Comparative microRNA profiling of sporadic and BRCA1 associated basal-like breast cancers

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Background

While a number of studies have examined miRNA profiles across the molecular subtypes of breast cancer, it is unclear whether BRCA1 basal-like cancers have a specific miRNA profile. This study aims to compare grade independent miRNA expression in luminal cancers, sporadic and BRCA1 basal-type breast cancers. It also aims to ascertain an immunohistochemical profile regulated by BRCA1 specific miRNAs for potential diagnostic use.

Conclusion

In summary, our study demonstrates basal-like cancers have a grade independent miRNA expression profile. Furthermore miRNA driven differences in the expression of proteins by BRCA1 vs. sporadic basal cancers may be detected via immunohistochemical staining of paraffin embedded tissue. These findings may have important diagnostic implications, as immunohistochemical assessment of basal cancers, in addition to the patient’s family and clinical history, may potentially identify patients who may benefit from BRCA1 gene testing. Lastly, there is evidence to suggest BRCA1 deficient cancers may be sensitive to PARP inhibitors [47]. Hence stratification of basal-like cancers, based on the “BRCA1-ness” of their miRNA signature, generated from archival FFPE tissue, may be highly relevant to clinical trials investigating targeted therapies, such as PARP inhibitors [48]. Validation of these findings in larger patient cohorts, however, will be required to assess the diagnostic utility of such an approach.