CircC3P1 attenuated pro-inflammatory cytokine production and cell apoptosis in acute lung injury induced by sepsis through modulating miR-21

Acute lung injury (ALI) induced by sepsis is characterized by an inflammatory process related to the up‐regulation of inflammatory cytokines and chemokines. In the present study, we explored the role of circC3P1 in sepsis‐induced ALI in vitro and in vivo. The caecal ligation and puncture (CLP)‐induced sepsis model was established through CLP surgery. Forty adult male C57BL/6 mice were randomly assigned into sham, CLP, CLP + vector and CLP + circC3P1 (each n = 10). Primary murine pulmonary microvascular endothelial cells (MPVECs) were transfected with circC3P1 or empty vector 24 hours prior to LPS treatment via Lipofectamine 2000. The expressions of circC3P1, tumour necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6) and IL‐1β were evaluated after 6‐h LPS treatment. Cell apoptosis was evaluated via flow cytometry. The CLP group demonstrated pulmonary morphological abnormalities, increased concentrations of TNF‐α, IL‐6 and IL‐1β in the lung tissue, compared with the sham group. MPVECs treated with LPS significantly elevated TNF‐α, IL‐6 and IL‐1β levels and increased cell apoptosis than that in the control group. The circC3P1 overexpression in sepsis‐induced ALI mice attenuated pulmonary injury, inflammation and apoptosis. Besides, circC3P1 revealed anti‐inflammatory and anti‐apoptotic effect in MPVEC‐treated LPS. CircC3P1 overexpression reduced cell apoptosis and pro‐inflammatory cytokines levels via down‐regulating miR‐21. CircC3P1 attenuated pro‐inflammatory cytokine production and cell apoptosis in ALI induced by sepsis through modulating miR‐21, indicating that circC3P1 is a promising therapeutic biomarker for sepsis‐induced ALI.

Circular RNA circC3P1 restrains kidney cancer cell activity by regulating miR-21/PTEN axis and inactivating PI3K/AKT and NF- kB pathways

Kidney cancer (KC) seriously impacts public health. We detected the function and mechanism of circular RNA C3P1 (circC3P1) in KC cells. CCK-8, flow cytometry, migration, and invasion assay were respectively used to investigate the efficacies of circC3P1 and microRNA (miR)-21 on cell viability, apoptosis, migration, and invasion. Phosphatase and tensin homologue deleted on chromosome 10 (PTEN), circC3P1, and miR-21 expression were changed by cell transfection and detected by quantitative reverse-transcription polymerase chain reaction. Moreover, the apoptosis/pathways-related proteins and proteins were detected by western blot analysis. Besides, the relation between PTEN and miR-21 was detected by luciferase assay. circC3P1 and PTEN were downregulated while miR-21 was upregulated in KC tissues. circC3P1 declined cell viability, migration, and invasion and caused apoptosis. Furthermore, circC3P1 negatively regulated miR-21; miR-21 mimic could reverse the efficacies of circC3P1. Besides, circC3P1 restrained the PI3K/AKT and NF-κB pathways by downregulating miR-21. Finally, PTEN was authenticated as a target of miR-21. circC3P1 restrained KC cell growth, migration, and invasion by regulating miR-21/PTEN axis and inactivating PI3K/AKT and NF-κB signaling pathways.

Circular RNA circC3P1 suppresses hepatocellular carcinoma growth and metastasis through miR-4641/PCK1 pathway

In the recent years, increasing evidences identify circular RNAs (circRNAs) as a class of important regulators in various human cancers. Nevertheless, the functions and mechanisms of most circRNAs in cancer cells remain largely unknown. In this study, we found out a significantly downregulated circRNA circC3P1 in hepatocellular carcinoma (HCC) tissues compared to adjacent normal tissues. And our results indicated that circC3P1 expression level was negatively correlated with TNM stage, tumor size and vascular invasion in HCC. Moreover, we found that circC3P1 overexpression dramatically inhibited the proliferation, migration and invasion of HCC cells in vitro and in vivo. In terms of mechanism, we found that circC3P1 could promote PCK1 expression through sponging miR-4641 in HCC cells. We showed that miR-4641 expression was negatively correlated with that of either circC3P1 or PCK1 in HCC tissues. Finally, by functional experiments, we demonstrated that knockdown of PCK1 significantly attenuated the effects of circC3P1 overexpression on HCC cell proliferation, migration and invasion. In summary, our findings illustrated that circC3P1 acts as a tumor suppressor via enhancing PCK1 expression by sponging miR-4641 in HCC.