The effect of ultraviolet radiation on the transforming growth factor beta 1/Smads pathway and p53 in actinic keratosis and normal skin

Advancements in elucidating the pathogenesis of actinic keratosis: present state and future prospects

Solar keratosis, also known as actinic keratosis (AK), is becoming increasingly prevalent. It is a benign tumor that develops in the epidermis. Individuals with AK typically exhibit irregular, red, scaly bumps or patches as a result of prolonged exposure to UV rays. These growths primarily appear on sun-exposed areas of the skin such as the face, scalp, and hands. Presently, dermatologists are actively studying AK due to its rising incidence rate in the United States. However, the underlying causes of AK remain poorly understood. Previous research has indicated that the onset of AK involves various mechanisms including UV ray-induced inflammation, oxidative stress, complex mutagenesis, resulting immunosuppression, inhibited apoptosis, dysregulated cell cycle, altered cell proliferation, tissue remodeling, and human papillomavirus (HPV) infection. AK can develop in three ways: spontaneous regression, persistence, or progression into invasive cutaneous squamous cell carcinoma (cSCC). Multiple risk factors and diverse signaling pathways collectively contribute to its complex pathogenesis. To mitigate the risk of cancerous changes associated with long-term UV radiation exposure, prompt identification, management, and prevention of AK are crucial. The objective of this review is to elucidate the primary mechanisms underlying AK malignancy and identify potential treatment targets for dermatologists in clinical settings.

Targeting ferroptosis in melanoma: cancer therapeutics

Melanoma is an aggressive kind of skin cancer; its rate has risen rapidly over the past few decades. Melanoma reports for only about 1% of skin cancers but leads to a high majority of skin cancer deaths. Thus, new useful therapeutic approaches are currently required, to state effective treatments to consistently enhance the overall survival rate of melanoma patients. Ferroptosis is a recently identified cell death process, which is different from autophagy, apoptosis, necrosis, and pyroptosis in terms of biochemistry, genetics, and morphology which plays an important role in cancer treatment. Ferroptosis happens mostly by accumulating iron and lipid peroxides in the cell. Recently, studies have revealed that ferroptosis has a key role in the tumor's progression. Especially, inducing ferroptosis in cells can inhibit the tumor cells' growth, leading to back warding tumorigenesis. Here, we outline the ferroptosis characteristics from its basic role in melanoma cancer and mention its possible applications in melanoma cancer treatment. Video Abstract.

Current understanding of epigenetics role in melanoma treatment and resistance

Melanoma is the most aggressive form of skin cancer resulting from genetic mutations in melanocytes. Several factors have been considered to be involved in melanoma progression, including genetic alteration, processes of damaged DNA repair, and changes in mechanisms of cell growth and proliferation. Epigenetics is the other factor with a crucial role in melanoma development. Epigenetic changes have become novel targets for treating patients suffering from melanoma. These changes can alter the expression of microRNAs and their interaction with target genes, which involves cell growth, differentiation, or even death. Given these circumstances, we conducted the present review to discuss the melanoma risk factors and represent the current knowledge about the factors related to its etiopathogenesis. Moreover, various epigenetic pathways, which are involved in melanoma progression, treatment, and chemo-resistance, as well as employed epigenetic factors as a solution to the problems, will be discussed in detail.

Identification of key genes in cutaneous squamous cell carcinoma: a transcriptome sequencing and bioinformatics profiling study

Background

Long-term exposure to ultraviolet (UV) radiation can cause cutaneous squamous cell carcinoma (cSCC), which is one of the most common malignant cancers worldwide. Actinic keratosis (AK) is generally considered a precancerous lesion of cSCC. However, the pathogenesis and oncogenic processes of AK and cSCC remain elusive, especially in the context of photodamage.

Methods

In this study, transcriptome sequencing was performed on AK, cSCC, normal sun-exposed skin (NES) tissues, and normal non-sun-exposed skin (NNS) from 24 individuals. Bioinformatics analysis to identify the differentially expressed genes (DEGs) of 4 groups, and potential key genes of cSCC were validated by real-time quantitative reverse transcription PCR (qRT-PCR).

Results

A total of 46,930 genes were differentially expressed in the 4 groups, including 127 genes that were differentially expressed between NES and NNS, 420 DEGs in AK compared to NES, 1,658 DEGs in cSCC compared to NES, and 1,389 DEGs in cSCC compared to AK. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis suggested that the DEGs are involved in multiple pathways, including extracellular matrix (ECM)-receptor interaction, immune, inflammatory, microbial infection, and other related pathways. Finally, 5 new genes (HEPHL1, FBN2, SULF1, SULF2, and TCN1) were confirmed significantly upregulated in cSCC.

Conclusions

Using transcriptome sequencing and integrated bioinformatical analysis, we have identified key DEGs and pathways in cSCC, which could improve our understanding of the cause and underlying molecular events of AK and cSCC. HEPHL1, FBN2, SULF1, SULF2, and TCN1 may be novel potential biomarkers and therapeutic targets of cSCC.

Molecular Profile of Skin Cancer

Neoplasia occurs as a result of genetic mutations. Research evaluating the association between gene mutations and skin cancer is limited and has produced inconsistent results. There are no established guidelines for screening skin cancer at molecular level. It should also be noted that the combinations of some mutations may play a role in skin tumors’ biology and immune response. There are three major types of skin cancer, and the originality of this study comes from its approach of each of them.

Inflammatory Molecules Associated with Ultraviolet Radiation-Mediated Skin Aging

Skin is the largest and most complex organ in the human body comprised of multiple layers with different types of cells. Different kinds of environmental stressors, for example, ultraviolet radiation (UVR), temperature, air pollutants, smoking, and diet, accelerate skin aging by stimulating inflammatory molecules. Skin aging caused by UVR is characterized by loss of elasticity, fine lines, wrinkles, reduced epidermal and dermal components, increased epidermal permeability, delayed wound healing, and approximately 90% of skin aging. These external factors can cause aging through reactive oxygen species (ROS)-mediated inflammation, as well as aged skin is a source of circulatory inflammatory molecules which accelerate skin aging and cause aging-related diseases. This review article focuses on the inflammatory pathways associated with UVR-mediated skin aging.

TGFβ Signaling in Photoaging and UV-Induced Skin Cancer

UVR is a major etiology for premature skin aging that leads to photoaging and UV-induced skin cancers. In the skin, TGFβ signaling is a growth inhibitor for keratinocytes and a profibrotic factor in the dermis. It exerts context-dependent effects on tumor progression. Chronic UV exposure likely causes TGFβ1/SMAD3 signaling activation and contributes to metalloproteinase-induced collagen degradation and photoinflammation in photoaging. UV irradiation also causes gene mutations in key elements of the TGFβ pathway, including TGFβRI, TGFβRII, SMAD2, and SMAD4. These mutations enable tumor cells to escape from TGFβ-induced growth inhibition and induce genomic instability and cancer stem cells, leading to the initiation, progression, invasion, and metastasis of cutaneous squamous cell carcinoma (cSCC). Furthermore, UV-induced mutations cause TGFβ overexpression in the tumor microenvironment (TME) of cSCC, basal cell carcinoma (BCC), and cutaneous melanoma, resulting in inflammation, angiogenesis, cancer-associated fibroblasts, and immune inhibition, supporting cancer survival, immune evasion, and metastasis. The pleiotropic effects of TGFβ provide possible treatment options for photoaging and skin cancer. Given the high UV-induced mutational burden and immune-repressive TME seen in cSCC, BCC, and cutaneous melanoma, treatment with the combination of a TGFβ signaling inhibitor and immune checkpoint blockade could reverse immune evasion to reduce tumor growth.

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.

The role of ultraviolet radiation in the pathogenesis of pterygia (Review)

Pterygium is a common ophthalmic disease affecting humans only. Extensive epidemiological data have demonstrated a causative effect of chronic ultraviolet (UV) radiation on pterygia. Progress has been made in determining the origin of pterygia, their nasal predilection and wing‑shaped appearance, and the roles of UV radiation in the initiation and the development of pterygia. In the present review, the current understanding of the involvement of UV radiation in the pathogenesis of pterygia is summarized. This involvement includes the alteration of limbal stem cells and fibroblasts that contribute to the initiation of pterygia and the induction of various pro‑inflammatory cytokines, growth factors and matrix metalloproteinases that promote the progression of pterygia. Further elucidation of the roles of UV radiation in the pathogenesis of pterygia may help to encourage individuals at risk of developing pterygia to take preventive measures and aid researchers in the development of novel targeted therapeutic agents to treat pterygia.

Upregulation of Collagen Expression via PPARβ/δ Activation in Aged Skin by Magnesium Lithospermate B from Salvia miltiorrhiza

This study investigated the agonistic activity of magnesium lithospermate B (1), isolated from Salvia miltiorrhiza, on peroxisome proliferator-activated receptor (PPARβ/δ) and the expressions of collagen genes (COL1A1 and COL3A1) and transforming growth factor-β1 (TGF-β1) in models of skin aging. The action of compound 1 as a PPARβ/δ agonist was determined by reporter gene assay, immunostaining, and Western blotting. To determine the antiaging effects of compound 1 on skin, aged Sprague-Dawley rat skin and ultraviolet B (UVB)-irradiated human skin fibroblasts were used. The results show that 1 presented a marked enhancement of both nuclear protein levels and activity of PPARβ/δ in fibroblasts. In addition, 1 prevented downregulation of PPARβ/δ activity in aged rat skin and UVB-induced fibroblasts. Furthermore, 1 increased the expressions of COL1A1, COL3A1, and TGF-β1 in vivo and in a cell culture system. Therefore, the present study shows that compound 1 prevents collagen degradation in aged rat skin and UVB-exposed fibroblasts through PPARβ/δ activation. The therapeutic and cosmetic applications of compound 1 need further investigation.