RB loss contributes to aggressive tumor phenotypes in MYC-driven triple negative breast cancer

Erik S. Knudsen, A. Kathleen McClendon, Jorge Franco, Adam Ertel, Paolo Fortina, Agnieszka K. Witkiewicz

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

Triple negative breast cancer (TNBC) is characterized by multiple genetic events occurring in concert to drive pathogenic features of the disease. Here we interrogated the coordinate impact of p<sup>53</sup>, RB, and MYC in a genetic model of TNBC, in parallel with the analysis of clinical specimens. Primary mouse mammary epithelial cells (mMEC) with defined genetic features were used to delineate the combined action of RB and/or p<sup>53</sup> in the genesis of TNBC. In this context, the deletion of either RB or p<sup>53</sup> alone and in combination increased the proliferation of mMEC; however, the cells did not have the capacity to invade in matrigel. Gene expression profiling revealed that loss of each tumor suppressor has effects related to proliferation, but RB loss in particular leads to alterations in gene expression associated with the epithelial-to-mesenchymal transition. The overexpression of MYC in combination with p<sup>53</sup> loss or combined RB/p<sup>53</sup> loss drove rapid cell growth. While the effects of MYC overexpression had a dominant impact on gene expression, loss of RB further enhanced the deregulation of a gene expression signature associated with invasion. Specific RB loss lead to enhanced invasion in boyden chambers assays and gave rise to tumors with minimal epithelial characteristics relative to RB-proficient models. Therapeutic screening revealed that RB-deficient cells were particularly resistant to agents targeting PI3K and MEK pathway. Consistent with the aggressive behavior of the preclinical models of MYC overexpression and RB loss, human TNBC tumors that express high levels of MYC and are devoid of RB have a particularly poor outcome. Together these results underscore the potency of tumor suppressor pathways in specifying the biology of breast cancer. Further, they demonstrate that MYC overexpression in concert with RB can promote a particularly aggressive form of TNBC.

Original languageEnglish (US)
Pages (from-to)109-122
Number of pages14
JournalCell Cycle
Volume14
Issue number1
DOIs
StatePublished - Jan 1 2015

    Fingerprint

Keywords

  • Basal-like breast cancer
  • Biomarkers
  • Cell cycle
  • EMT
  • MYC
  • p53
  • RB tumor suppressor
  • Targeted therapy
  • Triple negative breast cancer

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology
  • Developmental Biology

Cite this