Circular RNA hsa_circ_0000523 regulates the proliferation and apoptosis of colorectal cancer cells as miRNA sponge

Among the novel class of endogenous long non-coding RNAs, circular RNA (circRNA) is known as a key regulator in the development and progression of different cancers. Its function and mechanism in the tumorigenesis of colorectal cancer, however, has not been well studied. This study thus aimed to investigate potential regulation of colorectal cancer by circRNAs and the corresponding regulatory mechanism. We demonstrated that the expression of circRNA hsa_circ_0000523 (also known as circ_006229) was down-regulated in different colorectal cancer cell lines. It was also found that interference of hsa_circ_0000523 induced proliferation and suppressed apoptosis of colorectal cancer cells, the proliferation rate of which was reduced by the overexpression of hsa_circ_0000523. In addition, we found that miR-31 could recognize hsa_circ_0000523 sequence and that it acted as a "sponge" of miR-31, indirectly regulating Wnt/β-catenin signaling pathway, which was involved in the progression of colorectal cancer. The results suggested that the expression of hsa_circ_0000523 correlated to the tumorigenesis of colorectal cancer cells. In addition, as a sponge of miR-31, the low level of hsa_circ_0000523 led to activation of Wnt/β-catenin signaling pathway, inducing the subsequent progress of colorectal cancer.

Role of mitochondrial ATP-sensitive potassium channel-mediated PKC-ε in delayed protection against myocardial ischemia/reperfusion injury in isolated hearts of sevoflurane-preconditioned rats

This study aimed to determine the role of mitochondrial adenosine triphosphate-sensitive potassium (mitoKATP) channels and protein kinase C (PKC)-ε in the delayed protective effects of sevoflurane preconditioning using Langendorff isolated heart perfusion models. Fifty-four isolated perfused rat hearts were randomly divided into 6 groups (n=9). The rats were exposed for 60 min to 2.5% sevoflurane (the second window of protection group, SWOP group) or 33% oxygen inhalation (I/R group) 24 h before coronary occlusion. The control group (CON) and the sevoflurane group (SEVO) group were exposed to 33% oxygen and 2.5% sevoflurane for 60 min, respectively, without coronary occlusion. The mitoKATP channel inhibitor 5-hydroxydecanoate (5-HD) was given 30 min before sevoflurane preconditioning (5-HD+SWOP group). Cardiac function indices, infarct sizes, serum cardiac troponin I (cTnI) concentrations, and the expression levels of phosphorylated PKC-ε (p-PKC-ε) and caspase-8 were measured. Cardiac function was unchanged, p-PKC-ε expression was upregulated, caspase-8 expression was downregulated, cTnI concentrations were decreased, and the infarcts were significantly smaller (P<0.05) in the SWOP group compared with the I/R group. Cardiac function was worse, p-PKC-ε expression was downregulated, caspase-8 expression was upregulated, cTnI concentration was increased and infarcts were larger in the 5-HD+SWOP group (P<0.05) compared with the SWOP group. The results suggest that mitoKATP channels are involved in the myocardial protective effects of sevoflurane in preconditioning against I/R injury, by regulating PKC-ε phosphorylation before ischemia, and by downregulating caspase-8 during reperfusion.