Abstract P2-07-09: Integrative analysis of miRNA and mRNA expression in metastatic versus non-metastatic triple negative breast cancer
Authors: Shih AJ , Korsunsky I , Guttadauria B , Bhuiya T , Liew A , Khalili H , Gregersen PK , Lee AT 
Published: February 2018

Background: Triple Negative Breast Cancer (TNBC) is a subset of breast cancer that is difficult to treat clinically and is characterized by being estrogen receptor (ER) negative, progesterone receptor (PR) negative, and does not overexpress human epidermal growth factor receptor 2 (HER2). Patients with TNBC tend to have a worse prognosis than other breast cancer subtypes.

Methods: We obtained fifteen TNBC sample FFPE tissue blocks with corresponding plasma samples. All samples were from primary tumors; seven samples having metastasized, four samples that had not metastasized and four samples with unknown metastatic status. The total RNA was isolated from FFPE blocks using the RecoverAll Total Nucleic Acid Isolation Protocol. miRNA from plasma was isolated using Ambion's mirVANA kit. The plasma and tissue miRNAs were evaluated using the QuantStudio qPCR platform, capturing ˜750 miRNAs. The mRNA was processed using the TruSeq RNA Access kit and sequenced on the Illumina NextSeq platform. Analysis of the miRNA and mRNA individually was performed using limma and DESeq2 packages, respectively. Gene enrichment analysis of the mRNA expression was done using the GAGE package on KEGG pathways while the integrative analysis was done with sparse Canonical Correlation Analysis (sCCA) using the PMA pacakge.

Results: Analysis of plasma miRNA had four miRNAs with a significant difference in raw p-value (p &lt; 0.05) between metastatic and non-metastatic TNBC; miRNA 708, 483-3p, 518f, and 766; in the tissue there were fifteen miRNA with p &lt; 0.05, with one miR-872 still having significance after adjusting for multiple testing. mRNA had 33 genes being significant after multiple testing correction with several immune KEGG pathways being downregulated in metastatic samples (adjusted p &lt; 0.05). The integrative analysis revealed five microRNA (miR-216, miR-127, miR-370, miR-382, and miR-487b) and 312 gene modules enriched in integrin (Fisher p &lt; 10^-5) and extracellular matrix (Fisher p &lt; 10^-6) signaling.

Conclusions: One of the circulating plasma miRNAs, miR483-3p, has been found to promote tumorigenesis, while miR581f and miR766 have not been reported in cancer to date. Further investigation into these miRNA could provide a feasible biomarker. The downregulation of immune pathways observed within the metastatic TNBC subjects implies immune evasion is of particular importance for metastasis and a targeted immunotherapy may be a viable treatment option. The integrative analysis of the miRNA and mRNA showed an enrichment in pathways previously linked to increased proliferation and chemoresistance, with an increased signal compared to either miRNA or mRNA alone.

Citation Format: Shih AJ, Korsunsky I, Guttadauria B, Bhuiya T, Liew A, Khalili H, Gregersen PK, Lee AT. Integrative analysis of miRNA and mRNA expression in metastatic versus non-metastatic triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-07-09.