title: Recent trends in microRNA research into breast cancer with particular focus on the associations between microRNAs and intrinsic subtypes.
abstract: MicroRNAs (miRNAs) are short non-coding RNAs that regulate the function of target genes at the post-transcriptional phase. miRNAs are considered to have roles in the development, progression and metastasis of cancer. Recent studies have indicated that particular miRNA signatures are correlated with tumor aggressiveness, response to drug therapy and patient outcome in breast cancer. On the other hand, in routine clinical practice, the treatment regimens for breast cancer are determined based on the intrinsic subtype of the primary tumor. Previous studies have shown that miRNA expression profiles of each intrinsic subtypes of breast cancer differ. In hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer, miRNA expressions are found to be correlated with endocrine therapy resistance, progesterone receptor expression and heat shock protein activity. Some miRNAs are associated with resistance to HER2-targeted therapy and HER3 expression in HER2-positive breast cancer. In triple-negative breast cancer, miRNA expressions are found to be associated with BRCA mutations, immune system, epithelial-mesenchymal transition, cancer stem cell properties and androgen receptor expression. As it has been clarified that the expression levels and functions of miRNA differ among the various subtypes of breast cancer, and it is necessary to take account of the characteristics of each breast cancer subtype during research into the roles of miRNA in breast cancer. In addition, the discovery of the roles played by miRNAs in breast cancer might provide new opportunities for the development of novel strategies for diagnosing and treating breast cancer.
authors.affiliation: Division of Breast Surgery, Saitama Cancer Center, Saitama, Japan.|Department of Thoracic and Visceral Organ Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Sasagu
authors.initials: S
authors.lastname: Kurozumi
authors.affiliation: Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Department of Pathology, Saitama Cancer Center, Saitama, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kurosumi
authors.affiliation: Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Ohira
authors.affiliation: Division of Breast Surgery, Saitama Cancer Center, Saitama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsumoto
authors.affiliation: Department of Thoracic and Visceral Organ Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Horiguchi
mesh_terms: D019313:BRCA1 Protein / Q000235:genetics; D001943:Breast Neoplasms / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D009154:Mutation; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
chemical_list: D019313:BRCA1 Protein; D035683:MicroRNAs; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone