Faculty Collaboration Database

Expression of cell cycle proteins in 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced mouse lung tumors. Exp Lung Res 1998;24(4):499-521

Date

07/11/1998

Pubmed ID

9659580

DOI

10.3109/01902149809087383

Scopus ID

2-s2.0-15644373914 (requires institutional sign-in at Scopus site)   23 Citations

Abstract

Cyclin D1 dysregulation and differential inactivation of p16INK4a and Rb have been observed in human lung cancer. In chemically induced mouse lung tumors, the p16INK4a gene is a target of inactivation, and Rb is reduced at the mRNA level (Northern blot) although similar at the protein level (Western blot) when compared to normal lung tissues. The expression of cyclin D1, cdk4, p16INK4a, and Rb protein was examined by immunohistochemistry in 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced mouse lung tumors. Immunohistochemical staining revealed exclusive nuclear staining of both cyclin D1 and cdk4 that was light to moderate in normal mouse lung tissues, but intense in lung adenomas and adenocarcinomas. Western blot analysis confirmed the increased expression of cyclin D1 and cdk4 in lung tumors compared to normal lung. Immunohistochemical analyses of lung tumors showed focal areas which lacked p16INK4a staining. Expression of p16INK4a, as determined by RT-PCR, was variable in lung tumors. Mutations in p16INK4a were not found by SSCP analysis. Immunohistochemical analyses of normal lung tissues showed intense staining for Rb protein in alveolar epithelial cells and in other lung cell types; however, in the lung tumors the staining intensity was reduced and the distribution was altered. Expression of Rb was detected in normal lung tissues but was barely detectable by Northern blot hybridization in lung tumors. Western blot analysis indicated the presence of both hypophosphorylated and hyperphosphorylated Rb protein in lung tumors and in normal lung tissues. These results suggest that alterations in the cell cycle proteins, cyclin D1, cdk4, p16INK4a, and Rb, may play a role in the acquisition of autonomous growth by adenomas. Furthermore, they demonstrate the importance of immunohistochemical studies to examine expression in tissues that contain multiple cell types, such as the lung, and in tumors that by nature are heterogeneous.

Author List

Sabourin CL, Wang QS, Ralston SL, Evans J, Coate J, Herzog CR, Jones SL, Weghorst CM, Kelloff GJ, Lubet RA, You M, Stoner GD

MESH terms used to index this publication - Major topics in bold

Adenocarcinoma
Adenoma
Animals
Blotting, Western
Cell Cycle Proteins
Cyclin D1
Cyclin-Dependent Kinase Inhibitor p16
Cyclin-Dependent Kinases
DNA Mutational Analysis
DNA Primers
Immunoenzyme Techniques
Lung
Lung Neoplasms
Male
Mice
Mice, Inbred A
Nitrosamines
Polymerase Chain Reaction
RNA, Messenger
Retinoblastoma Protein