Expression of Fibulin-2 in Colorectal Cancer and its Effect on Tumor Invasion and Metastasis / 胃肠病学

ABSTRACT

Background: Colorectal cancer (CRC) is one of the most common cancers in China and even in the world, and metastasis is the main cause of death. However, there is lack of sufficient molecular biomarkers for predicting effectively the occurrence of metastasis. Aims: To explore the expression of fibulin-2 (FBLN2) in CRC and the underlying mechanism of its effect on tumor invasion and metastasis. Methods: Bioinformatics data of PRJNA218851 data set from the SRA database were extracted to screen CRC metastasis-associated genes. Then these differentially expressed genes were applied for gene enrichment analysis to identify the most significant pathways. Data from TCGA and clinical CRC samples were used to analyze the expression of FBLN2 in CRC tissues and normal tissues, and the relationship between FBLN2 and clinicopathological features and prognosis of CRC patients. Expression of FBLN2 in normal colorectal mucosal cell line, CRC cell lines, and clinical CRC samples was detected by real-time PCR. After FBLN2 was knockdown or over expressed in CRC cells, CCK-8 assay, clone formation assay, Transwell cell invasion and migration assay, and wound healing assay were performed to observe the effect of FBLN2 on the proliferation, invasion and migration abilities of CRC cells. Gene set enrichment analysis was conducted to screen the potential downstream pathway of FBLN2, and then the pathway screened was verified. Results: The expression of FBLN2 was low in eight CRC cell lines and CRC tissues, yet the expression in metastatic CRC was significantly higher than that in non-metastatic ones. Compared with CRC patients with low FBLN2 expression, CRC patients with high FBLN2 expression were prone to have lymph node metastasis and distant metastasis, and with higher clinical stage and poorer prognosis. Knockdown of FBLN2 could decrease the invasion and migration abilities of CRC cells, but had no impact on cell proliferation. FBLN2 was positively correlated with CDH2, Snai1 and vimentin, indicating that the epithelial-mesenchymal transition (EMT) pathway might be the downstream pathway of FBLN2. Conclusions: FBLN2 is low expressed in CRC but the expression is increased in metastatic CRC. Therefore, it might be used as a molecular biomarker for screening early metastasis. FBLN2 might enhance CRC invasion and metastasis through activating EMT pathway and is associated with poor prognosis.