FXR1 is elevated in colorectal cancer and acts as an oncogene.

Fragile X-related gene 1 (FXR1) is deregulated in a variety of human disorders including cancer. However, there is relatively little evidence concerning the relationship between FXR1 and colorectal cancer. Western blot, immunohistochemistry (IHC), and quantitative real-time PCR (qRT-PCR) were adopted to detect the FXR1 protein and messenger RNA (mRNA) expression, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate the plasma FXR1 expression in our study. MTT assay and colony formation assay were used to examine the proliferation ability of cells in vitro. In addition, Transwell assays were performed to test the migration and invasion abilities of cancer cells. We found that the average plasma FXR1 level in CRC was significantly higher than that in healthy controls (P < 0.001). Moreover, the plasma expression of FXR1 in stage IV patients was dramatically higher than that in stage I, stage II, and stage III patients (P < 0.001). Consistently, FXR1 mRNA expression levels were much higher in cancer tissues than that in normal tissues. Moreover, IHC results showed that cancer tissues possessed higher FXR1 expression (P = 0.027). What's more, plasma FXR1 was a risk factor of colorectal cancer indicated by univariate survival analysis (P = 0.021, HR = 1.685, 95 % CI 1.336-1.927). Multivariate analysis suggested that FXR1 was an independent risk factor of colorectal cancer (P = 0.008, HR = 1.381, 95 % CI 1.119-1.741). Kaplan-Meier analysis showed that the patients with higher plasma FXR1 expression had a poorer outcome (P < 0.001). Besides, FXR1 acted as an oncogene which could increase the proliferation, migration, and invasion of cancer cells. All these data indicate that FXR1 might act as a tumor promoter. Future investigations are warranted to explore whether FXR1 may represent a novel therapeutic target.