Squamous cell carcinoma (SCC) is one of the most common forms of skin malignancies with increasing global incidence, thus constituting a serious public health concern. Although to date the underlying genetic and epigenetic events contributing to the development and progression of SCC have been intensively studied, no resulting preventative or therapeutic strategies have been successfully developed to target this potentially lethal form of skin cancer. Therefore there is a vital need for additional studies to better understand the molecular etiology of this skin disease and harness that knowledge for the development of new and effective treatments. Evidence from our laboratory as well as others, together with the large-scale sequencing data emerging from the Cancer Genome Atlas Project, strongly suggest that the transcription factor p63, specifically the most prevalent Np63 isoforms, function as an oncogene in the early stages of SCC development. We show that overexpression of Np63 in transgenic mouse (Np63BG) skin results in a severe phenotype that share many of the underlying histological, pathological and molecular features associated with the early stages of SCC. However, our current knowledge regarding the molecular underpinnings through which Np63 functions in the early stages of SCC remains sparse. Hence, we will utilize Np63BG and Np63-GFP knock- in mice, both of which were developed in our laboratory, to address two important areas of interest. First, given the elevated levels of Np63 in SCC, we propose to experimentally evaluate the contribution of this isoform in the early stages of tumor development by performing two-stage skin chemical carcinogenesis studies on the Np63BG and Np63 heterozygous mice. Data obtained from such in vivo studies will establish the oncogenic function of Np63 and provide a better understanding of the specific role of the Np63 isoforms in the early stages of SCC initiation and progression, which to date have not been possible due to the lack of Np63 isoform specific mouse models. Secondly we propose to identify, on a genome-wide scale, Np63 specific target genes and regulatory networks contributing to the development of SCC. Towards this end, we will perform chromatin-immunoprecipitation (ChIP) followed by deep sequencing (ChIP-seq) to identify novel direct target genes of Np63, which are altered in the Np63BG mouse skin, and which likely contribute to the development of SCC. Collectively the information gleaned from these genetic studies has the potential to not only significantly enhance our molecular understanding of the underlying pathogenic alterations of SCC but also to unearth new driver pathways and critical players for future exploitation as therapeutic options.
p63 is a transcription factor that is highly overexpressed in a large number of human tumors of squamous cell origin and may play a critical role in the early stages of malignancy development and progression. Given our limited knowledge regarding the early events contributing to the development of squamous cell carcinoma (SCC), it is important to understand how altered expression levels of p63 contribute to this disease and what signaling pathways and target genes are regulated by this factor. Information obtained from such studies will be useful in identifying new diagnostic and prognostic markers of SCC and for developing effective treatment options.