Silencing of the Long Noncoding RNA MYCNOS1 Suppresses Activity of MYCN-Amplified Retinoblastoma Without RB1 Mutation

MYCNOS (MYCN opposite strand) is co-amplified with MYCN in pediatric cancers including retinoblastoma. MYCNOS encodes several RNA variants whose functions have not been elucidated in retinoblastoma. Here, we attempted to decipher the role of MYCNOS variant 1 (MYCNOS1) on the activity of MYCN-amplified retinoblastoma. We observed that MYCNOS1 supports progression of retinoblastoma. Inhibition of MYCNOS1 expression may be needed to suppress MYCN activity when treating MYCN-amplified cancers without RB1 mutation. Overall design: Tumor tissue was dissociated, and the resulting cells were cultured in the growth medium developed previously in Saengwimol et al. "A three-dimensional organoid model recapitulates tumorigenic aspects and drug responses of advanced human retinoblastoma". Functional study of MYCNOS1 expression was conducted in patient-derived tumor cells and in retinoblastoma cell line via short hairpin RNA-mediated gene silencing.