Expression and function analysis of CRABP2 and FABP5, and their ratio in esophageal squamous cell carcinoma

Objective The purpose of this study was to explore the effect of CRABP2 and FABP5, and their ratio on prognosis in esophageal squamous cell carcinoma. Methods The expression data of CRABP2 in esophageal cancer in TCGA and GEO were collected by the public database GEPIA. The expression levels of CRABP2 and FABP5 were examined using immunohistochemistry. The relationship between the two proteins and related clinicopathological parameters were analyzed by χ2 test. Survival analysis was used to investigate the effect of CRABP2 and FABP5, and their ratio on prognosis. Results Compared with normal esophageal mucosal epithelium, there was lower CRABP2 gene mRNA in the esophageal cancer tissue, and the difference was statistically significant (p < 0.01). For the expression level, no significant difference was observed in patients with stages I-IV in esophageal cancer. Immunohistochemistry showed that CRABP2 and FABP5 were both highly expressed in normal esophageal squamous epithelial cells at 100 and 94.1%, while lower in ESCC (75.6 and 58.7%). There was a significant difference in the expression between cancer and adjacent tissues (p < 0.001). No inherent relationship was manifested between the CRABP2 expression and the clinical parameters of the ESCC. The expression of FABP5 was related to lymph node metastasis (p = 0.032), the depth of invasion (p = 0.041), and the AJCC stage (p = 0.013). The ratio of CRABP2 and FABP5 was related to ethnicity (p = 0.001), nerve invasion (p = 0.031), and postoperative treatment (p = 0.038). CRABP2 is positively associated with FABP5 (r = 0.156, p = 0.041) and the ratio (r = 0.334, p = 0.000), while there was a negative correlation between FABP5 and the ratio (r = -0.269, p = 0.000). Patients with CRABP2-positive expression had a significantly longer overall survival than patients with CRABP2-negative expression (p = 0.025). Conclusion CRABP2 as a suppressor factor is expected to be a potential prognosis marker for esophageal squamous cell carcinoma.