FOXP3 promotes colorectal carcinoma liver metastases by evaluating MMP9 expression via regulating S-adenosylmethionine metabolism
Authors: Jingdong Zhang
Zhe Wang
Journal: Annals of translational medicine (2020)
Discipline: CLINICAL MEDICINE
Keywords: Colorectal carcinoma (CRC); FOXP3; MMP9; liver metastasis; metabolomics
Affiliations: Medical Oncology Department of Gastrointestinal Cancer, Liaoning Cancer Hospital & Institute, Cancer Hospital of China Medical University, Shenyang 110042, China.

Abstract:  Background: Growing evidence has proved that Forkhead box protein 3 (FOXP3), which is a master regulatory gene in the development and function of regulatory T-cells, is expressed in human cancer cells. This expression indicates the crucial role FOXP3 takes up as the disease progresses. However, its role in colorectal cancer (CRC) liver metastasis is still mostly unknown. This study set out to explore the molecular characteristics of FOXP3 in driving the liver metastasis within CRC. Methods: We downloaded the RNA-seq data from the GSE50760. Weighted gene co-expression network analysis (WGCNA)WGCNA and RNA-Seq analysis were applied to find the key gene network associated with colorectal cancer liver metastasis. Then we performed pathway enrichment analysis on liver metastasis-associated gene set. Immunohistochemistry, in vitro and in vivo studies were conducted to test expression and function of FOXP3 in CRC tissues and liver metastasis tissues. Non-targeted metabolomics analysis was performed to identify the alteration of FOXP3 expression in metabolites of colorectal cancer liver metastasis. Western blot was performed to confirm changes of matrix metalloproteinase 9MMP9 expression were downstream events of S-adenosyl-methionine (SAM). Results: We found that FOXP3 and MMP9 exhibited co-expression relationships and affected liver metastasis in CRC. Upregulation of FOXP3 promotes cell migration and invasion in CRC, which suggests a pro-cancer effect. Moreover, metabolomics analysis showed that knockdown of FOXP3 significantly reduced SAM levels, and changes of MMP9 expression were downstream events of SAM, which is concentration-dependent. Besides, The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Western blot analysis confirmed that overexpression of FOXP3 activates the Wnt pathway to promote colon cancer metastasis. Conclusions: Our results altogether suggested that FOXP3 expression inhibited the SAM cycle to reduce SAMe levels, resulting in altered MMP9 expression and helped CRC liver metastasis. 

Retracted: No

PubPeer comments:
 In this paper, there is what appears to be a duplicated panel in figure 3 (boxed below). The panels are supposed to represent spinal cords from different fish, treated with different morpholinos, therefore, should not be identical. ![file] I also have a concern with figure 1A in this paper. Here, supposedly the same larval fish are shown 12 hours apart, with (shrinking) lesion sites shown boxed in red by the authors. Outside the boxes, the fish look absolutely identical, down to the shapes of notochord cells and position of blood cells in vessels (boxed by me in light blue). Can the authors explain how this astonishing similarity has come about? ![file] , 
 In this paper, there is what appears to be a duplicated panel in figure 3 (boxed below). The panels are supposed to represent spinal cords from different fish, treated with different morpholinos, therefore, should not be identical. Our response: Yes, unintentionally, one panel got duplicated while arranging the figure 3 in Abode Illustrator. We apologize for the oversight. I also have a concern with figure 1A in this paper. Here, supposedly the same larval fish are shown 12 hours apart, with (shrinking) lesion sites shown boxed in red by the authors. Outside the boxes, the fish look absolutely identical, down to the shapes of notochord cells and position of blood cells in vessels (boxed by me in light blue). Can the authors explain how this astonishing similarity has come about? Our response: The process of tissue repair was followed 12 h apart after SCI in the same fish. Fish were monitored individually over this time period by repeated embedding to immobilize the fish and release from the agarose to allow them to swim freely. While taking the picture more preciseness were considered such as distance from proximal and distal to lesion site, lesion centre, pigmentation and notochord positioning. In these figures, the potion adjacent to spinal cord was left out and rest were cropped out. Our method using the 2-photon laser allowed complete transection of the spinal cord without inducing injury next to the lesion site or injury of other than neural tissues and did not lead to structural abnormalities of the fish or cause them to die, allowing the fish to keep a normal and straight body shape after SCI. ,