PRKAA1, stabilized by FTO in an m6A-YTHDF2-dependent manner, promotes cell proliferation and glycolysis of gastric cancer by regulating the redox balance.

Gastric carcinoma (GC) is the fourth most common malignancy worldwide and the second cause of death of all malignancies worldwide. AMPK catalytic subunit α1 (PRKAA1) is involved in various types of cancer and PRKAA1 knockdown significantly decreased the invasiveness of GC cells. Fat mass and obesity-associated protein (FTO)-regulation of m6A has been shown to be involved in different diseases including cancer. However, the role of PRKAA1 and m6A modification in GC remains to be elucidated. PRKAA1 was silenced or overexpressed to study the role of PRKAA1 in regulating cell viability, colony formation, and glycolysis. Levels of lactic acid, GSH, and NADP+/NADPH were measured using commercial kits. Extracellular acidification rates were determined by an extracellular flux analyzer. RNA immunoprecipitation was performed to test m6A levels and the interaction between PRKAA1-3'-UTR and YTHDF2. Quantitative RT-PCR and immunoblots were applied to measure mRNA or protein levels, respectively. PRKAA1 silencing inhibited cell growth, colony formation, and glycolysis but enhanced apoptosis, while the PRKAA1 overexpression promoted cell growth, colony formation, and glycolysis but inhibited apoptosis of GC cells. Data also indicated that PRKAA1 regulated cell growth and apoptosis by regulating the redox balance. Mechanism study demonstrated that FTO regulated PRKAA1 mRNA m6A modification and stability. Clinical samples analysis demonstrated that PRKAA1 and FTO expression were increased in GC patients and positively correlated with each other. FTO increased levels of PRKAA1 by regulating its mRNA m6A modification and stability. PRKAA1, in turn, promoted cell viability, colony formation, and glycolysis but inhibited apoptosis of GC cells by promoting the redox balance.

PRKAA1 Promotes Proliferation and Inhibits Apoptosis of Gastric Cancer Cells Through Activating JNK1 and Akt Pathways.

PRKAA1 (protein kinase AMP-activated catalytic subunit α 1) is a catalytic subunit of AMP-activated protein kinase (AMPK), which plays a key role in regulating cellular energy metabolism through phosphorylation, and genetic variations in the PRKAA1 have been found to be associated with gastric cancer risk. However, the effect and underlying molecular mechanism of PRKAA1 on gastric cancer tumorigenesis, especially the proliferation and apoptosis, are not fully understood. Our data showed that PRKAA1 is highly expressed in BGC-823 and MKN45 cells and is expressed low in SGC-7901 and MGC-803 cells in comparison with the other gastric cancer cells. PRKAA1 downregulation by shRNA or treatment of AMPK inhibitor compound C significantly inhibited proliferation as well as promoted cell cycle arrest and apoptosis of BGC-823 and MKN45 cells. Moreover, the expression of PCNA and Bcl-2 and the activity of JNK1 and Akt signaling were also reduced in BGC-823 and MKN45 cells after PRKAA1 downregulation. In vivo experiments demonstrated that tumor growth in nude mice was significantly inhibited after PRKAA1 silencing. Importantly, inactivation of JNK1 or Akt signaling pathway significantly inhibited PRKAA1 overexpression-induced increased cell proliferation and decreased cell apoptosis in MGC-803 cells. In conclusion, our findings suggest that PRKAA1 increases proliferation and restrains apoptosis of gastric cancer cells through activating JNK1 and Akt pathways.

SNHG7 accelerates cell migration and invasion through regulating miR-34a-Snail-EMT axis in gastric cancer.

Small nucleolar RNA host gene 7 (SNHG7) is a newly recognized oncogenic Long non-coding RNA (lncRNA) in most human cancers. In gastric cancer, SNHG7 has been suggested to enhance cell proliferation and suppressed apoptosis through down-regulating P15 and P16 expression, but the effect of SNHG7 on gastric cancer cell migration and invasion was still unknown. In our study, we aimed to estimate the relationship between SNHG7 expression and clinical and pathological characteristics, and explore the effect of SNHG7 on gastric cancer cell migration and invasion. In our study, the levels of SNHG7 expression in gastric cancer tissues and cell lines were severally higher than in normal adjacent tissues and gastric mucosal epithelial cells. Moreover, high SNHG7 expression was positively correlated with TNM stage, depth of invasion, lymph-node metastasis and distant metastasis in gastric cancer patients. Furthermore, the multivariate Cox proportional hazard analysis further showed high SNHG7 expression was an independent poor prognostic factor for overall survival in gastric cancer patients. The studies in vitro revealed that SNHG7 directly binds to miR-34a and negatively regulates miR-34a expression, and SNHG7 enhances gastric cancer cell migration and invasion through suppressing miR-34a-Snail-EMT axis. In conclusion, SNHG7 functions as oncogenic lncRNA in gastric cancer and may be a potential therapeutic target for gastric cancer patients.Abbreviations: lncRNA: Long non-coding RNA; SNHG7: Small nucleolar RNA host gene 7; EMT: Epithelial mesenchymal transition; TNM: Tumor-Lymph Node-Metastasis.

Involvement of NF-κB signaling pathway in the regulation of PRKAA1-mediated tumorigenesis in gastric cancer.

AMP-activated alpha 1 catalytic subunit (PRKAA1) is one of the subunits of the mammalian 5'-AMP-activated protein kinase (AMPK) playing an important role in maintaining intracellular energy metabolism and associating with the risk of gastric cancer (GC). This paper aims to uncover the influences of PRKAA1 on the tumorigenesis of GC, as well as the underlying mechanisms. We found that Helicobacter pylori (H. pylori) infection markedly increased p-NF-κBp50 and NF-κBp50 expression, along with the PRKAA1 expression, which was inhibited by NF-κBp50 knockdown. NF-κBp50 and PRKAA1 expression were lower in non-tumor gastric tissues compared with that in GC tumor tissues. Up-regulation of PRKAA1 expression was correlated with poor survival in GC patients. MKN-45 and BGC-823 cells stably knockdown of PRKAA1 were transplanted into nude mice and observed the decreased cell metastasis in the lungs. PRKAA1 knockdown in GC cells showed significant decreases in the cell invasion and migration and inhibited MMP-2 expression and NF-κB activation, whereas PRKAA1 involved in NF-κBp50 mediated GC cell invasion and migration. In conclusion, our findings suggest the involvement of NF-κBp50 in the regulation of PRKAA1 in GC tumorigenesis.

Long Noncoding RNA NEAT1 Promotes Cell Proliferation And Invasion And Suppresses Apoptosis In Hepatocellular Carcinoma By Regulating miRNA-22-3p/akt2 In Vitro And In Vivo.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most aggressive cancers that is associated with cirrhosis and other chronic liver diseases. Although remarkable progress has been made in past decades, it is still necessary to continue exploring the pathology and development of HCC. OBJECTIVE: In this study, we elucidated the effect of long noncoding RNA (lncRNA) NEAT1 on HCC development and underlying mechanisms. METHODS: Clinicopathological features of HCC patients were collected and the correlations with NEAT1 expression were assessed. To determine cell activities, CCK-8, flow cytometry, invasion assays, and TUNEL assays were performed. Real-time PCR, Western blot, and luciferase reporter assays were performed to investigate the related mechanism of HCC. RESULTS: The results revealed that NEAT1 expression was associated with tumor size and differentiation where NEAT1 was upregulated in both HCC tissues and cell lines. Overexpression of NEAT1 promoted proliferation and invasion while inhibited apoptosis in HCC cells, which was opposite to the effect of NEAT1 knockdown. Also, AKT2 was increased in HCC tissues. Downregulation of AKT2 was associated with reduced cell proliferation and invasion while increased apoptosis, while overexpression of AKT2 exerted opposite roles. In addition, the expression of miRNA-22-3p displayed an inverse association with NEAT1. miRNA-22-3p mimic and inhibitor suppressed and promoted HCC development, respectively. The luciferase assay revealed that both NEAT1 and AKT2 were direct target genes of miRNA-22-3p. Furthermore, knockdown and overexpression of NEAT1 suppressed and promoted tumor growth in the HCC mouse model, which were abolished by the miRNA-22-3p inhibitor and mimic, respectively. CONCLUSION: In conclusion, the results demonstrate that NEAT1 promotes the development of HCC, both in vitro and in vivo, through regulating miRNA-22-3p/AKT2, and provides insight into developing a new strategy for HCC treatment.

ZBTB20 promotes cell migration and invasion of gastric cancer by inhibiting IκBα to induce NF-κB activation.

Zinc finger and BTB domain containing 20 (ZBTB20), a sequence-specific transcriptional repressor, has been found to be involved in tumorigenesis. However, its role(s) in gastric cancer and the molecular mechanisms involved are poorly investigated. Here, our data demonstrated that ZBTB20 expression was markedly upregulated in gastric cancer cell lines infected with Helicobacter pylori (H. pylori) and in gastric cancer tumor samples. Loss- and gain-of-function studies showed that ZBTB20 promoted cell proliferation, invasion and migration of gastric cancer cell lines. Mechanistically, the phosphorylation of NF-κBp65 and expression and activity of MMP-2 and MMP-9 were increased, while IκBα expression was decreased by ZBTB20 in gastric cancer cells. We further revealed that IκBα overexpression significantly inhibited NF-κB signaling as well as cell migration, invasion and proliferation in gastric cancer cell lines induced by ZBTB20 overexpression. Therefore, our findings emphasize an important role for ZBTB20 in controlling gastric cancer development, which is helpful to identify potential therapeutic targets for its treatment.

Clinical significance of MYT1L gene polymorphisms in Chinese patients with gastric cancer.

BACKGROUND: Myelin transcription factor 1 (MYT1) and its homologue MYT1-like (MYT1L) are the two main members of MYT/NZF family transcription factors, which are highly related, share a high degree of identity and show similar regulatory functions in neural development. There are evidences from several cytology experiments showing that MYT1 is associated with carcinoma. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we genotyped 944 surgically resected gastric cancer patients by the SNaPshot method to explore the association of MYT1L rs17039396 polymorphism with survival of gastric cancer in a Chinese population. We found that cardia cancer patients carrying MYT1L rs17039396 GG genotype survived for a significantly shorter time than those carrying the GA genotype. This significance was enhanced in the dominant model (GG vs. GA/AA, log-rank P = 0.001), suggesting a potential protect role of the variant A allele. Multivariate Cox regression analyses showed that the AG/GG genotypes were associated with a significantly decreased risk of death from gastric cancer (adjusted hazard ratio (HR) = 0.57, 95% confidence interval (CI) = 0.40-0.81). Stratification analyses further showed that such protective effect was statistically significant in subgroups of patients with tumor size ≤5 cm (adjusted HR = 0.34, 95%CI = 0.19-0.64), well-moderate gastric cancer (adjusted HR = 0.59, 95%CI = 0.35-0.98), no lymph-node metastasis (adjusted HR = 0.49, 95%CI = 0.31-0.76), no distant metastasis (adjusted HR = 0.59, 95%CI = 0.41-0.84). CONCLUSIONS/SIGNIFICANCE: In conclusion, these data represents the first demonstration that MYT1L rs17039396 variants could indentified as a favorable prognostic indicator for gastric cancer, particularly among the cardia gastric cancer. Further validation in other larger studies with different ethnic populations and functional evaluations are needed.