Coherence between Cellular Responses and in Vitro Splicing Inhibition for the Anti-tumor Drug Pladienolide B and Its Analogs

Abstract

Background: Pladienolide B is a complex natural product that potently inhibits pre-mRNA splicing. Results: The same molecular features of pladienolide B are required for the drug's effects on cell growth, morphology, and splicing. Conclusion: Simplified synthesis and modification of active pladienolide B is possible. Significance: Pladienolide B analogs can be used to study the relationship between splicing and cancer cell function.

Interchangeable SF3B1 inhibitors interfere with pre-mRNA splicing at multiple stages

“…When SF3B1 is depleted or targeted by inhibitors, in vitro spliceosome assembly halts early at the point in which U2 snRNP recognizes a sequence in introns called the branch point (Brosi et al 1993;Roybal and Jurica 2010;Corrionero et al 2011;Folco et al 2011;Effenberger et al 2014). Yet there are hints that SF3B1 may function at multiple stages because the stability of its association with the spliceosome appears to be regulated (Coltri et al 2010;Lardelli et al 2010;Ilagan et al 2013).…”

“…Structure-activity relationship (SAR) data for the three compounds and related molecules have been steadily emerging (Sakai et al 2002;Mizui et al 2004;Lagisetti et al 2008Lagisetti et al , 2013Lagisetti et al , 2014Albert et al 2009;Fan et al 2011;Gundluru et al 2011;Muller et al 2011;Villa et al 2012Villa et al , 2013Gao et al 2013;Ghosh and Chen 2013;Arai et al 2014;Effenberger et al 2014;Ghosh et al 2014a,b,c;He et al 2014). SSA (1), which is similar to FR901464 (Nakajima et al 1996b), meayamycin (Albert et al 2009), thailanstatins (Liu et al 2013), and sudemycins (Fan et al 2011), differs in structure relative to the other two compounds.…”

“…In cells, treatment with SF3B1 inhibitors leads to changes in alternative splicing of genes involved in apoptosis and the cell cycle, among others (Kaida et al 2007;Kotake et al 2007;Lagisetti et al 2009;Corrionero et al 2011;Hasegawa et al 2011;Convertini et al 2014;Effenberger et al 2014). Microarray analysis of 2000 splicing events from nearly 500 genes suggested that SSA affects alternative splicing of introns with weak branch points (Corrionero et al 2011).…”

The Natural Product N-Palmitoyl-l-leucine Selectively Inhibits Late Assembly of Human Spliceosomes

“…SAR analysis revealed strong parallels between in vitro and cell activity, with acyl tail length having the most impact. The cytological profile produced by N-palmitoyl-L-leucine is distinct from that of the well-characterized effects shared by the well-known splicing inhibitors spliceostatin A and pladienolide B (21), which raises the possibility we are observing a new splicing phenotype. Notably, those compounds target an early stage of spliceosome assembly, while N-palmitoyl-L-leucine interferes with spliceosome activity at a much later stage.…”

“…Although our in vitro assays do not indicate substrate specificity, the situation in cells is much more complex with alternative splicing. Indeed, in cells, only a few splicing events appear to be sensitive to the early splicing inhibitors SSA and pladienolide B (4,21). Still, as a whole, the cytological profiling data enforce that N-palmitoyl-L-leucine has a clear link to splicing inhibition with a sharply defined SAR both in vitro and in cells.…”