BRD4, a member of the bromodomain and extra-terminal domain (BET) protein family, plays a role in the organization of super-enhancers and transcriptional activation of oncogenes in cancer, and is recognized as a promising target for cancer therapy. microRNAs (miRNAs), endogenous small noncoding RNAs, cause mRNA degradation or inhibit protein translation of their target genes by binding to complementary sequences. miRNA mimics simultaneously targeting several tumor-promoting genes and BRD4 may be useful as therapeutic agents of tumor-suppressive miRNAs (TS-miRs) for cancer therapy. To investigate TS-miRs for the development of miRNA-based cancer therapeutics, we performed function-based screening in 10 cancer cell lines with a library containing 2,565 human miRNA mimics. Consequently, miR-1293, miR-876-3p, and miR-6571-5p were identified as TS-miRs targeting BRD4 in this screening. Notably, miR-1293 also suppressed DNA repair pathways by directly suppressing the DNA repair genes APEX1, RPA1, and POLD4. Concurrent suppression of BRD4 and these DNA repair genes synergistically inhibited tumor cell growth in vitro. Furthermore, administration of miR-1293 suppressed in vivo tumor growth in a xenograft mouse model. These results suggest that miR-1293 is a candidate for the development of miRNA-based cancer therapeutics.

JOURNAL：
Molecular Therapy

TITLE：
miR-1293, a candidate for miRNA-based cancer therapeutics, simultaneously targets BRD4 and the DNA repair pathway

DOI：
https://doi.org/10.1016/j.ymthe.2020.04.001

Yasuyuki Gen, Ph.D., Assistant Professor
Johji Inazawa, Ph.D., Professor
Department of Molecular Cytogenetics,
Medical Research Institute,
Tokyo Medical and Dental University(TMDU)
E-mail：johinaz.cgen (at) mri.tmd.ac.jp


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