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Long noncoding RNAs (lncRNAs) can compete with endogenous RNAs to modulate the gene expression and contribute to oncogenesis and tumor metastasis. lncRNA NKX2‐1‐AS1 (NKX2‐1 antisense RNA 1) plays a pivotal role in cancer progression and metastasis; however, the contribution of aberrant expression of NKX2‐1‐AS1 and the mechanism by which it functions as a competing endogenous RNA (ceRNA) in gastric cancer (GC) remains elusive. NKX2‐1‐AS1 expression was detected in paired tumor and nontumor tissues of 178 GC patients by quantitative reverse transcription PCR (qRT‐PCR). Using loss‐of‐function and gain‐of‐function experiments, the biological functions of NKX2‐1‐AS1 were evaluated both in vitro and in vivo. Further, to assess that NKX2‐1‐AS1 regulates angiogenic processes, tube formation and co‐culture assays were performed. RNA binding protein immunoprecipitation (RIP) assay, a dual‐luciferase reporter assay, quantitative PCR, Western blot, and fluorescence in situ hybridization (FISH) assays were performed to determine the potential molecular mechanism underlying this ceRNA. The results indicated that NKX2‐1‐AS1 expression was upregulated in GC cell lines and tumor tissues. Overexpression of NKX2‐1‐AS1 was significantly associated with tumor progression and enhanced angiogenesis. Functionally, NKX2‐1‐AS1 overexpression promoted GC cell proliferation, metastasis, invasion, and angiogenesis, while NKX2‐1‐AS1 knockdown restored these effects, both in vitro and in vivo. RIP and dual‐luciferase assays revealed that the microRNA miR‐145‐5p is a direct target of NKX2‐1‐AS1 and that NKX2‐1‐AS1 serves as a ceRNA to sponge miRNA and regulate angiogenesis in GC. Moreover, serpin family E member 1 (SERPINE1) is an explicit target for miR‐145‐5p; besides, the NKX2‐1‐AS1/miR‐145‐5p axis induces the translation of SERPINE1, thus activating the VEGFR‐2 signaling pathway to promote tumor progression and angiogenesis. NKX2‐1‐AS1 overexpression is associated with enhanced tumor cell proliferation, angiogenesis, and poor prognosis in GC. Collectively, NKX2‐1‐AS1 functions as a ceRNA to miR‐145‐5p and promotes tumor progression and angiogenesis by activating the VEGFR‐2 signaling pathway via SERPINE1., This study revealed that NKX2‐1‐AS1 might serve as an independent prognostic biomarker in gastric cancer (GC). NKX2‐1‐AS1 promotes cell proliferation and tumor angiogenesis in GC. Moreover, NKX2‐1‐AS1 directly targets miR‐145‐5p to upregulate SERPINE1 and promote tumor progression and angiogenesis in a VEGFR‐2‐dependent manner.

Background: Recent evidence indicated that the lncRNA NKX2-1-AS1 (NKX2-1 antisense RNA 1) plays an important role in cancer progression and metastasis. However, the associated molecular mechanisms of NKX2-1-AS1 in GC are still unclear. Methods: To determine the target of the study by bioinformatic analysis. NKX2-1-AS1 expression was measured in paired tumor and non-tumor tissues of 178 GC patients, by quantitative reverse transcription PCR. The in vitro and in vivo biological functions of NKX2-1-AS1 were examined by loss-of-function and gain-of-function experiments. The potential mechanisms of this competing endogenous RNA (ceRNA) were elucidated using dual-luciferase reporter assay, quantitative PCR, Western blot, and fluorescence in situ hybridization (FISH). Results: NKX2-1-AS1 expression was upregulated in GC cell lines and tumor tissues, which was correlated with tumor progression and enhanced angiogenesis. Functionally, NKX2-1-AS1 overexpression promoted GC cell proliferation, metastasis, invasion, and angiogenesis, while NKX2-1-AS1 downregulation reversed these effects, both in vitro and in vivo. Bioinformatics analysis and dual-luciferase assay showed that the microRNA miR-145-5p is a direct target of NKX2-1-AS1, and that NKX2-1-AS1 acts as a ceRNA that regulates angiogenesis in the context of GC. The mechanistic study revealed that miR-145-5p specifically targets serpin family E member 1 (SERPINE1), and that the complex NKX2-1-AS1/miR-145-5p activates VEGFR2 signaling, via SERPINE1, to promote tumor proliferation and angiogenesis. Conclusion: NKX2-1-AS1 upregulation is associated with tumor cell proliferation, increased angiogenesis, and poor prognosis in GC patients. NKX2-1-AS1 regulates SERPINE1 expression and VEGFR2 signaling by acting as a ceRNA for miR-145-5p.

Traditionally, continuous model is usually applied to analyze the velocity error of INS-aided GNSS receiver. However, the actual implemented system is discrete. In consequence, the analysis results based on continuous model are iffy. Aimed at this problem, this paper establishes a discrete model of INS-aided third-order carrier loop according to the actual system. Then, the velocity error caused by discretization is investigated and the error mechanism is analyzed. Analysis and simulation results show that the delay of aiding information is the main error source of INS aided GNSS receiver in high dynamic scene. To improve the dynamic performance of INS-aided carrier loop efficiently, the delay of aiding information should be shortened as much as possible.