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Ki‐ras and the Characteristics of Mouse Lung Tumors
Author(s) -
Ramakrishna Gayatri,
Bialkowska Aneta,
Perella Christine,
Birely Lisa,
Fornwald Laura W.,
Diwan Bhalchandra A.,
Shiao YihHorng,
Anderson Lucy M.
Publication year - 2000
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/1098-2744(200007)28:3<156::aid-mc4>3.0.co;2-m
Subject(s) - biology , oncogene , cancer research , carcinogenesis , lung , kinase , mutation , cell growth , adenocarcinoma , gtp' , point mutation , cell , microbiology and biotechnology , cell cycle , pathology , cancer , gene , medicine , genetics , enzyme , biochemistry
Codon 12 mutations are frequent in the Ki‐ ras oncogene in human lung adenocarcinomas, but the effects of these alterations have not been well characterized in lung epithelial cells. Murine primary lung tumors derived from peripheral epithelial cells also may present Ki‐ ras mutations and are useful models for study of early phases of tumor development. One hypothesis is that Ki‐ ras mutation and/or a Ki‐ras p21 increase could enhance Ki‐ras p21‐GTP and cell‐cycle stimulation through raf‐1 and extracellularly regulated protein kinases (Erks). We examined lung tumors 1–7 mm in largest dimension initiated in male Swiss mice by N ‐nitrosodimethylamine for pathologic type, Ki‐ ras mutations and levels of total Ki‐ras p21, Ki‐ras p21 bound to GTP, raf‐1, Erk1 and Erk2 and their phosphorylated (activated) forms, and proliferating cell nuclear antigen. Total Ki‐ras p21 and activated ras‐GTP were not significantly greater in tumors than in normal lung or in tumors with versus those without Ki‐ ras mutations. Carcinomas with Ki‐ ras mutations were significantly smaller than those without mutations. Carcinomas were significantly larger than adenomas only for tumors without mutations. High levels of Erk2 and correlation of Erk2 amount with ras‐GTP were specific characteristics of tumors with Ki‐ ras mutations. Size of all tumors correlated with ras‐GTP but not with proliferating cell nuclear antigen. Raf‐1 was expressed mainly in alveolar macrophages in normal lung but was focally upregulated in papillary areas of some tumors. The results indicate that Ki‐ras influences the characteristics of lung tumors, but a linear ras–raf–Erk–cell‐cycle control sequence does not adequately characterize tumorigenic events in this model. Mol. Carcinog. 28:156–167, 2000. © 2000 Wiley‐Liss, Inc.