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

ABSTRACT: Development of targeted therapies for triple-negative breast cancer (TNBC) has failed at least in part because of the heterogeneity of these poor prognosis cancers. To identify common dependencies of basal-like TNBCs, we performed a targeted siRNA lethality screen in 7 human breast cancer cell lines focusing on 154 previously identified dependency genes of one basal-A TNBC line. Thirty genes were shared basal-A TNBC dependencies. Genes for proteins involved in RNA splicing, in particular those associated with the U4/U6.U5 tri-snRNP complex (e.g. PRPF8, PRPF38A), were prominent shared dependencies. Spliceosome genes were commonly up-regulated in primary basal-like TNBCs. Knockdown of PRPF8 or PRPF38A led to widespread intronic retention, expression of immune system genes and aberrant splicing of transcripts involved in protein translation, proteasome function, mitosis and apoptosis, including the TNBC dependency gene MCL1. These transcripts were susceptible to inhibition of RNA splicing more generally, since they were similarly affected by the RNA splicing inhibitor drug E7107. In particular, E7107 caused splicing of MCL1 to its pro-apoptotic splicing variant in multiple cell lines, killed MCL1-dependent basal-A cells in vitro, and suppressed the growth of 2 basal-A cell-lines and 1 of 2 patient-derived basal-like TNBC xenografts in vivo. Thus, TNBCs critically rely on RNA splicing and could be susceptible to RNA splicing inhibitors.

ORGANISM(S): Homo sapiens

PROVIDER: GSE90519 | GEO | 2018/01/01

SECONDARY ACCESSION(S): PRJNA354957

REPOSITORIES: GEO