The SWCNT is a novel nanomaterial that can deliver various types of drugs, such as proteins, small molecules, and nucleic acids, stably and efficiently with ideal tolerability and minimum toxicity in vitro1 and in vivo2. A functionalized SWCNT has great biocompatibility and water solubility, can be used as a shuttle for smaller molecules, and can carry them to penetrate the cell membrane3,4,5.
lncRNAs are a cluster of RNA (>200 nt) that are transcribed from the genome to mRNA but cannot be translated to proteins. Increasing evidence has shown that lncRNAs participate in the regulation of gene expression6 and are involved in the initiation and progression of most types of cancer, including MM7,8,9. MALAT1 is a nuclear-enriched noncoding transcript 2 (NEAT2) and a highly conserved lncRNA10. MALAT1 is initially recognized in metastatic non-small-cell lung cancer (NSCLC)11, but has been overexpressed in numerous tumors5,12,13; it is one of the most highly expressed lncRNAs and is correlated with a poor prognosis in MM8,14. The expression level of MALAT1 is significantly higher in fatal course extramedullary MM patients compared to those only diagnosed as MM15.
In a previous study, we have confirmed that anti-MALAT1 oligos robustly lead to DNA damage and apoptosis in MM16 by using gapmer DNA antisense oligonucleotides targeting MALAT1 (anti-MALAT1) in MM cells. The gapmer DNA is composed of antisense DNA and linked by 2'-OMe-RNAs, which could prompt MALAT1 cleavage by RNase H activity once bound17. The in vivo delivery efficiency of antisense oligos still limits its clinical usage.
To test the delivery effect of SWCNT for anti-MALAT1 gapmer oligos, the anti-MALAT1 gapmer DNA is conjugated to DSPE-PEG2000-amine functionalized SWCNT. The SWCNT-anti-MALAT1 is then injected intravenously into an MM disseminated mouse model; a striking inhibition is observed after four treatments.