Circular RNA hsa_circ_0000277 promotes tumor progression and DDP resistance in esophageal squamous cell carcinoma.

Circular RNAs (circRNAs) are well-known regulators of cancer progression and chemoresistance in various types of cancers. This study was performed to investigate the function of hsa_circ_0000277 in esophageal squamous cell carcinoma (ESCC). RNA levels were analyzed via the reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell Counting Kit-8 (CCK-8) assay was applied to determine cell proliferation and half maximal inhibitory concentration (IC50) of cisplatin (DDP). Colony formation ability was evaluated by colony formation assay. Cell cycle and apoptosis were measured using flow cytometry. RNA immunoprecipitation (RIP), pull-down assay and dual-luciferase reporter assays were performed for target interaction analysis. The protein levels were determined through western blot. Xenograft models were established for researching hsa_circ_0000277 function in vivo. Hsa_circ_0000277 expression was increased in ESCC cells and tissues, and it had important clinical significance. Downregulation of hsa_circ_0000277 repressed ESCC cell proliferation, colony formation, cell cycle, and DDP resistance. Hsa_circ_0000277 acted as a microRNA-873-5p (miR-873-5p) sponge and Sry-related high-mobility group box 4 (SOX4) was validated as a target of miR-873-5p. Moreover, hsa_circ_0000277/miR-873-5p axis and miR-873-5p/SOX4 axis regulated ESCC cell progression and DDP resistance. Hsa_circ_0000277/miR-873-5p axis activated SOX4/Wnt/β-catenin signaling pathway. Hsa_circ_0000277 facilitated tumorigenesis and DDP resistance by miR-873-5p/SOX4 axis in vivo. These findings unraveled that hsa_circ_0000277 promoted ESCC progression and DDP resistance via miR-873-5p/SOX4/Wnt/β-catenin axis, showing a specific molecular mechanism of carcinogenesis and chemoresistance in ESCC.

Cheng J ，Zhang R ，Yan M ，Li Y ... -  《BMC CANCER》

Hsa_circ_0007142 contributes to cisplatin resistance in esophageal squamous cell carcinoma via miR-494-3p/LASP1 axis.

Chemoresistance is one of the major obstacles for tumor treatment. Circular RNAs (circRNAs) have been confirmed to play vital roles in chemoresistance of cancer, including esophageal squamous cell carcinoma (ESCC). We investigated the roles and mechanisms of circ_0007142 in cisplatin (DDP) resistance of ESCC. Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to determine the levels of circ_0007142, DOCK1 mRNA, microRNA-494-3p (miR-494-3p) and LIM And SH3 Protein 1 (LASP1) mRNA. RNase R assay was conducted to analyze the characteristic of circ_0007142. Cell Counting Kit-8 (CCK-8) assay was performed to evaluate IC50 of DDP. Flow cytometry analysis, 5-ethynyl-2'-deoxyuridine (EdU) assay and transwell assay were carried out to examine cell apoptosis, proliferation and invasion, respectively. Dual-luciferase reporter assay was employed to verify the association between miR-494-3p and circ_0007142 or LASP1. Murine xenograft assay was conducted to investigate the role of circ_0007142 in DDP resistant in vivo. The protein level of LASP1 in tumors was measured by Immunohistochemistry (IHC) analysis. Circ_0007142 was upregulated in DDP-resistant ESCC tissues and cells. Circ_0007142 knockdown improved DDP sensitivity, induced cell apoptosis and hampered cell proliferation and invasion in DDP-resistant ESCC cells. Circ_0007142 functioned as the sponge for miR-494-3p and miR-494-3p inhibition reversed the impacts of circ_0007142 knockdown on DDP resistance, cell apoptosis, proliferation, and invasion. LASP1 was a target of miR-494-3p, and the effects on DDP resistance, cell apoptosis, growth, and invasion mediated by LASP1 downregulation were rescued by miR-494-3p inhibition. Moreover, circ_0007142 knockdown enhanced DDP sensitivity in vivo. Circ_0007142 improved DDP resistance of ESCC by upregulating LASP1 via sponging miR-494-3p.

Chang N ，Ge N ，Zhao Y ，Yang L ，Qin W ，Cui Y ... -  《-》

Circular RNA circ-RNF121 contributes to cisplatin (DDP) resistance of non-small-cell lung cancer cells by regulating the miR-646/SOX4 axis.

Chemo-resistance is considered a major obstacle in the clinical treatment of non-small-cell lung cancer (NSCLC). Circular RNA (circRNA) circ-RNF121 (hsa_circ_0023404) has been identified to be related to the cisplatin (DDP) resistance. However, the role and mechanism of circ-RNF121 in the DDP resistance in NSCLC are still unknown. Real-time quantitative PCR (RT-qPCR) was applied to detect the levels of circ-RNF121, microRNA-646 (miR-646) and SRY-related HMG box transcription factor 4 (SOX4). Cell viability, proliferation, apoptosis, migration, invasion and cell cycle progression were assessed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT), colony formation, flow cytometry, wound-healing, transwell and flow cytometry assays, severally. The binding relationship between miR-646 and circ-RNF121 or SOX4 was predicted by the circular RNA interactome or Target Scan Human7.2 and then verified by a dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. SOX4 protein level was measured by western blot assay. The biological role of circ-RNF121 on NSCLC tumor growth and drug resistance was examined by the xenograft tumor model in vivo. Circ-RNF121 and SOX4 were increased, and miR-646 was declined in DDP-resistant NSCLC tissues and cells. Furthermore, the circ-RNF121 deficiency could enhance DDP sensitivity by inhibiting cell proliferation, migration, invasion, cell cycle progression and promoting apoptosis in DDP-resistant NSCLC cells in vitro. Mechanically, circ-RNF121 served as a sponge of miR-646 to increase SOX4 expression. Circ-RNF121 knockdown improved the drug sensitivity of NSCLC in vivo. Circ-RNF121 silencing could reduce the DDP resistance of NSCLC cells by regulating SOX4 expression via miR-646. These findings hinted at a promising therapeutic target for NSCLC treatment.

Liu Y ，Zhai R ，Hu S ，Liu J ... -  《-》

Circular RNA hsa_circ_0000654 promotes esophageal squamous cell carcinoma progression by regulating the miR-149-5p/IL-6/STAT3 pathway.

Circular RNAs (circRNAs) are novel noncoding RNAs (ncRNAs) with covalently closed-loop structures that play an essential regulatory role in diverse malignancies, including esophageal squamous cell cancer (ESCC). Circ_0000654 expression in ESCC and its mechanism of action remains unclear. Real-time PCR (RT-PCR) was employed to detect circ_0000654 and miR-149-5p expression in ESCC tissues. Circ_0000654 and miR-149-5p expression in ESCC cells was selectively regulated. Furthermore, interleukin 6 (IL-6) and signal transducer and activator of transcription 3 (STAT3) expression in cells was detected by RT-PCR and western blot analysis, while CCK8, BrdU, flow cytometry, and transwell assays were used to monitor cell proliferation, apoptosis, migration and invasion, respectively. The dual-luciferase reporter assay and RIP assay were used to verify the targeting relationship between circ_0000654 and miR-149-5p, miR-149-5p and IL-6. The function of circ_0000654 on ESCC cell proliferation and metastasis in vivo was examined using a subcutaneous xenograft model and a tail intravenous injection model in nude mice. Circ_0000654 was significantly upregulated in ESCC tissues and cell lines, and its high expression was remarkably associated with an increased T stage and local lymph node metastasis in ESCC patients. Circ_0000654 overexpression and knockdown experiments revealed that circ_0000654 regulated ESCC cell proliferation, migration, invasion, and apoptosis in vitro. Circ_0000654 was identified as a sponge of miR-149-5p and facilitated ESCC progression by indirectly activating the IL-6/STAT3 signaling pathway. Additionally, knocking down circ_0000654 strikingly repressed ESCC growth and metastasis in vivo. In summary, circ_0000654 functions as an oncogenic circRNA in ESCC and accelerates ESCC progression via adsorbing miR-149-5p and activating the IL-6/STAT3 signaling pathway.

Xu Z ，Tie X ，Li N ，Yi Z ，Shen F ，Zhang Y ... -  《-》

Circ_PIP5K1A regulates cisplatin resistance and malignant progression in non-small cell lung cancer cells and xenograft murine model via depending on miR-493-5p/ROCK1 axis.

Chemoresistance limits the therapeutic effect of cisplatin (DDP) on non-small cell lung cancer (NSCLC). Circular RNAs (circRNAs) function as important regulators in chemoresistance. This study aimed to explore the regulation of circRNA Phosphatidylinositol-4-Phosphate 5-Kinase Type 1 Alpha (circ_PIP5K1A) in DDP resistance. The expression analysis of circ_PIP5K1A, micoRNA-493-5p (miR-493-5p) and Rho Associated Coiled-Coil Containing Protein Kinase 1 (ROCK1) was conducted through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell sensitivity was determined using 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyl tetrazolium bromide (MTT) assay. Cell proliferation and cell viability were evaluated by colony formation assay and MTT assay, respectively. Cell cycle and apoptosis detection was performed via flow cytometry. Cell motility was examined by transwell migration or invasion assay. Dual-luciferase reporter assay was applied to confirm the target binding. ROCK1 protein level was assayed via Western blot. In vivo assay was carried out using xenograft model in mice. Circ_PIP5K1A level was abnormally increased in DDP-resistant NSCLC tissues and cells. Silencing circ_PIP5K1A reduced DDP resistance, proliferation, cell cycle progression and cell motility in DDP-resistant NSCLC cells. Circ_PIP5K1A directly interacted with miR-493-5p in NSCLC cells. The function of circ_PIP5K1A was dependent on the negative regulation of miR-493-5p. MiR-493-5p directly targeted ROCK1 and circ_PIP5K1A regulated the ROCK1 level via acting as a sponge of miR-493-5p. Overexpression of miR-493-5p inhibited chemoresistance and cancer progression by downregulating ROCK1 expression in DDP-resistant NSCLC cells. Circ_PIP5K1A regulated DDP sensitivity in vivo via the miR-493-5p/ROCK1 axis. These findings suggested that circ_PIP5K1A upregulated the ROCK1 expression to promote DDP resistance and cancer progression in NSCLC by sponging miR-493-5p.

Feng N ，Guo Z ，Wu X ，Tian Y ，Li Y ，Geng Y ，Yu Y ... -  《RESPIRATORY RESEARCH》