Expression and function of the miR-143/145 cluster in vitro and in vivo in human breast cancer

PLoS One

Stig Manfred Dalen¹  Tonje Braaten²  Yury Kiselev²  Lill-Tove Busund³  Mona Irene Pedersen⁴  Line Moi⁵  Charles Johannessen⁵ 

[1] Department of Clinical Medicine, UiT—The Arctic University of Norway, Tromsø, Norway;Department of Clinical Pathology, University Hospital of North Norway, Tromsø, Norway;Department of Community Medicine, UiT—The Arctic University of Norway, Tromsø, Norway;Department of Life Sciences and Health, Oslo and Akershus University College of Applied Sciences, Oslo, Norway;Department of Medical Biology, UiT—The Arctic University of Norway, Tromsø, Norway

关键词: MicroRNAs;    Cell staining;    Breast tissue;    Microarrays;    Breast tumors;    Breast cancer;    Stromal cells;    Transfection;   

DOI  :  10.1371/journal.pone.0186658

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

MicroRNAs (miRNAs) are small non-coding RNAs that function as post-transcriptional regulators of gene expression and are dysregulated in cancer. Studies of miRNAs to explore their potential as diagnostic and prognostic markers are of great scientific interest. Here, we investigate the functional properties and expression of the miR-143/145 cluster in breast cancer (BC) in vitro and in vivo. The ER positive MCF7, the HER2 positive SK-BR-3, and the triple negative cell line MDA-MB-231 were used to assess cell proliferation and cell invasion. Expression of miRNA in 108 breast cancers in the Norwegian Women and Cancer Study and 44 benign tissue controls were analyzed by microarray and validated by RT-PCR. Further, in situ hybridization (ISH) was used to study the cellular and subcellular distribution of the miRNAs. In vitro, miR-143 promoted proliferation of MCF7 and MDA-MB-231 cells, whereas miR-145 and the cotransfection of both miRNAs inhibited proliferation in all three cell lines. The cells’ invasive capacity was reduced after transfection and cotransfection of the miRNAs. In line with the tumor suppressive functions in vitro, the expression of miR-143 and miR-145 was lower in malignant compared to benign breast tissue, and lower in the more aggressive tumors with higher tumor grade, loss of ER and the basal-like phenotype. ISH revealed miR-143 to be cytoplasmatic and predominantly expressed in luminal cells in benign tissue, whilst miR-145 was nuclear and with strong staining in myoepithelial cells. Both miRNAs were present in malignant epithelial cells and stromal fibroblasts in BC. This study demonstrates that miR-143 and -145 have functional properties and expression patterns typical for tumor suppressors, but the function is influenced by cellular factors such as cell type and miRNA cotransfection. Further, the nuclear functions of miR-145 should be explored for a more complete understanding of the complexity of miRNA regulation and function in BC.

【 授权许可】

CC BY