PFKFB2 is a favorable prognostic biomarker for colorectal cancer by suppressing metastasis and tumor glycolysis

Purpose: This study was to investigate the biological effect of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 2 (PFKFB2) in colorectal cancer (CRC).

Methods: PFKFB2 was selected by metabolism polymerase chain reaction (PCR) array from CRC cells under alkaline culture medium (pH 7.4) and acidic culture medium (pH 6.8). The expression of PFKFB2 mRNA and protein was detected by quantitative real-time PCR and immunohistochemistry in 70 paired fresh and 268 paired paraffin-embedded human CRC tissues, respectively, and then the prognostic value of PFKFB2 was investigated. The effects of PFKFB2 on CRC cells were also verified in vitro, which were through detecting the change of migration, invasion, sphere formation, proliferation, colony formation, and extracellular acidification rate of CRC cells after PFKFB2 knockdown in alkaline culture medium (pH 7.4) and overexpression in acidic culture medium (pH 6.8).

Results: PFKFB2 expression was downregulated in acidic culture medium (pH 6.8). In addition, we found PFKFB2 expression decreased in human CRC tissues compared with the adjacent normal tissues. Furthermore, the OS and DFS rate of CRC patients with low PFKFB2 expression was significantly shorter than those of patients with high PFKFB2 expression. Multivariate analysis indicated that low PFKFB2 expression was an independent prognostic factor for both OS and DFS in CRC patients. Moreover, the abilities of migration, invasion, spheroidizing ability, proliferation, and colony formation of CRC cells were significantly increased after depletion of PFKFB2 in alkaline culture medium (pH 7.4) and decreased after overexpression of PFKFB2 in acidic culture medium (pH 6.8) in vitro. Epithelial-mesenchymal transition (EMT) pathway was found and verified involved in the PFKFB2-mediated regulation of metastatic function in CRC cells. Further, glycolysis of CRC cells was significantly elevated after knockdown of PFKFB2 in alkaline culture medium (pH 7.4) and decreased after overexpression of PFKFB2 in acidic culture medium (pH 6.8).

Conclusion: PFKFB2 expression is downregulated in CRC tissues and associated with worse survival for CRC patients. PFKFB2 could inhibit metastasis and the malignant progression of CRC cells by suppressing EMT and glycolysis.