Inflammatory breast cancer is the most aggressive form of breast cancer. Identifying new biomarkers to
be used as therapeutic targets is in urgent need. Messenger RNA expression profiling studies have indicated
that inflammatory breast cancer is a transcriptionally heterogeneous disease, and specific molecular
targets for inflammatory breast cancer have not been well established. We performed microRNA expression
profiling in inflammatory breast cancer in comparison with locally advanced noninflammatory breast cancer in
this study. Although many microRNAs were differentially expressed between normal breast tissue and tumor
tissue, most of them did not show differential expression between inflammatory and noninflammatory tumor
samples. However, by microarray analysis, quantitative reverse transcription PCR, and in situ hybridization, we
showed that microRNA-205 expression was decreased not only in tumor compared with normal breast tissue, but
also in inflammatory breast cancer compared with noninflammatory breast cancer. Lower expression of
microRNA-205 correlated with worse distant metastasis-free survival and overall survival in our cohort.
A small-scale immunohistochemistry analysis showed coexistence of decreased microRNA-205 expression and
decreased E-cadherin expression in some ductal tumors. MicroRNA-205 may serve as a therapeutic target in
advanced breast cancer including inflammatory breast cancer.

Modern Pathology (2016) 29, 330–346; doi:10.1038/modpathol.2016.38; published online 26 February 2016
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