Circular RNA hsa_circ_0000654 promotes esophageal squamous cell carcinoma progression by regulating the miR-149-5p/IL-6/STAT3 pathway.

Circular RNAs (circRNAs) are novel noncoding RNAs (ncRNAs) with covalently closed-loop structures that play an essential regulatory role in diverse malignancies, including esophageal squamous cell cancer (ESCC). Circ_0000654 expression in ESCC and its mechanism of action remains unclear. Real-time PCR (RT-PCR) was employed to detect circ_0000654 and miR-149-5p expression in ESCC tissues. Circ_0000654 and miR-149-5p expression in ESCC cells was selectively regulated. Furthermore, interleukin 6 (IL-6) and signal transducer and activator of transcription 3 (STAT3) expression in cells was detected by RT-PCR and western blot analysis, while CCK8, BrdU, flow cytometry, and transwell assays were used to monitor cell proliferation, apoptosis, migration and invasion, respectively. The dual-luciferase reporter assay and RIP assay were used to verify the targeting relationship between circ_0000654 and miR-149-5p, miR-149-5p and IL-6. The function of circ_0000654 on ESCC cell proliferation and metastasis in vivo was examined using a subcutaneous xenograft model and a tail intravenous injection model in nude mice. Circ_0000654 was significantly upregulated in ESCC tissues and cell lines, and its high expression was remarkably associated with an increased T stage and local lymph node metastasis in ESCC patients. Circ_0000654 overexpression and knockdown experiments revealed that circ_0000654 regulated ESCC cell proliferation, migration, invasion, and apoptosis in vitro. Circ_0000654 was identified as a sponge of miR-149-5p and facilitated ESCC progression by indirectly activating the IL-6/STAT3 signaling pathway. Additionally, knocking down circ_0000654 strikingly repressed ESCC growth and metastasis in vivo. In summary, circ_0000654 functions as an oncogenic circRNA in ESCC and accelerates ESCC progression via adsorbing miR-149-5p and activating the IL-6/STAT3 signaling pathway.

Pyruvate Kinase M2 Knockdown Suppresses Migration, Invasion, and Epithelial-Mesenchymal Transition of Gastric Carcinoma via Hypoxia-Inducible Factor Alpha/B-Cell Lymphoma 6 Pathway.

Gastric carcinoma is a common malignant cancer. Pyruvate kinase M2 (PKM2) is highly expressed in cancers, including gastric carcinoma. However, its function and molecular mechanism in gastric carcinoma remains unclear. Here, we aimed to explore the function and the underlying mechanism of PKM2 on malignant phenotypes in gastric carcinoma. In this study, the mRNA levels and protein levels of PKM2 in gastric carcinoma cell lines and normal gastric mucosa epithelial cell lines were detected using quantitative real-time PCR and western blot, respectively. PKM2 was downregulated by siRNA transfection. HIF-1α or BCL-6 was upregulated by corresponding overexpression plasmid. Cell viability was detected using CCK-8 assay. Cell invasion and migration were determined using transwell assay. Higher expression of PKM2 was observed in human gastric carcinoma cell lines MKN-45 and SGC-7901 than in the normal gastric mucosa epithelial cell line GES-1. PKM2 knockdown suppressed cancer cell invasion and migration and inhibited the epithelial-mesenchymal transition (EMT) phenotype by inhibiting E-cadherin and promoting vimentin and N-cadherin expression. Also, we observed that PKM2 knockdown suppressed the hypoxia-inducible factor alpha (HIF-1α) and B-cell lymphoma 6 (BCL-6) signaling pathway. HIF-1α overexpression reversed the function of PKM2 silencing on cell invasion, migration, EMT, and BCL-6 expression. BCL-6 overexpression also reversed the function of PKM2 silencing on cell invasion, migration, and EMT but did not affect HIF-1α expression. Taken together, data from our study suggest that PKM2 knockdown impeded cell migration, invasion, and EMT of gastric carcinoma cells via the HIF-1α/BCL-6 pathway.

CircRNA_001569 promotes cell proliferation through absorbing miR-145 in gastric cancer.

Gastric cancer severely threatens human life, while its pathogenesis is still unclear. The present study was to explore the potential pathogenic mechanism underlying gastric cancer. Real-time PCR was performed to detect the expression of circRNA_001569 and miR-145; western blot was performed to detect the expression of NR4A2. Cell cycle and apoptosis was determined using flow cytometry, and cell viability was determined using Cell counting kit-8 (CCK-8) assay. Luciferase reporter assay was carried out to validate the relationship between miR-145 and NR4A2. Both circRNA_001569 and NR4A2 were overexpressed in tissues and cells of gastric cancer, while miR-145 was down-regulated. Overexpressed circRNA_001569 significantly increased cell viability, and decreased cell apoptosis, while down-regulated circRNA_001569 dramatically decreased cell viability and promoted cell apoptosis. CircRNA_001569 regulated the expression of miR-145, the effect of pcDNA-circRNA_001569 was abolished by miR-145 mimic and the effect of si-circRNA_001569 was abolished by miR-145 inhibitor. MiR-145 targets NR4A2 to regulate its expression. Overexpressed miR-145 suppressed cell viability and promoted cell apoptosis. Taken together, the present study indicated that overexpressed circRNA_001569 promoted cell viability of gastric cancer through suppressing the expression of miR-145, which was mediated by NR4A2. The research will provide great theoretical basis for further clinical diagnosis and therapy.