We found that overexpressing miR-139-5p restrained aerobic glycolysis, suppressing proliferation, migration, and invasion in HCC cells. miR-139-5p regulated hexokinase 1 (HK1) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) expression by directly targeting the transcription factor ETS1, which bound to the promoters of the HK1 and PFKFB3 genes. miR-139-5p-induced aerobic glycolysis, proliferation, migration, and invasion were reversed by ETS1 overexpression, while ETS1 silencing induced the expression of miR-139-5p via a post-transcriptional regulation mode involving Drosha. miR-139-5p expression was reduced in HCC compared to para-carcinoma tissue, which was confirmed in The Cancer Genome Atlas and GSE54751 HCC cohorts.
Given the known regulatory role of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase-3 (PFKFB3) in glycolysis and association of glycolytic activity with malignant features such as invasion, we sought to investigate whether TGFβ1 regulates PFKFB3 expression and if PFKFB3 is involved in the TGFβ1-mediated increase in the invasive ability of the Panc1 cell cline-a well-established model of TGFβ1-initiated EMT.
Further studies showed that overexpression of miR-26b repressed PFKFB3 mRNA and protein levels followed by modulation of the expression of glycolytic components (LDHA, GLUT-1) and markers of invasion and cell cycle such as MMP-9, MMP-2, cyclin D1 and p27.