Amplification Of Mouse Chromosome 4 In Chemically Induced And Invasive Mouse Lung Adenocarcinoma

Lung cancer is the leading cause of cancer death in the United States and is ranked second only to bladder cancer in proportion of cases due to past occupational exposures. Though the genetic changes associated with lung cancer are not well understood, the pattern of mutations observed in lung adenocarcinoma from tobacco exposed patients is distinct from that of lung adenocarcinoma from unexposed patients. We used Spectral Karyotyping (SKY), mapping with fluorescently labeled genomic clones (FISH), comparative genomic hybridization (CGH), expression array, real time polymerase chain reaction and Western blot to analyze 15 primary adenocarcinoma and 9 pairs of high and low invasive cell cultures to detect molecular changes. The medial portion of chromosome 4 was deleted in 67% of all of the cell strains. Duplication of the proximal region of chromosome 4 occurred in 22% of the spontaneously-occurring high-invasive cells strains and 83% of the chemically-induced high-invasive cell cultures. Mouse chromosome 1 and 15 were amplified in 90% of the high-invasive cell strains. FISH mapping further narrowed the region of deletion of chromosome 4 to 39.6 centimorgans (cM) and the region of duplication to 10-35 cM. Expression array and real time PCR analysis demonstrated increased expression of the cell cycle inhibitory factor p16 and the apoptotic factor Cathepsin D in all of the tumor cell strains. The expression of cyclooxygenase 2 (COX-2), Kruppel like factor-4 (KLF4), Cyclin E and c-myc was significantly higher in the high-invasive cells strains compared to the low-invasive cell strains. Western blotting showed increased Cox-2, Cyclin E, KLF4 and c-myc proteins and decreased expression of Cathepsin D. In addition, the KLF4 protein was higher in the chemically-induced cell strains compared to the spontaneously-occurring cell strains while COX-2 was higher in the spontaneously-occurring cell strains. The KLF4 protein was identified in the tumor cell strains at the expected size of 55 KD as well as a smaller 45 KD form. Coordinated expression of KLF4 and c-myc is important in the induction of a stem cell phenotype and may be important in chemical carcinogenesis. The higher COX-2 in the spontaneous tumors indicates the importance of inflammation in spontaneous tumor induction. The homologous linkage groups on human chromosomes 9p21, 1p36, 9q and 8q are altered in asbestos-induced human lung adenocarcinoma. Alteration in copy number and expression of these genes may play a functional role in lung cancer development. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2345. doi:1538-7445.AM2012-2345