P53 DOWNREGULATION IN NON-MELANOMA SKIN CANCER TREATED WITH CITRUS LIMON (CL) ESSENTIAL OIL

Abstract

Background: Citrus limon essential oil (CLEO) is rich in bioactive compounds which exhibit various therapeutic properties, including anticancer potential. Non-melanoma skin cancer, such as squamous cell carcinoma, is commonly associated with TP53gene mutations, leading to uncontrolled cell proliferation. Objectives: This study investigates the cytotoxic effects of CL EO on normal human foreskin fibroblast cells (HFF1) and human squamous carcinoma cells (A431) by analysing morphological changes, p53 protein secretion, and TP53 gene expression. Methods: HFF1 and A431 cells were treated with CLEO at concentrations of 125, 250, and 500 µg/mL for 24 hours. Morphological changes were observed using an inverted light microscope, while p53 protein secretion was analysed via Western blot. TP53 gene expression was assessed using quantitative real-time PCR. Results: There is mild structural changes in HFF1 cells at higher CLEO concentrations (250 and 500 µg/mL), whereas A431 cells exhibited significant membrane blebbing and detachment at all concentrations (125, 250, and 500 µg/mL). p53 protein secretion increased in HFF1 cells following CLEO treatment, while A431 cells exhibited a dose-dependent reduction in p53 secretion. Additionally, TP53 gene expression was significantly downregulated in A431 cells at 125 and 500 µg/mL CLEO concentrations, suggesting alternative mechanisms of cytotoxicity. Conclusion: CLEO exerts cytotoxic effects on A431 skin cancer cells than normal HFF1 cells. The modulation of p53 protein secretion and TP53 gene expression indicates its action through p53-dependent and independent mechanisms. Further studies are necessary to explore its precise molecular pathways and optimise its potential as a complementary therapy for skin cancer.