Background: Celecoxib has shown anti-tumor activities against several types of cancer. Although the majority of research focuses on its mechanism via cyclooxygenase-2 (COX-2) enzyme inhibition, we identified a distinct mechanism behind celecoxib anti-cancer abilities. Material/Methods: We treated hepatocellular carcinoma (HCC) Huh-7 cells and tumor xenograft mice models with celecoxib to test its effects on the tumor. Using gene chip method to identify the differential expressed genes after celecoxib treatment and using pathway enrichment analysis to predict the potential pathways for further study. We transfected cells with lentiviral shRNA to detect the effect of RNA binding gene partner of NOB1 (PNO1) on tumor growth in vitro and in vivo. Further we performed western blot to detect the effect of PNO1 on the protein kinase B (AKT) pathway. Results: Celecoxib inhibited HCC cell growth in vitro and in vivo, and gene chip and pathway enrichment analysis revealed that PNO1 may be the potential target of celecoxib in HCC cells. Celecoxib significantly reduced levels of PNO1 in tumor tissue. Knockdown of PNO1 remarkably suppressed tumor growth and metastasis in vitro and in vivo. Disruption of PNO1 expression significantly reduced protein kinase B (AKT)/rapamycin (mTOR) signaling, indicating that this pathway may be involved in PNO1-mediated tumorigenic activity. Conclusions: Celecoxib may exert its anti-tumor activity by inhibiting PNO1, and that AKT/mTOR signaling helps mediate the oncogenic effects of PNO1. This work offers the first evidence for a role of PNO1 as an HCC oncogene, which may open new avenues for prevention and treatment of HCC.

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RationaleDisruption of intracellular calcium (Ca2+) homeostasis is implicated in inflammatory responses. Here we investigated endoplasmic reticulum (ER) Ca2+ efflux through the Inositol 1,4,5-trisphosphate receptor (IP3R) as a potential mechanism of inflammatory pathophysiology in a ventilator-induced lung injury (VILI) mouse model.MethodsC57BL/6 mice were exposed to mechanical ventilation using high tidal volume (HTV). Mice were pretreated with the IP3R agonist carbachol, IP3R inhibitor 2-aminoethoxydiphenyl borate (2-APB) or the Ca2+ chelator BAPTA-AM. Lung tissues and bronchoalveolar lavage fluid (BALF) were collected to measure Ca2+ concentrations, inflammatory responses and mRNA/protein expression associated with ER stress, NLRP3 inflammasome activation and inflammation. Analyses were conducted in concert with cultured murine lung cell lines.ResultsLungs from mice subjected to HTV displayed upregulated IP3R expression in ER and mitochondrial-associated-membranes (MAMs), with enhanced formation of MAMs. Moreover, HTV disrupted Ca2+ homeostasis, with increased flux from the ER to the cytoplasm and mitochondria. Administration of carbachol aggravated HTV-induced lung injury and inflammation while pretreatment with 2-APB or BAPTA-AM largely prevented these effects. HTV activated the IRE1α and PERK arms of the ER stress signaling response and induced mitochondrial dysfunction-NLRP3 inflammasome activation in an IP3R-dependent manner. Similarly, disruption of IP3R/Ca2+ in MLE12 and RAW264.7 cells using carbachol lead to inflammatory responses, and stimulated ER stress and mitochondrial dysfunction.ConclusionIncrease in IP3R-mediated Ca2+ release is involved in the inflammatory pathophysiology of VILI via ER stress and mitochondrial dysfunction. Antagonizing IP3R/Ca2+ and/or maintaining Ca2+ homeostasis in lung tissue represents a prospective treatment approach for VILI.

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