Enhanced inflammation and attenuated tumor suppressor pathways are associated with oncogene-induced lung tumors in aged mice

Aging Cell. 2018 Feb;17(1):e12691. doi: 10.1111/acel.12691. Epub 2017 Oct 18.

Abstract

Aging is often accompanied by a dramatic increase in cancer susceptibility. To gain insights into how aging affects tumor susceptibility, we generated a conditional mouse model in which oncogenic KrasG12D was activated specifically in lungs of young (3-5 months) and old (19-24 months) mice. Activation of KrasG12D in old mice resulted in shorter survival and development of higher-grade lung tumors. Six weeks after KrasG12D activation, old lung tissues contained higher numbers of adenomas than their young tissue counterparts. Lung tumors in old mice displayed higher proliferation rates, as well as attenuated DNA damage and p53 tumor suppressor responses. Gene expression comparison of lung tumors from young and old mice revealed upregulation of extracellular matrix-related genes in young tumors, indicative of a robust cancer-associated fibroblast response. In old tumors, numerous inflammation-related genes such as Ccl7, IL-1β, Cxcr6, and IL-15ra were consistently upregulated. Increased numbers of immune cells were localized around the periphery of lung adenomas from old mice. Our experiments indicate that more aggressive lung tumor formation in older KrasG12D mice may be in part the result of subdued tumor suppressor and DNA damage responses, an enhanced inflammatory milieu, and a more accommodating tissue microenvironment.

Keywords: Kras; aging; cancer; inflammation; p53; tumor microenvironment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / physiology*
  • Animals
  • Cell Proliferation / genetics*
  • Cell Transformation, Neoplastic / genetics*
  • Disease Models, Animal
  • Genes, ras / genetics
  • Inflammation / genetics*
  • Lung Neoplasms / genetics*
  • Mice
  • Mutation / genetics
  • Signal Transduction / genetics