c-fos-induced osteosarcoma formation in transgenic mice: cooperativity with c-jun and the role of endogenous c-fos.
Transgenic mice overexpressing the c-fos proto-oncogene in bone develop osteosarcomas, whereas mice overexpressing c-Jun are normal. In this study, we investigated whether Fos and Jun would cooperate in vivo and whether the threshold levels of Fos are important in osteosarcoma formation. Fos-Jun double-transgenic mice develop osteosarcomas at a higher frequency than single-Fos transgenic mice with no differences in the time of onset of tumor formation. Histological and histochemical analyses indicated that Fos-Jun tumors contained greater quantities of neoplastic bone, were more remodeled, and contained a greater number of multinucleated osteoclast-like cells than tumors isolated from age-matched, single transgenic littermates. In contrast, overexpression of Fos in knockout mice that lack endogenous Fos resulted in a decrease in the number of tumor-bearing mice; osteosarcomas were almost absent in c-fos -/- mice, whereas tumor incidence was reduced to approximately 50% in c-fos +/- mice. Cell lines isolated from Fos-Jun transgenic tumors expressed high levels of both transgenes but significantly lower levels of the jun-related gene junB compared with cells expressing only a c-fos transgene. Osteoblastic marker genes were expressed at varying levels in different cell lines, but expression of interstitial collagenase (matrix metalloproteinase-1) was enhanced in cells derived from Fos-Jun tumors. These studies demonstrate that coexpression of a c-jun transgene can enhance Fos-induced oncogenesis in vivo and suggest that a critical level of Fos is necessary for osteosarcoma development.
Wang
Z Q
ZQ
Research Institute of Molecular Pathology, Vienna, Austria.
Liang
J
J
Schellander
K
K
Wagner
E F
EF
Grigoriadis
A E
AE
D000818:Animals; D001859:Bone Neoplasms / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D016762:Genes, fos; D016758:Genes, jun; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000166:cytology; D012516:Osteosarcoma / Q000235:genetics*; D016760:Proto-Oncogene Proteins c-fos / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D016019:Survival Analysis; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014407:Tumor Cells, Cultured
D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D018808:Transcription Factor AP-1