Bioinformatics analysis of the diagnostic significance and functions of RDH5 in breast cancer

Objective: RDH5 (Retinol dehydrogenase 5) is one of the member of the short-chain dehydrogenase/reductase (SDR) family and plays a critical role in a variety of tumor processes. In this study, we analyzed the expression, diagnostic significance and gene function of RDH5 in breast cancer. Methods: The Gene Expression Profiling Interactive Analysis (GEPIA) database was used to determine the diagnostic and prognostic value of RDH5 and the University of Alabama at Birmingham (UALCAN) database analyzed its expression in different subtypes, clinical stages and altered signal pathways in breast cancer. Then we explored the co-expression gene of RDH5 in breast cancer and constructed its corresponding network through the cBioPortal database. The String database was used to determine its interactions with other proteins. Results: RDH5 expression was differentiated in various tumours compared to normal tissue, and was down-regulated in breast cancer tissue and different subtypes of breast cancer. There was no correlation between RDH5 and the survival of breast cancer. RDH5 expression was significantly associated with different clinical parameters. Additionally, the protein expression of RDH5 in breast cancer with altered pathways indicated it was closely associated with the SWI-SNF (switching/sucrose non-fermenting) complex status and the mammalian Target of Rapamycin (mTOR), WNT (Wingless/Integrated), MYC/MYCN (Myelocytomatosis oncogene/euroblastoma derived MYC), RTK (receptor Tyrosine kinases), and p53/Rb (tumor protein p53/Retinoblastoma) pathways. Interaction analysis with RDH5 and its co-expression genes showed that its main related functions were ethanol oxidation, regulation of heart contraction and negative regulation of tumor necrosis factor. Lastly, the Protein-protein interaction (PPI) of RDH5 showed that the most relevant Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were retinol metabolism, vitamin digestion and absorption and metabolic pathways. Conclusion: These results implied that RDH5 might be a larvaceous diagnostic biomarker for breast cancer and was closely associated with its metabolism. However, more studies are needed to confirm our findings and support the clinical importance of RDH5 in breast cancer.