.05), as well as in the CRC tissues with distant metastases compared with the tissues without metastases (10.52 ± 4.69 vs 23.11 ± 7.84) (P < 0.001). Down-regulation of miR-132 was associated with tumor size (P = 0.016), distant metastasis (P = 0.002), and TNM stage (P = 0.020) in CRC patients. Kaplan-Meier survival curve analysis indicated that patients with low expression of miR-132 tended to have worse disease-free survival than patients with high expression of miR-132 (P < 0.001). Moreover, ectopic expression of miR-132 markedly inhibited cell invasion (P < 0.05) and the epithelial-mesenchymal transition (EMT) in CRC cell lines. Further investigation revealed ZEB2, an EMT regulator, was a downstream target of miR-132. CONCLUSION: Our study indicated that miR-132 plays an important role in the invasion and metastasis of CRC.

The role of miR-18a in gastric cancer angiogenesis.

BACKGROUND/AIMS: To investigate the effect of miR-18a on angiogenesis in gastric cancer. METHODOLOGY: We generated stable cell lines overexpressing miR-18a in SGC-7901 cells. Cell proliferation was assessed by the MTT assay. The effects of miR-18a overexpression on tumor growth and angiogenesis were assessed. Because of the key role of mammalian target of rapamycin (mTOR) signaling in gastric cancer progression, we also tested whether miR-18a overexpression affected the mTOR pathway. RESULTS: Ectopic expression of miR-18a significantly diminished cell proliferation in SGC-7901 cells (p<0.01). miR-18a overexpression significantly retarded SGC-7901 xenograft growth by 71.8% in vivo, and caused a marked reduction in tumor angiogenesis assessed by CD31-stained microvessel count. Western blot analysis of the xenografts showed that miR-18a overexpression substantially reduced the phosphorylation of two mTOR substrates, S6K1 and 4E-BPl, indicative of art inactivation of the mTOR pathway. Accompanying with the mTOR inactivation, the angiogenic factors, hypoxia-inducible factor 1 alpha and vascular endothelial growth factor, were significantly downregulated. CONCLUSIONS: These data highlighted an important role for miR-18a in controlling gastric cancer growth and angiogenesis, therefore offering a possible therapeutic strategy against this malignancy.