The Super Enhancer-Driven Long Noncoding RNA PRKCQ-AS1 Promotes Neuroblastoma Tumorigenesis by Interacting With MSI2 Protein and Is Targetable by Small Molecule Compounds.

Tumorigenic drivers of MYCN gene nonamplified neuroblastoma remain largely uncharacterized. Long noncoding RNAs (lncRNAs) regulate tumorigenesis, however, there is little literature on therapeutic targeting of lncRNAs with small molecule compounds. Here PRKCQ-AS1 is identified as the lncRNA most overexpressed in MYCN nonamplified, compared with MYCN-amplified, neuroblastoma cell lines. PRKCQ-AS1 expression is controlled by super-enhancers, and PRKCQ-AS1 RNA bound to MSI2 protein. RNA immunoprecipitation and sequencing identified BMX mRNA as the transcript most significantly disrupted from binding to MSI2 protein, after PRKCQ-AS1 knockdown. PRKCQ-AS1 or MSI2 knockdown reduces, while its overexpression enhances, BMX mRNA stability and expression, ERK protein phosphorylation and MYCN nonamplified neuroblastoma cell proliferation. PRKCQ-AS1 knockdown significantly suppresses neuroblastoma progression in mice. In human neuroblastoma tissues, high levels of PRKCQ-AS1 and MSI2 expression correlate with poor patient outcomes, independent of current prognostic markers. AlphaScreen of a compound library identifies NSC617570 as an efficient inhibitor of PRKCQ-AS1 RNA and MSI2 protein interaction, and NSC617570 reduces BMX expression, ERK protein phosphorylation, neuroblastoma cell proliferation in vitro and tumor progression in mice. The study demonstrates that PRKCQ-AS1 RNA interacts with MSI2 protein to induce neuroblastoma tumorigenesis, and that targeting PRKCQ-AS1 and MSI2 interaction with small molecule compounds is an effective anticancer strategy.