KLF9 (Kruppel Like Factor 9) induced PFKFB3 (6-Phosphofructo-2-Kinase/Fructose-2, 6-Biphosphatase 3) downregulation inhibits the proliferation, metastasis and aerobic glycolysis of cutaneous squamous cell carcinoma cells

Abstract

ABSTRACT Cutaneous squamous cell carcinoma (CSCC) is the second most common skin cancer in humans with increasing incidence. In this paper, we focused on the effects of krueppel-like factor 9 (KLF9) on the progression of CSCC cells by binding to PFKFB3. mRNA and protein expressions of KLF9 and PFKFB3 in human HaCaT and CSCC cells were, respectively, examined by RT-qPCR analysis and Western blot. The viability, proliferation, invasion and migration of A431 cells after transfection were analyzed with MTT, clone formation, transwell and wound healing assays. The levels of glucose, lactic acid and ATP in transfected A431 cells were detected by their commercial kits. Ki-67 expression in transfected A431 cells was determined using immunofluorescence analysis and in tumor tissues was analyzed by immunohistochemistry. The levels of migration, EMT and aerobic glycolysis-related proteins were tested with Western blot. The combination of KLF9 and PFKFB3 was confirmed by dual-luciferase reporter assay and ChIP. As a result, PFKFB3 expression was elevated in CSCC cells compared with HaCaT. Knockdown of PFKFB3 restrained the proliferation, metastasis, and aerobic glycolysis of CSCC cells. In addition, KLF9 could bind to PFKFB3. Downregulation of KLF9 crippled the inhibitory effect of knockdown of PFKFB3 on the proliferation, metastasis, and aerobic glycolysis of CSCC cells. In conclusion, PFKFB3 was transcriptionally regulated by KLF9, and PFKFB3 silencing inhibits the proliferation, metastasis, and aerobic glycolysis of cutaneous squamous cell carcinoma cells.