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Present and future perspectives of photodynamic therapy for cutaneous squamous cell carcinoma
摘要： Cutaneous squamous cell carcinoma (SCC) is the second most common skin cancer. Surgery remains the main stay of treatment, but some patients are not eligible for surgery and, more importantly, lesions at critical sites need nonsurgical approaches for tissue preservation. In this context, photodynamic therapy (PDT) has been extensively studied as noninvasive or minimally invasive treatment, and studies have shown promising results in terms of safety, efficacy, and cosmetic outcome. Also, studies have proposed different mechanism for its efficacy. However, human studies demonstrating its efficacy are limited in terms of sample size and tumor depth of invasion. Good results are mainly seen in case reports of microinvasive SCC, which is defined as SCC limited to papillary dermis. This inadequacy is due to inadequate penetration of topically applied photosensitizers through keratinized tumor surfaces. To overcome these hurdles, pretreatment with lasers or microneedles and encapsulation of photosensitizers into nanoparticles have been tried. Hence, the present article will discuss studies that have demonstrated the efficacy and safety of PDT for cutaneous SCC, studies that have postulated the mechanism of action of PDT, agents that have been used as PDT enhancers, and finally, the recent use of adjuvant therapy in combination with PDT.
关键词： mechanism of action,surgery,photodynamic therapy,nanomedicine,cutaneous squamous cell carcinoma
更新于2025-09-19 17:15:36
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Brahma deficiency in keratinocytes promotes UV carcinogenesis by accelerating the escape from cell cycle arrest and the formation of DNA photolesions
摘要： Background: Ultraviolet radiation (UVR) is the principal cause of keratinocyte skin cancers. Previous work found that levels of the chromatin remodelling protein, Brahma (Brm), are diminished during the progression from actinic keratoses to cutaneous squamous cell carcinomas in humans, and its loss in UV-irradiated mouse skin causes epidermal hyperplasia and increased tumour incidence. Methods: The skins of mice and mouse and human keratinocytes deficient in Brm were exposed to UVR and evaluated for cell cycle progression and DNA damage response. Objective: To identify the mechanisms by which loss of Brm contributes to UVR-induced skin carcinogenesis. Results: In both mouse keratinocytes and HaCaT cells, Brm deficiency led to an increased cell population growth following UVR exposure compared to cells with normal levels of Brm. Cell cycle analysis using a novel assay showed that Brm-deficient keratinocytes entered cell cycle arrest normally, but escaped from cell cycle arrest faster, enabling them to begin proliferating earlier. In mouse keratinocytes, Brm primarily affected accumulation in G0/G1-phase, whereas in HaCaT cells, which lack normal p53, accumulation in G2/M-phase was affected. Brm-deficient keratinocytes in mouse skin and human cell cultures also had higher levels of UVR-induced cyclobutane pyrimidine dimer photolesions. These effects occurred without any compensatory increase in DNA repair or cell death to remove photolesions or the cells that harbor them from the keratinocyte population. Conclusion: The loss of Brm in keratinocytes exposed to UVR enables them to resume proliferation while harboring DNA photolesions, leading to an increased fixation of mutations and, consequently, increased carcinogenesis.
关键词： SWI/SNF,Cutaneous squamous cell carcinoma,UV radiation,Cell cycle arrest,DNA damage
更新于2025-09-04 15:30:14