An unbiased lncRNAs dropout CRISPR-Cas9 screen reveals RP11-350G8.5 as a potential therapeutic target for Multiple Myeloma

Multiple Myeloma (MM) is an incurable malignancy characterised by alterations of coding and non-coding genes that promote tumour growth and drug resistance. Despite the crucial role of long non-coding-RNAs (lncRNAs) in myeloma genesis is established, the functional role of the non-coding RNAome in MM remains largely unknown. We performed an unbiased CRISPR-Cas9 recessive screen targeting 671 lncRNAs in MM cell lines unvealing and prioritising a list of novel onco-lncRNAs essential for MM cell fitness and associated with high expression and poor prognosis in MM patients. Among them, RP11-350G8.5 emerged as the most promising vulnerability for MM cells, irrespective of their resistance to the standard-of-care bortezomib. We i) validated the oncogenic role of RP11-350G8.5 in vitro and in vivo; ii) characterised its function in relation to the unfolded protein stress response and induction of immunogenic cell death, and iii) shed light on its sub-cellular localisation, structural and chemical predictions of RNA-G-quadruplex-forming regions to pave the way to the development of novel therapeutics. Overall design: To reveal the molecular changes induced by RP11-350G8.5 KO in MM cells resistant to bortezomib (ABZB), we profiled the cell line, 7 days post transduction with SCRAMBLE or RP11-350G8.5 KO CRISPR-Cas9 vectors, via RNA-sequencing from two independent biological replicates.