Molecular profiling of cutaneous squamous cell carcinomas and actinic keratoses from organ transplant recipients

Abstract

BackgroundThe risk of developing cutaneous squamous cell carcinoma (SCC) is markedly increased in organ transplant recipients (OTRs) compared to the normal population. Next to sun exposure, the immunosuppressive regimen is an important risk factor for the development of SCC in OTRs. Various gene mutations (e.g. TP53) and genetic alterations (e.g. loss of CDKN2A, amplification of RAS) have been found in SCCs. The aim of this genome-wide study was to identify pathways and genomic alterations that are consistently involved in the formation of SCCs and their precursor lesions, actinic keratoses (AKs).MethodsTo perform the analysis in an isogenic background, RNA and DNA were isolated from SCC, AK and normal (unexposed) epidermis (NS) from each of 13 OTRs. Samples were subjected to genome-wide expression analysis and genome SNP analysis using Illumina’s HumanWG-6 BeadChips and Infinium II HumanHap550 Genotyping BeadChips, respectively. mRNA expression results were verified by quantitative PCR.ResultsHierarchical cluster analysis of mRNA expression profiles showed SCC, AK and NS samples to separate into three distinct groups. Several thousand genes were differentially expressed between epidermis, AK and SCC; most upregulated in SCCs were hyperproliferation related genes and stress markers, such as keratin 6 (KRT6), KRT16 and KRT17. Matching to oncogenic pathways revealed activation of downstream targets of RAS and cMYC in SCCs and of NFκB and TNF already in AKs. In contrast to what has been reported previously, genome-wide SNP analysis showed very few copy number variations in AKs and SCCs, and these variations had no apparent relationship with observed changes in mRNA expression profiles.ConclusionVast differences in gene expression profiles exist between SCC, AK and NS from immunosuppressed OTRs. Moreover, several pathways activated in SCCs were already activated in AKs, confirming the assumption that AKs are the precursor lesions of SCCs. Since the drastic changes in gene expression appeared unlinked to specific genomic gains or losses, the causal events driving SCC development require further investigation. Other molecular mechanisms, such as DNA methylation or miRNA alterations, may affect gene expression in SCCs of OTRs. Further study is required to identify the mechanisms of early activation of NFκB and TNF, and to establish whether these pathways offer a feasible target for preventive intervention among OTRs.

Systematical Analysis of Cutaneous Squamous Cell Carcinoma Network of microRNAs, Transcription Factors, and Target and Host Genes

“…Analysis by quantitative reverse transcription-PCR revealed that PKC-delta RNA was reduced an average of 90% in the SCCs tested, consistent with PKC-delta down-regulation at the protein level (Yadav et al, 2010). Loss of CDKN2A were found in SCCs (Hameetman et al, 2013). Researches imply that an important component of the early stages in squamous carcinoma progression may be a modest decrease in RalA gene expression that magnifies the effects of decreased E-cadherin expression by promoting its degradation (Sowalsky et al, 2010).…”

“…A large amount of data is available on the functional impact of missense mutations in TP53 and on mutation patterns in many different cancers . Researchers suggest that immunohistochemical analysis of TP53 protein expression and fluorescent in situ hybridization of TP53 gene could be applied as screening tool for microinvasion of oral squamous cell carcinoma (Heah et al, 2011). In the abnormally expressed network TP53 regulates four miRNAs (hsa-miR-34a, hsa-miR-125b, hsa-miR-143 and hsa-miR-145).…”

“…In cSCC.Matrix metallopeptidase 13 (MMP13) was identified as a direct target suppressed by miR-125b (Xu et al, 2012). Keratin 6 (KRT6), KRT16 and KRT17 are upregulated in SCCs (Hameetman et al, 2013). Increased expression of KLF4 protein and mRNA were found in squamous cell carcinoma cell line studies and fresh skin tissue respectively, using western blotting and semiquantitative real time polymerase chain reaction (Chen et al, 2008).…”

The chemokine microenvironment of Squamous Cell Carcinoma and its precursor lesions

“…Prognostically, higher levels of VEGF and Microvessel Density (MVD) are associated with worse overall mortality in HNSCC, but interestingly not with risk of metastasis 82 .…”

The skin microbiopsy

“…However, the majority of the actinic keratoses do not go on to become SCC (Feldman andFleischer, 2011, Fuchs and. Molecular profiling of AK, SCC and normal skin suggested that the dysplastic lesions and carcinomas share certain differentially expressed genes (Hameetman et al, 2013, Padilla et al, 2010.…”