Colorectal cancer (CRC) was the most common gastrointestinal cancer, which represented 1.8 million cases and 881,000 deaths globally, accounting for one tenth of cancer cases and deaths [1]. In high income countries, colorectal cancer incidence rate is largely stabilized or been in decreasing, incidence rate seems to be increasing among adults younger than 50 years. This rising trend may be related to genetic, lifestyle, obesity and environmental factors, but the exact reason is not completely clear. [3].Recent studies have provided new treatment options for CRC. Although these new treatments have doubled the overall survival rate of patients with advanced diseases, the survival rate is still lower than those without metastasis. In order to improve the incidence rate of early colon cancer and reduce its morbidity and mortality, the worldwide screening program is being implemented.[2].
6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFK-2/FBPase 3, PFKFB3) is a member of a bifunctional enzyme family (PFKFB1-4) [4], which contorls the intracellular concentration of fructose 2,6-bisphosphate(F2,6P2) [5]. F2,6BP is a potent actibator of PFK-1, and PFK-1 is essential for the rate-limiting step of glycolysis [6]. The bifunctional isoenzyme encoded by the PFKFB3 gene has the highest kinase: phosphatase activity ratio, which helps to maintain a high rate of glycolysis in cells [7, 8]. According to previous studies, the expression of PFKFB3 gene can be regulated by different mechanisms such as signal pathways, oncogenes, noncoding RNAs, inflammatory molecules, and the PFKFB3 protein can be regulated both at the transcriptional and post-transcriptional levels [9]. Although the glycolytic role of PFKFB3 in cancer progression has been the main field of numerous functional studies, some researchers have also focused on the functions of PFKFB3 beyond glycolysis [10, 11]. Recent studies have shown that the expression of PFKFB3 is crucial not only for the regulation of cytoplasmic glycolysis, but also for the control of nuclear cell cycle and anti-apoptosis. [12, 13]. PFKFB3 has been suggested to play a crucial role in many types of tumor cells as well as various cells in the tumor microenvironment.
miRNAs, a class of noncoding RNA (ncRNA) about 22–24 nucleotide RNAs in size, are involved in the regulation of post transcriptional gene expression in animals and plants by binding to the 3’-untranslated region (3’-UTR) of target mRNAs [14] and participating tumorigenesis, proliferation, invasion and drug resistance in cancer [15].
miR-133a-3p, which belongs to the miR-133 family, was first experimentally characterized in mice [16]. miR-133a-3p is a multicopy gene in the human genome, with two copies: miR-133a-1 and miR-133a-2. To date, multiple functional roles of miR-133a-3p have been elucidated, such as regulating myoblast proliferation and differentiation [17], inhibiting embryonic cardiomyocyte proliferation [18]and avoiding genetic cardiac hypertrophy [19].Furthermore, it has been reported that miR-133a-3p is among the most frequently downregulated miRNAs in various types of human malignancies, which suggested that miR-133a-3p may serve a critical part in tumor progression of various malignancies, including non-small cell cancer [20], ovarian cancer [21], colorectal cancer [22], bladder cancer [23], breast cancer [24] and prostate cancer [25].
In this study, we predicted PFKFB3 was a target gene of miR-133a-3p by bioinformatics analysis. qRT-PCR, western blot and luciferase assays were used to verify the relationship between PFKFB3 and miR-133a-3p, and CCK8 assay and transwell assay were applied to elucidate the effect of the miR-129-5p/PFKFB3 axis on the occurrence and development of CRC. Overall, our results demonstrated that miR-133a-3p suppresses the progression of GCs by targeting PFKFB3.