Expression and Prognostic Value of RAD51 in Adenocarcinoma at the Gastroesophageal Junction

Background: The RAD51 recombinase is involved in homologous recombination and DNA repair. However, the association of RAD51 with the prognosis of adenocarcinoma at the gastroesophageal junction (ACGEJ) is not clear. We aimed to investigate the association of RAD51with ACGEJ prognosis. Methods: The difference in the expression level of RAD51 between ACGEJ tumors and control tissues in the microarray datasets (GSE159721, GSE74553, and GSE96669) were compared. The online Kaplan-Meier plotter survival analysis and meta-analysis were used to analyze the association of RAD51 with overall survival in pan-cancers. MiRNAs targeting RAD51 were identified and their expression profiles in ACGEJ tumors were analyzed. Functional enrichment analysis was performed for miRNAs of RAD51. Results: RAD51 was upregulated in ACGEJ tumors compared with control tissues (P < 0.05). High RAD51 level was correlated with a poor prognosis in stomach adenocarcinoma and esophageal cancer. The meta-analysis showed that high RAD51 level was correlated with a poor prognosis in TCGA pan-cancers (P = 0.03). Six regulatory miRNAs of RAD51, including hsa-miR-182, hsa-miR-221, and hsa-miR-34a, were downregulated in ACGEJ tumor tissues and were associated with pathways including “fatty acid biosynthesis” and “viral carcinogenesis”. Conclusions: RAD51 is a potent prognostic biomarker in ACGEJ. MiRNAs including hsa-miR-182, hsa-miR-221, and hsa-miR-34a might play crucial roles in ACGEJ by regulating the RAD51 gene.