Down-regulation of hsa_circ_0006470 predicts tumor invasion: A new biomarker of gastric cancer

Overexpression of hsa_circ_0006470 inhibits the malignant behavior of gastric cancer cells <em>via</em> regulation of miR-1234/TP53I11 axis

Gastric cancer (GC) is a subtype of a common malignant tumor found in the digestive system. Hsa_circ_0006470 is known to be closely associated with the development of GC. Nevertheless, the mechanism by which hsa_circ_0006470 regulates the tumorigenesis of GC has not been fully elucidated. To investigate the role of hsa_circ_0006470 in GC, its expression levels were assessed in GES-1, AGS, MKN45, and SNU5 cells by reverse transcription-quantitative PCR. Fluorescence in situ hybridization was used to evaluate the localization of hsa_circ_0006470 in AGS and MKN45 cells. In addition, cell counting kit-8 and 5-ethynyl- 2’-deoxyuridine assays were performed to evaluate the viability and proliferation of GC cells, respectively. The dual-luciferase reporter assay was used to explore the interaction among hsa_circ_0006470, microRNA (miR)- 1234, and TP53I11. The expression levels of TP53I11, Akt, p-Akt, forkhead box O1, and cyclin dependent kinase 2 in AGS cells were analyzed by Western blotting. The data indicated that hsa_circ_0006470 expression was downregulated in AGS cells. In addition, overexpression (OE) of hsa_circ_0006470 could inhibit the viability and proliferation of GC cells. Moreover, OE of hsa_circ_0006470 inhibited the migration of GC cells and induced G¹ cell cycle phase arrest. Moreover, miR-1234 was bound to hsa_circ_0006470 and TP53I11 was targeted by miR-1234. Furthermore, OE of hsa_circ_0006470 inhibited the tumorigenesis of GC via the regulation of the miR-1234/TP53I11 axis. In summary, the present study demonstrated that OE of hsa_circ_0006470 notably inhibited the tumorigenesis of GC by regulating the miR-1234/TP53I11 axis. Therefore, the present study may provide a theoretical basis for exploring novel therapeutic strategies for the treatment of GC.

Hsa_circ_0000081 promotes the function of gastric cancer through sponging hsa-miR-423-5p to influence 3-phosphoinositide-dependent kinase 1 expression

Gastric cancer (GC) is one of the most common malignancies in the world, and effective therapeutic targets need to be identified for this type of cancer. In this study, circular RNA (circRNA) microarray analysis was utilized to screen differentially expressed circRNA in GC. Using quantitative reverse transcription polymerase chain reaction (qRT-PCR), hsa_circ_0000081 (circRNA-0000081) expression was found to be up-regulated in tissues and cells and was negative correlated with patients' survival time. RNase R and Actinomycin D assays indicated that circRNA-0000081 was significantly more resistant to R enzyme and had a longer half-life than linear RNA. Moreover, the knockdown or overexpression of circRNA-000081 could influence the proliferation, migration, and invasion potential of GC. Finally, dual luciferase reporter, RNA immunoprecipitation, qRT-PCR, and western blotting assays were used to verify the targeting relationship between circRNA-000081 and miRNA-423-5p or miRNA-423-5p and 3-phosphoinositide-dependent kinase 1 (PDPK1). In conclusion, circRNA-0000081 promotes the function of GC through sponging hsa-miR-423-5p to influence PDPK1 expression, which has a promising therapeutic potential for treating patients with GC.

Circular RNA circ-PLCD1 functions as a tumor suppressor in non-small cell lung cancer by inactivation of PI3K/AKT signaling pathway

Circular RNAs (circRNAs) are emerging as crucial regulators in tumorigenesis and aggressive progression. However, their biological roles in non-small cell lung cancer (NSCLC) remain largely unknown. Here, by performing circRNA high throughput sequencing in 4 paired NSCLC and normal tissues, we found a NSCLC-associated circRNA, circ-PLCD1, which was evidently downregulated in NSCLC tissues and cell lines. Circ-PLCD1 was transcriptionally activated by tumor-inhibiting protein p53, and exogenous expression of circ-PLCD1 inhibited NSCLC cell proliferation, invasion and induced apoptosis. Mechanistically, circ-PLCD1 acted as a competitive endogenous RNA (ceRNA) to sponge miR-375 and miR-1179 and elevate PTEN, a well-known inhibitor of oncogenic PI3K/AKT signaling, thereby repressing NSCLC tumorigenesis. Importantly, we also identified this ceRNA regulatory axis of circ-PLCD1/miR-375/miR-1179/PTEN in vivo by establishing a xenograft tumor model. Clinically, NSCLC patients with low circ-PLCD1 expression had larger tumor size, later clinical stage and shorter survival time than those with high circ-PLCD1 expression. Altogether, our findings reveal the important tumor suppressive role of circ-PLCD1 in NSCLC, reactivation of this circRNA may be considered as a novel therapeutic avenue for patient with NSCLC.

Down-regulation of hsa_circ_0006470 predicts tumor invasion: A new biomarker of gastric cancer

Background

Gastric cancer (GC) is a common cancer. Circular RNAs (circRNAs) regulate the pathogenesis of GC. This study aims to explore its potential as a GC biomarker.

Methods

The expression of hsa_circ_0006470 in GC tissues and GC cell lines was measured by quantitative reverse transcription‐polymerase chain reaction. The diagnostic value of hsa_circ_0006470 was estimated by the receiver operating characteristic (ROC) curve.

Results

Compared with adjacent normal tissues, the expression of hsa_circ_0006470 in GC tissues was significantly lower. The expression levels of hsa_circ_0006470 in different TNM stages and different invasion degrees were significantly different. The area under the ROC curve was 0.783, with sensitivity and specificity 0.725 and 0.750, respectively.

Conclusions

Hsa_circ_0006470 has a high value as a diagnostic biomarker for GC.