Bioinformatic analysis of neuropeptide related genes in patients diagnosed with invasive breast carcinoma.

Purpose: Neuropeptide receptors are expressed in many malignancies. Effectors involved in the action mechanisms of HCRTR1, HCRTR2, NPY4R (PPYR1) may be related to breast cancer (BC). Genes encoding these receptors and PPY and PTPN11 genes were aimed to examine via bioinformatics tools in the BRCA cohort. To our knowledge, this is the first study in which these receptor genes and PP, which have not found much research in BC, are examined together with PTPN11 and analyzed comprehensively in large patient cohorts from public databases.

Methods: cBioPortal was used for gene alteration analyses, GeneMania for association analyses with other genes, Kaplan-Meier Plotter for Overall Survival (OS) and Relapse Free Survival (RFS) analyses, UALCAN for methylation analyses, TIMER2.0 for expression analyses, The Human Protein Atlas database for expression validations, TIMER for immune infiltration analyses, WEKA 3.8.6 for diagnostic classification performances of the genes based on Random Forest Classifier and Enrichr-KG for Gene Ontology (GO) Biological Process (BP) and KEGG analysis.

Results: 19 (1.9 %) nucleotide changes were found in 996 cases. Missense mutation is most common. Decreased expression levels of the HCRTR1 gene were associated with shorter OS and RFS, but decreased expression levels of the PTPN11 gene were associated with longer OS and RFS. Decreased expression levels NPY4R (PPYR1) gene were associated with shorter RFS. Increased expression levels of HCRTR2 and PPY genes were associated with longer RFS. HCRTR1 and NPY4R (PPYR1) genes were statistically hypermethylated; conversely HCRTR2 and PPY genes were hypomethylated. There was no significant change in PTPN11 gene promoter methylation level. HCRTR1, NPY4R (PPYR1) and PTPN11 gene expressions were downregulated; conversely, HCRTR2 and PPY gene expressions upregulated. Weak correlations were observed between NPY4R (PPYR1) gene expression and CD4 T Cell, Neutrophil, Dendritic Cell and between PTPN11 gene expression and CD8 T Cell, Macrophage, Neutrophil, Dendritic Cell infiltrations. Area under the receiver operating characteristics curve values of the 10-fold cross-validation and by splitting the dataset in a ratio of 80:20 models were 0.930 and 0.963 respectively. HCRTR2 and HCRTR1 belong to regulation of cytosolic calcium ion concentration, cellular calcium ion homeostasis GO BPs.

Conclusion: In BC patients, increases in HCRTR2 and PPY gene expressions could be considered as positive prognostic factors. Decreases in HCRTR1 and NPY4R (PPYR1) gene expressions could be considered as negative prognostic factors. Decreased expression of PTPN11 gene may have a positive prognostic factor. Changes in existing genes are likely to be both a biomarker and therapeutic target for BC. However, experimental and clinical studies are needed to elucidate the mechanisms underlying these neuropeptide receptors in terms of breast carcinogenesis.