12-Lipoxygenase promotes epithelial-mesenchymal transition via the Wnt/β-catenin signaling pathway in gastric cancer cells

Background

12-Lipoxygenase (12-LOX) plays a major role in the progression and metastasis of various types of cancer. In gastric cancer (GC), the expression level of 12-LOX is significantly up-regulated; however, its function, and underlying mechanism of action remain unclear.

Methods

The mRNA and protein expression levels of 12-LOX were assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analyses, respectively, in GC cell lines. 12-LOX expression was stably up-regulated using lentiviral vector in BGC823 and MGC803 cells, and cell-counting kit-8 (CCK8), colony formation, and invasion assays were performed to verify the function of 12-LOX in proliferation and metastasis. In addition, the expression levels of epithelial-mesenchymal transition (EMT) differentiation markers and downstream targets of the Wnt/β-catenin signaling pathway were examined by Western blotting. A nude mouse model of tumor growth and metastasis was established to investigate the role of 12-LOX in vivo.

Results

Our findings demonstrate that 12-LOX mRNA and protein were highly expressed in GC cell lines. 12-LOX overexpression promoted GC cell proliferation, migration, and invasion both in vitro and in vivo. In addition, up-regulation of 12-LOX promoted the EMT in GC cells, as reflected by a decrease in E-cadherin expression and an increase in N-cadherin and Snail expression. 12-LOX overexpression in GC cells also increased the expression of multiple downstream targets of the Wnt/β-catenin signaling pathway.

Conclusion

These findings revealed that 12-LOX functions as an oncogene in promoting GC cell proliferation and metastasis in vitro and in vivo. In addition, 12-LOX might regulate the EMT via the Wnt/β-catenin signaling pathway, indicating a potential role for 12-LOX as a target in GC treatment.

Biomarkers of epithelial-mesenchymal transition in gastric cancer

In gastric cancer, metastases are the major cause of death. Understanding the mechanism by which tumor cells invade and metastasize is essential to develop novel treatments for gastric cancer (GC). Epithelial-mesenchymal transition (EMT) is a multistage process in which epithelial cells develop into mesenchymal-like cells with a large number of distinct genetic and epigenetic alterations. EMT also occurs in cancer, which endows invasive and metastatic properties upon cancer cells that favor successful colonization of distal target organs. Here, we summarize studies of known EMT biomarkers in the context of GC progression. The biomarkers discussed include cell-surface proteins (E-cadherin and N-cadherin), cytoskeletal proteins (β-catenin and Vimentin), and transcription factors (Snail, Twist, ZEB1 and ZEB2).