期刊
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
卷 23, 期 9, 页码 -出版社
MDPI
DOI: 10.3390/ijms23095131
关键词
microRNA449a; triple negative breast cancer; DNA repair; chromosomal instability; chromatid separation
资金
- Danish National Research Foundation [DNRF115]
This study identified a previously unknown role of microRNA-449a in chromosomal instability (CIN), showing its potential as a therapeutic target for TNBC. The overexpression of microRNA-449a induced apoptosis, reduced cell proliferation, and downregulated genes involved in homology directed repair (HDR). The study also identified a new target gene, EME1, and revealed two mechanisms through which microRNA-449a increases CIN and induces apoptosis in TNBC cell lines.
Chromosomal instability (CIN) can be a driver of tumorigenesis but is also a promising therapeutic target for cancer associated with poor prognosis such as triple negative breast cancer (TNBC). The treatment of TNBC cells with defects in DNA repair genes with poly(ADP-ribose) polymerase inhibitor (PARPi) massively increases CIN, resulting in apoptosis. Here, we identified a previously unknown role of microRNA-449a in CIN. The transfection of TNBC cell lines HCC38, HCC1937 and HCC1395 with microRNA-449a mimics led to induced apoptosis, reduced cell proliferation, and reduced expression of genes in homology directed repair (HDR) in microarray analyses. EME1 was identified as a new target gene by immunoprecipitation and luciferase assays. The reduced expression of EME1 led to an increased frequency of ultrafine bridges, 53BP1 foci, and micronuclei. The induced expression of microRNA-449a elevated CIN beyond tolerable levels and induced apoptosis in TNBC cell lines by two different mechanisms: (I) promoting chromatid mis-segregation by targeting endonuclease EME1 and (II) inhibiting HDR by downregulating key players of the HDR network such as E2F3, BIRC5, BRCA2 and RAD51. The ectopic expression of microRNA-449a enhanced the toxic effect of PARPi in cells with pathogenic germline BRCA1 variants. The newly identified role makes microRNA-449a an interesting therapeutic target for TNBC.
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