Renal fibrosis is recognized as a critical pathway leading to end-stage renal disease in nearly all cases of chronic kidney disease (CKD). Analysis of the gene expression omnibus (GEO) database revealed that the transcription factor Krüppel-like factor 3 (KLF3) was elevated in kidney tissues of CKD patients, however, its specific role in CKD-associated renal fibrosis is yet to be deciphered. This study aimed to investigate the function of KLF3 on unilateral ureteral obstruction (UUO) mice and transforming growth factor-β1 (TGF-β1)-stimulated HK2 cells. Our data demonstrated that KLF3 was remarkably upregulated in the renal cortex of UUO mice and TGF-β1-treated HK-2 cells. We further confirmed that the upregulation of KLF3 was associated with its N6-methyladenosine (m6A) methylation modification. Knockdown of METTL14 reduced m6A methylation level of KLF3 and inhibited its mRNA stability. In vivo results suggested that KLF3 knockdown alleviated the pathological changes in renal tissues triggered by UUO. Additionally, KLF3 silencing mitigated renal fibrosis both in vivo and in vitro , as accompanied by decreased expression of Collagen I, Vimentin, α-SMA and Fibronectin. Mechanistically, KLF3 transcription activated dimethylarginine dimethylaminohydroxylase 2 (DDAH2) and upregulated its expression. Rescue experiments substantiated that DDAH2 overexpression eliminated the effect of KLF3 knockdown on renal fibrosis. Collectively, our findings suggest that inhibition of KLF3 may serve as a potential strategy to prevent CKD-associated renal fibrosis.
Background Osteosarcoma (OS) is a highly recurrent malignancy occurring among adolescents. The goal of this research was to scrutinize the role and action mechanism of KLF3-AS1 in OS. Methods Western blotting and quantitative reverse transcription real-time PCR were conducted to ascertain the mRNA expressions of miR-338-3p, KLF3-AS1, and MEF2C in OS cell lines and tissue samples. Colony formation and CCK-8 experiments were done to evaluate the proliferative capacity of the cells. Western blotting was also executed to measure the relative expressions of the proteins Bcl-2 and Bax. RNA immunoprecipitation and dual luciferase reporter experiments were carried out to validate the target relationships among MEF2C, KLF3-AS1, and miR-338-3p. Mouse xenograft models were created to assess the influences of KLF3-AS1 on the growth of tumors in vivo. Results Elevated levels of KLF3-AS1 and MEF2C and reduced amounts of miR-338-3p were identified in OS. KLF3-AS1 targeted miR-338-3p, and miR-338-3p further targeted MEF2C. Silencing KLF3-AS1 induced apoptosis and attenuated proliferation in vitro and repressed the tumor growth in vivo. Inhibiting miR-338-3p inverted the cancer-suppressing effects of KLF3-AS1 silencing. Meanwhile, loss of MEF2C partially eliminated the effects brought about by miR-338-3p downregulation, namely the stimulation of cell growth and suppression of apoptosis. Conclusions Silencing of KLF3-AS1 could repress the growth of cells and induce apoptosis by regulating miR-338-3p/MEF2C in OS. This suggests that the regulatory axis KLF3-AS1/miR-338-3p/MEF2C is a prospective target for OS treatment.
The transcription factor Krüppel-like factor (KLF) 3 is one of the members of the KLF family, which plays an important role in tumor progression. Nevertheless, the role of KLF3 in the growth and metastasis of gastric cancer (GC) still needs to be elucidated. Bioinformatics analysis showed that KLF3 was overexpressed in patients with GC, and the high expression of KLF3 was correlated with poor survival. KLF3 was also overexpressed in GC clinical samples and cell lines. In vitro functional role of KLF3 in GC cells was explored by a gain-of-function and loss-of-function assay. Overexpressed KLF3 promoted the cell proliferation, migration, invasion, and epithelial-mesenchymal transition of GC cells, whereas suppressed KLF3 inhibited these biological behaviors. The clinical samples and bioinformatics analysis showed that WNT1 was also highly expressed in GC tumor tissues and positively correlated with KLF3 expression. The luciferase reporter assay and chromatin immunoprecipitation result confirmed that KLF3 could directly bind to the WNT1 promoter to increase the transcriptional activity of WNT1, thus regulating its expression. Overexpressed KLF3 enhanced the protein expression level of p-GSK3β(Ser9) and β-catenin, the key elements in the WNT/β-catenin signaling pathway. Repression of KLF3 decreased the level of p-GSK3β(Ser9) and β-catenin. Immunofluorescence images showed that KLF3 promoted nuclear β-catenin accumulation. Inhibition of WNT1 attenuated the proliferation, migration, and invasiveness of KLF3-overexpressing GC cells. Moreover, the xenograft mouse model confirmed that KLF3 promotes GC tumor growth and metastasis in vivo. Our results demonstrated that KLF3 activates the WNT/β-catenin signaling pathway via WNT1 to promote GC tumor growth and metastasis, indicating that repression of KLF3 may act as a potential therapeutic target for patients with GC.
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