Objective: Pure mucinous breast carcinoma (PMBC) is an uncommon histological type of breast cancer characterized by a large amount of mucin production. MicroRNA (miRNA) is a large class of small noncoding RNA of about 22 nt involved in the regulation of various biological processes. This study aims to identify the miRNA expression profile in PMBC. Methods: MiRNA expression profiles in 11 PMBCs were analyzed by miRNA-microarray and real-time polymerase chain reaction (PCR). Thirty-one PMBCs and 27 invasive ductal carcinoma of no special types (IDC-NSTs) were assessed by immunohistochemistry using antibodies against ER, PR-progesterone receptor, HER2, Ki-67, Bcl-2, p53, PCNA, and CK5 and 6. Results: We analyzed the miRNA expression in 11 PMBCs and corresponding normal tissues using miRNA-microarray and real-time PCR, and found that miR-143 and miR-224-5p were significantly downregulated in mucinous carcinoma tissue. Compared with IDC-NSTs, PMBC showed a significantly higher ER positive rate, lower HER-2 positive rate, and lower cell proliferation rates. Conclusions: To our knowledge, this is the first study to demonstrate the miRNA expression profile of PMBC, and our findings may lead to further understanding of this type of breast cancer.
