circ_rac GTPase-Activating Protein 1 Facilitates Stemness and Metastasis of Non-Small Cell Lung Cancer via Polypyrimidine Tract-Binding Protein 1 Recruitment to Promote Sirtuin-3-Mediated Replication Timing Regulatory Factor 1 Deacetylation.

Circular RNAs have been identified as diagnostic and therapeutic targets for various tumors. The expression of circ_rac GTPase-activating protein 1 (circRACGAP1) is reported to drive the development of non-small cell lung cancer (NSCLC). This study further explored the potential mechanism of circRACGAP1-mediated development of NSCLC. The circRACGAP1 level was detected by quantitative RT-PCR. Sphere formation, CD133-positive cell percentage, and expression of octamer-binding transcription factor 4, Sox2, Nanog, and CD133 were detected to evaluate stemness of NSCLC. Migration and invasion were determined using wound healing and transwell assays. Protein expression was measured using Western blotting. The molecular mechanism was evaluated using RNA pull-down, RNA immunoprecipitation, and coimmunoprecipitation assays. In vivo tumor growth and metastasis were determined in nude mice. circRACGAP1 was highly expressed in NSCLC and was associated with stemness marker Sox2 expression. The stemness, metastasis, and epithelial mesenchymal transformation were repressed in circRACGAP1-depleted NSCLC cells. Mechanistically, circRACGAP1 recruited RNA-binding protein polypyrimidine tract-binding protein 1 to enhance the stability and expression of sirtuin-3 (SIRT3), which subsequently led to replication timing regulatory factor 1 (RIF1) deacetylation and activation of the Wnt/ß-catenin pathway. circRACGAP1 overexpression counteracted SIRT3 or RIF1 knockdown-mediated inhibition in stemness and metastasis of NSCLC cells. The in vivo tumor growth and metastasis were repressed by circRACGAP1 depletion. Patients with NSCLC with a higher serum exosomal circRACGAP1 level had a lower overall survival rate. In conclusion, circRACGAP1 facilitated stemness and metastasis of NSCLC cells through the recruitment of polypyrimidine tract-binding protein 1 to promote SIRT3-mediated RIF1 deacetylation. Our results uncover a novel regulatory mechanism of circRACGAP1 in NSCLC and identify circRACGAP1 as a promising therapeutic target.

circRACGAP1 promotes non-small cell lung cancer proliferation by regulating miR-144-5p/CDKL1 signaling pathway.

Circular RNAs (circRNAs) are involved in the regulation of many pathophysiological processes as non-coding RNAs. This study focuses on the role of circRACGAP1 in the development of non-small cell lung cancer (NSCLC). Expression patterns of circRACGAP1 and miR-144-5p in NSCLC tissues and cell lines were quantified by qRT-PCR analysis. Then, the function of circRACGAP1 on cell proliferation and tumorigenesis were confirmed in vitro and in vivo using CCK-8 assay, colony formation, EdU incorporation, and xenograft technique. The regulation of circRACGAP1 on Gefitinib resistance of NSCLC cells was evaluated by flow cytometry. The regulatory network of circRACGAP1/miR-144-5p/CDKL1 was verified by luciferase reporter assay and RNA pull-down. Western blotting analysis was performed to assess the biomarkers of cell cycle and apoptosis-associated proteins. CircRACGAP1 was highly expressed and miR-144-5p was inhibited both in NSCLC tissues and cell lines, suggesting their negative correlation in NSCLC. Knockdown of circRACGAP1 suppressed cell proliferation via arresting the cell cycle. miR-144-5p was identified as a downstream target to reverse circRACGAP1-mediated cell proliferation. miR-144-5p directly targeted the 3'-UTR of CDKL1 to regulate cell cycle of NSCLC cells. circRACGAP1 knockdown dramatically inhibited the tumor growth and enhanced the sensitivity of NSCLC to Gefitinib in vitro and in vivo. In summary, our study revealed a novel machinery of circRACGAP1/miR-144-5p/CDKL1 for the NSCLC tumorigenesis and development, providing potential diagnostic and therapeutic targets for NSCLC.

LncRNA H19 promotes epithelial mesenchymal transition and metastasis of esophageal cancer via STAT3/EZH2 axis.

BACKGROUND: Long non-coding RNA H19 (lncRNA H19) has been widely reported in esophageal cancer (EC), and previous study had found that lncRNAH19 was up-regulated in EC and promoted cell proliferation and metastasis. However, the mechanism still needs further studied. METHODS: Levels of lncRNA H19 were analyzed by qRT-PCR in matched samples from 30 patients. Expression levels of lncRNA H19, let-7, STAT3 and EZH2 were additionally identified by qRT-PCR and western blotting in five EC cell lines. The effects of lncRNA H19 on cell proliferation, migration, invasion and apoptosis in cell lines were performed by MTT assay, colony formation assay, Transwell assay and flow cytometry in vitro, and tumor formation was detected by xenograft nude mice model in vivo. The expression level of STAT3, EZH2, ß-catenin, and EMT and metastasis related molecules such as E-cadherin, N-cadherin, Snail-1 and MMP-9 was assessed by qRT-PCR and western blotting. Finally, luciferase reporter assay and RIP assay were used to verify the interaction between lncRNA H19 and let-7c, and their subsequent regulation of STAT3. RESULTS: Knockdown of lncRNA H19 repressed cell proliferation, migration and invasion as well as EMT and metastasis via STAT3-EZH2-ß-catenin pathway, while lncRNA H19 regulated STAT3 negatively regulated let-7c in EC cell lines. CONCLUSIONS: lncRNA H19 facilitates EMT and metastasis of EC through let-7c/STAT3/EZH2/ß-catenin axis.

Overexpression of DNA damage-induced 45 α gene contributes to esophageal squamous cell cancer by promoter hypomethylation.

BACKGROUND: Environmental factors-induced dysfunction of esophageal squamous epithelium, including genomic DNA impairment and apoptosis, play an important role in the pathogenesis of esophageal squamous cell cancer. DNA damage-induced 45α (GADD45α) has been found promoting DNA repair and removing methylation marker, Therefore, in this study we will investigate whether GADD45α expression is induced and its mechanism in esophageal squamous cell cancer. METHODS: Two human esophageal squamous cell lines (ESCC), ECA109 and KYSE510 were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS). Lipofectamine 2000 was used to transfect cells. mRNA level of GADD45α was measured by reverse transcription-quantitive PCR (RT-qPCR), protein level of GADD45α was detected by western blot and Immunohistochemistry. Global DNA methylation of tissue sample was measured using the Methylamp Global DNA Methylation Quantification Ultra kit (Epigentek Group) and promoter methylation was measured by bisulfite sequencing. RESULTS: GADD45a mRNA and protein levels were increased significantly in tumor tissue than that in adjacent normal tissue. Hypomethylation of global genomic DNA and GADD45α promoter were found in ESCC. The cell sensitivity to Cisplatin DDP was decreased significantly in Eca109 and Kyse510 cells, in which GADD45α expression was down-regulated by RNA interference (RNAi). In addition, silence of GADD45a expression in ESCC cells inhibited proliferation and promoted apoptosis. CONCLUSION: Overexpression of GADD45α gene is due to DNA hypomethylation in ESCC. GADD45α may be a protective factor in DDP chemotherapy for esophageal squamous cell carcinoma.

Increased connective tissue growth factor expression in a rat model of chronic heart allograft rejection.

BACKGROUND/PURPOSE: Chronic rejection limits the long-term success of cardiac transplantation and the underlying cause of the disease is unknown. Connective tissue growth factor (CTGF) is considered as a mitogenic and chemotactic factor for fibroblasts, and is associated with cell proliferation and collagen synthesis. We evaluated the expression of CTGF in a rat model of heart allograft chronic rejection. METHODS: Intra-abdominal heterotopic heart transplantation was performed from 20 Wistar rats to 20 Sprague-Dawley (SD) rats that received cyclosporine, mycophenolate mofetil and methylprednisolone as immunosuppression. Ten heart allografts were explanted at 2 and 8 weeks postoperatively for analysis of morphologic changes. The hearts from 10 normal Wistar rats served as a control group. Coronary artery density, luminal loss of myocardial coronary arteries, and myocardial fibrosis were measured. The expression of CTGF was studied by immunohistochemistry. Correlation between CTGF expression and development of cardiac allograft vasculopathy (CAV) or fibrosis was studied. RESULTS: Allografts harvested at 8 weeks postoperatively showed more coronary intimal proliferation, fibrosis and CTGF expression compared with the 2-week allografts (p < 0.05) and the controls (p < 0.01), but the coronary artery density was lower than in the control group (p < 0.05). However, the control group showed negligible CTGF expression. There were strong negative correlations between the gray value of CTGF protein expression and cardiac fibrosis and coronary intimal occlusion (r = -0.734, -0.713; p < 0.01), which demonstrated that CTGF protein expression was positively correlated with cardiac fibrosis and coronary intimal occlusion. CONCLUSION: CTGF is expressed in cardiomyocytes in CAV. Increased expression of CTGF in cardiac allografts is associated with development of CAV and fibrosis formation.

Expression of connective tissue growth factor in acute heart allograft rejection in rats.

OBJECTIVE: To detect the expression of connective tissue growth factor (CTGF) in acute heart allograft rejection in rats and to investigate the relationship between CTGF expression and cardiac allograft fibrosis. METHODS: Sixteen Wister rats served as donors and another 16 Sprague-Dawely (SD) rats served as recipients. Intra-abdominal heterotopic heart transplantation was performed. All rats received 10 mg/(kg.d) cyclosporine, 40 mg/(kg.d) CellCept, and 3 mg/(kg.d)methylprednisolone immunosuppression after the surgery. Ten allografts were harvested 2 weeks postoperation while 10 normal Wister rats served as controls. The paraffin sections of harvested heart specimens were stained with hematoxylin and eosin (HE),and van Gieson(VG) for the examination of morphological changes to observe the lumen loss of myocardial coronary arteries and myocardial fibrosis. The expression of CTGF was studied by immunnohistochemical method and was measured semi quantitatively. The correlation between the CTGF expression and allograft fibrosis was studied. RESULTS: The allografts showed a typical symbol of acute rejection with excessive granulocyte infiltration around the vessel wall and myocardial interstice. There were also intimal proliferation and obvious fibrosis in the acute group and the differences between the acute and control group were significant (P< 0.05). The expression of CTGF protein was mainly located around the vascular and myocardial lesions in the acute group while the control group showed no CTGF expression. The gray scale value of CTGF was (AR vs NH: 103.52+/-6.42 vs. 182.61+/-8.72, P< 0.05). Strong negative correlations were found between the gray scale value and fibrosis formation(r=-0.734, P< 0.01). CONCLUSION: CTGF was overexpressed in acute allograft rejection rat hearts and might be involved in the pathogenesis of transplanted heart fibrosis.