PGC1α Cooperates with FOXA1 to Regulate Epithelial Mesenchymal Transition through the TCF4-TWIST1

TGF-β1 facilitates gallbladder carcinoma metastasis by regulating FOXA1 translation efficiency through m6A modification

TGF-β1 plays a pivotal role in the metastatic cascade of malignant neoplasms. N6-methyladenosine (m6A) stands as one of the most abundant modifications on the mRNA transcriptome. However, in the metastasis of gallbladder carcinoma (GBC), the effect of TGF-β1 with mRNA m6A modification, especially the effect of mRNA translation efficiency associated with m6A modification, remains poorly elucidated. Here we demonstrated a negative correlation between FOXA1 and TGF-β1 expression in GBC. Overexpression of FOXA1 inhibited TGF-β1-induced migration and epithelial-mesenchymal transition (EMT) in GBC cells. Mechanistically, we confirmed that TGF-β1 suppressed the translation efficiency of FOXA1 mRNA through polysome profiling analysis. Importantly, both in vivo and in vitro experiments showed that TGF-β1 promoted m6A modification on the coding sequence (CDS) region of FOXA1 mRNA, which was responsible for the inhibition of FOXA1 mRNA translation by TGF-β1. We demonstrated through MeRIP and RIP assays, dual-luciferase reporter assays and site-directed mutagenesis that ALKBH5 promoted FOXA1 protein expression by inhibiting m6A modification on the CDS region of FOXA1 mRNA. Moreover, TGF-β1 inhibited the binding capacity of ALKBH5 to the FOXA1 CDS region. Lastly, our study confirmed that overexpression of FOXA1 suppressed lung metastasis and EMT in a nude mice lung metastasis model. In summary, our research findings underscore the role of TGF-β1 in regulating TGF-β1/FOXA1-induced GBC EMT and metastasis by inhibiting FOXA1 translation efficiency through m6A modification.

In vitro study of miRNA-369-3p targeting TCF4 regulating the malignant biological behavior of colon cancer cells

Background

Colorectal carcinoma (CRC) is a common malignant tumor of the digestive tract. It is characterized by a high degree of malignancy, early metastasis and poor prognosis. Studies have shown the effect of miR-369-3p on the biological function of a variety of tumors. However, the mechanism by which miR-369-3p and its potential target genes participate in the pathogenesis of CRC has not been elucidated. This study aims to study the relationship between miR-369-3p and transcription factor 4 (TCF4), to reveal the mechanism of the occurrence and development of CRC, and to provide a promising target for the treatment of CRC.

Methods

Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the miR-369-3p levels in CRC tissues and cells. miR-369-3p mimics and/or TCF4 overexpression vectors were transfected into SW480 cells. The expression of miR-369-3p and TCF4 mRNA was detected using RT-qPCR. Bioinformatics analysis predicted the binding site of miR-369-3p to the TCF4 3'UTR, and the targeting relationship was verified by a dual luciferase reporter gene assay. Cell proliferation and invasion were investigated by labeled immunofluorescence assay using BrdU antibody and Transwell assay. The oxidative stress ability of cells was determined by commercial kits. The levels of proteins related to cell proliferation and invasion were measured by western blotting.

Results

The level of miR-369-3p was significantly down-regulated in CRC tissues and cell lines, especially in SW480 cells (P<0.05). The expression of TCF4 was negatively correlated with that of miR-369-3p. High levels of miR-369-3p targeting TCF4 suppressed cell proliferation and downregulated the protein expression of Ki67 and PCNA (P<0.05). Overexpressed miR-369-3p binding TCF4 inhibited cell invasion and decreased the protein levels of vascular endothelial growth factor (VEGF) and E-cadherin (P<0.05). Furthermore, upregulation of miR-369-3p increased the activity of superoxide dismutase (SOD) while decreasing the content of malondialdehyde (MDA) and activity of lactate dehydrogenase (LDH) by blocking the expression of TCF4 (P<0.05).

Conclusions

MiR-369-3p inhibits the proliferation, invasion and oxidative stress of CRC cells by targeting TCF4, thus defining miR-369-3p as a potential target for the diagnosis and treatment of CRC.

Knockdown of PGC1α suppresses dysplastic oral keratinocytes proliferation through reprogramming energy metabolism

Oral potentially malignant disorders (OPMDs) are precursors of oral squamous cell carcinoma (OSCC). Deregulated cellular energy metabolism is a critical hallmark of cancer cells. Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC1α) plays vital role in mitochondrial energy metabolism. However, the molecular mechanism of PGC1α on OPMDs progression is less unclear. Therefore, we investigated the effects of knockdown PGC1α on human dysplastic oral keratinocytes (DOKs) comprehensively, including cell proliferation, cell cycle, apoptosis, xenograft tumor, mitochondrial DNA (mtDNA), mitochondrial electron transport chain complexes (ETC), reactive oxygen species (ROS), oxygen consumption rate (OCR), extracellular acidification rate (ECAR), and glucose uptake. We found that knockdown PGC1α significantly inhibited the proliferation of DOKs in vitro and tumor growth in vivo, induced S-phase arrest, and suppressed PI3K/Akt signaling pathway without affecting cell apoptosis. Mechanistically, downregulated of PGC1α decreased mtDNA, ETC, and OCR, while enhancing ROS, glucose uptake, ECAR, and glycolysis by regulating lactate dehydrogenase A (LDHA). Moreover, SR18292 (an inhibitor of PGC1α) induced oxidative phosphorylation dysfunction of DOKs and declined DOK xenograft tumor progression. Thus, our work suggests that PGC1α plays a crucial role in cell proliferation by reprograming energy metabolism and interfering with energy metabolism, acting as a potential therapeutic target for OPMDs.

Protein stabilization of ITF2 by NF-κB prevents colitis-associated cancer development

Chronic colonic inflammation is a feature of cancer and is strongly associated with tumorigenesis, but its underlying molecular mechanisms remain poorly understood. Inflammatory conditions increased ITF2 and p65 expression both ex vivo and in vivo, and ITF2 and p65 showed positive correlations. p65 overexpression stabilized ITF2 protein levels by interfering with the binding of Parkin to ITF2. More specifically, the C-terminus of p65 binds to the N-terminus of ITF2 and inhibits ubiquitination, thereby promoting ITF2 stabilization. Parkin acts as a E3 ubiquitin ligase for ITF2 ubiquitination. Intestinal epithelial-specific deletion of ITF2 facilitated nuclear translocation of p65 and thus increased colitis-associated cancer tumorigenesis, which was mediated by Azoxymethane/Dextran sulfate sodium or dextran sulfate sodium. Upregulated ITF2 expression was lost in carcinoma tissues of colitis-associated cancer patients, whereas p65 expression much more increased in both dysplastic and carcinoma regions. Therefore, these findings indicate a critical role for ITF2 in the repression of colitis-associated cancer progression and ITF2 would be an attractive target against inflammatory diseases including colitis-associated cancer.