Introduction: MALAT1 is a controversial long-noncoding RNA with different and contrasting roles in breast cancer (BC). This lncRNA is involved in a pro-tumorigenic role in considerable solid tumors, including breast tumors and some lymphoid tumors, and on the contrary, plays an opposing role in the metastasis of breast cancer. Therefore, MALAT1 becomes a conceivable therapeutic target for breast cancer, so it is necessary to thoroughly investigate and comprehend the underlying reasons for the variations observed in MALAT1's role in tumorigenesis and the relationships between this lncRNA and its potential targets, such as microRNAs.
Methods: The RNAseq data of BC and healthy control (103 breast tumor tissue samples and 11 normal) were downloaded from the gene expression synthesis (GEO) GSE68085 (Krishnan P et al., 2016). Data were indexed by Bowtie and analyzed using the R package DESeq2. The transcriptomes of tumor tissue samples and healthy normal breast tissues were compared to identify microRNAs involved in breast cancer. Significant miRNAs (with high targeting scores) associated with long non-coding RNAs were searched through miRDB, starBase, and miRcode tools.
Results: We identified significant (padj <0.01) down-regulated expression of hsa-miR-1271-5p, hsa-miR-383-5p, and hsa-miR-4524a-5p, and up-regulated expression of hsa-miR-101-3p, hsa-miR-185-5p, hsa-miR-503-5p, hsa-miR-651-5p in tomur tissue cells. All of the mentioned microRNAs are potential targets for MALAT1. Three of them are up-regulated, and the others are down-regulated. So investigating the relationship between these miR and MALAT1 in different stages of tumors may help reveal the MALAT1 roles in BC.
Conclusion: All of the mentioned microRNAs are potential targets for MALAT1. Three of them are up-regulated, and the others are down-regulated. So investigating the relationship between these miR and MALAT1 in different stages of tumors may help reveal the MALAT1 roles in BC.
Keywords: MALAT1, breast cancer, miroRNA, noncoding RNA