Abstract
Oncogene-induced senescence (OIS) is proposed as a cellular defense mechanism that restrains malignant progression of oncogene-expressing, initiated tumor cells. Consistent with this, expression of BRAFV600E in the mouse lung epithelium elicits benign tumors that fail to progress to cancer due to an apparent senescence-like proliferative arrest. Here we demonstrate that nuclear β-catenin → c-MYC signaling is essential for early stage proliferation of BRAFV600E-induced lung tumors and is inactivated in the subsequent senescence-like state. Furthermore, either β-catenin silencing or pharmacological blockade of Porcupine, an acyl-transferase essential for WNT ligand secretion and activity, significantly inhibited BRAFV600E-initiated lung tumorigenesis. Conversely, sustained activity of β-catenin or c-MYC significantly enhanced BRAFV600E-induced lung tumorigenesis and rescued the anti-tumor effects of Porcupine blockade. These data indicate that early stage BRAFV600E-induced lung tumors are WNT-dependent and suggest that inactivation of WNT → β-catenin → c-MYC signaling is a trigger for the senescence-like proliferative arrest that constrains the expansion and malignant progression of BRAFV600E-initiated lung tumors. Moreover, these data further suggest that the trigger for OIS in initiated BRAFV600E-expressing lung tumor cells is not simply a surfeit of signals from oncogenic BRAF but an insufficiency of WNT → β-catenin → c-MYC signaling. These data have implications for understanding how genetic abnormalities cooperate to initiate and promote lung carcinogenesis.
Original language | English (US) |
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Pages (from-to) | 561-575 |
Number of pages | 15 |
Journal | Genes and Development |
Volume | 28 |
Issue number | 6 |
DOIs | |
State | Published - Mar 15 2014 |
Keywords
- BRAF
- Non-small-cell lung cancer
- c-MYC
- β-catenin
ASJC Scopus subject areas
- General Medicine