Lack of Association between Epidermal Growth Factor or Its Receptor and Reflux Esophagitis, Barrett's Esophagus, and Esophageal Adenocarcinoma: A Case-Control Study

Abstract

The epidermal growth factor (EGF) and its receptor (EGFR) gene-gene interactions were shown to increase the susceptibility to esophageal cancer. However, the role of the EGF/EGFR pathway in the development of gastroesophageal reflux disease (GERD) and its complications (reflux esophagitis (RE), Barrett's esophagus (BE), and esophageal adenocarcinoma (EAC)) remains unclear. This association study is aimed at investigating functional EGF and EGFR gene polymorphisms, their mRNA expression in esophageal tissues, and EGF plasma levels in relation to RE, BE, and EAC development in the Central European population. 301 patients with RE/BE/EAC (cases) as well as 98 patients with nonerosive reflux disease (NERD) and 8 healthy individuals (controls) were genotyped for +61 A>G EGF (rs4444903) and +142285 G>A EGFR (rs2227983) polymorphisms using the TaqMan quantitative polymerase chain reaction (qPCR). In random subgroups, the EGF and EGFR mRNA expressions were analyzed by reverse transcription qPCR in esophageal tissue with and without endoscopically visible pathological changes; and the EGF plasma levels were determined by enzyme-linked immunosorbent assay. None of the genotyped SNPs nor EGF-EGFR genotype interactions were associated with RE, BE, or EAC development (p > 0.05). Moreover, mRNA expression of neither EGF nor EGFR differed between samples of the esophageal tissue with and without endoscopically visible pathology (p > 0.05) nor between samples from patients with different diagnoses, i.e., RE, BE, or EAC (p > 0.05). Nevertheless, the lower EGF mRNA expression in carriers of combined genotypes AA +61 EGF (rs4444903) and GG +142285 EGFR (rs2227983; p < 0.05) suggests a possible direct/indirect effect of EGF-EGFR gene interactions on EGF gene expression. In conclusion, EGF and EGFR gene variants and their mRNA/protein expression were not associated with RE, BE or EAC development in the Central European population.

Figure 1

The function of studied polymorphisms based on previous studies; allele A of +61 A>G epidermal growth factor (rs4444903) polymorphism leads to a reduction of EGF mRNA expression, and allele G of +142285 G>A EGF receptor (EGFR, rs2227983) polymorphism increases the activity of EGFR [24, 25].

Figure 2

Violin plots of the differences in mRNA expression of the epidermal growth factor (EGF) and its receptor (EGFR) in the tissues with/without visible pathological changes among patients (n = 23) with reflux esophagitis (RE), Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). p > 0.05 Wilcoxon signed ranked test was used.

Figure 3

Violin plot of epidermal growth factor (EGF) plasma levels in 29 patients with gastroesophageal reflux disease (GERD), of which 10 suffered from reflux esophagitis (RE), 9 from Barrett's esophagus (BE), and 10 from esophageal adenocarcinoma (EAC), and 8 were healthy individuals (healthy controls, HC). p > 0.05; Wilcoxon signed ranked test was used.

Figure 4

Violin plots of the differences in mRNA expression of the epidermal growth factor (EGF) and its receptor (EGFR) in the tissues with/without visible pathological changes from patients with gastroesophageal reflux disease (n = 23) divided into two groups according to their EGF-EGFR genotypes: +61 A>G EGF (rs4444903) and +142285 EGFR G>A (rs2227983) Kruskal-Wallis or Mann–Whitney tests were used.