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Aim To investigate the effect of silencing circRNA ciRS-7 on cisplatin resistance of gastric cancer cells and its related mechanism. Methods Cisplatin-resistant gastric cancer cells HGC-27/DDP were constructed, ciRS-7 was silenced and HGC-27/DDP cells were treated with cisplatin. Real-time quantitative PCR (qRT-PCR) was used to detect the expression levels of ciRS-7 and microrNA-944 (miR-944). Cell counting kit-8 (CCK-8) was used to detect cell survival rate. Clone formation assay was used to detect the number of clones. Western blot was used to detect the protein expression levels of CyclinD1, proliferating cell nuclear antigen (PCNA), B-lymphocytoma-2-associated X protein (Bax), B-lymphocytoma-2 (Bcl-2) and cleaved aspartate-specific cysteine proteinase 3 (cleaved-caspase-3). Flow cytometry was used to detect cell apoptosis rate. In situ end labeling (TUNEL) was used to detect apoptosis index. Dual luciferase assay was used to verify the targeting relationship between ciRS-7 and miR-944. Results CiRS-7 was highly expressed in cisplatin-resistant gastric cancer tissues and cells, while miR-944 was low expressed in cisplatin-resistant gastric cancer tissues and cells. The survival rate, clonal formation number, protein expression levels of CyclinD1, PCNA and Bcl-2 in cisplatin-treated HGC-27/DDP cells were significantly reduced by silencing ciRS-7, while ciRS-7 expression level, apoptosis rate, apoptosis index, Bax, cleaved-caspase-3 protein expression levels of cisplatin-treated HGC-27/DDP cells were significantly raised. CiRS-7 targetedly inhibited the expression of miR-944. Conclusions Silencing ciRS-7 can reverse cisplatin resistance of gastric cancer cells, and the mechanism may be related to the promotion of miR-944 expression by silencing ciRS-7.
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@#Objective: To investigate the expression of ciRS-7 in esophageal squamous cell carcinoma (ESCC) and its effect on the cellular proliferation, migration and invasion. Methods: The cancer tissues and paired adjacent normal tissues from 60 ESCC patients treated in the Fourth Hospital of Hebei Medical University between May, 2016 andApril, 2017 were selected for this study. The expressions of ciRS-7 were detected by qRT-PCR. After over-expressing or silencing of ciRS-7, the proliferation of ESCC cell line TE1 was measured by CCK-8 assay; and the migration and invasion were tested by wound healing assay and Transwell invasion assay，respectively. Finally, the effect was validated via animal experiment. Results: CiRS-7 was highly expressed in ESCC tissues (P<0.05), and its expression level was closely related to pathological grade and lymph node metastasis (P<0.05). Over-expression of ciRS-7 significantly increased the proliferation, migration and invasion (all P<0.05) of TE1 cells; while silencing of ciRS-7 remarkably suppressed the proliferation, migration and invasion (all P<0.05). Conclusion: CiRS-7 was up-regulated in ESCC and could enhance ESCC cell proliferation, migration and invasion, suggesting that ciRS-7 could be used as a potential target for the diagnosis and treatment of ESCC.