Bioinformatics evaluation of the target signaling pathways and function of hsa-miR-۲۲۱-۳p on rs۲۶۰۳۷۵۱ SNP within NR۴A۱ gene, associated with triple-negative breast cancer

Background and Aim: Breast cancer poses a major threat to women's health. Triple-negative breast cancer (TNBC), which does not express estrogen α, progesterone and human epidermal growth factor ۲ receptors, comprises ۱۵% of all breast carcinomas. Nuclear receptor ۴A۱ (NR۴A۱) is a member of NR۴A orphan nuclear receptor superfamily. Translocation of the protein from the nucleus to mitochondria induces apoptosis. The role of NR۴A۱ in cancer is currently controversial which could be specific to the types or subtypes of cancers. Besides research confirming the oncogenic role, several studies have reported NR۴A۱ as a tumor suppressor. For instance, induced up-regulation of NR۴A۱ in hepatocytes, leading to the activation of p۵۳, also NR۴A۱ expression has been reduced in TNBC. In the present study, we aimed to investigate non-coding SNP polymorphisms in NR۴A۱ gene which probably influence gene expression in p۵۳ activation pathway.Methods: Online target prediction tools including miRNASNP۲ database were used to identify target SNPs that possibly regulated by MicroRNAs so miRNA hsa-miR-۲۲۱-۳p predicted to target the rs۲۶۰۳۷۵۱ SNP located on ۳’UTR of NR۴A۱ gene. The Frequency of rs۲۶۰۳۷۵۱ SNP and the confirmation of hsa-miR-۲۲۱-۳p activity were respectively investigated by NCBI and miRbase. miRWALK ۲.۰, was used to predict target genes for the hsa-miR-۲۲۱-۳p. The signalling pathways of NR۴A۱ and hsa-miR-۲۲۱-۳p, were investigated by DAVID and KEGG databases.Results: Since rs۲۶۰۳۷۵۱ is located in the ۳UTR region of the NR۴A۱ gene, the binding site of this microRNA is precisely the rs۲۶۰۳۷۵۱ polymorphism region, targeting this polymorphism can regulate NR۴A۱ gene expression in the cancer signalling pathway. Regarding analysis based on miRNASNP۲, it is predicted that hsa-miR-۲۲۱-۳p has the less binding affinity to the wild allele (T) than the mutantrs۲۶۰۳۷۵۱ allele. Due to negative regulatory function of hsa-miR-۲۲۱-۳p, it is expected that the expression of the wild allele of the target gene will be increase and eventually, the p۵۳ signalling pathway becomes more active and more apoptosis occurs.Conclusion: In conclusion, hsa-miR-۲۲۱-۳ may regulate NR۴A۱ gene that is vital for TNBC development and progression, hsa-miR-۲۲۱-۳ and targeting the mutant allele (rs۲۶۰۳۷۵۱), could be as potential biomarkers and therapeutic targets for targeted therapy of TNBC.

Keywords:

triple-negative breast cancer , miRNA , SNP , rs۲۶۰۳۷۵۱ , hsa-miR-۲۲۱-۳p , NR۴A۱