CRISPRi Screen Identifies a Novel Growth Suppressor lncRNA, INSTAR , in Human Monocytes

Acute myeloid leukemia (AML) is a heterogeneous disease that arises from dysregulated myeloid proliferation. We performed a high-throughput CRISPR interference (CRISPRi) screen in the THP-1 monocytic cancer cell line to identify long noncoding RNAs (lncRNAs) that play a role in contributing to cell proliferation. Our screen identified INSTAR (Intergenic Nuclear Suppressor lncRNA Targeting Adjacent Regulator SFMBT2 ) as a top candidate. RNA-seq on INSTAR deficient THP-1 cells revealed transcriptional changes in genes involved in cell proliferation as well as other cellular processes. Loss of INSTAR selectively reduced expression of its neighboring gene, SFMBT2 . Functional assays confirmed that both genes suppress cell growth, revealing a cis-regulatory mechanism in which INSTAR regulates SFMBT2 expression to control monocyte proliferation. Here, we leverage high-throughput screening to rapidly pinpoint functional lncRNAs providing novel insights into a key regulatory locus consisting of INSTAR and SFMBT2 which could be critical for better understanding dysregulation contributing to acute myeloid leukemia.