Differential Distribution of microRNAs in Breast Cancer Grouped by Clinicopathological Subtypes

Background: microRNAs (miRNAs) that regulate proliferation, invasion and metastasis are considered to bethe principal molecular basis of tumor heterogeneity. Breast cancer is not a homogeneous tissue. Thus, it is veryimportant to perform microarray-based miRNA screening of tumors at different sites.
Methods: Breast tissuesamples from the centers and edges of tumors of 30 patients were classified into 5 clinicopathological subtypes.In each group, 6 specimens were examined by microRNA array. All differential miRNAs were analyzed betweenthe edges and centers of the tumors.
Results: Seventeen kinds of miRNAs were heterogeneously distributedin the tumors from different clinicopathological subtypes that included 1 kind of miRNA in Luminal A andLuminal B Her2+ subtypes, 4 kinds in Luminal A and Her2 overexpression subtypes, 6 kinds in Luminal BKi67+ and Luminal B Her2+ subtypes, 2 kinds between Luminal B Ki67+ and triple-negative breast cancer(TNBC) subtypes, 2 kinds between Luminal B Her2+ and TNBC subtypes, and 2 kinds between Luminal BKi67+, Luminal B Her2+, and TNBC subtypes. Twenty kinds of miRNAs were homogenously distributed in thetumors from different clinicopathological subtypes that included 6 kinds of miRNAs in Luminal B Ki67+ andLuminal B Her2+ subtypes, 1 kind in Luminal B Ki67+ and Her2 overexpression subtypes, 10 kinds betweenLuminal B Ki67+ and TNBC subtypes, 2 kinds in Luminal B Her2+ and TNBC subtypes, and 1 kind betweenLuminal B Ki67+, Luminal B Her2+, and TNBC subtypes.
Conclusions: A total of 37 miRNAs were significantlydistributed in tumors from the centers to edges, and in all clinicopathological subtypes.