Molecular analysis of a multistep lung cancer model induced by chronic inflammation reveals epigenetic regulation of p16 and activation of the DNA damage response pathway

Neoplasia. 2007 Oct;9(10):840-52. doi: 10.1593/neo.07517.


The molecular hallmarks of inflammation-mediated lung carcinogenesis have not been fully clarified, mainly due to the scarcity of appropriate animal models. We have used a silica-induced multistep lung carcinogenesis model driven by chronic inflammation to study the evolution of molecular markers and genetic alterations. We analyzed markers of DNA damage response (DDR), proliferative stress, and telomeric stress: gamma-H2AX, p16, p53, and TERT. Lung cancer-related epigenetic and genetic alterations, including promoter hypermethylation status of p16(CDKN2A), APC, CDH13, Rassf1, and Nore1A, as well as mutations of Tp53, epidermal growth factor receptor, K-ras, N-ras, and c-H-ras, have been also studied. Our results showed DDR pathway activation in preneoplastic lesions, in association with inducible nitric oxide synthase and p53 induction. p16 was also induced in early tumorigenic progression and was inactivated in bronchiolar dysplasias and tumors. Remarkably, lack of mutations of Ras and epidermal growth factor receptor, and a very low frequency of Tp53 mutations suggest that they are not required for tumorigenesis in this model. In contrast, epigenetic alterations in p16(CDKN2A), CDH13, and APC, but not in Rassf1 and Nore1A, were clearly observed. These data suggest the existence of a specific molecular signature of inflammation-driven lung carcinogenesis that shares some, but not all, of the molecular landmarks of chemically induced lung cancer.

Keywords: DNA damage response; animal model; inflammation; lung cancer; preneoplastic lesions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Cadherins / genetics
  • Cadherins / metabolism
  • Chronic Disease
  • DNA Damage / genetics*
  • DNA Methylation
  • DNA Mutational Analysis
  • Epigenesis, Genetic*
  • Female
  • Genes, APC
  • Genes, erbB-1 / genetics
  • Genes, p16*
  • Genes, p53 / genetics
  • Genes, ras / genetics
  • Histones / genetics
  • Histones / metabolism
  • Immunohistochemistry
  • Inflammation / chemically induced
  • Inflammation / genetics*
  • Inflammation / pathology
  • Lung Neoplasms / chemically induced
  • Lung Neoplasms / genetics*
  • Lung Neoplasms / pathology
  • Mutation
  • Polymerase Chain Reaction
  • Precancerous Conditions / chemically induced
  • Precancerous Conditions / genetics*
  • Precancerous Conditions / pathology
  • Promoter Regions, Genetic
  • Rats
  • Rats, Inbred F344
  • Silicon Dioxide / toxicity
  • Telomerase / genetics
  • Telomerase / metabolism
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism


  • Cadherins
  • H-cadherin
  • Histones
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • Silicon Dioxide
  • Telomerase