Expression profiling of cutaneous squamous cell carcinoma with perineural invasion implicates the p53 pathway in the process

Abstract

Squamous cell carcinoma (SCC) is the second most common cancer worldwide and accounts for approximately 30% of all keratinocyte cancers. The vast majority of cutaneous SCCs of the head and neck (cSCCHN) are readily curable with surgery and/or radiotherapy unless high-risk features are present. Perineural invasion (PNI) is recognized as one of these high-risk features. The molecular changes during clinical PNI in cSCCHN have not been previously investigated. In this study, we assessed the global gene expression differences between cSCCHN with or without incidental or clinical PNI. The results of the analysis showed signatures of gene expression representative of activation of p53 in tumors with PNI compared to tumors without, amongst other alterations. Immunohistochemical staining of p53 showed cSCCHN with clinical PNI to be more likely to exhibit a diffuse over-expression pattern, with no tumors showing normal p53 staining. DNA sequencing of cSCCHN samples with clinical PNI showed no difference in mutation number or position with samples without PNI, however a significant difference was observed in regulators of p53 degradation, stability and activity. Our results therefore suggest that cSCCHN with clinical PNI may be more likely to contain alterations in the p53 pathway, compared to cSCCHN without PNI.

Molecular mechanisms of perineural spread of cutaneous carcinoma: a potential role for receptor tyrosine kinases and other biomarkers

“…(142) This study identified a wide range of genes that were differentially up or downregulated across the groups. Several statistically and biologically significant differentials were identified, including downregulation of transglutaminase 3 (TGM3) and up-regulation of lysyl oxidase like 2 (LOXL2) and EphA3 in the perineural spread cohort (Figure 11).…”

“…TGM3 and LOXL2 were selected for further study in the subcutaneous mouse model, however due to small numbers and variable tumour growth no significant conclusions could be drawn. (51,142) Generous provision of the raw microarray data allowed differential expression levels of Eph receptors and ephrin ligands to be specifically reviewed as part of this thesis (Table 5). In addition to up-regulation of EphA3, EphA4 and EphA5 were elevated without reaching statistical significance.…”

“…Subsequent pathway analysis by our collaborators revealed genetic signatures representative of activation of the p53 pathway in cSCCHN with perineural spread compared to cSCCHN without perineural involvement. (142) The authors proceeded to examination of p53 at the protein level by immunohistochemistry, which revealed an absence of normal p53 staining in all tumours with PNS and a preponderance of a diffuse over-expression pattern. Although this did not correlate with a difference in p53 mutation number or position there was a significant differential observed in regulators of p53 stability, activity and degradation consistent with dysregulation of the p53 pathway in cSCCHN with perineural spread.…”

“…The p53 pathway clearly warrants further investigation in perineural spread, building on the earlier work of our colleagues. (142) p16 is another well recognised cell cycle regulator that is implicated in carcinogenesis and tumour progression that has not previously profiles of these biomarkers in perineural spread of cSCCHN.…”

“…(142) Appropriate positive and negative controls were included in each run. In our study, we performed immunohistochemistry for 10/20 specimens.…”