TY - JOUR
T1 - Expression of cell cycle proteins in 4-(methylnitrosamino)-1-(3- pyridyl)-1-butanone-induced mouse lung tumors
AU - Sabourin, Carol L.K.
AU - Wang, Qian Shu
AU - Ralston, Sherry L.
AU - Evans, Jason
AU - Coate, Jennifer
AU - Herzog, Christopher R.
AU - Jones, Sandra L.
AU - Weghorst, Christopher M.
AU - Kelloff, Gary J.
AU - Lubet, Ronald A.
AU - You, Ming
AU - Stoner, Gary D.
N1 - Funding Information:
Received 11 March 1998; accepted 11 March 1998. This work was supported by NCI Grants CA28950 (GDS) and CA58544 (MY), and the Arthur G. James Cancer Hospital and Research Institute of The Ohio State University. The authors thank Laura A. Kresty and Charlotte Adams for expert assistance with the animal studies. The present address of Qian-Shu Wang is Department of Pharmaceutical Sciences, School of Phar-mace, University of Connecticut, Storrs, CT 06268, USA. Address correspondence to Carol L. K. Sabourin, School of Public Health, The Ohio State University, CHRI Room 1148, 300 West 10th Avenue, Columbus, OH 43210, USA. Abbreviations: Rb, retinoblastoma; NNK, 4-(methylnitrosamino)-l -(3-pyridyl)-l-butanone; cdk, cyclin dependent kinase; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; RT-PCR, reverse transcription-polymerase chain reaction; HPRT, hypoxanthineguanine phosphoribosyltransferase; SSCP, single-strand conformation polymorphism ; NSCLC, non-small cell lung cancer ; SCLC, small cell lung cancer
PY - 1998
Y1 - 1998
N2 - Cyclin D1 dysregulation and differential inactivation of p16(INK4a) and Rb have been observed in human lung cancer. In chemically induced mouse lung tumors, the p16(INK4a) 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, p16(INK4a), and Rb protein was examined by immunohistochemistry in 4- (methytnitrosamino)-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 p16(INK4a) staining. Expression of p16(INK4a), as determined by RT-PCR, was variable in lung tumors. Mutations in p16(INK4a) 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, p16(INK4a), 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.
AB - Cyclin D1 dysregulation and differential inactivation of p16(INK4a) and Rb have been observed in human lung cancer. In chemically induced mouse lung tumors, the p16(INK4a) 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, p16(INK4a), and Rb protein was examined by immunohistochemistry in 4- (methytnitrosamino)-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 p16(INK4a) staining. Expression of p16(INK4a), as determined by RT-PCR, was variable in lung tumors. Mutations in p16(INK4a) 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, p16(INK4a), 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.
KW - Cdk4
KW - Cyclin D1
KW - Lung
KW - Mouse
KW - P16(INK4a)
KW - Rb
KW - Tumor
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U2 - 10.3109/01902149809087383
DO - 10.3109/01902149809087383
M3 - Article
C2 - 9659580
AN - SCOPUS:15644373914
SN - 0190-2148
VL - 24
SP - 499
EP - 521
JO - Experimental Lung Research
JF - Experimental Lung Research
IS - 4
ER -