Mechanism of LncRNA FOXC2-AC1 promoting lung cancer metastasis by regulating miR-107
Authors: J-T Lu
W Chen
N Wang
J-C Meng
X-F Wu
Y-H Zhou
Journal: European review for medical and pharmacological sciences (2019)
Discipline: PHARMACOLOGY & TOXICOLOGY
Keywords: lncRNA; FOXC2-AC1; lung cancer; metastasis; miR-107
Affiliations: Department of Pulmonary and Critical Care Medicine, Taihe Hospital, Hubei University of Medicine, Shiyan, China. .

Abstract:  Objective: Previous studies have shown that long non-coding RNA (lncRNA) FOXC2-AC1 is one of cancer-promoting genes. However, the role of FOXC2-AC1 in lung cancer (LCa) has not been reported. This study aimed to investigate the expression characteristics of FOXC2-AC1 in LCa, and to further explore the mechanism by which it accelerates the metastasis of LCa. Patients and methods: Quantitative Real-time polymerase chain reaction (qRT-PCR) was used to detect the level of FOXC2-AC1 in 62 pairs of LCa tissues and adjacent normal tissues, and the relationship between FOXC2-AC1 and LCa pathological parameters as well as the prognosis of patients were analyzed. Meanwhile, FOXC2-AC1 level was further verified in LCa cells by qRT-PCR. In addition, FOXC2-AC1 knockdown and overexpression models were constructed using lentivirus in LCa cell lines including H1299 and SPCA1, and the effect of FOXC2-AC1 on the biological function of LCa cells was analyzed by cell counting kit-8 (CCK-8) test along with transwell invasion and migration assay. Finally, the potential mechanism was explored using Western blotting assay. Results: In this study, qRT-PCR results indicated that the expression level of FOXC2-AC1 in LCa was considerably higher than that in normal tissues, with statistically significant differences. Compared with patients with low expression of FOXC2-AC1, patients with high expression of FOXC2-AC1 had higher incidence of distant metastasis and lower overall survival rate. Compared with the control group, the cell proliferation, invasion and metastasis capacities of FOXC2-AC1 overexpressing group were considerably enhanced, while opposite results were observed in the FOXC2-AC1 silencing group. In addition, miR-107 expression was found significantly reduced no matter in LCa cell lines or in tissues and showed a negative correlation with FOXC2-AC1. Subsequently, luciferase reporter gene assay demonstrated that overexpression of miR-107 significantly attenuated the luciferase activity of the wild-type FOXC2-AC1 vector without reducing the activity of the mutant vector or empty vector, further proving that FOXC2-AC1 could be targeted by miR-107 through this binding site. In addition, rescue experiment also found that FOXC2-AC1 and miR-107 have mutual regulation, which jointly affected the malignant progression of LCa. Conclusions: These studies indicate that LncRNA FOXC2-AC1 is notably upregulated in LCa and is significantly correlated with LCa distant metastasis as well as poor prognosis. Therefore, it is suggested that lncRNA FOXC2-AC1 may promote malignant progression of LCa through the mutual regulation of miR-107. 

Retracted: No

PubPeer comments:
 *[right]* Figs 1D, 3E from [Wu et al (2019)] .  FOXC2-AC1 is highly expressed in lung cancer tissues and cell lines. ... D, Kaplan-Meier survival curve of lung cancer patients was based on FOXC2-AC1 expression ;  FOXC2-AC1 directly targets mir-170. ... E, QRT-PCR verified the interference efficiency of miR-170 after transfection of FOXC2-AC1 overexpression vector in H1299 cell lines and after knockout of FOXC2-AC1 in SPCA1 cell lines. *[left]* Figure 1C from [Wu et al (2020)] .  I call this  Hoya s Law .  When 40 or 50 cases of any given cancer are dichotomised into half-groups of high- or low-expression of any given nc-RNA, survival rate for one or both half-group will drop to 0% at 75 months. I am counting Figs 1D and 3E as separate examples, as the latter seems to have wandered in from a **different paper** being assembled at the same time. The panel specifies  RGS17 , otherwise unmentioned, the caption seems designed for a different figure, and the values in the plots must have come from different data-sets - consider the 70-month values, for instance. Other examples, from left to right: - Fig 1 from [Zang et al (2020)] - Fig 1 from [Li et al (2020)] - Fig 1, and Fig 4D, from [Cui et al (2019)] - Fig 1D from [Gao et al (2019)] .  , 
 #1 *[left]* Figs 1D, 3E from [Wu et al (2019)] .  FOXC2-AC1 is highly expressed in lung cancer tissues and cell lines. ... D, Kaplan-Meier survival curve of lung cancer patients was based on FOXC2-AC1 expression ;  FOXC2-AC1 directly targets mir-170. ... E, QRT-PCR verified the interference efficiency of miR-170 after transfection of FOXC2-AC1 overexpression vector in H1299 cell lines and after knockout of FOXC2-AC1 in SPCA1 cell lines. *[right]* Figs 1D, 4E from [Su Ren (2019)] .  D, Kaplan-Meier survival curves of patients with LCa based on miRNA-199 expression ;  Kaplan-Meier survival curves of patients with LCa based on RGS17 expression . 1D and 1D have stretches of surprising similarity. 3E and 4E are **identical** (apart from a horizontal stretch). One explanation is that both papers emerged from the same studio.  , 
 Fig 2C,  Transwell migration and invasion assays detected the ability of H1299 and SPCA1 cell lines to interfere with FOXC2-AC1 invasion and migration of lung cancer cells.  There are more repeated visual motifs but I ran out of colors. , 
 #2 I noted the resemblance between Figs 3E from this paper, and 4E from [Su Ren (2019)] . Especially striking because one of the papers does not otherwise mention RGC17. The most parsimonious explanation is that a single uncredited studio was involved in the preparation of both papers. We should also compare the present 3D *[above]* and 4D *[below]* from Su Ren.  3 4 of the points are shared. , 
 *[right]* Fig 3D from [Wu et al (2019)] .  There was a significant negative correlation between FOXC2-AC1 and miR-170 expression in lung cancer . *[left]* Fig 3D from [Fan et al (2019)] .  There was a significant negative correlation between the ex-pression levels of GIHCG and miR-1281 in breast cancer tissues.  ,