Abstract
BACKGROUND: The present research was designed to study the associations between genetic variants of TYMS and ENOSF1 genes with TYMS and ENOSF1 gene expression in neoadjuvant chemotherapy response among patients with gastric cancer. METHODS: Formalin-embedded and paraffin-fixed matched tumor and normal gastric cancer tissue samples from patients who received neoadjuvant 5-fluorouracil (5-FU) treatment were obtained. DNA and RNA were extracted for all samples. A 28-bp variable number tandem repeat (VNTR) at the 5' untranslated region of TYMS gene and rs2612091 and rs2741171 variants in the ENOSF1 gene were genotyped for normal tissue samples. The real-time polymerase chain reaction method was used to study the expression of ENOSF1 and TYMS genes in both normal and tumor tissues. Data were analyzed using REST 2000 and SPSS ver. 26.0 software programs. RESULTS: A significant association between TYMS 2R3R VNTR genotypes and 5-FU therapy was found (p = .032). The 3R3R and 2R2R genotypes were significantly associated with increased and decreased survival time, respectively (p = .003). The 3R3R genotype was significantly associated with TYMS overexpression (p < .001). Moreover, a significant association was found between the rs2612091 genotype and treatment outcome (p = .017). CONCLUSIONS: This study highlights the impact of TYMS and ENOSF1 genes as predictive indicators for survival and response to 5-FU-based neoadjuvant chemotherapy in gastric cancer patients.