Integrative mRNA profiling comparing cultured primary cells with clinical samples reveals PLK1 and C20orf20 as therapeutic targets in cutaneous squamous cell carcinoma

Abstract

Identifying therapeutic targets for cancer treatment relies on consistent changes within particular types or sub-types of malignancy. The ability to define either consistent changes or sub-types of malignancy is often masked by tumor heterogeneity. To elucidate therapeutic targets in cutaneous squamous cell carcinoma (cSCC), the most frequent skin neoplasm with malignant potential, we have developed an integrated approach to gene expression profiling beginning with primary keratinocytes in culture. Candidate drivers of cSCC development were derived by first defining a set of in vitro cancer genes and then comparing their expression in a range of clinical data sets containing normal skin, cSCC and the benign hyper-proliferative condition psoriasis. A small interfering RNA (siRNA) screen of the resulting 21 upregulated genes has yielded targets capable of reducing xenograft tumor volume in vivo. Small-molecule inhibitors for one target, Polo-like kinase-1 (PLK1), are already in clinical trials for other malignancies, and our data show efficacy in cSCC. Another target, C20orf20, is identified as being overexpressed in cSCC, and siRNA-mediated knockdown induces apoptosis in vitro and reduces tumor growth in vivo. Thus, our approach has shown established and uncharacterized drivers of tumorigenesis with potent efficacy as therapeutic targets for the treatment of cSCC.

Novel CARD11 Mutations in Human Cutaneous Squamous Cell Carcinoma Lead to Aberrant NF-κB Regulation

“…Consistent with our immunofluorescence data, analysis of our previous microarray data 34 showed that CARD11 mRNA expression was increased in primary cultured cSCC keratinocytes compared with normal primary keratinocytes and significantly increased in cSCC tissue compared with normal skin (P Z 0.0067). CARD14 expression was comparable with CARD11 in vitro and in vivo but was not altered in cSCC ( Figure 4B).…”

“…Each show increased proliferation, inflammation, and delayed differentiation, however, cSCC is malignant and psoriasis benign. We and others have exploited these properties to identify gene expression changes specific to cSCC, 34,41 and it is tempting to speculate that at least some of the differences between these two diseases may be mediated through differential CARD signal transduction. It is important to note that CARD scaffold proteins can signal through pathways other than NF-kB, such as Jun N-terminal kinase.…”

“…Control indicates the omission of the primary antibody in normal human skin, DAPI highlights nuclei. B: Raw signal intensities from bead-array experiments performed previously 34 were searched for CARD11 and CARD14 expression in vitro (left graph) and in vivo (right graph). Each graph (1 Â CARD11, 3 Â CARD14) represents a separate probe on the array.…”

Genetic Predisposition to Cutaneous Squamous Cell Carcinoma

“…As discussed in the introduction, various independent studies conducted thus far have revealed heterogeneity in the incidence of RAS mutations in human cSCC and we have been unable to detect RAS mutations in six RDEB SCC patients and four non-RDEB SCC patient samples (Pourreyron et al, 2007). Similar to non-RDEB SCC data a proportion of RDEB tumours harbour TP53 mutation and CDKN2A methylation/ aberrant expression (Arbiser et al, 2004;Watt et al, 2011). In the following section we discuss the various ideas and studies investigating aspects of RDEB and RDEB SCC pathology.…”

“…To date no single study has identified a distinct difference in the histology or expression of markers both at the mRNA or protein level when comparing cSCC from RDEB patients with cSCC in the general population. We have recently tried to address this question with a gene expression study utilising microarrays containing more than 47,000 probes to interrogate RNA isolated from primary cSCC keratinocytes isolated from RDEB and non-RDEB patients (Watt et al, 2011).…”