Lipocalin 2 negatively regulates cell proliferation and epithelial to mesenchymal transition through changing metabolic gene expression in colorectal cancer

Lipocalin 2 (LCN2), a member of the lipocalin superfamily, plays an important role in oncogenesis and progression in various types of cancer. However, the expression pattern and functional role of LCN2 in colorectal cancer (CRC) is still poorly understood. The purpose of the present study was to investigate whether LCN2 is associated with proliferation and the epithelial-mesenchymal transition (EMT) in CRC and to elucidate the underlying signaling pathways. LCN2 was preferentially expressed in CRC cells compared to normal tissues. However, LCN2 expression was significantly lower in metastatic or advanced-stage CRC than in non-metastatic or early stage CRC. Knockdown of LCN2 using small interfering RNA (siRNA) in CRC cells expressing a high level of LCN2 induced cell proliferation and a morphological switch from an epithelial to mesenchymal state. Furthermore, downregulation of LCN2 in CRC cells increased cell migration and invasion involved in the regulation of EMT markers. Knockdown of LCN2 also induced glucose consumption and lactate production, accompanied by an increase in energy metabolism-related genes. Taken together, our findings indicated that LCN2 negatively modulated proliferation, EMT and energy metabolism in CRC cells. Accordingly, LCN2 may be a candidate metastasis suppressor and potential therapeutic target in CRC.