Circ_001680 stimulates glioma progression with the involvement of miR-186-5p
Authors: D Liu
J Li
Z Cui
Journal: European review for medical and pharmacological sciences (2020)
Discipline: PHARMACOLOGY & TOXICOLOGY
Keywords: circ_001680; glioma; proliferation; metastasis; miR-186-5p
Affiliations: Department of Neurosurgery, Shanghai Fifth People's Hospital, Fudan University, Shanghai, China. .

Abstract:  Objective: This study aims to explore the influences of circ_001680 on glioma proliferation and metastasis, and the underlying mechanism. Patients and methods: Circ_001680 levels in 40 pairs of glioma and normal tissues were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The relationship between circ_001680 level and clinical indicators in glioma patients was analyzed. After knockdown of circ_001680 in U251 and U87 cells by transfection of sh-circ_001680, changes in proliferative, migratory and invasive abilities were assessed by cell counting kit-8 (CCK-8), transwell and wound healing assay, respectively. The binding relationship between circ_001680 and miR-186-5p was predicted by online bioinformatics tools and detected by Dual-Luciferase reporter assay. In addition, their synergistic regulations on glioma progression were explored by rescue experiments. Results: Circ_001680 was highly expressed in glioma tissues than normal ones. Incidences of lymphatic metastasis and distant metastasis were higher in glioma patients expressing higher level of circ_001680 than those with a lower level. Cell function experiments uncovered that knockdown of circ_001680 inhibited proliferative and metastatic abilities in U251 and U87 cells. MiR-186-5p was downregulated in glioma tissues and negatively correlated to that of circ_001680. Knockdown of miR-186-5p could abolish the inhibitory effects of silenced circ_001680 on glioma progression. Conclusions: Circ_001680 stimulates proliferative and metastatic abilities in glioma by negatively regulating miR-186-5p level. High level of circ_001680 is closely linked to lymphatic metastasis, distant metastasis and poor prognosis in glioma patients. 

Retracted: No

PubPeer comments:
 This paper appears to be part of a large set of papers (n=200 as of today and growing) that share a very similar layout. Subsets of these papers appear to share similar Kaplan-Meier survival plots, correlation plots, flow cytometry panels, and overlapping photos of wound-healing, transwell assays, etc. Yet, there is little to no overlap between the authors of these papers or their departments and affiliated institutions. I have been calling this set the  Comb papers, because the Kaplan-Meier plots have a comb-like appearance. For PubPeer user Hoya Camphorifolia, the survival plots look like Lego blocks. Many of these survival plots show a sudden drop of survival at 75 months. Another characteristic is the lack of percentages in their Tables I in columns promising percentages, and the spread of patients into roughly equally-sized group, no matter which parameter is chosen. The very similar layout and overlapping photos suggest these papers might have all been created by the same entity, perhaps a paper mill. Here is Figure 1C from this paper, showing the Comb- (or Lego-)like survival plot. ![file] And here is Table I with its undelivered percentages in the High Low columns. ![file] , 
 The correlation plot shown in Figure 3D of this paper looks remarkably similar to the correlation plot in Figure 3D of J H Wu et al., ERMPS (2020), DOI: 10.26355 eurrev_202006_21651 - https: pubpeer.com publications F77F15F3992DD54E50AC0892857BF3 Here is an illustration: ![file] ,