Minor intron splicing is critical for survival of lethal prostate cancer

Mol Cell. 2023 Jun 15;83(12):1983-2002.e11. doi: 10.1016/j.molcel.2023.05.017. Epub 2023 Jun 8.

Abstract

The evolutionarily conserved minor spliceosome (MiS) is required for protein expression of ∼714 minor intron-containing genes (MIGs) crucial for cell-cycle regulation, DNA repair, and MAP-kinase signaling. We explored the role of MIGs and MiS in cancer, taking prostate cancer (PCa) as an exemplar. Both androgen receptor signaling and elevated levels of U6atac, a MiS small nuclear RNA, regulate MiS activity, which is highest in advanced metastatic PCa. siU6atac-mediated MiS inhibition in PCa in vitro model systems resulted in aberrant minor intron splicing leading to cell-cycle G1 arrest. Small interfering RNA knocking down U6atac was ∼50% more efficient in lowering tumor burden in models of advanced therapy-resistant PCa compared with standard antiandrogen therapy. In lethal PCa, siU6atac disrupted the splicing of a crucial lineage dependency factor, the RE1-silencing factor (REST). Taken together, we have nominated MiS as a vulnerability for lethal PCa and potentially other cancers.

Keywords: CRPC; REST; U6atac siRNA; androgen receptor; castration-resistant prostate cancer; lineage plasticity; minor intron splicing; minor spliceosome; neuroendocrine prostate cancer; prostate cancer; small-cell prostate cancer; snRNAs; splicing; therapeutics; therapy resistance.

MeSH terms

  • Cell Line, Tumor
  • Humans
  • Introns / genetics
  • Male
  • Prostatic Neoplasms* / metabolism
  • Prostatic Neoplasms, Castration-Resistant* / genetics
  • RNA Splicing / genetics
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism
  • Signal Transduction
  • Spliceosomes / metabolism

Substances

  • Receptors, Androgen