Basal-A Triple-Negative Breast Cancer Cells Selectively Rely on RNA Splicing for Survival

Mol Cancer Ther. 2017 Dec;16(12):2849-2861. doi: 10.1158/1535-7163.MCT-17-0461. Epub 2017 Sep 6.

Abstract

Prognosis of triple-negative breast cancer (TNBC) remains poor. To identify shared and selective vulnerabilities of basal-like TNBC, the most common TNBC subtype, a directed siRNA lethality screen was performed in 7 human breast cancer cell lines, focusing on 154 previously identified dependency genes of 1 TNBC line. Thirty common dependency genes were identified, including multiple proteasome and RNA splicing genes, especially those associated with the U4/U6.U5 tri-snRNP complex (e.g., PRPF8, PRPF38A). PRPF8 or PRPF38A knockdown or the splicing modulator E7107 led to widespread intronic retention and altered splicing of transcripts involved in multiple basal-like TNBC dependencies, including protein homeostasis, mitosis, and apoptosis. E7107 treatment suppressed the growth of basal-A TNBC cell line and patient-derived basal-like TNBC xenografts at a well-tolerated dose. The antitumor response was enhanced by adding the proteasome inhibitor bortezomib. Thus, inhibiting both splicing and the proteasome might be an effective approach for treating basal-like TNBC. Mol Cancer Ther; 16(12); 2849-61. ©2017 AACR.

MeSH terms

  • Cell Proliferation
  • Female
  • Humans
  • Prognosis
  • RNA Splicing / genetics*
  • Survival Analysis
  • Triple Negative Breast Neoplasms / genetics*
  • Triple Negative Breast Neoplasms / mortality