Tissue specificity of oncogenic BRAF targeted to lung and thyroid through a shared lineage factor.

Cells of origin in cancer determine tumor phenotypes, but whether lineage-defining transcription factors might influence tissue specificity of tumorigenesis among organs with similar developmental traits are unknown. We demonstrate here that tumor development and progression markedly differ in lung and thyroid targeted by mutation in mice heterozygous for . In absence of tamoxifen, non-induced mutants developed multiple full-blown lung adenocarcinomas with a latency of 1-3 months whereas thyroid tumors were rare and constrained, although minute activation documented by variant allele sequencing was similar in both tissues. Induced oncogene activation accelerated neoplastic growth only in the lungs. By contrast, NKX2-1 progenitor cells were equally responsive to constitutive expression of mutant Braf during lung and thyroid development. Both lung and thyroid cells transiently downregulated NKX2-1 in early tumor stages. These results indicate that BRAF-induced tumorigenesis obey organ-specific traits that might be differentially modified by a shared lineage factor.