A thermally targeted peptide inhibitor of symmetrical dimethylation inhibits cancer-cell proliferation

Targeting splicing machinery components is an underdeveloped strategy for cancer therapy. Uridine-rich small nuclear ribonucleoproteins (UsnRNPs) are essential spliceosome components that recognize splice sites in newly transcribed RNA. The major spliceosomal snRNPs are comprised of UsnRNA bound by a ring of Sm proteins. The survival of motor neuron (SMN) complex provides specificity for binding of Sm proteins to UsnRNAs. Three of the seven proteins that comprise the Sm core possess post-translationally modified C-terminal symmetric dimethylarginine (sDMA) residues which promote binding of these proteins to SMN. Here we describe a peptide inhibitor of sDMA that is capable of interfering with SMN/SmB interaction. The inhibitory peptide was attached to elastin-like polypeptide, a thermally responsive macromolecular carrier, in order to increase its stability and allow enhancement of its cellular uptake by thermal targeting. The fusion polypeptide inhibited the interaction of SMN/SmB, inhibited proliferation, and induced apoptosis in HeLa cells.