Expressions of junB and c-fos are enhanced in 4-nitroquinoline 1-oxide-induced rat tongue cancers.
Activator protein-1 (AP-1) is a transcription factor activated in many tumors. Using 4-nitroquinoline 1-oxide (4NQO)-induced rat tongue cancers (TC), the present study investigated the expression levels of genes that encode the components of AP-1, the jun gene family (c-jun, junB and junD) and the fos gene family (c-fos, fra-1, fra-2 and fosB). Expression levels of junB and c-fos mRNAs in TC were significantly elevated compared with those in epithelial tissue of control rat tongue, although only c-fos mRNA levels tended to be elevated in dysplastic tongue epithelium. Histologically, all 4NQO-induced rat TC were well-differentiated squamous cell carcinomas. Immunostaining for JunB and c-Fos proteins was positive in the nuclei of tumor cells of all TC. It is noteworthy that JunB was negative, but c-Fos was positive in the dysplastic tongue epithelium of the 4NQO-treated rats. Immunostaining for both proteins was negative in tongue mucosal epithelium of control rats. There were no mutations in the coding regions of either junB or c-fos in all the TC examined. These results suggest the possibility that the expressions of junB and c-fos were enhanced stepwise in 4NQO-induced carcinogenesis of rat tongue, and that the coexpression of JunB and c-Fos might play an important role in the establishment of TC.
Ohyama
Masanobu
M
Department of Oral Pathology, Kagoshima University Dental School, Kagoshima, Japan.
Hirayama
Yoshikazu
Y
Tanuma
Jun-ichi
J
Hirano
Masato
M
Semba
Ichiro
I
Shisa
Hayase
H
Hiai
Hiroshi
H
Sugihara
Kazumasa
K
Kitano
Motoo
M
D015112:4-Nitroquinoline-1-oxide / Q000633:toxicity*; D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D002467:Cell Nucleus / Q000737:chemistry / Q000473:pathology; D004195:Disease Models, Animal; D015972:Gene Expression Regulation, Neoplastic; D016762:Genes, fos / Q000235:genetics*; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D014059:Tongue / Q000737:chemistry / Q000187:drug effects / Q000473:pathology; D014062:Tongue Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology
D014408:Biomarkers, Tumor; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D015112:4-Nitroquinoline-1-oxide