Abstract
Most cancers are diagnosed in people over 60 years of age, but little is known about how age impacts tumorigenesis. While aging is accompanied by mutation accumulation (widely understood to contribute to cancer risk) it is associated with numerous other cellular and molecular changes likely to impact tumorigenesis. Moreover, cancer incidence decreases in the oldest part of the population, suggesting that very old age may reduce carcinogenesis. Here we show that aging represses oncogenic KRAS-driven tumor initiation and growth in genetically engineered mouse models of human lung cancer. Moreover, aging dampens the impact of inactivating many tumor suppressor genes with the impact of inactivating PTEN, a negative regulator of the PI3K-AKT pathway, weakened disproportionately. Single-cell transcriptomic analysis revealed that neoplastic cells in aged mice retain age-related transcriptomic changes, showing that the impact of age persists through oncogenic transformation. Furthermore, the consequences of PTEN inactivation were strikingly age-dependent, with PTEN deficiency reducing signatures of aging in cancer cells and the tumor microenvironment. Our findings underscore the interconnectedness of the pathways involved in aging and tumorigenesis and document tumor-suppressive effects of aging that may contribute to the deceleration in cancer incidence with age.