A panel of four miRNAs (miR-190b, miR-584-5p, miR-452-5p, and miR-1306-5p) is capable of classifying luminal and non-luminal breast cancers

BACKGROUND Identifying the molecular subtypes of breast cancer (BC) plays a crucial role in enhancing the efficacy of therapy. MiRNAs (miRs) with differential expressions in different subtypes of breast tumors can be considered as non-invasive biomarkers for diagnosing BC subtypes. OBJECTIVE We aimed to investigate the efficacy of miR-190b, miR-584-5p, miR-452-5p, and miR-1306-5p as novel potent diagnostic biomarkers in discriminating patients with luminal (ER+) and non-luminal (ER–) BCs. METHODS A group of miRs significantly associated with estrogen cell receptors (ER) in breast tumors were identified using feature selection methods analysis on miR-Seq datasets retrieved from TCGA and GSE68085. Four abovementioned miRs were selected as novel potential biomarkers, and their relative expression levels were assessed within adjacent non-tumor, ER+ and ER– tumor tissues by quantitative RT-PCR. Their impact on diagnosis was also evaluated by ROC curve analysis. RESULTS In ER+ BCs compared to ER– BCs, the expression of miR-190b was remarkably increased, while the expression of miR-584-5p, miR-452-5p, and miR-1306-5p were significantly decreased. This group could discriminate ER+ and ER– BCs at an AUC of 0.973. CONCLUSIONS According to our findings, these four miRs are promising biomarkers in discriminating BC subtypes. The candidate miRs in parallel with histologic diagnosis methods can be applied for identifying patients who are most likely responding to specific therapies based on ER status. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The research protocol for in vitro experiments on tissue samples was approved by the ethics committee of Ferdowsi University of Mashhad (code number: IR.UM.REC.1399.104). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.