Keratinocyte Carcinoma and Photoprevention:The Protective Actions of Repurposed Pharmaceuticals, Phytochemicals and Vitamins

SIMPLE SUMMARY: Keratinocyte carcinoma is the most common type of cancer. Sun exposure and ultraviolet radiation are significant contributors to the development of carcinogenesis, mediated by DNA damage, increased oxidative stress, inflammation, immunosuppression and dysregulated signal transduction. Photoprevention involves using different compounds to delay or prevent ultraviolet radiation-induced skin cancer. In this review, we look at new avenues for systemic photoprevention that are based on pharmaceuticals, plant-derived phytochemicals and vitamins. We also investigate the mechanisms underlying these strategies for preventing the onset of carcinogenesis. ABSTRACT: Ultraviolet radiation (UVR) arising from sun exposure represents a major risk factor in the development of keratinocyte carcinomas (KCs). UVR exposure induces dysregulated signal transduction, oxidative stress, inflammation, immunosuppression and DNA damage, all of which promote the induction and development of photocarcinogenesis. Because the incidence of KCs is increasing, better prevention strategies are necessary. In the concept of photoprevention, protective compounds are administered either topically or systemically to prevent the effects of UVR and the development of skin cancer. In this review, we provide descriptions of the pathways underlying photocarcinogenesis and an overview of selected photoprotective compounds, such as repurposed pharmaceuticals, plant-derived phytochemicals and vitamins. We discuss the protective potential of these compounds and their effects in pre-clinical and human trials, summarising the mechanisms of action involved in preventing photocarcinogenesis

Off-Label 9-Valent Human Papillomavirus Vaccination for Actinic Keratosis:A Case Series

BACKGROUND: The suspected link between human papillomavirus (HPV) and the development of premalignant and malignant skin lesions remains inadequately examined in clinical settings. This case series describes HPV vaccination as an off-label adjuvant therapy for actinic keratosis (AK). METHODS: Twelve immunocompetent AK patients underwent HPV vaccination at a private dermatology clinic in Naestved, Denmark. Prior to vaccination, all patients demonstrated a high AK burden that required regular control visits. At 0, 2, and 6 months, the patients received an intramuscular injection of a commercially available 9-valent HPV vaccine. Concurrently, patients continued conventional AK therapies at 3-month intervals. Clinical response, consisting of reduction in AK number and general change in skin appearance, was assessed by a dermatologist over 12 months following first vaccination. RESULTS: All patients (mean age 76.2 years; 10 M and 2 F) completed the vaccine schedule. Overall, an average 85% reduction in total AK burden was recorded 12 months after beginning vaccination. Median AK burden thus fell from 56 (IQR: 44–80) to 13.5 (IQR: 1–18) lesions after 12 months. Lesion reduction was observable by the second inoculation at month 2 (34 AKs; IQR 22–80), continuing steadily until month 6 (15 AKs; IQR 5–30) and plateauing between 6 and 12 months. Clinically, HPV vaccination elicited fading of lesions' erythematous background after the first dose, often followed by sloughing of hyperkeratotic elements in subsequent weeks. Patients reported no adverse effects related to HPV vaccination. CONCLUSION: This case series introduces the possibility that 9-valent HPV vaccination in combination with conventional treatments may be used as a therapeutic strategy for AK

Impact of UVR Exposure Pattern on Squamous Cell Carcinoma-A Dose–Delivery and Dose–Response Study in Pigmented Hairless Mice

Cumulative lifetime ultraviolet radiation (UVR) is an important factor in the development of squamous cell carcinoma. This study examines the impact of UVR exposure pattern on tumor development. Hairless C3.Cg/TifBomTac immunocompetent pigmented mice (n = 351) were irradiated with 12 standard erythema doses (SED)/week, given as 2 SED ×6, 3 SED ×4, 4 SED ×3, or 6 SED ×2 (dose–delivery study) or 0, 0.6, 1.2, 2, 3 or 4 SED ×3/week (dose–response study). All mice were irradiated until development of 3 tumors of 4 mm each. Pigmentation was measured once monthly. In the dose–delivery study, the median time until tumor development was independent of dose fractions. In the dose–response study, higher UVR doses resulted in faster tumor appearance. When the weekly UVR dose was decreased from 12 to 6 SED, the cumulative UVR dose needed for tumor development was reduced by 40%. In conclusion, delivery schedules of a fixed weekly UVR dose did not affect tumor development. When using different weekly UVR doses, longer time to tumor development was observed using lower UVR doses. Lower weekly UVR doses however resulted in lower cumulative UVR doses to induce tumors in hairless pigmented mice