Reduced P53 Staining in Actinic Keratosis is Associated with Squamous Cell Carcinoma: A Preliminary Study

P53 staining index and zonal staining patterns in actinic keratoses

Actinic keratoses (AKs) are common dysplastic lesions resulting from chronic excessive ultraviolet exposure. Neither the clinical grade of thickness nor the histological grade of dysplasia seems valid predictors of aggressive potential of AKs. Instead, the mutational status in AKs appears to predict well the clinical course. TP53 gene mutations result in a non-functional protein resistant to degradation, thus immunohistochemical staining for p53 can suggest mutation status. Increased p53 was associated with progression from AK to squamous cell carcinoma. To investigate how the intensity of p53 staining (p53 staining index) varies according to body site, histological subtype and grade dysplasia of AKs. Secondly, we sought to investigate the distribution in the epidermal layers of non-functional p53 (zonal staining patterns). p53 staining index was greater than 50% in 90.7% of AKs. p53 staining index was significantly higher in older age (p < 0.0093) and in facial AKs compared to other body areas (p = 0.03). A significant correlation between p53 staining index and grade of dysplasia was observed (p = 0.006) and between p53 staining index and zonal p53 staining pattern (p = 0.003). No significant differences in p53 staining index among the various histological AK types were observed. No correlation between clinical and histological grade. All AKs, independently from their clinical appearance, should be treated but special attention is required for AKs on severely photodamaged skin on the face and in older patients.

Gene Expression Patterns of Cutaneous Squamous Cell Carcinoma and Actinic Keratosis: Biomarkers Screening for Skin Disease Diagnosis

Background

Actinic keratosis (AK) was an intraepidermal tumor which caused by ultraviolet irradiation-induced skin damage.

Objective

The aim was to screen biomarkers for development of skin disease by comparing the gene expression profiles between cutaneous squamous cell carcinoma (CSCC) and AK.

Methods

GSE45216 with 30 cutaneous squamous cell carcinoma patients and 10 actinic keratosis patients were downloaded and significance analysis of microarrays was processed to screen differently expressed genes (DEGs). Fisher's exact test was processed for DEGs enrichment. Pathway relationship network systematically reflected the signal conduction and synergism between enriched pathways based on Kyoto Encyclopedia of Genes and Genomes database. Gene co-expression network was constructed according to gene expression data. Quantitative real-time-PCR was used to verify screened biomarkers.

Results

Total 410 DEGs were screened and enriched into various functions, such as signal transduction and negative regulation of apoptotic process. They also participated into cytokine-cytokine receptor interaction and focal adhesion. The pathway relationship network was constructed with 27 nodes. Hub nodes with higher degree of this network were mitogen-activated protein kinase signaling pathway and apoptosis. The gene co-expression network was constructed with 39 nodes. Thereinto, hub node was ELOVL fatty acid elongase. The expression levels of ELOVL4 and HPGD were significantly higher in CSCC samples than that in AK samples, while the expression levels of INHBA and LAMC2 in CSCC samples were significantly lower than that in AK samples.

Conclusion

These screened genes, including ELOVL4, HPGD, INHBA and LAMC2, played important roles in transformation from AK to CSCC.

How to treat actinic keratosis? An update

Actinic keratosis (AKs) is one of the most common skin lesions leading to an increased risk of developing squamous cell carcinoma and other skin malignancies. The lesions principally arise as a result of excessive ultraviolet (UV) exposure. AKs may regress spontaneously, remain stable or evolve to invasive squamous cell carcinoma. The risk of squamous cell carcinoma is significantly increased patients with more than 5 AKs. The main mechanisms involved in the formation of AK are inflammation, mutagenesis, oxidative stress, impaired apoptosis, immunosuppression, disregulation of cell growth and proliferation, and tissue remodeling. Human papilloma virus has also been correlated with the formation of some AKs. As an individual ages, his skin is exposed to increasing cumulative amounts of UV light and other environmental insults. This is especially true for the head, neck and forearms. These insults do not target only the skin where individual lesions develop, but also the surrounding area. In this area undetectable preclinical AK lesions or dysplastic cells may be present. The whole affected area is known as the 'field'. Therefore, management is divided into lesion-directed and field-directed therapies. Currently, the therapies in use are lesion-directed cryotherapy and/or excision, and field-directed topical agents: 5-fluorouracil, diclofenac, photodynamic therapy, imiquimod, and ingenol mebutate. Combining lesion- and field-directed therapies showed good results and several novel therapies are under investigation. Treatment is variable and personalized, what makes a gold standard management algorithm difficult to design. This review aims to describe the rationale behind the available treatment options for AKs based on current understanding of pathophysiology and epidemiology.

Actinic keratosis: rationale and management

Actinic keratoses (AKs) are common skin lesions heralding an increased risk of developing squamous cell carcinoma (SCC) and other skin malignancies, arising principally due to excessive ultraviolet (UV) exposure. They are predominantly found in fair-skinned individuals, and increasingly, are a problem of the immunosuppressed. AKs may regress spontaneously, remain stable or transform to invasive SCC. The risk of SCC increases for those with more than 5 AKs, and the majority of SCCs arise from AKs. The main mechanisms of AK formation are inflammation, oxidative stress, immunosuppression, impaired apoptosis, mutagenesis, dysregulation of cell growth and proliferation, and tissue remodeling. Human papilloma virus has also been implicated in the formation of some AKs. Understanding these mechanisms guides the rationale behind the current available treatments for AKs. One of the main principles underpinning the management of AKs is that of field cancerization. Wide areas of skin are exposed to increasing amounts of UV light and other environmental insults as we age. This is especially true for the head, neck and forearms. These insults do not target only the skin where individual lesions develop, but also large areas where crops of AKs may appear. The skin between lesions is exposed to the same insults and is likely to contain as-yet undetectable preclinical lesions or areas of dysplastic cells. The whole affected area is known as the ‘field’. Management is therefore divided into lesion-directed and field-directed therapies. Current therapies include lesion-directed cryotherapy and/or excision, and topical field-directed creams: 5-fluorouracil, imiquimod, diclofenac, photodynamic therapy and ingenol mebutate. Combining lesion- and field-directed therapies has yielded good results and several novel therapies are under investigation. Treatment is variable and tailored to the individual making a gold standard management algorithm difficult to design. This literature review article aims to describe the rationale behind the best available therapies for AKs in light of current understanding of pathophysiology and epidemiology. A PubMed and MEDLINE search of literature was performed between January 1, 2000 and September 18, 2013. Where appropriate, articles published prior to this have been referenced. This is not a systematic review or meta-analysis, but aims to highlight the most up to date understanding of AK disease and its management.