Multiple genetic mutations with subsequent molecular events are required for progression of normal epithelial cells to cancer, with p53 mutations being a very common event in squamous carcinogenesis. Upregulation of nuclear factor kappa B (NF-κB) is an associated feature of malignancy, however studies have not examined purposeful overexpression of the NF-κB p65 subunit in in vitro models of oral carcinogenesis. Our objective is to demonstrate that NF-κB p65 transfection into p53 deficient Rhek keratinocytes produces carcinogenic progression. We constitutively over-expressed NF-κB p65 in Rhek keratinocytes, previously immortalized by SV 40 thus inactivating p53, and studied NF-κB dependent events. NF-κB p65 overexpression provided functional upregulation of NF-κB and produced cyclin D1-mediated proliferation and interleukin 8 transcription and secretion. Consequently, we demonstrated tumorigenesis in athymic mice with NF-κB p65 overexpressing cells. We conclude NF-κB p65 overexpression in p53 inactivated immortalized keratinocytes produces tumorigenesis, and that this single alteration in NF-κB expression on a p53 inactivated background is sufficient for squamous carcinogenesis features, thus providing evidence that p65 may act as a gain of function oncogene in this setting.
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