MicroRNA-375 Suppresses the Growth and Invasion of Fibrolamellar Carcinoma.
BACKGROUND & AIMS
Fibrolamellar carcinoma (FLC) is a rare liver cancer that primarily affects adolescents and young adults. It is characterized by a heterozygous approximately 400-kb deletion on chromosome 19 that results in a unique fusion between DnaJ heat shock protein family member B1 (DNAJB1) and the alpha catalytic subunit of protein kinase A (PRKACA). The role of microRNAs (miRNAs) in FLC remains unclear. We identified dysregulated miRNAs in FLC and investigated whether dysregulation of 1 key miRNA contributes to FLC pathogenesis.


METHODS
We analyzed small RNA sequencing (smRNA-seq) data from The Cancer Genome Atlas to identify dysregulated miRNAs in primary FLC tumors and validated the findings in 3 independent FLC cohorts. smRNA-seq also was performed on a FLC patient-derived xenograft model as well as purified cell populations of the liver to determine whether key miRNA changes were tumor cell-intrinsic. We then used clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (Cas9) technology and transposon-mediated gene transfer in mice to determine if the presence of DNAJB1-PRKACA is sufficient to suppress miR-375 expression. Finally, we established a new FLC cell line and performed colony formation and scratch wound assays to determine the functional consequences of miR-375 overexpression.


RESULTS
We identified miR-375 as the most dysregulated miRNA in primary FLC tumors (27-fold down-regulation; P = .009). miR-375 expression also was decreased significantly in a FLC patient-derived xenograft model compared to 4 different cell populations of the liver. Introduction of DNAJB1-PRKACA by clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 engineering and transposon-mediated somatic gene transfer in mice was sufficient to induce significant loss of miR-375 expression (P < .05). Overexpression of miR-375 in FLC cells inhibited Hippo signaling pathway proteins, including yes-associated protein 1 and connective tissue growth factor, and suppressed cell proliferation and migration (P < .05).


CONCLUSIONS
We identified miR-375 as the most down-regulated miRNA in FLC tumors and showed that overexpression of miR-375 mitigated tumor cell growth and invasive potential. These findings open a potentially new molecular therapeutic approach. Further studies are necessary to determine how DNAJB1-PRKACA suppresses miR-375 expression and whether miR-375 has additional important targets in this tumor. Transcript profiling: GEO accession numbers: GSE114974 and GSE125602.
['Dinh|Timothy A|TA|', 'Jewell|Mark L|ML|', 'Kanke|Matt|M|', 'Francisco|Adam|A|', 'Sritharan|Ramja|R|', 'Turnham|Rigney E|RE|', 'Lee|Seona|S|', 'Kastenhuber|Edward R|ER|', 'Wauthier|Eliane|E|', 'Guy|Cynthia D|CD|', 'Yeung|Raymond S|RS|', 'Lowe|Scott W|SW|', 'Reid|Lola M|LM|', 'Scott|John D|JD|', 'Diehl|Anna M|AM|', 'Sethupathy|Praveen|P|']
D000818:Animals D006528:Carcinoma, Hepatocellular D049109:Cell Proliferation D054751:Cyclic AMP-Dependent Protein Kinase Catalytic Subunits D005260:Female D015972:Gene Expression Regulation, Neoplastic D050956:HSP40 Heat-Shock Proteins D006801:Humans D008099:Liver D008113:Liver Neoplasms D008810:Mice, Inbred C57BL D035683:MicroRNAs D009361:Neoplasm Invasiveness D015398:Signal Transduction D023041:Xenograft Model Antitumor Assays
Fibrolamellar Carcinoma miRNA Cancer Genomics Pediatric Cancer