TP53, CDKN2A/P16, and NFE2L2/NRF2 regulate the incidence of pure- and combined-small cell lung cancer in mice

Studies have shown that Nrf2(E79Q/+) is one of the most common mutations found in human tumors. To elucidate how this genetic change contributes to lung cancer, we compared lung tumor development in a genetically-engineered mouse model (GEMM) with dual Trp53/p16 loss, the most common mutations found in human lung tumors, in the presence or absence of Nrf2(E79Q/+). Trp53/p16-deficient mice developed combined-small cell lung cancer (C-SCLC), a mixture of pure-SCLC (P-SCLC) and large cell neuroendocrine carcinoma. Mice possessing the LSL-Nrf2(E79Q) mutation showed no difference in the incidence or latency of C-SCLC compared with Nrf2(+/+) mice. However, these tumors did not express NRF2 despite Cre-induced recombination of the LSL-Nrf2(E79Q) allele. Trp53/p16-deficient mice also developed P-SCLC, where activation of the NRF2(E79Q) mutation associated with a higher incidence of this tumor type. All C-SCLCs and P-SCLCs were positive for NE-markers, NKX1-2 (a lung cancer marker) and negative for P63 (a squamous cell marker), while only P-SCLC expressed NRF2 by immunohistochemistry. Analysis of a consensus NRF2 pathway signature in human NE+-lung tumors showed variable activation of NRF2 signaling. Our study characterizes the first GEMM that develops C-SCLC, a poorly-studied human cancer and implicates a role for NRF2 activation in SCLC development.

Automated summary

This study demonstrates the prevalence of Nrf2 (E79Q/+) mutation in human tumors, and suggests a role for NRF2 activation in the development of small cell lung cancer (SCLC).