ABSTRACT
Glutamate-ammonia ligase (GLUL, also known as glutamine synthetase) is a crucial enzyme that catalyzes ammonium and glutamate into glutamine in the ATP-dependent condensation. Although GLUL plays a critical role in multiple cancers, the expression and function of GLUL in gastric cancer remain unclear. In the present study, we have found that the expression level of GLUL was significantly lower in gastric cancer tissues compared with adjacent normal tissues, and correlated with N stage and TNM stage, and low GLUL expression predicted poor survival for gastric cancer patients. Knockdown of GLUL promoted the growth, migration, invasion and metastasis of gastric cancer cells in vitro and in vivo, and vice versa, which was independent of its enzyme activity. Mechanistically, GLUL competed with β-Catenin to bind to N-Cadherin, increased the stability of N-Cadherin and decreased the stability of β-Catenin by alerting their ubiquitination. Furthermore, there were lower N-Cadherin and higher β-Catenin expression levels in gastric cancer tissues compared with adjacent normal tissues. GLUL protein expression was correlated with that of N-Cadherin, and could be the independent prognostic factor in gastric cancer. Our findings reveal that GLUL stabilizes N-Cadherin by antagonizing β-Catenin to inhibit the progress of gastric cancer.
ABSTRACT
Increasing evidences suggest the important role of calcium homeostasis in hallmarks of cancer, but its function and regulatory network in metastasis remain unclear. A comprehensive investigation of key regulators in cancer metastasis is urgently needed. Transcriptome sequencing (RNA-seq) of primary esophageal squamous cell carcinoma (ESCC) and matched metastatic tissues and a series of gain/loss-of-function experiments identified potassium channel tetramerization domain containing 4 (KCTD4) as a driver of cancer metastasis. KCTD4 expression was found upregulated in metastatic ESCC. High KCTD4 expression is associated with poor prognosis in patients with ESCC and contributes to cancer metastasis in vitro and in vivo. Mechanistically, KCTD4 binds to CLIC1 and disrupts its dimerization, thus increasing intracellular Ca2+ level to enhance NFATc1-dependent fibronectin transcription. KCTD4-induced fibronectin secretion activates fibroblasts in a paracrine manner, which in turn promotes cancer cell invasion via MMP24 signaling as positive feedback. Furthermore, a lead compound K279-0738 significantly suppresses cancer metastasis by targeting the KCTD4‒CLIC1 interaction, providing a potential therapeutic strategy. Taken together, our study not only uncovers KCTD4 as a regulator of calcium homeostasis, but also reveals KCTD4/CLIC1-Ca2+-NFATc1-fibronectin signaling as a novel mechanism of cancer metastasis. These findings validate KCTD4 as a potential prognostic biomarker and therapeutic target for ESCC.
ABSTRACT
Objective The method for detecting expression of human CDK14 gene with Real-time quantitative PCR was developed.Methods To establish a method for detecting expression of human CDK14 gene with Real-time quantitative PCR by designing and synthesis of the primers of CDK14 target gene andβ-Actin reference gene and extracting total RNA from different lung cancer cell lines.Then the specificity,detection range and repeatability of this method were evaluated.At last,the expression level of CDK14 gene in different cell lines,which were with or without siRNA interference,were carried out by using this method.Results The method for detecting expression of human CDK14 gene with Real-time quantitative PCR,which had good specificity,good repeatability (CV=7.3 ％) and wide detection range (Ct value range of CDK14 and β-Actin amplification curve were 22.47～32.96 and 15.14～ 27.55 respectively,r2 =0.9844),was developed and it was verified by electrophoresis analysis,melting curve,PCR product sequencing.And CDK14 gene expression level,which was detected by this method,increased in HCC827 D5,H1650 and number 1 siRNA segment was effective interference segment.Conclusion The method for detecting expression of human CDK14 gene with Real-time quantitauve PCR was established successfully.