Is Ras a potential target in treatment against cutaneous squamous cell carcinoma?

The Mutational and Microenvironmental Landscape of Cutaneous Squamous Cell Carcinoma: A Review

Cutaneous squamous cell carcinoma (cSCC) manifests through the complex interactions of UV-induced DNA damage, genetic mutations, and alterations in the tumor microenvironment. A high mutational burden is present in cSCC, as well as both cSCC precursors and normal skin, making driver genes difficult to differentiate. Despite this, several key driver genes have been identified, including TP53, the NOTCH family, CDKN2A, PIK3CA, and EGFR. In addition to mutations, the tumor microenvironment and the manipulation and evasion of the immune system play a critical role in cSCC progression. Novel therapeutic approaches, such as immunotherapy and EGFR inhibitors, have been used to target these dysregulations, and have shown promise in treating advanced cSCC cases, emphasizing the need for targeted interventions considering both genetic and microenvironmental factors for improved patient outcomes.

Exploring Potential Biomarkers, Ferroptosis Mechanisms, and Therapeutic Targets Associated with Cutaneous Squamous Cell Carcinoma via Integrated Transcriptomic Analysis

Background

Cutaneous squamous cell carcinoma (cSCC) is the leading cause of death in patients with nonmelanoma skin cancers (NMSC). However, the unclear pathogenesis of cSCC limits the application of molecular targeted therapy.

Methods

Three microarray datasets (GSE2503, GSE45164, and GSE66359) were downloaded from the Gene Expression Omnibus (GEO). After identifying the differentially expressed genes (DEGs) in tumor and nontumor tissues, five kinds of analyses, namely, functional annotation, protein-protein interaction (PPI) network, hub gene selection, TF-miRNA-mRNA regulatory network analysis, and ferroptosis mechanism, were performed.

Results

A total of 146 DEGs were identified with significant differences, including 113 upregulated genes and 33 downregulated genes. The enriched functions and pathways of the DEGs included microtubule-based movement, ATP binding, cell cycle, P53 signaling pathway, oocyte meiosis, and PLK1 signaling events. Nine hub genes were identified (CDK1, AURKA, RRM2, CENPE, CCNB1, KIAA0101, ZWINT, TOP2A, and ASPM). Finally, RRM2, AURKA, and SAT1 were identified as significant ferroptosis-related genes in cSCC. The differential expression of these genes has been verified in two other independent datasets.

Conclusions

By integrated bioinformatic analysis, the hub genes identified in this study elucidated the molecular mechanism of the pathogenesis and progression of cSCC and are expected to become future biomarkers or therapeutic targets.

Citrus sudachi Peel Extract Suppresses Cell Proliferation and Promotes the Differentiation of Keratinocytes through Inhibition of the EGFR-ERK Signaling Pathway

Citrus sudachi is a well-known fruit in Tokushima Prefecture, Japan, and its peels are rich in phytochemicals, including phenolic compounds. Although it is expected that the extract of the C. sudachi peel elicits various beneficial physiological activities, the effect on the skin has not been investigated. In this study, we report that the aqueous extract from the peel of C. sudachi suppresses cell proliferation of the immortalized human keratinocyte cell line, HaCaT, and primary normal human epidermal keratinocytes. The extract of C. sudachi peel suppressed epidermal growth factor (EGF)-induced EGF receptor activation and tumor necrosis factor (TNF)-α-induced extracellular regulated kinase (ERK) 1/2 activation, which suggests that the extract exerts its inhibitory effect through inhibition of both the EGF receptor (EGFR) and its downstream molecules. Additionally, the extract of C. sudachi peel potentiated calcium-induced keratinocyte differentiation. These results suggest that the extract of C. sudachi peel may have beneficial effects against skin diseases that are characterized by hyperproliferation of epidermal keratinocytes, such as those seen in psoriasis and in cutaneous squamous cell carcinoma.

Apigenin restores impairment of autophagy and downregulation of unfolded protein response regulatory proteins in keratinocytes exposed to ultraviolet B radiation

Ultraviolet (UV)-B radiation is a major environmental risk factor that is responsible for the development and progression of many skin cancers. Apigenin, a type of bioflavonoid, has been reported to inhibit UVB-induced skin cancer. However, how apigenin functions in keratinocytes with UV damage remains unclear. In this study, by lactate dehydrogenase (LDH) release assay, we found that apigenin treatment increased cell death in the primary human epidermal keratinocytes (HEKs) and the cutaneous squamous cell carcinoma cell line COLO-16. Apigenin treatment reduced microtubule-associated protein 1 light chain 3 (LC3)-II turnover, acridine orange staining and GFP-LC3 puncta in both cell types, suggesting autophagy inhibition. However, apigenin treatment restored the inhibition of autophagy in UVB-challenged HEKs. Moreover, apigenin treatment restored the UVB-induced downregulation of ataxia-telangiectasia mutated (ATM), ataxia-telangiectasia, Rad3-related (ATR) and the unfolded protein response (UPR) regulatory proteins, BiP, IRE1α and PERK in HEKs. Apigenin treatment also inhibited UVB-induced apoptosis and cell death in HEKs. In addition, autophagy inhibition by autophagy-related gene (ATG) 5 RNA interference interrupted apigenin-induced restoration of ATR, ATM and BiP, which were downregulated in HEKs exposed to UVB radiation. Our findings indicate that apigenin exhibits a novel protective effect in keratinocytes with UVB damage, suggesting potential application as a photoprotective agent.